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Carrillo-Rosas S, Weber C, Fievet L, Messaddeq N, Karam A, Trottier Y. Loss of zebrafish Ataxin-7, a SAGA subunit responsible for SCA7 retinopathy, causes ocular coloboma and malformation of photoreceptors. Hum Mol Genet 2020; 28:912-927. [PMID: 30445451 DOI: 10.1093/hmg/ddy401] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/31/2018] [Accepted: 11/10/2018] [Indexed: 12/26/2022] Open
Abstract
Polyglutamine (polyQ) expansion in Ataxin-7 (ATXN7) results in spinocerebellar ataxia type 7 (SCA7) and causes visual impairment. SCA7 photoreceptors progressively lose their outer segments (OSs), a structure essential for their visual function. ATXN7 is a subunit of the transcriptional coactivator Spt-Ada-Gcn5 Acetyltransferase complex, implicated in the development of the visual system in flies. To determine the function of ATXN7 in the vertebrate eye, we have inactivated ATXN7 in zebrafish. While ATXN7 depletion in flies led to gross retinal degeneration, in zebrafish, it primarily results in ocular coloboma, a structural malformation responsible for pediatric visual impairment in humans. ATXN7 inactivation leads to elevated Hedgehog signaling in the forebrain, causing an alteration of proximo-distal patterning of the optic vesicle during early eye development and coloboma. At later developmental stages, malformations of photoreceptors due to incomplete formation of their OSs are observed and correlate with altered expression of crx, a key transcription factor involved in the formation of photoreceptor OS. Therefore, we propose that a primary toxic effect of polyQ expansion is the alteration of ATXN7 function in the daily renewal of OS in SCA7. Together, our data indicate that ATXN7 plays an essential role in vertebrate eye morphogenesis and photoreceptor differentiation, and its loss of function may contribute to the development of human coloboma.
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Affiliation(s)
- Samantha Carrillo-Rosas
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
| | - Chantal Weber
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
| | - Lorraine Fievet
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
| | - Nadia Messaddeq
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
| | - Alice Karam
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
| | - Yvon Trottier
- Institute of Genetics and Molecular and Cellular Biology (IGBMC).,Centre National de la Recherche Scientifique, UMR7104.,Institut National de la Santé et de la Recherche Médicale, U1254.,University of Strasbourg, Illkirch, 67000, France
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Zampedri C, Tinoco-Cuellar M, Carrillo-Rosas S, Diaz-Tellez A, Ramos-Balderas JL, Pelegri F, Maldonado E. Zebrafish P54 RNA helicases are cytoplasmic granule residents that are required for development and stress resilience. Biol Open 2016; 5:1473-1484. [PMID: 27489304 PMCID: PMC5087673 DOI: 10.1242/bio.015826] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [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] [Indexed: 12/28/2022] Open
Abstract
Stress granules are cytoplasmic foci that directly respond to the protein synthesis status of the cell. Various environmental insults, such as oxidative stress or extreme heat, block protein synthesis; consequently, mRNA will stall in translation, and stress granules will immediately form and become enriched with mRNAs. P54 DEAD box RNA helicases are components of RNA granules such as P-bodies and stress granules. We studied the expression, in cytoplasmic foci, of both zebrafish P54 RNA helicases (P54a and P54b) during development and found that they are expressed in cytoplasmic granules under both normal conditions and stress conditions. In zebrafish embryos exposed to heat shock, some proportion of P54a and P54b helicases move to larger granules that exhibit the properties of genuine stress granules. Knockdown of P54a and/or P54b in zebrafish embryos produces developmental abnormalities restricted to the posterior trunk; further, these embryos do not form stress granules, and their survival upon exposure to heat-shock conditions is compromised. Our observations fit the model that cells lacking stress granules have no resilience or ability to recover once the stress has ended, indicating that stress granules play an essential role in the way organisms adapt to a changing environment. Summary: Stress granules are formed by mRNAs stalled in translation during stress conditions. P54 RNA helicases from zebrafish reside in cytoplasmic granules and are essential for heat-shock resilience.
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Affiliation(s)
- Cecilia Zampedri
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Maryana Tinoco-Cuellar
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Samantha Carrillo-Rosas
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F. México, México, 04510
| | - Abigail Diaz-Tellez
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
| | - Jose Luis Ramos-Balderas
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F. México, México, 04510
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Wisconsin 53706, USA
| | - Ernesto Maldonado
- EvoDevo Laboratory, Unidad de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, México, 77580
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Guzman A, Ramos-Balderas JL, Carrillo-Rosas S, Maldonado E. A stem cell proliferation burst forms new layers of P63 expressing suprabasal cells during zebrafish postembryonic epidermal development. Biol Open 2013; 2:1179-86. [PMID: 24244854 PMCID: PMC3828764 DOI: 10.1242/bio.20136023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [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: 07/02/2013] [Accepted: 08/22/2013] [Indexed: 11/29/2022] Open
Abstract
Organ growth during development is a highly regulated process with both temporal and spatial constraints. Epidermal stratification is essential for skin growth and development. Although the zebrafish has been well studied, it is not known when and how epidermal stratification occurs. This is because beyond the first five days of development our knowledge is currently limited. We found that epidermal stratification in zebrafish begins when the larvae reach a standard length (SL) of 6 mm at approximately 25 days of age. Over the next four days (from a SL of 6 to 9 mm), epidermis thickness increases almost four-fold. This represents a sudden increase in organ size, since for the previous 20 days of development, the epidermis has been only two layers thick. This pattern is different from that observed in mammals that undergo continuous stratification from E14.5–E18.5. To study how stem cell proliferation gives rise to the new epidermal layers, we used a combination of markers: one for cell proliferation (proliferating cell nuclear-antigen PCNA) and one for epidermal stem cells (P63 transcription factor). We identified, throughout the stratification process, two different waves of cell division. Initially, the most basal epidermal cells divided and generated a subset of suprabasal cells (possibly transient-amplifying cells); within the next several days, the basal cells stopped dividing, and the suprabasal cells began proliferation, giving rise to most of the cell types in the new layers. This part of the process is similar to what has been recently found during epidermal stratification in mammals.
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Affiliation(s)
- Aida Guzman
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria , 04510, México, D.F. , México
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