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Zhang Q, Zhang P, Yang M, Tian Y, Feng C, Wei W. Identifications of three novel alleles of Serrate in Drosophila. Cells Dev 2024; 177:203908. [PMID: 38403117 DOI: 10.1016/j.cdev.2024.203908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 02/18/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
The Notch signaling pathway, an evolutionarily highly conserved pathway, participates in various essential physiological processes in organisms. Activation of Notch signaling in the canonical manner requires the combination of ligand and receptor. There are two ligands of Notch in Drosophila: Delta (Dl) and Serrate (Ser). A mutation mf157 is identified for causing nicks of fly wings in genetic analysis from a mutant library (unpublished) that was established previously. Immunofluorescent staining illustrates that mf157 represses the expression of Cut and Wingless (Wg), the targets of Notch signaling. MARCM cloning analysis reveals that mf157 functions at the same level or the upstream of ligands of Notch in signaling sending cells. Sequencing demonstrates that mf157 is a novel allele of the Ser gene. Subsequently, mf553 and mf167 are also identified as new alleles of Ser from our library. Furthermore, the complementary assays and the examination of transcripts confirm the sequencing results. Besides, the repressed phenotypes of Notch signaling were reverted by transposon excision experiments of mf157. In conclusion, we identify three fresh alleles of Ser. Our works supply additional genetic resources for further study of functions of Ser and Notch signaling regulation.
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Affiliation(s)
- Qinghai Zhang
- Key Laboratory of Medical Insects, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China; Department of Biology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China; Research Center for Basic Sciences of Medicine, Guizhou Medical University, Guiyang 550025, China.
| | - Pei Zhang
- Key Laboratory of Medical Insects, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China; Department of Biology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China
| | - Min Yang
- Department of Biology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China
| | - Yingxue Tian
- Department of Biology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China
| | - Chunxia Feng
- Department of Biology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China
| | - Wei Wei
- Multimedia Laboratory of Morphology, College of Basic Medicine, Guizhou Medical University, Guiyang 550025, China.
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2
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Abidi SNF, Hsu FTY, Smith-Bolton RK. Regenerative growth is constrained by brain tumor to ensure proper patterning in Drosophila. PLoS Genet 2023; 19:e1011103. [PMID: 38127821 PMCID: PMC10769103 DOI: 10.1371/journal.pgen.1011103] [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: 05/03/2023] [Revised: 01/05/2024] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
Some animals respond to injury by inducing new growth to regenerate the lost structures. This regenerative growth must be carefully controlled and constrained to prevent aberrant growth and to allow correct organization of the regenerating tissue. However, the factors that restrict regenerative growth have not been identified. Using a genetic ablation system in the Drosophila wing imaginal disc, we have identified one mechanism that constrains regenerative growth, impairment of which also leads to erroneous patterning of the final appendage. Regenerating discs with reduced levels of the RNA-regulator Brain tumor (Brat) exhibit enhanced regeneration, but produce adult wings with disrupted margins that are missing extensive tracts of sensory bristles. In these mutants, aberrantly high expression of the pro-growth factor Myc and its downstream targets likely contributes to this loss of cell-fate specification. Thus, Brat constrains the expression of pro-regeneration genes and ensures that the regenerating tissue forms the proper final structure.
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Affiliation(s)
- Syeda Nayab Fatima Abidi
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Felicity Ting-Yu Hsu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Rachel K. Smith-Bolton
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Carle R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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3
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Lim Y. Transcription factors in microcephaly. Front Neurosci 2023; 17:1302033. [PMID: 38094004 PMCID: PMC10716367 DOI: 10.3389/fnins.2023.1302033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/06/2023] [Indexed: 02/01/2024] Open
Abstract
Higher cognition in humans, compared to other primates, is often attributed to an increased brain size, especially forebrain cortical surface area. Brain size is determined through highly orchestrated developmental processes, including neural stem cell proliferation, differentiation, migration, lamination, arborization, and apoptosis. Disruption in these processes often results in either a small (microcephaly) or large (megalencephaly) brain. One of the key mechanisms controlling these developmental processes is the spatial and temporal transcriptional regulation of critical genes. In humans, microcephaly is defined as a condition with a significantly smaller head circumference compared to the average head size of a given age and sex group. A growing number of genes are identified as associated with microcephaly, and among them are those involved in transcriptional regulation. In this review, a subset of genes encoding transcription factors (e.g., homeobox-, basic helix-loop-helix-, forkhead box-, high mobility group box-, and zinc finger domain-containing transcription factors), whose functions are important for cortical development and implicated in microcephaly, are discussed.
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Affiliation(s)
- Youngshin Lim
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Biomedical Science Education, Charles R. Drew University of Medicine and Science, Los Angeles, CA, United States
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4
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Nakano H, Sakai T. Impact of Drosophila LIM homeodomain protein Apterous on the morphology of the adult mushroom body. Biochem Biophys Res Commun 2023; 682:77-84. [PMID: 37804590 DOI: 10.1016/j.bbrc.2023.09.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 09/23/2023] [Indexed: 10/09/2023]
Abstract
A LIM homeodomain transcription factor Apterous (Ap) regulates embryonic and larval neurodevelopment in Drosophila. Although Ap is still expressed in the adult brain, it remains elusive whether Ap is involved in neurodevelopmental events in the adult brain because flies homozygous for ap mutations are usually lethal before they reach the adult stage. In this study, using adult escapers of ap knockout (KO) homozygotes, we examined whether the complete lack of ap expression affects the morphology of the mushroom body (MB) neurons and Pigment-dispersing factor (Pdf)-positive clock neurons in the adult brain. Although ap KO escapers showed severe structural defects of MB neurons, no clear morphological defects were found in Pdf-positive clock neurons. These results suggest that Ap in the adult brain is essential for the neurodevelopment of specific ap-positive neurons, but it is not necessarily involved in the development of all ap-positive neurons.
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Affiliation(s)
- Hikari Nakano
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Takaomi Sakai
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, 192-0397, Japan.
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5
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Thayer RC, Patel NH. A meta-analysis of butterfly structural colors: their color range, distribution and biological production. J Exp Biol 2023; 226:jeb245940. [PMID: 37937662 DOI: 10.1242/jeb.245940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Butterfly scales are among the richest natural sources of optical nanostructures, which produce structural color and iridescence. Several recurring nanostructure types have been described, such as ridge multilayers, gyroids and lower lamina thin films. While the optical mechanisms of these nanostructure classes are known, their phylogenetic distributions and functional ranges have not been described in detail. In this Review, we examine a century of research on the biological production of structural colors, including their evolution, development and genetic regulation. We have also created a database of more than 300 optical nanostructures in butterflies and conducted a meta-analysis of the color range, abundance and phylogenetic distribution of each nanostructure class. Butterfly structural colors are ubiquitous in short wavelengths but extremely rare in long wavelengths, especially red. In particular, blue wavelengths (around 450 nm) occur in more clades and are produced by more kinds of nanostructures than other hues. Nanostructure categories differ in prevalence, phylogenetic distribution, color range and brightness. For example, lamina thin films are the least bright; perforated lumen multilayers occur most often but are almost entirely restricted to the family Lycaenidae; and 3D photonic crystals, including gyroids, have the narrowest wavelength range (from about 450 to 550 nm). We discuss the implications of these patterns in terms of nanostructure evolution, physical constraint and relationships to pigmentary color. Finally, we highlight opportunities for future research, such as analyses of subadult and Hesperid structural colors and the identification of genes that directly build the nanostructures, with relevance for biomimetic engineering.
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Affiliation(s)
- Rachel C Thayer
- Department of Evolution and Ecology, University of California, Davis, Davis, CA 95616, USA
| | - Nipam H Patel
- Marine Biological Laboratory, Woods Hole, MA 02543, USA
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Singh J, Karunaraj P, Luf M, Pfleger CM. Lysines K117 and K147 play conserved roles in Ras activation from Drosophila to mammals. G3 (BETHESDA, MD.) 2023; 13:jkad201. [PMID: 37665961 PMCID: PMC10627255 DOI: 10.1093/g3journal/jkad201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023]
Abstract
Ras signaling plays an important role in growth, proliferation, and developmental patterning. Maintaining appropriate levels of Ras signaling is important to establish patterning in development and to prevent diseases such as cancer in mature organisms. The Ras protein is represented by Ras85D in Drosophila and by HRas, NRas, and KRas in mammals. In the past dozen years, multiple reports have characterized both inhibitory and activating ubiquitination events regulating Ras proteins. Inhibitory Ras ubiquitination mediated by Rabex-5 or Lztr1 is highly conserved between flies and mammals. Activating ubiquitination events at K117 and K147 have been reported in mammalian HRas, NRas, and KRas, but it is unclear if these activating roles of K117 and K147 are conserved in flies. Addressing a potential conserved role for these lysines in Drosophila Ras activation requires phenotypes strong enough to assess suppression. Therefore, we utilized oncogenic Ras, RasG12V, which biases Ras to the GTP-loaded active conformation. We created double mutants RasG12V,K117R and RasG12V,K147R and triple mutant RasG12V,K117R,K147R to prevent lysine-specific post-translational modification of K117, K147, or both, respectively. We compared their phenotypes to RasG12V in the wing to reveal the roles of these lysines. Although RasG12V,K147R did not show compelling or quantifiable differences from RasG12V, RasG12V,K117R showed visible and quantifiable suppression compared to RasG12V, and triple mutant RasG12V,K117R,K147R showed dramatic suppression compared to RasG12V and increased suppression compared to RasG12V,K117R. These data are consistent with highly conserved roles for K117 and K147 in Ras activation from flies to mammals.
