1
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Poole RJ, Flames N, Cochella L. Neurogenesis in Caenorhabditis elegans. Genetics 2024; 228:iyae116. [PMID: 39167071 PMCID: PMC11457946 DOI: 10.1093/genetics/iyae116] [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: 05/28/2024] [Accepted: 06/24/2024] [Indexed: 08/23/2024] Open
Abstract
Animals rely on their nervous systems to process sensory inputs, integrate these with internal signals, and produce behavioral outputs. This is enabled by the highly specialized morphologies and functions of neurons. Neuronal cells share multiple structural and physiological features, but they also come in a large diversity of types or classes that give the nervous system its broad range of functions and plasticity. This diversity, first recognized over a century ago, spurred classification efforts based on morphology, function, and molecular criteria. Caenorhabditis elegans, with its precisely mapped nervous system at the anatomical level, an extensive molecular description of most of its neurons, and its genetic amenability, has been a prime model for understanding how neurons develop and diversify at a mechanistic level. Here, we review the gene regulatory mechanisms driving neurogenesis and the diversification of neuron classes and subclasses in C. elegans. We discuss our current understanding of the specification of neuronal progenitors and their differentiation in terms of the transcription factors involved and ensuing changes in gene expression and chromatin landscape. The central theme that has emerged is that the identity of a neuron is defined by modules of gene batteries that are under control of parallel yet interconnected regulatory mechanisms. We focus on how, to achieve these terminal identities, cells integrate information along their developmental lineages. Moreover, we discuss how neurons are diversified postembryonically in a time-, genetic sex-, and activity-dependent manner. Finally, we discuss how the understanding of neuronal development can provide insights into the evolution of neuronal diversity.
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Affiliation(s)
- Richard J Poole
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Nuria Flames
- Developmental Neurobiology Unit, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia 46012, Spain
| | - Luisa Cochella
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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2
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Kiontke KC, Herrera RA, Mason DA, Woronik A, Vernooy S, Patel Y, Fitch DHA. Tissue-specific RNA-seq defines genes governing male tail tip morphogenesis in C. elegans. Development 2024; 151:dev202787. [PMID: 39253748 PMCID: PMC11449441 DOI: 10.1242/dev.202787] [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: 02/13/2024] [Accepted: 08/21/2024] [Indexed: 09/11/2024]
Abstract
Caenorhabditis elegans males undergo sex-specific tail tip morphogenesis (TTM) under the control of the DM-domain transcription factor DMD-3. To find genes regulated by DMD-3, we performed RNA-seq of laser-dissected tail tips. We identified 564 genes differentially expressed (DE) in wild-type males versus dmd-3(-) males and hermaphrodites. The transcription profile of dmd-3(-) tail tips is similar to that in hermaphrodites. For validation, we analyzed transcriptional reporters for 49 genes and found male-specific or male-biased expression for 26 genes. Only 11 DE genes overlapped with genes found in a previous RNAi screen for defective TTM. GO enrichment analysis of DE genes finds upregulation of genes within the unfolded protein response pathway and downregulation of genes involved in cuticle maintenance. Of the DE genes, 40 are transcription factors, indicating that the gene network downstream of DMD-3 is complex and potentially modular. We propose modules of genes that act together in TTM and are co-regulated by DMD-3, among them the chondroitin synthesis pathway and the hypertonic stress response.
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Affiliation(s)
- Karin C. Kiontke
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | | | - D. Adam Mason
- Biology Department, Siena College, 515 Loudon Road, Loudonville, NY 12211, USA
| | - Alyssa Woronik
- Sacred Heart University, 5151 Park Avenue, Fairfield, CT 06825, USA
| | - Stephanie Vernooy
- Biology Department, Siena College, 515 Loudon Road, Loudonville, NY 12211, USA
| | - Yash Patel
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - David H. A. Fitch
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
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3
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Kiontke K, Fernandez P, Woronik A, Fitch DHA. Morphologically defined substages of tail morphogenesis in C. elegans males. Dev Dyn 2024. [PMID: 38924277 DOI: 10.1002/dvdy.721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 05/01/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Sex-specific morphogenesis occurs in Caenorhabditis elegans in the vulva of the hermaphrodite and in the male tail during the last larval stage. Temporal progression of vulva morphogenesis has been described in fine detail. However, a similar precise description of male tail morphogenesis was lacking. RESULTS We here describe morphogenesis of the male tail at time points matching vulva development with special focus on morphogenesis of the tail tip. Using fluorescent reporters, we follow changes in cell shapes, cell fusions, nuclear migration, modifications in the basement membrane, and formation of a new apical extracellular matrix at the end of the tail. CONCLUSION Our analysis answers two open questions about tail tip morphogenesis (TTM) by showing that one of the four tail tip cells, hyp11, remains largely separate, while the other cells fully fuse with each other and with two additional tail cells to form a ventral tail syncytium. This merger of cells begins at the apical surface early during TTM but is only completed toward the end of the process. This work provides a framework for future investigations of cell biological factors that drive male tail morphogenesis.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, New York, New York, USA
| | | | | | - David H A Fitch
- Department of Biology, New York University, New York, New York, USA
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4
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Wang C, Vidal B, Sural S, Loer C, Aguilar GR, Merritt DM, Toker IA, Vogt MC, Cros C, Hobert O. A neurotransmitter atlas of C. elegans males and hermaphrodites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.24.573258. [PMID: 38895397 PMCID: PMC11185579 DOI: 10.1101/2023.12.24.573258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Mapping neurotransmitter identities to neurons is key to understanding information flow in a nervous system. It also provides valuable entry points for studying the development and plasticity of neuronal identity features. In the C. elegans nervous system, neurotransmitter identities have been largely assigned by expression pattern analysis of neurotransmitter pathway genes that encode neurotransmitter biosynthetic enzymes or transporters. However, many of these assignments have relied on multicopy reporter transgenes that may lack relevant cis-regulatory information and therefore may not provide an accurate picture of neurotransmitter usage. We analyzed the expression patterns of 16 CRISPR/Cas9-engineered knock-in reporter strains for all main types of neurotransmitters in C. elegans (glutamate, acetylcholine, GABA, serotonin, dopamine, tyramine, and octopamine) in both the hermaphrodite and the male. Our analysis reveals novel sites of expression of these neurotransmitter systems within both neurons and glia, as well as non-neural cells. The resulting expression atlas defines neurons that may be exclusively neuropeptidergic, substantially expands the repertoire of neurons capable of co-transmitting multiple neurotransmitters, and identifies novel neurons that uptake monoaminergic neurotransmitters. Furthermore, we also observed unusual co-expression patterns of monoaminergic synthesis pathway genes, suggesting the existence of novel monoaminergic transmitters. Our analysis results in what constitutes the most extensive whole-animal-wide map of neurotransmitter usage to date, paving the way for a better understanding of neuronal communication and neuronal identity specification in C. elegans.
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Affiliation(s)
- Chen Wang
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Berta Vidal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Surojit Sural
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Curtis Loer
- Department of Biology, University of San Diego, San Diego, California, USA
| | - G. Robert Aguilar
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Daniel M. Merritt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Itai Antoine Toker
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Merly C. Vogt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Cyril Cros
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
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5
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Peedikayil-Kurien S, Setty H, Oren-Suissa M. Environmental experiences shape sexually dimorphic neuronal circuits and behaviour. FEBS J 2024; 291:1080-1101. [PMID: 36582142 DOI: 10.1111/febs.16714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 11/05/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022]
Abstract
Dimorphic traits, shaped by both natural and sexual selection, ensure optimal fitness and survival of the organism. This includes neuronal circuits that are largely affected by different experiences and environmental conditions. Recent evidence suggests that sexual dimorphism of neuronal circuits extends to different levels such as neuronal activity, connectivity and molecular topography that manifest in response to various experiences, including chemical exposures, starvation and stress. In this review, we propose some common principles that govern experience-dependent sexually dimorphic circuits in both vertebrate and invertebrate organisms. While sexually dimorphic neuronal circuits are predetermined, they have to maintain a certain level of fluidity to be adaptive to different experiences. The first layer of dimorphism is at the level of the neuronal circuit, which appears to be dictated by sex-biased transcription factors. This could subsequently lead to differences in the second layer of regulation namely connectivity and synaptic properties. The third regulator of experience-dependent responses is the receptor level, where dimorphic expression patterns determine the primary sensory encoding. We also highlight missing pieces in this field and propose future directions that can shed light onto novel aspects of sexual dimorphism with potential benefits to sex-specific therapeutic approaches. Thus, sexual identity and experience simultaneously determine behaviours that ultimately result in the maximal survival success.
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Affiliation(s)
| | - Hagar Setty
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Meital Oren-Suissa
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
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6
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Roggenbuck EC, Hall EA, Hanson IB, Roby AA, Zhang KK, Alkatib KA, Carter JA, Clewner JE, Gelfius AL, Gong S, Gordon FR, Iseler JN, Kotapati S, Li M, Maysun A, McCormick EO, Rastogi G, Sengupta S, Uzoma CU, Wolkov MA, Clowney EJ. Let's talk about sex: Mechanisms of neural sexual differentiation in Bilateria. WIREs Mech Dis 2024; 16:e1636. [PMID: 38185860 DOI: 10.1002/wsbm.1636] [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: 05/09/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 01/09/2024]
Abstract
In multicellular organisms, sexed gonads have evolved that facilitate release of sperm versus eggs, and bilaterian animals purposefully combine their gametes via mating behaviors. Distinct neural circuits have evolved that control these physically different mating events for animals producing eggs from ovaries versus sperm from testis. In this review, we will describe the developmental mechanisms that sexually differentiate neural circuits across three major clades of bilaterian animals-Ecdysozoa, Deuterosomia, and Lophotrochozoa. While many of the mechanisms inducing somatic and neuronal sex differentiation across these diverse organisms are clade-specific rather than evolutionarily conserved, we develop a common framework for considering the developmental logic of these events and the types of neuronal differences that produce sex-differentiated behaviors. This article is categorized under: Congenital Diseases > Stem Cells and Development Neurological Diseases > Stem Cells and Development.
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Affiliation(s)
- Emma C Roggenbuck
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Elijah A Hall
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Isabel B Hanson
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Alyssa A Roby
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Katherine K Zhang
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Kyle A Alkatib
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Joseph A Carter
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jarred E Clewner
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Anna L Gelfius
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Shiyuan Gong
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Finley R Gordon
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jolene N Iseler
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Samhita Kotapati
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Marilyn Li
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Areeba Maysun
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Elise O McCormick
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Geetanjali Rastogi
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Srijani Sengupta
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Chantal U Uzoma
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - Madison A Wolkov
- MCDB 464 - Cellular Diversity: Sex Differentiation of the Brain, University of Michigan, Ann Arbor, Michigan, USA
| | - E Josephine Clowney
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
- Michigan Neuroscience Institute Affiliate, University of Michigan, Ann Arbor, Michigan, USA
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7
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Kiontke K, Fernandez P, Woronik A, Fitch DHA. Morphologically defined substages of tail morphogenesis in C. elegans males. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.11.575265. [PMID: 38293029 PMCID: PMC10827050 DOI: 10.1101/2024.01.11.575265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Background Sex-specific morphogenesis occurs in C. elegans in the vulva of the hermaphrodite and in the male tail during the last larval stage. Temporal progression of vulva morphogenesis has been described in fine detail. However, a similar precise description of male tail morphogenesis was lacking. Results We here describe morphogenesis of the male tail at time points matching vulva development with special focus on morphogenesis of the tail tip. Using fluorescent reporters, we follow changes in cell shapes, cell fusions, nuclear migration, modifications in the basement membrane and formation of a new apical extracellular matrix at the end of the tail. Conclusion Our analysis answers two open questions about tail tip morphogenesis (TTM) by showing that one of the four tail tip cells, hyp11, remains separate while the other cells fuse with each other and with two additional tail cells to form a ventral tail syncytium. This fusion begins early during TTM but is only completed towards the end of the process. This work provides a framework for future investigations of cell-biological factors that drive male tail morphogenesis.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | - Porfirio Fernandez
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | - Alyssa Woronik
- Sacred Heart University, 5151 Park Avenue, Fairfield, CT 06825
| | - David H A Fitch
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
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8
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Kiontke K, Herrera RA, Mason DA, Woronik A, Vernooy S, Patel Y, Fitch DHA. Tissue-specific RNA-seq defines genes governing male tail tip morphogenesis in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575210. [PMID: 38260477 PMCID: PMC10802606 DOI: 10.1101/2024.01.12.575210] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Caenorhabditis elegans males undergo sex-specific tail tip morphogenesis (TTM) under the control of the transcription factor DMD-3. To find genes regulated by DMD-3, We performed RNA-seq of laser-dissected tail tips. We identified 564 genes differentially expressed (DE) in wild-type males vs. dmd-3(-) males and hermaphrodites. The transcription profile of dmd-3(-) tail tips is similar to that in hermaphrodites. For validation, we analyzed transcriptional reporters for 49 genes and found male-specific or male-biased expression for 26 genes. Only 11 DE genes overlapped with genes found in a previous RNAi screen for defective TTM. GO enrichment analysis of DE genes finds upregulation of genes within the UPR (unfolded protein response) pathway and downregulation of genes involved in cuticle maintenance. Of the DE genes, 40 are transcription factors, indicating that the gene network downstream of DMD-3 is complex and potentially modular. We propose modules of genes that act together in TTM and are coregulated by DMD-3, among them the chondroitin synthesis pathway and the hypertonic stress response.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | | | - D Adam Mason
- Biology Department, Siena College, 515 Loudon Road, Loudonville, NY 12211
| | - Alyssa Woronik
- Sacred Heart University, 5151 Park Avenue, Fairfield, CT 06825
| | - Stephanie Vernooy
- Biology Department, Siena College, 515 Loudon Road, Loudonville, NY 12211
| | - Yash Patel
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | - David H A Fitch
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
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9
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Zeng WX, Liu H, Hao Y, Qian KY, Tian FM, Li L, Yu B, Zeng XT, Gao S, Hu Z, Tong XJ. CaMKII mediates sexually dimorphic synaptic transmission at neuromuscular junctions in C. elegans. J Cell Biol 2023; 222:e202301117. [PMID: 37624117 PMCID: PMC10457463 DOI: 10.1083/jcb.202301117] [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: 01/27/2023] [Revised: 06/20/2023] [Accepted: 08/14/2023] [Indexed: 08/26/2023] Open
Abstract
Sexually dimorphic behaviors are ubiquitous throughout the animal kingdom. Although both sex-specific and sex-shared neurons have been functionally implicated in these diverse behaviors, less is known about the roles of sex-shared neurons. Here, we discovered sexually dimorphic cholinergic synaptic transmission in C. elegans occurring at neuromuscular junctions (NMJs), with males exhibiting increased release frequencies, which result in sexually dimorphic locomotion behaviors. Scanning electron microscopy revealed that males have significantly more synaptic vesicles (SVs) at their cholinergic synapses than hermaphrodites. Analysis of previously published transcriptome identified the male-enriched transcripts and focused our attention on UNC-43/CaMKII. We ultimately show that differential accumulation of UNC-43 at cholinergic neurons controls axonal SV abundance and synaptic transmission. Finally, we demonstrate that sex reversal of all neurons in hermaphrodites generates male-like cholinergic transmission and locomotion behaviors. Thus, beyond demonstrating UNC-43/CaMKII as an essential mediator of sex-specific synaptic transmission, our study provides molecular and cellular insights into how sex-shared neurons can generate sexually dimorphic locomotion behaviors.
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Affiliation(s)
- Wan-Xin Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Haowen Liu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
| | - Yue Hao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Kang-Ying Qian
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fu-Min Tian
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lei Li
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
| | - Bin Yu
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xian-Ting Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Shangbang Gao
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Zhitao Hu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, Australia
- Department of Neuroscience, City University of Hong Kong, Kowloon, China
| | - Xia-Jing Tong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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10
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Portman DS, Díaz-Balzac CA. Developmental biology: A hole in the matrix. Curr Biol 2023; 33:R1016-R1018. [PMID: 37816322 DOI: 10.1016/j.cub.2023.08.082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Neurons must access the environment to gather information, but this exposure must be carefully managed. New work finds that glial cells, the non-neuronal component of the nervous system, control environmental access by stage- and sex-specific patterning of the extracellular matrix.
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Affiliation(s)
- Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Biology, University of Rochester, 402 Hutchison Hall, Rochester, NY 14627, USA.
| | - Carlos A Díaz-Balzac
- Department of Biomedical Genetics, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA; Department of Medicine, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
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11
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Salzberg Y, Haque R, Oren-Suissa M. The synaptic basis for sexual dimorphism in the invertebrate nervous system. Curr Opin Neurobiol 2023; 82:102757. [PMID: 37572555 PMCID: PMC10506627 DOI: 10.1016/j.conb.2023.102757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/10/2023] [Accepted: 07/17/2023] [Indexed: 08/14/2023]
Abstract
Many animal behaviors are manifested differently in the two sexes of a given species, but how such sexual dimorphism is imprinted in the nervous system is not always clear. One mechanism involved is synaptic dimorphism, by which the same neurons exist in the two sexes, but form synapses that differ in features such as anatomy, molecular content or fate. While some evidence for synaptic dimorphism exists in humans and mammals, identifying these mechanisms in invertebrates has proven simpler, due to their smaller nervous systems and absence of external regulation by sex hormones. This review aims to present the current status of the field in invertebrates, the available toolkit for the study of synaptic dimorphism, and the standing questions that still remain incompletely answered.
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Affiliation(s)
- Yehuda Salzberg
- Department of Brain Science, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Rizwanul Haque
- Department of Brain Science, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Meital Oren-Suissa
- Department of Brain Science, Weizmann Institute of Science, Rehovot, 7610001, Israel.
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12
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Sun H, Hobert O. Temporal transitions in the postembryonic nervous system of the nematode Caenorhabditis elegans: Recent insights and open questions. Semin Cell Dev Biol 2023; 142:67-80. [PMID: 35688774 DOI: 10.1016/j.semcdb.2022.05.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/27/2022] [Accepted: 05/27/2022] [Indexed: 10/18/2022]
Abstract
After the generation, differentiation and integration into functional circuitry, post-mitotic neurons continue to change certain phenotypic properties throughout postnatal juvenile stages until an animal has reached a fully mature state in adulthood. We will discuss such changes in the context of the nervous system of the nematode C. elegans, focusing on recent descriptions of anatomical and molecular changes that accompany postembryonic maturation of neurons. We summarize the characterization of genetic timer mechanisms that control these temporal transitions or maturational changes, and discuss that many but not all of these transitions relate to sexual maturation of the animal. We describe how temporal, spatial and sex-determination pathways are intertwined to sculpt the emergence of cell-type specific maturation events. Finally, we lay out several unresolved questions that should be addressed to move the field forward, both in C. elegans and in vertebrates.
