1
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Loh YM, Xu YY, Lee TT, Ohashi TS, Zhang YD, Eberl DF, Su MP, Kamikouchi A. Differences in male Aedes aegypti and Aedes albopictus hearing systems facilitate recognition of conspecific female flight tones. iScience 2024; 27:110264. [PMID: 39027372 PMCID: PMC11255862 DOI: 10.1016/j.isci.2024.110264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/18/2024] [Accepted: 06/06/2024] [Indexed: 07/20/2024] Open
Abstract
When Aedes albopictus mosquitoes invade regions predominated by Aedes aegypti, either the latter can be displaced or the species can coexist, with potential consequences on disease transmission. Males from both species identify females by listening for her flight sounds. Comparing male hearing systems may provide insight into how hearing could prevent interspecific mating. Here, we show that species-specific differences in female wing beat frequencies are reflected in differences in male ear mechanical tuning frequencies and sound response profiles. Though Aedes albopictus males are attracted to sound, they do not readily display abdominal bending, unlike Aedes aegypti. We observed interspecific differences in male ear mechanical, but not electrical, tuning, suggesting a conserved primary auditory processing pathway. Our work suggests a potential role for hearing in the premating isolation of Aedes aegypti and Aedes albopictus, with implications for predicting future dynamics in their sympatric relationships and our understanding of mosquito acoustic communication.
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Affiliation(s)
- YuMin M. Loh
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Yifeng Y.J. Xu
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Tai-Ting Lee
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Takuro S. Ohashi
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Yixiao D. Zhang
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Daniel F. Eberl
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Matthew P. Su
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
- Institute for Advanced Research, Nagoya University, Nagoya, Japan
| | - Azusa Kamikouchi
- Graduate School of Science, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
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2
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Dolezal DM, Joiner MLA, Eberl DF. Two distinct functions of Lim1 in the Drosophila antenna. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001229. [PMID: 38957438 PMCID: PMC11217802 DOI: 10.17912/micropub.biology.001229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/14/2024] [Accepted: 06/14/2024] [Indexed: 07/04/2024]
Abstract
The Lim1 transcription factor is required in Drosophila for patterning the eye-antennal disk. At the adult stage, Lim1 is strongly expressed in Johnston's Organ (JO) neurons, the antennal auditory organ. Using RNAi-mediated knockdown of Lim1 using a strong neuronal driver, we find a significant reduction in electrophysiological responses to auditory stimuli, recorded from the antennal nerve. This reduction can be accounted for by Lim1 knockdown in the auditory subset of JO neurons, with no effect of knockdown in JO neuron subsets associated with wind or gravity detection. Conversely, Lim1 knockdown in JO sense organ precursors had no effect on hearing. Mosaic animals with antennal clones of the Lim1 E9 null mutation showed morphological defects in the antenna, and significant auditory electrophysiological defects. Our results are consistent with two distinct functions for Lim1 in the antenna, including an early patterning function in the eye-antennal disk, and a later neural differentiation function in the JO neurons.
