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Ray L, Medeiros D. Linking Vertebrate Gene Duplications to the New Head Hypothesis. BIOLOGY 2023; 12:1213. [PMID: 37759612 PMCID: PMC10525774 DOI: 10.3390/biology12091213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/11/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023]
Abstract
Vertebrates have diverse morphologies and various anatomical novelties that set them apart from their closest invertebrate relatives. A conspicuous head housing a large brain, paired sense organs, and protected by a skeleton of cartilage and bone is unique to vertebrates and is a defining feature of this taxon. Gans and Northcutt (1980s) proposed that the evolution of this "new head" was dependent on two key developmental innovations: neural crest cells (NCCs) and ectodermal placodes. NCCs are migratory embryonic cells that form bone, cartilage, and neurons in the new head. Based on genome size, Ohno (1970s) proposed a separate hypothesis, stating that vertebrate genome content was quadrupled via two rounds (2R) of whole genome duplications (WGDs), and the surplus of genetic material potentiated vertebrate morphological diversification. While both hypotheses offer explanations for vertebrate success, it is unclear if, and how, the "new head" and "2R" hypotheses are linked. Here, we consider both hypotheses and evaluate the experimental evidence connecting the two. Overall, evidence suggests that while the origin of the NC GRN predates the vertebrate WGDs, these genomic events may have potentiated the evolution of distinct genetic subnetworks in different neural crest subpopulations. We describe the general composition of the NC GRN and posit that its increased developmental modularity facilitated the independent evolution of NC derivatives and the diversification of the vertebrate head skeleton. Lastly, we discuss experimental strategies needed to test whether gene duplications drove the diversification of neural crest derivatives and the "new head".
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Affiliation(s)
- Lindsey Ray
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Daniel Medeiros
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
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2
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Razin SV, Ioudinkova ES, Kantidze OL, Iarovaia OV. Co-Regulated Genes and Gene Clusters. Genes (Basel) 2021; 12:907. [PMID: 34208174 PMCID: PMC8230824 DOI: 10.3390/genes12060907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 12/27/2022] Open
Abstract
There are many co-regulated genes in eukaryotic cells. The coordinated activation or repression of such genes occurs at specific stages of differentiation, or under the influence of external stimuli. As a rule, co-regulated genes are dispersed in the genome. However, there are also gene clusters, which contain paralogous genes that encode proteins with similar functions. In this aspect, they differ significantly from bacterial operons containing functionally linked genes that are not paralogs. In this review, we discuss the reasons for the existence of gene clusters in vertebrate cells and propose that clustering is necessary to ensure the possibility of selective activation of one of several similar genes.
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Affiliation(s)
- Sergey V. Razin
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia; (E.S.I.); (O.L.K.); (O.V.I.)
- Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Elena S. Ioudinkova
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia; (E.S.I.); (O.L.K.); (O.V.I.)
| | - Omar L. Kantidze
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia; (E.S.I.); (O.L.K.); (O.V.I.)
| | - Olga V. Iarovaia
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia; (E.S.I.); (O.L.K.); (O.V.I.)
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3
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Lei Y, Yang L, Jiang H, Chen J, Sun N, Lv W, He S. Recent genome duplications facilitate the phenotypic diversity of Hb repertoire in the Cyprinidae. SCIENCE CHINA-LIFE SCIENCES 2020; 64:1149-1164. [PMID: 33051703 DOI: 10.1007/s11427-020-1809-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/28/2020] [Indexed: 12/11/2022]
Abstract
Whole-genome duplications (WGDs) are an important contributor to phenotypic innovations in evolutionary history. The diversity of blood oxygen transport traits is the perfect reflection of physiological versatility for evolutionary success among vertebrates. In this study, the evolutionary changes of hemoglobin (Hb) repertoire driven by the recent genome duplications were detected in representative Cyprinidae fish, including eight diploid and four tetraploid species. Comparative genomic analysis revealed a substantial variation in both membership composition and intragenomic organization of Hb genes in these species. Phylogenetic reconstruction analyses were conducted to characterize the evolutionary history of these genes. Data were integrated with the expression profiles of the genes during ontogeny. Our results indicated that genome duplications facilitated the phenotypic diversity of the Hb gene family; each was associated with species-specific changes in gene content via gene loss and fusion after genome duplications. This led to repeated evolutionary transitions in the ontogenic regulation of Hb gene expression. Our results revealed that genome duplications helped to generate phenotypic changes in Cyprinidae Hb systems.
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Affiliation(s)
- Yi Lei
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Liandong Yang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haifeng Jiang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Juan Chen
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ning Sun
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenqi Lv
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shunping He
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China. .,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China.
