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Iwanicki T, Steck M, Bracken-Grissom H, Porter ML. Localization of multiple opsins in ocular and non-ocular tissues of deep-sea shrimps and the first evidence of co-localization in a rhabdomeric R8 cell (Caridea: Oplophoroidea). Vision Res 2024; 219:108403. [PMID: 38581820 DOI: 10.1016/j.visres.2024.108403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/14/2024] [Accepted: 03/25/2024] [Indexed: 04/08/2024]
Abstract
Bioluminescence is a prevalent phenomenon throughout the marine realm and is often the dominant source of light in mesophotic and aphotic depth horizons. Shrimp belonging to the superfamily Oplophoroidea are mesopelagic, perform diel vertical migration, and secrete a bright burst of bioluminescent mucous when threatened. Species in the family Oplophoridae also possess cuticular light-emitting photophores presumably for camouflage via counter-illumination. Many species within the superfamily express a single visual pigment in the retina, consistent with most other large-bodied mesopelagic crustaceans studied to date. Photophore-bearing species have an expanded visual opsin repertoire and dual-sensitivity visual systems, as evidenced by transcriptomes and electroretinograms. In this study, we used immunohistochemistry to describe opsin protein localization in the retinas of four species of Oplophoroidea and non-ocular tissues of Janicella spinicauda. Our results show that Acanthephyra purpurea (Acanthephyridae) retinas possess LWS-only photoreceptors, consistent with the singular peak sensitivity previously reported. Oplophoridae retinas contain two opsin clades (LWS and MWS) consistent with dual-sensitivity. Oplophorus gracilirostris and Systellaspis debilis have LWS in the proximal rhabdom (R1-7 cells) and MWS2 localized in the distal rhabdom (R8 cell). Surprisingly, Janicella spinicauda has LWS in the proximal rhabdom (R1-7) and co-localized MWS1 and MWS2 opsin paralogs in the distal rhabdom, providing the first evidence of co-localization of opsins in a crustacean rhabdomeric R8 cell. Furthermore, opsins were found in multiple non-ocular tissues of J. spinicauda, including nerve, tendon, and photophore. These combined data demonstrate evolutionary novelty and opsin duplication within Oplophoridae, with implications for visual ecology, evolution in mesophotic environments, and a mechanistic understanding of adaptive counter-illumination using photophore bioluminescence.
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Affiliation(s)
- Tom Iwanicki
- The Earth Commons Institute, Georgetown University, Washington, DC 20057, United States; School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, HI 96822, United States; Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology, Washington, DC 20013, United States.
| | - Mireille Steck
- School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, HI 96822, United States
| | - Heather Bracken-Grissom
- Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology, Washington, DC 20013, United States; Institute of Environment, Department of Biology, Florida International University, North Miami, FL 33181, United States
| | - Megan L Porter
- School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, HI 96822, United States
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2
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Gutorov R, Katz B, Peters M, Minke B. Membrane lipid modulations by methyl-β-cyclodextrin uncouple the Drosophila light-activated phospholipase C from TRP and TRPL channel gating. J Biol Chem 2024; 300:105484. [PMID: 37992804 PMCID: PMC10770611 DOI: 10.1016/j.jbc.2023.105484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/05/2023] [Accepted: 11/14/2023] [Indexed: 11/24/2023] Open
Abstract
Sterols are hydrophobic molecules, known to cluster signaling membrane-proteins in lipid rafts, while methyl-β-cyclodextrin (MβCD) has been a major tool for modulating membrane-sterol content for studying its effect on membrane proteins, including the transient receptor potential (TRP) channels. The Drosophila light-sensitive TRP channels are activated downstream of a G-protein-coupled phospholipase Cβ (PLC) cascade. In phototransduction, PLC is an enzyme that hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) generating diacylglycerol, inositol-tris-phosphate, and protons, leading to TRP and TRP-like (TRPL) channel openings. Here, we studied the effects of MβCD on Drosophila phototransduction using electrophysiology while fluorescently monitoring PIP2 hydrolysis, aiming to examine the effects of sterol modulation on PIP2 hydrolysis and the ensuing light-response in the native system. Incubation of photoreceptor cells with MβCD dramatically reduced the amplitude and kinetics of the TRP/TRPL-mediated light response. MβCD also suppressed PLC-dependent TRP/TRPL constitutive channel activity in the dark induced by mitochondrial uncouplers, but PLC-independent activation of the channels by linoleic acid was not affected. Furthermore, MβCD suppressed a constitutively active TRP mutant-channel, trpP365, suggesting that TRP channel activity is a target of MβCD action. Importantly, whole-cell voltage-clamp measurements from photoreceptors and simultaneously monitored PIP2-hydrolysis by translocation of fluorescently tagged Tubby protein domain, from the plasma membrane to the cytosol, revealed that MβCD virtually abolished the light response when having little effect on the light-activated PLC. Together, MβCD uncoupled TRP/TRPL channel gating from light-activated PLC and PIP2-hydrolysis suggesting the involvement of distinct nanoscopic lipid domains such as lipid rafts and PIP2 clusters in TRP/TRPL channel gating.
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Affiliation(s)
- Rita Gutorov
- Faculty of Medicine, Institute for Medical Research Israel-Canada (IMRIC), Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Jerusalem, Israel
| | - Ben Katz
- Faculty of Medicine, Institute for Medical Research Israel-Canada (IMRIC), Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Jerusalem, Israel
| | - Maximilian Peters
- Faculty of Medicine, Institute for Medical Research Israel-Canada (IMRIC), Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Jerusalem, Israel
| | - Baruch Minke
- Faculty of Medicine, Institute for Medical Research Israel-Canada (IMRIC), Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Jerusalem, Israel.
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Xiao N, Xu S, Li ZK, Tang M, Mao R, Yang T, Ma SX, Wang PH, Li MT, Sunilkumar A, Rouyer F, Cao LH, Luo DG. A single photoreceptor splits perception and entrainment by cotransmission. Nature 2023; 623:562-570. [PMID: 37880372 PMCID: PMC10651484 DOI: 10.1038/s41586-023-06681-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 09/26/2023] [Indexed: 10/27/2023]
Abstract
Vision enables both image-forming perception, driven by a contrast-based pathway, and unconscious non-image-forming circadian photoentrainment, driven by an irradiance-based pathway1,2. Although two distinct photoreceptor populations are specialized for each visual task3-6, image-forming photoreceptors can additionally contribute to photoentrainment of the circadian clock in different species7-15. However, it is unknown how the image-forming photoreceptor pathway can functionally implement the segregation of irradiance signals required for circadian photoentrainment from contrast signals required for image perception. Here we report that the Drosophila R8 photoreceptor separates image-forming and irradiance signals by co-transmitting two neurotransmitters, histamine and acetylcholine. This segregation is further established postsynaptically by histamine-receptor-expressing unicolumnar retinotopic neurons and acetylcholine-receptor-expressing multicolumnar integration neurons. The acetylcholine transmission from R8 photoreceptors is sustained by an autocrine negative feedback of the cotransmitted histamine during the light phase of light-dark cycles. At the behavioural level, elimination of histamine and acetylcholine transmission impairs R8-driven motion detection and circadian photoentrainment, respectively. Thus, a single type of photoreceptor can achieve the dichotomy of visual perception and circadian photoentrainment as early as the first visual synapses, revealing a simple yet robust mechanism to segregate and translate distinct sensory features into different animal behaviours.
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Affiliation(s)
- Na Xiao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Shuang Xu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
| | - Ze-Kai Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
| | - Min Tang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Renbo Mao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
| | - Tian Yang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
| | - Si-Xing Ma
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
| | - Peng-Hao Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
| | - Meng-Tong Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- School of Life Sciences, Peking University, Beijing, China
- Zuckerman Mind Brain and Behavior Institute, Columbia University, New York, NY, USA
| | - Ajay Sunilkumar
- Institut des Neurosciences Paris-Saclay, Université Paris-Sud, Université Paris-Saclay, CNRS, Gif-sur-Yvette, France
| | - François Rouyer
- Institut des Neurosciences Paris-Saclay, Université Paris-Sud, Université Paris-Saclay, CNRS, Gif-sur-Yvette, France
| | - Li-Hui Cao
- School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, China
| | - Dong-Gen Luo
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China.
- IDG/McGovern Institute for Brain Research, Peking University, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- School of Life Sciences, Peking University, Beijing, China.
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- Chinese Institute for Brain Research, Beijing, China.
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4
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Sokabe T, Bradshaw HB, Tominaga M, Leishman E, Chandel A, Montell C. Endocannabinoids produced in photoreceptor cells in response to light activate Drosophila TRP channels. Sci Signal 2022; 15:eabl6179. [PMID: 36219683 PMCID: PMC9633101 DOI: 10.1126/scisignal.abl6179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Drosophila phototransduction is a model for signaling cascades that culminate in the activation of transient receptor potential (TRP) cation channels. TRP and TRPL are the canonical TRP (TRPC) channels that are regulated by light stimulation of rhodopsin and engagement of Gαq and phospholipase Cβ (PLC). Lipid metabolite(s) generated downstream of PLC are essential for the activation of the TRPC channels in photoreceptor cells. We sought to identify the key lipids produced subsequent to PLC stimulation that contribute to channel activation. Here, using genetics, lipid analysis, and Ca2+ imaging, we found that light increased the amount of an abundant endocannabinoid, 2-linoleoyl glycerol (2-LG), in vivo. The increase in 2-LG amounts depended on the PLC and diacylglycerol lipase encoded by norpA and inaE, respectively. This endocannabinoid facilitated TRPC-dependent Ca2+ influx in a heterologous expression system and in dissociated ommatidia from compound eyes. Moreover, 2-LG and mechanical stimulation cooperatively activated TRPC channels in ommatidia. We propose that 2-LG is a physiologically relevant endocannabinoid that activates TRPC channels in photoreceptor cells.
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Affiliation(s)
- Takaaki Sokabe
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara; California 93106, USA
- Division of Cell Signaling, National Institute for Physiological Sciences, and Thermal Biology Group, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences; Okazaki, Aichi, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI; Okazaki, Aichi, 444-8787, Japan
| | - Heather B. Bradshaw
- Department of Psychological and Brain Sciences, Indiana University; Bloomington, Indiana, 47405, USA
| | - Makoto Tominaga
- Division of Cell Signaling, National Institute for Physiological Sciences, and Thermal Biology Group, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences; Okazaki, Aichi, 444-8787, Japan
- Department of Physiological Sciences, SOKENDAI; Okazaki, Aichi, 444-8787, Japan
| | - Emma Leishman
- Department of Psychological and Brain Sciences, Indiana University; Bloomington, Indiana, 47405, USA
| | - Avinash Chandel
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara; California 93106, USA
| | - Craig Montell
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara; California 93106, USA
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5
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Voortman L, Anderson C, Urban E, Yuan L, Tran S, Neuhaus-Follini A, Derrick J, Gregor T, Johnston RJ. Temporally dynamic antagonism between transcription and chromatin compaction controls stochastic photoreceptor specification in flies. Dev Cell 2022; 57:1817-1832.e5. [PMID: 35835116 PMCID: PMC9378680 DOI: 10.1016/j.devcel.2022.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 05/09/2022] [Accepted: 06/20/2022] [Indexed: 01/12/2023]
Abstract
Stochastic mechanisms diversify cell fates during development. How cells randomly choose between two or more fates remains poorly understood. In the Drosophila eye, the random mosaic of two R7 photoreceptor subtypes is determined by expression of the transcription factor Spineless (Ss). We investigated how cis-regulatory elements and trans factors regulate nascent transcriptional activity and chromatin compaction at the ss gene locus during R7 development. The ss locus is in a compact state in undifferentiated cells. An early enhancer drives transcription in all R7 precursors, and the locus opens. In differentiating cells, transcription ceases and the ss locus stochastically remains open or compacts. In SsON R7s, ss is open and competent for activation by a late enhancer, whereas in SsOFF R7s, ss is compact, and repression prevents expression. Our results suggest that a temporally dynamic antagonism, in which transcription drives large-scale decompaction and then compaction represses transcription, controls stochastic fate specification.
