Aromatase Is a Direct Target of FOXL2: C134W in Granulosa Cell Tumors via a Single Highly Conserved Binding Site in the Ovarian Specific Promoter
Open Access
- 20 December 2010
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 5 (12), e14389
- https://doi.org/10.1371/journal.pone.0014389
Abstract
Granulosa cell tumors (GCT) of the ovary often express aromatase and synthesize estrogen, which in turn may influence their progression. Recently a specific point mutation (C134W) in the FOXL2 protein was identified in >94% of adult-type GCT and it is likely to contribute to their development. A number of genes are known to be regulated by FOXL2, including aromatase/CYP19A1, but it is unclear which are direct targets and whether the C134W mutation alters their regulation. Recently, it has been reported that FOXL2 forms a complex with steroidogenic factor 1 (SF-1) which is a known regulator of aromatase in granulosa cells. In this work, the human GCT-derived cell lines KGN and COV434 were heterozygous and wildtype for the FOXL2:C134W mutation, respectively. KGN had abundant FOXL2 mRNA expression but it was not expressed in COV434. Expression of exogenous FOXL2:C134W in COV434 cells induced higher expression of a luciferase reporter for the ovarian specific aromatase promoter, promoter II (PII) (−516bp) than expression of wildtype FOXL2, but did not alter induction of a similar reporter for the steroidogenic acute regulatory protein (StAR) promoter (−1300bp). Co-immunoprecipitation confirmed that FOXL2 bound SF-1 and that it also bound its homologue, liver receptor homologue 1 (LRH-1), however, the C134W mutation did not alter these interactions or induce a selective binding of the proteins. A highly conserved putative binding site for FOXL2 was identified in PII. FOXL2 was demonstrated to bind the site by electrophoretic mobility shift assays (EMSA) and site-directed mutagenesis of this element blocked its differential induction by wildtype FOXL2 and FOXL2:C134W. These findings suggest that aromatase is a direct target of FOXL2:C134W in adult-type GCT via a single distinctive and highly conserved binding site in PII and therefore provide insight into the pathogenic mechanism of this mutation.Keywords
This publication has 66 references indexed in Scilit:
- Human forkhead L2 represses key genes in granulosa cell differentiation including aromatase, P450scc, and cyclin D2Fertility and Sterility, 2010
- The ovary: basic biology and clinical implicationsJCI Insight, 2010
- Sumoylation of Forkhead L2 by Ubc9 is required for its activity as a transcriptional repressor of the Steroidogenic Acute Regulatory geneCellular Signalling, 2009
- Detection of nonneutral substitution rates on mammalian phylogeniesGenome Research, 2009
- FoxL2 and Smad3 Coordinately Regulate Follistatin Gene TranscriptionOnline Journal of Public Health Informatics, 2009
- Potential targets of FOXL2, a transcription factor involved in craniofacial and follicular development, identified by transcriptomicsProceedings of the National Academy of Sciences of the United States of America, 2007
- Specific Interactions of the Wing Domains of FOXA1 Transcription Factor with DNAJournal of Molecular Biology, 2007
- Vertebrate DM domain proteins bind similar DNA sequences and can heterodimerize on DNABMC Molecular Biology, 2007
- The Human Genome Browser at UCSCGenome Research, 2002
- BLAT—The BLAST-Like Alignment ToolGenome Research, 2002