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4
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York JR, McCauley DW. The origin and evolution of vertebrate neural crest cells. Open Biol 2020; 10:190285. [PMID: 31992146 PMCID: PMC7014683 DOI: 10.1098/rsob.190285] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 01/06/2020] [Indexed: 12/13/2022] Open
Abstract
The neural crest is a vertebrate-specific migratory stem cell population that generates a remarkably diverse set of cell types and structures. Because many of the morphological, physiological and behavioural novelties of vertebrates are derived from neural crest cells, it is thought that the origin of this cell population was an important milestone in early vertebrate history. An outstanding question in the field of vertebrate evolutionary-developmental biology (evo-devo) is how this cell type evolved in ancestral vertebrates. In this review, we briefly summarize neural crest developmental genetics in vertebrates, focusing in particular on the gene regulatory interactions instructing their early formation within and migration from the dorsal neural tube. We then discuss how studies searching for homologues of neural crest cells in invertebrate chordates led to the discovery of neural crest-like cells in tunicates and the potential implications this has for tracing the pre-vertebrate origins of the neural crest population. Finally, we synthesize this information to propose a model to explain the origin of neural crest cells. We suggest that at least some of the regulatory components of early stages of neural crest development long pre-date vertebrate origins, perhaps dating back to the last common bilaterian ancestor. These components, originally directing neuroectodermal patterning and cell migration, served as a gene regulatory 'scaffold' upon which neural crest-like cells with limited migration and potency evolved in the last common ancestor of tunicates and vertebrates. Finally, the acquisition of regulatory programmes controlling multipotency and long-range, directed migration led to the transition from neural crest-like cells in invertebrate chordates to multipotent migratory neural crest in the first vertebrates.
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Affiliation(s)
| | - David W. McCauley
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
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5
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Andrews MG, Kong J, Novitch BG, Butler SJ. New perspectives on the mechanisms establishing the dorsal-ventral axis of the spinal cord. Curr Top Dev Biol 2018; 132:417-450. [PMID: 30797516 DOI: 10.1016/bs.ctdb.2018.12.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Distinct classes of neurons arise at different positions along the dorsal-ventral axis of the spinal cord leading to spinal neurons being segregated along this axis according to their physiological properties and functions. Thus, the neurons associated with motor control are generally located in, or adjacent to, the ventral horn whereas the interneurons (INs) that mediate sensory activities are present within the dorsal horn. Here, we review classic and recent studies examining the developmental mechanisms that establish the dorsal-ventral axis in the embryonic spinal cord. Intriguingly, while the cellular organization of the dorsal and ventral halves of the spinal cord looks superficially similar during early development, the underlying molecular mechanisms that establish dorsal vs ventral patterning are markedly distinct. For example, the ventral spinal cord is patterned by the actions of a single growth factor, sonic hedgehog (Shh) acting as a morphogen, i.e., concentration-dependent signal. Recent studies have shed light on the mechanisms by which the spatial and temporal gradient of Shh is transduced by cells to elicit the generation of different classes of ventral INs, and motor neurons (MNs). In contrast, the dorsal spinal cord is patterned by the action of multiple factors, most notably by members of the bone morphogenetic protein (BMP) and Wnt families. While less is known about dorsal patterning, recent studies have suggested that the BMPs do not act as morphogens to specify dorsal IN identities as previously proposed, rather each BMP has signal-specific activities. Finally, we consider the promise that elucidation of these mechanisms holds for neural repair.
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Affiliation(s)
- Madeline G Andrews
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Neuroscience Graduate Program, University of California, Los Angeles, CA, United States
| | - Jennifer Kong
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Neuroscience Graduate Program, University of California, Los Angeles, CA, United States
| | - Bennett G Novitch
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA, United States
| | - Samantha J Butler
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA, United States.
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6
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Square T, Jandzik D, Romášek M, Cerny R, Medeiros DM. The origin and diversification of the developmental mechanisms that pattern the vertebrate head skeleton. Dev Biol 2017; 427:219-229. [DOI: 10.1016/j.ydbio.2016.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/06/2016] [Accepted: 11/20/2016] [Indexed: 01/30/2023]
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7
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Sasakura Y, Ogura Y, Treen N, Yokomori R, Park SJ, Nakai K, Saiga H, Sakuma T, Yamamoto T, Fujiwara S, Yoshida K. Transcriptional regulation of a horizontally transferred gene from bacterium to chordate. Proc Biol Sci 2016; 283:20161712. [PMID: 28003446 PMCID: PMC5204163 DOI: 10.1098/rspb.2016.1712] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/15/2016] [Indexed: 01/21/2023] Open
Abstract
The horizontal transfer of genes between distantly related organisms is undoubtedly a major factor in the evolution of novel traits. Because genes are functionless without expression, horizontally transferred genes must acquire appropriate transcriptional regulations in their recipient organisms, although the evolutionary mechanism is not known well. The defining characteristic of tunicates is the presence of a cellulose containing tunic covering the adult and larval body surface. Cellulose synthase was acquired by horizontal gene transfer from Actinobacteria. We found that acquisition of the binding site of AP-2 transcription factor was essential for tunicate cellulose synthase to gain epidermal-specific expression. Actinobacteria have very GC-rich genomes, regions of which are capable of inducing specific expression in the tunicate epidermis as the AP-2 binds to a GC-rich region. Therefore, the actinobacterial cellulose synthase could have been potentiated to evolve its new function in the ancestor of tunicates with a higher probability than the evolution depending solely on a spontaneous event.
