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Isabella AJ, Moens CB. Development and regeneration of the vagus nerve. Semin Cell Dev Biol 2024; 156:219-227. [PMID: 37537116 PMCID: PMC10830892 DOI: 10.1016/j.semcdb.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 08/05/2023]
Abstract
The vagus nerve, with its myriad constituent axon branches and innervation targets, has long been a model of anatomical complexity in the nervous system. The branched architecture of the vagus nerve is now appreciated to be highly organized around the topographic and/or molecular identities of the neurons that innervate each target tissue. However, we are only just beginning to understand the developmental mechanisms by which heterogeneous vagus neuron identity is specified, patterned, and used to guide the axons of particular neurons to particular targets. Here, we summarize our current understanding of the complex topographic and molecular organization of the vagus nerve, the developmental basis of neuron specification and patterned axon guidance that supports this organization, and the regenerative mechanisms that promote, or inhibit, the restoration of vagus nerve organization after nerve damage. Finally, we highlight key unanswered questions in these areas and discuss potential strategies to address these questions.
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Affiliation(s)
- Adam J Isabella
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Cecilia B Moens
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
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2
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Itoh T, Takeuchi M, Sakagami M, Asakawa K, Sumiyama K, Kawakami K, Shimizu T, Hibi M. Gsx2 is required for specification of neurons in the inferior olivary nuclei from Ptf1a-expressing neural progenitors in zebrafish. Development 2020; 147:dev.190603. [PMID: 32928905 DOI: 10.1242/dev.190603] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 09/03/2020] [Indexed: 11/20/2022]
Abstract
Neurons in the inferior olivary nuclei (IO neurons) send climbing fibers to Purkinje cells to elicit functions of the cerebellum. IO neurons and Purkinje cells are derived from neural progenitors expressing the proneural gene ptf1a In this study, we found that the homeobox gene gsx2 was co-expressed with ptf1a in IO progenitors in zebrafish. Both gsx2 and ptf1a zebrafish mutants showed a strong reduction or loss of IO neurons. The expression of ptf1a was not affected in gsx2 mutants, and vice versa. In IO progenitors, the ptf1a mutation increased apoptosis whereas the gsx2 mutation did not, suggesting that ptf1a and gsx2 are regulated independently of each other and have distinct roles. The fibroblast growth factors (Fgf) 3 and 8a, and retinoic acid signals negatively and positively, respectively, regulated gsx2 expression and thereby the development of IO neurons. mafba and Hox genes are at least partly involved in the Fgf- and retinoic acid-dependent regulation of IO neuronal development. Our results indicate that gsx2 mediates the rostro-caudal positional signals to specify the identity of IO neurons from ptf1a-expressing neural progenitors.
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Affiliation(s)
- Tsubasa Itoh
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Miki Takeuchi
- Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Marina Sakagami
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan
| | - Kazuhide Asakawa
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Kenta Sumiyama
- RIKEN Center for Biosystems Dynamics Research (BDR), Suita, Osaka 565-0871, Japan
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Takashi Shimizu
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan.,Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Masahiko Hibi
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8602, Japan .,Bioscience and Biotechnology Center, Nagoya University, Furo, Chikusa, Nagoya, Aichi 464-8601, Japan
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3
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The Cdx transcription factors and retinoic acid play parallel roles in antero-posterior position of the pectoral fin field during gastrulation. Mech Dev 2020; 164:103644. [PMID: 32911082 DOI: 10.1016/j.mod.2020.103644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 12/27/2022]
Abstract
The molecular regulators that determine the precise position of the vertebrate limb along the anterio-posterior axis have not been identified. One model suggests that a combination of hox genes in the lateral plate mesoderm (LPM) promotes formation of the limb field, however redundancy among duplicated paralogs has made this model difficult to confirm. In this study, we identify an optimal window during mid-gastrulation stages when transient mis-regulation of retinoic acid signaling or the caudal related transcription factor, Cdx4, both known regulators of hox genes, can alter the position of the pectoral fin field. We show that increased levels of either RA or Cdx4 during mid-gastrulation are sufficient to rostrally shift the position of the pectoral fin field at the expense of surrounding gene expression in the anterior lateral plate mesoderm (aLPM). Alternatively, embryos deficient for both Cdx4 and Cdx1a (Cdx-deficient) form pectoral fins that are shifted towards the posterior and reveal an additional effect on size of the pectoral fin buds. Prior to formation of the pectoral fin buds, the fin field in Cdx-deficient embryos is visibly expanded into the posterior LPM (pLPM) region at the expense of surrounding gene expression. The effects on gene expression immediately post-gastrulation and during somitogenesis support a model where RA and Cdx4 act in parallel to regulate the position of the pectoral fin. Our transient method is a potentially useful model for studying the mechanisms of limb positioning along the AP axis.
