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Mika K, Benton R. Olfactory Receptor Gene Regulation in Insects: Multiple Mechanisms for Singular Expression. Front Neurosci 2021; 15:738088. [PMID: 34602974 PMCID: PMC8481607 DOI: 10.3389/fnins.2021.738088] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/24/2021] [Indexed: 12/25/2022] Open
Abstract
The singular expression of insect olfactory receptors in specific populations of olfactory sensory neurons is fundamental to the encoding of odors in patterns of neuronal activity in the brain. How a receptor gene is selected, from among a large repertoire in the genome, to be expressed in a particular neuron is an outstanding question. Focusing on Drosophila melanogaster, where most investigations have been performed, but incorporating recent insights from other insect species, we review the multilevel regulatory mechanisms of olfactory receptor expression. We discuss how cis-regulatory elements, trans-acting factors, chromatin modifications, and feedback pathways collaborate to activate and maintain expression of the chosen receptor (and to suppress others), highlighting similarities and differences with the mechanisms underlying singular receptor expression in mammals. We also consider the plasticity of receptor regulation in response to environmental cues and internal state during the lifetime of an individual, as well as the evolution of novel expression patterns over longer timescales. Finally, we describe the mechanisms and potential significance of examples of receptor co-expression.
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Affiliation(s)
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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2
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Behavioral and Transcriptional Response to Selection for Olfactory Behavior in Drosophila. G3-GENES GENOMES GENETICS 2020; 10:1283-1296. [PMID: 32024668 PMCID: PMC7144070 DOI: 10.1534/g3.120.401117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The detection, discrimination, and behavioral responses to chemical cues in the environment can have marked effects on organismal survival and reproduction, eliciting attractive or aversive behavior. To gain insight into mechanisms mediating this hedonic valence, we applied thirty generations of divergent artificial selection for Drosophila melanogaster olfactory behavior. We independently selected for positive and negative behavioral responses to two ecologically relevant chemical compounds: 2,3-butanedione and cyclohexanone. We also tested the correlated responses to selection by testing behavioral responses to other odorants and life history traits. Measurements of behavioral responses of the selected lines and unselected controls to additional odorants showed that the mechanisms underlying responses to these odorants are, in some cases, differentially affected by selection regime and generalization of the response to other odorants was only detected in the 2,3-butanedione selection lines. Food consumption and lifespan varied with selection regime and, at times, sex. An analysis of gene expression of both selection regimes identified multiple differentially expressed genes. New genes and genes previously identified in mediating olfactory behavior were identified. In particular, we found functional enrichment of several gene ontology terms, including cell-cell adhesion and sulfur compound metabolic process, the latter including genes belonging to the glutathione S-transferase family. These findings highlight a potential role for glutathione S-transferases in the evolution of hedonic valence to ecologically relevant volatile compounds and set the stage for a detailed investigation into mechanisms by which these genes mediate attraction and aversion.
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3
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Yan H, Jafari S, Pask G, Zhou X, Reinberg D, Desplan C. Evolution, developmental expression and function of odorant receptors in insects. J Exp Biol 2020; 223:jeb208215. [PMID: 32034042 PMCID: PMC7790194 DOI: 10.1242/jeb.208215] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Animals rely on their chemosensory system to discriminate among a very large number of attractive or repulsive chemical cues in the environment, which is essential to respond with proper action. The olfactory sensory systems in insects share significant similarities with those of vertebrates, although they also exhibit dramatic differences, such as the molecular nature of the odorant receptors (ORs): insect ORs function as heteromeric ion channels with a common Orco subunit, unlike the G-protein-coupled olfactory receptors found in vertebrates. Remarkable progress has recently been made in understanding the evolution, development and function of insect odorant receptor neurons (ORNs). These studies have uncovered the diversity of olfactory sensory systems among insect species, including in eusocial insects that rely extensively on olfactory sensing of pheromones for social communication. However, further studies, notably functional analyses, are needed to improve our understanding of the origins of the Orco-OR system, the mechanisms of ORN fate determination, and the extraordinary diversity of behavioral responses to chemical cues.