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Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Yosuke Ogura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Rui Yokomori
- The Institute of Medical Sciences, University of Tokyo, Tokyo 108-8639, Japan
| | - Sung-Joon Park
- The Institute of Medical Sciences, University of Tokyo, Tokyo 108-8639, Japan
| | - Kenta Nakai
- The Institute of Medical Sciences, University of Tokyo, Tokyo 108-8639, Japan
| | - Hidetoshi Saiga
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Shigeki Fujiwara
- Department of Applied Science, Kochi University, 2-5-1, Akebono-cho, Kochi-shi, Kochi 780-8520, Japan
| | - Keita Yoshida
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
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8
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Functional constraints on SoxE proteins in neural crest development: The importance of differential expression for evolution of protein activity. Dev Biol 2016; 418:166-178. [DOI: 10.1016/j.ydbio.2016.07.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 07/28/2016] [Accepted: 07/30/2016] [Indexed: 10/21/2022]
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9
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De Luca A, Cerrato V, Fucà E, Parmigiani E, Buffo A, Leto K. Sonic hedgehog patterning during cerebellar development. Cell Mol Life Sci 2016; 73:291-303. [PMID: 26499980 PMCID: PMC11108499 DOI: 10.1007/s00018-015-2065-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 10/06/2015] [Accepted: 10/08/2015] [Indexed: 01/30/2023]
Abstract
The morphogenic factor sonic hedgehog (Shh) actively orchestrates many aspects of cerebellar development and maturation. During embryogenesis, Shh signaling is active in the ventricular germinal zone (VZ) and represents an essential signal for proliferation of VZ-derived progenitors. Later, Shh secreted by Purkinje cells sustains the amplification of postnatal neurogenic niches: the external granular layer and the prospective white matter, where excitatory granule cells and inhibitory interneurons are produced, respectively. Moreover, Shh signaling affects Bergmann glial differentiation and promotes cerebellar foliation during development. Here we review the most relevant functions of Shh during cerebellar ontogenesis, underlying its role in physiological and pathological conditions.
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Affiliation(s)
- Annarita De Luca
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy
| | - Valentina Cerrato
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy
| | - Elisa Fucà
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy
| | - Elena Parmigiani
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy
| | - Annalisa Buffo
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy
| | - Ketty Leto
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, 10126, Turin, Italy.
- Neuroscience Institute Cavalieri Ottolenghi, Regione Gonzole 10, 10043, Orbassano, Turin, Italy.
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10
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Pino LCDM, Balassiano LKDA, Sessim M, de Almeida APM, Empinotti VD, Semenovitch I, Treu C, Lupi O. Basal cell nevus syndrome: clinical and molecular review and case report. Int J Dermatol 2015; 55:367-75. [PMID: 26356331 DOI: 10.1111/ijd.12993] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 12/06/2014] [Accepted: 01/25/2015] [Indexed: 11/28/2022]
Abstract
Basal cell nevus syndrome (BCNS), also referred to as nevoid basal cell carcinoma syndrome or Gorlin-Goltz syndrome, was first described by Gorlin and Goltz in 1960 as an autosomal dominant disorder characterized by the early appearance of multiple basal cell carcinomas (BCCs), keratocysts of the jaw, ectopic calcifications, palmar and plantar pits, and anomalies of the ocular, skeletal, and reproductive systems. The genesis of this cancer's etiology in relation to BCNS was unclear until a few years ago when molecular analysis studies suggested a relationship between BCC and the loss-of-function mutations of the patched gene (PTCH) found on chromosome arm 9q. PTCH inhibits signaling by the membrane protein Smoothened (Smo), and this inhibition is relieved by binding sonic hedgehog (SHH) to PTCH. We describe a patient with multiple BCCs associated with x-ray anomalies of BCNS and review the basis of the SHH signaling pathway and clinical aspects of BCNS.
