Taz-tead1 links cell-cell contact to zeb1 expression, proliferation, and dedifferentiation in retinal pigment epithelial cells.
PURPOSE. The Hippo signaling pathway imposes the cell contact inhibition that establishes organ size and tissue topology from Drosophila to mammals. This pathway regulates activity of the Yap and Taz transcription factors, which link epithelial-mesenchymal transition (EMT) to cell proliferation. Here, the authors provide evidence that Taz and its coactivator, Tead1, regulate expression of the EMT transcription factor Zeb1 to control RPE cell proliferation and differentiation. METHODS. Real-time PCR was used to examine mRNA expression during RPE dedifferentiation in primary cultures of RPE cells and after knockdown of Yap and Taz by lentivirus shRNA. Immunofluorescence was used to follow subcellular localization of proteins in cells. Chromatin immunoprecipitation was used to detect Taz at the Zeb1 promoter in vivo. RESULTS. Zeb1 is overexpressed during RPE dedifferentiation, leading to cell proliferation, EMT, and repression of the RPE specification transcription factor gene Mitf. Taz-TEAD1 translocation to the nucleus coincides with loss of cell-cell contact and with onset of Zeb1 expression in the nucleus. shRNA knockdown of Taz prevented the overexpression of Zeb1 and, in turn, prevented proliferation, repression of Mitf and Mitf target genes, and EMT when RPE cells were placed in primary culture. Taz binds to the Zeb1 promoter in vivo, suggesting that it directly induces Zeb1 transcription. CONCLUSIONS. These results provide evidence of a molecular mechanism linking cell-cell contact to cell proliferation and dedifferentiation in RPE cells.
Liu
Yongqing
Y
Departments of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, USA.
Xin
Ying
Y
Ye
Fei
F
Wang
Wei
W
Lu
Qingxian
Q
Kaplan
Henry J
HJ
Dean
Douglas C
DC
D000217:Acyltransferases; D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites; D002450:Cell Communication / Q000502:physiology*; D054337:Cell Dedifferentiation / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D005434:Flow Cytometry; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000502:physiology*; D000071799:Zinc Finger E-box-Binding Homeobox 1
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051741:Kruppel-Like Transcription Factors; D012333:RNA, Messenger; D000091262:TEA Domain Transcription Factors; C083215:Tead1 protein, mouse; D014157:Transcription Factors; C519422:ZEB1 protein, mouse; D000071799:Zinc Finger E-box-Binding Homeobox 1; D000217:Acyltransferases; C486363:tafazzin protein, mouse