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Affiliation(s)
- Jiya Singh
- Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Tisch Cancer Institute, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Prashath Karunaraj
- Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Tisch Cancer Institute, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Max Luf
- Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Tisch Cancer Institute, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Cathie M Pfleger
- Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Tisch Cancer Institute, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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7
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Liu XZ, Guo H, Long GJ, Ma YF, Gong LL, Zhang MQ, Hull JJ, Dewer Y, Liu LW, He M, He P. Functional characterization of five developmental signaling network genes in the white-backed planthopper: Potential application for pest management. PEST MANAGEMENT SCIENCE 2023. [PMID: 36942746 DOI: 10.1002/ps.7464] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 02/14/2023] [Accepted: 03/19/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND The white-backed planthopper (WBPH, Sogatella furcifera) is a major rice pest that exhibits condition dependent wing dimorphisms - a macropterous (long wing) form and a brachypterous (short wing) form. Although, the gene cascade that regulates wing development and dimorphic differentiation has been largely defined, the utility of these genes as targets for pest control has yet to be fully explored. RESULTS Five genes typically associated with the developmental signaling network, armadillo (arm), apterous A (apA), scalloped (sd), dachs (d), and yorkie (yki) were identified from the WBPH genome and their roles in wing development assessed following RNA interference (RNAi)-mediated knockdown. At 5 days-post injection, transcript levels for all five targets were substantially decreased compared with the dsGFP control group. Among the treatment groups, those injected with dsSfarm had the most pronounced effects on transcript reduction, mortality (95 ± 3%), and incidence (45 ± 3%) of wing deformities, whereas those injected with dsSfyki had the lowest incidence (6.7 ± 4%). To assess the utility of topical RNAi for Sfarm, we used a spray-based approach that complexed a large-scale, bacteria-based double-stranded RNA (dsRNA) expression pipeline with star polycation (SPc) nanoparticles. Rice seedlings infested with third and fourth instar nymphs were sprayed with SPc-dsRNA formulations and RNAi phenotypic effects were assessed over time. At 2 days post-spray, Sfarm transcript levels decreased by 86 ± 9.5% compared with dsGFP groups, and the subsequent incidences of mortality and wing defects were elevated in the treatment group. CONCLUSIONS This study characterized five genes in the WBPH developmental signaling cascade, assessed their impact on survival and wing development via RNAi, and developed a nanoparticle-dsRNA spray approach for potential field control of WBPH. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Xuan-Zheng Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Huan Guo
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Gui-Jun Long
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Yun-Feng Ma
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Lang-Lang Gong
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Meng-Qi Zhang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - J Joe Hull
- Pest Management and Biocontrol Research Unit, US Arid Land Agricultural Research Center, USDA Agricultural Research Services, Maricopa, Arizona, USA
| | - Youssef Dewer
- Phytotoxicity Research Department, Central Agricultural Pesticide Laboratory, Agricultural Research Center, Dokki, Giza, Egypt
| | - Li-Wei Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Ming He
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
| | - Peng He
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyan, People's Republic of China
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8
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Chen M, Gao E, Lin G, Shen J, Wang D. The transcription factor optomotor-blind restricts apterous expression through TrxG and PcG genes. Dev Biol 2023; 497:59-67. [PMID: 36907311 DOI: 10.1016/j.ydbio.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/20/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023]
Abstract
The establishment of body pattern is a fundamental process in developmental biology. In Drosophila, the wing disc is subdivided into dorsal (D) and ventral (V) compartments by the D/V boundary. The dorsal fate is adopted by expressing the selector gene apterous (ap). ap expression is regulated by three combinational cis-regulatory modules which are activated by EGFR pathway, Ap-Vg auto-regulatory and epigenetic mechanisms. Here, we found that the Tbx family transcription factor Optomotor-blind (Omb) restricted ap expression in the ventral compartment. Loss of omb induced autonomous initiation of ap expression in the middle third instar larvae in the ventral compartment. Oppositely, over-activation of omb inhibited ap in the medial pouch. All three enhancers apE, apDV and apP were upregulated in omb null mutants, indicating a combinational regulation of ap modulators. However, Omb affected ap expression neither by directly regulating EGFR signaling, nor via Vg regulation. Therefore, a genetic screen of epigenetic regulators, including the Trithorax group (TrxG) and Polycomb group (PcG) genes was performed. We found that knocking down the TrxG gene kohtalo (kto), domino (dom) or expressing the PcG gene grainy head (grh), the ectopic ap in omb mutants was repressed. The inhibition of apDV by kto knockdown and grh activation could contribute to ap repression. Moreover, Omb and the EGFR pathway are genetically parallel in ap regulation in the ventral compartment. Collectively, Omb is a repressive signal for ap expression in the ventral compartment, which requires TrxG and PcG genes.
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Affiliation(s)
- Min Chen
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, 100193, China; Yantai Academy of Agricultural Sciences, Yantai, 265500, China
| | - Erqing Gao
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Guangze Lin
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Jie Shen
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Dan Wang
- Department of Plant Biosecurity and MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, 100193, China.
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Zhang Y, Lowe S, Ding AZ, Li X. Notch-dependent binary fate choice regulates the Netrin pathway to control axon guidance of Drosophila visual projection neurons. Cell Rep 2023; 42:112143. [PMID: 36821442 PMCID: PMC10124989 DOI: 10.1016/j.celrep.2023.112143] [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: 01/13/2022] [Revised: 10/22/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
Notch-dependent binary fate choice between sister neurons is one of the mechanisms to generate neural diversity. How these upstream neural fate specification programs regulate downstream effector genes to control axon targeting and neuropil assembly remains less well understood. Here, we report that Notch-dependent binary fate choice in Drosophila medulla neurons is required to regulate the Netrin axon guidance pathway, which controls targeting of transmedullary (Tm) neurons to lobula. In medulla neurons of Notch-on hemilineage composed of mostly lobula-targeting neurons, Notch signaling is required to activate the expression of Netrin-B and repress the expression of its repulsive receptor Unc-5. Turning off Unc-5 is necessary for Tm neurons to target lobula. Furthermore, Netrin-B provided by Notch-on medulla neurons is required for correct targeting of Tm axons from later-generated medulla columns. Thus, the coordinate regulation of Netrin pathway components by Notch signaling ensures correct targeting of Tm axons and contributes to the neuropil assembly.
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Affiliation(s)
- Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Scott Lowe
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Andrew Z Ding
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
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Diacou R, Nandigrami P, Fiser A, Liu W, Ashery-Padan R, Cvekl A. Cell fate decisions, transcription factors and signaling during early retinal development. Prog Retin Eye Res 2022; 91:101093. [PMID: 35817658 PMCID: PMC9669153 DOI: 10.1016/j.preteyeres.2022.101093] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/30/2022]
Abstract
The development of the vertebrate eyes is a complex process starting from anterior-posterior and dorso-ventral patterning of the anterior neural tube, resulting in the formation of the eye field. Symmetrical separation of the eye field at the anterior neural plate is followed by two symmetrical evaginations to generate a pair of optic vesicles. Next, reciprocal invagination of the optic vesicles with surface ectoderm-derived lens placodes generates double-layered optic cups. The inner and outer layers of the optic cups develop into the neural retina and retinal pigment epithelium (RPE), respectively. In vitro produced retinal tissues, called retinal organoids, are formed from human pluripotent stem cells, mimicking major steps of retinal differentiation in vivo. This review article summarizes recent progress in our understanding of early eye development, focusing on the formation the eye field, optic vesicles, and early optic cups. Recent single-cell transcriptomic studies are integrated with classical in vivo genetic and functional studies to uncover a range of cellular mechanisms underlying early eye development. The functions of signal transduction pathways and lineage-specific DNA-binding transcription factors are dissected to explain cell-specific regulatory mechanisms underlying cell fate determination during early eye development. The functions of homeodomain (HD) transcription factors Otx2, Pax6, Lhx2, Six3 and Six6, which are required for early eye development, are discussed in detail. Comprehensive understanding of the mechanisms of early eye development provides insight into the molecular and cellular basis of developmental ocular anomalies, such as optic cup coloboma. Lastly, modeling human development and inherited retinal diseases using stem cell-derived retinal organoids generates opportunities to discover novel therapies for retinal diseases.
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Affiliation(s)
- Raven Diacou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Prithviraj Nandigrami
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andras Fiser
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Wei Liu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ruth Ashery-Padan
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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11
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Zhu H, Zhao SD, Ray A, Zhang Y, Li X. A comprehensive temporal patterning gene network in Drosophila medulla neuroblasts revealed by single-cell RNA sequencing. Nat Commun 2022; 13:1247. [PMID: 35273186 PMCID: PMC8913700 DOI: 10.1038/s41467-022-28915-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 02/12/2022] [Indexed: 12/24/2022] Open
Abstract
During development, neural progenitors are temporally patterned to sequentially generate a variety of neural types. In Drosophila neural progenitors called neuroblasts, temporal patterning is regulated by cascades of Temporal Transcription Factors (TTFs). However, known TTFs were mostly identified through candidate approaches and may not be complete. In addition, many fundamental questions remain concerning the TTF cascade initiation, progression, and termination. In this work, we use single-cell RNA sequencing of Drosophila medulla neuroblasts of all ages to identify a list of previously unknown TTFs, and experimentally characterize their roles in temporal patterning and neuronal specification. Our study reveals a comprehensive temporal gene network that patterns medulla neuroblasts from start to end. Furthermore, the speed of the cascade progression is regulated by Lola transcription factors expressed in all medulla neuroblasts. Our comprehensive study of the medulla neuroblast temporal cascade illustrates mechanisms that may be conserved in the temporal patterning of neural progenitors. During development, neural progenitors generate a variety of neural types sequentially. Here the authors examine gene expression patterns in Drosophila neural progenitors at single-cell level, and identify a gene regulatory network controlling the sequential generation of different neural types.
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Affiliation(s)
- Hailun Zhu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sihai Dave Zhao
- Department of Statistics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Alokananda Ray
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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12
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García-García M, Sánchez-Perales S, Jarabo P, Calvo E, Huyton T, Fu L, Ng SC, Sotodosos-Alonso L, Vázquez J, Casas-Tintó S, Görlich D, Echarri A, Del Pozo MA. Mechanical control of nuclear import by Importin-7 is regulated by its dominant cargo YAP. Nat Commun 2022; 13:1174. [PMID: 35246520 PMCID: PMC8897400 DOI: 10.1038/s41467-022-28693-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 01/19/2022] [Indexed: 12/31/2022] Open
Abstract
Mechanical forces regulate multiple essential pathways in the cell. The nuclear translocation of mechanoresponsive transcriptional regulators is an essential step for mechanotransduction. However, how mechanical forces regulate the nuclear import process is not understood. Here, we identify a highly mechanoresponsive nuclear transport receptor (NTR), Importin-7 (Imp7), that drives the nuclear import of YAP, a key regulator of mechanotransduction pathways. Unexpectedly, YAP governs the mechanoresponse of Imp7 by forming a YAP/Imp7 complex that responds to mechanical cues through the Hippo kinases MST1/2. Furthermore, YAP behaves as a dominant cargo of Imp7, restricting the Imp7 binding and the nuclear translocation of other Imp7 cargoes such as Smad3 and Erk2. Thus, the nuclear import process is an additional regulatory layer indirectly regulated by mechanical cues, which activate a preferential Imp7 cargo, YAP, which competes out other cargoes, resulting in signaling crosstalk. The translation of mechanical cues into gene expression changes is dependent on the nuclear import of mechanoresponsive transcriptional regulators. Here the authors identify that Importin-7 drives the nuclear import of one such regulator YAP while YAP then controls Importin-7 response to mechanical cues and restricts Importin-7 binding to other cargoes.
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Affiliation(s)
- María García-García
- Mechanoadaptation and Caveolae Biology Laboratory. Area of Cell & Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain
| | - Sara Sánchez-Perales
- Mechanoadaptation and Caveolae Biology Laboratory. Area of Cell & Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain
| | - Patricia Jarabo
- Instituto Cajal-CSIC, Avda. Doctor Arce, 37, 28002, Madrid, Spain
| | - Enrique Calvo
- Proteomics Unit. Area of Vascular Physiopathology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain.,CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Trevor Huyton
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Liran Fu
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Sheung Chun Ng
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Laura Sotodosos-Alonso
- Mechanoadaptation and Caveolae Biology Laboratory. Area of Cell & Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain
| | - Jesús Vázquez
- Proteomics Unit. Area of Vascular Physiopathology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain.,CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | | | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Asier Echarri
- Mechanoadaptation and Caveolae Biology Laboratory. Area of Cell & Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain.
| | - Miguel A Del Pozo
- Mechanoadaptation and Caveolae Biology Laboratory. Area of Cell & Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle Melchor Fernández Almagro, 3, 28029, Madrid, Spain.
