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Jurynec MJ, Bai X, Bisgrove BW, Jackson H, Nechiporuk A, Palu RAS, Grunwald HA, Su YC, Hoshijima K, Yost HJ, Zon LI, Grunwald DJ. The Paf1 complex and P-TEFb have reciprocal and antagonist roles in maintaining multipotent neural crest progenitors. Development 2019; 146:dev.180133. [PMID: 31784460 DOI: 10.1242/dev.180133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 11/21/2019] [Indexed: 01/01/2023]
Abstract
Multipotent progenitor populations are necessary for generating diverse tissue types during embryogenesis. We show the RNA polymerase-associated factor 1 complex (Paf1C) is required to maintain multipotent progenitors of the neural crest (NC) lineage in zebrafish. Mutations affecting each Paf1C component result in near-identical NC phenotypes; alyron mutant embryos carrying a null mutation in paf1 were analyzed in detail. In the absence of zygotic paf1 function, definitive premigratory NC progenitors arise but fail to maintain expression of the sox10 specification gene. The mutant NC progenitors migrate aberrantly and fail to differentiate appropriately. Blood and germ cell progenitor development is affected similarly. Development of mutant NC could be rescued by additional loss of positive transcription elongation factor b (P-TEFb) activity, a key factor in promoting transcription elongation. Consistent with the interpretation that inhibiting/delaying expression of some genes is essential for maintaining progenitors, mutant embryos lacking the CDK9 kinase component of P-TEFb exhibit a surfeit of NC progenitors and their derivatives. We propose Paf1C and P-TEFb act antagonistically to regulate the timing of the expression of genes needed for NC development.
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Affiliation(s)
- Michael J Jurynec
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Xiaoying Bai
- Stem Cell Program and Division of Hematology/Oncology, Children's Hospital and Dana Farber Cancer Institute, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Brent W Bisgrove
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA
| | - Haley Jackson
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Alex Nechiporuk
- Department of Cell and Developmental Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Rebecca A S Palu
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Hannah A Grunwald
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Yi-Chu Su
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA
| | - Kazuyuki Hoshijima
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - H Joseph Yost
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA
| | - Leonard I Zon
- Stem Cell Program and Division of Hematology/Oncology, Children's Hospital and Dana Farber Cancer Institute, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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Erickson T, Morgan CP, Olt J, Hardy K, Busch-Nentwich E, Maeda R, Clemens R, Krey JF, Nechiporuk A, Barr-Gillespie PG, Marcotti W, Nicolson T. Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt). eLife 2017; 6. [PMID: 28534737 PMCID: PMC5462536 DOI: 10.7554/elife.28474] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 05/20/2017] [Indexed: 01/18/2023] Open
Abstract
Transmembrane O-methyltransferase (TOMT/LRTOMT) is responsible for non-syndromic deafness DFNB63. However, the specific defects that lead to hearing loss have not been described. Using a zebrafish model of DFNB63, we show that the auditory and vestibular phenotypes are due to a lack of mechanotransduction (MET) in Tomt-deficient hair cells. GFP-tagged Tomt is enriched in the Golgi of hair cells, suggesting that Tomt might regulate the trafficking of other MET components to the hair bundle. We found that Tmc1/2 proteins are specifically excluded from the hair bundle in tomt mutants, whereas other MET complex proteins can still localize to the bundle. Furthermore, mouse TOMT and TMC1 can directly interact in HEK 293 cells, and this interaction is modulated by His183 in TOMT. Thus, we propose a model of MET complex assembly where Tomt and the Tmcs interact within the secretory pathway to traffic Tmc proteins to the hair bundle. DOI:http://dx.doi.org/10.7554/eLife.28474.001
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Affiliation(s)
- Timothy Erickson
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Clive P Morgan
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Jennifer Olt
- Department of Biomedical Science, University of Sheffield, Sheffield, United States
| | - Katherine Hardy
- Department of Biomedical Science, University of Sheffield, Sheffield, United States
| | | | - Reo Maeda
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Rachel Clemens
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Jocelyn F Krey
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Alex Nechiporuk
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, United States
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, United States
| | - Teresa Nicolson
- Oregon Hearing Research Center and the Vollum Institute, Oregon Health and Science University, Portland, United States
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Abstract
Multicellular rosettes have recently been appreciated as important cellular intermediates that are observed during the formation of diverse organ systems. These rosettes are polarized, transient epithelial structures that sometimes recapitulate the form of the adult organ. Rosette formation has been studied in various developmental contexts, such as in the zebrafish lateral line primordium, the vertebrate pancreas, the Drosophila epithelium and retina, as well as in the adult neural stem cell niche. These studies have revealed that the cytoskeletal rearrangements responsible for rosette formation appear to be conserved. By contrast, the extracellular cues that trigger these rearrangements in vivo are less well understood and are more diverse. Here, we review recent studies of the genetic regulation and cellular transitions involved in rosette formation. We discuss and compare specific models for rosette formation and highlight outstanding questions in the field.