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Affiliation(s)
- Haosheng Sun
- Department of Cell, Developmental, and Integrative Biology. University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, New York, USA
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13
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Godini R, Pocock R. Characterization of the Doublesex/MAB-3 transcription factor DMD-9 in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2023; 13:jkac305. [PMID: 36454093 PMCID: PMC9911054 DOI: 10.1093/g3journal/jkac305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 09/30/2022] [Accepted: 11/10/2022] [Indexed: 12/05/2022]
Abstract
DMD-9 is a Caenorhabditis elegans Doublesex/MAB-3 Domain transcription factor (TF) of unknown function. Single-cell transcriptomics has revealed that dmd-9 is highly expressed in specific head sensory neurons, with lower levels detected in non-neuronal tissues (uterine cells and sperm). Here, we characterized endogenous dmd-9 expression and function in hermaphrodites and males to identify potential sexually dimorphic roles. In addition, we dissected the trans- and cis-regulatory mechanisms that control DMD-9 expression in neurons. Our results show that of the 22 neuronal cell fate reporters we assessed in DMD-9-expressing neurons, only the neuropeptide-encoding flp-19 gene is cell-autonomously regulated by DMD-9. Further, we did not identify defects in behaviors mediated by DMD-9 expressing neurons in dmd-9 mutants. We found that dmd-9 expression in neurons is regulated by 4 neuronal fate regulatory TFs: ETS-5, EGL-13, CHE-1, and TTX-1. In conclusion, our study characterized the DMD-9 expression pattern and regulatory logic for its control. The lack of detectable phenotypes in dmd-9 mutant animals suggests that other proteins compensate for its loss.
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Affiliation(s)
- Rasoul Godini
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Roger Pocock
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
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14
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Sexually dimorphic architecture and function of a mechanosensory circuit in C. elegans. Nat Commun 2022; 13:6825. [PMID: 36369281 PMCID: PMC9652301 DOI: 10.1038/s41467-022-34661-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 11/01/2022] [Indexed: 11/13/2022] Open
Abstract
How sensory perception is processed by the two sexes of an organism is still only partially understood. Despite some evidence for sexual dimorphism in auditory and olfactory perception, whether touch is sensed in a dimorphic manner has not been addressed. Here we find that the neuronal circuit for tail mechanosensation in C. elegans is wired differently in the two sexes and employs a different combination of sex-shared sensory neurons and interneurons in each sex. Reverse genetic screens uncovered cell- and sex-specific functions of the alpha-tubulin mec-12 and the sodium channel tmc-1 in sensory neurons, and of the glutamate receptors nmr-1 and glr-1 in interneurons, revealing the underlying molecular mechanisms that mediate tail mechanosensation. Moreover, we show that only in males, the sex-shared interneuron AVG is strongly activated by tail mechanical stimulation, and accordingly is crucial for their behavioral response. Importantly, sex reversal experiments demonstrate that the sexual identity of AVG determines both the behavioral output of the mechanosensory response and the molecular pathways controlling it. Our results present extensive sexual dimorphism in a mechanosensory circuit at both the cellular and molecular levels.
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15
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Brugman KI, Susoy V, Whittaker AJ, Palma W, Nava S, Samuel ADT, Sternberg PW. PEZO-1 and TRP-4 mechanosensors are involved in mating behavior in Caenorhabditis elegans. PNAS NEXUS 2022; 1:pgac213. [PMID: 36712331 PMCID: PMC9802279 DOI: 10.1093/pnasnexus/pgac213] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 09/22/2022] [Indexed: 02/01/2023]
Abstract
Male mating in Caenorhabditis elegans is a complex behavior with a strong mechanosensory component. C. elegans has several characterized mechanotransducer proteins, but few have been shown to contribute to mating. Here, we investigated the roles of PEZO-1, a piezo channel, and TRP-4, a mechanotransducing TRPN channel, in male mating behavior. We show that pezo-1 is expressed in several male-specific neurons with known roles in mating. We show that, among other neurons, trp-4 is expressed in the Post-Cloacal sensilla neuron type A (PCA) sensory neuron, which monitors relative sliding between the male and the hermaphrodite and inhibits neurons involved in vulva detection. Mutations in both genes compromise many steps of mating, including initial response to the hermaphrodite, scanning, turning, and vulva detection. We performed pan-neuronal imaging during mating between freely moving mutant males and hermaphrodites. Both pezo-1 and trp-4 mutants showed spurious activation of the sensory neurons involved in vulva detection. In trp-4 mutants, this spurious activation might be caused by PCA failure to inhibit vulva-detecting neurons during scanning. Indeed, we show that without functional TRP-4, PCA fails to detect the relative sliding between the male and hermaphrodite. Cell-specific TRP-4 expression restores PCA's mechanosensory function. Our results demonstrate new roles for both PEZO-1 and TRP-4 mechanotransducers in C. elegans mating behavior.
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Affiliation(s)
- Katherine I Brugman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Vladislav Susoy
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Allyson J Whittaker
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Wilber Palma
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Stephanie Nava
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Aravinthan D T Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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16
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Pechuk V, Goldman G, Salzberg Y, Chaubey AH, Bola RA, Hoffman JR, Endreson ML, Miller RM, Reger NJ, Portman DS, Ferkey DM, Schneidman E, Oren-Suissa M. Reprogramming the topology of the nociceptive circuit in C. elegans reshapes sexual behavior. Curr Biol 2022; 32:4372-4385.e7. [PMID: 36075218 DOI: 10.1016/j.cub.2022.08.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 06/28/2022] [Accepted: 08/15/2022] [Indexed: 10/14/2022]
Abstract
The effect of the detailed connectivity of a neural circuit on its function and the resulting behavior of the organism is a key question in many neural systems. Here, we study the circuit for nociception in C. elegans, which is composed of the same neurons in the two sexes that are wired differently. We show that the nociceptive sensory neurons respond similarly in the two sexes, yet the animals display sexually dimorphic behaviors to the same aversive stimuli. To uncover the role of the downstream network topology in shaping behavior, we learn and simulate network models that replicate the observed dimorphic behaviors and use them to predict simple network rewirings that would switch behavior between the sexes. We then show experimentally that these subtle synaptic rewirings indeed flip behavior. Interestingly, when presented with aversive cues, rewired males were compromised in finding mating partners, suggesting that network topologies that enable efficient avoidance of noxious cues have a reproductive "cost." Our results present a deconstruction of the design of a neural circuit that controls sexual behavior and how to reprogram it.
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Affiliation(s)
- Vladyslava Pechuk
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gal Goldman
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yehuda Salzberg
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Aditi H Chaubey
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - R Aaron Bola
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Jonathon R Hoffman
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Morgan L Endreson
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Renee M Miller
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, USA
| | - Noah J Reger
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA
| | - Denise M Ferkey
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Elad Schneidman
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Meital Oren-Suissa
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
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17
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Godini R, Fallahi H, Pocock R. The regulatory landscape of neurite development in Caenorhabditis elegans. Front Mol Neurosci 2022; 15:974208. [PMID: 36090252 PMCID: PMC9453034 DOI: 10.3389/fnmol.2022.974208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/26/2022] [Indexed: 11/18/2022] Open
Abstract
Neuronal communication requires precise connectivity of neurite projections (axons and dendrites). Developing neurites express cell-surface receptors that interpret extracellular cues to enable correct guidance toward, and connection with, target cells. Spatiotemporal regulation of neurite guidance molecule expression by transcription factors (TFs) is critical for nervous system development and function. Here, we review how neurite development is regulated by TFs in the Caenorhabditis elegans nervous system. By collecting publicly available transcriptome and ChIP-sequencing data, we reveal gene expression dynamics during neurite development, providing insight into transcriptional mechanisms governing construction of the nervous system architecture.
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Affiliation(s)
- Rasoul Godini
- Development and Stem Cells Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- *Correspondence: Rasoul Godini,
| | - Hossein Fallahi
- Department of Biology, School of Sciences, Razi University, Kermanshah, Iran
| | - Roger Pocock
- Development and Stem Cells Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Roger Pocock,
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18
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Casado-Navarro R, Serrano-Saiz E. DMRT Transcription Factors in the Control of Nervous System Sexual Differentiation. Front Neuroanat 2022; 16:937596. [PMID: 35958734 PMCID: PMC9361473 DOI: 10.3389/fnana.2022.937596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/15/2022] [Indexed: 11/13/2022] Open
Abstract
Sexual phenotypic differences in the nervous system are one of the most prevalent features across the animal kingdom. The molecular mechanisms responsible for sexual dimorphism throughout metazoan nervous systems are extremely diverse, ranging from intrinsic cell autonomous mechanisms to gonad-dependent endocrine control of sexual traits, or even extrinsic environmental cues. In recent years, the DMRT ancient family of transcription factors has emerged as being central in the development of sex-specific differentiation in all animals in which they have been studied. In this review, we provide an overview of the function of Dmrt genes in nervous system sexual regulation from an evolutionary perspective.
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19
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Pandey P, Kaur G, Babu K. Crosstalk between neurons and glia through G-protein coupled receptors: Insights from Caenorhabditis elegans. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 193:119-144. [PMID: 36357074 DOI: 10.1016/bs.pmbts.2022.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The past decades have witnessed a dogmatic shift from glia as supporting cells in the nervous system to their active roles in neurocentric functions. Neurons and glia communicate and show bidirectional responses through tripartite synapses. Studies across species indicate that neurotransmitters released by neurons are perceived by glial receptors, which allow for gliotransmitter release. These gliotransmitters can result in activation of neurons via neuronal GPCR receptors. However, studies of these molecular interactions are in their infancy. Caenorhabditis elegans has a conserved neuron-glia architectural repertoire with molecular and functional resemblance to mammals. Further, glia in C. elegans can be manipulated through ablation and mutations allowing for deciphering of glial dependent processes in vivo at single glial resolutions. Here, we will review recent findings from vertebrate and invertebrate organisms with a focus on how C. elegans can be used to advance our understanding of neuron-glia interactions through GPCRs.