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Affiliation(s)
- Hua Yan
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- Center for Smell and Taste (UFCST), University of Florida, Gainesville, FL 32610, USA
| | - Shadi Jafari
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
- Department of Biology, New York University, New York, NY 10003, USA
| | - Gregory Pask
- Department of Biology, Bucknell University, Lewisburg, PA 17837, USA
| | - Xiaofan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, 510642 Guangzhou, China
| | - Danny Reinberg
- Howard Hughes Medical Institute (HHMI), Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA
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4
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Chai PC, Cruchet S, Wigger L, Benton R. Sensory neuron lineage mapping and manipulation in the Drosophila olfactory system. Nat Commun 2019; 10:643. [PMID: 30733440 PMCID: PMC6367400 DOI: 10.1038/s41467-019-08345-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/28/2018] [Indexed: 11/20/2022] Open
Abstract
Nervous systems exhibit myriad cell types, but understanding how this diversity arises is hampered by the difficulty to visualize and genetically-probe specific lineages, especially at early developmental stages prior to expression of unique molecular markers. Here, we use a genetic immortalization method to analyze the development of sensory neuron lineages in the Drosophila olfactory system, from their origin to terminal differentiation. We apply this approach to define a fate map of nearly all olfactory lineages and refine the model of temporal patterns of lineage divisions. Taking advantage of a selective marker for the lineage that gives rise to Or67d pheromone-sensing neurons and a genome-wide transcription factor RNAi screen, we identify the spatial and temporal requirements for Pointed, an ETS family member, in this developmental pathway. Transcriptomic analysis of wild-type and Pointed-depleted olfactory tissue reveals a universal requirement for this factor as a switch-like determinant of fates in these sensory lineages. Few tools exist to study molecular diversity during neurodevelopment. Here the authors apply a genetic immortalization method in Drosophila to generate a fate map of olfactory sensory lineages, examine the relationships of this map and the neuroanatomical, molecular and evolutionary properties of the mature circuits, and identify a novel factor controlling lineage development.
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Affiliation(s)
- Phing Chian Chai
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Steeve Cruchet
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Leonore Wigger
- Lausanne Genomic Technologies Facility, Génopode Building, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland.,Vital-IT Group, SIB Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Richard Benton
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland.
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5
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Slankster E, Odell SR, Mathew D. Strength in diversity: functional diversity among olfactory neurons of the same type. J Bioenerg Biomembr 2019; 51:65-75. [PMID: 30604088 PMCID: PMC6382560 DOI: 10.1007/s10863-018-9779-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/13/2018] [Indexed: 01/01/2023]
Abstract
Most animals depend upon olfaction to find food, mates, and to avoid predators. An animal's olfactory circuit helps it sense its olfactory environment and generate critical behavioral responses. The general architecture of the olfactory circuit, which is conserved across species, is made up of a few different neuronal types including first-order receptor neurons, second- and third-order neurons, and local interneurons. Each neuronal type differs in their morphology, physiology, and neurochemistry. However, several recent studies have suggested that there is intrinsic diversity even among neurons of the same type and that this diversity is important for neural function. In this review, we first examine instances of intrinsic diversity observed among individual types of olfactory neurons. Next, we review potential genetic and experience-based plasticity mechanisms that underlie this diversity. Finally, we consider the implications of intrinsic neuronal diversity for circuit function. Overall, we hope to highlight the importance of intrinsic diversity as a previously underestimated property of circuit function.
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Affiliation(s)
- Eryn Slankster
- Department of Biology, University of Nevada, 1664 N. Virginia St., MS: 0314, Reno, NV, 89557, USA
| | - Seth R Odell
- Department of Biology, University of Nevada, 1664 N. Virginia St., MS: 0314, Reno, NV, 89557, USA
- Integrated Neuroscience Program, University of Nevada, Reno, NV, 89557, USA
| | - Dennis Mathew
- Department of Biology, University of Nevada, 1664 N. Virginia St., MS: 0314, Reno, NV, 89557, USA.
- Integrated Neuroscience Program, University of Nevada, Reno, NV, 89557, USA.