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DeLaurier A. Evolution and development of the fish jaw skeleton. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2018; 8:e337. [PMID: 30378758 DOI: 10.1002/wdev.337] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/18/2022]
Abstract
The evolution of the jaw represents a key innovation in driving the diversification of vertebrate body plans and behavior. The pharyngeal apparatus originated as gill bars separated by slits in chordate ancestors to vertebrates. Later, with the acquisition of neural crest, pharyngeal arches gave rise to branchial basket cartilages in jawless vertebrates (agnathans), and later bone and cartilage of the jaw, jaw support, and gills of jawed vertebrates (gnathostomes). Major events in the evolution of jaw structure from agnathans to gnathostomes include axial regionalization of pharyngeal elements and formation of a jaw joint. Hox genes specify the anterior-posterior identity of arches, and edn1, dlx, hand2, Jag1b-Notch2 signaling, and Nr2f factors specify dorsal-ventral identity. The formation of a jaw joint, an important step in the transition from an un-jointed pharynx in agnathans to a hinged jaw in gnathostomes involves interaction between nkx3.2, hand2, and barx1 factors. Major events in jaw patterning between fishes and reptiles include changes to elements of the second pharyngeal arch, including a loss of opercular and branchiostegal ray bones and transformation of the hyomandibula into the stapes. Further changes occurred between reptiles and mammals, including the transformation of the articular and quadrate elements of the jaw joint into the malleus and incus of the middle ear. Fossils of transitional jaw phenotypes can be analyzed from a developmental perspective, and there exists potential to use genetic manipulation techniques in extant taxa to test hypotheses about the evolution of jaw patterning in ancient vertebrates. This article is categorized under: Comparative Development and Evolution > Evolutionary Novelties Early Embryonic Development > Development to the Basic Body Plan Comparative Development and Evolution > Body Plan Evolution.
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Affiliation(s)
- April DeLaurier
- Department of Biology and Geology, University of South Carolina Aiken, Aiken, South Carolina
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5
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Rinkwitz S, Geng FS, Manning E, Suster M, Kawakami K, Becker TS. BAC transgenic zebrafish reveal hypothalamic enhancer activity around obesity associated SNP rs9939609 within the human FTO gene. Genesis 2015; 53:640-51. [PMID: 26271004 PMCID: PMC5054831 DOI: 10.1002/dvg.22884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/05/2015] [Accepted: 08/12/2015] [Indexed: 12/22/2022]
Abstract
Single Nucleotide Polymorphisms in FTO intron 1 have been associated with obesity risk, leading to the hypothesis that FTO is the obesity‐related gene. However, other studies have shown that the FTO gene is part of the regulatory domain of the neighboring IRX3 gene and that enhancers in FTO intron 1 regulate IRX3. While Irx3 activity was shown to be necessary in the hypothalamus for the metabolic function of Irx3 in mouse, no enhancers with hypothalamic activity have been demonstrated in the risk‐associated region within FTO. In order to identify potential enhancers at the human FTO locus in vivo, we tested regulatory activity in FTO intron 1 using BAC transgenesis in zebrafish. A minimal gata2 promoter‐GFP cassette was inserted 1.3 kb upstream of the obesity associated SNP rs9939609 in a human FTO BAC plasmid. In addition to the previously identified expression domains in notochord and kidney, human FTO BAC:GFP transgenic zebrafish larvae expressed GFP in the ventral posterior tuberculum, the posterior hypothalamus and the anterior brainstem, which are also expression domains of zebrafish irx3a. In contrast, an in‐frame insertion of a GFP cassette at the FTO start codon resulted in weak ubiquitous GFP expression indicating that the promoter of FTO does likely not react to enhancers located in the obesity risk‐associated region. genesis 53:640–651, 2015. © 2015 The Authors. genesis Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Silke Rinkwitz
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.,Department of Physiology, School of Medicine, University of Sydney, Australia
| | - Fan-Suo Geng
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia