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13
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Abstract
The Drosophila wing imaginal disc is a tissue of undifferentiated cells that are precursors of the wing and most of the notum of the adult fly. The wing disc first forms during embryogenesis from a cluster of ∼30 cells located in the second thoracic segment, which invaginate to form a sac-like structure. They undergo extensive proliferation during larval stages to form a mature larval wing disc of ∼35,000 cells. During this time, distinct cell fates are assigned to different regions, and the wing disc develops a complex morphology. Finally, during pupal stages the wing disc undergoes morphogenetic processes and then differentiates to form the adult wing and notum. While the bulk of the wing disc comprises epithelial cells, it also includes neurons and glia, and is associated with tracheal cells and muscle precursor cells. The relative simplicity and accessibility of the wing disc, combined with the wealth of genetic tools available in Drosophila, have combined to make it a premier system for identifying genes and deciphering systems that play crucial roles in animal development. Studies in wing imaginal discs have made key contributions to many areas of biology, including tissue patterning, signal transduction, growth control, regeneration, planar cell polarity, morphogenesis, and tissue mechanics.
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Affiliation(s)
- Bipin Kumar Tripathi
- Department of Molecular Biology and Biochemistry, Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA
| | - Kenneth D Irvine
- Department of Molecular Biology and Biochemistry, Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA
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14
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Fisher CR, Kratovil JD, Angelini DR, Jockusch EL. Out from under the wing: reconceptualizing the insect wing gene regulatory network as a versatile, general module for body-wall lobes in arthropods. Proc Biol Sci 2021; 288:20211808. [PMID: 34933597 PMCID: PMC8692954 DOI: 10.1098/rspb.2021.1808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/29/2021] [Indexed: 12/24/2022] Open
Abstract
Body plan evolution often occurs through the differentiation of serially homologous body parts, particularly in the evolution of arthropod body plans. Recently, homeotic transformations resulting from experimental manipulation of gene expression, along with comparative data on the expression and function of genes in the wing regulatory network, have provided a new perspective on an old question in insect evolution: how did the insect wing evolve? We investigated the metamorphic roles of a suite of 10 wing- and body-wall-related genes in a hemimetabolous insect, Oncopeltus fasciatus. Our results indicate that genes involved in wing development in O. fasciatus play similar roles in the development of adult body-wall flattened cuticular evaginations. We found extensive functional similarity between the development of wings and other bilayered evaginations of the body wall. Overall, our results support the existence of a versatile development module for building bilayered cuticular epithelial structures that pre-dates the evolutionary origin of wings. We explore the consequences of reconceptualizing the canonical wing-patterning network as a bilayered body-wall patterning network, including consequences for long-standing debates about wing homology, the origin of wings and the origin of novel bilayered body-wall structures. We conclude by presenting three testable predictions that result from this reconceptualization.
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Affiliation(s)
- Cera R. Fisher
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Justin D. Kratovil
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | | | - Elizabeth L. Jockusch
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
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15
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Consolidation and maintenance of long-term memory involve dual functions of the developmental regulator Apterous in clock neurons and mushroom bodies in the Drosophila brain. PLoS Biol 2021; 19:e3001459. [PMID: 34860826 PMCID: PMC8641882 DOI: 10.1371/journal.pbio.3001459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 10/25/2021] [Indexed: 11/23/2022] Open
Abstract
Memory is initially labile but can be consolidated into stable long-term memory (LTM) that is stored in the brain for extended periods. Despite recent progress, the molecular and cellular mechanisms underlying the intriguing neurobiological processes of LTM remain incompletely understood. Using the Drosophila courtship conditioning assay as a memory paradigm, here, we show that the LIM homeodomain (LIM-HD) transcription factor Apterous (Ap), which is known to regulate various developmental events, is required for both the consolidation and maintenance of LTM. Interestingly, Ap is involved in these 2 memory processes through distinct mechanisms in different neuronal subsets in the adult brain. Ap and its cofactor Chip (Chi) are indispensable for LTM maintenance in the Drosophila memory center, the mushroom bodies (MBs). On the other hand, Ap plays a crucial role in memory consolidation in a Chi-independent manner in pigment dispersing factor (Pdf)-containing large ventral–lateral clock neurons (l-LNvs) that modulate behavioral arousal and sleep. Since disrupted neurotransmission and electrical silencing in clock neurons impair memory consolidation, Ap is suggested to contribute to the stabilization of memory by ensuring the excitability of l-LNvs. Indeed, ex vivo imaging revealed that a reduced function of Ap, but not Chi, results in exaggerated Cl− responses to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in l-LNvs, indicating that wild-type (WT) Ap maintains high l-LNv excitability by suppressing the GABA response. Consistently, enhancing the excitability of l-LNvs by knocking down GABAA receptors compensates for the impaired memory consolidation in ap null mutants. Overall, our results revealed unique dual functions of the developmental regulator Ap for LTM consolidation in clock neurons and LTM maintenance in MBs. A neurogenetic study using Drosophila reveals that the centrally expressed LIM-homeodomain transcription factor Apterous plays a crucial neuron-type-dependent role in two different memory processes - consolidation and maintenance of long-term memory.
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16
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Soares MPM, Pinheiro DG, de Paula Freitas FC, Simões ZLP, Bitondi MMG. Transcriptome dynamics during metamorphosis of imaginal discs into wings and thoracic dorsum in Apis mellifera castes. BMC Genomics 2021; 22:756. [PMID: 34674639 PMCID: PMC8532292 DOI: 10.1186/s12864-021-08040-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 09/20/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Much of the complex anatomy of a holometabolous insect is built from disc-shaped epithelial structures found inside the larva, i.e., the imaginal discs, which undergo a rapid differentiation during metamorphosis. Imaginal discs-derived structures, like wings, are built through the action of genes under precise regulation. RESULTS We analyzed 30 honeybee transcriptomes in the search for the gene expression needed for wings and thoracic dorsum construction from the larval wing discs primordia. Analyses were carried out before, during, and after the metamorphic molt and using worker and queen castes. Our RNA-seq libraries revealed 13,202 genes, representing 86.2% of the honeybee annotated genes. Gene Ontology analysis revealed functional terms that were caste-specific or shared by workers and queens. Genes expressed in wing discs and descendant structures showed differential expression profiles dynamics in premetamorphic, metamorphic and postmetamorphic developmental phases, and also between castes. At the metamorphic molt, when ecdysteroids peak, the wing buds of workers showed maximal gene upregulation comparatively to queens, thus underscoring differences in gene expression between castes at the height of the larval-pupal transition. Analysis of small RNA libraries of wing buds allowed us to build miRNA-mRNA interaction networks to predict the regulation of genes expressed during wing discs development. CONCLUSION Together, these data reveal gene expression dynamics leading to wings and thoracic dorsum formation from the wing discs, besides highlighting caste-specific differences during wing discs metamorphosis.
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Affiliation(s)
- Michelle Prioli Miranda Soares
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14049-900, Ribeirão Preto, SP, Brazil
| | - Daniel Guariz Pinheiro
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho, Jaboticabal, SP, Brazil
| | | | - Zilá Luz Paulino Simões
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14040-901, Ribeirão Preto, SP, Brazil
| | - Márcia Maria Gentile Bitondi
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14040-901, Ribeirão Preto, SP, Brazil.
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17
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Abstract
The field of molecular embryology started around 1990 by identifying new genes and analyzing their functions in early vertebrate embryogenesis. Those genes encode transcription factors, signaling molecules, their regulators, etc. Most of those genes are relatively highly expressed in specific regions or exhibit dramatic phenotypes when ectopically expressed or mutated. This review focuses on one of those genes, Lim1/Lhx1, which encodes a transcription factor. Lim1/Lhx1 is a member of the LIM homeodomain (LIM-HD) protein family, and its intimate partner, Ldb1/NLI, binds to two tandem LIM domains of LIM-HDs. The most ancient LIM-HD protein and its partnership with Ldb1 were innovated in the metazoan ancestor by gene fusion combining LIM domains and a homeodomain and by creating the LIM domain-interacting domain (LID) in ancestral Ldb, respectively. The LIM domain has multiple interacting interphases, and Ldb1 has a dimerization domain (DD), the LID, and other interacting domains that bind to Ssbp2/3/4 and the boundary factor, CTCF. By means of these domains, LIM-HD-Ldb1 functions as a hub protein complex, enabling more intricate and elaborate gene regulation. The common, ancestral role of LIM-HD proteins is neuron cell-type specification. Additionally, Lim1/Lhx1 serves crucial roles in the gastrula organizer and in kidney development. Recent studies using Xenopus embryos have revealed Lim1/Lhx1 functions and regulatory mechanisms during development and regeneration, providing insight into evolutionary developmental biology, functional genomics, gene regulatory networks, and regenerative medicine. In this review, we also discuss recent progress at unraveling participation of Ldb1, Ssbp, and CTCF in enhanceosomes, long-distance enhancer-promoter interactions, and trans-interactions between chromosomes.
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Affiliation(s)
- Yuuri Yasuoka
- Laboratory for Comprehensive Genomic Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan.
| | - Masanori Taira
- Department of Biological Sciences, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan.
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18
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DaCrema D, Bhandari R, Karanja F, Yano R, Halme A. Ecdysone regulates the Drosophila imaginal disc epithelial barrier, determining the length of regeneration checkpoint delay. Development 2021; 148:dev.195057. [PMID: 33658221 DOI: 10.1242/dev.195057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 02/15/2021] [Indexed: 02/06/2023]
Abstract
Regeneration of Drosophila imaginal discs, larval precursors to adult tissues, activates a regeneration checkpoint that coordinates regenerative growth with developmental progression. This regeneration checkpoint results from the release of the relaxin-family peptide Dilp8 from regenerating imaginal tissues. Secreted Dilp8 protein is detected within the imaginal disc lumen, in which it is separated from its receptor target Lgr3, which is expressed in the brain and prothoracic gland, by the disc epithelial barrier. Here, we demonstrate that following damage the imaginal disc epithelial barrier limits Dilp8 signaling and the duration of regeneration checkpoint delay. We also find that the barrier becomes increasingly impermeable to the transepithelial diffusion of labeled dextran during the second half of the third instar. This change in barrier permeability is driven by the steroid hormone ecdysone and correlates with changes in localization of Coracle, a component of the septate junctions that is required for the late-larval impermeable epithelial barrier. Based on these observations, we propose that the imaginal disc epithelial barrier regulates the duration of the regenerative checkpoint, providing a mechanism by which tissue function can signal the completion of regeneration.