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Affiliation(s)
- Molly J Harding
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR 97239, USA Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR 97239, USA
| | - Hillary F McGraw
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alex Nechiporuk
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR 97239, USA
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Harding MJ, Nechiporuk A. FGF-Ras-MAPK signaling drives apical constriction during zebrafish mechanosensory organ formation. Dev Biol 2011. [DOI: 10.1016/j.ydbio.2011.05.602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mo W, Chen F, Nechiporuk A, Nicolson T. Quantification of vestibular-induced eye movements in zebrafish larvae. BMC Neurosci 2010; 11:110. [PMID: 20815905 PMCID: PMC2941499 DOI: 10.1186/1471-2202-11-110] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 09/03/2010] [Indexed: 11/12/2022] Open
Abstract
Background Vestibular reflexes coordinate movements or sensory input with changes in body or head position. Vestibular-evoked responses that involve the extraocular muscles include the vestibulo-ocular reflex (VOR), a compensatory eye movement to stabilize retinal images. Although an angular VOR attributable to semicircular canal stimulation was reported to be absent in free-swimming zebrafish larvae, recent studies reveal that vestibular-induced eye movements can be evoked in zebrafish larvae by both static tilts and dynamic rotations that tilt the head with respect to gravity. Results We have determined herein the basis of sensitivity of the larval eye movements with respect to vestibular stimulus, developmental stage, and sensory receptors of the inner ear. For our experiments, video recordings of larvae rotated sinusoidally at 0.25 Hz were analyzed to quantitate eye movements under infrared illumination. We observed a robust response that appeared as early as 72 hours post fertilization (hpf), which increased in amplitude over time. Unlike rotation about an earth horizontal axis, rotation about an earth vertical axis at 0.25 Hz did not evoke eye movements. Moreover, vestibular-induced responses were absent in mutant cdh23 larvae and larvae lacking anterior otoliths. Conclusions Our results provide evidence for a functional vestibulo-oculomotor circuit in 72 hpf zebrafish larvae that relies upon sensory input from anterior/utricular otolith organs.
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Affiliation(s)
- Weike Mo
- Howard Hughes Medical Institute, Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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Drerup CM, Kaech S, Banker G, Nechiporuk A. Going rogue: In vivo analysis of axon transport in zebrafish. Dev Biol 2010. [DOI: 10.1016/j.ydbio.2010.05.232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
During development, organ primordia reorganize to form repeated functional units. In zebrafish (Danio rerio), mechanosensory organs called neuromasts are deposited at regular intervals by the migrating posterior lateral line (pLL) primordium. The pLL primordium is organized into polarized rosettes representing proto-neuromasts, each with a central atoh1a-positive focus of mechanosensory precursors. We show that rosettes form cyclically from a progenitor pool at the leading zone of the primordium as neuromasts are deposited from the trailing region. fgf3/10 signals localized to the leading zone are required for rosette formation, atoh1a expression, and primordium migration. We propose that the fibroblast growth factor (FGF) source controls primordium organization, which, in turn, regulates the periodicity of neuromast deposition. This previously unrecognized mechanism may be applicable to understanding segmentation and morphogenesis in other organ systems.