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Affiliation(s)
| | | | - Marlene Sessim
- Department of Dermatology, Policlínica Geral do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | - Ivan Semenovitch
- Department of Dermatology, Policlínica Geral do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Curt Treu
- Department of Dermatology, Policlínica Geral do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Omar Lupi
- Department of Dermatology, Policlínica Geral do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Department of Dermatology, Universidade Federal do Estado do Rio de Janeiro (Unirio), Rio de Janeiro, RJ, Brazil.,Department of Dermatology, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
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11
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12
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Ono H, Kozmik Z, Yu JK, Wada H. A novel N-terminal motif is responsible for the evolution of neural crest-specific gene-regulatory activity in vertebrate FoxD3. Dev Biol 2013; 385:396-404. [PMID: 24252777 DOI: 10.1016/j.ydbio.2013.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/30/2013] [Accepted: 11/09/2013] [Indexed: 11/24/2022]
Abstract
The neural crest is unique to vertebrates and has allowed the evolution of their complicated craniofacial structures. During vertebrate evolution, the acquisition of the neural crest must have been accompanied by the emergence of a new gene regulatory network (GRN). Here, to investigate the role of protein evolution in the emergence of the neural crest GRN, we examined the neural crest cell (NCC) differentiation-inducing activity of chordate FoxD genes. Amphioxus and vertebrate (Xenopus) FoxD proteins both exhibited transcriptional repressor activity in Gal4 transactivation assays and bound to similar DNA sequences in vitro. However, whereas vertebrate FoxD3 genes induced the differentiation of ectopic NCCs when overexpressed in chick neural tube, neither amphioxus FoxD nor any other vertebrate FoxD paralogs exhibited this activity. Experiments using chimeric proteins showed that the N-terminal portion of the vertebrate FoxD3 protein is critical to its NCC differentiation-inducing activity. Furthermore, replacement of the N-terminus of amphioxus FoxD with a 39-amino-acid segment from zebrafish FoxD3 conferred neural crest-inducing activity on amphioxus FoxD or zebrafish FoxD1. Therefore, fixation of this N-terminal amino acid sequence may have been crucial in the evolutionary recruitment of FoxD3 to the vertebrate neural crest GRN.
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Affiliation(s)
- Hiroki Ono
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Zbynek Kozmik
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Jr-Kai Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan; Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan
| | - Hiroshi Wada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
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13
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Ivashkin E, Adameyko I. Progenitors of the protochordate ocellus as an evolutionary origin of the neural crest. EvoDevo 2013; 4:12. [PMID: 23575111 PMCID: PMC3626940 DOI: 10.1186/2041-9139-4-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/28/2012] [Indexed: 01/01/2023] Open
Abstract
The neural crest represents a highly multipotent population of embryonic stem cells found only in vertebrate embryos. Acquisition of the neural crest during the evolution of vertebrates was a great advantage, providing Chordata animals with the first cellular cartilage, bone, dentition, advanced nervous system and other innovations. Today not much is known about the evolutionary origin of neural crest cells. Here we propose a novel scenario in which the neural crest originates from neuroectodermal progenitors of the pigmented ocelli in Amphioxus-like animals. We suggest that because of changes in photoreception needs, these multipotent progenitors of photoreceptors gained the ability to migrate outside of the central nervous system and subsequently started to give rise to neural, glial and pigmented progeny at the periphery.
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Affiliation(s)
- Evgeniy Ivashkin
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheeles vag 1 A1, Stockholm 17177, Sweden.
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14
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Abitua PB, Wagner E, Navarrete IA, Levine M. Identification of a rudimentary neural crest in a non-vertebrate chordate. Nature 2012; 492:104-7. [PMID: 23135395 PMCID: PMC4257486 DOI: 10.1038/nature11589] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 09/13/2012] [Indexed: 11/15/2022]
Abstract
Neural crest arises at the neural plate border, expresses a core set of regulatory genes, and produces a diverse array of cell types including ectomesenchyme derivatives that elaborate the vertebrate head1,2. The evolution of neural crest has been postulated as a key event leading to the appearance of new cell types that fostered the transition from filter feeding to active predation in ancestral vertebrates3. However, the origin of neural crest remains controversial, since homologous cell types have not been unambiguously identified in non-vertebrate chordates1,4. Here we show that the tunicate Ciona intestinalis possesses a cephalic melanocyte lineage (a9.49) similar to neural crest that can be reprogrammed into migrating ectomesenchyme by the targeted misexpression of Twist. Our results suggest that the neural crest melanocyte regulatory network predated the divergence of tunicates and vertebrates. We propose that the co-option of mesenchyme determinants, such as Twist, into the neural plate ectoderm was crucial for the emergence of the vertebrate “new head”3.
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Affiliation(s)
- Philip Barron Abitua
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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15
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Opazo JC, Butts GT, Nery MF, Storz JF, Hoffmann FG. Whole-genome duplication and the functional diversification of teleost fish hemoglobins. Mol Biol Evol 2012; 30:140-53. [PMID: 22949522 PMCID: PMC3525417 DOI: 10.1093/molbev/mss212] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Subsequent to the two rounds of whole-genome duplication that occurred in the common
ancestor of vertebrates, a third genome duplication occurred in the stem lineage of
teleost fishes. This teleost-specific genome duplication (TGD) is thought to have provided
genetic raw materials for the physiological, morphological, and behavioral diversification
of this highly speciose group. The extreme physiological versatility of teleost fish is
manifest in their diversity of blood–gas transport traits, which reflects the myriad
solutions that have evolved to maintain tissue O2 delivery in the face of
changing metabolic demands and environmental O2 availability during different
ontogenetic stages. During the course of development, regulatory changes in
blood–O2 transport are mediated by the expression of multiple,
functionally distinct hemoglobin (Hb) isoforms that meet the particular
O2-transport challenges encountered by the developing embryo or fetus (in
viviparous or oviparous species) and in free-swimming larvae and adults. The main
objective of the present study was to assess the relative contributions of whole-genome
duplication, large-scale segmental duplication, and small-scale gene duplication in
producing the extraordinary functional diversity of teleost Hbs. To accomplish this, we
integrated phylogenetic reconstructions with analyses of conserved synteny to characterize
the genomic organization and evolutionary history of the globin gene clusters of teleosts.
These results were then integrated with available experimental data on functional
properties and developmental patterns of stage-specific gene expression. Our results
indicate that multiple α- and β-globin genes
were present in the common ancestor of gars (order Lepisoteiformes) and teleosts. The
comparative genomic analysis revealed that teleosts possess a dual set of TGD-derived
globin gene clusters, each of which has undergone lineage-specific changes in gene content
via repeated duplication and deletion events. Phylogenetic reconstructions revealed that
paralogous genes convergently evolved similar functional properties in different teleost
lineages. Consistent with other recent studies of globin gene family evolution in
vertebrates, our results revealed evidence for repeated evolutionary transitions in the
developmental regulation of Hb synthesis.
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Affiliation(s)
- Juan C Opazo
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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16
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Storz JF, Opazo JC, Hoffmann FG. Gene duplication, genome duplication, and the functional diversification of vertebrate globins. Mol Phylogenet Evol 2012; 66:469-78. [PMID: 22846683 DOI: 10.1016/j.ympev.2012.07.013] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 06/21/2012] [Accepted: 07/16/2012] [Indexed: 11/28/2022]
Abstract
The functional diversification of the vertebrate globin gene superfamily provides an especially vivid illustration of the role of gene duplication and whole-genome duplication in promoting evolutionary innovation. For example, key globin proteins that evolved specialized functions in various aspects of oxidative metabolism and oxygen signaling pathways (hemoglobin [Hb], myoglobin [Mb], and cytoglobin [Cygb]) trace their origins to two whole-genome duplication events in the stem lineage of vertebrates. The retention of the proto-Hb and Mb genes in the ancestor of jawed vertebrates permitted a physiological division of labor between the oxygen-carrier function of Hb and the oxygen-storage function of Mb. In the Hb gene lineage, a subsequent tandem gene duplication gave rise to the proto α- and β-globin genes, which permitted the formation of multimeric Hbs composed of unlike subunits (α(2)β(2)). The evolution of this heteromeric quaternary structure was central to the emergence of Hb as a specialized oxygen-transport protein because it provided a mechanism for cooperative oxygen-binding and allosteric regulatory control. Subsequent rounds of duplication and divergence have produced diverse repertoires of α- and β-like globin genes that are ontogenetically regulated such that functionally distinct Hb isoforms are expressed during different stages of prenatal development and postnatal life. In the ancestor of jawless fishes, the proto Mb and Hb genes appear to have been secondarily lost, and the Cygb homolog evolved a specialized respiratory function in blood-oxygen transport. Phylogenetic and comparative genomic analyses of the vertebrate globin gene superfamily have revealed numerous instances in which paralogous globins have convergently evolved similar expression patterns and/or similar functional specializations in different organismal lineages.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA.