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Affiliation(s)
- Pratima Pandey
- Indian Institute of Science Education and Research, Mohali, Punjab, India.
| | - Gazaldeep Kaur
- National Agri-Food Biotechnology Institute, Mohali, Punjab, India
| | - Kavita Babu
- Indian Institute of Science, Bangalore, Karnataka, India.
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20
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Kim D, Kim B. Anatomical and Functional Differences in the Sex-Shared Neurons of the Nematode C. elegans. Front Neuroanat 2022; 16:906090. [PMID: 35601998 PMCID: PMC9121059 DOI: 10.3389/fnana.2022.906090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
Studies on sexual dimorphism in the structure and function of the nervous system have been pivotal to understanding sex differences in behavior. Such studies, especially on invertebrates, have shown the importance of neurons specific to one sex (sex-specific neurons) in shaping sexually dimorphic neural circuits. Nevertheless, recent studies using the nematode C. elegans have revealed that the common neurons that exist in both sexes (sex-shared neurons) also play significant roles in generating sex differences in the structure and function of neural circuits. Here, we review the anatomical and functional differences in the sex-shared neurons of C. elegans. These sexually dimorphic characteristics include morphological differences in neurite projection or branching patterns with substantial changes in synaptic connectivity, differences in synaptic connections without obvious structural changes, and functional modulation in neural circuits with no or minimal synaptic connectivity changes. We also cover underlying molecular mechanisms whereby these sex-shared neurons contribute to the establishment of sexually dimorphic circuits during development and function differently between the sexes.
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21
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Du E, Wang S, Luan YX, Zhou C, Li Z, Li N, Zhou S, Zhang T, Ma W, Cui Y, Yuan D, Ren C, Zhang J, Roth S, Li S. Convergent adaptation of ootheca formation as a reproductive strategy in Polyneoptera. Mol Biol Evol 2022; 39:6531981. [PMID: 35192709 PMCID: PMC8892946 DOI: 10.1093/molbev/msac042] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Insects have evolved numerous adaptations and colonized diverse terrestrial environments. Several polyneopterans, including dictyopterans (cockroaches and mantids) and locusts, have developed oothecae, but little is known about the molecular mechanism, physiological function, and evolutionary significance of ootheca formation. Here, we demonstrate that the cockroach asymmetric colleterial glands produce vitellogenins, proline-rich protein, and glycine-rich protein as major ootheca structural proteins (OSPs) that undergo sclerotization and melanization for ootheca formation through the cooperative protocatechuic acid pathway and dopachrome and dopaminechrome subpathway. Functionally, OSP sclerotization and melanization prevent eggs from losing water at warm and dry conditions, and thus effectively maintain embryo viability. Dictyopterans and locusts convergently evolved vitellogenins, apolipoprotein D, and laminins as OSPs, whereas within Dictyoptera, cockroaches and mantids independently developed glycine-rich protein and fibroins as OSPs. Highlighting the ecological-evolutionary importance, convergent ootheca formation represents a successful reproductive strategy in Polyneoptera that promoted the radiation and establishment of cockroaches, mantids, and locusts.
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Affiliation(s)
- Erxia Du
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.,Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, China
| | - Shuai Wang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yun-Xia Luan
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Caisheng Zhou
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Zhaoxin Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Na Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China.,Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, China
| | - Shutang Zhou
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, China
| | - Tingting Zhang
- Research Institute of Applied Biology, Shanxi University, Taiyuan, China.,Institute for Zoology, University of Cologne, Cologne, D-50674, Germany
| | - Wentao Ma
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yingying Cui
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Dongwei Yuan
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Chonghua Ren
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jianzhen Zhang
- Research Institute of Applied Biology, Shanxi University, Taiyuan, China
| | - Siegfried Roth
- Institute for Zoology, University of Cologne, Cologne, D-50674, Germany
| | - Sheng Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.,Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, China
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22
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Goodwin SF, Hobert O. Molecular Mechanisms of Sexually Dimorphic Nervous System Patterning in Flies and Worms. Annu Rev Cell Dev Biol 2021; 37:519-547. [PMID: 34613817 DOI: 10.1146/annurev-cellbio-120319-115237] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Male and female brains display anatomical and functional differences. Such differences are observed in species across the animal kingdom, including humans, but have been particularly well-studied in two classic animal model systems, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans. Here we summarize recent advances in understanding how the worm and fly brain acquire sexually dimorphic features during development. We highlight the advantages of each system, illustrating how the precise anatomical delineation of sexual dimorphisms in worms has enabled recent analysis into how these dimorphisms become specified during development, and how focusing on sexually dimorphic neurons in the fly has enabled an increasingly detailed understanding of sex-specific behaviors.
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Affiliation(s)
- Stephen F Goodwin
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford OX1 3SR, United Kingdom;
| | - Oliver Hobert
- Department of Biological Sciences and Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA;
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23
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Susoy V, Hung W, Witvliet D, Whitener JE, Wu M, Park CF, Graham BJ, Zhen M, Venkatachalam V, Samuel ADT. Natural sensory context drives diverse brain-wide activity during C. elegans mating. Cell 2021; 184:5122-5137.e17. [PMID: 34534446 PMCID: PMC8488019 DOI: 10.1016/j.cell.2021.08.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 05/18/2021] [Accepted: 08/18/2021] [Indexed: 10/20/2022]
Abstract
Natural goal-directed behaviors often involve complex sequences of many stimulus-triggered components. Understanding how brain circuits organize such behaviors requires mapping the interactions between an animal, its environment, and its nervous system. Here, we use brain-wide neuronal imaging to study the full performance of mating by the C. elegans male. We show that as mating unfolds in a sequence of component behaviors, the brain operates similarly between instances of each component but distinctly between different components. When the full sensory and behavioral context is taken into account, unique roles emerge for each neuron. Functional correlations between neurons are not fixed but change with behavioral dynamics. From individual neurons to circuits, our study shows how diverse brain-wide dynamics emerge from the integration of sensory perception and motor actions in their natural context.
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Affiliation(s)
- Vladislav Susoy
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - Wesley Hung
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Daniel Witvliet
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Joshua E Whitener
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Min Wu
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Core Francisco Park
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Brett J Graham
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Vivek Venkatachalam
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Department of Physics, Northeastern University, Boston, MA 02115, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - Aravinthan D T Samuel
- Department of Physics, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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24
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Godini R, Handley A, Pocock R. Transcription Factors That Control Behavior-Lessons From C. elegans. Front Neurosci 2021; 15:745376. [PMID: 34646119 PMCID: PMC8503520 DOI: 10.3389/fnins.2021.745376] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/02/2021] [Indexed: 11/15/2022] Open
Abstract
Behavior encompasses the physical and chemical response to external and internal stimuli. Neurons, each with their own specific molecular identities, act in concert to perceive and relay these stimuli to drive behavior. Generating behavioral responses requires neurons that have the correct morphological, synaptic, and molecular identities. Transcription factors drive the specific gene expression patterns that define these identities, controlling almost every phenomenon in a cell from development to homeostasis. Therefore, transcription factors play an important role in generating and regulating behavior. Here, we describe the transcription factors, the pathways they regulate, and the neurons that drive chemosensation, mechanosensation, thermosensation, osmolarity sensing, complex, and sex-specific behaviors in the animal model Caenorhabditis elegans. We also discuss the current limitations in our knowledge, particularly our minimal understanding of how transcription factors contribute to the adaptive behavioral responses that are necessary for organismal survival.
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25
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Hobert O. Homeobox genes and the specification of neuronal identity. Nat Rev Neurosci 2021; 22:627-636. [PMID: 34446866 DOI: 10.1038/s41583-021-00497-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2021] [Indexed: 12/27/2022]
Abstract
The enormous diversity of cell types that characterizes any animal nervous system is defined by neuron-type-specific gene batteries that endow cells with distinct anatomical and functional properties. To understand how such cellular diversity is genetically specified, one needs to understand the gene regulatory programmes that control the expression of cell-type-specific gene batteries. The small nervous system of the nematode Caenorhabditis elegans has been comprehensively mapped at the cellular and molecular levels, which has enabled extensive, nervous system-wide explorations into whether there are common underlying mechanisms that specify neuronal cell-type diversity. One principle that emerged from these studies is that transcription factors termed 'terminal selectors' coordinate the expression of individual members of neuron-type-specific gene batteries, thereby assigning unique identities to individual neuron types. Systematic mutant analyses and recent nervous system-wide expression analyses have revealed that one transcription factor family, the homeobox gene family, is broadly used throughout the entire C. elegans nervous system to specify neuronal identity as terminal selectors. I propose that the preponderance of homeobox genes in neuronal identity control is a reflection of an evolutionary trajectory in which an ancestral neuron type was specified by one or more ancestral homeobox genes, and that this functional linkage then duplicated and diversified to generate distinct cell types in an evolving nervous system.
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Affiliation(s)
- Oliver Hobert
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY, USA.
