NCBI Summary:
The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes, or E1s, ubiquitin-conjugating enzymes, or E2s, and ubiquitin-protein ligases, or E3s. This gene encodes a member of the E2 ubiquitin-conjugating enzyme family. This enzyme is required for post-replicative DNA damage repair. Multiple alternatively spliced transcript variants have been found for this gene and they encode distinct isoforms.
General function
Cell cycle regulation, Enzyme, Ligase
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Cellular localization
Nuclear
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Ovarian function
Oogenesis, Oocyte maturation
Comment
Sumoylation of Forkhead L2 by Ubc9 is required for its activity as a transcriptional repressor of the Steroidogenic Acute Regulatory gene. Kuo FT et al. Forkhead L2 (FOXL2) is a member of the forkhead/hepatocyte nuclear factor 3 (FKH/HNF3) gene family of transcription factors and acts as a transcriptional repressor of the Steroidogenic Acute Regulatory (StAR) gene, a marker of granulosa cell differentiation. FOXL2 may play a role in ovarian follicle maturation and prevent premature follicle depletion leading to premature ovarian failure. In this study, we found that FOXL2 interacts with Ubc9, an E2-conjugating enzyme that mediates sumoylation, a key mechanism in transcriptional regulation. FOXL2 and Ubc9 are co-expressed in granulosa cells of small and medium ovarian follicles. FOXL2 is sumoylated by Ubc9, and this Ubc9-mediated sumoylation is essential to the transcription activity of FOXL2 on the StAR promoter. As FOXL2 is endogenous to granulosa cells, we generated a stable cell line expressing FOXL2 and found that activity of the StAR promoter in this cell line is greatly decreased in the presence of Ubc9. The sumoylation site was identified at lysine 25 of FOXL2. Mutation of lysine 25 to arginine leads to loss of transcriptional repressor activity of FOXL2. Taken together, we propose that Ubc9-mediated sumoylation at lysine 25 of FOXL2 is required for transcriptional repression of the StAR gene and may be responsible for controlling the development of ovarian follicles.
Genes whose expression is detected by cDNA array hybridization: transcription factors, cell signaling and extracellular communication Rozenn Dalbi?Tran and Pascal Mermilloda
Expression regulated by
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Ovarian localization
Oocyte
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Follicle stages
Primordial
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Arraztoa JA, et al 2005 reported the identification of genes expressed in primate primordial oocytes.