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Hoffmann FG, Opazo JC, Storz JF. Whole-genome duplications spurred the functional diversification of the globin gene superfamily in vertebrates. Mol Biol Evol 2011; 29:303-12. [PMID: 21965344 DOI: 10.1093/molbev/msr207] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
It has been hypothesized that two successive rounds of whole-genome duplication (WGD) in the stem lineage of vertebrates provided genetic raw materials for the evolutionary innovation of many vertebrate-specific features. However, it has seldom been possible to trace such innovations to specific functional differences between paralogous gene products that derive from a WGD event. Here, we report genomic evidence for a direct link between WGD and key physiological innovations in the vertebrate oxygen transport system. Specifically, we demonstrate that key globin proteins that evolved specialized functions in different aspects of oxidative metabolism (hemoglobin, myoglobin, and cytoglobin) represent paralogous products of two WGD events in the vertebrate common ancestor. Analysis of conserved macrosynteny between the genomes of vertebrates and amphioxus (subphylum Cephalochordata) revealed that homologous chromosomal segments defined by myoglobin + globin-E, cytoglobin, and the α-globin gene cluster each descend from the same linkage group in the reconstructed proto-karyotype of the chordate common ancestor. The physiological division of labor between the oxygen transport function of hemoglobin and the oxygen storage function of myoglobin played a pivotal role in the evolution of aerobic energy metabolism, supporting the hypothesis that WGDs helped fuel key innovations in vertebrate evolution.
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Braasch I, Brunet F, Volff JN, Schartl M. Pigmentation pathway evolution after whole-genome duplication in fish. Genome Biol Evol 2009; 1:479-93. [PMID: 20333216 PMCID: PMC2839281 DOI: 10.1093/gbe/evp050] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2009] [Indexed: 12/29/2022] Open
Abstract
Whole-genome duplications (WGDs) have occurred repeatedly in the vertebrate
lineage, but their evolutionary significance for phenotypic evolution remains
elusive. Here, we have investigated the impact of the fish-specific genome
duplication (FSGD) on the evolution of pigmentation pathways in teleost fishes.
Pigmentation and color patterning are among the most diverse traits in teleosts,
and their pigmentary system is the most complex of all vertebrate groups. Using a comparative genomic approach including phylogenetic and synteny analyses,
the evolution of 128 vertebrate pigmentation genes in five teleost genomes
following the FSGD has been reconstructed. We show that pigmentation genes have
been preferentially retained in duplicate after the FSGD, so that teleosts have
30% more pigmentation genes compared with tetrapods. This is significantly
higher than genome-wide estimates of FSGD gene duplicate retention in teleosts.
Large parts of the melanocyte regulatory network have been retained in two
copies after the FSGD. Duplicated pigmentation genes follow general evolutionary
patterns such as the preservation of protein complex stoichiometries and the
overrepresentation of developmental genes among retained duplicates. These
results suggest that the FSGD has made an important contribution to the
evolution of teleost-specific features of pigmentation, which include novel
pigment cell types or the division of existing pigment cell types into distinct
subtypes. Furthermore, we have observed species-specific differences in
duplicate retention and evolution that might contribute to pigmentary diversity
among teleosts. Our study therefore strongly supports the hypothesis that WGDs have promoted the
increase of complexity and diversity during vertebrate phenotypic evolution.
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Affiliation(s)
- Ingo Braasch
- Physiological Chemistry I, University of Würzburg, Biozentrum, Würzburg, Germany.
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19
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Koussoulakou DS, Margaritis LH, Koussoulakos SL. A curriculum vitae of teeth: evolution, generation, regeneration. Int J Biol Sci 2009; 5:226-43. [PMID: 19266065 PMCID: PMC2651620 DOI: 10.7150/ijbs.5.226] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 02/21/2009] [Indexed: 12/28/2022] Open
Abstract
The ancestor of recent vertebrate teeth was a tooth-like structure on the outer body surface of jawless fishes. Over the course of 500,000,000 years of evolution, many of those structures migrated into the mouth cavity. In addition, the total number of teeth per dentition generally decreased and teeth morphological complexity increased. Teeth form mainly on the jaws within the mouth cavity through mutual, delicate interactions between dental epithelium and oral ectomesenchyme. These interactions involve spatially restricted expression of several, teeth-related genes and the secretion of various transcription and signaling factors. Congenital disturbances in tooth formation, acquired dental diseases and odontogenic tumors affect millions of people and rank human oral pathology as the second most frequent clinical problem. On the basis of substantial experimental evidence and advances in bioengineering, many scientists strongly believe that a deep knowledge of the evolutionary relationships and the cellular and molecular mechanisms regulating the morphogenesis of a given tooth in its natural position, in vivo, will be useful in the near future to prevent and treat teeth pathologies and malformations and for in vitro and in vivo teeth tissue regeneration.