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26
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The transcription factor LAG-1/CSL plays a Notch-independent role in controlling terminal differentiation, fate maintenance, and plasticity of serotonergic chemosensory neurons. PLoS Biol 2021; 19:e3001334. [PMID: 34232959 PMCID: PMC8289040 DOI: 10.1371/journal.pbio.3001334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 07/19/2021] [Accepted: 06/21/2021] [Indexed: 11/19/2022] Open
Abstract
During development, signal-regulated transcription factors (TFs) act as basal repressors and upon signalling through morphogens or cell-to-cell signalling shift to activators, mediating precise and transient responses. Conversely, at the final steps of neuron specification, terminal selector TFs directly initiate and maintain neuron-type specific gene expression through enduring functions as activators. C. elegans contains 3 types of serotonin synthesising neurons that share the expression of the serotonin biosynthesis pathway genes but not of other effector genes. Here, we find an unconventional role for LAG-1, the signal-regulated TF mediator of the Notch pathway, as terminal selector for the ADF serotonergic chemosensory neuron, but not for other serotonergic neuron types. Regulatory regions of ADF effector genes contain functional LAG-1 binding sites that mediate activation but not basal repression. lag-1 mutants show broad defects in ADF effector genes activation, and LAG-1 is required to maintain ADF cell fate and functions throughout life. Unexpectedly, contrary to reported basal repression state for LAG-1 prior to Notch receptor activation, gene expression activation in the ADF neuron by LAG-1 does not require Notch signalling, demonstrating a default activator state for LAG-1 independent of Notch. We hypothesise that the enduring activity of terminal selectors on target genes required uncoupling LAG-1 activating role from receiving the transient Notch signalling.
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27
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Nguyen I, Luth ES. DMD-10 is dispensable for the initial development of amphid sensory neurons and their survival in mature C. elegans. MICROPUBLICATION BIOLOGY 2021; 2021:10.17912/micropub.biology.000408. [PMID: 34142022 PMCID: PMC8204158 DOI: 10.17912/micropub.biology.000408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mechanosensory or chemosensory activation of glutamatergicASH amphid sensory neurons promotes avoidancebehaviors in C. elegans. Wormswith mutations in the transcription factor DMD-10 have impaired ASH-mediated sensorimotor reflexes. We hypothesized that the behavioral dysfunction in dmd-10 mutants could arise from impaired ASH development or survival leading to disrupted glutamatergic signaling.To test this, we performed in vivo fluorescence microscopy of young adult C. elegans amphid neurons after labeling with the lipophilic dye DiI. We quantified the number of ASH neurons as well as five other amphid sensory neuron pairs. We found that the number of amphid neurons in dmd-10 mutants was the same as in wild-type worms. Our results suggest that dmd-10 is not required for amphid neuron development or survival in mature C. elegans.
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Affiliation(s)
- Irene Nguyen
- Simmons University, Department of Biology, Boston, MA
| | - Eric S. Luth
- Simmons University, Department of Biology, Boston, MA,
Correspondence to: Eric S. Luth ()
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Lambert J, Lloret-Fernández C, Laplane L, Poole RJ, Jarriault S. On the origins and conceptual frameworks of natural plasticity-Lessons from single-cell models in C. elegans. Curr Top Dev Biol 2021; 144:111-159. [PMID: 33992151 DOI: 10.1016/bs.ctdb.2021.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
How flexible are cell identities? This problem has fascinated developmental biologists for several centuries and can be traced back to Abraham Trembley's pioneering manipulations of Hydra to test its regeneration abilities in the 1700s. Since the cell theory in the mid-19th century, developmental biology has been dominated by a single framework in which embryonic cells are committed to specific cell fates, progressively and irreversibly acquiring their differentiated identities. This hierarchical, unidirectional and irreversible view of cell identity has been challenged in the past decades through accumulative evidence that many cell types are more plastic than previously thought, even in intact organisms. The paradigm shift introduced by such plasticity calls into question several other key traditional concepts, such as how to define a differentiated cell or more generally cellular identity, and has brought new concepts, such as distinct cellular states. In this review, we want to contribute to this representation by attempting to clarify the conceptual and theoretical frameworks of cell plasticity and identity. In the context of these new frameworks we describe here an atlas of natural plasticity of cell identity in C. elegans, including our current understanding of the cellular and molecular mechanisms at play. The worm further provides interesting cases at the borderlines of cellular plasticity that highlight the conceptual challenges still ahead. We then discuss a set of future questions and perspectives arising from the studies of natural plasticity in the worm that are shared with other reprogramming and plasticity events across phyla.
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Affiliation(s)
- Julien Lambert
- IGBMC, Development and Stem Cells Department, CNRS UMR7104, INSERM U1258, Université de Strasbourg, Strasbourg, France
| | - Carla Lloret-Fernández
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Lucie Laplane
- CNRS UMR 8590, University Paris I Panthéon-Sorbonne, IHPST, Paris, France
| | - Richard J Poole
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.
| | - Sophie Jarriault
- IGBMC, Development and Stem Cells Department, CNRS UMR7104, INSERM U1258, Université de Strasbourg, Strasbourg, France.
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Serrano-Saiz E, Isogai Y. Single-cell molecular and developmental perspectives of sexually dimorphic circuits underlying innate social behaviors. Curr Opin Neurobiol 2021; 68:159-166. [PMID: 33915498 DOI: 10.1016/j.conb.2021.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 02/10/2021] [Accepted: 03/16/2021] [Indexed: 12/21/2022]
Abstract
While single-cell transcriptomics in the brain has uncovered a vast diversity of neural cell types in unprecedented detail, it is becoming increasingly urgent to address what exactly their functional roles are in the context of circuits and behavior. In this review, we discuss the molecular profiling of cell types in circuits underlying social behaviors in mice as a prominent case study. We first highlight key roles of molecularly identified sensory and downstream neurons involved in sexually dimorphic behaviors. We then propose future opportunities to define cell types using multimodal criteria, especially gene expression, physiology, as well as the developmental origin, to advance our understanding of these circuits.
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Affiliation(s)
| | - Yoh Isogai
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, London, United Kingdom.
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30
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Zhou H, Whitworth C, Pozmanter C, Neville MC, Van Doren M. Doublesex regulates fruitless expression to promote sexual dimorphism of the gonad stem cell niche. PLoS Genet 2021; 17:e1009468. [PMID: 33788836 PMCID: PMC8041189 DOI: 10.1371/journal.pgen.1009468] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 04/12/2021] [Accepted: 03/04/2021] [Indexed: 11/25/2022] Open
Abstract
Doublesex (Dsx) and Fruitless (Fru) are the two downstream transcription factors that actuate Drosophila sex determination. While Dsx assists Fru to regulate sex-specific behavior, whether Fru collaborates with Dsx in regulating other aspects of sexual dimorphism remains unknown. One important aspect of sexual dimorphism is found in the gonad stem cell (GSC) niches, where male and female GSCs are regulated to create large numbers of sperm and eggs. Here we report that Fru is expressed male-specifically in the GSC niche and plays important roles in the development and maintenance of these cells. Unlike previously-studied aspects of sex-specific Fru expression, which are regulated by Transformer (Tra)-mediated alternative splicing, we show that male-specific expression of fru in the gonad is regulated downstream of dsx, and is independent of tra. fru genetically interacts with dsx to support maintenance of the niche throughout development. Ectopic expression of fru inhibited female niche formation and partially masculinized the ovary. fru is also required autonomously for cyst stem cell maintenance and cyst cell survival. Finally, we identified a conserved Dsx binding site upstream of fru promoter P4 that regulates fru expression in the niche, indicating that fru is likely a direct target for transcriptional regulation by Dsx. These findings demonstrate that fru acts outside the nervous system to influence sexual dimorphism and reveal a new mechanism for regulating sex-specific expression of fru that is regulated at the transcriptional level by Dsx, rather than by alternative splicing by Tra.
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Affiliation(s)
- Hong Zhou
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, United States of America
| | - Cale Whitworth
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, United States of America
| | - Caitlin Pozmanter
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, United States of America
| | - Megan C. Neville
- Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford, United Kingdom
| | - Mark Van Doren
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, United States of America
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31
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Durbeck J, Breton C, Suter M, Luth ES, McGehee AM. The Doublesex/Mab-3 domain transcription factor DMD-10 regulates ASH-dependent behavioral responses. PeerJ 2021; 9:e10892. [PMID: 33665029 PMCID: PMC7916532 DOI: 10.7717/peerj.10892] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 01/12/2021] [Indexed: 12/28/2022] Open
Abstract
The Doublesex/Mab-3 Domain transcription factor DMD-10 is expressed in several cell types in C. elegans, including in the nervous system. We sought to investigate whether DMD-10 is required for normal neuronal function using behavioral assays. We found that mutation of dmd-10 did not broadly affect behavior. dmd-10 mutants were normal in several behavioral assays including a body bends assay for locomotion, egg laying, chemotaxis and response to gentle touch to the body. dmd-10 mutants did have defects in nose-touch responsiveness, which requires the glutamate receptor GLR-1. However, using quantitative fluorescence microscopy to measure levels of a GLR-1::GFP fusion protein in the ventral nerve cord, we found no evidence supporting a difference in the number of GLR-1 synapses or in the amount of GLR-1 present in dmd-10 mutants. dmd-10 mutants did have decreased responsiveness to high osmolarity, which, along with nose-touch, is sensed by the polymodal sensory neuron ASH. Furthermore, mutation of dmd-10 impaired behavioral response to optogenetic activation of ASH, suggesting that dmd-10 promotes neuronal signaling in ASH downstream of sensory receptor activation. Together our results suggest that DMD-10 is important in regulating the frequency of multiple ASH-dependent behavioral responses.