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Affiliation(s)
- Danielle DaCrema
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22902, USA
| | - Rajan Bhandari
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22902, USA
| | - Faith Karanja
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22902, USA
| | - Ryunosuke Yano
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22902, USA
| | - Adrian Halme
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22902, USA
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19
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Hu Y, Moczek AP. Wing serial homologues and the diversification of insect outgrowths: insights from the pupae of scarab beetles. Proc Biol Sci 2021; 288:20202828. [PMID: 33467999 DOI: 10.1098/rspb.2020.2828] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Modification of serially homologous structures is a common avenue towards functional innovation in developmental evolution, yet ancestral affinities among serial homologues may be obscured as structure-specific modifications accumulate over time. We sought to assess the degree of homology to wings of three types of body wall projections commonly observed in scarab beetles: (i) the dorsomedial support structures found on the second and third thoracic segments of pupae, (ii) the abdominal support structures found bilaterally in most abdominal segments of pupae, and (iii) the prothoracic horns which depending on species and sex may be restricted to pupae or also found in adults. We functionally investigated 14 genes within, as well as two genes outside, the canonical wing gene regulatory network to compare and contrast their role in the formation of each of the three presumed wing serial homologues. We found 11 of 14 wing genes to be functionally required for the proper formation of lateral and dorsal support structures, respectively, and nine for the formation of prothoracic horns. At the same time, we document multiple instances of divergence in gene function across our focal structures. Collectively, our results support the hypothesis that dorsal and lateral support structures as well as prothoracic horns share a developmental origin with insect wings. Our findings suggest that the morphological and underlying gene regulatory diversification of wing serial homologues across species, life stages and segments has contributed significantly to the extraordinary diversity of arthropod appendages and outgrowths.
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Affiliation(s)
- Yonggang Hu
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Armin P Moczek
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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20
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Nagarkar S, Wasnik R, Govada P, Cohen S, Shashidhara LS. Promoter Proximal Pausing Limits Tumorous Growth Induced by the Yki Transcription Factor in Drosophila. Genetics 2020; 216:67-77. [PMID: 32737120 PMCID: PMC7463282 DOI: 10.1534/genetics.120.303419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/27/2020] [Indexed: 12/15/2022] Open
Abstract
Promoter proximal pausing (PPP) of RNA polymerase II has emerged as a crucial rate-limiting step in the regulation of gene expression. Regulation of PPP is brought about by complexes 7SK snRNP, P-TEFb (Cdk9/cycT), and the negative elongation factor (NELF), which are highly conserved from Drosophila to humans. Here, we show that RNAi-mediated depletion of bin3 or Hexim of the 7SK snRNP complex or depletion of individual components of the NELF complex enhances Yki-driven growth, leading to neoplastic transformation of Drosophila wing imaginal discs. We also show that increased CDK9 expression cooperates with Yki in driving neoplastic growth. Interestingly, overexpression of CDK9 on its own or in the background of depletion of one of the components of 7SK snRNP or the NELF complex necessarily, and specifically, needed Yki overexpression to cause tumorous growth. Genome-wide gene expression analyses suggested that deregulation of protein homeostasis is associated with tumorous growth of wing imaginal discs. As both Fat/Hippo/Yki pathway and PPP are highly conserved, our observations may provide insights into mechanisms of oncogenic function of YAP-the ortholog of Yki in humans.
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Affiliation(s)
- Sanket Nagarkar
- Indian Institute of Science Education and Research (IISER), Pashan, Pune 411008
| | - Ruchi Wasnik
- Indian Institute of Science Education and Research (IISER), Pashan, Pune 411008
| | - Pravallika Govada
- Indian Institute of Science Education and Research (IISER), Pashan, Pune 411008
| | - Stephen Cohen
- Department of Cellular and Molecular Medicine, University of Copenhagen, 2200N, Denmark
| | - L S Shashidhara
- Indian Institute of Science Education and Research (IISER), Pashan, Pune 411008
- Ashoka University, Sonepat, Haryana 131029, India
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21
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Zappia MP, de Castro L, Ariss MM, Jefferson H, Islam AB, Frolov MV. A cell atlas of adult muscle precursors uncovers early events in fibre-type divergence in Drosophila. EMBO Rep 2020; 21:e49555. [PMID: 32815271 PMCID: PMC7534622 DOI: 10.15252/embr.201949555] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 07/12/2020] [Accepted: 07/24/2020] [Indexed: 12/31/2022] Open
Abstract
In Drosophila, the wing disc‐associated muscle precursor cells give rise to the fibrillar indirect flight muscles (IFM) and the tubular direct flight muscles (DFM). To understand early transcriptional events underlying this muscle diversification, we performed single‐cell RNA‐sequencing experiments and built a cell atlas of myoblasts associated with third instar larval wing disc. Our analysis identified distinct transcriptional signatures for IFM and DFM myoblasts that underlie the molecular basis of their divergence. The atlas further revealed various states of differentiation of myoblasts, thus illustrating previously unappreciated spatial and temporal heterogeneity among them. We identified and validated novel markers for both IFM and DFM myoblasts at various states of differentiation by immunofluorescence and genetic cell‐tracing experiments. Finally, we performed a systematic genetic screen using a panel of markers from the reference cell atlas as an entry point and found a novel gene, Amalgam which is functionally important in muscle development. Our work provides a framework for leveraging scRNA‐seq for gene discovery and details a strategy that can be applied to other scRNA‐seq datasets.
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Affiliation(s)
- Maria Paula Zappia
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Lucia de Castro
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Majd M Ariss
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Holly Jefferson
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Abul Bmmk Islam
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Maxim V Frolov
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
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22
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Wang J, Dahmann C. Establishing compartment boundaries in Drosophila wing imaginal discs: An interplay between selector genes, signaling pathways and cell mechanics. Semin Cell Dev Biol 2020; 107:161-169. [PMID: 32732129 DOI: 10.1016/j.semcdb.2020.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/13/2020] [Accepted: 07/14/2020] [Indexed: 01/02/2023]
Abstract
The partitioning of cells into groups or 'compartments' separated by straight and sharp boundaries is important for tissue formation in animal development. Cells from neighboring compartments are characterized by distinct fates and functions and their continuous separation at compartment boundaries maintains proper tissue organization. Signaling across compartment boundaries can induce the local expression of morphogens that in turn direct growth and patterning of the surrounding cells. Compartment boundaries play therefore an important role in tissue development. Compartment boundaries were first identified in the early 1970s in the Drosophila wing. Here, we review the role of compartment boundaries in growth and patterning of the developing wing and then discuss the genetic and physical mechanisms underlying cell separation at compartment boundaries in this tissue.
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Affiliation(s)
- Jing Wang
- Institute of Genetics, Technische Universität Dresden, 01062 Dresden, Germany
| | - Christian Dahmann
- Institute of Genetics, Technische Universität Dresden, 01062 Dresden, Germany; Cluster of Excellence Physics of Life, Technische Universität Dresden, 01062 Dresden, Germany.
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23
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George S, Palli SR. Histone Deacetylase 11 Knockdown Blocks Larval Development and Metamorphosis in the Red Flour Beetle, Tribolium castaneum. Front Genet 2020; 11:683. [PMID: 32719718 PMCID: PMC7348043 DOI: 10.3389/fgene.2020.00683] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/04/2020] [Indexed: 12/31/2022] Open
Abstract
Post-translational modifications (PTM) such as methylation, acetylation, phosphorylation, and ubiquitination of histones and other proteins regulate expression of genes. The acetylation levels of these proteins are determined by the balance of expression of histone acetyltransferase (HATs) and histone deacetylases (HDACs). We recently reported that class I HDACs (HDAC1 and HDAC3) play important roles in juvenile hormone (JH) suppression of metamorphosis in the red flour beetle, Tribolium castaneum. Here, we report on the function of a single class IV HDAC member, HDAC11. Injection of dsRNA targeting T. castaneum HDAC11 gene into newly molted last instar larvae induced knockdown of the target gene and arrested larval development and prevented metamorphosis into the pupal stage. Dark melanized areas were detected in larvae that showed developmental arrest and mortality. Developmental expression studies showed an increase in HDAC11 mRNA levels beginning at the end of the penultimate larval stage. These higher levels were maintained during the final instar larval and pupal stages. A JH analog, hydroprene, suppressed HDAC11 expression in the larvae. Sequencing of RNA isolated from control and dsHDAC11 injected larvae identified several differentially expressed genes, including those involved in JH action, ecdysone response, and melanization. The acetylation levels of core histones showed an increase in TcA cells exposed to dsHDAC11. Also, an increase in histone H3 acetylation, specifically H3K9, H3K18 and H3K27, were detected in HDAC11 knockdown larvae. These studies report the function of HDAC11 in insects other than Drosophila for the first time and show that HDAC11 influences the acetylation levels of histones and expression of multiple genes involved in T. castaneum larval development.
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Affiliation(s)
- Smitha George
- Department of Entomology, University of Kentucky, Lexington, KY, United States
| | - Subba Reddy Palli
- Department of Entomology, University of Kentucky, Lexington, KY, United States
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24
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Klipa O, Hamaratoglu F. Cell elimination strategies upon identity switch via modulation of apterous in Drosophila wing disc. PLoS Genet 2019; 15:e1008573. [PMID: 31877129 PMCID: PMC6952109 DOI: 10.1371/journal.pgen.1008573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/09/2020] [Accepted: 12/17/2019] [Indexed: 12/04/2022] Open
Abstract
The ability to establish spatial organization is an essential feature of any developing tissue and is achieved through well-defined rules of cell-cell communication. Maintenance of this organization requires elimination of cells with inappropriate positional identity, a poorly understood phenomenon. Here we studied mechanisms regulating cell elimination in the context of a growing tissue, the Drosophila wing disc and its dorsal determinant Apterous. Systematic analysis of apterous mutant clones along with their twin spots shows that they are eliminated from the dorsal compartment via three different mechanisms: relocation to the ventral compartment, basal extrusion, and death, depending on the position of the clone in the wing disc. We find that basal extrusion is the main elimination mechanism in the hinge, whereas apoptosis dominates in the pouch and in the notum. In the absence of apoptosis, extrusion takes over to ensure clearance in all regions. Notably, clones in the hinge grow larger than those in the pouch, emphasizing spatial differences. Mechanistically, we find that limiting cell division within the clones does not prevent their extrusion. Indeed, even clones of one or two cells can be extruded basally, demonstrating that the clone size is not the main determinant of the elimination mechanism to be used. Overall, we revealed three elimination mechanisms and their spatial biases for preserving pattern in a growing organ. As development proceeds, cells become more specialized and the compartmentalization ensures spatial separation of the specialized cells. This process of pattern formation is rather well understood. How the pattern is maintained afterwards though is largely unknown. Using the Drosophila wing disc as a model organ, we examined what happens to dorsal cells if they lose their dorsal identity. Formerly, it was shown that these cells are eliminated from the dorsal compartment via apoptosis or through relocation to the ventral compartment. Here we show that a third mode of elimination, basal extrusion, also contributes to their clearing. We quantified, for the first time, contributions of each mechanism and discovered a regional bias in their operation. Importantly, if apoptosis is blocked, basal extrusion takes over to ensure clearance from all regions. Recent modeling approaches suggested that there is a lower limit to the clone size for extrusion. Therefore, we tested the hypothesis that the choice of elimination mechanism may be dictated by the clone size. We prevented cell divisions within the clones to be eliminated and found that even 1–2 cell clones readily underwent basal extrusion, demonstrating that there is no lower limit to the clone size for extrusion.