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Affiliation(s)
- Despina S Koussoulakou
- University of Athens, Faculty of Biology, Department of Cell Biology and Biophysics, Athens, Greece
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20
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Braasch I, Volff JN, Schartl M. The endothelin system: evolution of vertebrate-specific ligand-receptor interactions by three rounds of genome duplication. Mol Biol Evol 2009; 26:783-99. [PMID: 19174480 DOI: 10.1093/molbev/msp015] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Morphological innovations like the acquisition of the neural crest as well as gene family expansions by genome duplication are considered as major leaps in the evolution of the vertebrate lineage. Using comparative genomic analyses, we have reconstructed the evolutionary history of the endothelin system, a signaling pathway consisting of endothelin ligands and their G protein-coupled receptors. The endothelin system plays a key role in cardiovascular regulation as well as in the development of diverse neural crest derivatives like pigment cells and craniofacial bone structures, which are hot spots of diversity in vertebrates. However, little is known about the origin and evolution of the endothelin system in the vertebrate lineage. We show that the endothelin core system, that is, endothelin ligands (Edn) and their receptors (Ednr), is a vertebrate-specific innovation. The components of the endothelin core system in modern vertebrate genomes date back to single genes that have been duplicated during whole-genome duplication events. After two rounds of genome duplication during early vertebrate evolution, the endothelin system of an ancestral gnathostome consisted of four ligand and four receptor genes. The previously unknown fourth endothelin ligand Edn4 has been kept in teleost fish but lost in tetrapods. Bony vertebrates generally possess three receptor genes, EdnrA, EdnrB1, and EdnrB2. EdnrB2 has been lost secondarily in the mammalian lineage from a chromosome that gave rise to the sex chromosomes in therians (marsupials and placentals). The endothelin system of fishes was further expanded by a fish-specific genome duplication and duplicated edn2, edn3, ednrA, and ednrB1 genes have been retained in teleost fishes. Functional divergence analyses suppose that following each round of genome duplication, coevolution of ligands and their binding regions in the receptors has occurred, adjusting the endothelin signaling system to the increase of possible ligand-receptor interactions. Furthermore, duplications of genes involved in the endothelin system are associated with functional specialization for the development of particular neural crest derivatives. Our results support an important role for newly emerging ligands and receptors as components of signaling pathways and their expansion through genome duplications in the evolution of the vertebrate neural crest.
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Affiliation(s)
- Ingo Braasch
- University of Würzburg, Biozentrum, Physiological Chemistry I, Germany.
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21
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Abstract
The Hedgehog (Hh) family of proteins control cell growth, survival, and fate, and pattern almost every aspect of the vertebrate body plan. The use of a single morphogen for such a wide variety of functions is possible because cellular responses to Hh depend on the type of responding cell, the dose of Hh received, and the time cells are exposed to Hh. The Hh gradient is shaped by several proteins that are specifically required for Hh processing, secretion, and transport through tissues. The mechanism of cellular response, in turn, incorporates multiple feedback loops that fine-tune the level of signal sensed by the responding cells. Germline mutations that subtly affect Hh pathway activity are associated with developmental disorders, whereas somatic mutations activating the pathway have been linked to multiple forms of human cancer. This review focuses broadly on our current understanding of Hh signaling, from mechanisms of action to cellular and developmental functions. In addition, we review the role of Hh in the pathogenesis of human disease and the possibilities for therapeutic intervention.
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Affiliation(s)
- Markku Varjosalo
- Department of Molecular Medicine, National Public Health Institute (KTL), and Genome-Scale Biology Program, Biomedicum Helsinki, Institute of Biomedicine and High Throughput Center, Faculty of Medicine, University of Helsinki, Helsinki FI-00014, Finland
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Takahashi M, Osumi N. Expression study of cadherin7 and cadherin20 in the embryonic and adult rat central nervous system. BMC DEVELOPMENTAL BIOLOGY 2008; 8:87. [PMID: 18801203 PMCID: PMC2564927 DOI: 10.1186/1471-213x-8-87] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 09/19/2008] [Indexed: 01/18/2023]
Abstract
BACKGROUND Vertebrate classic cadherins are divided into type I and type II subtypes, which are individually expressed in brain subdivisions (e.g., prosomeres, rhombomeres, and progenitor domains) and in specific neuronal circuits in region-specific manners. We reported previously the expression of cadherin19 (cad19) in Schwann cell precursors. Cad19 is a type II classic cadherin closely clustered on a chromosome with cad7 and cad20. The expression patterns of cad7 and cad20 have been reported previously in chick embryo but not in the developing and adult central nervous system of mammals. In this study, we identified rat cad7 and cad20 and analyzed their expression patterns in embryonic and adult rat brains. RESULTS Rat cad7 protein showed 92% similarity to chick cad7, while rat cad20 protein had 76% similarity to Xenopus F-cadherin. Rat cad7 mRNA was initially expressed in the anterior neural plate including presumptive forebrain and midbrain regions, and then accumulated in cells of the dorsal neural tube and in rhombomere boundary cells of the hindbrain. Expression of rat cad20 mRNA was specifically localized in the anterior neural region and rhombomere 2 in the early neural plate, and later in longitudinally defined ventral cells of the hindbrain. The expression boundaries of cad7 and cad20 corresponded to those of region-specific transcription factors such as Six3, Irx3 and Otx2 in the neural plate, and Dbx2 and Gsh1 in the hindbrain. At later stages, the expression of cad7 and cad20 disappeared from neuroepithelial cells in the hindbrain, and was almost restricted to postmitotic cells, e.g. somatic motor neurons and precerebellar neurons. These results emphasized the diversity of cad7 and cad20 expression patterns in different vertebrate species, i.e. birds and rodents. CONCLUSION Taken together, our findings suggest that the expression of cad7 and cad20 demarcates the compartments, boundaries, progenitor domains, specific nuclei and specific neural circuits during mammalian brain development.
