NCBI Summary:
This gene encodes a member of the a ubiquitously expressed transcription factor that controls cholesterol homeostasis by regulating transcription of sterol-regulated genes. The encoded protein contains a basic helix-loop-helix-leucine zipper (bHLH-Zip) domain and binds the sterol regulatory element 1 motif. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]
General function
Nucleic acid binding, DNA binding, Transcription factor
Comment
Cellular localization
Nuclear
Comment
candidate123
Ovarian function
Steroid metabolism
Comment
Expression regulated by
Comment
Ovarian localization
Granulosa
Comment
Genes in sterol/steroid and lipid biosynthetic pathways are targets of FSH and FOXO1 regulation in granulosa cells: evidence from cells expressing mutant forms of FOXO1. Liu Z et al. The forkhead box transcription factor FOXO1 is highly expressed in granulosa cells of growing follicles but is down-regulated by FSH in culture or by LH-induced luteinization in vivo. To analyze the function of FOXO1, we infected rat and mouse granulosa cells with adenoviral vectors expressing two FOXO1 mutants: a gain-of-function mutant FOXOA3 that has three serine residues mutated to alanines rendering this protein constitutively active and nuclear and FOXOA3-mDBD in which the DNA binding domain is mutated. The infected cells were then treated with vehicle or FSH for specific time intervals. Infection of the granulosa cells was highly efficient, caused only minimal apoptosis and maintained FOXO1 protein at levels of the endogenous protein observed in cells prior to exposure to FSH. RNA was prepared from control and adenoviral infected cells exposed to vehicle or FSH for 12 and 24h. Affymetrix microarray and data-base analyses identified, and real time RT-PCR verified, that genes within the lipid, sterol and steroidogenic biosynthetic pathways (Hmgcs1, Hmgcr, Mvk, Sqle, Lss, Cyp51, Tm7sf2, Dhcr24 and Star, Cyp11a1 and Cyp19), including two key transcriptional regulators Srebf1 and Srebf2 of cholesterol biosynthesis and steroidogenesis (Nr5a1, Nr5a2) were major targets induced by FSH and suppressed by FOXOA3 and FOXOA3-mDBD in the cultured granulosa cells. By contrast, FOXOA3 and FOXOA3-mDBD induced expression of Cyp27a1 mRNA that encodes an enzyme involved in cholesterol catabolism to oxysterols. The genes up-regulated by FSH in cultured granulosa cells were also induced in granulosa cells of preovulatory follicles and corpora lutea collected from immature mice primed with FSH (eCG) and LH (hCG), respectively. Conversely, Foxo1 and Cyp27a1 mRNAs were reduced by these same treatments. Collectively, these data provide novel evidence that FOXO1 may play a key role in granulosa cells to modulate lipid and sterol biosynthesis, thereby preventing elevated steroidogenesis during early stages of follicle development.
Follicle stages
Comment
Phenotypes
PCO (polycystic ovarian syndrome)
Mutations
1 mutations
Species: human
Mutation name: None
type: naturally occurring fertility: subfertile Comment: Association Between Single Nucleotide Polymorphisms of Sterol Regulatory Element Binding Protein-2 and Liver X Receptor a Gene and Risk of Polycystic Ovary Syndrome in a Chinese Han Population. Zhao J 2014 et al.
To investigate associations of single nucleotide polymorphisms (SNPs) rs2228314 of sterol regulatory element-binding protein-2 (SREBP-2) or rs11039155 of liver X receptor a (LXRa) with susceptibility to polycystic ovary syndrome (PCOS) in a Chinese Han population. SREBP-2 rs2228314 and LXRa rs11039155 polymorphisms were genotyped in patients with PCOS and age- and sex-matched PCOS-free controls from a Chinese Han population. A total of 605 patients with PCOS and 615 controls were recruited in this study. We found that GC and CC genotypes of rs2228314, and variant C, were associated with a significantly increased risk of PCOS. In addition, GA and AA genotypes of rs11039155, as well as variant A, were also associated with a significantly increased risk of PCOS. Our results showed that SREBP-2 rs2228314 G to C change and variant C genotype as well as LXRa rs11039155 G to A change and variant A may contribute to PCOS in Chinese Han population.
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