| | - Elizabeth Manning
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia
| | | | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Thomas S Becker
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.,Department of Physiology, School of Medicine, University of Sydney, Australia
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6
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Copy number variants in patients with intellectual disability affect the regulation of ARX transcription factor gene. Hum Genet 2015; 134:1163-82. [PMID: 26337422 DOI: 10.1007/s00439-015-1594-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 08/16/2015] [Indexed: 10/23/2022]
Abstract
Protein-coding mutations in the transcription factor-encoding gene ARX cause various forms of intellectual disability (ID) and epilepsy. In contrast, variations in surrounding non-coding sequences are correlated with milder forms of non-syndromic ID and autism and had suggested the importance of ARX gene regulation in the etiology of these disorders. We compile data on several novel and some already identified patients with or without ID that carry duplications of ARX genomic region and consider likely genetic mechanisms underlying the neurodevelopmental defects. We establish the long-range regulatory domain of ARX and identify its brain region-specific autoregulation. We conclude that neurodevelopmental disturbances in the patients may not simply arise from increased dosage due to ARX duplication. This is further exemplified by a small duplication involving a non-functional ARX copy, but with duplicated enhancers. ARX enhancers are located within a 504-kb region and regulate expression specifically in the forebrain in developing and adult zebrafish. Transgenic enhancer-reporter lines were used as in vivo tools to delineate a brain region-specific negative and positive autoregulation of ARX. We find autorepression of ARX in the telencephalon and autoactivation in the ventral thalamus. Fluorescently labeled brain regions in the transgenic lines facilitated the identification of neuronal outgrowth and pathfinding disturbances in the ventral thalamus and telencephalon that occur when arxa dosage is diminished. In summary, we have established a model for how breakpoints in long-range gene regulation alter the expression levels of a target gene brain region-specifically, and how this can cause subtle neuronal phenotypes relating to the etiology of associated neuropsychiatric disease.
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7
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Takeuchi M, Matsuda K, Yamaguchi S, Asakawa K, Miyasaka N, Lal P, Yoshihara Y, Koga A, Kawakami K, Shimizu T, Hibi M. Establishment of Gal4 transgenic zebrafish lines for analysis of development of cerebellar neural circuitry. Dev Biol 2014; 397:1-17. [PMID: 25300581 DOI: 10.1016/j.ydbio.2014.09.030] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/03/2014] [Accepted: 09/26/2014] [Indexed: 02/02/2023]
Abstract
The cerebellum is involved in some forms of motor coordination and motor learning. Here we isolated transgenic (Tg) zebrafish lines that express a modified version of Gal4-VP16 (GFF) in the cerebellar neural circuits: granule, Purkinje, or eurydendroid cells, Bergmann glia, or the neurons in the inferior olive nuclei (IO) which send climbing fibers to Purkinje cells, with the transposon Tol2 system. By combining GFF lines with Tg lines carrying a reporter gene located downstream of Gal4 binding sequences (upstream activating sequence: UAS), we investigated the anatomy and developmental processes of the cerebellar neural circuitry. Combining an IO-specific Gal4 line with a UAS reporter line expressing the photoconvertible fluorescent protein Kaede demonstrated the contralateral projections of climbing fibers. Combining a granule cell-specific Gal4 line with a UAS reporter line expressing wheat germ agglutinin (WGA) confirmed direct and/or indirect connections of granule cells with Purkinje cells, eurydendroid cells, and IO neurons in zebrafish. Time-lapse analysis of a granule cell-specific Gal4 line revealed initial random movements and ventral migration of granule cell nuclei. Transgenesis of a reporter gene with another transposon Tol1 system visualized neuronal structure at a single cell resolution. Our findings indicate the usefulness of these zebrafish Gal4 Tg lines for studying the development and function of cerebellar neural circuits.
