Journal Article

Discovery of novel protein partners of the transcription factor FOXL2 provides insights into its physiopathological roles

David L'Hôte, Adrien Georges, Anne Laure Todeschini, Jae-Hong Kim, Bérénice A. Benayoun, Jeehyeong Bae and Reiner A. Veitia

in Human Molecular Genetics

Volume 21, issue 14, pages 3264-3274
Published in print July 2012 | ISSN: 0964-6906
Published online April 2012 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/dds170
Discovery of novel protein partners of the transcription factor FOXL2 provides insights into its physiopathological roles

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FOXL2 transcription factor is responsible for the Blepharophimosis Ptosis Epicantus inversus Syndrome (BPES), a genetic disease involving craniofacial malformations often associated with ovarian failure. Recently, a somatic FOXL2 mutation (p.C134W) has been reported in >95% of adult-type granulosa cell tumors. Here, we have identified 10 novel FOXL2 partners by yeast-two-hybrid screening and co-immunoprecipitation. Most BPES-inducing mutated FOXL2 proteins display aggregation in cultured cells. Here, we show that two of the partners (NR2C1 and GMEB1) can be sequestered in such aggregates. This co-aggregation can contribute to the pathogenesis of FOXL2 mutations. We have also measured the effects of FOXL2 interactants on the transcriptional regulation of a series of target promoters. Some of the partners (CXXC4, CXXC5, BANF1) were able to repress FOXL2 activity indistinctively of the promoter. Interestingly, CREM-τ2α, which acted as a repressor on most promoters, increased wild-type (WT) FOXL2 activity on two promoters (PTGS2 and CYP19A1), but was unable to increase the activity of the oncogenic mutant p.C134W. Conversely, GMEB1, which also acted as a repressor on most promoters and increased WT FOXL2 activity on the Per2 promoter, increased to a greater extent the activity of the p.C134W variant. Interestingly, partners with intrinsic pro-apoptotic effect were able to increase apoptosis induction by WT FOXL2, but not by the p.C134W mutant, whereas partners with an anti-apoptotic effect decreased apoptosis induction by both FOXL2 versions. Altogether, these results suggest that the p.C134W mutated form fails to integrate signals through protein–protein interactions to regulate target promoter subsets and in particular to induce cell death.

Journal Article.  7194 words.  Illustrated.

Subjects: Genetics and Genomics

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