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Affiliation(s)
| | | | - Daniel F Eberl
- Biology, University of Iowa, Iowa City, Iowa, United States
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3
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Sutton DC, Andrews JC, Dolezal DM, Park YJ, Li H, Eberl DF, Yamamoto S, Groves AK. Comparative exploration of mammalian deafness gene homologues in the Drosophila auditory organ shows genetic correlation between insect and vertebrate hearing. PLoS One 2024; 19:e0297846. [PMID: 38412189 PMCID: PMC10898740 DOI: 10.1371/journal.pone.0297846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 01/13/2024] [Indexed: 02/29/2024] Open
Abstract
Johnston's organ, the Drosophila auditory organ, is anatomically very different from the mammalian organ of Corti. However, recent evidence indicates significant cellular and molecular similarities exist between vertebrate and invertebrate hearing, suggesting that Drosophila may be a useful platform to determine the function of the many mammalian deafness genes whose underlying biological mechanisms are poorly characterized. Our goal was a comprehensive screen of all known orthologues of mammalian deafness genes in the fruit fly to better understand conservation of hearing mechanisms between the insect and the fly and ultimately gain insight into human hereditary deafness. We used bioinformatic comparisons to screen previously reported human and mouse deafness genes and found that 156 of them have orthologues in Drosophila melanogaster. We used fluorescent imaging of T2A-GAL4 gene trap and GFP or YFP fluorescent protein trap lines for 54 of the Drosophila genes and found 38 to be expressed in different cell types in Johnston's organ. We phenotypically characterized the function of strong loss-of-function mutants in three genes expressed in Johnston's organ (Cad99C, Msp-300, and Koi) using a courtship assay and electrophysiological recordings of sound-evoked potentials. Cad99C and Koi were found to have significant courtship defects. However, when we tested these genes for electrophysiological defects in hearing response, we did not see a significant difference suggesting the courtship defects were not caused by hearing deficiencies. Furthermore, we used a UAS/RNAi approach to test the function of seven genes and found two additional genes, CG5921 and Myo10a, that gave a statistically significant delay in courtship but not in sound-evoked potentials. Our results suggest that many mammalian deafness genes have Drosophila homologues expressed in the Johnston's organ, but that their requirement for hearing may not necessarily be the same as in mammals.
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Affiliation(s)
- Daniel C. Sutton
- Graduate Program in Genetics & Genomics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jonathan C. Andrews
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
| | - Dylan M. Dolezal
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Ye Jin Park
- Graduate Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, Texas, United States of America
- Huffington Center on Aging, One Baylor Plaza, Houston, Texas, United States of America
| | - Hongjie Li
- Graduate Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, Texas, United States of America
- Huffington Center on Aging, One Baylor Plaza, Houston, Texas, United States of America
| | - Daniel F. Eberl
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Shinya Yamamoto
- Graduate Program in Genetics & Genomics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, United States of America
- Graduate Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew K. Groves
- Graduate Program in Genetics & Genomics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Graduate Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
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4
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Zhang B, Duan H, Kavaler J, Wei L, Eberl DF, Lai EC. A nonneural miRNA cluster mediates hearing via repression of two neural targets. Genes Dev 2023; 37:1041-1051. [PMID: 38110249 PMCID: PMC10760640 DOI: 10.1101/gad.351052.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/29/2023] [Indexed: 12/20/2023]
Abstract
We show here that mir-279/996 are absolutely essential for development and function of Johnston's organ (JO), the primary proprioceptive and auditory organ in Drosophila Their deletion results in highly aberrant cell fate determination, including loss of scolopale cells and ectopic neurons, and mutants are electrophysiologically deaf. In vivo activity sensors and mosaic analyses indicate that these seed-related miRNAs function autonomously to suppress neural fate in nonneuronal cells. Finally, genetic interactions pinpoint two neural targets (elav and insensible) that underlie miRNA mutant JO phenotypes. This work uncovers how critical post-transcriptional regulation of specific miRNA targets governs cell specification and function of the auditory system.
