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The role of a lens survival pathway including sox2 and αA-crystallin in the evolution of cavefish eye degeneration
- 作者:Li Ma ; Amy Parkhurst ; William R Jeffery
- 关键词:Astyanax mexicanus ; Blind cavefish ; Lens apoptosis ; Eye degeneration ; αA ; crystallin ; Sox2 ; Cis and trans gene regulation ; Lens survival pathway
- 刊名:EvoDevo
- 出版年:2014
- 出版时间:December 2014
- 年:2014
- 卷:5
- 期:1
- 全文大小:1,576 KB
- 参考文献:1. Protas, M, Jeffery, WR (2012) Evolution and development in cave animals: from fish to crustaceans. WIRES Dev Biol 1: pp. 823-845 CrossRef
2. Jeffery, WR (2001) Cavefish as a model system in evolutionary developmental biology. Dev Biol 231: pp. 1-12 CrossRef 3. Borowsky, R (2008) Restoring sight in blind cavefish. Curr Biol 18: pp. R23-R24 CrossRef 4. Retaux, S, Casane, D (2013) Evolution of eye development in the darkness of caves: adaptation, drift, or both?. EvoDevo 4: pp. 26 CrossRef 5. Wilkens, H (1988) Evolusion and genetics of epigean and cave Astyanax fasciatus (Characidae, Pisces). Evol Biol 23: pp. 271-367 6. Jeffery, WR (2009) Regressive evolution in Astyanax cavefish. Ann Rev Genet 43: pp. 25-47 CrossRef 7. Jeffery, WR, Martasian, DP (1998) Evolution of eye regression in the cavefish Astyanax: apoptosis and the Pax-6 gene. Amer Zool 38: pp. 685-696 8. Yamamoto, Y, Jeffery, WR (2000) Central role for the lens in cave fish eye degeneration. Science 289: pp. 631-633 CrossRef 9. Alunni, A, Menuet, A, Candal, E, Penigault, JB, Jeffery, WR, Retaux, S (2007) Developmental mechanisms for retinal degeneration in the blind cavefish Astyanax mexicanus. J Comp Neurol 505: pp. 221-233 CrossRef 10. Strickler, AG, Yamamoto, Y, Jeffery, WR (2007) The lens controls cell survival in the retina: Evidence from the blind cavefish Astyanax. Dev Biol 311: pp. 512-523 CrossRef 11. Protas, M, Conrad, M, Gross, JB, Tabin, C, Borowsky, R (2007) Regressive evolution in the Mexican cave tetra, Astyanax mexicanus. Curr Biol 17: pp. 452-454 CrossRef 12. Protas, M, Tabansky, I, Conrad, M, Gross, JB, Vidal, O, Tabin, CJ, Borowsky, R (2008) Multi-trait evolution in a cave fish, Astyanax mexicanus. Evol Dev 10: pp. 196-209 CrossRef 13. Gross, JB, Protas, M, Conrad, M, Scheid, PE, Vidal, O, Jeffery, WR, Borowsky, R, Tabin, CJ (2008) Synteny and candidate gene prediction using an anchored linkage map of Astyanax mexicanus. Proc Natl Acad Sci USA 105: pp. 20106-20111 CrossRef 14. Yoshizawa, M, Yamamoto, Y, O'Quin, KE, Jeffery, WR (2012) Evolution of an adaptive behavior and its sensory receptors promotes eye regression in blind cavefish. BMC Biol 10: pp. 108 CrossRef 15. O'Quin, KE, Yoshizawa, M, Doshi, P, Jeffery, WR (2013) Quantitative genetic analysis of retinal degeneration in the blind cavefish Astyanax mexicanus. PLoS One 8: pp. e57281 CrossRef 16. Behrens, M, Wilkens, H, Schmale, H (1998) Cloning of the alphaA-crystallin genes of a blind cave form and the epigean form of Astyanax fasciatus: a comparative analysis of structure, expression and evolutionary conservation. Gene 216: pp. 319-326 CrossRef 17. Strickler, AG, Byerly, MS, Jeffery, WR (2007) Lens gene expression analysis reveals downregulation of the anti-apoptotic chaperone alphaA-crystallin during cavefish eye degeneration. Dev Genes Evol 217: pp. 771-782 CrossRef 18. Andley, UP, Song, Z, Wawrousek, EF, Bassnett, S (1998) The molecular chaperone alphaA-crystallin enhances lens epithelial cell growth and resistance to UVA stress. J Biol Chem 273: pp. 31252-31261 - 刊物主题:Developmental Biology; Evolutionary Biology; Zoology; Paleontology; Plant Genetics & Genomics;
- 出版者:BioMed Central
- ISSN:2041-9139
文摘
Background The teleost Astyanax mexicanus is a single species consisting of eyed surface-dwelling (surface fish) and blind cave-dwelling (cavefish) morphs. Cavefish eyes are lost through apoptosis of the lens, which in turn promotes the degeneration of other optic tissues. The αA-crystallin (αA-crys) gene is strongly downregulated in the cavefish lens and is located in a genomic region (QTL) responsible for eye loss. Therefore, αA-crys has been proposed as a candidate for regulating cavefish eye degeneration. The purpose of this study was to determine the mechanism of αA-crys downregulation and its role in cavefish eye degeneration. Results The involvement of αA-crys in eye degeneration was confirmed by knocking down its expression in surface fish, which led to apoptosis of the lens. The underlying reason for αA-crys downregulation in cavefish was investigated by comparing genomic αA-crys DNA sequences in surface fish and cavefish, however, no obvious cis-regulatory factors were discovered. Furthermore, the cavefish αA-crys allele is expressed in surface fish x cavefish F1 hybrids, indicating that evolutionary changes in upstream genes are most likely responsible for αA-crys downregulation. In other species, Sox2 is one of the transcription factors that regulate lens crystallin genes during eye development. Determination of sox2 expression patterns during surface fish and cavefish development showed that sox2 is specifically downregulated in the cavefish lens. The upstream regulatory function of Sox2 was demonstrated by knockdown in surface fish, which abolished αA-crys expression and induced lens apoptosis. Conclusions The results suggest that αA-crys is required for normal eye development in cavefish via suppression of lens apoptosis. The regulatory changes involved in αA-crys downregulation in cavefish are in trans-acting factors rather than cis-acting mutations in the αA-crys gene. Therefore, αA-crys is unlikely to be the mutated gene(s) associated with an Astyanax eye QTL. The results reveal a genetic pathway leading from sox2 to αA-crys that is required for survival of the lens in Astyanax surface fish. Defects in this pathway may be involved in lens apoptosis and thus a cause of cavefish eye degeneration.
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