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6
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Combinations of DIPs and Dprs control organization of olfactory receptor neuron terminals in Drosophila. PLoS Genet 2018; 14:e1007560. [PMID: 30102700 PMCID: PMC6107282 DOI: 10.1371/journal.pgen.1007560] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/23/2018] [Accepted: 07/13/2018] [Indexed: 12/22/2022] Open
Abstract
In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe. Despite the identification of cell surface receptors regulating axon guidance, how ORN axons sort to form 50 stereotypical glomeruli remains unclear. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. DIP/Dpr profiles are dynamic during development and correlate with sensilla type lineage for some ORN classes. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli. In the human brain there are over 80 billion neurons that form approximately 100 trillion specific connections. How the brain organizes the axon terminals of these neurons into distinct synaptic units on such a large scale is largely unknown. In Drosophila, 50 classes of olfactory receptor neurons (ORNs) connect to 50 class-specific and uniquely positioned glomeruli in the antennal lobe, providing a complex yet workable model to understand the organization of glomerular structures and morphology. Here we show that the heterophilic cell adhesion proteins, DIPs and Dprs, are expressed in ORNs during glomerular formation. Many ORN classes express a unique combination of DIPs/dprs, with neurons of the same class expressing interacting partners, suggesting a role in class-specific self-adhesion between ORN axons. Analysis of DIP/Dpr expression revealed that ORNs that target neighboring glomeruli have different combinations, and ORNs with very similar DIP/Dpr combinations can project to distant glomeruli in the antennal lobe. Perturbations of DIP/dpr gene function result in local projection defects of ORN axons and glomerular positioning, without altering correct matching of ORNs with their target neurons. Our results suggest that context-dependent differential adhesion through DIP/Dpr combinations regulate self-adhesion and sort ORN axons into uniquely positioned glomeruli.
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7
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Barish S, Volkan PC. Preparing Developing Peripheral Olfactory Tissue for Molecular and Immunohistochemical Analysis in Drosophila. J Vis Exp 2018. [PMID: 29985372 DOI: 10.3791/57716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The olfactory system of Drosophila is a widely used system in developmental neurobiology, systems neuroscience, as well as neurophysiology, behavior, and behavioral evolution. Drosophila olfactory tissues house the olfactory receptor neurons (ORNs) that detect volatile chemical cues in addition to hydro- and thermo-sensory neurons. In this protocol, we describe the dissection of developing peripheral olfactory tissue of the adult Drosophila species. We first describe how to stage and age Drosophila larvae, followed by the dissection of the antennal disc from early pupal stages, followed by the dissection of the antennae from mid-pupal stages and adults. We also show methods where preparations can be utilized in molecular techniques, such as the RNA extraction for qRT-PCR, RNAseq, or immunohistochemistry. These methods can also be applied to other Drosophila species after species-specific pupal development times are determined, and respective stages are calculated for appropriate aging.
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8
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Pan JW, Li Q, Barish S, Okuwa S, Zhao S, Soeder C, Kanke M, Jones CD, Volkan PC. Patterns of transcriptional parallelism and variation in the developing olfactory system of Drosophila species. Sci Rep 2017; 7:8804. [PMID: 28821769 PMCID: PMC5562767 DOI: 10.1038/s41598-017-08563-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/13/2017] [Indexed: 11/09/2022] Open
Abstract
Organisms have evolved strikingly parallel phenotypes in response to similar selection pressures suggesting that there may be shared constraints limiting the possible evolutionary trajectories. For example, the behavioral adaptation of specialist Drosophila species to specific host plants can exhibit parallel changes in their adult olfactory neuroanatomy. We investigated the genetic basis of these parallel changes by comparing gene expression during the development of the olfactory system of two specialist Drosophila species to that of four other generalist species. Our results suggest that the parallelism observed in the adult olfactory neuroanatomy of ecological specialists extends more broadly to their developmental antennal expression profiles, and to the transcription factor combinations specifying olfactory receptor neuron (ORN) fates. Additionally, comparing general patterns of variation for the antennal transcriptional profiles in the adult and developing olfactory system of the six species suggest the possibility that specific, non-random components of the developmental programs underlying the Drosophila olfactory system harbor a disproportionate amount of interspecies variation. Further examination of these developmental components may be able to inform a deeper understanding of how traits evolve.