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Affiliation(s)
- Binglong Zhang
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Hong Duan
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Joshua Kavaler
- Department of Biology, Colby College, Waterville, Maine 04901, USA
| | - Lu Wei
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Daniel F Eberl
- Department of Biology, University of Iowa, Iowa City, Iowa 52242, USA
| | - Eric C Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA;
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5
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Sharma Y, Jacobs JS, Sivan-Loukianova E, Lee E, Kernan MJ, Eberl DF. The retrograde IFT dynein is required for normal function of diverse mechanosensory cilia in Drosophila. Front Mol Neurosci 2023; 16:1263411. [PMID: 37808471 PMCID: PMC10556659 DOI: 10.3389/fnmol.2023.1263411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction Cilia biogenesis relies on intraflagellar transport (IFT), a conserved transport mechanism which functions bi-directionally to bring protein complexes to the growing ciliary tip and recycle signaling and transport proteins between the cilium and cell body. In Drosophila, anterograde IFT is critical for assembly of sensory cilia in the neurons of both chordotonal (ch) organs, which have relatively long ciliary axonemes, and external sensory (es) organs, which have short axonemal segments with microtubules in distal sensory segments forming non-axonemal bundles. We previously isolated the beethoven (btv) mutant in a mutagenesis screen for auditory mutants. Although many btv mutant flies are deaf, some retain a small residual auditory function as determined both by behavior and by auditory electrophysiology. Results Here we molecularly characterize the btv gene and demonstrate that it encodes the IFT-associated dynein-2 heavy chain Dync2h1. We also describe morphological changes in Johnston's organ as flies age to 30 days, and we find that morphological and electrophysiological phenotypes in this ch organ of btv mutants become more severe with age. We show that NompB protein, encoding the conserved IFT88 protein, an IFT complex B component, fails to be cleared from chordotonal cilia in btv mutants, instead accumulating in the distorted cilia. In macrochaete bristles, a class of es organ, btv mutants show a 50% reduction in mechanoreceptor potentials. Discussion Thus, the btv-encoded Dync2h1 functions as the retrograde IFT motor in the assembly of long ciliary axonemes in ch organs and is also important for normal function of the short ciliary axonemes in es organs.
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Affiliation(s)
- Yashoda Sharma
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Julie S. Jacobs
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | | | - Eugene Lee
- Department of Neurobiology and Behavior, State University of New York, Stony Brook, NY, United States
| | - Maurice J. Kernan
- Department of Neurobiology and Behavior, State University of New York, Stony Brook, NY, United States
| | - Daniel F. Eberl
- Department of Biology, The University of Iowa, Iowa City, IA, United States
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6
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Blagburn JM. A new method of recording from the giant fiber of Drosophila melanogaster shows that the strength of its auditory inputs remains constant with age. PLoS One 2020; 15:e0224057. [PMID: 31910219 PMCID: PMC6946141 DOI: 10.1371/journal.pone.0224057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/13/2019] [Indexed: 11/19/2022] Open
Abstract
There have been relatively few studies of how central synapses age in adult Drosophila melanogaster. In this study we investigate the aging of the synaptic inputs to the Giant Fiber (GF) from auditory Johnston's Organ neurons (JONs). In previously published experiments an indirect assay of this synaptic connection was used; here we describe a new, more direct assay, which allows reliable detection of the GF action potential in the neck connective, and long term recording of its responses to sound. Genetic poisoning using diphtheria toxin expressed in the GF with R68A06-GAL4 was used to confirm that this signal indeed arose from the GF and not from other descending neurons. As before, the sound-evoked action potentials (SEPs) in the antennal nerve were recorded via an electrode inserted at the base of the antenna. It was noted that an action potential in the GF elicited an antennal twitch, which in turn evoked a mechanosensory response from the JONs in the absence of sound. We then used these extracellular recording techniques in males and female of different ages to quantify the response of the JONs to a brief sound impulse, and also to measure the strength of the connection between the JONs and the GF. At no age was there any significant difference between males and females, for any of the parameters measured. The sensitivity of the JONs to a sound impulse approximately doubled between 1 d and 10 d after eclosion, which corresponds to the period when most mating is taking place. Subsequently JON sensitivity decreased with age, being approximately half as sensitive at 20 d and one-third as sensitive at 50 d, as compared to 10 d. However, the strength of the connection between the auditory input and the GF itself remained unchanged with age, although it did show some variability that could mask any small changes.
