Sox2 plays a role in the induction of amacrine and Müller glial cells in mouse retinal progenitor cells.
OBJECTIVE
The transcription factor Sox2 plays important roles in both human and mouse retinal development. Although loss-of-function mutations in Sox2 have been studied in mice, gain-of-function experiments in the neural retina have been lacking.


METHODS
The detailed expression pattern of Sox2 in the developing mouse retina was examined by immunohistochemistry. Then, Sox2 was expressed in a retinal explant culture prepared from E17 mouse embryos by retrovirus-mediated gene transfer to examine its role in retinal development. In addition, shRNA was used to suppress Sox2 in a retinal explant using a retrovirus-mediated system.


RESULTS
Sox2 was expressed throughout the neuroblastic layer in the embryonic retina, but only in the inner nuclear layer in the mature retina. Double immunostaining revealed that Sox2 was expressed in Müller glial cells and in a subset of amacrine cells. Forced expression of Sox2 in a mouse retinal explant culture resulted in the dramatic accumulation of amacrine cells in the inner nuclear layer; in addition, cells expressing amacrine cell markers were also found on the innermost side of the outer nuclear layer. The expression of Pax6, which plays an important role in amacrine cell differentiation, was observed in the Sox2-expressing cells, and Sox2 activated the Pax6 promoter to drive luciferase expression in Y79 cells. A decrease in retinal progenitor cell proliferation accompanied these effects. The suppression of Sox2 expression by shRNA resulted in a decreased number of cells in the inner nuclear layer.


CONCLUSIONS
Therefore, ectopic Sox2 expression can induce amacrine cells in the mouse retina from stage E17 onward, possibly by facilitating cell cycle exit.
Lin
Ya-ping
YP
Department of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Ouchi
Yasuo
Y
Satoh
Shinya
S
Watanabe
Sumiko
S
D025042:Amacrine Cells / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D005136:Eye Proteins / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D018014:Gene Transfer Techniques; D018398:Homeodomain Proteins / Q000235:genetics; D051379:Mice; D008813:Mice, Inbred ICR; D009457:Neuroglia / Q000378:metabolism*; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics; D012160:Retina / Q000196:embryology*; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology*; D015533:Transcriptional Activation
D017931:DNA Primers; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012333:RNA, Messenger; D012097:Repressor Proteins; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse