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General Comment |
NCBI Summary:
This gene encodes a member of the cytosolic phospholipase A2 group IV family. The enzyme catalyzes the hydrolysis of membrane phospholipids to release arachidonic acid which is subsequently metabolized into eicosanoids. Eicosanoids, including prostaglandins and leukotrienes, are lipid-based cellular hormones that regulate hemodynamics, inflammatory responses, and other intracellular pathways. The hydrolysis reaction also produces lysophospholipids that are converted into platelet-activating factor. The enzyme is activated by increased intracellular Ca(2+) levels and phosphorylation, resulting in its translocation from the cytosol and nucleus to perinuclear membrane vesicles. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2015]
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Comment |
An ovulatory gonadotropin stimulus increases cytosolic phospholipase A2 expression and activity in granulosa cells of primate periovulatory follicles. Duffy DM et al. (2005) Prostaglandins (PGs) produced within ovarian follicles in response to the ovulatory gonadotropin surge are essential for follicle rupture and oocyte release. Arachidonic acid, the common precursor for PG synthesis, is cleaved from membrane phospholipids via the activity of phospholipase A2 (PLA2). The purpose of this study was to determine which PLA2 form(s) is involved in PG production by primate periovulatory follicles. Gonadotropins were administered to cynomolgus monkeys to stimulate multiple follicular development; human chorionic gonadotropin (hCG) initiated periovulatory events. Granulosa cells and whole ovaries were obtained before (0 h), and 12, 24, and 36 h after hCG administration. Granulosa-lutein cells were also obtained from women undergoing infertility treatment. mRNA for cytosolic (c)PLA2 and secretory (s)PLA2V, but not sPLA2IIA, was expressed by granulosa cells. cPLA2 mRNA levels were low at 0 h, elevated by 12 h, and remained high 24-36 h after hCG administration. sPLA2V mRNA levels were low at 0 h and did not change in response to hCG. cPLA2 and sPLA2V were detected by immunocytochemistry in granulosa cells of periovulatory follicles before and at all times after hCG administration. PLA2 activity was low in lysates of granulosa cells obtained 0-24 h after hCG and was elevated in granulosa cells obtained 36 h after hCG administration. A cPLA2-selective inhibitor decreased both PLA2 activity in monkey granulosa cell lysates and PGE2 accumulation in cultures of human granulosa-lutein cells. cPLA2 is primarily or exclusively responsible for the gonadotropin-stimulated mobilization of arachidonic acid necessary for PG production by primate periovulatory follicles.//////////////////
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Comment |
Expression of Phospholipase A2 Group IVA (PLA2G4A) Is Up-Regulated by Human Chorionic Gonadotropin in Bovine Granulosa Cells of Ovulatory Follicles. Diouf MN et al. Prostaglandins (PG) are required for the ovulatory process, and their biosynthesis depends on the initial release of arachidonic acid (AA) from membrane phospholipids. We hypothesized that phospholipase A2 group IVA (PLA2G4A) expression is up-regulated in granulosa cells (GC) at ovulation. We have characterized bovine PLA2G4A cDNA, and investigated its spatio- temporal regulation at the mRNA and protein levels in human chorionic gonadotropin (hCG)- induced ovulatory follicles and in vitro, using forskolin-stimulated GC. Regulation of PLA2G4A mRNA expression was studied in GC obtained from bovine follicles collected at different developmental stages: small follicles (2-4 mm), dominant follicles at day 5 (D5) of the estrous cycle, ovulatory follicles 24 h following injection of hCG, and corpus luteum at D5. PLA2G4A mRNA increased by 14-fold in GC of hCG-stimulated versus dominant follicles (P < 0.0001). Follicular walls obtained from ovulatory follicles recovered at 0, 6, 12, 18 and 24 h post-hCG injection showed an initial 16-fold increase in PLA2G4A transcript at 12 h that reached a 45-fold increase at 24 h, as compared to 0 h (P < 0.0001). Immunoblots of GC extracts showed an initial induction of the PLA2G4A protein at 18 h post-hCG reaching a maximum at 24 h. Immunohistochemistry observations showed that PLA2G4A signal was mainly observed in mural GC compared to antral GC in hCG-stimulated follicles. Stimulation of cultured bovine GC with 10 microM of forskolin, caused an increase in PLA2G4A mRNA and protein. Ovulation is associated with an LH/hCG-dependent induction of PLA2G4A in GC via the adenylyl cyclase/cAMP pathway.
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Mutations |
1 mutations
Species: human
Mutation name:
type: naturally occurring
fertility: subfertile
Comment: American Ginseng Regulates Gene Expression to Protect against Premature Ovarian Failure in Rats. Zhu L et al. (2015) Premature ovarian failure (POF) is defined as lost ovarian functions before the age of 40. Three possible molecular markers (PLA2G4A, miR-29a, and miR-144) have been identified in our previous study by integrated analysis of mRNA and miRNA expression profiles. The present study aimed to evaluate American ginseng root's protective potential against POF by studying transcriptional and protein variations between American ginseng treatments and controls in rats. 4-Vinylcyclohexene diepoxide (VCD) was administered to rats for 14 days to induce POF. Additionally, American ginseng was administered to POF rats for one month, and PLA2G4A, miR-29a, and miR-144 expressions were measured in rat ovaries by qRT-PCR. PLA2G4A protein expression was examined by Western Blot, and PGE2, LH, FSH, and E2 serum levels were detected by ELISA. PLA2G4A mRNA and protein were downregulated in American ginseng-treated rats, miR-29a and miR-144 levels increased, and PGE2 serum levels decreased, while LH, FSH, and E2 increased compared to POF induction alone. Analysis of transcriptional and protein variations suggested that American ginseng protects the ovary against POF by regulating prostaglandin biosynthesis, ovulation, and preventing ovarian aging. High hormone levels (PGE2, FSH, and LH) were reduced, and E2 secretion approached normal levels, leading to improved POF symptoms and abnormal ovulation.//////////////////
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