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Affiliation(s)
- Jonathan M. Blagburn
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, PR, United States of America
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7
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Li T, Giagtzoglou N, Eberl DF, Jaiswal SN, Cai T, Godt D, Groves AK, Bellen HJ. The E3 ligase Ubr3 regulates Usher syndrome and MYH9 disorder proteins in the auditory organs of Drosophila and mammals. eLife 2016; 5. [PMID: 27331610 PMCID: PMC4978524 DOI: 10.7554/elife.15258] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/21/2016] [Indexed: 01/08/2023] Open
Abstract
Myosins play essential roles in the development and function of auditory organs and multiple myosin genes are associated with hereditary forms of deafness. Using a forward genetic screen in Drosophila, we identified an E3 ligase, Ubr3, as an essential gene for auditory organ development. Ubr3 negatively regulates the mono-ubiquitination of non-muscle Myosin II, a protein associated with hearing loss in humans. The mono-ubiquitination of Myosin II promotes its physical interaction with Myosin VIIa, a protein responsible for Usher syndrome type IB. We show that ubr3 mutants phenocopy pathogenic variants of Myosin II and that Ubr3 interacts genetically and physically with three Usher syndrome proteins. The interactions between Myosin VIIa and Myosin IIa are conserved in the mammalian cochlea and in human retinal pigment epithelium cells. Our work reveals a novel mechanism that regulates protein complexes affected in two forms of syndromic deafness and suggests a molecular function for Myosin IIa in auditory organs.
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Affiliation(s)
- Tongchao Li
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Nikolaos Giagtzoglou
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Department of Neurology, Baylor College of Medicine, Houston, United States
| | - Daniel F Eberl
- Department of Biology, University of Iowa, Iowa City, United States
| | - Sonal Nagarkar Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Tiantian Cai
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Dorothea Godt
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Andrew K Groves
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
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8
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Pézier AP, Jezzini SH, Bacon JP, Blagburn JM. Shaking B Mediates Synaptic Coupling between Auditory Sensory Neurons and the Giant Fiber of Drosophila melanogaster. PLoS One 2016; 11:e0152211. [PMID: 27043822 PMCID: PMC4833477 DOI: 10.1371/journal.pone.0152211] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022] Open
Abstract
The Johnston’s Organ neurons (JONs) form chemical and electrical synapses onto the giant fiber neuron (GF), as part of the neuronal circuit that mediates the GF escape response in Drosophila melanogaster. The purpose of this study was to identify which of the 8 Drosophila innexins (invertebrate gap junction proteins) mediates the electrical connection at this synapse. The GF is known to express Shaking B (ShakB), specifically the ShakB(N+16) isoform only, at its output synapses in the thorax. The shakB2 mutation disrupts these GF outputs and also abolishes JON-GF synaptic transmission. However, the identity of the innexin that forms the presynaptic hemichannels in the JONs remains unknown. We used electrophysiology, immunocytochemistry and dye injection, along with presynaptically-driven RNA interference, to investigate this question. The amplitude of the compound action potential recorded in response to sound from the base of the antenna (sound-evoked potential, or SEP) was reduced by RNAi of the innexins Ogre, Inx3, Inx6 and, to a lesser extent Inx2, suggesting that they could be required in JONs for proper development, excitability, or synchronization of action potentials. The strength of the JON-GF connection itself was reduced to background levels only by RNAi of shakB, not of the other seven innexins. ShakB knockdown prevented Neurobiotin coupling between GF and JONs and removed the plaques of ShakB protein immunoreactivity that are present at the region of contact. Specific shakB RNAi lines that are predicted to target the ShakB(L) or ShakB(N) isoforms alone did not reduce the synaptic strength, implying that it is ShakB(N+16) that is required in the presynaptic neurons. Overexpression of ShakB(N+16) in JONs caused the formation of ectopic dye coupling, whereas ShakB(N) prevented it altogether, supporting this conclusion and also suggesting that gap junction proteins may have an instructive role in synaptic target choice.