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Affiliation(s)
- Lukas Voortman
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Elizabeth Urban
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Luorongxin Yuan
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sang Tran
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Josh Derrick
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Thomas Gregor
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA; Joseph Henry Laboratories of Physics, the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Developmental and Stem Cell Biology, UMR3738, Institut Pasteur, 75015 Paris, France
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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6
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Jauregui-Lozano J, Hall H, Stanhope SC, Bakhle K, Marlin MM, Weake VM. The Clock:Cycle complex is a major transcriptional regulator of Drosophila photoreceptors that protects the eye from retinal degeneration and oxidative stress. PLoS Genet 2022; 18:e1010021. [PMID: 35100266 PMCID: PMC8830735 DOI: 10.1371/journal.pgen.1010021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/10/2022] [Accepted: 01/08/2022] [Indexed: 12/28/2022] Open
Abstract
The aging eye experiences physiological changes that include decreased visual function and increased risk of retinal degeneration. Although there are transcriptomic signatures in the aging retina that correlate with these physiological changes, the gene regulatory mechanisms that contribute to cellular homeostasis during aging remain to be determined. Here, we integrated ATAC-seq and RNA-seq data to identify 57 transcription factors that showed differential activity in aging Drosophila photoreceptors. These 57 age-regulated transcription factors include two circadian regulators, Clock and Cycle, that showed sustained increased activity during aging. When we disrupted the Clock:Cycle complex by expressing a dominant negative version of Clock (ClkDN) in adult photoreceptors, we observed changes in expression of 15–20% of genes including key components of the phototransduction machinery and many eye-specific transcription factors. Using ATAC-seq, we showed that expression of ClkDN in photoreceptors leads to changes in activity of 37 transcription factors and causes a progressive decrease in global levels of chromatin accessibility in photoreceptors. Supporting a key role for Clock-dependent transcription in the eye, expression of ClkDN in photoreceptors also induced light-dependent retinal degeneration and increased oxidative stress, independent of light exposure. Together, our data suggests that the circadian regulators Clock and Cycle act as neuroprotective factors in the aging eye by directing gene regulatory networks that maintain expression of the phototransduction machinery and counteract oxidative stress. Age-associated changes to the retinal transcriptome often correlate with physiological changes, such as loss of visual function and increase in cell death. However, the mechanisms that contribute to these transcriptomic changes are poorly understood. Here, we used a genomics/bioinformatics approach to identify transcription factor binding sites with differential activity in aging Drosophila retina outer photoreceptors. Amongst these age-regulated transcription factors, we identify the circadian regulators Clock and Cycle. Using a genetics approach, we find that photoreceptor-specific disruption of the Clock:Cycle complex makes the Drosophila eye susceptible to light-dependent retinal degeneration, and light-independent increase of oxidative stress, showing that a functional circadian clock contributes to visual health and function in Drosophila. Because disruption of circadian rhythms has been associated with the onset of several age-related eye diseases, our data shows that the Drosophila retina serves as a useful model to study how disruption of the circadian clock contributes to neurodegeneration in the retina.
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Affiliation(s)
- Juan Jauregui-Lozano
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
| | - Hana Hall
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
| | - Sarah C. Stanhope
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
| | - Kimaya Bakhle
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
| | - Makayla M. Marlin
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
| | - Vikki M. Weake
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Center for Cancer Research, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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7
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Escobedo SE, Shah A, Easton AN, Hall H, Weake VM. Characterizing a gene expression toolkit for eye- and photoreceptor-specific expression in Drosophila. Fly (Austin) 2021; 15:73-88. [PMID: 33899690 PMCID: PMC8078738 DOI: 10.1080/19336934.2021.1915683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/16/2021] [Accepted: 04/08/2021] [Indexed: 10/21/2022] Open
Abstract
Binary expression systems are a powerful tool for tissue- and cell-specific research. Many of the currently available Drosophila eye-specific drivers have not been systematically characterized for their expression level and cell-type specificity in the adult eye or during development. Here, we used a luciferase reporter to measure expression levels of different drivers in the adult Drosophila eye, and characterized the cell type-specificity of each driver using a fluorescent reporter in live 10-day-old adult males. We also further characterized the expression pattern of these drivers in various developmental stages. We compared several Gal4 drivers from the Bloomington Drosophila Stock Center (BDSC) including GMR-Gal4, longGMR-Gal4 and Rh1-Gal4 with newly developed Gal4 and QF2 drivers that are specific to different cell types in the adult eye. In addition, we generated drug-inducible Rh1-GSGal4 lines and compared their induced expression with an available GMR-GSGal4 line. Although both lines had significant induction of gene expression measured by luciferase activity, Rh1-GSGal4 was expressed at levels below the detection of the fluorescent reporter by confocal microscopy, while GMR-GSGal4 showed substantial reporter expression in the absence of drug by microscopy. Overall, our study systematically characterizes and compares a large toolkit of eye- and photoreceptor-specific drivers, while also uncovering some of the limitations of currently available expression systems in the adult eye.
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Affiliation(s)
| | - Aashka Shah
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
| | - Alyssa N. Easton
- Department of Agriculture and Biological Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Hana Hall
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
| | - Vikki M. Weake
- Department of Biochemistry, Purdue University, West Lafayette, Indiana, USA
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana, USA
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8
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Charlton-Perkins MA, Friedrich M, Cook TA. Semper's cells in the insect compound eye: Insights into ocular form and function. Dev Biol 2021; 479:126-138. [PMID: 34343526 PMCID: PMC8410683 DOI: 10.1016/j.ydbio.2021.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 11/28/2022]
Abstract
The arthropod compound eye represents one of two major eye types in the animal kingdom and has served as an essential experimental paradigm for defining fundamental mechanisms underlying sensory organ formation, function, and maintenance. One of the most distinguishing features of the compound eye is the highly regular array of lens facets that define individual eye (ommatidial) units. These lens facets are produced by a deeply conserved quartet of cuticle-secreting cells, called Semper cells (SCs). Also widely known as cone cells, SCs were originally identified for their secretion of the dioptric system, i.e. the corneal lens and underlying crystalline cones. Additionally, SCs are now known to execute a diversity of patterning and glial functions in compound eye development and maintenance. Here, we present an integrated account of our current knowledge of SC multifunctionality in the Drosophila compound eye, highlighting emerging gene regulatory modules that may drive the diverse roles for these cells. Drawing comparisons with other deeply conserved retinal glia in the vertebrate single lens eye, this discussion speaks to glial cell origins and opens new avenues for understanding sensory system support programs.
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Affiliation(s)
- Mark A Charlton-Perkins
- Department of Paediatrics, Wellcome-MRC Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, United Kingdom
| | - Markus Friedrich
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI, 48202, USA; Department of Ophthalmological, Visual, and Anatomical Sciences, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA
| | - Tiffany A Cook
- Department of Ophthalmological, Visual, and Anatomical Sciences, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA; Center of Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA.
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9
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Huang HW, Ryoo HD. Drosophila fabp is required for light-dependent Rhodopsin-1 clearance and photoreceptor survival. PLoS Genet 2021; 17:e1009551. [PMID: 34714826 PMCID: PMC8580249 DOI: 10.1371/journal.pgen.1009551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 11/10/2021] [Accepted: 10/20/2021] [Indexed: 12/30/2022] Open
Abstract
Rhodopsins are light-detecting proteins coupled with retinal chromophores essential for visual function. Coincidentally, dysfunctional Rhodopsin homeostasis underlies retinal degeneration in humans and model organisms. Drosophila ninaEG69D mutant is one such example, where the encoded Rh1 protein imposes endoplasmic reticulum (ER) stress and causes light-dependent retinal degeneration. The underlying reason for such light-dependency remains unknown. Here, we report that Drosophila fatty acid binding protein (fabp) is a gene induced in ninaEG69D/+ photoreceptors, and regulates light-dependent Rhodopsin-1 (Rh1) protein clearance and photoreceptor survival. Specifically, our photoreceptor-specific gene expression profiling study in ninaEG69D/+ flies revealed increased expression of fabp together with other genes that control light-dependent Rh1 protein degradation. fabp induction in ninaEG69D photoreceptors required vitamin A and its transporter genes. In flies reared under light, loss of fabp caused an accumulation of Rh1 proteins in cytoplasmic vesicles. The increase in Rh1 levels under these conditions was dependent on Arrestin2 that mediates feedback inhibition of light-activated Rh1. fabp mutants exhibited light-dependent retinal degeneration, a phenotype also found in other mutants that block light-induced Rh1 degradation. These observations reveal a previously unrecognized link between light-dependent Rh1 proteostasis and the ER-stress imposing ninaEG69D mutant that cause retinal degeneration.
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Affiliation(s)
- Huai-Wei Huang
- Department of Cell Biology NYU Grossman School of Medicine New York, New York, United States of America
| | - Hyung Don Ryoo
- Department of Cell Biology NYU Grossman School of Medicine New York, New York, United States of America
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10
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Smylla TK, Wagner K, Huber A. Application of Fluorescent Proteins for Functional Dissection of the Drosophila Visual System. Int J Mol Sci 2021; 22:8930. [PMID: 34445636 PMCID: PMC8396179 DOI: 10.3390/ijms22168930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 11/22/2022] Open
Abstract
The Drosophila eye has been used extensively to study numerous aspects of biological systems, for example, spatio-temporal regulation of differentiation, visual signal transduction, protein trafficking and neurodegeneration. Right from the advent of fluorescent proteins (FPs) near the end of the millennium, heterologously expressed fusion proteins comprising FPs have been applied in Drosophila vision research not only for subcellular localization of proteins but also for genetic screens and analysis of photoreceptor function. Here, we summarize applications for FPs used in the Drosophila eye as part of genetic screens, to study rhodopsin expression patterns, subcellular protein localization, membrane protein transport or as genetically encoded biosensors for Ca2+ and phospholipids in vivo. We also discuss recently developed FPs that are suitable for super-resolution or correlative light and electron microscopy (CLEM) approaches. Illustrating the possibilities provided by using FPs in Drosophila photoreceptors may aid research in other sensory or neuronal systems that have not yet been studied as well as the Drosophila eye.
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Affiliation(s)
- Thomas K. Smylla
- Department of Biochemistry, Institute of Biology, University of Hohenheim, 70599 Stuttgart, Germany; (K.W.); (A.H.)
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11
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Poupault C, Choi D, Lam-Kamath K, Dewett D, Razzaq A, Bunker J, Perry A, Cho I, Rister J. A combinatorial cis-regulatory logic restricts color-sensing Rhodopsins to specific photoreceptor subsets in Drosophila. PLoS Genet 2021; 17:e1009613. [PMID: 34161320 PMCID: PMC8259978 DOI: 10.1371/journal.pgen.1009613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 07/06/2021] [Accepted: 05/19/2021] [Indexed: 11/18/2022] Open
Abstract
Color vision in Drosophila melanogaster is based on the expression of five different color-sensing Rhodopsin proteins in distinct subtypes of photoreceptor neurons. Promoter regions of less than 300 base pairs are sufficient to reproduce the unique, photoreceptor subtype-specific rhodopsin expression patterns. The underlying cis-regulatory logic remains poorly understood, but it has been proposed that the rhodopsin promoters have a bipartite structure: the distal promoter region directs the highly restricted expression in a specific photoreceptor subtype, while the proximal core promoter region provides general activation in all photoreceptors. Here, we investigate whether the rhodopsin promoters exhibit a strict specialization of their distal (subtype specificity) and proximal (general activation) promoter regions, or if both promoter regions contribute to generating the photoreceptor subtype-specific expression pattern. To distinguish between these two models, we analyze the expression patterns of a set of hybrid promoters that combine the distal promoter region of one rhodopsin with the proximal core promoter region of another rhodopsin. We find that the function of the proximal core promoter regions extends beyond providing general activation: these regions play a previously underappreciated role in generating the non-overlapping expression patterns of the different rhodopsins. Therefore, cis-regulatory motifs in both the distal and the proximal core promoter regions recruit transcription factors that generate the unique rhodopsin patterns in a combinatorial manner. We compare this combinatorial regulatory logic to the regulatory logic of olfactory receptor genes and discuss potential implications for the evolution of rhodopsins. Each type of sensory receptor neuron in our body expresses a specific sensory receptor protein, which allows us to detect and discriminate a variety of environmental stimuli. The regulatory logic that controls this spatially precise and highly restricted expression of sensory receptor proteins remains poorly understood. As a model system, we study the mechanisms that control the expression of different color-sensing Rhodopsin proteins in distinct subtypes of Drosophila photoreceptors, which is the basis for color vision. Compact promoter regions of less than 300 base pairs are sufficient to reproduce the non-overlapping rhodopsin patterns. However, the regulatory logic that underlies the combination (sometimes called ‘grammar’) of the cis-regulatory motifs (sometimes called ‘vocabulary’) within the rhodopsin promoters remains poorly understood. Here, we find that specific combinations of cis-regulatory motifs in the distal and the proximal core promoter regions of each rhodopsin direct its unique expression pattern.
