Mechanisms of Retina Regeneration in Zebrafish.

Stem Cells;Retina Regeneration;Zebrafish;Tubulin;Central Nervous System Regeneration;Biological Chemistry

Fausett, Blake V.Turner, David ;

University of Michigan

关键词: Stem Cells;    Retina Regeneration;    Zebrafish;    Tubulin;    Central Nervous System Regeneration;    Biological Chemistry;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/62277/bfausett_3.pdf?sequence=3&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Teleost fish have a remarkable capacity to regenerate their central nervous system (CNS) following damage.Although successful regeneration has been observed for decades, little is known of the molecular events that govern it.Alpha1-tubulin is a neuron-specific microtubule protein whose expression is induced in the developing and regenerating CNS.By investigating how expression of an early marker of regeneration such as alpha1-tubulin is regulated, our lab hoped to identify genes involved in regeneration.Transgenic zebrafish harboring an alpha1-tubulin promoter fragment driving GFP reporter expression were created to study alpha1-tubulin gene regulation during successful CNS regeneration.This promoter mediates gene induction in retinal ganglion cells during optic nerve regeneration and in a subset of Müller glia that proliferate following retinal injury.To further characterize transgene expressing Müller glia, we generated transgenic fish harboring an alpha1-tubulin promoter fragment that is specifically induced in these cells following retinal damage.Transgene expression, BrdU-labeling and stem cell marker expression suggested that alpha1-tubulin-expressing Müller glia dedifferentiate and become multipotent progenitors in response to retinal injury.In addition, GFP and BrdU-mediated lineage tracing combined with retinal gene expression analysis indicated that alpha1-tubulin-expressing Müller glia are capable of generating retinal neurons and glia.These data strongly suggest alpha1-tubulin-expressing Müller glia dedifferentiate and mediate regeneration of the injured zebrafish retina.Because alpha1-tubulin expression is induced in proliferating Müller glia following retinal injury, we searched for DNA elements that mediate alpha1-tubulin transgene expression in these cells.We report the identification of an E-box in the alpha1-tubulin promoter that is necessary for its activity in proliferating Müller glia.In a search for E-box binding proteins that may mediate alpha1-tubulin induction during retina regeneration, we found that the basic helix-loop-helix transcription factor ascl1a is induced in Müller glia within four hours following injury and regulates alpha1-tubulin promoter activity via the E-box in vitro.Knockdown of ascl1a expression in the regenerating retina confirmed that ascl1a regulates alpha1-tubulin transgene expression and is necessary for the generation of retinal progenitors and their differentiating progeny in vivo.These data suggest ascl1a is a key regulator of retina regeneration in zebrafish.