NCBI Summary:
Stearoyl-CoA desaturase (SCD; EC 1.14.99.5) is an integral membrane protein of the endoplasmic reticulum that catalyzes the formation of monounsaturated fatty acids from saturated fatty acids. SCD may be a key regulator of energy metabolism with a role in obesity and dislipidemia. Four SCD isoforms, Scd1 through Scd4, have been identified in mouse. In contrast, only 2 SCD isoforms, SCD1 (MIM 604031) and SCD5, have been identified in human. SCD1 shares about 85% amino acid identity with all 4 mouse SCD isoforms, as well as with rat Scd1 and Scd2. In contrast, SCD5 shares limited homology with the rodent SCDs and appears to be unique to primates (Wang et al., 2005).[supplied by OMIM]
General function
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Cellular localization
Cytoplasmic
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Ovarian function
Antral follicle growth, Oocyte maturation
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Gene expression in human cumulus cells: one approach to oocyte competence. Feuerstein P et al. BACKGROUND Dialogue between the oocyte and cumulus cells is essential for oocyte maturation. A prospective laboratory research project was designed to evaluate transcription of specific genes in cumulus cells harvested before intracytoplasmic sperm injection from pre-ovulatory follicles, according to individual oocyte nuclear maturity and developmental competence. Genes were chosen because their expression was induced by the LH peak [Steroidogenic Acute Regulatory protein (STAR), Cyclooxygenase 2 (COX2 or PTGS2), Amphiregulin (AREG)] or because they were involved in oocyte lipidic metabolism [Stearoyl-Coenzyme A Desaturase 1 and 5 (SCD1 and SCD5)] or in gap-junctions [Connexin 43 (CX43 or GJA1)]. METHODS mRNA levels in cumulus cells were assessed by real-time PCR. RESULTS Expression levels of all genes investigated, except Cx43, were increased after resumption of meiosis. Nuclear maturation was thus associated with increased expression of STAR, COX2, AREG, SCD1 and SCD5 by cumulus cells. When considering only cumulus associated with metaphase II oocytes, gene expression was independent of morphological status at Day 2. In contrast, transcript levels were lower and distributed over a narrower range in cumulus enclosing oocytes achieving blastocyst development at Day 5/6 than in cumulus enclosing oocytes unable to develop beyond the embryo stage. CONCLUSION Further developmental potential from embryo to blastocyst stage was associated with lower expression in a narrow range for these genes.
Expression regulated by
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Ovarian localization
Cumulus, Granulosa, Luteal cells
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Expression and Regulation of the SCD2 Desaturase in the Rat Ovary Moreau C, et al .
Despite the significant role of the lipid reserve in cell structure and function, very few studies have provided detailed descriptions of the unsaturated fatty acid synthesis in the ovary. Here, we have showed by RT-PCR, Northern-blot and Western-blot, the mRNA and protein expression of SCD2 (Stearoyl-CoA desaturase 2) delta 9 desaturase in rat ovary. We have also localized Scd2 mRNA by in situ hybridization mainly in granulosa cells of antral follicles, the cumulus oophorus and the corpus lutea. Interestingly, no or very weakly SCD2 expression was observed in primordial follicles and oocytes. After eCG injection for 24h in immature 22-day old rats, the level of SCD2 expression and SCD activity in ovary was increased approximately 4-fold (p<0.05) and the response was further increased 48h after hCG treatment. As expected, eCG/hCG treatment increased the expression of the steroidogenesis enzymes (CYP11A1 and HSD3B) and STAR. We have also showed a decrease in the SCD2 expression and SCD activity in the corpus luteum at days 10 and 15 compared to day 3 of gestation, which is paralleled to a decrease in the expression of the steroidogenesis enzymes and STAR. To investigate the molecular mechanisms involved in the regulation of SCD2 expression in ovary, we performed primary culture of rat granulosa cells. We showed that both IGF1 (7.5 x 10(-8)g/ml) and FSH (350 x 10(-8)g/ml) increased by about three-fold the SCD2 expression and SCD activity. Using specific inhibitors, we demonstrated that the MAPK3/MAP1 and PIK3R1/AKT pathways are involved in the IGF1-and FSH- induced SCD2 expression, respectively. The SCD2 is expressed and active in rat ovary and may be involved in the regulation of follicular growth and/or the oocyte maturation.