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Affiliation(s)
- Alex Nechiporuk
- University of Washington, School of Medicine, Department of Biological Structure, Seattle, WA 98195-7420, USA.
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Kiehl TR, Nechiporuk A, Figueroa KP, Keating MT, Huynh DP, Pulst SM. Generation and characterization of Sca2 (ataxin-2) knockout mice. Biochem Biophys Res Commun 2006; 339:17-24. [PMID: 16293225 DOI: 10.1016/j.bbrc.2005.10.186] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Accepted: 10/23/2005] [Indexed: 10/25/2022]
Abstract
Ataxin-2, the gene product of the Spinocerebellar Ataxia Type 2 (SCA2) gene, is a protein of unknown function with abundant expression in embryonic and adult tissues. Its interaction with A2BP1/Fox-1, a protein with an RNA recognition motif, suggests involvement of ataxin-2 in mRNA translation or transport. To study the effects of in vivo ataxin-2 function, we generated an ataxin-2 deficient mouse strain. Ataxin-2 deficient mice were viable. Genotypic analysis of litters from mating of heterozygous mice showed segregation distortion with a significant reduction in the birth of Sca-/- females. Detailed macroscopic and microscopic analysis of surviving nullizygous Sca2 knockout mice showed no major histological abnormalities. On a fat-enriched diet, ataxin-2 deficient animals had increased weight gain. Our results demonstrate that ataxin-2, although widely expressed, is not essential in development or during adult survival in the mouse, but leads to adult-onset obesity.
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Affiliation(s)
- Tim-Rasmus Kiehl
- Rose Moss Laboratory for Parkinson and Neurodegenerative Diseases, Burns and Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
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Poss KD, Nechiporuk A, Stringer KF, Lee C, Keating MT. Germ cell aneuploidy in zebrafish with mutations in the mitotic checkpoint gene mps1. Genes Dev 2004; 18:1527-32. [PMID: 15231734 PMCID: PMC443515 DOI: 10.1101/gad.1182604] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Aneuploidy, resulting from chromosome missegregation during meiosis, is a major cause of human infertility and birth defects. However, its molecular basis remains incompletely understood. Here we have identified a spectrum of chromosome anomalies in embryos of zebrafish homozygous for a hypomorphic mutation in Mps1, a kinase required for the mitotic checkpoint. These aneuploidies are caused by meiotic error and result in severe developmental defects. Our results reveal Mps1 as a critical regulator of chromosome number in zebrafish, and demonstrate how slight genetic perturbation of a mitotic checkpoint factor can dramatically reduce the fidelity of chromosome segregation during vertebrate meiosis.
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Affiliation(s)
- Kenneth D Poss
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Nechiporuk A, Poss KD, Johnson SL, Keating MT. Positional cloning of a temperature-sensitive mutant emmental reveals a role for sly1 during cell proliferation in zebrafish fin regeneration. Dev Biol 2003; 258:291-306. [PMID: 12798289 DOI: 10.1016/s0012-1606(03)00129-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Here, we used classical genetics in zebrafish to identify temperature-sensitive mutants in caudal fin regeneration. Gross morphological, histological, and molecular analyses revealed that one of these strains, emmental (emm), failed to form a functional regeneration blastema. Inhibition of emm function by heat treatment during regenerative outgrowth rapidly blocked regeneration. This block was associated with reduced proliferation in the proximal blastema and expansion of the nonproliferative distal blastemal zone. Positional cloning revealed that the emm phenotype is caused by a mutation in the orthologue of yeast sly1, a gene product involved in protein trafficking. sly1 is upregulated in the newly formed blastema as well as during regenerative outgrowth. Thus, sly1 is essential for blastemal organization and proliferation during two stages of fin regeneration.