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Affiliation(s)
- Clara Poupault
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Diane Choi
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Khanh Lam-Kamath
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Deepshe Dewett
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Ansa Razzaq
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Joseph Bunker
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Alexis Perry
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Irene Cho
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Jens Rister
- Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America
- * E-mail:
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12
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Tzou FY, Su TY, Lin WS, Kuo HC, Yu YL, Yeh YH, Liu CC, Kuo CH, Huang SY, Chan CC. Dihydroceramide desaturase regulates the compartmentalization of Rac1 for neuronal oxidative stress. Cell Rep 2021; 35:108972. [PMID: 33852856 DOI: 10.1016/j.celrep.2021.108972] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 01/18/2021] [Accepted: 03/19/2021] [Indexed: 11/19/2022] Open
Abstract
Disruption of sphingolipid homeostasis is known to cause neurological disorders, but the mechanisms by which specific sphingolipid species modulate pathogenesis remain unclear. The last step of de novo sphingolipid synthesis is the conversion of dihydroceramide to ceramide by dihydroceramide desaturase (human DEGS1; Drosophila Ifc). Loss of ifc leads to dihydroceramide accumulation, oxidative stress, and photoreceptor degeneration, whereas human DEGS1 variants are associated with leukodystrophy and neuropathy. In this work, we demonstrate that DEGS1/ifc regulates Rac1 compartmentalization in neuronal cells and that dihydroceramide alters the association of active Rac1 with organelle-mimicking membranes. We further identify the Rac1-NADPH oxidase (NOX) complex as the major cause of reactive oxygen species (ROS) accumulation in ifc-knockout (ifc-KO) photoreceptors and in SH-SY5Y cells with the leukodystrophy-associated DEGS1H132R variant. Suppression of Rac1-NOX activity rescues degeneration of ifc-KO photoreceptors and ameliorates oxidative stress in DEGS1H132R-carrying cells. Therefore, we conclude that DEGS1/ifc deficiency causes dihydroceramide accumulation, resulting in Rac1 mislocalization and NOX-dependent neurodegeneration.
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Affiliation(s)
- Fei-Yang Tzou
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Tsu-Yi Su
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Wan-Syuan Lin
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Han-Chun Kuo
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yu-Lian Yu
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yu-Han Yeh
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chung-Chih Liu
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Ching-Hua Kuo
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
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13
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Liénard MA, Bernard GD, Allen A, Lassance JM, Song S, Childers RR, Yu N, Ye D, Stephenson A, Valencia-Montoya WA, Salzman S, Whitaker MRL, Calonje M, Zhang F, Pierce NE. The evolution of red color vision is linked to coordinated rhodopsin tuning in lycaenid butterflies. Proc Natl Acad Sci U S A 2021; 118:e2008986118. [PMID: 33547236 PMCID: PMC8017955 DOI: 10.1073/pnas.2008986118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Color vision has evolved multiple times in both vertebrates and invertebrates and is largely determined by the number and variation in spectral sensitivities of distinct opsin subclasses. However, because of the difficulty of expressing long-wavelength (LW) invertebrate opsins in vitro, our understanding of the molecular basis of functional shifts in opsin spectral sensitivities has been biased toward research primarily in vertebrates. This has restricted our ability to address whether invertebrate Gq protein-coupled opsins function in a novel or convergent way compared to vertebrate Gt opsins. Here we develop a robust heterologous expression system to purify invertebrate rhodopsins, identify specific amino acid changes responsible for adaptive spectral tuning, and pinpoint how molecular variation in invertebrate opsins underlie wavelength sensitivity shifts that enhance visual perception. By combining functional and optophysiological approaches, we disentangle the relative contributions of lateral filtering pigments from red-shifted LW and blue short-wavelength opsins expressed in distinct photoreceptor cells of individual ommatidia. We use in situ hybridization to visualize six ommatidial classes in the compound eye of a lycaenid butterfly with a four-opsin visual system. We show experimentally that certain key tuning residues underlying green spectral shifts in blue opsin paralogs have evolved repeatedly among short-wavelength opsin lineages. Taken together, our results demonstrate the interplay between regulatory and adaptive evolution at multiple Gq opsin loci, as well as how coordinated spectral shifts in LW and blue opsins can act together to enhance insect spectral sensitivity at blue and red wavelengths for visual performance adaptation.
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Affiliation(s)
- Marjorie A Liénard
- Broad Institute of MIT and Harvard University, Cambridge, MA 02142;
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Gary D Bernard
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195
| | - Andrew Allen
- Broad Institute of MIT and Harvard University, Cambridge, MA 02142
| | - Jean-Marc Lassance
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Siliang Song
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Richard Rabideau Childers
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Nanfang Yu
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027
| | - Dajia Ye
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Adriana Stephenson
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Wendy A Valencia-Montoya
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Shayla Salzman
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Melissa R L Whitaker
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | | | - Feng Zhang
- Broad Institute of MIT and Harvard University, Cambridge, MA 02142
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Cambridge, MA 02139
| | - Naomi E Pierce
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138;
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14
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Tan H, Fulton RE, Chou WH, Birkholz DA, Mannino MP, Yamaguchi DM, Aldrich JC, Jacobsen TL, Britt SG. Drosophila R8 photoreceptor cell subtype specification requires hibris. PLoS One 2020; 15:e0240451. [PMID: 33052948 PMCID: PMC7556441 DOI: 10.1371/journal.pone.0240451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 09/25/2020] [Indexed: 11/18/2022] Open
Abstract
Cell differentiation and cell fate determination in sensory systems are essential for stimulus discrimination and coding of environmental stimuli. Color vision is based on the differential color sensitivity of retinal photoreceptors, however the developmental programs that control photoreceptor cell differentiation and specify color sensitivity are poorly understood. In Drosophila melanogaster, there is evidence that the color sensitivity of different photoreceptors in the compound eye is regulated by inductive signals between cells, but the exact nature of these signals and how they are propagated remains unknown. We conducted a genetic screen to identify additional regulators of this process and identified a novel mutation in the hibris gene, which encodes an irre cell recognition module protein (IRM). These immunoglobulin super family cell adhesion molecules include human KIRREL and nephrin (NPHS1). hibris is expressed dynamically in the developing Drosophila melanogaster eye and loss-of-function mutations give rise to a diverse range of mutant phenotypes including disruption of the specification of R8 photoreceptor cell diversity. We demonstrate that hibris is required within the retina, and that hibris over-expression is sufficient to disrupt normal photoreceptor cell patterning. These findings suggest an additional layer of complexity in the signaling process that produces paired expression of opsin genes in adjacent R7 and R8 photoreceptor cells.
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Affiliation(s)
- Hong Tan
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Ruth E. Fulton
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Wen-Hai Chou
- Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Denise A. Birkholz
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Meridee P. Mannino
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - David M. Yamaguchi
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - John C. Aldrich
- Department of Neurology, Department of Ophthalmology, Dell Medical School, University of Texas at Austin, Austin, Texas, United States of America
| | - Thomas L. Jacobsen
- Department of Neurology, Department of Ophthalmology, Dell Medical School, University of Texas at Austin, Austin, Texas, United States of America
| | - Steven G. Britt
- Department of Neurology, Department of Ophthalmology, Dell Medical School, University of Texas at Austin, Austin, Texas, United States of America
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15
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Zelhof AC, Mahato S, Liang X, Rylee J, Bergh E, Feder LE, Larsen ME, Britt SG, Friedrich M. The brachyceran de novo gene PIP82, a phosphorylation target of aPKC, is essential for proper formation and maintenance of the rhabdomeric photoreceptor apical domain in Drosophila. PLoS Genet 2020; 16:e1008890. [PMID: 32579558 PMCID: PMC7340324 DOI: 10.1371/journal.pgen.1008890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 07/07/2020] [Accepted: 05/27/2020] [Indexed: 11/18/2022] Open
Abstract
The Drosophila apical photoreceptor membrane is defined by the presence of two distinct morphological regions, the microvilli-based rhabdomere and the stalk membrane. The subdivision of the apical membrane contributes to the geometrical positioning and the stereotypical morphology of the rhabdomeres in compound eyes with open rhabdoms and neural superposition. Here we describe the characterization of the photoreceptor specific protein PIP82. We found that PIP82's subcellular localization demarcates the rhabdomeric portion of the apical membrane. We further demonstrate that PIP82 is a phosphorylation target of aPKC. PIP82 localization is modulated by phosphorylation, and in vivo, the loss of the aPKC/Crumbs complex results in an expansion of the PIP82 localization domain. The absence of PIP82 in photoreceptors leads to misshapped rhabdomeres as a result of misdirected cellular trafficking of rhabdomere proteins. Comparative analyses reveal that PIP82 originated de novo in the lineage leading to brachyceran Diptera, which is also characterized by the transition from fused to open rhabdoms. Taken together, these findings define a novel factor that delineates and maintains a specific apical membrane domain, and offers new insights into the functional organization and evolutionary history of the Drosophila retina.
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Affiliation(s)
- Andrew C. Zelhof
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Simpla Mahato
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Xulong Liang
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Jonathan Rylee
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Emma Bergh
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Lauren E. Feder
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Matthew E. Larsen
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas, Austin, Texas, United States of America
| | - Steven G. Britt
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas, Austin, Texas, United States of America
| | - Markus Friedrich
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
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16
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Terzioğlu Kara E, Kiral FR, Öztürk Çolak A, Çelik A. Generation and characterization of inner photoreceptor-specific enhancer-trap lines using a novel piggyBac-Gal4 element in Drosophila. Arch Insect Biochem Physiol 2020; 104:e21675. [PMID: 32285519 DOI: 10.1002/arch.21675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/17/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
The Drosophila inner photoreceptors R7 and R8 are responsible for color vision and their differentiation starts at the third instar larval stage. Only a handful of genes with R7 or R8-cell-specific expression are known. We performed an enhancer-trap screen using a novel piggyBac transposable element, pBGay, carrying a Gal4 sequence under the control of the P promoter to identify novel genes expressed specifically in R7 or R8 cells. From this screen, three lines were analyzed in detail: piggyBacAC109 and piggyBacAC783 are expressed in R8 cells and piggyBacAC887 is expressed in R7 cells at the third instar larval stage and pupal stages. Molecular analysis showed that the piggyBac elements were inserted into the first intron of CG14160 and CG7985 genes and the second intron of unzipped. We show the expression pattern in the developing eye imaginal disc, pupal retina as well as the adult retina. The photoreceptor-specific expression of these genes is reported for the first time and we propose that these lines are useful tools for studying the development of the visual system.
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Affiliation(s)
- Ece Terzioğlu Kara
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Bogazici University, Istanbul, Turkey
| | - Ferdi Rıdvan Kiral
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Bogazici University, Istanbul, Turkey
- Division of Neurobiology, Institute for Biology, Free University Berlin, Berlin, Germany
| | - Arzu Öztürk Çolak
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Bogazici University, Istanbul, Turkey
| | - Arzu Çelik
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Bogazici University, Istanbul, Turkey
- Center for Life Sciences and Technologies, Bogazici University, Istanbul, Turkey
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17
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Kraut RS, Knust E. Changes in endolysosomal organization define a pre-degenerative state in the crumbs mutant Drosophila retina. PLoS One 2019; 14:e0220220. [PMID: 31834921 PMCID: PMC6910688 DOI: 10.1371/journal.pone.0220220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/24/2019] [Indexed: 01/06/2023] Open
Abstract
Mutations in the epithelial polarity gene crumbs (crb) lead to retinal degeneration in Drosophila and in humans. The overall morphology of the retina and its deterioration in Drosophila crb mutants has been well-characterized, but the cell biological origin of the degeneration is not well understood. Degenerative conditions in the retina and elsewhere in the nervous system often involve defects in degradative intracellular trafficking pathways. So far, however, effects of crb on the endolysosomal system, or on the spatial organization of these compartments in photoreceptor cells have not been described. We therefore asked whether photoreceptors in crb mutants exhibit alterations in endolysosomal compartments under pre-degenerative conditions, where the retina is still morphologically intact. Data presented here show that, already well before the onset of degeneration, Arl8, Rab7, and Atg8-carrying endolysosomal and autophagosomal compartments undergo changes in morphology and positioning with respect to each other in crb mutant retinas. We propose that these changes may be early signs of the degeneration-prone condition in crb retinas.
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Affiliation(s)
- Rachel S. Kraut
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse, Dresden, Germany
- * E-mail:
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse, Dresden, Germany
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18
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Gür B, Sporar K, Lopez-Behling A, Silies M. Distinct expression of potassium channels regulates visual response properties of lamina neurons in Drosophila melanogaster. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:273-287. [PMID: 31823004 DOI: 10.1007/s00359-019-01385-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/23/2019] [Accepted: 11/21/2019] [Indexed: 01/11/2023]
Abstract
The computational organization of sensory systems depends on the diversification of individual cell types with distinct signal-processing capabilities. The Drosophila visual system, for instance, splits information into channels with different temporal properties directly downstream of photoreceptors in the first-order interneurons of the OFF pathway, L2 and L3. However, the biophysical mechanisms that determine this specialization are largely unknown. Here, we show that the voltage-gated Ka channels Shaker and Shal contribute to the response properties of the major OFF pathway input L2. L3 calcium response kinetics postsynaptic to photoreceptors resemble the sustained calcium signals of photoreceptors, whereas L2 neurons decay transiently. Based on a cell-type-specific RNA-seq data set and endogenous protein tagging, we identified Shaker and Shal as the primary candidates to shape L2 responses. Using in vivo two-photon imaging of L2 calcium signals in combination with pharmacological and genetic perturbations of these Ka channels, we show that the wild-type Shaker and Shal function is to enhance L2 responses and cell-autonomously sharpen L2 kinetics. Our results reveal a role for Ka channels in determining the signal-processing characteristics of a specific cell type in the visual system.