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Affiliation(s)
- Jia Wern Pan
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Qingyun Li
- Department of Biology, Stanford University, Stanford, California, USA
| | - Scott Barish
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Sumie Okuwa
- Pratt School of Engineering, Duke University, Durham, North Carolina, USA
| | - Songhui Zhao
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Charles Soeder
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Matthew Kanke
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Corbin D Jones
- Department of Biology and Integrative Program for Biological & Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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9
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Pan JW, McLaughlin J, Yang H, Leo C, Rambarat P, Okuwa S, Monroy-Eklund A, Clark S, Jones CD, Volkan PC. Comparative analysis of behavioral and transcriptional variation underlying CO 2 sensory neuron function and development in Drosophila. Fly (Austin) 2017. [PMID: 28644712 DOI: 10.1080/19336934.2017.1344374] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Carbon dioxide is an important environmental cue for many insects, regulating many behaviors including some that have direct human impacts. To further improve our understanding of how this system varies among closely related insect species, we examined both the behavioral response to CO2 as well as the transcriptional profile of key developmental regulators of CO2 sensory neurons in the olfactory system across the Drosophila genus. We found that CO2 generally evokes repulsive behavior across most of the Drosophilids we examined, but this behavior has been lost or reduced in several lineages. Comparisons of transcriptional profiles from the developing and adult antennae for subset these species suggest that behavioral differences in some species may be due to differences in the expression of the CO2 co-receptor Gr63a. Furthermore, these differences in Gr63a expression are correlated with changes in the expression of a few genes known to be involved in the development of the CO2 circuit, namely dac, an important regulator of sensilla fate for sensilla that house CO2 ORNs, and mip120, a member of the MMB/dREAM epigenetic regulatory complex that regulates CO2 receptor expression. In contrast, most of the other known structural, molecular, and developmental components of the peripheral Drosophila CO2 olfactory system seem to be well-conserved across all examined lineages. These findings suggest that certain components of CO2 sensory ORN development may be more evolutionarily labile, and may contribute to differences in CO2-evoked behavioral responses across species.
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Affiliation(s)
- Jia Wern Pan
- a Department of Biology , Duke University , Durham , North Carolina
| | - Joi McLaughlin
- a Department of Biology , Duke University , Durham , North Carolina
| | - Haining Yang
- a Department of Biology , Duke University , Durham , North Carolina
| | - Charles Leo
- a Department of Biology , Duke University , Durham , North Carolina
| | - Paula Rambarat
- a Department of Biology , Duke University , Durham , North Carolina
| | - Sumie Okuwa
- b Pratt School of Engineering , Duke University , Durham , North Carolina
| | - Anaïs Monroy-Eklund
- c Department of Biology , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina
| | - Sabrina Clark
- c Department of Biology , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina
| | - Corbin D Jones
- c Department of Biology , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina
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10
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Hsieh YW, Alqadah A, Chuang CF. Mechanisms controlling diversification of olfactory sensory neuron classes. Cell Mol Life Sci 2017; 74:3263-3274. [PMID: 28357469 DOI: 10.1007/s00018-017-2512-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/28/2017] [Accepted: 03/21/2017] [Indexed: 12/25/2022]
Abstract
Animals survive in harsh and fluctuating environments using sensory neurons to detect and respond to changes in their surroundings. Olfactory sensory neurons are essential for detecting food, identifying danger, and sensing pheromones. The ability to sense a large repertoire of different types of odors is crucial to distinguish between different situations, and is achieved through neuronal diversity within the olfactory system. Here, we review the developmental mechanisms used to establish diversity of olfactory sensory neurons in various model organisms, including Caenorhabditis elegans, Drosophila, and vertebrate models. Understanding and comparing how different olfactory neurons develop within the nervous system of different animals can provide insight into how the olfactory system is shaped in humans.
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Affiliation(s)
- Yi-Wen Hsieh
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue, MC 567, Chicago, IL, 60607, USA
| | - Amel Alqadah
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue, MC 567, Chicago, IL, 60607, USA
| | - Chiou-Fen Chuang
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue, MC 567, Chicago, IL, 60607, USA.