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Affiliation(s)
- Olga Klipa
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Fisun Hamaratoglu
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
- * E-mail:
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Co-option of wing-patterning genes underlies the evolution of the treehopper helmet. Nat Ecol Evol 2019; 4:250-260. [DOI: 10.1038/s41559-019-1054-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/25/2019] [Indexed: 12/18/2022]
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Yorkie and JNK Control Tumorigenesis in Drosophila Cells with Cytokinesis Failure. Cell Rep 2019; 23:1491-1503. [PMID: 29719260 DOI: 10.1016/j.celrep.2018.04.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 03/14/2018] [Accepted: 03/30/2018] [Indexed: 01/23/2023] Open
Abstract
Cytokinesis failure may result in the formation of polyploid cells, and subsequent mitosis can lead to aneuploidy and tumor formation. Tumor suppressor mechanisms limiting the oncogenic potential of these cells have been described. However, the universal applicability of these tumor-suppressive barriers remains controversial. Here, we use Drosophila epithelial cells to investigate the consequences of cytokinesis failure in vivo. We report that cleavage defects trigger the activation of the JNK pathway, leading to downregulation of the inhibitor of apoptosis DIAP1 and programmed cell death. Yorkie overcomes the tumor-suppressive role of JNK and induces neoplasia. Yorkie regulates the cell cycle phosphatase Cdc25/string, which drives tumorigenesis in a context of cytokinesis failure. These results highlight the functional significance of the JNK pathway in epithelial cells with defective cytokinesis and elucidate a mechanism used by emerging tumor cells to bypass this tumor-suppressive barrier and develop into tumors.
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A refutation to 'A new A-P compartment boundary and organizer in holometabolous insect wings'. Sci Rep 2019; 9:7049. [PMID: 31065001 PMCID: PMC6505030 DOI: 10.1038/s41598-019-42668-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/05/2019] [Indexed: 12/25/2022] Open
Abstract
We respond to a recent report by Abbasi and Marcus who present two main findings: first they argue that there is an organiser and a compartment boundary within the posterior compartment of the butterfly wing. Second, they present evidence for a previously undiscovered lineage boundary near wing vein 5 in Drosophila, a boundary that delineates a "far posterior" compartment. Clones of cells were marked with the yellow mutation and they reported that these clones always fail to cross a line close to vein 5 on the Drosophila wing. In our hands yellow proved an unusable marker for clones in the wing blade and therefore we reexamined the matter. We marked clones of cells with multiple wing hairs or forked and found a substantial proportion of these clones cross the proposed lineage boundary near vein 5, in conflict with their findings and conclusion. As internal controls we showed that these same clones respect the other two well established compartment boundaries: the anteroposterior compartment boundary is always respected. The dorsoventral boundary is mostly respected, and is crossed only by clones that are induced early in development, consistent with many reports. We question the validity of Abbasi and Marcus' conclusions regarding the butterfly wing but present no new data.Arising from: R. Abbasi and J. M. Marcus Sci. Rep. 7, 16337 (2017); https://doi.org/10.1038/s41598-017-16553-5 .
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Mayumi K, Danielle B, Lisa L, Alexanda F, Nathan C, Boyang Q, Ahmad ST, Bernard P. The Drosophila apterous 56f mutation impairs circadian locomotor activity. BIOL RHYTHM RES 2019; 50:375-388. [PMID: 31011241 PMCID: PMC6474370 DOI: 10.1080/09291016.2018.1447353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We investigated effects of apterous mutation ap56f on circadian locomotor activity, eclosion rhythms, and transcript levels of period and timeless in Drosophila. We investigated circadian locomotor activity and eclosion rhythms in ap 56fand wild-type flies, their F1 and F2 offspring, and wingless vestigial mutants and show that ap 56f disrupts circadian locomotor rhythms in a genetically recessive manner, that is not caused by the absence of wings. The ap blt strain also showed impaired circadian activity rhythms, providing independent evidence for a significant role of apterous in circadian locomotor rhythm expression. The ap 56f mutation did not disrupt a circadian eclosion rhythm or rhythmic expression of the period and timeless clock genes, indicating that apterous is not essential for circadian clock function, but is necessary for coupling locomotor activity to a circadian clock. Timeless transcription was reduced in ap 56f flies in 12:12 LD, suggesting that apterous may modulate core clock gene expression.
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Affiliation(s)
- Kohiyama Mayumi
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 917-715-7270
| | - Bonser Danielle
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 518-223-2790
| | - Leung Lisa
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 617-910-7669
| | - Fall Alexanda
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 845-803-3591
| | - Canada Nathan
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 770-359-7123
| | - Qu Boyang
- Biology Department, Colby College, Waterville, ME USA, , 207-616-6117
| | - S Tariq Ahmad
- Biology Department, Colby College, Waterville, ME USA, , 207-859-5722
| | - Possidente Bernard
- Biology Department, Skidmore College, Saratoga Springs, NY USA, , 518-580-5082
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The genes expression difference between winged and wingless bird cherry-oat aphid Rhopalosiphum padi based on transcriptomic data. Sci Rep 2019; 9:4754. [PMID: 30894649 PMCID: PMC6426873 DOI: 10.1038/s41598-019-41348-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 01/23/2019] [Indexed: 01/05/2023] Open
Abstract
Aphids produce wing and wingless morphs, depending on the environmental conditions during their complex life cycles. Wing and wingless variations play an important role in migration and host alternation, affecting the migration and host alternation processes. Several transcriptional studies have concentrated on aphids and sought to determine how an organism perceives environmental cues and responds in a plastic manner, but the underlying mechanisms have remained unclear. Therefore, to better understand the molecular mechanisms underlying the wing polyphenism of this fascinating phenomenon, we provide the first report concerning the wing development of aphids in bird cherry-oat aphid Rhopalosiphum padi with comparative transcriptional analysis of all the developmental stages by RNA-Seq. We identified several candidate genes related to biogenic amines and hormones that may be specifically involved in wing development. Moreover, we found that the third instar stage might be a critical stage for visibility of alternative morphs as well as changes in the expression of thirty-three genes associated with wing development. Several genes, i.e., Wnt2, Fng, Uba1, Hh, Foxo, Dpp, Brk, Ap, Dll, Hth, Tsh, Nub, Scr, Antp, Ubx, Asc, Srf and Fl, had different expression levels in different developmental stages and may play important roles in regulating wing polyphenism.
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Prakash A, Monteiro A. apterous A specifies dorsal wing patterns and sexual traits in butterflies. Proc Biol Sci 2019; 285:rspb.2017.2685. [PMID: 29467265 PMCID: PMC5832707 DOI: 10.1098/rspb.2017.2685] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/29/2018] [Indexed: 01/05/2023] Open
Abstract
Butterflies have evolved different colour patterns on their dorsal and ventral wing surfaces to serve different signalling functions, yet the developmental mechanisms controlling surface-specific patterning are still unknown. Here, we mutate both copies of the transcription factor apterous in Bicyclus anynana butterflies using CRISPR/Cas9 and show that apterous A, expressed dorsally, functions both as a repressor and modifier of ventral wing colour patterns, as well as a promoter of dorsal sexual ornaments in males. We propose that the surface-specific diversification of wing patterns in butterflies proceeded via the co-option of apterous A or its downstream effectors into various gene regulatory networks involved in the differentiation of discrete wing traits. Further, interactions between apterous and sex-specific factors such as doublesex may have contributed to the origin of sexually dimorphic surface-specific patterns. Finally, we discuss the evolution of eyespot number diversity in the family Nymphalidae within the context of developmental constraints due to apterous regulation.
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Affiliation(s)
- Anupama Prakash
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore
| | - Antónia Monteiro
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore .,Yale-NUS College, Singapore
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Ruiz-Losada M, Blom-Dahl D, Córdoba S, Estella C. Specification and Patterning of Drosophila Appendages. J Dev Biol 2018; 6:jdb6030017. [PMID: 30011921 PMCID: PMC6162442 DOI: 10.3390/jdb6030017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 07/10/2018] [Accepted: 07/12/2018] [Indexed: 02/06/2023] Open
Abstract
Appendages are external projections of the body that serve the animal for locomotion, feeding, or environment exploration. The appendages of the fruit fly Drosophilamelanogaster are derived from the imaginal discs, epithelial sac-like structures specified in the embryo that grow and pattern during larva development. In the last decades, genetic and developmental studies in the fruit fly have provided extensive knowledge regarding the mechanisms that direct the formation of the appendages. Importantly, many of the signaling pathways and patterning genes identified and characterized in Drosophila have similar functions during vertebrate appendage development. In this review, we will summarize the genetic and molecular mechanisms that lead to the specification of appendage primordia in the embryo and their posterior patterning during imaginal disc development. The identification of the regulatory logic underlying appendage specification in Drosophila suggests that the evolutionary origin of the insect wing is, in part, related to the development of ventral appendages.
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Affiliation(s)
- Mireya Ruiz-Losada
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM/CSIC), Nicolás Cabrera 1, 28049 Madrid, Spain.
| | - David Blom-Dahl
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM/CSIC), Nicolás Cabrera 1, 28049 Madrid, Spain.
| | - Sergio Córdoba
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM/CSIC), Nicolás Cabrera 1, 28049 Madrid, Spain.
| | - Carlos Estella
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid (UAM/CSIC), Nicolás Cabrera 1, 28049 Madrid, Spain.
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Kairamkonda S, Nongthomba U. Beadex, a Drosophila LIM domain only protein, function in follicle cells is essential for egg development and fertility. Exp Cell Res 2018; 367:97-103. [PMID: 29580687 DOI: 10.1016/j.yexcr.2018.03.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 11/25/2022]
Abstract
LIM domain, constituted by two tandem C2H2 zinc finger motif, proteins regulate several biological processes. They are usually found associated with various functional domains like Homeodomain, kinase domain and other protein binding domains. LIM proteins that are devoid of other domains are called LIM only proteins (LMO). LMO proteins were first identified in humans and are implicated in development and oncogenesis. They regulate various cell specifications by regulating the activity of respective transcriptional complexes. The Drosophila LMO protein (dLMO), Beadex (Bx), regulates various developmental processes like wing margin development and bristle development. It also regulates Drosophila behavior in response to cocaine and ethanol. We have previously generated Bx null flies and shown its essential function in neurons for multiple aspects of female reproduction. However, it was not known whether Bx affects reproduction through its independent function in ovaries. In this paper we show that female flies null for Bx lay eggs with multiple defects. Further, through knock down studies we demonstrate that function of Bx in follicle cells is required for normal egg development. We also show that function of Bx is particularly required in border cells for Drosophila fertility.
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Affiliation(s)
- Subhash Kairamkonda
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
| | - Upendra Nongthomba
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India.