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Affiliation(s)
- Adeline P. Pézier
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Sami H. Jezzini
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Jonathan P. Bacon
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Jonathan M. Blagburn
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
- * E-mail:
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9
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Chen JV, Kao LR, Jana SC, Sivan-Loukianova E, Mendonça S, Cabrera OA, Singh P, Cabernard C, Eberl DF, Bettencourt-Dias M, Megraw TL. Rootletin organizes the ciliary rootlet to achieve neuron sensory function in Drosophila. J Cell Biol 2015; 211:435-53. [PMID: 26483560 PMCID: PMC4621839 DOI: 10.1083/jcb.201502032] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 09/09/2015] [Indexed: 12/22/2022] Open
Abstract
Drosophila Rootletin organizes rootlets in sensory neurons, where it transmits multiple sensory inputs and maintains basal body cohesion, yet it is not required for cilium stability. Cilia are essential for cell signaling and sensory perception. In many cell types, a cytoskeletal structure called the ciliary rootlet links the cilium to the cell body. Previous studies indicated that rootlets support the long-term stability of some cilia. Here we report that Drosophila melanogaster Rootletin (Root), the sole orthologue of the mammalian paralogs Rootletin and C-Nap1, assembles into rootlets of diverse lengths among sensory neuron subtypes. Root mutant neurons lack rootlets and have dramatically impaired sensory function, resulting in behavior defects associated with mechanosensation and chemosensation. Root is required for cohesion of basal bodies, but the cilium structure appears normal in Root mutant neurons. We show, however, that normal rootlet assembly requires centrioles. The N terminus of Root contains a conserved domain and is essential for Root function in vivo. Ectopically expressed Root resides at the base of mother centrioles in spermatocytes and localizes asymmetrically to mother centrosomes in neuroblasts, both requiring Bld10, a basal body protein with varied functions.
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Affiliation(s)
- Jieyan V Chen
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Ling-Rong Kao
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Swadhin C Jana
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | | | | | - Oscar A Cabrera
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Priyanka Singh
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | | | - Daniel F Eberl
- Biology Department, University of Iowa, Iowa City, IA 52242
| | | | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
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10
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Boekhoff-Falk G, Eberl DF. The Drosophila auditory system. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2013; 3:179-91. [PMID: 24719289 DOI: 10.1002/wdev.128] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/28/2013] [Accepted: 09/10/2013] [Indexed: 11/10/2022]
Abstract
Development of a functional auditory system in Drosophila requires specification and differentiation of the chordotonal sensilla of Johnston's organ (JO) in the antenna, correct axonal targeting to the antennal mechanosensory and motor center in the brain, and synaptic connections to neurons in the downstream circuit. Chordotonal development in JO is functionally complicated by structural, molecular, and functional diversity that is not yet fully understood, and construction of the auditory neural circuitry is only beginning to unfold. Here, we describe our current understanding of developmental and molecular mechanisms that generate the exquisite functions of the Drosophila auditory system, emphasizing recent progress and highlighting important new questions arising from research on this remarkable sensory system.
