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Goudreau, G.* ; Petrou, P.* ; Reneker, L.W.* ; Graw, J. ; Löster, J. ; Gruss, P.*

Mutually regulated expression of Pax6 and Six3 and its implications for the Pax6 haploinsufficient lens phenotype.

Proc. Natl. Acad. Sci. U.S.A. 99, 8719-8724 (2002)
Open Access Gold as soon as Publ. Version/Full Text is submitted to ZB.
Pax6 is a key regulator of eye development in vertebrates and invertebrates, and heterozygous loss-of-function mutations of the mouse Pax6 gene result in the Small eye phenotype, in which a small lens is a constant feature. To provide an understanding of the mechanisms underlying this haploinsufficient phenotype, we evaluated in Pax6 heterozygous mice the effects of reduced Pax6 gene dosage on the activity of other transcription factors regulating eye formation. We found that Six3 expression was specifically reduced in lenses of Pax6 heterozygous mouse embryos. Interactions between orthologous genes from the Pax and Six families have been identified in Drosophila and vertebrate species, and we examined the control of Pax6 and Six3 gene expression in the developing mouse lens. Using in vitro and transgenic approaches, we found that either transcription factor binds regulatory sequences from the counterpart gene and that both genes mutually activate their expression. These studies define a functional relationship in the lens in which Six3 expression is dosage-dependent on Pax6 and where, conversely, Six3 activates Pax6. Accordingly, we show a rescue of the Pax6 haploinsufficient lens phenotype after lens-specific expression of Six3 in transgenic mice. This phenotypic rescue was accompanied by cell proliferation and activation of the platelet-derived growth factor alpha-R/cyclin D1 signaling pathway. Our findings thus provide a mechanism implicating gene regulatory interactions between Pax6 and Six3 in the tissue-specific defects found in Pax6 heterozygous mice.
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Publication type Article: Journal article
Document type Scientific Article
Keywords homeodomain proteins; transcription factors; eye development
Language english
Publication Year 2002
HGF-reported in Year 0
ISSN (print) / ISBN 0027-8424
e-ISSN 1091-6490
Quellenangaben Volume: 99, Issue: , Pages: 8719-8724 Article Number: , Supplement: ,
Publisher National Academy of Sciences
Reviewing status Peer reviewed
POF-Topic(s) 30204 - Cell Programming and Repair
Research field(s) Genetics and Epidemiology
PSP Element(s) G-500500-002
Erfassungsdatum 2002-08-05