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Affiliation(s)
- Burak Gür
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- European Neuroscience Institute Göttingen a Joint Initiative of the University Medical Center Göttingen, and the Max Planck Society, 37077, Göttingen, Germany
- International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of Göttingen, Göttingen, Germany
| | - Katja Sporar
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- European Neuroscience Institute Göttingen a Joint Initiative of the University Medical Center Göttingen, and the Max Planck Society, 37077, Göttingen, Germany
- International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of Göttingen, Göttingen, Germany
| | - Anne Lopez-Behling
- European Neuroscience Institute Göttingen a Joint Initiative of the University Medical Center Göttingen, and the Max Planck Society, 37077, Göttingen, Germany
| | - Marion Silies
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany.
- European Neuroscience Institute Göttingen a Joint Initiative of the University Medical Center Göttingen, and the Max Planck Society, 37077, Göttingen, Germany.
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19
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Menon KP, Kulkarni V, Takemura SY, Anaya M, Zinn K. Interactions between Dpr11 and DIP-γ control selection of amacrine neurons in Drosophila color vision circuits. eLife 2019; 8:e48935. [PMID: 31692445 PMCID: PMC6879306 DOI: 10.7554/elife.48935] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/05/2019] [Indexed: 12/17/2022] Open
Abstract
Drosophila R7 UV photoreceptors (PRs) are divided into yellow (y) and pale (p) subtypes. yR7 PRs express the Dpr11 cell surface protein and are presynaptic to Dm8 amacrine neurons (yDm8) that express Dpr11's binding partner DIP-γ, while pR7 PRs synapse onto DIP-γ-negative pDm8. Dpr11 and DIP-γ expression patterns define 'yellow' and 'pale' color vision circuits. We examined Dm8 neurons in these circuits by electron microscopic reconstruction and expansion microscopy. DIP-γ and dpr11 mutations affect the morphologies of yDm8 distal ('home column') dendrites. yDm8 neurons are generated in excess during development and compete for presynaptic yR7 PRs, and interactions between Dpr11 and DIP-γ are required for yDm8 survival. These interactions also allow yDm8 neurons to select yR7 PRs as their appropriate home column partners. yDm8 and pDm8 neurons do not normally compete for survival signals or R7 partners, but can be forced to do so by manipulation of R7 subtype fate.
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Affiliation(s)
- Kaushiki P Menon
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Vivek Kulkarni
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Shin-ya Takemura
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Michael Anaya
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Kai Zinn
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
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20
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Helfrich-Förster C. Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:259-272. [PMID: 31691095 PMCID: PMC7069913 DOI: 10.1007/s00359-019-01379-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/19/2019] [Accepted: 10/26/2019] [Indexed: 12/26/2022]
Abstract
Light is the most important Zeitgeber for entraining animal activity rhythms to the 24-h day. In all animals, the eyes are the main visual organs that are not only responsible for motion and colour (image) vision, but also transfer light information to the circadian clock in the brain. The way in which light entrains the circadian clock appears, however, variable in different species. As do vertebrates, insects possess extraretinal photoreceptors in addition to their eyes (and ocelli) that are sometimes located close to (underneath) the eyes, but sometimes even in the central brain. These extraretinal photoreceptors contribute to entrainment of their circadian clocks to different degrees. The fruit fly Drosophila melanogaster is special, because it expresses the blue light-sensitive cryptochrome (CRY) directly in its circadian clock neurons, and CRY is usually regarded as the fly’s main circadian photoreceptor. Nevertheless, recent studies show that the retinal and extraretinal eyes transfer light information to almost every clock neuron and that the eyes are similarly important for entraining the fly’s activity rhythm as in other insects, or more generally spoken in other animals. Here, I compare the light input pathways between selected insect species with a focus on Drosophila’s special case.
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21
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Li X, Abou Tayoun A, Song Z, Dau A, Rien D, Jaciuch D, Dongre S, Blanchard F, Nikolaev A, Zheng L, Bollepalli MK, Chu B, Hardie RC, Dolph PJ, Juusola M. Ca 2+-Activated K + Channels Reduce Network Excitability, Improving Adaptability and Energetics for Transmitting and Perceiving Sensory Information. J Neurosci 2019; 39:7132-7154. [PMID: 31350259 PMCID: PMC6733542 DOI: 10.1523/jneurosci.3213-18.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 11/21/2022] Open
Abstract
Ca2+-activated K+ channels (BK and SK) are ubiquitous in synaptic circuits, but their role in network adaptation and sensory perception remains largely unknown. Using electrophysiological and behavioral assays and biophysical modeling, we discover how visual information transfer in mutants lacking the BK channel (dSlo- ), SK channel (dSK- ), or both (dSK- ;; dSlo- ) is shaped in the female fruit fly (Drosophila melanogaster) R1-R6 photoreceptor-LMC circuits (R-LMC-R system) through synaptic feedforward-feedback interactions and reduced R1-R6 Shaker and Shab K+ conductances. This homeostatic compensation is specific for each mutant, leading to distinctive adaptive dynamics. We show how these dynamics inescapably increase the energy cost of information and promote the mutants' distorted motion perception, determining the true price and limits of chronic homeostatic compensation in an in vivo genetic animal model. These results reveal why Ca2+-activated K+ channels reduce network excitability (energetics), improving neural adaptability for transmitting and perceiving sensory information.SIGNIFICANCE STATEMENT In this study, we directly link in vivo and ex vivo experiments with detailed stochastically operating biophysical models to extract new mechanistic knowledge of how Drosophila photoreceptor-interneuron-photoreceptor (R-LMC-R) circuitry homeostatically retains its information sampling and transmission capacity against chronic perturbations in its ion-channel composition, and what is the cost of this compensation and its impact on optomotor behavior. We anticipate that this novel approach will provide a useful template to other model organisms and computational neuroscience, in general, in dissecting fundamental mechanisms of homeostatic compensation and deepening our understanding of how biological neural networks work.
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Affiliation(s)
- Xiaofeng Li
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Ahmad Abou Tayoun
- Department of Biology, Dartmouth College, Hanover, New Hampshire 03755
| | - Zhuoyi Song
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, and Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai 200433, China, and
| | - An Dau
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Diana Rien
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - David Jaciuch
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Sidhartha Dongre
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Florence Blanchard
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Anton Nikolaev
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Lei Zheng
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Murali K Bollepalli
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, and Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai 200433, China, and
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Brian Chu
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, and Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai 200433, China, and
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Roger C Hardie
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, and Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai 200433, China, and
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Patrick J Dolph
- Department of Biology, Dartmouth College, Hanover, New Hampshire 03755,
| | - Mikko Juusola
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China,
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
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22
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Neal S, de Jong DM, Seaver EC. CRISPR/CAS9 mutagenesis of a single r-opsin gene blocks phototaxis in a marine larva. Proc Biol Sci 2019; 286:20182491. [PMID: 31161907 PMCID: PMC6571462 DOI: 10.1098/rspb.2018.2491] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 05/09/2019] [Indexed: 11/17/2022] Open
Abstract
Many marine animals depend upon a larval phase of their life cycle to locate suitable habitat, and larvae use light detection to influence swimming behaviour and dispersal. Light detection is mediated by the opsin genes, which encode light-sensitive transmembrane proteins. Previous studies suggest that r-opsins in the eyes mediate locomotory behaviour in marine protostomes, but few have provided direct evidence through gene mutagenesis. Larvae of the marine annelid Capitella teleta have simple eyespots and are positively phototactic, although the molecular components that mediate this behaviour are unknown. Here, we characterize the spatio-temporal expression of the rhabdomeric opsin genes in C. teleta and show that a single rhabdomeric opsin gene, Ct-r-opsin1, is expressed in the larval photoreceptor cells. To investigate its function, Ct-r-opsin1 was disrupted using CRISPR/CAS9 mutagenesis. Polymerase chain reaction amplification and DNA sequencing demonstrated efficient editing of the Ct-r-opsin1 locus. In addition, the pattern of Ct-r-opsin1 expression in photoreceptor cells was altered. Notably, there was a significant decrease in larval phototaxis, although the eyespot photoreceptor cell and associated pigment cell formed normally and persisted in Ct-r-opsin1-mutant animals. The loss of phototaxis owing to mutations in Ct-r-opsin1 is similar to that observed when the entire photoreceptor and pigment cell are deleted, demonstrating that a single r-opsin gene is sufficient to mediate phototaxis in C. teleta. These results establish the feasibility of gene editing in animals like C. teleta, and extend previous work on the development, evolution and function of the C. teleta visual system . Our study represents one example of disruption of animal behaviour by gene editing through CRISPR/CAS9 mutagenesis, and has broad implications for performing genome editing studies in a wide variety of other understudied animals.
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Affiliation(s)
| | | | - E. C. Seaver
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL, 32080USA
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23
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Tsai JW, Kostyleva R, Chen PL, Rivas-Serna IM, Clandinin MT, Meinertzhagen IA, Clandinin TR. Transcriptional Feedback Links Lipid Synthesis to Synaptic Vesicle Pools in Drosophila Photoreceptors. Neuron 2019; 101:721-737.e4. [PMID: 30737130 DOI: 10.1016/j.neuron.2019.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/03/2018] [Accepted: 01/09/2019] [Indexed: 02/06/2023]
Abstract
Neurons can maintain stable synaptic connections across adult life. However, the signals that regulate expression of synaptic proteins in the mature brain are incompletely understood. Here, we describe a transcriptional feedback loop between the biosynthesis and repertoire of specific phospholipids and the synaptic vesicle pool in adult Drosophila photoreceptors. Mutations that disrupt biosynthesis of a subset of phospholipids cause degeneration of the axon terminal and loss of synaptic vesicles. Although degeneration of the axon terminal is dependent on neural activity, activation of sterol regulatory element binding protein (SREBP) is both necessary and sufficient to cause synaptic vesicle loss. Our studies demonstrate that SREBP regulates synaptic vesicle levels by interacting with tetraspanins, critical organizers of membranous organelles. SREBP is an evolutionarily conserved regulator of lipid biosynthesis in non-neuronal cells; our studies reveal a surprising role for this feedback loop in maintaining synaptic vesicle pools in the adult brain.
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Affiliation(s)
- Jessica W Tsai
- Department of Neurobiology, Stanford University, Fairchild D200, 299 W. Campus Drive, Stanford, CA 94305, USA
| | - Ripsik Kostyleva
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Pei-Ling Chen
- Department of Neurobiology, Stanford University, Fairchild D200, 299 W. Campus Drive, Stanford, CA 94305, USA
| | - Irma Magaly Rivas-Serna
- Department of Agriculture, Food, and Nutritional Science, Alberta Institute of Human Nutrition, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - M Thomas Clandinin
- Department of Agriculture, Food, and Nutritional Science, Alberta Institute of Human Nutrition, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Fairchild D200, 299 W. Campus Drive, Stanford, CA 94305, USA.
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24
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Akin O, Bajar BT, Keles MF, Frye MA, Zipursky SL. Cell-type-Specific Patterned Stimulus-Independent Neuronal Activity in the Drosophila Visual System during Synapse Formation. Neuron 2019; 101:894-904.e5. [PMID: 30711355 DOI: 10.1016/j.neuron.2019.01.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/31/2018] [Accepted: 12/28/2018] [Indexed: 12/22/2022]
Abstract
Stereotyped synaptic connections define the neural circuits of the brain. In vertebrates, stimulus-independent activity contributes to neural circuit formation. It is unknown whether this type of activity is a general feature of nervous system development. Here, we report patterned, stimulus-independent neural activity in the Drosophila visual system during synaptogenesis. Using in vivo calcium, voltage, and glutamate imaging, we found that all neurons participate in this spontaneous activity, which is characterized by brain-wide periodic active and silent phases. Glia are active in a complementary pattern. Each of the 15 of over 100 specific neuron types in the fly visual system examined exhibited a unique activity signature. The activity of neurons that are synaptic partners in the adult was highly correlated during development. We propose that this cell-type-specific activity coordinates the development of the functional circuitry of the adult brain.
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Affiliation(s)
- Orkun Akin
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Bryce T Bajar
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Mehmet F Keles
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Mark A Frye
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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25
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Alejevski F, Saint-Charles A, Michard-Vanhée C, Martin B, Galant S, Vasiliauskas D, Rouyer F. The HisCl1 histamine receptor acts in photoreceptors to synchronize Drosophila behavioral rhythms with light-dark cycles. Nat Commun 2019; 10:252. [PMID: 30651542 PMCID: PMC6335465 DOI: 10.1038/s41467-018-08116-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 12/19/2018] [Indexed: 01/09/2023] Open
Abstract
In Drosophila, the clock that controls rest-activity rhythms synchronizes with light-dark cycles through either the blue-light sensitive cryptochrome (Cry) located in most clock neurons, or rhodopsin-expressing histaminergic photoreceptors. Here we show that, in the absence of Cry, each of the two histamine receptors Ort and HisCl1 contribute to entrain the clock whereas no entrainment occurs in the absence of the two receptors. In contrast to Ort, HisCl1 does not restore entrainment when expressed in the optic lobe interneurons. Indeed, HisCl1 is expressed in wild-type photoreceptors and entrainment is strongly impaired in flies with photoreceptors mutant for HisCl1. Rescuing HisCl1 expression in the Rh6-expressing photoreceptors restores entrainment but it does not in other photoreceptors, which send histaminergic inputs to Rh6-expressing photoreceptors. Our results thus show that Rh6-expressing neurons contribute to circadian entrainment as both photoreceptors and interneurons, recalling the dual function of melanopsin-expressing ganglion cells in the mammalian retina.