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Affiliation(s)
- Grace Boekhoff-Falk
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
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11
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Pézier A, Blagburn JM. Auditory responses of engrailed and invected-expressing Johnston's Organ neurons in Drosophila melanogaster. PLoS One 2013; 8:e71419. [PMID: 23940751 PMCID: PMC3734059 DOI: 10.1371/journal.pone.0071419] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 07/03/2013] [Indexed: 11/23/2022] Open
Abstract
The roles of the transcription factor Engrailed (En), and its paralogue Invected (Inv), in adult Drosophila Johnston’s Organ sensory neurons are unknown. We used en-GAL4 driven CD8-GFP and antibody staining to characterize these neurons in the pedicel (second antennal segment). The majority of En and Inv-expressing Johnston’s Organ neurons (En-JONs) are located in the ventral part of the posterior group of JONs, with only a few in the medial group. Anatomical classification of En-JON axon projections shows they are mainly type A and E, with a few type B. Extracellular recording of sound-evoked potentials (SEPs) from the antennal nerve was used along with Kir2.1 silencing to assess the contribution that En-JONs make to the auditory response to pure-tone sound stimuli. Silencing En-JONs reduces the SEP amplitude at the onset of the stimulus by about half at 100, 200 and 400 Hz, and also reduces the steady-state response to 200 Hz. En-JONs respond to 82 dB and 92 dB sounds but not 98 dB. Despite their asymmetrical distribution in the Johnston’s Organ they respond equally strongly to both directions of movement of the arista. This implies that individual neurons are excited in both directions, a conclusion supported by reanalysis of the morphology of the pedicel-funicular joint. Other methods of silencing the JONs were also used: RNAi against the voltage-gated Na+ channel encoded by the para gene, expression of attenuated diphtheria toxin, and expression of a modified influenza toxin M2(H37A). Only the latter was found to be more effective than Kir2.1. Three additional JON subsets were characterized using Flylight GAL4 lines. inv-GAL4 88B12 and Gycβ100B-GAL4 12G03 express in different subsets of A group neurons and CG12484-GAL4 91G04 is expressed in B neurons. All three contribute to the auditory response to 200 Hz tones.
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Affiliation(s)
- Adeline Pézier
- Institute of Neurobiology, University of Puerto Rico, San Juan, Puerto Rico, United States of America
| | - Jonathan M. Blagburn
- Institute of Neurobiology, University of Puerto Rico, San Juan, Puerto Rico, United States of America
- * E-mail:
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12
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Bharadwaj R, Roy M, Ohyama T, Sivan-Loukianova E, Delannoy M, Lloyd TE, Zlatic M, Eberl DF, Kolodkin AL. Cbl-associated protein regulates assembly and function of two tension-sensing structures in Drosophila. Development 2013; 140:627-38. [PMID: 23293294 DOI: 10.1242/dev.085100] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cbl-associated protein (CAP) localizes to focal adhesions and associates with numerous cytoskeletal proteins; however, its physiological roles remain unknown. Here, we demonstrate that Drosophila CAP regulates the organization of two actin-rich structures in Drosophila: muscle attachment sites (MASs), which connect somatic muscles to the body wall; and scolopale cells, which form an integral component of the fly chordotonal organs and mediate mechanosensation. Drosophila CAP mutants exhibit aberrant junctional invaginations and perturbation of the cytoskeletal organization at the MAS. CAP depletion also results in collapse of scolopale cells within chordotonal organs, leading to deficits in larval vibration sensation and adult hearing. We investigate the roles of different CAP protein domains in its recruitment to, and function at, various muscle subcellular compartments. Depletion of the CAP-interacting protein Vinculin results in a marked reduction in CAP levels at MASs, and vinculin mutants partially phenocopy Drosophila CAP mutants. These results show that CAP regulates junctional membrane and cytoskeletal organization at the membrane-cytoskeletal interface of stretch-sensitive structures, and they implicate integrin signaling through a CAP/Vinculin protein complex in stretch-sensitive organ assembly and function.
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Affiliation(s)
- Rajnish Bharadwaj
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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Lehnert BP, Baker AE, Gaudry Q, Chiang AS, Wilson RI. Distinct roles of TRP channels in auditory transduction and amplification in Drosophila. Neuron 2013; 77:115-28. [PMID: 23312520 PMCID: PMC3811118 DOI: 10.1016/j.neuron.2012.11.030] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2012] [Indexed: 11/26/2022]
Abstract
Auditory receptor cells rely on mechanically gated channels to transform sound stimuli into neural activity. Several TRP channels have been implicated in Drosophila auditory transduction, but mechanistic studies have been hampered by the inability to record subthreshold signals from receptor neurons. Here, we develop a non-invasive method for measuring these signals by recording from a central neuron that is electrically coupled to a genetically defined population of auditory receptor cells. We find that the TRPN family member NompC, which is necessary for the active amplification of sound-evoked motion by the auditory organ, is not required for transduction in auditory receptor cells. Instead, NompC sensitizes the transduction complex to movement and precisely regulates the static forces on the complex. In contrast, the TRPV channels Nanchung and Inactive are required for responses to sound, suggesting they are components of the transduction complex. Thus, transduction and active amplification are genetically separable processes in Drosophila hearing.