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Affiliation(s)
- Masanori Takahashi
- Division of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Noriko Osumi
- Division of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- The Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 4-1-8, Honmachi, Kawaguchi, 332-0012, Japan
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23
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Abstract
Many of the features that distinguish the vertebrates from other chordates are derived from the neural crest, and it has long been argued that the emergence of this multipotent embryonic population was a key innovation underpinning vertebrate evolution. More recently, however, a number of studies have suggested that the evolution of the neural crest was less sudden than previously believed. This has exposed the fact that neural crest, as evidenced by its repertoire of derivative cell types, has evolved through vertebrate evolution. In this light, attempts to derive a typological definition of neural crest, in terms of molecular signatures or networks, are unfounded. We propose a less restrictive, embryological definition of this cell type that facilitates, rather than precludes, investigating the evolution of neural crest. While the evolutionary origin of neural crest has attracted much attention, its subsequent evolution has received almost no attention and yet it is more readily open to experimental investigation and has greater relevance to understanding vertebrate evolution. Finally, we provide a brief outline of how the evolutionary emergence of neural crest potentiality may have proceeded, and how it may be investigated.
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Mise T, Iijima M, Inohaya K, Kudo A, Wada H. Function of Pax1 and Pax9 in the sclerotome of medaka fish. Genesis 2008; 46:185-92. [PMID: 18395830 DOI: 10.1002/dvg.20381] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We examined the expression and functions of Pax1 and Pax9 in a teleost fish, the medaka Oryzias latipes. While Pax1 and Pax9 show distinct expression in the sclerotome in amniotes, we could not detect the differential expression of Pax1 and Pax9 in the developing sclerotome of the medaka. Furthermore, unlike the mouse, in which Pax1 is essential for development of the vertebral body, and where the neural arch is formed independent of either Pax1 or Pax9, our morpholino knockdown experiments revealed that both Pax1 and Pax9 are indispensable for the development of the vertebral body and neural arch. Therefore, we conclude that after gene duplication, Pax1 and Pax9 subfunctionalize their roles in the sclerotome independently in teleosts and amniotes. In Stage-30 embryo, Pax9 was strongly expressed in the posterior mesoderm, as was also observed for mouse Pax9. Since this expression was not detected for Pax1 in the mouse or fish, this new expression in the posterior mesoderm likely evolved in Pax9 of ancestral vertebrates after gene duplication. Two-month-old fish injected with Pax9 morpholino oligonucleotide showed abnormal morphology in the tail hypural skeletal element, which may have been related to this expression.
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Affiliation(s)
- Takeshi Mise
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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25
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Okada K, Asai K. Retention of genes involved in the adenohypophysis-mediated endocrine system in early vertebrates. Gene 2008; 412:71-83. [PMID: 18302976 DOI: 10.1016/j.gene.2008.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 01/15/2008] [Accepted: 01/16/2008] [Indexed: 10/22/2022]
Abstract
The adenohypophysis of vertebrates receives peptide hormones from the hypothalamus and secretes hormones that regulate diverse physiologic processes in peripheral organs. The adenohypophysis-mediated endocrine system is widely conserved across vertebrates but not invertebrates. Phylogenetic analysis indicates that the emergence of this system coincided with two rounds of whole-genome duplication (2R-WGD) in early vertebrates, but direct evidence linking these events has been unavailable. We detected all human paralogons (series of paralogous regions) formed in early vertebrates as traces of 2R-WGD, and examined the relationship between 2R-WGD and the evolution of genes essential to the adenohypophysis-mediated endocrine system. Regarding genes encoding transcription factors (TFs) involved in the terminal differentiation into hormone-secreting cells in adenohypophyseal development, we showed that most pairs of these genes and their paralogs were part of paralogons. In addition, our analysis also indicated that most of the paralog pairs in families of adenohypophyseal hormones and their receptors were part of paralogons. These results suggest that 2R-WGD played an important role in generating genes encoding adenohypophyseal TFs, hormones, and their receptors for increasing the diversification of hormone repertoire in the adenohypophysis-mediated endocrine system of vertebrates.
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Affiliation(s)
- Kinya Okada
- Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
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