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Affiliation(s)
- Faredin Alejevski
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Alexandra Saint-Charles
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
- Institut de la Vision, Univ. P. & M. Curie, INSERM, CNRS, Sorbonne Université, Paris, 75012, France
| | - Christine Michard-Vanhée
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Béatrice Martin
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Sonya Galant
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Daniel Vasiliauskas
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - François Rouyer
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France.
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26
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Ebadi H, Perry M, Short K, Klemm K, Desplan C, Stadler PF, Mehta A. Patterning the insect eye: From stochastic to deterministic mechanisms. PLoS Comput Biol 2018; 14:e1006363. [PMID: 30439954 PMCID: PMC6264902 DOI: 10.1371/journal.pcbi.1006363] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 11/29/2018] [Accepted: 07/16/2018] [Indexed: 01/09/2023] Open
Abstract
While most processes in biology are highly deterministic, stochastic mechanisms are sometimes used to increase cellular diversity. In human and Drosophila eyes, photoreceptors sensitive to different wavelengths of light are distributed in stochastic patterns, and one such patterning system has been analyzed in detail in the Drosophila retina. Interestingly, some species in the dipteran family Dolichopodidae (the “long legged” flies, or “Doli”) instead exhibit highly orderly deterministic eye patterns. In these species, alternating columns of ommatidia (unit eyes) produce corneal lenses of different colors. Occasional perturbations in some individuals disrupt the regular columns in a way that suggests that patterning occurs via a posterior-to-anterior signaling relay during development, and that specification follows a local, cellular-automaton-like rule. We hypothesize that the regulatory mechanisms that pattern the eye are largely conserved among flies and that the difference between unordered Drosophila and ordered dolichopodid eyes can be explained in terms of relative strengths of signaling interactions rather than a rewiring of the regulatory network itself. We present a simple stochastic model that is capable of explaining both the stochastic Drosophila eye and the striped pattern of Dolichopodidae eyes and thereby characterize the least number of underlying developmental rules necessary to produce both stochastic and deterministic patterns. We show that only small changes to model parameters are needed to also reproduce intermediate, semi-random patterns observed in another Doli species, and quantification of ommatidial distributions in these eyes suggests that their patterning follows similar rules. A simple model is able to account for a diversity of photoreceptor patterns in different fly species, ranging from highly deterministic to fully random.
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Affiliation(s)
- Haleh Ebadi
- Bioinformatics, Institute for Computer Science, Leipzig University, Leipzig, Germany
- * E-mail:
| | - Michael Perry
- Department of Biology, New York University, New York, New York, United States of America
| | - Keith Short
- Department of Biology, New York University, New York, New York, United States of America
| | - Konstantin Klemm
- Department of Computer Science, School of Science and Technology, Nazarbayev University, Astana, Republic of Kazakhstan
- Instituto de Física Interdisciplinar y Sistemas Complejos, Palma de Mallorca, Spain
| | - Claude Desplan
- Department of Biology, New York University, New York, New York, United States of America
| | - Peter F. Stadler
- Bioinformatics, Institute for Computer Science, Leipzig University, Leipzig, Germany
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Anita Mehta
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
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27
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Stegeman R, Hall H, Escobedo SE, Chang HC, Weake VM. Proper splicing contributes to visual function in the aging Drosophila eye. Aging Cell 2018; 17:e12817. [PMID: 30003673 PMCID: PMC6156539 DOI: 10.1111/acel.12817] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/06/2018] [Accepted: 06/18/2018] [Indexed: 12/19/2022] Open
Abstract
Changes in splicing patterns are a characteristic of the aging transcriptome; however, it is unclear whether these age-related changes in splicing facilitate the progressive functional decline that defines aging. In Drosophila, visual behavior declines with age and correlates with altered gene expression in photoreceptors, including downregulation of genes encoding splicing factors. Here, we characterized the significance of these age-regulated splicing-associated genes in both splicing and visual function. To do this, we identified differential splicing events in either the entire eye or photoreceptors of young and old flies. Intriguingly, aging photoreceptors show differential splicing of a large number of visual function genes. In addition, as shown previously for aging photoreceptors, aging eyes showed increased accumulation of circular RNAs, which result from noncanonical splicing events. To test whether proper splicing was necessary for visual behavior, we knocked down age-regulated splicing factors in photoreceptors in young flies and examined phototaxis. Notably, many of the age-regulated splicing factors tested were necessary for proper visual behavior. In addition, knockdown of individual splicing factors resulted in changes in both alternative splicing at age-spliced genes and increased accumulation of circular RNAs. Together, these data suggest that cumulative decreases in splicing factor expression could contribute to the differential splicing, circular RNA accumulation, and defective visual behavior observed in aging photoreceptors.
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Affiliation(s)
- Rachel Stegeman
- Department of BiochemistryPurdue UniversityWest LafayetteIndiana
- Present address:
University of Minnesota Medical SchoolMinneapolisMinnesota
| | - Hana Hall
- Department of BiochemistryPurdue UniversityWest LafayetteIndiana
| | | | - Henry C. Chang
- Department of Biological SciencesPurdue UniversityWest LafayetteIndiana
| | - Vikki M. Weake
- Department of BiochemistryPurdue UniversityWest LafayetteIndiana
- Purdue University Center for Cancer ResearchPurdue UniversityWest LafayetteIndiana
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28
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Mishra AK, Bernardo-Garcia FJ, Fritsch C, Humberg TH, Egger B, Sprecher SG. Patterning mechanisms diversify neuroepithelial domains in the Drosophila optic placode. PLoS Genet 2018; 14:e1007353. [PMID: 29677185 PMCID: PMC5937791 DOI: 10.1371/journal.pgen.1007353] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 05/07/2018] [Accepted: 04/04/2018] [Indexed: 12/31/2022] Open
Abstract
The central nervous system develops from monolayered neuroepithelial sheets. In a first step patterning mechanisms subdivide the seemingly uniform epithelia into domains allowing an increase of neuronal diversity in a tightly controlled spatial and temporal manner. In Drosophila, neuroepithelial patterning of the embryonic optic placode gives rise to the larval eye primordium, consisting of two photoreceptor (PR) precursor types (primary and secondary), as well as the optic lobe primordium, which during larval and pupal stages develops into the prominent optic ganglia. Here, we characterize a genetic network that regulates the balance between larval eye and optic lobe precursors, as well as between primary and secondary PR precursors. In a first step the proneural factor Atonal (Ato) specifies larval eye precursors, while the orphan nuclear receptor Tailless (Tll) is crucial for the specification of optic lobe precursors. The Hedgehog and Notch signaling pathways act upstream of Ato and Tll to coordinate neural precursor specification in a timely manner. The correct spatial placement of the boundary between Ato and Tll in turn is required to control the precise number of primary and secondary PR precursors. In a second step, Notch signaling also controls a binary cell fate decision, thus, acts at the top of a cascade of transcription factor interactions to define PR subtype identity. Our model serves as an example of how combinatorial action of cell extrinsic and cell intrinsic factors control neural tissue patterning.
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Affiliation(s)
| | | | - Cornelia Fritsch
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | - Boris Egger
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Simon G. Sprecher
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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29
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Collantes-Alegre JM, Mattenberger F, Barberà M, Martínez-Torres D. Characterisation, analysis of expression and localisation of the opsin gene repertoire from the perspective of photoperiodism in the aphid Acyrthosiphon pisum. J Insect Physiol 2018; 104:48-59. [PMID: 29203177 DOI: 10.1016/j.jinsphys.2017.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/19/2017] [Accepted: 11/30/2017] [Indexed: 06/07/2023]
Abstract
Organisms exhibit a wide range of seasonal responses as adaptions to predictable annual changes in their environment. These changes are originally caused by the effect of the Earth's cycles around the sun and its axial tilt. Examples of seasonal responses include floration, migration, reproduction and diapause. In temperate climate zones, the most robust variable to predict seasons is the length of the day (i.e. the photoperiod). The first step to trigger photoperiodic driven responses involves measuring the duration of the light-dark phases, but the molecular clockwork performing this task is poorly characterized. Photopigments such as opsins are known to participate in light perception, being part of the machinery in charge of providing information about the luminous state of the surroundings. Aphids (Hemiptera: Aphididae) are paradigmatic photoperiodic insects, exhibiting a strong induction to diapause when the light regime mimics autumn conditions. The availability of the pea aphid (Acyrthosiphon pisum) genome has facilitated molecular approaches to understand the effect of light stimulus in the photoperiodic induction process. We have identified, experimentally validated and characterized the expression of the full opsin gene repertoire in the pea aphid. Among identified opsin genes in A. pisum, arthropsin is absent in most insects sequenced to date (except for dragonflies and two other hemipterans) but also present in a crustacean, an onychophoran and chelicerates. We have quantified the expression of these genes in aphids exposed to different photoperiodic conditions and at different times of the day and localized their transcripts in the aphid brain. Clear differences in expression patterns were found, thus relating opsin expression with the photoperiodic response.
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Affiliation(s)
- Jorge Mariano Collantes-Alegre
- Institut de Biologia Integrativa de Sistemes, Parc Científic Universitat de València, C/Catedrático José Beltrán n° 2, 46980 Paterna, València, Spain
| | - Florian Mattenberger
- Institut de Biologia Integrativa de Sistemes, Parc Científic Universitat de València, C/Catedrático José Beltrán n° 2, 46980 Paterna, València, Spain; Department of Abiotic Stress, Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain
| | - Miquel Barberà
- Institut de Biologia Integrativa de Sistemes, Parc Científic Universitat de València, C/Catedrático José Beltrán n° 2, 46980 Paterna, València, Spain
| | - David Martínez-Torres
- Institut de Biologia Integrativa de Sistemes, Parc Científic Universitat de València, C/Catedrático José Beltrán n° 2, 46980 Paterna, València, Spain.
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30
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Hope KA, LeDoux MS, Reiter LT. Glial overexpression of Dube3a causes seizures and synaptic impairments in Drosophila concomitant with down regulation of the Na +/K + pump ATPα. Neurobiol Dis 2017; 108:238-248. [PMID: 28888970 PMCID: PMC5675773 DOI: 10.1016/j.nbd.2017.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 12/20/2022] Open
Abstract
Duplication 15q syndrome (Dup15q) is an autism-associated disorder co-incident with high rates of pediatric epilepsy. Additional copies of the E3 ubiquitin ligase UBE3A are thought to cause Dup15q phenotypes, yet models overexpressing UBE3A in neurons have not recapitulated the epilepsy phenotype. We show that Drosophila endogenously expresses Dube3a (fly UBE3A homolog) in glial cells and neurons, prompting an investigation into the consequences of glial Dube3a overexpression. Here we expand on previous work showing that the Na+/K+ pump ATPα is a direct ubiquitin ligase substrate of Dube3a. A robust seizure-like phenotype was observed in flies overexpressing Dube3a in glial cells, but not neurons. Glial-specific knockdown of ATPα also produced seizure-like behavior, and this phenotype was rescued by simultaneously overexpressing ATPα and Dube3a in glia. Our data provides the basis of a paradigm shift in Dup15q research given that clinical phenotypes have long been assumed to be due to neuronal UBE3A overexpression.
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Affiliation(s)
- Kevin A Hope
- Department of Neurology, UTHSC, Memphis, TN, United States; Integrated Biomedical Science Program, UTHSC, Memphis, TN, United States; Department of Anatomy and Neurobiology, UTHSC, Memphis, TN, United States
| | - Mark S LeDoux
- Department of Neurology, UTHSC, Memphis, TN, United States; Department of Anatomy and Neurobiology, UTHSC, Memphis, TN, United States
| | - Lawrence T Reiter
- Department of Neurology, UTHSC, Memphis, TN, United States; Department of Anatomy and Neurobiology, UTHSC, Memphis, TN, United States; Department of Pediatrics, UTHSC, Memphis, TN, United States.
