Premature ovarian failure affects up to 1% of women by the age of 40. Although the etiology of premature ovarian failure remains largely unknown, a genetic basis has been determined for selective cases. Mutations in the gene encoding a forkhead transcription, Forkhead L2 (FOXL2) has been associated with this disorder. FOXL2 is present in the ovary and preliminary data reveals that it is localized to less differentiated granulosa cells of small and medium follicles and functions as a transcriptional represser of the Steroidogenic Acute Regulatory (StAR) gene, a marker of granulosa cell differentiation. Since FOXL2 may function as a represser of granulosa cell differentiation and steroidogenesis, we propose to evaluate FOXL2 transcriptional activity on other genes involved in the Steroidogenic cascade which contain putative forkhead consensus sites. Since FOXL2 may function as a represser of granulosa cell differentiation and hence steroidogenesis, we will evaluate steroid production in the granulosa cell following FOXL2 overexpression. In order to understand some of the underlying mechanism of FOXL2 regulation in the ovary, we performed a yeast two-hybrid screen using an ovarian fusion cDNA library to isolate FOXL2-interacting proteins. Large Tumor Suppressor Gene 1 (LATS1), a putative serine/threonine kinase and ovarian tumor suppressor gene, was identified to interact strongly with FOXL2. Mutations in LATS1, like mutations in FOXL2 produce a similar ovarian phenotype, premature ovarian failure. Thus, we propose that LATS1 and FOXL2 share a common pathway for follicular regulation. We will first localize LATS1 in the ovary, followed by defining the precise interaction between LATS1 and FOXL2. Since LATS1 is a serine/threonine kinase, and other forkhead family members are regulated by phosphorylation, we propose that FOXL2 transcriptional activity will be regulated by phosphorylation. Thus, we will also determine phosphorylation of FOXL2 by LATS1 and its regulation of transcriptional activity using our functional assay as well as through cellular localization. The proposed study could provide a better understanding of the mechanisms underlying premature ovarian failure. ? ? ?

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD047603-02
Application #
7289689
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Taymans, Susan
Project Start
2006-09-21
Project End
2011-06-30
Budget Start
2007-07-01
Budget End
2008-06-30
Support Year
2
Fiscal Year
2007
Total Cost
$253,195
Indirect Cost
Name
Cedars-Sinai Medical Center
Department
Type
DUNS #
075307785
City
Los Angeles
State
CA
Country
United States
Zip Code
90048
Kuo, Fang-Ting; Fan, Kenneth; Bentsi-Barnes, Ikuko et al. (2012) Mouse forkhead L2 maintains repression of FSH-dependent genes in the granulosa cell. Reproduction 144:485-94
Pisarska, Margareta D; Barlow, Gillian; Kuo, Fang-Ting (2011) Minireview: roles of the forkhead transcription factor FOXL2 in granulosa cell biology and pathology. Endocrinology 152:1199-208
Kuo, Fang-Ting; Bentsi-Barnes, Ikuko K; Barlow, Gillian M et al. (2011) Mutant Forkhead L2 (FOXL2) proteins associated with premature ovarian failure (POF) dimerize with wild-type FOXL2, leading to altered regulation of genes associated with granulosa cell differentiation. Endocrinology 152:3917-29
Pisarska, Margareta D; Kuo, Fang-Ting; Bentsi-Barnes, Ikuko K et al. (2010) LATS1 phosphorylates forkhead L2 and regulates its transcriptional activity. Am J Physiol Endocrinol Metab 299:E101-9
Bentsi-Barnes, Ikuko K; Kuo, Fang-Ting; Barlow, Gillian M et al. (2010) Human forkhead L2 represses key genes in granulosa cell differentiation including aromatase, P450scc, and cyclin D2. Fertil Steril 94:353-6
Pisarska, Margareta D; Kuo, Fang-Ting; Tang, Dahai et al. (2009) Expression of forkhead transcription factors in human granulosa cells. Fertil Steril 91:1392-4
Kuo, Fang-Ting; Bentsi-Barnes, Ikuko K; Barlow, Gillian M et al. (2009) Sumoylation of forkhead L2 by Ubc9 is required for its activity as a transcriptional repressor of the Steroidogenic Acute Regulatory gene. Cell Signal 21:1935-44