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Affiliation(s)
- Alex Nechiporuk
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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11
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Abstract
Complex tissue regeneration involves exquisitely coordinated proliferation and patterning of adult cells after severe injury or amputation. Certain lower vertebrates such as urodele amphibians and teleost fish have a greater capacity for regeneration than mammals. However, little is known about molecular mechanisms of regeneration, and cellular mechanisms are incompletely defined. To address this deficiency, we and others have focused on the zebrafish model system. Several helpful tools and reagents are available for use with zebrafish, including the potential for genetic approaches to regeneration. Recent studies have shed light on the remarkable ability of zebrafish to regenerate fins.
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Affiliation(s)
- Kenneth D Poss
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital, Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Poss KD, Nechiporuk A, Hillam AM, Johnson SL, Keating MT. Mps1 defines a proximal blastemal proliferative compartment essential for zebrafish fin regeneration. Development 2002; 129:5141-9. [PMID: 12399306 DOI: 10.1242/dev.129.22.5141] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One possible reason why regeneration remains enigmatic is that the dominant organisms used for studying regeneration are not amenable to genetic approaches. We mutagenized zebrafish and screened for temperature-sensitive defects in adult fin regeneration. The nightcap mutant showed a defect in fin regeneration that was first apparent at the onset of regenerative outgrowth. Positional cloning revealed that nightcapencodes the zebrafish orthologue of mps1, a kinase required for the mitotic checkpoint. mps1 expression was specifically induced in the proximal regeneration blastema, a group of cells that normally proliferate intensely during outgrowth. The nightcap mutation caused severe defects in these cells. However, msxb-expressing blastemal cells immediately distal to this proliferative region did not induce mps1and were retained in mutants. These results indicate that the proximal blastema comprises an essential subpopulation of the fin regenerate defined by the induction and function of Mps1. Furthermore, we show that molecular mechanisms of complex tissue regeneration can now be dissected using zebrafish genetics.
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Affiliation(s)
- Kenneth D Poss
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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Abstract
Previous studies of zebrafish fin regeneration led to the notion that the regeneration blastema is a homogeneous population of proliferating cells. Here, we show that the blastema consists of two components with markedly distinct proliferation properties. During early blastema formation, proliferating cells are evenly distributed. At the onset of regenerative outgrowth, however, blastemal cells are partitioned into two domains. Proximal blastemal cells proliferate at a high rate, shifting from a median G2 of more than 6 hours to approximately 1 hour. By contrast, the most distal blastemal cells do not proliferate. There is a gradient of proliferation between these extremes. Using bromodeoxyuridine incorporation and anti-phosphohistone H3 labeling, we find a 50-fold difference in proliferation across the gradient that extends approximately 50 μm, or ten cell diameters. We show that during early regeneration, proliferating blastemal cells express msxb, a homeodomain transcriptional repressor. While msxb is widely expressed among proliferating cells during blastema formation, its expression becomes restricted to a small number of non-proliferating, distal blastemal cells during regenerative outgrowth. Bromodeoxyuridine pulse-chase experiments show that distal and proximal blastemal cells are formed from proliferating, msxb-positive blastemal cells, not from preexisting slow-cycling cells. These data support the idea that blastema formation results from dedifferentiation of intraray mesenchymal cells. Based on these findings, we propose a new model of zebrafish fin regeneration in which the function of non-proliferating, msxb-expressing, distal blastemal cells is to specify the boundary of proliferation and provide direction for regenerative outgrowth.