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Affiliation(s)
- Julia Durbeck
- Biology Department, Suffolk University, Boston, MA, USA
| | - Celine Breton
- Department of Biology, Simmons University, Boston, MA, USA
| | - Michael Suter
- Biology Department, Suffolk University, Boston, MA, USA
| | - Eric S Luth
- Department of Biology, Simmons University, Boston, MA, USA
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32
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Kasimatis KR, Sánchez-Ramírez S, Stevenson ZC. Sexual Dimorphism through the Lens of Genome Manipulation, Forward Genetics, and Spatiotemporal Sequencing. Genome Biol Evol 2021; 13:evaa243. [PMID: 33587127 PMCID: PMC7883666 DOI: 10.1093/gbe/evaa243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2020] [Indexed: 11/14/2022] Open
Abstract
Sexual reproduction often leads to selection that favors the evolution of sex-limited traits or sex-specific variation for shared traits. These sexual dimorphisms manifest due to sex-specific genetic architectures and sex-biased gene expression across development, yet the molecular mechanisms underlying these patterns are largely unknown. The first step is to understand how sexual dimorphisms arise across the genotype-phenotype-fitness map. The emergence of "4D genome technologies" allows for efficient, high-throughput, and cost-effective manipulation and observations of this process. Studies of sexual dimorphism will benefit from combining these technological advances (e.g., precision genome editing, inducible transgenic systems, and single-cell RNA sequencing) with clever experiments inspired by classic designs (e.g., bulked segregant analysis, experimental evolution, and pedigree tracing). This perspective poses a synthetic view of how manipulative approaches coupled with cutting-edge observational methods and evolutionary theory are poised to uncover the molecular genetic basis of sexual dimorphism with unprecedented resolution. We outline hypothesis-driven experimental paradigms for identifying genetic mechanisms of sexual dimorphism among tissues, across development, and over evolutionary time.
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Affiliation(s)
- Katja R Kasimatis
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario, USA
| | | | - Zachary C Stevenson
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, USA
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33
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Meeh KL, Rickel CT, Sansano AJ, Shirangi TR. The development of sex differences in the nervous system and behavior of flies, worms, and rodents. Dev Biol 2021; 472:75-84. [PMID: 33484707 DOI: 10.1016/j.ydbio.2021.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/12/2021] [Accepted: 01/15/2021] [Indexed: 01/14/2023]
Abstract
Understanding how sex differences in innate animal behaviors arise has long fascinated biologists. As a general rule, the potential for sex differences in behavior is built by the developmental actions of sex-specific hormones or regulatory proteins that direct the sexual differentiation of the nervous system. In the last decade, studies in several animal systems have uncovered neural circuit mechanisms underlying discrete sexually dimorphic behaviors. Moreover, how certain hormones and regulatory proteins implement the sexual differentiation of these neural circuits has been illuminated in tremendous detail. Here, we discuss some of these mechanisms with three case-studies-mate recognition in flies, maturation of mating behavior in worms, and play-fighting behavior in young rodents. These studies illustrate general and unique developmental mechanisms to establish sex differences in neuroanatomy and behavior and highlight future challenges for the field.
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Affiliation(s)
- Kristen L Meeh
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Clare T Rickel
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Alexander J Sansano
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Troy R Shirangi
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA.
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34
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Molina-García L, Lloret-Fernández C, Cook SJ, Kim B, Bonnington RC, Sammut M, O'Shea JM, Gilbert SPR, Elliott DJ, Hall DH, Emmons SW, Barrios A, Poole RJ. Direct glia-to-neuron transdifferentiation gives rise to a pair of male-specific neurons that ensure nimble male mating. eLife 2020; 9:e48361. [PMID: 33138916 PMCID: PMC7609048 DOI: 10.7554/elife.48361] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/02/2020] [Indexed: 12/20/2022] Open
Abstract
Sexually dimorphic behaviours require underlying differences in the nervous system between males and females. The extent to which nervous systems are sexually dimorphic and the cellular and molecular mechanisms that regulate these differences are only beginning to be understood. We reveal here a novel mechanism by which male-specific neurons are generated in Caenorhabditis elegans through the direct transdifferentiation of sex-shared glial cells. This glia-to-neuron cell fate switch occurs during male sexual maturation under the cell-autonomous control of the sex-determination pathway. We show that the neurons generated are cholinergic, peptidergic, and ciliated putative proprioceptors which integrate into male-specific circuits for copulation. These neurons ensure coordinated backward movement along the mate's body during mating. One step of the mating sequence regulated by these neurons is an alternative readjustment movement performed when intromission becomes difficult to achieve. Our findings reveal programmed transdifferentiation as a developmental mechanism underlying flexibility in innate behaviour.
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Affiliation(s)
- Laura Molina-García
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Carla Lloret-Fernández
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Steven J Cook
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineNew YorkUnited States
| | - Byunghyuk Kim
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Rachel C Bonnington
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Michele Sammut
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Jack M O'Shea
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Sophie PR Gilbert
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - David J Elliott
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - David H Hall
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Scott W Emmons
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineNew YorkUnited States
- Department of Genetics, Albert Einstein College of MedicineNew YorkUnited States
| | - Arantza Barrios
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Richard J Poole
- Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
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35
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Bayer EA, Stecky RC, Neal L, Katsamba PS, Ahlsen G, Balaji V, Hoppe T, Shapiro L, Oren-Suissa M, Hobert O. Ubiquitin-dependent regulation of a conserved DMRT protein controls sexually dimorphic synaptic connectivity and behavior. eLife 2020; 9:59614. [PMID: 33021200 PMCID: PMC7538159 DOI: 10.7554/elife.59614] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/05/2020] [Indexed: 12/20/2022] Open
Abstract
Sex-specific synaptic connectivity is beginning to emerge as a remarkable, but little explored feature of animal brains. We describe here a novel mechanism that promotes sexually dimorphic neuronal function and synaptic connectivity in the nervous system of the nematode Caenorhabditis elegans. We demonstrate that a phylogenetically conserved, but previously uncharacterized Doublesex/Mab-3 related transcription factor (DMRT), dmd-4, is expressed in two classes of sex-shared phasmid neurons specifically in hermaphrodites but not in males. We find dmd-4 to promote hermaphrodite-specific synaptic connectivity and neuronal function of phasmid sensory neurons. Sex-specificity of DMD-4 function is conferred by a novel mode of posttranslational regulation that involves sex-specific protein stabilization through ubiquitin binding to a phylogenetically conserved but previously unstudied protein domain, the DMA domain. A human DMRT homolog of DMD-4 is controlled in a similar manner, indicating that our findings may have implications for the control of sexual differentiation in other animals as well.
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Affiliation(s)
- Emily A Bayer
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Rebecca C Stecky
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Lauren Neal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Phinikoula S Katsamba
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Goran Ahlsen
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Vishnu Balaji
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
| | - Meital Oren-Suissa
- Weizmann Institute of Science, Department of Neurobiology, Rehovot, Israel
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States
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36
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Salzberg Y, Gat A, Oren-Suissa M. One template, two outcomes: How does the sex-shared nervous system generate sex-specific behaviors? Curr Top Dev Biol 2020; 144:245-268. [PMID: 33992155 DOI: 10.1016/bs.ctdb.2020.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sex-specific behaviors are common in nature and are crucial for reproductive fitness and species survival. A key question in the field of sex/gender neurobiology is whether and to what degree the sex-shared nervous system differs between the sexes in the anatomy, connectivity and molecular identity of its components. An equally intriguing issue is how does the same sex-shared neuronal template diverge to mediate distinct behavioral outputs in females and males. This chapter aims to present the most up-to-date understanding of how this task is achieved in C. elegans. The vast majority of neurons in C. elegans are shared among the two sexes in terms of their lineage history, anatomical position and neuronal identity. Yet a substantial amount of evidence points to the hermaphrodite-male counterparts of some neurons expressing different genes and forming different synaptic connections. This, in turn, enables the same cells and circuits to transmit discrete signals in the two sexes and ultimately execute different functions. We review the various sex-shared behavioral paradigms that have been shown to be sexually dimorphic in recent years, discuss the mechanisms that underlie these examples, refer to the developmental regulation of neuronal dimorphism and suggest evolutionary concepts that emerge from the data.
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Affiliation(s)
- Yehuda Salzberg
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Asaf Gat
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Meital Oren-Suissa
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
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37
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Jin H, Kim B. Neurite Branching Regulated by Neuronal Cell Surface Molecules in Caenorhabditis elegans. Front Neuroanat 2020; 14:59. [PMID: 32973467 PMCID: PMC7471659 DOI: 10.3389/fnana.2020.00059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/04/2020] [Indexed: 01/02/2023] Open
Abstract
The high synaptic density in the nervous system results from the ability of neurites to branch. Neuronal cell surface molecules play central roles during neurite branch formation. The underlying mechanisms of surface molecule activity have often been elucidated using invertebrates with simple nervous systems. Here, we review recent advances in understanding the molecular mechanisms of neurite branching in the nematode Caenorhabditis elegans. We discuss how cell surface receptor complexes link to and modulate actin dynamics to regulate dendritic and axonal branch formation. The mechanisms of neurite branching are often coupled with other neural circuit developmental processes, such as synapse formation and axon guidance, via the same cell-cell surface molecular interactions. We also cover ectopic and sex-specific neurite branching in C. elegans in an attempt to illustrate the importance of these studies in contributing to our understanding of conserved cell surface molecule regulation of neurite branch formation.