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Reciprocal Negative Regulation Between Lmx1a and Lmo4 Is Required for Inner Ear Formation. J Neurosci 2018; 38:5429-5440. [PMID: 29769265 PMCID: PMC5990987 DOI: 10.1523/jneurosci.2484-17.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 02/07/2018] [Accepted: 02/11/2018] [Indexed: 02/07/2023] Open
Abstract
LIM-domain containing transcription factors (LIM-TFs) are conserved factors important for embryogenesis. The specificity of these factors in transcriptional regulation is conferred by the complexes that they form with other proteins such as LIM-domain-binding (Ldb) proteins and LIM-domain only (LMO) proteins. Unlike LIM-TFs, these proteins do not bind DNA directly. LMO proteins are negative regulators of LIM-TFs and function by competing with LIM-TFs for binding to Ldb's. Although the LIM-TF Lmx1a is expressed in the developing mouse hindbrain, which provides many of the extrinsic signals for inner ear formation, conditional knock-out embryos of both sexes show that the inner ear source of Lmx1a is the major contributor of ear patterning. In addition, we have found that the reciprocal interaction between Lmx1a and Lmo4 (a LMO protein within the inner ear) mediates the formation of both vestibular and auditory structures. Lmo4 negatively regulates Lmx1a to form the three sensory cristae, the anterior semicircular canal, and the shape of the utricle in the vestibule. Furthermore, this negative regulation blocks ectopic sensory formation in the cochlea. In contrast, Lmx1a negatively regulates Lmo4 in mediating epithelial resorption of the canal pouch, which gives rise to the anterior and posterior semicircular canals. We also found that Lmx1a is independently required for the formation of the endolymphatic duct and hair cells in the basal cochlear region. SIGNIFICANCE STATEMENT The mammalian inner ear is a structurally complex organ responsible for detecting sound and maintaining balance. Failure to form the intricate 3D structure of this organ properly during development most likely will result in sensory deficits on some level. Here, we provide genetic evidence that a transcription factor, Lmx1a, interacts with its negative regulator, Lmo4, to pattern various vestibular and auditory components of the mammalian inner ear. Identifying these key molecules that mediate formation of this important sensory organ will be helpful for designing strategies and therapeutics to alleviate hearing loss and balance disorders.
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Abstract
A hundred years after Lhx2 ortholog apterous was identified as a critical regulator of wing development in Drosophila, LIM-HD gene family members have proved to be versatile and powerful components of the molecular machinery that executes the blueprint of embryogenesis across vertebrate and invertebrate species. Here, we focus on the spatio-temporally varied functions of LIM-homeodomain transcription factor LHX2 in the developing mouse forebrain. Right from its earliest known role in telencephalic and eye field patterning, to the control of the neuron-glia cell fate switch, and the regulation of axon pathfinding and dendritic arborization in late embryonic stages, LHX2 has been identified as a fundamental, temporally dynamic, always necessary, and often sufficient factor in a range of critical developmental phenomena. While Lhx2 mutant phenotypes have been characterized in detail in multiple brain structures, only recently have we advanced in our understanding of the molecular mechanisms by which this factor acts. Common themes emerge from how this multifunctional molecule controls a range of developmental steps in distinct forebrain structures. Examining these shared features, and noting unique aspects of LHX2 function is likely to inform our understanding of how a single factor can bring about a diversity of effects and play central and critical roles across systems and stages. The parallels in LHX2 and APTEROUS functions, and the protein complexes they participate in, offer insights into evolutionary strategies that conserve tool kits and deploy them to play new, yet familiar roles in species separated by hundreds of millions of years.
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Affiliation(s)
- Shen-Ju Chou
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Shubha Tole
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India.
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Jiggins CD, Wallbank RWR, Hanly JJ. Waiting in the wings: what can we learn about gene co-option from the diversification of butterfly wing patterns? Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2015.0485. [PMID: 27994126 DOI: 10.1098/rstb.2015.0485] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2016] [Indexed: 12/11/2022] Open
Abstract
A major challenge is to understand how conserved gene regulatory networks control the wonderful diversity of form that we see among animals and plants. Butterfly wing patterns are an excellent example of this diversity. Butterfly wings form as imaginal discs in the caterpillar and are constructed by a gene regulatory network, much of which is conserved across the holometabolous insects. Recent work in Heliconius butterflies takes advantage of genomic approaches and offers insights into how the diversification of wing patterns is overlaid onto this conserved network. WntA is a patterning morphogen that alters spatial information in the wing. Optix is a transcription factor that acts later in development to paint specific wing regions red. Both of these loci fit the paradigm of conserved protein-coding loci with diverse regulatory elements and developmental roles that have taken on novel derived functions in patterning wings. These discoveries offer insights into the 'Nymphalid Ground Plan', which offers a unifying hypothesis for pattern formation across nymphalid butterflies. These loci also represent 'hotspots' for morphological change that have been targeted repeatedly during evolution. Both convergent and divergent evolution of a great diversity of patterns is controlled by complex alleles at just a few genes. We suggest that evolutionary change has become focused on one or a few genetic loci for two reasons. First, pre-existing complex cis-regulatory loci that already interact with potentially relevant transcription factors are more likely to acquire novel functions in wing patterning. Second, the shape of wing regulatory networks may constrain evolutionary change to one or a few loci. Overall, genomic approaches that have identified wing patterning loci in these butterflies offer broad insight into how gene regulatory networks evolve to produce diversity.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'.
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Affiliation(s)
- Chris D Jiggins
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Richard W R Wallbank
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Joseph J Hanly
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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Deshmukh R, Baral S, Gandhimathi A, Kuwalekar M, Kunte K. Mimicry in butterflies: co-option and a bag of magnificent developmental genetic tricks. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 28913870 DOI: 10.1002/wdev.291] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 07/04/2017] [Accepted: 07/20/2017] [Indexed: 01/05/2023]
Abstract
Butterfly wing patterns are key adaptations that are controlled by remarkable developmental and genetic mechanisms that facilitate rapid evolutionary change. With swift advancements in the fields of genomics and genetic manipulations, identifying the regulators of wing development and mimetic wing patterns has become feasible even in nonmodel organisms such as butterflies. Recent mapping and gene expression studies have identified single switch loci of major effects such as transcription factors and supergenes as the main drivers of adaptive evolution of mimetic and polymorphic butterfly wing patterns. We highlight several of these examples, with emphasis on doublesex, optix, WntA and other dynamic, yet essential, master regulators that control critical color variation and sex-specific traits. Co-option emerges as a predominant theme, where typically embryonic and other early-stage developmental genes and networks have been rewired to regulate polymorphic and sex-limited mimetic wing patterns in iconic butterfly adaptations. Drawing comparisons from our knowledge of wing development in Drosophila, we illustrate the functional space of genes that have been recruited to regulate butterfly wing patterns. We also propose a developmental pathway that potentially results in dorsoventral mismatch in butterfly wing patterns. Such dorsoventrally mismatched color patterns modulate signal components of butterfly wings that are used in intra- and inter-specific communication. Recent advances-fuelled by RNAi-mediated knockdowns and CRISPR/Cas9-based genomic edits-in the developmental genetics of butterfly wing patterns, and the underlying biological diversity and complexity of wing coloration, are pushing butterflies as an emerging model system in ecological genetics and evolutionary developmental biology. WIREs Dev Biol 2018, 7:e291. doi: 10.1002/wdev.291 This article is categorized under: Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms Comparative Development and Evolution > Regulation of Organ Diversity Comparative Development and Evolution > Evolutionary Novelties.
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Affiliation(s)
| | - Saurav Baral
- National Centre for Biological Sciences, Bengaluru, India
| | - A Gandhimathi
- National Centre for Biological Sciences, Bengaluru, India
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Al Khatib A, Siomava N, Iannini A, Posnien N, Casares F. Specific expression and function of the Six3 optix in Drosophila serially homologous organs. Biol Open 2017. [PMID: 28642242 PMCID: PMC5576073 DOI: 10.1242/bio.023606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Organ size and pattern results from the integration of two positional information systems. One global information system, encoded by the Hox genes, links organ type with position along the main body axis. Within specific organs, local information is conveyed by signaling molecules that regulate organ growth and pattern. The mesothoracic (T2) wing and the metathoracic (T3) haltere of Drosophila represent a paradigmatic example of this coordination. The Hox gene Ultrabithorax (Ubx), expressed in the developing T3, selects haltere identity by, among other processes, modulating the production and signaling efficiency of Dpp, a BMP2-like molecule that acts as a major regulator of size and pattern. However, the mechanisms of the Hox-signal integration in this well-studied system are incomplete. Here, we have investigated this issue by studying the expression and function of the Six3 transcription factor optix during Drosophila wing and haltere development. We find that in both organs, Dpp defines the expression domain of optix through repression, and that the specific position of this domain in wing and haltere seems to reflect the differential signaling profile among these organs. We show that optix expression in wing and haltere primordia is conserved beyond Drosophila in other higher diptera. In Drosophila, optix is necessary for the growth of wing and haltere. In the wing, optix is required for the growth of the most anterior/proximal region (the ‘marginal cell’) and for the correct formation of sensory structures along the proximal anterior wing margin; the halteres of optix mutants are also significantly reduced. In addition, in the haltere, optix is necessary for the suppression of sensory bristles. Summary: The position of the Six3 optix is regulated by the Dpp pathway during wing and haltere development, and controls the size of both serially homologous organs.
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Affiliation(s)
- Amer Al Khatib
- Department of Gene Regulation and Morphogenesis, Andalusian Centre for Developmental Biology (CABD), CSIC-Pablo de Olavide University-JA, 41013 Seville, Spain.,Department of Biology, University of Florence, I-50019, Florence, Italy
| | - Natalia Siomava
- Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Goettingen Center for Molecular Biosciences (GZMB), Department of Developmental Biology, University of Goettingen, 37077 Goettingen, Germany
| | - Antonella Iannini
- Department of Gene Regulation and Morphogenesis, Andalusian Centre for Developmental Biology (CABD), CSIC-Pablo de Olavide University-JA, 41013 Seville, Spain
| | - Nico Posnien
- Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Goettingen Center for Molecular Biosciences (GZMB), Department of Developmental Biology, University of Goettingen, 37077 Goettingen, Germany
| | - Fernando Casares
- Department of Gene Regulation and Morphogenesis, Andalusian Centre for Developmental Biology (CABD), CSIC-Pablo de Olavide University-JA, 41013 Seville, Spain
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Abstract
Although the insect wing is a textbook example of morphological novelty, the origin of insect wings remains a mystery and is regarded as a chief conundrum in biology. Centuries of debates have culminated into two prominent hypotheses: the tergal origin hypothesis and the pleural origin hypothesis. However, between these two hypotheses, there is little consensus in regard to the origin tissue of the wing as well as the evolutionary route from the origin tissue to the functional flight device. Recent evolutionary developmental (evo-devo) studies have shed new light on the origin of insect wings. A key concept in these studies is “serial homology”. In this review, we discuss how the wing serial homologs identified in recent evo-devo studies have provided a new angle through which this century-old conundrum can be explored. We also review what we have learned so far from wing serial homologs and discuss what we can do to go beyond simply identifying wing serial homologs and delve further into the developmental and genetic mechanisms that have facilitated the evolution of insect wings.