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Affiliation(s)
- Alex Nechiporuk
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital, Boston, MA 02115, USA
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Abstract
Following amputation of a urodele limb or teleost fin, the formation of a blastema is a crucial step in facilitating subsequent regeneration. Using the zebrafish caudal fin regeneration model, we have examined the hypothesis that fibroblast growth factors (Fgfs) initiate blastema formation from fin mesenchyme. We find that fibroblast growth factor receptor 1 (fgfr1) is expressed in mesenchymal cells underlying the wound epidermis during blastema formation and in distal blastemal tissue during regenerative outgrowth. fgfr1 transcripts colocalize with those of msxb and msxc, putative markers for undifferentiated, proliferating cells. A zebrafish Fgf member, designated wfgf, is expressed in the regeneration epidermis during outgrowth. Furthermore, we show that a specific inhibitor of Fgfr1 applied immediately following fin amputation blocks blastema formation, without obvious effects on wound healing. This inhibitor blocks the proliferation of blastemal cells and the onset of msx gene transcription. Inhibition of Fgf signaling during ongoing fin regeneration prevents further outgrowth while downregulating the established expression of blastemal msx genes and epidermal sonic hedgehog. Our findings indicate that zebrafish fin blastema formation and regenerative outgrowth require Fgf signaling.
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Affiliation(s)
- K D Poss
- Howard Hughes Medical Institute, Eccles Institute of Human Genetics, University of Utah Health Sciences Center, 15N 2030E, Salt Lake City, Utah, 84112, USA
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15
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Abstract
To assess the level of heterozygosity within two commonly used inbred mapping zebrafish strains, C32 and SJD, we genotyped polymorphic CA-repeat markers randomly dispersed throughout the zebrafish genome. (For clarity purposes we will primarily use the term polymorphic to define polymorphism between strains, and the term heterozygous to address heterogeneity within a strain.) Eight male individuals each from C32 and SJD stocks were typed for 235 and 183 markers, respectively. Over 90% of the markers typed were polymorphic between these two strains. We found a limited number of heterozygous markers persisting in clusters within each inbred line. In the SJD strain, these were mainly limited to a few telomeric regions or regions otherwise distant from centromeres. As expected, centromeric regions were homozygous in the SJD strain, consistent with its derivation from a single half-tetrad individual. In contrast, heterozygous clusters were distributed randomly throughout the genome in the C32 strain, and these clusters could be detected with linked polymorphic markers. Nevertheless, most regions of the C32 strain are homozygous for CA-repeat markers in current stocks. This identification of the heterozygous regions within C32 and SJD lines should permit rapid fixation of these remaining regions in future generations of inbreeding. In addition, we established levels of polymorphism between the inbred, C32 and SJD, strains and three other commonly used strains, the *AB, WIK, and Florida wild type (hereafter referred as EKK), with CA-repeat markers as well as SSCP polymorphisms. These data will maximize the use of these strains in mapping experiments.
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Affiliation(s)
- A Nechiporuk
- Department of Human Genetics, Eccles Institute of Human Genetics, Utah 84112, USA.
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Nechiporuk T, Huynh DP, Figueroa K, Sahba S, Nechiporuk A, Pulst SM. The mouse SCA2 gene: cDNA sequence, alternative splicing and protein expression. Hum Mol Genet 1998; 7:1301-9. [PMID: 9668173 DOI: 10.1093/hmg/7.8.1301] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is caused by expansion of a CAG trinucleotide repeat located in the coding region of the human SCA2 gene. Sequence analysis revealed that SCA2 is a novel gene of unknown function. In order to provide insights into the molecular mechanisms of pathogenesis of SCA2 and to identify conserved domains, we isolated and characterized the mouse homolog of the SCA2 gene. Sequence and amino acid analysis revealed 89% identity at the nucleotide and 91% identity at the amino acid level. However, there was no extended polyglutamine tract in the mouse SCA2 cDNA, suggesting that the normal function of SCA2 is not dependent on this domain. Northern blot analysis of different mouse tissues indicated that the mouse SCA2 gene was expressed in most tissues, but at varying levels. Alternative splicing seen in human SCA2 was conserved in the mouse. By northern blot analysis, SCA2 was expressed during embryogenesis as early as day 8 of gestation (E8). Immunohistochemical staining using affinity-purified antibodies demonstrated that ataxin 2 was expressed in the cytoplasm of Purkinje cells as well as in other neurons of the CNS.