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Affiliation(s)
- Miki Takeuchi
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Koji Matsuda
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Shingo Yamaguchi
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Kazuhide Asakawa
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | | | - Pradeep Lal
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | | | - Akihiko Koga
- Primate Research Institute, Kyoto University, Inuyama 464-8506, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Takashi Shimizu
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Masahiko Hibi
- Laboratory of Organogenesis and Organ Function, Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan.
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8
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Saxena A, Bronner ME. A novel HoxB cluster protein expressed in the hindbrain and pharyngeal arches. Genesis 2014; 52:858-63. [PMID: 25137177 DOI: 10.1002/dvg.22806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 08/11/2014] [Accepted: 08/13/2014] [Indexed: 11/11/2022]
Abstract
We describe a novel zebrafish line that fluorescently tags a previously unknown protein, CT74a, allowing us to follow its endogenous expression in real time and at subcellular resolution in live embryos. Our results showed that CT74a-Citrine fusion protein is expressed in the developing pharyngeal arches, hindbrain, and fin buds in a pattern highly reminiscent of transcription factors belonging to anterior Hox gene families, including expression in a subset of neuronal nuclei. Consistent with this, splinkerette-PCR revealed that CT74a-Citrine's genomic integration is within the HoxB region, and 3' RACE demonstrated that its downstream coding sequence has no recognizable homology. Thus, CT74a is a previously unknown protein located within the HoxB cluster adjacent to Hoxb4a and is expressed in a Hoxb4a-like pattern.
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Affiliation(s)
- Ankur Saxena
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, 91125
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9
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Hibi M, Shimizu T. Development of the cerebellum and cerebellar neural circuits. Dev Neurobiol 2012; 72:282-301. [DOI: 10.1002/dneu.20875] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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Atypical protein kinase C regulates primary dendrite specification of cerebellar Purkinje cells by localizing Golgi apparatus. J Neurosci 2011; 30:16983-92. [PMID: 21159968 DOI: 10.1523/jneurosci.3352-10.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neurons have highly polarized structures that determine what parts of the soma elaborate the axon and dendrites. However, little is known about the mechanisms that establish neuronal polarity in vivo. Cerebellar Purkinje cells extend a single primary dendrite from the soma that ramifies into a highly branched dendritic arbor. We used the zebrafish cerebellum to investigate the mechanisms by which Purkinje cells acquire these characteristics. To examine dendritic morphogenesis in individual Purkinje cells, we marked the cell membrane using a Purkinje cell-specific promoter to drive membrane-targeted fluorescent proteins. We found that zebrafish Purkinje cells initially extend multiple neurites from the soma and subsequently retract all but one, which becomes the primary dendrite. In addition, the Golgi apparatus specifically locates to the root of the primary dendrite, and its localization is already established in immature Purkinje cells that have multiple neurites. Inhibiting secretory trafficking through the Golgi apparatus reduces dendritic growth, suggesting that the Golgi apparatus is involved in the dendritic morphogenesis. We also demonstrated that in a mutant of an atypical protein kinase C (aPKC), Prkci, Purkinje cells retain multiple primary dendrites and show disrupted localization of the Golgi apparatus. Furthermore, a mosaic inhibition of Prkci in Purkinje cells recapitulates the aPKC mutant phenotype. These results suggest that the aPKC cell autonomously controls the Golgi localization and thereby regulates the specification of the primary dendrite of Purkinje cells.