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11
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Barish S, Li Q, Pan JW, Soeder C, Jones C, Volkan PC. Transcriptional profiling of olfactory system development identifies distal antenna as a regulator of subset of neuronal fates. Sci Rep 2017; 7:40873. [PMID: 28102318 PMCID: PMC5244397 DOI: 10.1038/srep40873] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/13/2016] [Indexed: 01/22/2023] Open
Abstract
Drosophila uses 50 different olfactory receptor neuron (ORN) classes that are clustered within distinct sensilla subtypes to decipher their chemical environment. Each sensilla subtype houses 1-4 ORN identities that arise through asymmetric divisions of a single sensory organ precursor (SOP). Despite a number of mutational studies investigating the regulation of ORN development, a majority of the transcriptional programs that lead to the different ORN classes in the developing olfactory system are unknown. Here we use transcriptional profiling across the time series of antennal development to identify novel transcriptional programs governing the differentiation of ORNs. We surveyed four critical developmental stages of the olfactory system: 3rd instar larval (prepatterning), 8 hours after puparium formation (APF, SOP selection), 40 hrs APF (neurogenesis), and adult antennae. We focused on the expression profiles of olfactory receptor genes and transcription factors-the two main classes of genes that regulate the sensory identity of ORNs. We identify distinct clusters of genes that have overlapping temporal expression profiles suggesting they have a key role during olfactory system development. We show that the expression of the transcription factor distal antenna (dan) is highly similar to other prepatterning factors and is required for the expression of a subset of ORs.
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Affiliation(s)
- Scott Barish
- Duke University, Department of Biology, Durham, NC, USA
| | - Qingyun Li
- Duke University, Department of Biology, Durham, NC, USA
| | - Jia W. Pan
- Duke University, Department of Biology, Durham, NC, USA
| | - Charlie Soeder
- University of North Carolina- Chapel Hill, Integrative Program for Biological & Genome Sciences, Chapel Hill, NC, USA
| | - Corbin Jones
- University of North Carolina- Chapel Hill, Integrative Program for Biological & Genome Sciences, Chapel Hill, NC, USA
- University of North Carolina- Chapel Hill, Department of Biology, Chapel Hill, NC, USA
| | - Pelin C. Volkan
- Duke University, Department of Biology, Durham, NC, USA
- Duke Institute for Brain Sciences, Durham, NC, USA
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12
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Arlotta P, Hobert O. Homeotic Transformations of Neuronal Cell Identities. Trends Neurosci 2016; 38:751-762. [PMID: 26596501 DOI: 10.1016/j.tins.2015.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/13/2015] [Accepted: 10/18/2015] [Indexed: 11/20/2022]
Abstract
Homeosis is classically defined as the transformation of one body part into something that resembles another body part. We propose here to broaden the concept of homeosis to the many neuronal cell identity transformations that have been uncovered over the past few years upon removal of specific regulatory factors in organisms from Caenorhabditis elegans to Drosophila, zebrafish, and mice. The concept of homeosis provides a framework for the evolution of cell type diversity in the brain.
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Affiliation(s)
- Paola Arlotta
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Oliver Hobert
- Department of Biology and Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, NY, USA.
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13
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Corty MM, Tam J, Grueber WB. Dendritic diversification through transcription factor-mediated suppression of alternative morphologies. Development 2016; 143:1351-62. [PMID: 27095495 DOI: 10.1242/dev.130906] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 02/25/2016] [Indexed: 01/23/2023]
Abstract
Neurons display a striking degree of functional and morphological diversity, and the developmental mechanisms that underlie diversification are of significant interest for understanding neural circuit assembly and function. We find that the morphology of Drosophila sensory neurons is diversified through a series of suppressive transcriptional interactions involving the POU domain transcription factors Pdm1 (Nubbin) and Pdm2, the homeodomain transcription factor Cut, and the transcriptional regulators Scalloped and Vestigial. Pdm1 and Pdm2 are expressed in a subset of proprioceptive sensory neurons and function to inhibit dendrite growth and branching. A subset of touch receptors show a capacity to express Pdm1/2, but Cut represses this expression and promotes more complex dendritic arbors. Levels of Cut expression are diversified in distinct sensory neurons by selective expression of Scalloped and Vestigial. Different levels of Cut impact dendritic complexity and, consistent with this, we show that Scalloped and Vestigial suppress terminal dendritic branching. This transcriptional hierarchy therefore acts to suppress alternative morphologies to diversify three distinct types of somatosensory neurons.
