Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is well established that steroid receptor function requires interaction with coactivators. However, the mechanisms through which steroid receptors elicit precise assembly of coactivator complexes and the way the steroid activation signal is transduced remain elusive. Using a T47D cell line stably integrated with a mouse mammary tumor virus-chloramphenicol acetyltransferase (MMTV-CAT) reporter, we demonstrate that specific steroid receptors exhibit preferential recruitment of SRC-1 family coactivators, which determines the subsequent recruitment of specific downstream coregulator molecules. Upon ligand treatment, progesterone receptor (PR) interacted preferentially with SRC-1, which recruited CBP and significantly enhanced acetylation at K5 of histone H4. In contrast, activated glucocorticoid receptor (GR) preferentially associated with SRC-2 (TIF-2/GRIP-1), which subsequently recruited pCAF and led to specific modification of histone H3, suggesting that specific coactivators recruit distinct histone acetyltransferases to modulate the transcription of steroid-responsive genes. Loss-of-function experiments further support the predicted roles of SRC-1 and SRC-2 in, respectively, PR- and GR-mediated transcription on the MMTV promoter. This study indicates that differential recruitment of coactivators by nuclear receptors determines the assembly of coactivator complexes on target promoters to mediate specific transcription signals.
 ...
PMID:Progesterone and glucocorticoid receptors recruit distinct coactivator complexes and promote distinct patterns of local chromatin modification. 1274 80

The human progesterone receptor (PR) contains multiple Ser-Pro phosphorylation sites that are potential substrates for cyclin-dependent kinases, suggesting that PR activity might be regulated during the cell cycle. Using T47D breast cancer cells stably transfected with an mouse mammary tumor virus (MMTV) chloramphenicol acetyltransferase reporter (Cat0) synchronized in different phases of the cell cycle, we found that PR function and phosphorylation is remarkably cell cycle dependent, with the highest activity in S phase. Although PR expression was reduced in the G2/M phase, the activity per molecule of receptor was markedly reduced in both G1 and G2/M phases compared to the results seen with the S phase of the cell cycle. Although PR is recruited to the MMTV promoter equivalently in the G1 and S phases, recruitment of SRC-1, SRC-3, and, consequently, CBP is reduced in G1 phase despite comparable expression levels of SRC-1 and SRC-3. In G2/M phase, site-specific phosphorylation of PR at Ser162 and at Ser294, a site previously reported to be critical for transcriptional activity and receptor turnover, was abolished. Treatment with the histone deacetylase inhibitor trichostatin A elevated G1 and G2/M activity to that of the S phase, indicating that the failure to recruit sufficient levels of active histone acetyltransferase is the primary defect in PR-mediated transactivation.
 ...
PMID:Human progesterone receptor displays cell cycle-dependent changes in transcriptional activity. 1579 79