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Abstract
Drosophila atonal (ato) is required for the specification of founding R8 photoreceptors during retinal development. ato is regulated via dual eye-specific enhancers; ato-3’ is subject to initial induction whereas 5’-ato facilitates Notch-mediated autoregulation. Notch is further utilized to induce bHLH repressors of the E(spl) locus to restrict Ato from its initial broad expression to individual cells. Although Notch operates in two, distinct phases, it has remained unclear how the two phases maintain independence from one another. The difference in these two phases has attributed to the hypothesized delayed expression of E(spl). However, immunofluorescence data indicate that E(spl) are expressed during early Ato patterning, suggesting a more sophisticated underlying mechanism. To probe this mechanism, we provide evidence that although E(spl) exert no influence on ato-3’, E(spl) repress 5’-ato and deletion of the E(spl) locus elicits precocious 5’-ato activity. Thus, E(spl) imposes a delay to the timing in which Ato initiates autoregulation. We next sought to understand this finding in the context of E(spl)D, which encodes a dysregulated variant of E(spl)M8 that perturbs R8 patterning, though, as previously reported, only in conjunction with the mutant receptor Nspl. We established a genetic interaction between E(spl)D and roughened eye (roe), a known modulator of Notch signaling in retinogenesis. This link further suggests a dosage-dependence between E(spl) and the proneural activators Ato and Sens, as indicated via interaction assays in which E(spl)D renders aberrant R8 patterning in conjunction with reduced proneural dosage. In total, the biphasicity of Notch signaling relies, to some degree, on the post-translational regulation of individual E(spl) members and, importantly, that post-translational regulation is likely necessary to modulate the level of E(spl) activity throughout the progression of Ato expression.
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Affiliation(s)
- Adam T. Majot
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
| | - Ashok P. Bidwai
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
- * E-mail:
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Speiser DI, Kier WM. New Insights from Genetic Data Sets on the Function and Evolution of Visual Systems: Introduction to a Virtual Symposium in The Biological Bulletin. Biol Bull 2017; 233:1-2. [PMID: 29182500 DOI: 10.1086/695469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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Charlton-Perkins MA, Sendler ED, Buschbeck EK, Cook TA. Multifunctional glial support by Semper cells in the Drosophila retina. PLoS Genet 2017; 13:e1006782. [PMID: 28562601 PMCID: PMC5470715 DOI: 10.1371/journal.pgen.1006782] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 06/14/2017] [Accepted: 04/26/2017] [Indexed: 11/19/2022] Open
Abstract
Glial cells play structural and functional roles central to the formation, activity and integrity of neurons throughout the nervous system. In the retina of vertebrates, the high energetic demand of photoreceptors is sustained in part by Müller glia, an intrinsic, atypical radial glia with features common to many glial subtypes. Accessory and support glial cells also exist in invertebrates, but which cells play this function in the insect retina is largely undefined. Using cell-restricted transcriptome analysis, here we show that the ommatidial cone cells (aka Semper cells) in the Drosophila compound eye are enriched for glial regulators and effectors, including signature characteristics of the vertebrate visual system. In addition, cone cell-targeted gene knockdowns demonstrate that such glia-associated factors are required to support the structural and functional integrity of neighboring photoreceptors. Specifically, we show that distinct support functions (neuronal activity, structural integrity and sustained neurotransmission) can be genetically separated in cone cells by down-regulating transcription factors associated with vertebrate gliogenesis (pros/Prox1, Pax2/5/8, and Oli/Olig1,2, respectively). Further, we find that specific factors critical for glial function in other species are also critical in cone cells to support Drosophila photoreceptor activity. These include ion-transport proteins (Na/K+-ATPase, Eaat1, and Kir4.1-related channels) and metabolic homeostatic factors (dLDH and Glut1). These data define genetically distinct glial signatures in cone/Semper cells that regulate their structural, functional and homeostatic interactions with photoreceptor neurons in the compound eye of Drosophila. In addition to providing a new high-throughput model to study neuron-glia interactions, the fly eye will further help elucidate glial conserved "support networks" between invertebrates and vertebrates. Glia are the caretakers of the nervous system. Like their neighboring neurons, different glial subtypes exist that share many overlapping functions. Despite our recognition of glia as a key component of the brain, the genetic networks that mediate their neuroprotective functions remain relatively poorly understood. Here, using the genetic model Drosophila melanogaster, we identify a new glial cell type in one of the most active tissues in the nervous system—the retina. These cells, called ommatidial cone cells (or Semper cells), were previously recognized for their role in lens formation. Using cell-specific molecular genetic approaches, we demonstrate that cone cells (CCs) also share molecular, functional, and genetic features with both vertebrate and invertebrate glia to prevent light-induced retinal degeneration and provide structural and physiological support for photoreceptors. Further, we demonstrate that three factors associated with gliogenesis in vertebrates—prospero/Prox1, Pax2, and Oli/Olig1,2—control genetically distinct aspects of these support functions. CCs also share molecular and functional features with the three main glial types in the mammalian visual system: Müller glia, astrocytes, and oligodendrocytes. Combined, these studies provide insight into potentially deeply conserved aspects of glial functions in the visual system and introduce a high-throughput system to genetically dissect essential neuroprotective mechanisms.
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Affiliation(s)
- Mark A. Charlton-Perkins
- Department of Pediatrics, Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Edward D. Sendler
- Center of Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Elke K. Buschbeck
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Tiffany A. Cook
- Center of Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Ophthalmology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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Grebler R, Kistenpfennig C, Rieger D, Bentrop J, Schneuwly S, Senthilan PR, Helfrich-Förster C. Drosophila Rhodopsin 7 can partially replace the structural role of Rhodopsin 1, but not its physiological function. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:649-659. [PMID: 28500442 PMCID: PMC5537319 DOI: 10.1007/s00359-017-1182-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 11/25/2022]
Abstract
Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1–6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells. This speaks against a role of Rh7 as photopigment in R1–6, but does not exclude that it works in the inner photoreceptor cells.
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Affiliation(s)
- Rudi Grebler
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Christa Kistenpfennig
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
- Oxitec Ltd, 71 Innovation Drive, Milton Park, Oxford, OX14 4RQ, UK
| | - Dirk Rieger
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Joachim Bentrop
- Cell- and Neurobiology, Zoological Institute, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Stephan Schneuwly
- Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Pingkalai R Senthilan
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany.
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Yasin B, Kohn E, Peters M, Zaguri R, Weiss S, Schopf K, Katz B, Huber A, Minke B. Ectopic Expression of Mouse Melanopsin in Drosophila Photoreceptors Reveals Fast Response Kinetics and Persistent Dark Excitation. J Biol Chem 2017; 292:3624-3636. [PMID: 28119450 PMCID: PMC5339748 DOI: 10.1074/jbc.m116.754770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 01/19/2017] [Indexed: 01/10/2023] Open
Abstract
The intrinsically photosensitive M1 retinal ganglion cells (ipRGC) initiate non-image-forming light-dependent activities and express the melanopsin (OPN4) photopigment. Several features of ipRGC photosensitivity are characteristic of fly photoreceptors. However, the light response kinetics of ipRGC is much slower due to unknown reasons. Here we used transgenic Drosophila, in which the mouse OPN4 replaced the native Rh1 photopigment of Drosophila R1-6 photoreceptors, resulting in deformed rhabdomeric structure. Immunocytochemistry revealed OPN4 expression at the base of the rhabdomeres, mainly at the rhabdomeral stalk. Measurements of the early receptor current, a linear manifestation of photopigment activation, indicated large expression of OPN4 in the plasma membrane. Comparing the early receptor current amplitude and action spectra between WT and the Opn4-expressing Drosophila further indicated that large quantities of a blue absorbing photopigment were expressed, having a dark stable blue intermediate state. Strikingly, the light-induced current of the Opn4-expressing fly photoreceptors was ∼40-fold faster than that of ipRGC. Furthermore, an intense white flash induced a small amplitude prolonged dark current composed of discrete unitary currents similar to the Drosophila single photon responses. The induction of prolonged dark currents by intense blue light could be suppressed by a following intense green light, suggesting induction and suppression of prolonged depolarizing afterpotential. This is the first demonstration of heterologous functional expression of mammalian OPN4 in the genetically emendable Drosophila photoreceptors. Moreover, the fast OPN4-activated ionic current of Drosophila photoreceptors relative to that of mouse ipRGC, indicates that the slow light response of ipRGC does not arise from an intrinsic property of melanopsin.
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Affiliation(s)
- Bushra Yasin
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Elkana Kohn
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Maximilian Peters
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Rachel Zaguri
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Shirley Weiss
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Krystina Schopf
- the Department of Biosensorics, Institute of Physiology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Ben Katz
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
| | - Armin Huber
- the Department of Biosensorics, Institute of Physiology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Baruch Minke
- From the Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC) and the Edmond and Lily Safra Center for Brain Sciences (ELSC), Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel and
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Bandyopadhyay M, Bishop CP, Bidwai AP. The Conserved MAPK Site in E(spl)-M8, an Effector of Drosophila Notch Signaling, Controls Repressor Activity during Eye Development. PLoS One 2016; 11:e0159508. [PMID: 27428327 PMCID: PMC4948772 DOI: 10.1371/journal.pone.0159508] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/05/2016] [Indexed: 12/12/2022] Open
Abstract
The specification of patterned R8 photoreceptors at the onset of eye development depends on timely inhibition of Atonal (Ato) by the Enhancer of split (E(spl) repressors. Repression of Ato by E(spl)-M8 requires the kinase CK2 and is inhibited by the phosphatase PP2A. The region targeted by CK2 harbors additional conserved Ser residues, raising the prospect of regulation via multi-site phosphorylation. Here we investigate one such motif that meets the consensus for modification by MAPK, a well-known effector of Epidermal Growth Factor Receptor (EGFR) signaling. Our studies reveal an important role for the predicted MAPK site of M8 during R8 birth. Ala/Asp mutations reveal that the CK2 and MAPK sites ensure that M8 repression of Ato and the R8 fate occurs in a timely manner and at a specific stage (stage-2/3) of the morphogenetic furrow (MF). M8 repression of Ato is mitigated by halved EGFR dosage, and this effect requires an intact MAPK site. Accordingly, variants with a phosphomimetic Asp at the MAPK site exhibit earlier (inappropriate) activity against Ato even at stage-1 of the MF, where a positive feedback-loop is necessary to raise Ato levels to a threshold sufficient for the R8 fate. Analysis of deletion variants reveals that both kinase sites (CK2 and MAPK) contribute to ‘cis’-inhibition of M8. This key regulation by CK2 and MAPK is bypassed by the E(spl)D mutation encoding the truncated protein M8*, which potently inhibits Ato at stage-1 of R8 birth. We also provide evidence that PP2A likely targets the MAPK site. Thus multi-site phosphorylation controls timely onset of M8 repressor activity in the eye, a regulation that appears to be dispensable in the bristle. The high conservation of the CK2 and MAPK sites in the insect E(spl) proteins M7, M5 and Mγ, and their mammalian homologue HES6, suggest that this mode of regulation may enable E(spl)/HES proteins to orchestrate repression by distinct tissue-specific mechanisms, and is likely to have broader applicability than has been previously recognized.
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Affiliation(s)
- Mohna Bandyopadhyay
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
| | - Clifton P. Bishop
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
| | - Ashok P. Bidwai
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
- * E-mail:
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Mavromatakis YE, Tomlinson A. R7 Photoreceptor Specification in the Developing Drosophila Eye: The Role of the Transcription Factor Deadpan. PLoS Genet 2016; 12:e1006159. [PMID: 27427987 PMCID: PMC4948816 DOI: 10.1371/journal.pgen.1006159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/10/2016] [Indexed: 02/02/2023] Open
Abstract
As cells proceed along their developmental pathways they make a series of sequential cell fate decisions. Each of those decisions needs to be made in a robust manner so there is no ambiguity in the state of the cell as it proceeds to the next stage. Here we examine the decision made by the Drosophila R7 precursor cell to become a photoreceptor and ask how the robustness of that decision is achieved. The transcription factor Tramtrack (Ttk) inhibits photoreceptor assignment, and previous studies found that the RTK-induced degradation of Ttk was critically required for R7 specification. Here we find that the transcription factor Deadpan (Dpn) is also required; it is needed to silence ttk transcription, and only when Ttk protein degradation and transcriptional silencing occur together is the photoreceptor fate robustly achieved. Dpn expression needs to be tightly restricted to R7 precursors, and we describe the role played by Ttk in repressing dpn transcription. Thus, Dpn and Ttk act as mutually repressive transcription factors, with Dpn acting to ensure that Ttk is effectively removed from R7, and Ttk acting to prevent Dpn expression in other cells. Furthermore, we find that N activity is required to promote dpn transcription, and only in R7 precursors does the removal of Ttk coincide with high N activity, and only in this cell does Dpn expression result. Animals are made from a vast diversity of different cell types, and understanding how they are specified is a major goal of developmental biology. In this study we use the Drosophila R7 photoreceptor as a model system for understanding how cell fate specification occurs. We examine the step when the R7 precursor cell adopts the photoreceptor fate, and ask how the signaling pathways active in the cell are integrated to provide an unambiguous directive to become a photoreceptor. The transcription factor Tramtrack (Ttk) represses the ability of the cell to become a photoreceptor, and how it is removed is the focus of this study. Previous work identified a protein degradation mechanism, and here we describe the role of the transcription factor Deadpan (Dpn) in repressing ttk transcription. We find that both the protein degradation mechanism and transcriptional silencing are required for efficient Ttk removal. Dpn expression needs to be restricted to the R7 precursor and we describe how the mutual antagonism between Ttk and Dpn and the action of the Notch signaling pathway are integrated to ensure that Dpn is selectively expressed in the cell.