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Affiliation(s)
- Megan M Corty
- Department of Neuroscience, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
| | - Justina Tam
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
| | - Wesley B Grueber
- Department of Neuroscience, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
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14
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Hueston CE, Olsen D, Li Q, Okuwa S, Peng B, Wu J, Volkan PC. Chromatin Modulatory Proteins and Olfactory Receptor Signaling in the Refinement and Maintenance of Fruitless Expression in Olfactory Receptor Neurons. PLoS Biol 2016; 14:e1002443. [PMID: 27093619 PMCID: PMC4836687 DOI: 10.1371/journal.pbio.1002443] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/17/2016] [Indexed: 11/18/2022] Open
Abstract
During development, sensory neurons must choose identities that allow them to detect specific signals and connect with appropriate target neurons. Ultimately, these sensory neurons will successfully integrate into appropriate neural circuits to generate defined motor outputs, or behavior. This integration requires a developmental coordination between the identity of the neuron and the identity of the circuit. The mechanisms that underlie this coordination are currently unknown. Here, we describe two modes of regulation that coordinate the sensory identities of Drosophila melanogaster olfactory receptor neurons (ORNs) involved in sex-specific behaviors with the sex-specific behavioral circuit identity marker fruitless (fru). The first mode involves a developmental program that coordinately restricts to appropriate ORNs the expression of fru and two olfactory receptors (Or47b and Ir84a) involved in sex-specific behaviors. This regulation requires the chromatin modulatory protein Alhambra (Alh). The second mode relies on the signaling from the olfactory receptors through CamK and histone acetyl transferase p300/CBP to maintain ORN-specific fru expression. Our results highlight two feed-forward regulatory mechanisms with both developmentally hardwired and olfactory receptor activity-dependent components that establish and maintain fru expression in ORNs. Such a dual mechanism of fru regulation in ORNs might be a trait of neurons driving plastic aspects of sex-specific behaviors.
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Affiliation(s)
- Catherine E. Hueston
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
| | - Douglas Olsen
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Qingyun Li
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Sumie Okuwa
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Bo Peng
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Jianni Wu
- Undergraduate Program in Neuroscience, Duke University, Durham, North Carolina, United States of America
| | - Pelin Cayirlioglu Volkan
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- Duke Institute for Brain Science, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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Li Q, Barish S, Okuwa S, Maciejewski A, Brandt AT, Reinhold D, Jones CD, Volkan PC. A Functionally Conserved Gene Regulatory Network Module Governing Olfactory Neuron Diversity. PLoS Genet 2016; 12:e1005780. [PMID: 26765103 PMCID: PMC4713227 DOI: 10.1371/journal.pgen.1005780] [Citation(s) in RCA: 32] [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: 10/26/2015] [Accepted: 12/08/2015] [Indexed: 12/21/2022] Open
Abstract
Sensory neuron diversity is required for organisms to decipher complex environmental cues. In Drosophila, the olfactory environment is detected by 50 different olfactory receptor neuron (ORN) classes that are clustered in combinations within distinct sensilla subtypes. Each sensilla subtype houses stereotypically clustered 1-4 ORN identities that arise through asymmetric divisions from a single multipotent sensory organ precursor (SOP). How each class of SOPs acquires a unique differentiation potential that accounts for ORN diversity is unknown. Previously, we reported a critical component of SOP diversification program, Rotund (Rn), increases ORN diversity by generating novel developmental trajectories from existing precursors within each independent sensilla type lineages. Here, we show that Rn, along with BarH1/H2 (Bar), Bric-à-brac (Bab), Apterous (Ap) and Dachshund (Dac), constitutes a transcription factor (TF) network that patterns the developing olfactory tissue. This network was previously shown to pattern the segmentation of the leg, which suggests that this network is functionally conserved. In antennal imaginal discs, precursors with diverse ORN differentiation potentials are selected from concentric rings defined by unique combinations of these TFs along the proximodistal axis of the developing antennal disc. The combinatorial code that demarcates each precursor field is set up by cross-regulatory interactions among different factors within the network. Modifications of this network lead to predictable changes in the diversity of sensilla subtypes and ORN pools. In light of our data, we propose a molecular map that defines each unique SOP fate. Our results highlight the importance of the early prepatterning gene regulatory network as a modulator of SOP and terminally differentiated ORN diversity. Finally, our model illustrates how conserved developmental strategies are used to generate neuronal diversity.
