Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.16 (calcineurin)
 17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytochrome P450c17 catalyzes 17 alpha-hydroxylation needed for cortisol synthesis and 17,20 lyase activity needed to produce sex steroids. Serine phosphorylation of P450c17 specifically increases 17,20 lyase activity, but the physiological factors regulating this effect remain unknown. Treating human adrenal NCI-H295A cells with the phosphatase inhibitors okadaic acid, fostriecin, and cantharidin increased 17,20 lyase activity, suggesting involvement of protein phosphatase 2A (PP2A) or 4 (PP4). PP2A but not PP4 inhibited 17,20 lyase activity in microsomes from cultured cells, but neither affected 17 alpha-hydroxylation. Inhibition of 17,20 lyase activity by PP2A was concentration-dependent, could be inhibited by okadaic acid, and was restored by endogenous protein kinases. PP2A but not PP4 coimmunoprecipitated with P450c17, and suppression of PP2A by small interfering RNA increased 17,20 lyase activity. Phosphoprotein SET found in adrenals inhibited PP2A, but not PP4, and fostered 17,20 lyase activity. The identification of PP2A and SET as post-translational regulators of androgen biosynthesis suggests potential additional mechanisms contributing to adrenarche and hyperandrogenic disorders such as polycystic ovary syndrome.
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PMID:Protein phosphatase 2A and phosphoprotein SET regulate androgen production by P450c17. 1244 89

Insulin resistance, a key factor in the pathogenesis of polycystic ovary syndrome (PCOS), is associated with a reduction in activation of muscle glycogen synthase. A 5-bp insertion-deletion polymorphism in the (AU)AT-rich element (ARE) within the 3'-untranslated region of the gene encoding the muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PPP1R3) has been associated with insulin resistance and type 2 diabetes. The present study was undertaken to examine the relationship of the ARE polymorphism with clinical and hormonal characteristics of women with PCOS. We studied 186 women with PCOS who had undergone a standard 75-g oral glucose tolerance test and measurement of serum androgen and SHBG levels. Among the largest cohort of nondiabetic subjects (Caucasian, n = 112), the presence of the deletion allele (ARE-2) was associated with insulin resistance and hyperandrogenemia. There was no association of the ARE polymorphism with body mass index or blood glucose concentration during the oral glucose tolerance test. Subjects who were homozygous for the insertion allele (ARE-1/1) had a mean insulin area under the curve (99,116 +/- 6,625 pmol/liter.min) that was significantly lower than that in either the heterozygous (ARE-1/2) (132,195 +/- 12,340 pmol/liter.min) or homozygous (ARE-2/2) (164,661 +/- 24,219 pmol/liter.min) deletion groups. In addition, ARE-1/1 subjects had significantly lower serum concentrations of dehydroepiandrosterone sulfate compared with ARE-2/2 subjects (4.2 +/- 0.3 vs. 6.6 +/- 0.7 micromol/liter) and a trend toward lower levels of free testosterone (78.8 +/- 6.5 vs. 114.1 +/- 30.8 pmol/liter). Studies of diabetic and nondiabetic PCOS women of other racial and ethnic backgrounds will be necessary to assess the impact of this and other variants in PPP1R3 upon the phenotype and natural history of women with PCOS.
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PMID:Association of the (AU)AT-rich element polymorphism in PPP1R3 with hormonal and metabolic features of polycystic ovary syndrome. 1518 Oct 86

SET (SE Translocation) protein carries out multiple functions including those for protein phosphatase 2A (PP2A) inhibition, histone modification, DNA repair, and gene regulation. SET overexpression has been detected in brain neurons of patients suffering Alzheimer's disease, follicle theca cells of Polycystic Ovary Syndrome (PCOS) patients, and ovarian cancer cells, indicating that SET may play a pathological role for these disorders. SET transcript 2, produced by a specific promoter, represents a major transcript variant in different cell types. In this study, we characterized the transcriptional activation of human SET transcript 2 promoter in HeLa cells. Promoter deletion experiments and co-transfection assays indicated that ZFX, the Zinc finger and X-linked transcription factor, was able to transactivate the SET promoter. A proximal promoter region containing four ZFX-binding sites was found to be critical for the ZFX-mediated transactivation. Mutagenesis study indicated that the ZFX-binding site located the closest to the transcription start site accounted for most of the ZFX-mediated transactivity. Manipulation of ZFX levels by overexpression or siRNA knockdown confirmed the significance and specificity of the ZFX-mediated SET promoter activation. Chromatin immunoprecipitation results verified the binding of ZFX to its cognate sites in the SET promoter. These findings have led to identification of ZFX as an upstream factor regulating SET gene expression. More studies are required to define the in vivo significance of this mechanism, and specifically, its implication for several benign and malignant diseases related to SET dysregulation.
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PMID:Zinc Finger and X-Linked Factor (ZFX) Binds to Human SET Transcript 2 Promoter and Transactivates SET Expression. 2777 3

SET (SE translocation, SET), a constitutive inhibitor of protein phosphatase 2A (PP2A), is a multifunctional oncoprotein involved in DNA replication, histone modification, nucleosome assembly, gene transcription and cell proliferation. It is widely expressed in human tissues including the gonadal system and brain. Intensive studies have shown that overexpressed SET plays an important role in the development of Alzheimer's disease (AD), and may also contribute to the malignant transformation of breast and ovarian cancers. Recent studies indicated that through interaction with PP2A, SET may upregulate androgen biosynthesis and contribute to hyperandrogenism in polycystic ovary syndrome (PCOS) patients. This review article summarizes data concerning the SET expression in ovaries from PCOS and normal women, and analyzes the role/regulatory mechanism of SET for androgen biosynthesis in PCOS, as well as the significance of this action in the development of PCOS. The potential value of SET-triggered pathway as a therapeutic target and the application of anti-SET reagents for treating hyperandrogenism in PCOS patients are also discussed.
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PMID:Pathologic significance of SET/I2PP2A-mediated PP2A and non-PP2A pathways in polycystic ovary syndrome (PCOS). 2783 88