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Affiliation(s)
- Yannis Emmanuel Mavromatakis
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Andrew Tomlinson
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
- * E-mail:
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Sehadová H, Markova EP, Sehnal F, Takeda M. Distribution of Circadian Clock-Related Proteins in the Cephalic Nervous System of the Silkworm, Bombyx Mori. J Biol Rhythms 2016; 19:466-82. [PMID: 15523109 DOI: 10.1177/0748730404269153] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In the circadian timing systems, input pathways transmit information on the diurnal environmental changes to a core oscillator that generates signals relayed to the body periphery by output pathways. Cryptochrome (CRY) protein participates in the light perception; period (PER), Cycle (CYC), and Doubletime (DBT) proteins drive the core oscillator; and arylalkylamines are crucial for the clock output in vertebrates. Using antibodies to CRY, PER, CYC, DBT, and arylalkylamine N-acetyltransferase (aaNAT), the authors examined neuronal architecture of the circadian system in the cephalic ganglia of adult silkworms. The antibodies reacted in the cytoplasm, never in the nuclei, of specific neurons. Acluster of 4 large Ia1 neurons in each dorsolateral protocerebrum, a pair of cells in the frontal ganglion, and nerve fibers in the corpora cardiaca and corpora allata were stained with all antibodies. The intensity of PER staining in the Ia1 cells and in 2 to 4 adjacent small cells oscillated, being maximal late in subjective day and minimal in early night. No other oscillations were detected in any cell and with any antibody. Six small cells in close vicinity to the Ia1 neurons coexpressed CYC-like and DBT-like, and 4 to 5 of them also coexpressed aaNATlike immunoreactivity; the PER- and CRY-like antigens were each present in separate groups of 4 cells. The CYC- and aaNAT-like antigens were further colocalized in small groups of neurons in the pars intercerebralis, at the venter of the optic tract, and in the subesophageal ganglion. Remaining antibodies reacted with similarly positioned cells in the pars intercerebralis, and the DBT antibody also reacted with the cells in the subesophageal ganglion, but antigen colocalizations were not proven. The results imply that key components of the silkworm circadian system reside in the Ia1 neurons and that additional, hierarchically arranged oscillators contribute to overt pacemaking. The retrocerebral neurohemal organs seem to serve as outlets transmitting central neural oscillations to the hemolymph. The frontal ganglion may play an autonomous function in circadian regulations. The colocalization of aaNAT- and CYC-like antigens suggests that the enzyme is functionally linked to CYC as in vertebrates and that arylalkylamines are involved in the insect output pathway.
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Affiliation(s)
- Hana Sehadová
- Division of Molecular Science, Graduate School of Science and Technology, Kobe University, Japan
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39
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Abstract
Among the five photoreceptor opsins in the eye of Drosophila, Rhodopsin 1 (Rh1) is expressed in the six outer photoreceptors. In a previous study that combined behavioral genetics with computational modeling, we demonstrated that flies can use the signals from Rh1 for color vision. Here, we provide an in-depth computational analysis of wildtype Drosophila wavelength discrimination specifically considering the consequences of different choices of computations in the preprocessing of the behavioral data. The results support the conclusion that Drosophila wavelength discrimination behavior can best be explained by a contribution of Rh1. These findings are corroborated by results of an information-theoretical analysis that shows that Rh1 provides information for discrimination of natural reflectance spectra.
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Affiliation(s)
- Christian Garbers
- Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany and Bernstein Center for Computational Neuroscience Munich, Munich, Germany
| | - Thomas Wachtler
- Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany and Bernstein Center for Computational Neuroscience Munich, Munich, Germany
- * E-mail:
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40
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Glantz ST, Carpenter EJ, Melkonian M, Gardner KH, Boyden ES, Wong GKS, Chow BY. Functional and topological diversity of LOV domain photoreceptors. Proc Natl Acad Sci U S A 2016; 113:E1442-51. [PMID: 26929367 PMCID: PMC4801262 DOI: 10.1073/pnas.1509428113] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Light-oxygen-voltage sensitive (LOV) flavoproteins are ubiquitous photoreceptors that mediate responses to environmental cues. Photosensory inputs are transduced into signaling outputs via structural rearrangements in sensor domains that consequently modulate the activity of an effector domain or multidomain clusters. Establishing the diversity in effector function and sensor-effector topology will inform what signaling mechanisms govern light-responsive behaviors across multiple kingdoms of life and how these signals are transduced. Here, we report the bioinformatics identification of over 6,700 candidate LOV domains (including over 4,000 previously unidentified sequences from plants and protists), and insights from their annotations for ontological function and structural arrangements. Motif analysis identified the sensors from ∼42 million ORFs, with strong statistical separation from other flavoproteins and non-LOV members of the structurally related Per-aryl hydrocarbon receptor nuclear translocator (ARNT)-Sim family. Conserved-domain analysis determined putative light-regulated function and multidomain topologies. We found that for certain effectors, sensor-effector linker length is discretized based on both phylogeny and the preservation of α-helical heptad repeats within an extended coiled-coil linker structure. This finding suggests that preserving sensor-effector orientation is a key determinant of linker length, in addition to ancestry, in LOV signaling structure-function. We found a surprisingly high prevalence of effectors with functions previously thought to be rare among LOV proteins, such as regulators of G protein signaling, and discovered several previously unidentified effectors, such as lipases. This work highlights the value of applying genomic and transcriptomic technologies to diverse organisms to capture the structural and functional variation in photosensory proteins that are vastly important in adaptation, photobiology, and optogenetics.
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Affiliation(s)
- Spencer T Glantz
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Eric J Carpenter
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Michael Melkonian
- Institute of Botany, Cologne Biocenter, University of Cologne, 50674 Cologne, Germany
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, City College of New York, New York, NY 10031; Department of Chemistry and Biochemistry, City College of New York, New York, NY 10031; Biochemistry, Chemistry and Biology Programs, Graduate Center, The City University of New York, New York, NY 10031
| | - Edward S Boyden
- The Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139; McGovern Institute for Brain Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9; Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2E1; BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen 518083, China
| | - Brian Y Chow
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104;
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Iwanami N, Nakamura Y, Satoh T, Liu Z, Satoh AK. Rab6 Is Required for Multiple Apical Transport Pathways but Not the Basolateral Transport Pathway in Drosophila Photoreceptors. PLoS Genet 2016; 12:e1005828. [PMID: 26890939 PMCID: PMC4758697 DOI: 10.1371/journal.pgen.1005828] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 01/05/2016] [Indexed: 11/30/2022] Open
Abstract
Polarized membrane trafficking is essential for the construction and maintenance of multiple plasma membrane domains of cells. Highly polarized Drosophila photoreceptors are an excellent model for studying polarized transport. A single cross-section of Drosophila retina contains many photoreceptors with 3 clearly differentiated plasma membrane domains: a rhabdomere, stalk, and basolateral membrane. Genome-wide high-throughput ethyl methanesulfonate screening followed by precise immunohistochemical analysis identified a mutant with a rare phenotype characterized by a loss of 2 apical transport pathways with normal basolateral transport. Rapid gene identification using whole-genome resequencing and single nucleotide polymorphism mapping identified a nonsense mutation of Rab6 responsible for the apical-specific transport deficiency. Detailed analysis of the trafficking of a major rhabdomere protein Rh1 using blue light-induced chromophore supply identified Rab6 as essential for Rh1 to exit the Golgi units. Rab6 is mostly distributed from the trans-Golgi network to a Golgi-associated Rab11-positive compartment that likely recycles endosomes or transport vesicles going to recycling endosomes. Furthermore, the Rab6 effector, Rich, is required for Rab6 recruitment in the trans-Golgi network. Moreover, a Rich null mutation phenocopies the Rab6 null mutant, indicating that Rich functions as a guanine nucleotide exchange factor for Rab6. The results collectively indicate that Rab6 and Rich are essential for the trans-Golgi network–recycling endosome transport of cargoes destined for 2 apical domains. However, basolateral cargos are sorted and exported from the trans-Golgi network in a Rab6-independent manner. Cells in animal bodies have multiple plasma membrane domains; this polarized characteristic of cells is essential for their specific functions. Selective membrane transport pathways play key roles in the construction and maintenance of polarized structures. Drosophila photoreceptors with multiple plasma membrane domains are an excellent model of polarized transport. We performed genetic screening and identified a Rab6 null mutant with a rare phenotype characterized by a loss of 2 apical transport pathways with normal basolateral transport. Although Rab6 functions in the Golgi are well known, its function in polarized transport was unexpected. Here, we found that Rab6 and its effector, Rich, are required for multiple apical transport pathways but not the basolateral transport pathway. Our findings strongly indicate that the membrane proteins delivered to multiple polarized domains are not sorted simultaneously: basolateral cargos are segregated before the Rab6-dependent process, and cargos going to multiple apical domains are sorted after Rab6-dependent transport from the trans-Golgi network to the Golgi-associated Rab11-positive compartment, which presumably recycles endosomes. Our finding of the function of Rab6 in polarized transport will elucidate the molecular mechanisms of polarized transport.
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Affiliation(s)
- Nozomi Iwanami
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yuri Nakamura
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Takunori Satoh
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Ziguang Liu
- Institute of Animal Husbandry, Heilongjiang Academy of Agricultural Sciences, Harbin, Heilongjiang, China
| | - Akiko K. Satoh
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
- * E-mail:
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Satoh T, Satoh AK. [EMC is essential for biosynthesis of rhodopsin and other multipass membrane proteins in Drosophila photoreceptors]. Seikagaku 2015; 87:781-784. [PMID: 26863762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Ramirez J, Martinez A, Lectez B, Lee SY, Franco M, Barrio R, Dittmar G, Mayor U. Proteomic Analysis of the Ubiquitin Landscape in the Drosophila Embryonic Nervous System and the Adult Photoreceptor Cells. PLoS One 2015; 10:e0139083. [PMID: 26460970 PMCID: PMC4604154 DOI: 10.1371/journal.pone.0139083] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/09/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Ubiquitination is known to regulate physiological neuronal functions as well as to be involved in a number of neuronal diseases. Several ubiquitin proteomic approaches have been developed during the last decade but, as they have been mostly applied to non-neuronal cell culture, very little is yet known about neuronal ubiquitination pathways in vivo. METHODOLOGY/PRINCIPAL FINDINGS Using an in vivo biotinylation strategy we have isolated and identified the ubiquitinated proteome in neurons both for the developing embryonic brain and for the adult eye of Drosophila melanogaster. Bioinformatic comparison of both datasets indicates a significant difference on the ubiquitin substrates, which logically correlates with the processes that are most active at each of the developmental stages. Detection within the isolated material of two ubiquitin E3 ligases, Parkin and Ube3a, indicates their ubiquitinating activity on the studied tissues. Further identification of the proteins that do accumulate upon interference with the proteasomal degradative pathway provides an indication of the proteins that are targeted for clearance in neurons. Last, we report the proof-of-principle validation of two lysine residues required for nSyb ubiquitination. CONCLUSIONS/SIGNIFICANCE These data cast light on the differential and common ubiquitination pathways between the embryonic and adult neurons, and hence will contribute to the understanding of the mechanisms by which neuronal function is regulated. The in vivo biotinylation methodology described here complements other approaches for ubiquitome study and offers unique advantages, and is poised to provide further insight into disease mechanisms related to the ubiquitin proteasome system.
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Affiliation(s)
- Juanma Ramirez
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Aitor Martinez
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Benoit Lectez
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Mollecular Cell Biology, Turku Centre for Biotechnology, Turku, Finland
| | - So Young Lee
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Maribel Franco
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Developmental Neurobiology, Institute of Neurosciences, CSIC/UMH, Sant Joan d’Alacant, Alicante, Spain
| | - Rosa Barrio
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Gunnar Dittmar
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ugo Mayor
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia, Spain
- * E-mail:
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Zhang T, Du W. Groucho restricts rhomboid expression and couples EGFR activation with R8 selection during Drosophila photoreceptor differentiation. Dev Biol 2015; 407:246-55. [PMID: 26417727 DOI: 10.1016/j.ydbio.2015.09.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/18/2015] [Accepted: 09/24/2015] [Indexed: 11/17/2022]
Abstract
Notch and EGFR signaling pathways play important roles in photoreceptor differentiation during Drosophila eye development. Notch signaling induces Enhancer of Split (E(spl)) proteins to repress atonal (ato) expression and restrict R8 photoreceptor cell fate. The R8 precursors express rhomboid (rho), which is required for the release of active EGFR ligand to activate EGFR signaling in surrounding cells for the subsequent stepwise recruitment. However, it is not clear about the mechanisms of transcriptional regulation of rho and how the lateral inhibition of Notch signaling and rho expression are coordinated. In this study, we show that inactivation of Groucho (Gro), an evolutionally conserved transcriptional corepressor, inhibits Ato upregulation, delays R8 determination, and promotes differentiation of R2-5 type of neurons. We demonstrate that these phenotypes are caused by a combination of the loss of Notch-mediated lateral inhibition and the precocious activation of EGFR signaling due to deregulated rho expression. Blocking EGFR signaling by Pnt-RNAi in conjunction with Gro-inactivation leads to lateral inhibition defects with deregulated Ato expression and R8 differentiation. We further show that inactivation of E(spl), which are the Gro binding transcription factors, causes deregulated rho expression and extra R8 cells within and posterior to the morphogenetic furrow (MF), and that E(spl) mediates the binding of Gro to the regulatory regions of both rho and ato genes in eye disc cells. Our results suggest that Gro inhibits rho expression in undifferentiated cells and represses the expression of both ato and rho in non-R8 precursors during initiation of photoreceptor differentiation in an E(spl)-dependent manner. The latter function of Gro provides novel insights into the mechanism that coordinates R8 specification with the restriction of initial rho expression to developing R8 cells.