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11
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Rinkwitz S, Mourrain P, Becker TS. Zebrafish: an integrative system for neurogenomics and neurosciences. Prog Neurobiol 2010; 93:231-43. [PMID: 21130139 DOI: 10.1016/j.pneurobio.2010.11.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 11/08/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
Abstract
Rapid technological advances over the past decade have moved us closer to a high throughput molecular approach to neurobiology, where we see the merging of neurogenetics, genomics, physiology, imaging and pharmacology. This is the case more in zebrafish than in any other model organism commonly used. Recent improvements in the generation of transgenic zebrafish now allow genetic manipulation and live imaging of neuronal development and function in early embryonic, larval, and adult animals. The sequenced zebrafish genome and comparative genomics give unprecedented insights into genome evolution and its relation to genome structure and function. There is now information on embryonic and larval expression of over 12,000 genes and just under 1000 mutant phenotypes. We review the remarkable similarity of the zebrafish genetic blueprint for the nervous system to that of mammals and assess recent technological advances that make the zebrafish a model of choice for elucidating the development and function of neuronal circuitry, transgene-based neuroanatomy, and small molecule neuropharmacology.
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Affiliation(s)
- Silke Rinkwitz
- Brain and Mind Research Institute, Sydney Medical School, University of Sydney, 100 Mallett St., Camperdown, NSW 2050, Australia
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12
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Ancestry of motor innervation to pectoral fin and forelimb. Nat Commun 2010; 1:49. [PMID: 20975699 PMCID: PMC2963806 DOI: 10.1038/ncomms1045] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 06/30/2010] [Indexed: 02/03/2023] Open
Abstract
Motor innervation to the tetrapod forelimb and fish pectoral fin is assumed to share a conserved spinal cord origin, despite major structural and functional innovations of the appendage during the vertebrate water-to-land transition. In this paper, we present anatomical and embryological evidence showing that pectoral motoneurons also originate in the hindbrain among ray-finned fish. New and previous data for lobe-finned fish, a group that includes tetrapods, and more basal cartilaginous fish showed pectoral innervation that was consistent with a hindbrain-spinal origin of motoneurons. Together, these findings support a hindbrain–spinal phenotype as the ancestral vertebrate condition that originated as a postural adaptation for pectoral control of head orientation. A phylogenetic analysis indicated that Hox gene modules were shared in fish and tetrapod pectoral systems. We propose that evolutionary shifts in Hox gene expression along the body axis provided a transcriptional mechanism allowing eventual decoupling of pectoral motoneurons from the hindbrain much like their target appendage gained independence from the head. It was previously thought that the nerves in the pectoral fin of fish came solely from the spinal cord. Here, motoneurons in ray-finned fish are shown to also originate from the hindbrain, demonstrating that innervation was from both the hindbrain and the spinal cord in ancesteral vertebrates.
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13
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Cis-regulatory characterization of sequence conservation surrounding the Hox4 genes. Dev Biol 2010; 340:269-82. [PMID: 20144609 DOI: 10.1016/j.ydbio.2010.01.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 01/17/2010] [Accepted: 01/30/2010] [Indexed: 01/30/2023]
Abstract
Hox genes are key regulators of anterior-posterior axis patterning and have a major role in hindbrain development. The zebrafish Hox4 paralogs have strong overlapping activities in hindbrain rhombomeres 7 and 8, in the spinal cord and in the pharyngeal arches. With the aim to predict enhancers that act on the hoxa4a, hoxb4a, hoxc4a and hoxd4a genes, we used sequence conservation around the Hox4 genes to analyze all fish:human conserved non-coding sequences by reporter assays in stable zebrafish transgenesis. Thirty-four elements were functionally tested in GFP reporter gene constructs and more than 100 F1 lines were analyzed to establish a correlation between sequence conservation and cis-regulatory function, constituting a catalog of Hox4 CNEs. Sixteen tissue-specific enhancers could be identified. Multiple alignments of the CNEs revealed paralogous cis-regulatory sequences, however, the CNE sequence similarities were found not to correlate with tissue specificity. To identify ancestral enhancers that direct Hox4 gene activity, genome sequence alignments of mammals, teleosts, horn shark and the cephalochordate amphioxus, which is the most basal extant chordate possessing a single prototypical Hox cluster, were performed. Three elements were identified and two of them exhibited regulatory activity in transgenic zebrafish, however revealing no specificity. Our data show that the approach to identify cis-regulatory sequences by genome sequence alignments and subsequent testing in zebrafish transgenesis can be used to define enhancers within the Hox clusters and that these have significantly diverged in their function during evolution.