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Affiliation(s)
- T Nechiporuk
- Rose Moss Laboratory for Parkinson's and Neurodegenerative Diseases, CSMC Burns and Allen Research Institute and Division of Neurology, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA 90048, USA
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Sahba S, Nechiporuk A, Figueroa KP, Nechiporuk T, Pulst SM. Genomic structure of the human gene for spinocerebellar ataxia type 2 (SCA2) on chromosome 12q24.1. Genomics 1998; 47:359-64. [PMID: 9480749 DOI: 10.1006/geno.1997.5131] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is a member of a group of neurodegenerative diseases that are caused by instability of a DNA CAG repeat. We report the genomic structure of the SCA2 gene. Its 25 exons, encompassing approximately 130 kb of genomic DNA, were mapped onto the physical map of the region. Exonic sizes varied from 37 to 890 bp, and intronic sizes ranged from 323 bp to more than 15 kb. The CAG repeat was contained in the 5' coding region of the gene in exon 1. Determination of the splice junction sequences indicated the presence of only one deviation from the GT-AG rule at the donor splice site of intron 9, which contained a GC instead of a GT dinucleotide. Exon 10, immediately downstream from this rare splice donor site, was alternatively spliced. Alternative splicing does not affect the reading frame and is predicted to encode an isoform containing 70 amino acids less.
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Affiliation(s)
- S Sahba
- Division of Neurology, Cedars-Sinai Medical Center, CSMC Burns and Allen Research Institute, Los Angeles, California, 90048, USA
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18
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Nechiporuk T, Nechiporuk A, Sahba S, Figueroa K, Shibata H, Chen XN, Korenberg JR, de Jong P, Pulst SM. A high-resolution PAC and BAC map of the SCA2 region. Genomics 1997; 44:321-9. [PMID: 9325053 DOI: 10.1006/geno.1997.4886] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The spinocerebellar ataxia type 2 (SCA2) gene has been localized to chromosome 12q24.1. To characterize this region and to aid in the identification of the SCA2 gene, we have constructed a 3.9-Mb physical map, which covers markers D12S1328 and D12S1329 known to flank the gene. The map comprises a contig of 84 overlapping yeast artificial chromosomes (YACs), P1 artificial chromosomes (PACs), and bacterial artificial chromosomes (BACs) onto which we placed 82 PCR markers. We localized eight genes and expressed sequence tags on this map, many of which had not been precisely mapped before. In contrast to YACs, which showed a high degree of chimerism and deletions in this region, PACs and BACs were stable. Only 1 in 65 PACs contained a small deletion, and 2 in 18 BACs were chimeric. The high-resolution physical map, which was used in the identification of the SCA2 gene, will be useful for the positional cloning of other disease genes mapped to this region.
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Affiliation(s)
- T Nechiporuk
- Rose Moss Laboratory for Parkinson's and Neurodegenerative Diseases, CSMC Burns and Allen Research Institute, University of California, Los Angeles School of Medicine 90048, USA
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Pulst SM, Nechiporuk A, Nechiporuk T, Gispert S, Chen XN, Lopes-Cendes I, Pearlman S, Starkman S, Orozco-Diaz G, Lunkes A, DeJong P, Rouleau GA, Auburger G, Korenberg JR, Figueroa C, Sahba S. Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2. Nat Genet 1996; 14:269-76. [PMID: 8896555 DOI: 10.1038/ng1196-269] [Citation(s) in RCA: 742] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The gene for spinocerebellar ataxia type 2 (SCA2) has been mapped to 12q24.1. A 1.1-megabase contig in the candidate region was assembled in P1 artificial chromosome and bacterial artificial chromosome clones. Using this contig, we identified a CAG trinucleotide repeat with CAA interruptions that was expanded in patients with SCA2. In contrast to other unstable trinucleotide repeats, this CAG repeat was not highly polymorphic in normal individuals. In SCA2 patients, the repeat was perfect and expanded to 36-52 repeats. The most common disease allele contained (CAG)37, one of the shortest expansions seen in a CAG expansion syndrome. The repeat occurs in the 5'-coding region of SCA2 which is a member of a novel gene family.