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Affiliation(s)
- HoYong Jin
- Department of Life Science, Dongguk University-Seoul, Goyang, South Korea
| | - Byunghyuk Kim
- Department of Life Science, Dongguk University-Seoul, Goyang, South Korea
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38
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Reilly MB, Cros C, Varol E, Yemini E, Hobert O. Unique homeobox codes delineate all the neuron classes of C. elegans. Nature 2020; 584:595-601. [PMID: 32814896 PMCID: PMC7587405 DOI: 10.1038/s41586-020-2618-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022]
Abstract
It is presently not known whether neuronal cell type diversity, defined by cell type-specific anatomical, biophysical, functional and molecular signatures, can be reduced to relatively simple molecular descriptors of neuronal identity 1. Examination of the expression of all conserved homeodomain proteins encoded by the Caenorhabditis elegans genome 2 reveals that the complete set of 118 C. elegans neuron classes can be described individually by unique combinations of homeodomain protein expression, thereby providing the simplest currently known descriptor of neuronal diversity. Computational as well as genetic loss of function analyses corroborate that homeodomain proteins not only provide unique descriptors of neuron type, but also play a critical role specifying neuronal identity. We speculate that the pervasive employment of homeobox genes in defining unique neuronal identities reflects the evolutionary history of neuronal cell-type specification.
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Affiliation(s)
- Molly B Reilly
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Cyril Cros
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Erdem Varol
- Department of Statistics, Columbia University, New York, NY, USA
| | - Eviatar Yemini
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA.
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39
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Modular Organization of Cis-regulatory Control Information of Neurotransmitter Pathway Genes in Caenorhabditis elegans. Genetics 2020; 215:665-681. [PMID: 32444379 DOI: 10.1534/genetics.120.303206] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/20/2020] [Indexed: 11/18/2022] Open
Abstract
We explore here the cis-regulatory logic that dictates gene expression in specific cell types in the nervous system. We focus on a set of eight genes involved in the synthesis, transport, and breakdown of three neurotransmitter systems: acetylcholine (unc-17 /VAChT, cha-1 /ChAT, cho-1 /ChT, and ace-2 /AChE), glutamate (eat-4 /VGluT), and γ-aminobutyric acid (unc-25 /GAD, unc-46 /LAMP, and unc-47 /VGAT). These genes are specifically expressed in defined subsets of cells in the nervous system. Through transgenic reporter gene assays, we find that the cellular specificity of expression of all of these genes is controlled in a modular manner through distinct cis-regulatory elements, corroborating the previously inferred piecemeal nature of specification of neurotransmitter identity. This modularity provides the mechanistic basis for the phenomenon of "phenotypic convergence," in which distinct regulatory pathways can generate similar phenotypic outcomes (i.e., the acquisition of a specific neurotransmitter identity) in different neuron classes. We also identify cases of enhancer pleiotropy, in which the same cis-regulatory element is utilized to control gene expression in distinct neuron types. We engineered a cis-regulatory allele of the vesicular acetylcholine transporter, unc-17 /VAChT, to assess the functional contribution of a "shadowed" enhancer. We observed a selective loss of unc-17 /VAChT expression in one cholinergic pharyngeal pacemaker motor neuron class and a behavioral phenotype that matches microsurgical removal of this neuron. Our analysis illustrates the value of understanding cis-regulatory information to manipulate gene expression and control animal behavior.
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40
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Leyva-Díaz E, Masoudi N, Serrano-Saiz E, Glenwinkel L, Hobert O. Brn3/POU-IV-type POU homeobox genes-Paradigmatic regulators of neuronal identity across phylogeny. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 9:e374. [PMID: 32012462 DOI: 10.1002/wdev.374] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 02/06/2023]
Abstract
One approach to understand the construction of complex systems is to investigate whether there are simple design principles that are commonly used in building such a system. In the context of nervous system development, one may ask whether the generation of its highly diverse sets of constituents, that is, distinct neuronal cell types, relies on genetic mechanisms that share specific common features. Specifically, are there common patterns in the function of regulatory genes across different neuron types and are those regulatory mechanisms not only used in different parts of one nervous system, but are they conserved across animal phylogeny? We address these questions here by focusing on one specific, highly conserved and well-studied regulatory factor, the POU homeodomain transcription factor UNC-86. Work over the last 30 years has revealed a common and paradigmatic theme of unc-86 function throughout most of the neuron types in which Caenorhabditis elegans unc-86 is expressed. Apart from its role in preventing lineage reiterations during development, UNC-86 operates in combination with distinct partner proteins to initiate and maintain terminal differentiation programs, by coregulating a vast array of functionally distinct identity determinants of specific neuron types. Mouse orthologs of unc-86, the Brn3 genes, have been shown to fulfill a similar function in initiating and maintaining neuronal identity in specific parts of the mouse brain and similar functions appear to be carried out by the sole Drosophila ortholog, Acj6. The terminal selector function of UNC-86 in many different neuron types provides a paradigm for neuronal identity regulation across phylogeny. This article is categorized under: Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms Invertebrate Organogenesis > Worms Nervous System Development > Vertebrates: Regional Development.
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Affiliation(s)
- Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Neda Masoudi
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | | | - Lori Glenwinkel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
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41
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Wexler J, Delaney EK, Belles X, Schal C, Wada-Katsumata A, Amicucci MJ, Kopp A. Hemimetabolous insects elucidate the origin of sexual development via alternative splicing. eLife 2019; 8:e47490. [PMID: 31478483 PMCID: PMC6721801 DOI: 10.7554/elife.47490] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 08/11/2019] [Indexed: 02/02/2023] Open
Abstract
Insects are the only known animals in which sexual differentiation is controlled by sex-specific splicing. The doublesex transcription factor produces distinct male and female isoforms, which are both essential for sex-specific development. dsx splicing depends on transformer, which is also alternatively spliced such that functional Tra is only present in females. This pathway has evolved from an ancestral mechanism where dsx was independent of tra and expressed and required only in males. To reconstruct this transition, we examined three basal, hemimetabolous insect orders: Hemiptera, Phthiraptera, and Blattodea. We show that tra and dsx have distinct functions in these insects, reflecting different stages in the changeover from a transcription-based to a splicing-based mode of sexual differentiation. We propose that the canonical insect tra-dsx pathway evolved via merger between expanding dsx function (from males to both sexes) and narrowing tra function (from a general splicing factor to dedicated regulator of dsx).
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Affiliation(s)
- Judith Wexler
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
| | - Emily Kay Delaney
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
| | - Xavier Belles
- Institut de Biologia EvolutivaConsejo Superior de Investigaciones Cientificas, Universitat Pompeu FabraBarcelonaSpain
| | - Coby Schal
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighUnited States
| | - Ayako Wada-Katsumata
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighUnited States
| | - Matthew J Amicucci
- Department of ChemistryUniversity of California, DavisDavisUnited States
| | - Artyom Kopp
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
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42
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Rice GR, Barmina O, Luecke D, Hu K, Arbeitman M, Kopp A. Modular tissue-specific regulation of doublesex underpins sexually dimorphic development in Drosophila. Development 2019; 146:dev178285. [PMID: 31285355 PMCID: PMC6679366 DOI: 10.1242/dev.178285] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
The ability of a single genome to produce distinct and often dramatically different male and female forms is one of the wonders of animal development. In Drosophila melanogaster, most sexually dimorphic traits are controlled by sex-specific isoforms of the doublesex (dsx) transcription factor, and dsx expression is mostly limited to cells that give rise to sexually dimorphic traits. However, it is unknown how this mosaic of sexually dimorphic and monomorphic organs arises. Here, we characterize the cis-regulatory sequences that control dsx expression in the foreleg, which contains multiple types of sex-specific sensory organs. We find that separate modular enhancers are responsible for dsx expression in each sexually dimorphic organ. Expression of dsx in the sex comb is co-regulated by two enhancers with distinct spatial and temporal specificities that are separated by a genitalia-specific enhancer. The sex comb-specific enhancer from D. willistoni, a species that primitively lacks sex combs, is not active in the foreleg. Thus, the mosaic of sexually dimorphic and monomorphic organs depends on modular regulation of dsx transcription by dedicated cell type-specific enhancers.
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Affiliation(s)
- Gavin R Rice
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Olga Barmina
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - David Luecke
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Kevin Hu
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Michelle Arbeitman
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Artyom Kopp
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
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43
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Lawson H, Vuong E, Miller RM, Kiontke K, Fitch DHA, Portman DS. The Makorin lep-2 and the lncRNA lep-5 regulate lin-28 to schedule sexual maturation of the C. elegans nervous system. eLife 2019; 8:e43660. [PMID: 31264582 PMCID: PMC6606027 DOI: 10.7554/elife.43660] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/10/2019] [Indexed: 12/30/2022] Open
Abstract
Sexual maturation must occur on a controlled developmental schedule. In mammals, Makorin3 (MKRN3) and the miRNA regulators LIN28A/B are key regulators of this process, but how they act is unclear. In C. elegans, sexual maturation of the nervous system includes the functional remodeling of postmitotic neurons and the onset of adult-specific behaviors. Here, we find that the lin-28-let-7 axis (the 'heterochronic pathway') determines the timing of these events. Upstream of lin-28, the Makorin lep-2 and the lncRNA lep-5 regulate maturation cell-autonomously, indicating that distributed clocks, not a central timer, coordinate sexual differentiation of the C. elegans nervous system. Overexpression of human MKRN3 delays aspects of C. elegans sexual maturation, suggesting the conservation of Makorin function. These studies reveal roles for a Makorin and a lncRNA in timing of sexual differentiation; moreover, they demonstrate deep conservation of the lin-28-let-7 system in controlling the functional maturation of the nervous system.