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Affiliation(s)
- Qingyun Li
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Scott Barish
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Sumie Okuwa
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Abigail Maciejewski
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Alicia T. Brandt
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Dominik Reinhold
- Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Mathematics and Computer Science, Clark University, Worcester, Massachusetts, United States of America
| | - Corbin D. Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Pelin Cayirlioglu Volkan
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- Duke Institute for Brain Sciences, Duke University, Durham, North Carolina, United States of America
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Abstract
Moth sexual pheromones are widely studied as a fine-tuned system of intraspecific sexual communication that reinforces interspecific reproductive isolation. However, their evolution poses a dilemma: How can the female pheromone and male preference simultaneously change to create a new pattern of species-specific attraction? Solving this puzzle requires us to identify the genes underlying intraspecific variation in signals and responses and to understand the evolutionary mechanisms responsible for their interspecific divergence. Candidate gene approaches and functional analyses have yielded insights into large families of biosynthetic enzymes and pheromone receptors, although the factors controlling their expression remain largely unexplored. Intra- and interspecific crosses have provided tantalizing evidence of regulatory genes, although, to date, mapping resolution has been insufficient to identify them. Recent advances in high-throughput genome and transcriptome sequencing, together with established techniques, have great potential to help scientists identify the specific genetic changes underlying divergence and resolve the mystery of how moth sexual communication systems evolve.
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Affiliation(s)
- Astrid T Groot
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands;
- Department of Entomology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany;
| | - Teun Dekker
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden;
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany;
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Li Q, Barish S, Okuwa S, Volkan PC. Examination of Endogenous Rotund Expression and Function in Developing Drosophila Olfactory System Using CRISPR-Cas9-Mediated Protein Tagging. G3 (BETHESDA, MD.) 2015; 5:2809-16. [PMID: 26497147 PMCID: PMC4683652 DOI: 10.1534/g3.115.021857] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/12/2015] [Indexed: 02/05/2023]
Abstract
The zinc-finger protein Rotund (Rn) plays a critical role in controlling the development of the fly olfactory system. However, little is known about its molecular function in vivo. Here, we added protein tags to the rn locus using CRISPR-Cas9 technology in Drosophila to investigate its subcellular localization and the genes that it regulates . We previously used a reporter construct to show that rn is expressed in a subset of olfactory receptor neuron (ORN) precursors and it is required for the diversification of ORN fates. Here, we show that tagged endogenous Rn protein is functional based on the analysis of ORN phenotypes. Using this method, we also mapped the expression pattern of the endogenous isoform-specific tags in vivo with increased precision. Comparison of the Rn expression pattern from this study with previously published results using GAL4 reporters showed that Rn is mainly present in early steps in antennal disc patterning, but not in pupal stages when ORNs are born. Finally, using chromatin immunoprecipitation, we showed a direct binding of Rotund to a previously identified regulatory element upstream of the bric-a-brac gene locus in the developing antennal disc.
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Affiliation(s)
- Qingyun Li
- Department of Biology, Duke University, Durham, North Carolina 27708
| | - Scott Barish
- Department of Biology, Duke University, Durham, North Carolina 27708
| | - Sumie Okuwa
- Department of Biology, Duke University, Durham, North Carolina 27708
| | - Pelin C Volkan
- Department of Biology, Duke University, Durham, North Carolina 27708 Duke Institute for Brain Sciences, Duke University, Durham, North Carolina 27708
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18
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Joseph RM, Carlson JR. Drosophila Chemoreceptors: A Molecular Interface Between the Chemical World and the Brain. Trends Genet 2015; 31:683-695. [PMID: 26477743 DOI: 10.1016/j.tig.2015.09.005] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/25/2015] [Accepted: 09/08/2015] [Indexed: 10/22/2022]
Abstract
Chemoreception is essential for survival. Feeding, mating, and avoidance of predators depend on detection of sensory cues. Drosophila contains diverse families of chemoreceptors that detect odors, tastants, pheromones, and noxious stimuli, including receptors of the odor receptor (Or), gustatory receptor (Gr), ionotropic receptor (IR), Pickpocket (Ppk), and Trp families. We consider recent progress in understanding chemoreception in the fly, including the identification of new receptors, the discovery of novel biological functions for receptors, and the localization of receptors in unexpected places. We discuss major unsolved problems and suggest areas that may be particularly ripe for future discoveries, including the roles of these receptors in driving the circuits and behaviors that are essential to the survival and reproduction of the animal.
