Developmental wave of Brn3b expression leading to RGC fate specification is synergistically maintained by miR-23a and miR-374.
Differential regulation of Brn3b is essential for the Retinal Ganglion Cell (RGC) development in the two phases of retinal histogenesis. This biphasic Brn3b regulation is required first, during early retinal histogenesis for RGC fate specification and secondly, during late histogenesis, where Brn3b is needed for RGC axon guidance and survival. Here, we have looked into how the regulation of Brn3b at these two stages happens. We identified two miRNAs, miR-23a and miR-374, as regulators of Brn3b expression, during the early stage of RGC development. Temporal expression pattern of miR-23a during E10-19, PN1-7, and adult retina revealed an inverse relation with Brn3b expression. Though miR-374 did not show such a pattern, its co-expression with miR-23a evidently inhibited Brn3b. We further substantiated these findings by ex vivo overexpression of these miRNAs in E14 mice retina and found that miR-23a and miR-374 together brings about a change in Brn3b expression pattern in ganglion cell layer (GCL) of the developing retina. From our results, it appears that the combined expression of these miRNAs could be regulating the timing of the wave of Brn3b expression required for early ganglion cell fate specification and later for its survival and maturation into RGCs. Taken together, here we provide convincing evidences for the existence of a co-ordinated mechanism by miRNAs to down regulate Brn3b that will ultimately regulate the development of RGCs from their precursors.
Department of Neurobiology, Neuro Stem Cell Biology Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, 695014, India.
Vazhanthodi A
VA
Rasheed
Sreekumaran
S
Sreekanth
Sivadasan B
SB
Dhanesh
Mundackal S
MS
Divya
Thulasi S
TS
Divya
Palakkottu K
PK
Akhila
Chandramohan
C
Subashini
Krishnankutty
K
Chandrika Sivakumar
Ani V
AV
Das
Jackson
J
James
D000818:Animals; D001369:Axons / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D058953:Neural Stem Cells / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology*; D051381:Rats; D012160:Retina / Q000254:growth & development / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000502:physiology*; D046509:Tissue Culture Techniques; D050820:Transcription Factor Brn-3B / Q000378:metabolism*; D014162:Transfection
D018398:Homeodomain Proteins; C000599421:MIRN374b microRNA, mouse; D035683:MicroRNAs; C534062:Mirn23b microRNA, mouse; C085559:Pou4f2 protein, mouse; D050820:Transcription Factor Brn-3B
Brn3b; RGC differentiation; miR-23a; miR-374; retinal development