Functional interactions between FOXC1 and PITX2 underlie the sensitivity to FOXC1 gene dose in Axenfeld-Rieger syndrome and anterior segment dysgenesis - PubMed (original) (raw)

. 2006 Mar 15;15(6):905-19.

doi: 10.1093/hmg/ddl008. Epub 2006 Jan 31.

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Functional interactions between FOXC1 and PITX2 underlie the sensitivity to FOXC1 gene dose in Axenfeld-Rieger syndrome and anterior segment dysgenesis

Fred B Berry et al. Hum Mol Genet. 2006.

Abstract

Axenfeld-Rieger ocular dysgenesis is associated with mutations of the human PITX2 and FOXC1 genes, which encode transcription factors of the homeodomain and forkhead types, respectively. We have identified a functional link between FOXC1 and PITX2 which we propose underpins the similar Axenfeld-Rieger phenotype caused by mutations of these genes. FOXC1 and PITX2A physically interact, and this interaction requires crucial functional domains on both proteins: the C-terminal activation domain of FOXC1 and the homeodomain of PITX2. Immunofluorescence further shows PITX2A and FOXC1 to be colocalized within a common nuclear subcompartment. Furthermore, PITX2A can function as a negative regulator of FOXC1 transactivity. This work ties both proteins into a common pathway and offers an explanation of why increased FOXC1 gene dosage produces a phenotype resembling that of PITX2 deletions and mutations. Ocular phenotypes arise despite the deregulated expression of FOXC1-target genes through mutations in FOXC1 or PITX2. Ultimately, PITX2 loss of function mutations have a compound effect: the reduced expression of PITX2-target genes coupled with the extensive activation of FOXC1-regulated targets. Our findings indicate that the functional interaction between FOXC1 and PITX2A underlies the sensitivity to FOXC1 gene dosage in Axenfeld-Rieger syndrome and related anterior segment dysgeneses.

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