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Affiliation(s)
- Ryan M Joseph
- Department of Molecular, Cellular, and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA
| | - John R Carlson
- Department of Molecular, Cellular, and Developmental Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA.
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Barish S, Volkan PC. Mechanisms of olfactory receptor neuron specification in Drosophila. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:609-21. [PMID: 26088441 PMCID: PMC4744966 DOI: 10.1002/wdev.197] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 05/04/2015] [Accepted: 05/16/2015] [Indexed: 11/05/2022]
Abstract
Detection of a broad range of chemosensory signals is necessary for the survival of multicellular organisms. Chemical signals are the main facilitators of foraging, escape, and social behaviors. To increase detection coverage, animal sensory systems have evolved to create a large number of neurons with highly specific functions. The olfactory system, much like the nervous system as a whole, is astonishingly diverse. The mouse olfactory system has millions of neurons with over a thousand classes, whereas the more compact Drosophila genome has approximately 80 odorant receptor genes that give rise to 50 neuronal classes and 1300 neurons in the adult.(4) Understanding how neuronal diversity is generated remains one of the central questions in developmental neurobiology. Here, we review the current knowledge on the development of the adult Drosophila olfactory system and the progress that has been made toward answering this central question.
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Affiliation(s)
- Scott Barish
- Department of Biology, Duke University, Durham, NC, USA
| | - Pelin Cayirlioglu Volkan
- Department of Biology, Duke University, Durham, NC, USA.,Duke Institute of Brain Sciences, Duke University, Durham, NC, USA
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21
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Engrailed alters the specificity of synaptic connections of Drosophila auditory neurons with the giant fiber. J Neurosci 2014; 34:11691-704. [PMID: 25164665 DOI: 10.1523/jneurosci.1939-14.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We show that a subset of sound-detecting Johnston's Organ neurons (JONs) in Drosophila melanogaster, which express the transcription factors Engrailed (En) and Invected (Inv), form mixed electrical and chemical synaptic inputs onto the giant fiber (GF) dendrite. These synaptic connections are detected by trans-synaptic Neurobiotin (NB) transfer and by colocalization of Bruchpilot-short puncta. We then show that misexpressing En postmitotically in a second subset of sound-responsive JONs causes them to form ectopic electrical and chemical synapses with the GF, in turn causing that postsynaptic neuron to redistribute its dendritic branches into the vicinity of these afferents. We also introduce a simple electrophysiological recording paradigm for quantifying the presynaptic and postsynaptic electrical activity at this synapse, by measuring the extracellular sound-evoked potentials (SEPs) from the antennal nerve while monitoring the likelihood of the GF firing an action potential in response to simultaneous subthreshold sound and voltage stimuli. Ectopic presynaptic expression of En strengthens the synaptic connection, consistent with there being more synaptic contacts formed. Finally, RNAi-mediated knockdown of En and Inv in postmitotic neurons reduces SEP amplitude but also reduces synaptic strength at the JON-GF synapse. Overall, these results suggest that En and Inv in JONs regulate both neuronal excitability and synaptic connectivity.
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Wernet MF, Desplan C. Sensory cell fates: four defaults for the price of one. Curr Biol 2013; 23:R1089-91. [PMID: 24355782 DOI: 10.1016/j.cub.2013.10.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The specification of different subtypes of olfactory sensilla, which harbor the olfactory receptor neurons (ORNs) in the Drosophila antennae, is poorly understood. Loss of the transcription factor Rotund (Rn) leads to a simultaneous mis-specification of several ORN classes, transforming them into different 'default' cell fates.
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Affiliation(s)
- Mathias F Wernet
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA
| | - Claude Desplan
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Square East, New York, NY 10003-6688, USA.
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