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Affiliation(s)
- Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Edward Vuong
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
| | - Renee M Miller
- Department of Brain and Cognitive SciencesUniversity of RochesterRochesterUnited States
| | - Karin Kiontke
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - David HA Fitch
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
- Department of NeuroscienceUniversity of RochesterRochesterUnited States
- DelMonte Institute for NeuroscienceUniversity of RochesterRochesterUnited States
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44
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Neuronal identity control by terminal selectors in worms, flies, and chordates. Curr Opin Neurobiol 2019; 56:97-105. [PMID: 30665084 DOI: 10.1016/j.conb.2018.12.006] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 12/10/2018] [Accepted: 12/15/2018] [Indexed: 11/21/2022]
Abstract
How do post-mitotic neurons acquire and maintain their terminal identity? Genetic mutant analysis in the nematode Caenorhabditis elegans has revealed common molecular programs that control neuronal identity. Neuron type-specific combinations of transcription factors, called terminal selectors, act as master regulatory factors to initiate and maintain terminal identity programs through direct regulation of neuron type-specific effector genes. We will provide here an update on recent studies that solidify the terminal selector concept in worms, flies and chordates. We will also describe how the terminal selector concept has been expanded by recent work in C. elegans to explain neuronal subtype diversification and plasticity of neuronal identity.
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45
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Pereira L, Aeschimann F, Wang C, Lawson H, Serrano-Saiz E, Portman DS, Großhans H, Hobert O. Timing mechanism of sexually dimorphic nervous system differentiation. eLife 2019; 8:e42078. [PMID: 30599092 PMCID: PMC6312707 DOI: 10.7554/elife.42078] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
The molecular mechanisms that control the timing of sexual differentiation in the brain are poorly understood. We found that the timing of sexually dimorphic differentiation of postmitotic, sex-shared neurons in the nervous system of the Caenorhabditis elegans male is controlled by the temporally regulated miRNA let-7 and its target lin-41, a translational regulator. lin-41 acts through lin-29a, an isoform of a conserved Zn finger transcription factor, expressed in a subset of sex-shared neurons only in the male. Ectopic lin-29a is sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron-type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional sex- and neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner.
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Affiliation(s)
- Laura Pereira
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Florian Aeschimann
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Chen Wang
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Esther Serrano-Saiz
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- DelMonte Institute for Neuroscience, Department of Biomedical GeneticsUniversity of RochesterNew YorkUnited States
| | - Helge Großhans
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
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46
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Knoedler JR, Shah NM. Molecular mechanisms underlying sexual differentiation of the nervous system. Curr Opin Neurobiol 2018; 53:192-197. [PMID: 30316066 DOI: 10.1016/j.conb.2018.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/18/2018] [Indexed: 10/28/2022]
Abstract
A long-standing goal in developmental neuroscience is to understand the mechanisms by which steroid sex hormones pattern the mammalian central nervous system along male or female pathways to enable subsequent displays of sexually dimorphic behaviors. In this article, we review recent advances in understanding the epigenetic and transcriptional mechanisms mediating sexual differentiation of the brain in mammals, flies, and worms. These studies suggest a model of sexual differentiation wherein master regulators of sex determination initiate a cascade of sexually dimorphic gene expression that controls development of neural pathways and behavioral displays in a strikingly modular manner. With these advances in molecular genetics, it is now feasible to disassemble different components of sexually dimorphic social behaviors without disrupting other behavioral interactions. Such experimental tractability promises rapid advances in this exciting field.
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Affiliation(s)
- Joseph R Knoedler
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, United States
| | - Nirao M Shah
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, United States; Department of Neurobiology, Stanford University, Stanford, CA 94305, United States.
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47
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Haag ES, Fitch DHA, Delattre M. From "the Worm" to "the Worms" and Back Again: The Evolutionary Developmental Biology of Nematodes. Genetics 2018; 210:397-433. [PMID: 30287515 PMCID: PMC6216592 DOI: 10.1534/genetics.118.300243] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 08/03/2018] [Indexed: 12/13/2022] Open
Abstract
Since the earliest days of research on nematodes, scientists have noted the developmental and morphological variation that exists within and between species. As various cellular and developmental processes were revealed through intense focus on Caenorhabditis elegans, these comparative studies have expanded. Within the genus Caenorhabditis, they include characterization of intraspecific polymorphisms and comparisons of distinct species, all generally amenable to the same laboratory culture methods and supported by robust genomic and experimental tools. The C. elegans paradigm has also motivated studies with more distantly related nematodes and animals. Combined with improved phylogenies, this work has led to important insights about the evolution of nematode development. First, while many aspects of C. elegans development are representative of Caenorhabditis, and of terrestrial nematodes more generally, others vary in ways both obvious and cryptic. Second, the system has revealed several clear examples of developmental flexibility in achieving a particular trait. This includes developmental system drift, in which the developmental control of homologous traits has diverged in different lineages, and cases of convergent evolution. Overall, the wealth of information and experimental techniques developed in C. elegans is being leveraged to make nematodes a powerful system for evolutionary cellular and developmental biology.
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Affiliation(s)
- Eric S Haag
- Department of Biology, University of Maryland, College Park, Maryland 20742
| | | | - Marie Delattre
- Laboratoire de Biologie Moléculaire de la Cellule, CNRS, INSERM, Ecole Normale Supérieure de Lyon, 69007, France
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48
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Serrano-Saiz E, Leyva-Díaz E, De La Cruz E, Hobert O. BRN3-type POU Homeobox Genes Maintain the Identity of Mature Postmitotic Neurons in Nematodes and Mice. Curr Biol 2018; 28:2813-2823.e2. [PMID: 30146154 DOI: 10.1016/j.cub.2018.06.045] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 06/08/2018] [Accepted: 06/19/2018] [Indexed: 11/28/2022]
Abstract
Many distinct regulatory factors have been shown to be required for the proper initiation of neuron-type-specific differentiation programs, but much less is known about the regulatory programs that maintain the differentiated state in the adult [1-3]. One possibility is that regulatory factors that initiate a terminal differentiation program during development are continuously required to maintain the differentiated state. Here, we test this hypothesis by investigating the function of two orthologous POU homeobox genes in nematodes and mice. The C. elegans POU homeobox gene unc-86 is a terminal selector that is required during development to initiate the terminal differentiation program of several distinct neuron classes [4-13]. Through post-developmental removal of unc-86 activity, we show here that unc-86 is also continuously required throughout the life of many neuron classes to maintain neuron-class-specific identity features. Similarly, the mouse unc-86 ortholog Brn3a/POU4F1 has been shown to control the initiation of the terminal differentiation program of distinct neuron types across the mouse brain, such as the medial habenular neurons [14-20]. By conditionally removing Brn3a in the adult mouse central nervous system, we show that, like its invertebrate ortholog unc-86, Brn3a is also required for the maintenance of terminal identity features of medial habenular neurons. In addition, Brn3a is required for the survival of these neurons, indicating that identity maintenance and survival are genetically linked. We conclude that the continuous expression of transcription factors is essential for the active maintenance of the differentiated state of a neuron across phylogeny.
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Affiliation(s)
- Esther Serrano-Saiz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA.
| | - Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Estanislao De La Cruz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY, USA.
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49
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Abstract
Sex differences in the brain are prominent features across the animal kingdom. Understanding the anatomical and regulatory mechanisms behind these differences is critical for both explaining sexually dimorphic behaviors and developing sex-targeted treatments for neurological disorders. Clinical studies considering sex biases and basic research on animal models have provided much evidence for the existence of sex differences in the brain and, in a larger sense, sexual dimorphisms in the nervous system. However, due to the complexity of structure and dimorphic behaviors, it is yet unclear precisely how neuronal sexual dimorphisms are regulated on a molecular or cellular level. This commentary reviews available tools for investigating sexual dimorphisms using a simple model organism, the roundworm Caenorhabditis elegans ( C. elegans), which enables one to study gene regulation at single-cell resolution with a number of cutting-edge molecular and genetic technologies. I highlight the doublesex/mab-3 family of transcription factors, first discovered in invertebrates, and their roles in a potentially universal regulatory mechanism underlying neuronal sexual dimorphisms. Studies of these transcription factors using C. elegans, fruit flies, and vertebrates will promote our understanding of fundamental mechanisms behind sex differences in the brain.
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Affiliation(s)
- Chen Wang
- Department of Biological Sciences, Columbia University, New York, NY, USA
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50
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Hilbert ZA, Kim DH. PDF-1 neuropeptide signaling regulates sexually dimorphic gene expression in shared sensory neurons of C. elegans. eLife 2018; 7:36547. [PMID: 30024377 PMCID: PMC6053303 DOI: 10.7554/elife.36547] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/05/2018] [Indexed: 12/23/2022] Open
Abstract
Sexually dimorphic behaviors are a feature common to species across the animal kingdom, however how such behaviors are generated from mostly sex-shared nervous systems is not well understood. Building on our previous work which described the sexually dimorphic expression of a neuroendocrine ligand, DAF-7, and its role in behavioral decision-making in C. elegans (Hilbert and Kim, 2017), we show here that sex-specific expression of daf-7 is regulated by another neuroendocrine ligand, Pigment Dispersing Factor (PDF-1), which has previously been implicated in regulating male-specific behavior (Barrios et al., 2012). Our analysis revealed that PDF-1 signaling acts sex- and cell-specifically in the ASJ neurons to regulate the expression of daf-7, and we show that differences in PDFR-1 receptor activity account for the sex-specific effects of this pathway. Our data suggest that modulation of the sex-shared nervous system by a cascade of neuroendocrine signals can shape sexually dimorphic behaviors.
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Affiliation(s)
- Zoë A Hilbert
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Dennis H Kim
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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