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Affiliation(s)
- Brendan P Lehnert
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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Cell-type-specific roles of Na+/K+ ATPase subunits in Drosophila auditory mechanosensation. Proc Natl Acad Sci U S A 2012; 110:181-6. [PMID: 23248276 DOI: 10.1073/pnas.1208866110] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Ion homeostasis is a fundamental cellular process particularly important in excitable cell activities such as hearing. It relies on the Na(+)/K(+) ATPase (also referred to as the Na pump), which is composed of a catalytic α subunit and a β subunit required for its transport to the plasma membrane and for regulating its activity. We show that α and β subunits are expressed in Johnston's organ (JO), the Drosophila auditory organ. We knocked down expression of α subunits (ATPα and α-like) and β subunits (nrv1, nrv2, and nrv3) individually in JO with UAS/Gal4-mediated RNAi. ATPα shows elevated expression in the ablumenal membrane of scolopale cells, which enwrap JO neuronal dendrites in endolymph-like compartments. Knocking down ATPα, but not α-like, in the entire JO or only in scolopale cells using specific drivers, resulted in complete deafness. Among β subunits, nrv2 is expressed in scolopale cells and nrv3 in JO neurons. Knocking down nrv2 in scolopale cells blocked Nrv2 expression, reduced ATPα expression in the scolopale cells, and caused almost complete deafness. Furthermore, knockdown of either nrv2 or ATPα specifically in scolopale cells causes abnormal, electron-dense material accumulation in the scolopale space. Similarly, nrv3 functions in JO but not in scolopale cells, suggesting neuron specificity that parallels nrv2 scolopale cell-specific support of the catalytic ATPα. Our studies provide an amenable model to investigate generation of endolymph-like extracellular compartments.
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Enjolras C, Thomas J, Chhin B, Cortier E, Duteyrat JL, Soulavie F, Kernan MJ, Laurençon A, Durand B. Drosophila chibby is required for basal body formation and ciliogenesis but not for Wg signaling. ACTA ACUST UNITED AC 2012; 197:313-25. [PMID: 22508513 PMCID: PMC3328381 DOI: 10.1083/jcb.201109148] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In contrast to vertebrate CBY, which functions in WNT signaling, Drosophila CBY is essential for normal basal body structure and function but dispensable for Wg signaling. Centriole-to–basal body conversion, a complex process essential for ciliogenesis, involves the progressive addition of specific proteins to centrioles. CHIBBY (CBY) is a coiled-coil domain protein first described as interacting with β-catenin and involved in Wg-Int (WNT) signaling. We found that, in Drosophila melanogaster, CBY was exclusively expressed in cells that require functional basal bodies, i.e., sensory neurons and male germ cells. CBY was associated with the basal body transition zone (TZ) in these two cell types. Inactivation of cby led to defects in sensory transduction and in spermatogenesis. Loss of CBY resulted in altered ciliary trafficking into neuronal cilia, irregular deposition of proteins on spermatocyte basal bodies, and, consequently, distorted axonemal assembly. Importantly, cby1/1 flies did not show Wingless signaling defects. Hence, CBY is essential for normal basal body structure and function in Drosophila, potentially through effects on the TZ. The function of CBY in WNT signaling in vertebrates has either been acquired during vertebrate evolution or lost in Drosophila.
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Affiliation(s)
- Camille Enjolras
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR 5534, Université Claude Bernard Lyon 1, Villeurbanne, Lyon F69622, France
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