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Affiliation(s)
- Yoshinori Tomoyasu
- Department of Biology, Miami University, Pearson Hall, 700E High Street, Oxford, OH 45056, USA
| | - Takahiro Ohde
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan.,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Courtney Clark-Hachtel
- Department of Biology, Miami University, Pearson Hall, 700E High Street, Oxford, OH 45056, USA
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Fisher YE, Yang HH, Isaacman-Beck J, Xie M, Gohl DM, Clandinin TR. FlpStop, a tool for conditional gene control in Drosophila. eLife 2017; 6. [PMID: 28211790 PMCID: PMC5342825 DOI: 10.7554/elife.22279] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 02/13/2017] [Indexed: 12/15/2022] Open
Abstract
Manipulating gene function cell type-specifically is a common experimental goal in Drosophila research and has been central to studies of neural development, circuit computation, and behavior. However, current cell type-specific gene disruption techniques in flies often reduce gene activity incompletely or rely on cell division. Here we describe FlpStop, a generalizable tool for conditional gene disruption and rescue in post-mitotic cells. In proof-of-principle experiments, we manipulated apterous, a regulator of wing development. Next, we produced conditional null alleles of Glutamic acid decarboxylase 1 (Gad1) and Resistant to dieldrin (Rdl), genes vital for GABAergic neurotransmission, as well as cacophony (cac) and paralytic (para), voltage-gated ion channels central to neuronal excitability. To demonstrate the utility of this approach, we manipulated cac in a specific visual interneuron type and discovered differential regulation of calcium signals across subcellular compartments. Thus, FlpStop will facilitate investigations into the interactions between genes, circuits, and computation. DOI:http://dx.doi.org/10.7554/eLife.22279.001
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Affiliation(s)
- Yvette E Fisher
- Department of Neurobiology, Stanford University, Stanford, United States
| | - Helen H Yang
- Department of Neurobiology, Stanford University, Stanford, United States
| | | | - Marjorie Xie
- Department of Neurobiology, Stanford University, Stanford, United States
| | - Daryl M Gohl
- Department of Neurobiology, Stanford University, Stanford, United States
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Stanford, United States
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40
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Modulation of light-driven arousal by LIM-homeodomain transcription factor Apterous in large PDF-positive lateral neurons of the Drosophila brain. Sci Rep 2016; 6:37255. [PMID: 27853240 PMCID: PMC5112534 DOI: 10.1038/srep37255] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/26/2016] [Indexed: 11/29/2022] Open
Abstract
Apterous (Ap), the best studied LIM-homeodomain transcription factor in Drosophila, cooperates with the cofactor Chip (Chi) to regulate transcription of specific target genes. Although Ap regulates various developmental processes, its function in the adult brain remains unclear. Here, we report that Ap and Chi in the neurons expressing PDF, a neuropeptide, play important roles in proper sleep/wake regulation in adult flies. PDF-expressing neurons consist of two neuronal clusters: small ventral-lateral neurons (s-LNvs) acting as the circadian pacemaker and large ventral-lateral neurons (l-LNvs) regulating light-driven arousal. We identified that Ap localizes to the nuclei of s-LNvs and l-LNvs. In light-dark (LD) cycles, RNAi knockdown or the targeted expression of dominant-negative forms of Ap or Chi in PDF-expressing neurons or l-LNvs promoted arousal. In contrast, in constant darkness, knockdown of Ap in PDF-expressing neurons did not promote arousal, indicating that a reduced Ap function in PDF-expressing neurons promotes light-driven arousal. Furthermore, Ap expression in l-LNvs showed daily rhythms (peaking at midnight), which are generated by a direct light-dependent mechanism rather than by the endogenous clock. These results raise the possibility that the daily oscillation of Ap expression in l-LNvs may contribute to the buffering of light-driven arousal in wild-type flies.
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Michel M, Aliee M, Rudolf K, Bialas L, Jülicher F, Dahmann C. The Selector Gene apterous and Notch Are Required to Locally Increase Mechanical Cell Bond Tension at the Drosophila Dorsoventral Compartment Boundary. PLoS One 2016; 11:e0161668. [PMID: 27552097 PMCID: PMC4995041 DOI: 10.1371/journal.pone.0161668] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/09/2016] [Indexed: 11/25/2022] Open
Abstract
The separation of cells with distinct fates and functions is important for tissue and organ formation during animal development. Regions of different fates within tissues are often separated from another along straight boundaries. These compartment boundaries play a crucial role in tissue patterning and growth by stably positioning organizers. In Drosophila, the wing imaginal disc is subdivided into a dorsal and a ventral compartment. Cells of the dorsal, but not ventral, compartment express the selector gene apterous. Apterous expression sets in motion a gene regulatory cascade that leads to the activation of Notch signaling in a few cell rows on either side of the dorsoventral compartment boundary. Both Notch and apterous mutant clones disturb the separation of dorsal and ventral cells. Maintenance of the straight shape of the dorsoventral boundary involves a local increase in mechanical tension at cell bonds along the boundary. The mechanisms by which cell bond tension is locally increased however remain unknown. Here we use a combination of laser ablation of cell bonds, quantitative image analysis, and genetic mutants to show that Notch and Apterous are required to increase cell bond tension along the dorsoventral compartment boundary. Moreover, clonal expression of the Apterous target gene capricious results in cell separation and increased cell bond tension at the clone borders. Finally, using a vertex model to simulate tissue growth, we find that an increase in cell bond tension at the borders of cell clones, but not throughout the cell clone, can lead to cell separation. We conclude that Apterous and Notch maintain the characteristic straight shape of the dorsoventral compartment boundary by locally increasing cell bond tension.
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Affiliation(s)
- Marcus Michel
- Institute of Genetics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Maryam Aliee
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187, Dresden, Germany
| | - Katrin Rudolf
- Institute of Genetics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Lisa Bialas
- Institute of Genetics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187, Dresden, Germany
- * E-mail: (FJ); (CD)
| | - Christian Dahmann
- Institute of Genetics, Technische Universität Dresden, 01062, Dresden, Germany
- * E-mail: (FJ); (CD)
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Neuronal Cell Fate Specification by the Convergence of Different Spatiotemporal Cues on a Common Terminal Selector Cascade. PLoS Biol 2016; 14:e1002450. [PMID: 27148744 PMCID: PMC4858240 DOI: 10.1371/journal.pbio.1002450] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 04/01/2016] [Indexed: 01/26/2023] Open
Abstract
Specification of the myriad of unique neuronal subtypes found in the nervous system depends upon spatiotemporal cues and terminal selector gene cascades, often acting in sequential combinatorial codes to determine final cell fate. However, a specific neuronal cell subtype can often be generated in different parts of the nervous system and at different stages, indicating that different spatiotemporal cues can converge on the same terminal selectors to thereby generate a similar cell fate. However, the regulatory mechanisms underlying such convergence are poorly understood. The Nplp1 neuropeptide neurons in the Drosophila ventral nerve cord can be subdivided into the thoracic-ventral Tv1 neurons and the dorsal-medial dAp neurons. The activation of Nplp1 in Tv1 and dAp neurons depends upon the same terminal selector cascade: col>ap/eya>dimm>Nplp1. However, Tv1 and dAp neurons are generated by different neural progenitors (neuroblasts) with different spatiotemporal appearance. Here, we find that the same terminal selector cascade is triggered by Kr/pdm>grn in dAp neurons, but by Antp/hth/exd/lbe/cas in Tv1 neurons. Hence, two different spatiotemporal combinations can funnel into a common downstream terminal selector cascade to determine a highly related cell fate. A study of neuropeptide neurons in the Drosophila nervous system reveals that two different combinations of spatiotemporal cues—active in different progenitors—converge on a common terminal selector gene to trigger a similar neuronal subtype identity. A fundamental challenge in developmental neurobiology is to understand how the great diversity of neuronal subtypes is generated during nervous system development. Neuronal subtype cell fate is established in a stepwise manner, starting with spatial and temporal cues that confer distinct identities to neural progenitors and trigger expression of terminal selector genes in the early-born neurons. Terminal selectors are those that determine the final neuronal subtype cell fate. Intriguingly, similar neuronal subtypes can be generated by different progenitors and under the control of different spatiotemporal cues; thus, we wondered how such convergence is achieved. To address this issue, we have decoded the specification of two highly related neuropeptide neurons, which are generated at different locations and time-points in the Drosophila nervous system. We find that two different combinations of spatiotemporal cues, in two different neural progenitors, funnel onto the same terminal selector gene, which in turn activates a shared regulatory cascade, ultimately resulting in the specification of a similar neuronal cell subtype identity.
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Integration of Orthogonal Signaling by the Notch and Dpp Pathways in Drosophila. Genetics 2016; 203:219-40. [PMID: 26975664 PMCID: PMC4858776 DOI: 10.1534/genetics.116.186791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/08/2016] [Indexed: 11/18/2022] Open
Abstract
The transcription factor Suppressor of Hairless and its coactivator, the Notch intracellular domain, are polyglutamine (pQ)-rich factors that target enhancer elements and interact with other locally bound pQ-rich factors. To understand the functional repertoire of such enhancers, we identify conserved regulatory belts with binding sites for the pQ-rich effectors of both Notch and BMP/Dpp signaling, and the pQ-deficient tissue selectors Apterous (Ap), Scalloped (Sd), and Vestigial (Vg). We find that the densest such binding site cluster in the genome is located in the BMP-inducible nab locus, a homolog of the vertebrate transcriptional cofactors NAB1/NAB2 We report three major findings. First, we find that this nab regulatory belt is a novel enhancer driving dorsal wing margin expression in regions of peak phosphorylated Mad in wing imaginal discs. Second, we show that Ap is developmentally required to license the nab dorsal wing margin enhancer (DWME) to read out Notch and Dpp signaling in the dorsal compartment. Third, we find that the nab DWME is embedded in a complex of intronic enhancers, including a wing quadrant enhancer, a proximal wing disc enhancer, and a larval brain enhancer. This enhancer complex coordinates global nab expression via both tissue-specific activation and interenhancer silencing. We suggest that DWME integration of BMP signaling maintains nab expression in proliferating margin descendants that have divided away from Notch-Delta boundary signaling. As such, uniform expression of genes like nab and vestigial in proliferating compartments would typically require both boundary and nonboundary lineage-specific enhancers.
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Eichenlaub T, Cohen SM, Herranz H. Cell Competition Drives the Formation of Metastatic Tumors in a Drosophila Model of Epithelial Tumor Formation. Curr Biol 2016; 26:419-27. [PMID: 26853367 DOI: 10.1016/j.cub.2015.12.042] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 10/29/2015] [Accepted: 12/08/2015] [Indexed: 01/09/2023]
Abstract
Cell competition is a homeostatic process in which proliferating cells compete for survival. Elimination of otherwise normal healthy cells through competition is important during development and has recently been shown to contribute to maintaining tissue health during organismal aging. The mechanisms that allow for ongoing cell competition during adult life could, in principle, contribute to tumorigenesis. However, direct evidence supporting this hypothesis has been lacking. Here, we provide evidence that cell competition drives tumor formation in a Drosophila model of epithelial cancer. Cells expressing EGFR together with the conserved microRNA miR-8 acquire the properties of supercompetitors. Neoplastic transformation and metastasis depend on the ability of these cells to induce apoptosis and engulf nearby cells. miR-8 expression causes genome instability by downregulating expression of the Septin family protein Peanut. Cytokinesis failure due to downregulation of Peanut is required for tumorigenesis. This study provides evidence that the cellular mechanisms that drive cell competition during normal tissue growth can be co-opted to drive tumor formation and metastasis. Analogous mechanisms for cytokinesis failure may lead to polyploid intermediates in tumorigenesis in mammalian cancer models.
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Affiliation(s)
- Teresa Eichenlaub
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200 N, Denmark
| | - Stephen M Cohen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200 N, Denmark; Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673, Singapore.
| | - Héctor Herranz
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200 N, Denmark.