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Affiliation(s)
- Tianyi Zhang
- Ben May Department for Cancer Research, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA
| | - Wei Du
- Ben May Department for Cancer Research, The University of Chicago, 929 E. 57th Street, Chicago, IL 60637, USA.
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Mencarelli C, Pichaud F. Orthodenticle Is Required for the Expression of Principal Recognition Molecules That Control Axon Targeting in the Drosophila Retina. PLoS Genet 2015; 11:e1005303. [PMID: 26114289 PMCID: PMC4482733 DOI: 10.1371/journal.pgen.1005303] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/27/2015] [Indexed: 11/18/2022] Open
Abstract
Parallel processing of neuronal inputs relies on assembling neural circuits into distinct synaptic-columns and layers. This is orchestrated by matching recognition molecules between afferent growth cones and target areas. Controlling the expression of these molecules during development is crucial but not well understood. The developing Drosophila visual system is a powerful genetic model for addressing this question. In this model system, the achromatic R1-6 photoreceptors project their axons in the lamina while the R7 and R8 photoreceptors, which are involved in colour detection, project their axons to two distinct synaptic-layers in the medulla. Here we show that the conserved homeodomain transcription factor Orthodenticle (Otd), which in the eye is a main regulator of rhodopsin expression, is also required for R1-6 photoreceptor synaptic-column specific innervation of the lamina. Our data indicate that otd function in these photoreceptors is largely mediated by the recognition molecules flamingo (fmi) and golden goal (gogo). In addition, we find that otd regulates synaptic-layer targeting of R8. We demonstrate that during this process, otd and the R8-specific transcription factor senseless/Gfi1 (sens) function as independent transcriptional inputs that are required for the expression of fmi, gogo and the adhesion molecule capricious (caps), which govern R8 synaptic-layer targeting. Our work therefore demonstrates that otd is a main component of the gene regulatory network that regulates synaptic-column and layer targeting in the fly visual system. Establishing neural circuits during brain development relies on the ability for neurons to find their appropriate targets, a task that depends on recognition molecules whose expression must be tightly controlled. Very little is known of the factors that control the expression of these molecules. Here we have used the genetically amenable fly retina to address this issue. We identify Orthodenticle, a protein involved in mammalian brain development, as a main component of a new genetic cascade controlling the expression of recognition molecules that govern the wiring of the fly retina. Our work raises the issue that Orthodenticle might play a similar role in mammals. It also sheds new light on the genetic basis for wiring a model neural circuit during development.
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Affiliation(s)
- Chiara Mencarelli
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Franck Pichaud
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- * E-mail:
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Wernet MF, Perry MW, Desplan C. The evolutionary diversity of insect retinal mosaics: common design principles and emerging molecular logic. Trends Genet 2015; 31:316-28. [PMID: 26025917 PMCID: PMC4458154 DOI: 10.1016/j.tig.2015.04.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 04/13/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022]
Abstract
Independent evolution has resulted in a vast diversity of eyes. Despite the lack of a common Bauplan or ancestral structure, similar developmental strategies are used. For instance, different classes of photoreceptor cells (PRs) are distributed stochastically and/or localized in different regions of the retina. Here, we focus on recent progress made towards understanding the molecular principles behind patterning retinal mosaics of insects, one of the most diverse groups of animals adapted to life on land, in the air, under water, or on the water surface. Morphological, physiological, and behavioral studies from many species provide detailed descriptions of the vast variation in retinal design and function. By integrating this knowledge with recent progress in the characterization of insect Rhodopsins as well as insight from the model organism Drosophila melanogaster, we seek to identify the molecular logic behind the adaptation of retinal mosaics to the habitat and way of life of an animal.
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Affiliation(s)
- Mathias F Wernet
- New York University Abu Dhabi, Abu Dhabi, 129188 Saadiyat Island, United Arab Emirates
| | - Michael W Perry
- Department of Biology, New York University, New York, NY 10003, USA
| | - Claude Desplan
- New York University Abu Dhabi, Abu Dhabi, 129188 Saadiyat Island, United Arab Emirates; Department of Biology, New York University, New York, NY 10003, USA.
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Lee YM, Sun YH. Maintenance of glia in the optic lamina is mediated by EGFR signaling by photoreceptors in adult Drosophila. PLoS Genet 2015; 11:e1005187. [PMID: 25909451 PMCID: PMC4409299 DOI: 10.1371/journal.pgen.1005187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/31/2015] [Indexed: 01/13/2023] Open
Abstract
The late onset of neurodegeneration in humans indicates that the survival and function of cells in the nervous system must be maintained throughout adulthood. In the optic lamina of the adult Drosophila, the photoreceptor axons are surrounded by multiple types of glia. We demonstrated that the adult photoreceptors actively contribute to glia maintenance in their target field within the optic lamina. This effect is dependent on the epidermal growth factor receptor (EGFR) ligands produced by the R1-6 photoreceptors and transported to the optic lamina to act on EGFR in the lamina glia. EGFR signaling is necessary and sufficient to act in a cell-autonomous manner in the lamina glia. Our results suggest that EGFR signaling is required for the trafficking of the autophagosome/endosome to the lysosome. The loss of EGFR signaling results in cell degeneration most likely because of the accumulation of autophagosomes. Our findings provide in vivo evidence for the role of adult neurons in the maintenance of glia and a novel role for EGFR signaling in the autophagic flux. Degeneration of the nervous system can be viewed as a failure to maintain cell survival or function in the nervous system. The late onset of neurodegeneration in humans indicates that the cell survival in the nervous system must be maintained throughout our lives. Neuronal survival is maintained by neurotrophic factors in adults; however, it is unclear whether glia survival is also maintained throughout adulthood. Here, we use the Drosophila visual system as a model to address the role played by adult neurons for the active maintenance of glia. We demonstrated that the adult photoreceptors secrete a signaling molecule, which is transported to the brain to act on the lamina glia and maintain its integrity. When this signaling pathway is blocked, the lamina glia undergoes a progressive and irreversible degeneration. The primary defect occurs in the trafficking from the late endosome and autophagosome to the lysosome. This defect leads to an accumulation of autophagosomes and subsequent cell degeneration as a result of autophagy. Our findings provide in vivo evidence for a novel aspect of the neuron-glia interaction and a novel role for EGFR signaling in regulating the maintenance and degeneration of the nervous system.
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Affiliation(s)
- Yuan-Ming Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Y. Henry Sun
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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Battelle BA, Kempler KE, Saraf SR, Marten CE, Dugger DR, Speiser DI, Oakley TH. Opsins in Limulus eyes: characterization of three visible light-sensitive opsins unique to and co-expressed in median eye photoreceptors and a peropsin/RGR that is expressed in all eyes. J Exp Biol 2015; 218:466-79. [PMID: 25524988 PMCID: PMC4317242 DOI: 10.1242/jeb.116087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
The eyes of the horseshoe crab Limulus polyphemus have long been used for studies of basic mechanisms of vision, and the structure and physiology of Limulus photoreceptors have been examined in detail. Less is known about the opsins Limulus photoreceptors express. We previously characterized a UV opsin (LpUVOps1) that is expressed in all three types of Limulus eyes (lateral compound eyes, median ocelli and larval eyes) and three visible light-sensitive rhabdomeric opsins (LpOps1, -2 and -5) that are expressed in Limulus lateral compound and larval eyes. Physiological studies showed that visible light-sensitive photoreceptors are also present in median ocelli, but the visible light-sensitive opsins they express were unknown. In the current study we characterize three newly identified, visible light-sensitive rhabdomeric opsins (LpOps6, -7 and -8) that are expressed in median ocelli. We show that they are ocellar specific and that all three are co-expressed in photoreceptors distinct from those expressing LpUVOps1. Our current findings show that the pattern of opsin expression in Limulus eyes is much more complex than previously thought and extend our previous observations of opsin co-expression in visible light-sensitive Limulus photoreceptors. We also characterize a Limulus peropsin/RGR (LpPerOps1). We examine the phylogenetic relationship of LpPerOps1 with other peropsins and RGRs, demonstrate that LpPerOps1 transcripts are expressed in each of the three types of Limulus eyes and show that the encoded protein is expressed in membranes of cells closely associated with photoreceptors in each eye type. These finding suggest that peropsin was in the opsin repertoire of euchelicerates.
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Affiliation(s)
- Barbara-Anne Battelle
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Karen E Kempler
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Spencer R Saraf
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Catherine E Marten
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Donald R Dugger
- Department of Ophthalmology, University of Florida, Gainesville, FL 32080, USA
| | - Daniel I Speiser
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Todd H Oakley
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA
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Rosenbaum EE, Vasiljevic E, Cleland SC, Flores C, Colley NJ. The Gos28 SNARE protein mediates intra-Golgi transport of rhodopsin and is required for photoreceptor survival. J Biol Chem 2014; 289:32392-409. [PMID: 25261468 PMCID: PMC4239595 DOI: 10.1074/jbc.m114.585166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/24/2014] [Indexed: 11/06/2022] Open
Abstract
SNARE proteins play indispensable roles in membrane fusion events in many cellular processes, including synaptic transmission and protein trafficking. Here, we characterize the Golgi SNARE protein, Gos28, and its role in rhodopsin (Rh1) transport through Drosophila photoreceptors. Mutations in gos28 lead to defective Rh1 trafficking and retinal degeneration. We have pinpointed a role for Gos28 in the intra-Golgi transport of Rh1, downstream from α-mannosidase-II in the medial- Golgi. We have confirmed the necessity of key residues in Gos28's SNARE motif and demonstrate that its transmembrane domain is not required for vesicle fusion, consistent with Gos28 functioning as a t-SNARE for Rh1 transport. Finally, we show that human Gos28 rescues both the Rh1 trafficking defects and retinal degeneration in Drosophila gos28 mutants, demonstrating the functional conservation of these proteins. Our results identify Gos28 as an essential SNARE protein in Drosophila photoreceptors and provide mechanistic insights into the role of SNAREs in neurodegenerative disease.
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Affiliation(s)
- Erica E Rosenbaum
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Eva Vasiljevic
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Spencer C Cleland
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Carlos Flores
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Nansi Jo Colley
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
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Kannan R, Kuzina I, Wincovitch S, Nowotarski SH, Giniger E. The Abl/enabled signaling pathway regulates Golgi architecture in Drosophila photoreceptor neurons. Mol Biol Cell 2014; 25:2993-3005. [PMID: 25103244 PMCID: PMC4230588 DOI: 10.1091/mbc.e14-02-0729] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 06/04/2014] [Accepted: 07/29/2014] [Indexed: 11/24/2022] Open
Abstract
The Golgi apparatus is optimized separately in different tissues for efficient protein trafficking, but we know little of how cell signaling shapes this organelle. We now find that the Abl tyrosine kinase signaling pathway controls the architecture of the Golgi complex in Drosophila photoreceptor (PR) neurons. The Abl effector, Enabled (Ena), selectively labels the cis-Golgi in developing PRs. Overexpression or loss of function of Ena increases the number of cis- and trans-Golgi cisternae per cell, and Ena overexpression also redistributes Golgi to the most basal portion of the cell soma. Loss of Abl or its upstream regulator, the adaptor protein Disabled, lead to the same alterations of Golgi as does overexpression of Ena. The increase in Golgi number in Abl mutants arises in part from increased frequency of Golgi fission events and a decrease in fusions, as revealed by live imaging. Finally, we demonstrate that the effects of Abl signaling on Golgi are mediated via regulation of the actin cytoskeleton. Together, these data reveal a direct link between cell signaling and Golgi architecture. Moreover, they raise the possibility that some of the effects of Abl signaling may arise, in part, from alterations of protein trafficking and secretion.
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Affiliation(s)
- Ramakrishnan Kannan
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Irina Kuzina
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Stephen Wincovitch
- Cytogenetics and Microscopy Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Stephanie H Nowotarski
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Edward Giniger
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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