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Affiliation(s)
- S M Pulst
- Rose Moss Laboratory for Parkinson's and Neurodegenerative Diseases, CSMC Burns and Allen Research Institute, Los Angeles, California, USA
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Baser ME, Mautner VF, Ragge NK, Nechiporuk A, Riccardi VM, Klein J, Sainz J, Pulst SM. Presymptomatic diagnosis of neurofibromatosis 2 using linked genetic markers, neuroimaging, and ocular examinations. Neurology 1996; 47:1269-77. [PMID: 8909442 DOI: 10.1212/wnl.47.5.1269] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Neurofibromatosis 2 (NF2) is an autosomal dominant disorder that causes nervous system tumors and ocular abnormalities such as early-onset lenticular opacities. We assessed the clinical spectrum of NF2 at the time of presymptomatic DNA diagnosis in at-risk first-degree relatives. We studied five multigeneration NF2 families with short tandem repeat markers near the NF2 gene (NF2); gadolinium-enhanced high-resolution magnetic resonance imaging (GE-MRI); and ocular, dermatologic, and neurologic examinations. Eleven of 31 asymptomatic at-risk first-degree relatives were predicted by segregation analysis to be NF2 mutation carriers. Nine of the 11 NF2 mutation carriers were clinically evaluated. Four mutation carriers, including a 7-year-old, had vestibular schwannomas, early-onset cataracts, or both. However, five mutation carriers did not have clinical abnormalities, including a 38-year-old with normal cranial and spinal GE-MRIs and a normal ocular examination. These results indicate that clinical abnormalities can be present in young, but absent in middle-aged, presymptomatic NF2 mutation carriers. By identifying presymptomatic NF2 mutation carriers, DNA diagnosis of NF2 can improve genetic counseling and clinical management, and possibly reduce psychosocial difficulties in at-risk individuals.
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Affiliation(s)
- M E Baser
- Division of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
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Nechiporuk A, Lopes-Cendes I, Nechiporuk T, Starkman S, Andermann E, Rouleau GA, Weissenbach JS, Kort E, Pulst SM. Genetic mapping of the spinocerebellar ataxia type 2 gene on human chromosome 12. Neurology 1996; 46:1731-5. [PMID: 8649579 DOI: 10.1212/wnl.46.6.1731] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The dominant spinocerebellar ataxias are a genetically heterogeneous group of diseases leading to premature death of neurons in the cerebellum and other parts of the nervous system. The mutation causing SCA1 is on human chromosome (CHR) 6p and SCA3 is on CHR 14q. To refine the location of the SCA2 gene on CHR 12q, we performed genetic linkage analysis between the SCA2 locus and nine Ioci (D12S58, D12S78, D12S317, D12S330, D12S353, D12S84, D12S105, D12S79, and PLA2) in three SCA2 families. The highest pairwise lod scores were obtained between SCA2 and D12S84/D12S105 and D12S79. We determined the best order and genetic distances among these loci in ten multigenerational families by multipoint linkage analysis and established the following order: D12S101-D12S58/IGF1- D12S78-D12S317-D12S330/D12S353-D12S84/D 12S105-D12S79-PLA2. Using this genetic map, multipoint linkage analysis placed SCA2 between D12S84/D12S105 and D12S79.
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Affiliation(s)
- A Nechiporuk
- Neurogenetics Laboratory, Cedars-Sinai Medical Center, UCLA School of Medicine 90048, USA
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Nechiporuk T, Nechiporuk A, Guan X, Frederick R, Figueroa K, Chumakov I, Korenberg JR, de Jong PJ, Pulst SM. Identification of three new microsatellite markers in the spinocerebellar ataxia type 2 (SCA2) region and 1.2 Mb physical map. Hum Genet 1996; 97:462-7. [PMID: 8834243 DOI: 10.1007/bf02267067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease recently mapped to chromosome 12q close to the locus D12S84 by genetic linkage analysis. To generate additional genetic markers in the SCA2 region, we constructed a physical map of the region using yeast artificial chomosome (YAC), P1 artificial chromosome (PAC) and cosmid clones. The physical map was found to agree well with the genetic map. Three novel microsatellite markers were isolated and physically mapped. A novel approach to isolate CAG repeats directly from YAC DNAs is described.