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Clark-Hachtel CM, Tomoyasu Y. Exploring the origin of insect wings from an evo-devo perspective. CURRENT OPINION IN INSECT SCIENCE 2016; 13:77-85. [PMID: 27436556 DOI: 10.1016/j.cois.2015.12.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/16/2015] [Accepted: 12/21/2015] [Indexed: 06/06/2023]
Abstract
Although insect wings are often used as an example of morphological novelty, the origin of insect wings remains a mystery and is regarded as a major conundrum in biology. Over a century of debates and observations have culminated in two prominent hypotheses on the origin of insect wings: the tergal hypothesis and the pleural hypothesis. However, despite accumulating efforts to unveil the origin of insect wings, neither hypothesis has been able to surpass the other. Recent investigations using the evolutionary developmental biology (evo-devo) approach have started shedding new light on this century-long debate. Here, we review these evo-devo studies and discuss how their findings may support a dual origin of insect wings, which could unify the two major hypotheses.
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Affiliation(s)
| | - Yoshinori Tomoyasu
- Miami University, Pearson Hall, 700E High Street, Oxford, OH 45056, USA.
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46
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Chi and dLMO function antagonistically on Notch signaling through directly regulation of fng transcription. Sci Rep 2016; 6:18937. [PMID: 26738424 PMCID: PMC4704065 DOI: 10.1038/srep18937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/01/2015] [Indexed: 11/08/2022] Open
Abstract
Gene apterous (ap), chip (chi) and beadex (bx) play important roles in the dorsal-ventral compartmentalization in Drosophila wing discs. Meanwhile, Notch signaling is essential to the same process. It has been reported that Ap and Chi function as a tetramer to regulate Notch signaling. At the same time, dLMO (the protein product of gene bx) regulates the activity of Ap by competing its binding with Chi. However, the detailed functions of Chi and dLMO on Notch signaling and the relevant mechanisms remain largely unknown. Here, we report the detailed functions of Chi and dLMO on Notch signaling. Different Chi protein levels in adjacent cells could activate Notch signaling mainly in the cells with higher level of Chi. dLMO could induce antagonistical phenotypes on Notch signaling compared to that induced by Chi. These processes depend on their direct regulation of fringe (fng) transcription.
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47
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Berndt AJE, Tang JCY, Ridyard MS, Lian T, Keatings K, Allan DW. Gene Regulatory Mechanisms Underlying the Spatial and Temporal Regulation of Target-Dependent Gene Expression in Drosophila Neurons. PLoS Genet 2015; 11:e1005754. [PMID: 26713626 PMCID: PMC4694770 DOI: 10.1371/journal.pgen.1005754] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 11/30/2015] [Indexed: 11/18/2022] Open
Abstract
Neuronal differentiation often requires target-derived signals from the cells they innervate. These signals typically activate neural subtype-specific genes, but the gene regulatory mechanisms remain largely unknown. Highly restricted expression of the FMRFa neuropeptide in Drosophila Tv4 neurons requires target-derived BMP signaling and a transcription factor code that includes Apterous. Using integrase transgenesis of enhancer reporters, we functionally dissected the Tv4-enhancer of FMRFa within its native cellular context. We identified two essential but discrete cis-elements, a BMP-response element (BMP-RE) that binds BMP-activated pMad, and a homeodomain-response element (HD-RE) that binds Apterous. These cis-elements have low activity and must be combined for Tv4-enhancer activity. Such combinatorial activity is often a mechanism for restricting expression to the intersection of cis-element spatiotemporal activities. However, concatemers of the HD-RE and BMP-RE cis-elements were found to independently generate the same spatiotemporal expression as the Tv4-enhancer. Thus, the Tv4-enhancer atypically combines two low-activity cis-elements that confer the same output from distinct inputs. The activation of target-dependent genes is assumed to 'wait' for target contact. We tested this directly, and unexpectedly found that premature BMP activity could not induce early FMRFa expression; also, we show that the BMP-insensitive HD-RE cis-element is activated at the time of target contact. This led us to uncover a role for the nuclear receptor, seven up (svp), as a repressor of FMRFa induction prior to target contact. Svp is normally downregulated immediately prior to target contact, and we found that maintaining Svp expression prevents cis-element activation, whereas reducing svp gene dosage prematurely activates cis-element activity. We conclude that the target-dependent FMRFa gene is repressed prior to target contact, and that target-derived BMP signaling directly activates FMRFa gene expression through an atypical gene regulatory mechanism.
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Affiliation(s)
- Anthony J. E. Berndt
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jonathan C. Y. Tang
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States America
| | - Marc S. Ridyard
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Tianshun Lian
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kathleen Keatings
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Douglas W. Allan
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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48
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Rao PR, Lin L, Huang H, Guha A, Roy S, Kornberg TB. Developmental compartments in the larval trachea of Drosophila. eLife 2015; 4. [PMID: 26491942 PMCID: PMC4718809 DOI: 10.7554/elife.08666] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 10/21/2015] [Indexed: 12/14/2022] Open
Abstract
The Drosophila tracheal system is a branched tubular network that forms in the embryo by a post-mitotic program of morphogenesis. In third instar larvae (L3), cells constituting the second tracheal metamere (Tr2) reenter the cell cycle. Clonal analysis of L3 Tr2 revealed that dividing cells in the dorsal trunk, dorsal branch and transverse connective branches respect lineage restriction boundaries near branch junctions. These boundaries corresponded to domains of gene expression, for example where cells expressing Spalt, Delta and Serrate in the dorsal trunk meet vein–expressing cells in the dorsal branch or transverse connective. Notch signaling was activated to one side of these borders and was required for the identity, specializations and segregation of border cells. These findings suggest that Tr2 is comprised of developmental compartments and that developmental compartments are an organizational feature relevant to branched tubular networks. DOI:http://dx.doi.org/10.7554/eLife.08666.001 As a fruit fly develops, its cells may sort themselves into groups according to the type of cell that they will eventually become. Some groups form ‘developmental compartments’ that are separated by boundaries that cells cannot move across. All the descendants of a cell in a compartment will activate the same specific gene (called a ‘selector’ gene) that determines their identity and fate. Similar compartments also form in the developing hindbrains of mammals, but it is not clear how general this mechanism of tissue patterning is. Fruit fly larvae undergo a physical transformation called metamorphosis to become adult fruit flies. Here, Rao et al. discover that the cells in the developing airways (or trachea) of the larvae at the start of metamorphosis are organised into compartments. At this stage the cells in the trachea start to divide and grow to make the adult tracheal system. The experiments show that these cells do not spread from one main branch of the tracheal system into another. Instead, the cells cluster in locations where the different branches meet on either side of a straight boundary. The cells on each side of these boundaries activate different genes that regulate their identity and development. For example, cells in one branch of the system switch on a selector gene that makes a protein called Spalt. A pathway known as Notch signaling is activated by cells on the other side of a nearby boundary in a different branch of the tracheal system. This separation of Spalt production and Notch activation establishes a cell communication system that keeps the cells of the different compartments apart. Rao et al.’s findings reveal a role for the Notch protein in regulating the organization of cells into compartments to form branches in fruit fly airways. A future challenge is to find out if Notch plays a similar role in other branched tissues, such as blood vessels. DOI:http://dx.doi.org/10.7554/eLife.08666.002
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Affiliation(s)
- Prashanth R Rao
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Li Lin
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Hai Huang
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Arjun Guha
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Sougata Roy
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Thomas B Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
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Establishment of a Developmental Compartment Requires Interactions between Three Synergistic Cis-regulatory Modules. PLoS Genet 2015; 11:e1005376. [PMID: 26468882 PMCID: PMC4607503 DOI: 10.1371/journal.pgen.1005376] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/19/2015] [Indexed: 12/28/2022] Open
Abstract
The subdivision of cell populations in compartments is a key event during animal development. In Drosophila, the gene apterous (ap) divides the wing imaginal disc in dorsal vs ventral cell lineages and is required for wing formation. ap function as a dorsal selector gene has been extensively studied. However, the regulation of its expression during wing development is poorly understood. In this study, we analyzed ap transcriptional regulation at the endogenous locus and identified three cis-regulatory modules (CRMs) essential for wing development. Only when the three CRMs are combined, robust ap expression is obtained. In addition, we genetically and molecularly analyzed the trans-factors that regulate these CRMs. Our results propose a three-step mechanism for the cell lineage compartment expression of ap that includes initial activation, positive autoregulation and Trithorax-mediated maintenance through separable CRMs. The separation of cell populations into distinct functional units is essential for both vertebrate and invertebrate animal development. A classical paradigm for this phenomenon is the establishment of developmental compartments during Drosophila wing development. These compartments depend on the restricted expression of two selector genes, engrailed in the posterior compartment and apterous (ap) in the dorsal compartment. Yet, despite the central role these genes and their restricted expression patterns play in Drosophila development, we still do not understand how these patterns are established or maintained. Here, by dissecting the regulatory sequences required for ap expression, we solve this problem for this critical selector gene. We used a combination of experimental approaches to identify and functionally characterize the cis-regulatory modules (CRMs) that regulate ap expression during Drosophila wing development. For these analyses we implement a novel technique allowing us to study the function of these CRMs in vivo, at the native ap locus. We found three ap CRMs crucial for wing development: the Early (apE) and the D/V (apDV) enhancers and the ap PRE (apP). Only when all three regulatory elements are combined is a uniform and complete ap expression domain generated. In summary, our results indicate that ap is regulated in time and space by a three-step mechanism that generates a lineage compartment by integrating input from separate CRMs for the initiation, refinement and maintenance of its expression.
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50
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Zhou C, Yang G, Chen M, He L, Xiang L, Ricupero C, Mao JJ, Ling J. Lhx6 and Lhx8: cell fate regulators and beyond. FASEB J 2015; 29:4083-91. [PMID: 26148970 PMCID: PMC4566936 DOI: 10.1096/fj.14-267500] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 06/22/2015] [Indexed: 12/11/2022]
Abstract
As transcription factors of the lines (LIN)-11/Islet (Isl)-1/mitosis entry checkpoint (MEC)-3 (LIM)-homeobox subfamily, LIM homeobox (Lhx)6 and -8 are remarkably conserved and involved in the morphogenesis of multiple organ systems. Lhx6 and -8 play overlapping and distinctive roles, but in general act as cell fate mediators and in turn are regulated by several transcriptional factors, such as sonic hedgehog, fibroblast growth factors, and wingless-int (Wnt)/β-catenin. In this review, we first summarize Lhx6 and -8 distributions in development and then explore how Lhx6 and -8 act as transcription factors and coregulators of cell lineage specification. Known Lhx6 and -8 functions and targets are outlined in neurogenesis, craniofacial development, and germ cell differentiation. The underlying mechanisms of Lhx6 and -8 in regulating cell fate remain elusive. Whether Lhx6 and -8 affect functions in tissues and organs other than neural, craniofacial, oocytes, and germ cells is largely unexplored. Taken together, Lhx6 and -8 are important regulators of cell lineage specification and may act as one of the pivotal mediators of stem cell fate. Undoubtedly, future investigations of Lhx6 and -8 biology will continue to yield fascinating insights into tissue development and homeostasis, in addition to their putative roles in tissue regeneration and ageing.
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Affiliation(s)
- Chen Zhou
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Guodong Yang
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Mo Chen
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Ling He
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Lusai Xiang
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Christopher Ricupero
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Jeremy J Mao
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Junqi Ling
- *Center for Craniofacial Regeneration, Columbia University Medical Center, New York, New York, USA; Guanghua School of Stomatology, Hospital of Stomatology, and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
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