Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.99.3 (PRE)
 1,923 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nontransformed steroid receptors contain several non-steroid binding proteins, such as hsp90, hsp70, and p59. Recently, we and others have shown that p59 (FKBP59) is an immunophilin which binds two potent immunosuppressants, FK506 and rapamycin. This raises the possibility that FK506 or rapamycin may modify the function of steroid receptors. To develop this line of inquiry, we chose a yeast model system in which the human progesterone receptor form B (hPR-B) was cotransformed with a reporter gene. The reporter contains two copies of a progesterone response element/glucocorticoid response element (PRE/GRE) upstream of the CYC1 promoter which are linked to the lacZ gene of Escherichia coli. We found that FK506 potentiated the ability of progesterone in activating transcription. To gain insight into the mechanism of FK506's regulation of PR action, we questioned whether calcineurin is involved, because it has been shown that FK506 is a specific inhibitor of calcineurin, a Ca(2+)- and calmodulin-regulated phosphatase, through the formation of an FKBP12-FK506-calcineurin-calmodulin complex. We found that 15-O-desmethyl-FK520, an FK506 analogue which is an excellent ligand of FKBP12, but a poor inhibitor of calcineurin, failed to induce the same effect as FK506. We also found that calmidazolium, a calmodulin antagonist, mimicked FK506's action. Furthermore, immunoblot analysis showed that both FK506 and calmidazolium potentiated the effect of progesterone in decreasing the mobility of hPR-B upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This suggests that FK506 and calmidazolium may cooperate with progesterone in increasing the level of hPR-B phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Potentiation of progesterone receptor-mediated transcription by the immunosuppressant FK506. 752 Dec 10

Previous studies have shown that progestin induces the production of fibronectin (FN) and its mRNA content in human endometrial stromal cells. The mechanism of the upregulation was unclear. In the present study, we provide evidence that hPR regulates the FN promoter activity mainly through the CRE/AP1 site located in the proximal region of the promoter in human decidual fibroblasts. Various lengths of the proximal region of the FN promoter were linked to the reporter vector to construct promoter-reporter plasmids and were then transfected into human decidual fibroblasts. Deletion and mutation analysis showed that CRE/AP1 and Sp1 sites in the proximal region mediated the basal promoter activity. To evaluate progestin-mediated transcriptional activation, decidual fibroblasts were transfected with p300 (FN promoter-reporter construct) and hPR expression vector. Cells treated with medroxyprogesterone acetate (MPA) increased the promoter activity ranging from 2.5- to 9-fold determined in 10 decidual specimens. hPRA enhanced activation was stronger than that of hPRB. Structural analysis of hPR showed that DNA and ligand binding domains are essential for the activation, and missing the TAF1 domain weakens the activation. The proximal promoter region of the FN gene lacks a canonical PRE site. Mutation at the CRE/AP1 site eliminated the upregulation by progestin. To evaluate the interaction of hPR with the CRE/AP1 site, the CRE/AP1 site was mutated to the consensus AP1 cis-element (TGACGTCA, -172 to -165 bp, mutated to TGAC_TCA) which eliminated the CREB binding. FN promoter activity derived from p300AP1 mutant was found to be higher than that of p300. These results showed that hPR interacts with the AP1 binding proteins, but not with CREB. Progestin treatment or overexpression hPR did not alter appreciably the content of c-jun or c-fos in decidual fibroblasts nuclear extracts. Antibody to hPR (hPRa3), which precipitated hPR also coprecipitated c-jun and c-fos, whereas CREB was not precipitated by hPRa3. The observation implies that hPRs are brought to the FN promoter region by AP1 proteins to enhance the transcription. In summary, this study provides molecular evidence that the CRE/AP1 site and c-jun/c-fos in decidual fibroblasts mediate the hPR-enhanced activation of FN transcription.
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PMID:Progesterone receptor (hPR) upregulates the fibronectin promoter activity in human decidual fibroblasts. 1461 84