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14
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Ma LH, Punnamoottil B, Rinkwitz S, Baker R. Mosaic hoxb4a neuronal pleiotropism in zebrafish caudal hindbrain. PLoS One 2009; 4:e5944. [PMID: 19536294 PMCID: PMC2693931 DOI: 10.1371/journal.pone.0005944] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Accepted: 05/12/2009] [Indexed: 12/26/2022] Open
Abstract
To better understand how individual genes and experience influence behavior, the role of a single homeotic unit, hoxb4a, was comprehensively analyzed in vivo by clonal and retrograde fluorescent labeling of caudal hindbrain neurons in a zebrafish enhancer-trap YFP line. A quantitative spatiotemporal neuronal atlas showed hoxb4a activity to be highly variable and mosaic in rhombomere 7–8 reticular, motoneuronal and precerebellar nuclei with expression decreasing differentially in all subgroups through juvenile stages. The extensive Hox mosaicism and widespread pleiotropism demonstrate that the same transcriptional protein plays a role in the development of circuits that drive behaviors from autonomic through motor function including cerebellar regulation. We propose that the continuous presence of hoxb4a positive neurons may provide a developmental plasticity for behavior-specific circuits to accommodate experience- and growth-related changes. Hence, the ubiquitous hoxb4a pleitropism and modularity likely offer an adaptable transcriptional element for circuit modification during both growth and evolution.
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Affiliation(s)
- Leung-Hang Ma
- Department of Physiology and Neuroscience, New York University Medical Center, New York, New York, United States of America
| | - Beena Punnamoottil
- Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia
| | - Silke Rinkwitz
- Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia
| | - Robert Baker
- Department of Physiology and Neuroscience, New York University Medical Center, New York, New York, United States of America
- * E-mail:
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15
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Bae YK, Kani S, Shimizu T, Tanabe K, Nojima H, Kimura Y, Higashijima SI, Hibi M. Anatomy of zebrafish cerebellum and screen for mutations affecting its development. Dev Biol 2009; 330:406-26. [PMID: 19371731 DOI: 10.1016/j.ydbio.2009.04.013] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 04/06/2009] [Accepted: 04/07/2009] [Indexed: 01/11/2023]
Abstract
The cerebellum is important for the integration of sensory perception and motor control, but its structure has mostly been studied in mammals. Here, we describe the cell types and neural tracts of the adult zebrafish cerebellum using molecular markers and transgenic lines. Cerebellar neurons are categorized to two major groups: GABAergic and glutamatergic neurons. The Purkinje cells, which are GABAergic neurons, express parvalbumin7, carbonic anhydrase 8, and aldolase C like (zebrin II). The glutamatergic neurons are vglut1(+) granule cells and vglut2(high) cells, which receive Purkinje cell inputs; some vglut2(high) cells are eurydendroid cells, which are equivalent to the mammalian deep cerebellar nuclei. We found olig2(+) neurons in the adult cerebellum and ascertained that at least some of them are eurydendroid cells. We identified markers for climbing and mossy afferent fibers, efferent fibers, and parallel fibers from granule cells. Furthermore, we found that the cerebellum-like structures in the optic tectum and antero-dorsal hindbrain show similar Parvalbumin7 and Vglut1 expression profiles as the cerebellum. The differentiation of GABAergic and glutamatergic neurons begins 3 days post-fertilization (dpf), and layers are first detectable 5 dpf. Using anti-Parvalbumin7 and Vglut1 antibodies to label Purkinje cells and granule cell axons, respectively, we screened for mutations affecting cerebellar neuronal development and the formation of neural tracts. Our data provide a platform for future studies of zebrafish cerebellar development.
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Affiliation(s)
- Young-Ki Bae
- Laboratory for Vertebrate Axis Formation, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
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Recent Papers on Zebrafish and Other Aquarium Fish Models. Zebrafish 2008. [DOI: 10.1089/zeb.2008.9987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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