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Affiliation(s)
- T Nechiporuk
- Division of Neurology, University of California at Los Angeles 90048, USA
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Abstract
PURPOSE To evaluate the ocular abnormalities in patients with clinically diagnosed neurofibromatosis 2 and asymptomatic gene carriers. METHODS Probands were ascertained through a surgical otolaryngology practice. In a cross-sectional study, we examined 49 patients with neurofibromatosis 2, 30 offspring of patients, and, as a comparison group, 18 parents and siblings of patients with sporadic neurofibromatosis 2. The examination included a complete neuro-ophthalmic assessment, physical examination, and, for patients and first-degree relatives at risk, cranial and spinal magnetic resonance imaging with gadolinium enhancement, if not previously performed. RESULTS The most common ocular abnormalities were posterior subcapsular or capsular, cortical, or mixed lens opacities in 33 (67%) of 49 patients with neurofibromatosis 2 and retinal hamartomas in 11 (22%). We used segregation analysis to determine the mutation carrier status of six at-risk offspring who were 30 years old or younger in two multigeneration families. Three asymptomatic mutation carriers had cataracts, whereas those who were predicted not to carry the mutation did not have cataracts. Asymptomatic mutation carriers may have developmental abnormalities of the eye that are detectable in childhood or adolescence, a finding that may assist in early diagnosis of the disease. CONCLUSIONS A variety of ocular abnormalities are present in neurofibromatosis 2, including cataracts, retinal hamartomas, and ocular motor deficits. Many of these are developmental or acquired early in life and may assist in presymptomatic diagnosis. For screening at-risk relatives of patients with neurofibromatosis 2, the types of cataract that are most suggestive of neurofibromatosis 2 are plaque-like posterior subcapsular or capsular cataract and cortical cataract with onset under the age of 30 years.
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Affiliation(s)
- N K Ragge
- Division of Ophthalmology, Childrens Hospital, Los Angeles, California, USA
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Affiliation(s)
- J Sainz
- Cedars-Sinai Medical Center, University of California at Los Angeles 90048
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Affiliation(s)
- J Sainz
- Department of Neurology, Cedars-Sinai Medical Center, University of California at Los Angeles 90048
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Nechiporuk A, Fain P, Kort E, Nee LE, Frommelt E, Polinsky RJ, Korenberg JR, Pulst SM. Linkage of familial Alzheimer disease to chromosome 14 in two large early-onset pedigrees: effects of marker allele frequencies on lod scores. Am J Med Genet 1993; 48:63-6. [PMID: 8357039 DOI: 10.1002/ajmg.1320480113] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Alzheimer disease (AD) is a devastating neurodegenerative disease leading to global dementia. In addition to sporadic forms of AD, familial forms (FAD) have been recognized. Mutations in the amyloid precursor protein (APP) gene on chromosome (CHR) 21 have been shown to cause early-onset AD in a small number of pedigrees. Recently, linkage to markers on CHR 14 has been established in several early-onset FAD pedigrees. We now report lod scores for CHR 14 markers in two large early-onset FAD pedigrees. Pairwise linkage analysis suggested that in these pedigrees the mutation is tightly linked to the loci D14S43 and D14S53. However, assumptions regarding marker allele frequencies had a major and often unpredictable effect on calculated lod scores. Therefore, caution needs to be exercised when single pedigrees are analyzed with marker allele frequencies determined from the literature or from a pool of spouses.
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Affiliation(s)
- A Nechiporuk
- Division of Neurology, Cedars-Sinai Medical Center, UCLA School of Medicine 90048
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