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)

Recent evidence suggests a novel role of bradykinin (BK) in stimulating gene transcription. This study examined the effect of BK on nuclear factor kappaB (NF-kappaB) activation and IL-1beta synthesis in human epithelial cells. Stimulation of A549 cells and primary bronchial epithelial cells with BK rapidly activated NF-kappaB. BK also increased the level of secreted immunoreactive IL-1beta in A549 culture supernatants, an effect that was blocked by actinomycin D and the B2 BK receptor antagonist HOE-140. The role of NF-kappaB activation in BK-induced IL-1beta synthesis was demonstrated by the ability of BK to stimulate increased chloramphenicol acetyltransferase (CAT) activity in A549 cells transfected with a reporter plasmid containing three kappaB enhancers from the IL-1beta gene, while deletion of the kappaB enhancer sequences eliminated BK-stimulated CAT activity. C3 transferase exoenzyme, an inhibitor of Rho, abolished BK-induced NF-kappaB activation at 10 microg/ml and significantly inhibited BK-stimulated IL-1beta synthesis at 5 microg/ml. A dominant-negative form of RhoA (T19N) inhibited BK-stimulated reporter gene expression in a dose-dependent and kappaB-dependent manner. Cotransfection of A549 cells with an expression vector encoding a constitutively active form of RhoA (Q63L) along with the IL-1beta promoter-CAT reporter plasmid resulted in a marked increase in NF-kappaB activity compared with transfection with the IL-1beta promoter-CAT reporter plasmid alone. These results demonstrate that BK stimulates NF-kappaB activation and IL-1beta synthesis in A549 cells, and that RhoA is both necessary and sufficient to mediate this effect.
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PMID:Role of the Rho GTPase in bradykinin-stimulated nuclear factor-kappaB activation and IL-1beta gene expression in cultured human epithelial cells. 951 Feb 9

We have recently reported that the geranylgeranyltransferase I inhibitor GGTI-298 arrests human tumor cells at the G1 phase of the cell cycle and increases the protein and RNA levels of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1). Here, we show that GGTI-298 acts at the transcriptional level to induce p21(WAF1/CIP1) in a human pancreatic carcinoma cell line, Panc-1. This upregulation of p21(WAF1/CIP1) promoter was selective, since GGTI-298 inhibited serum responsive element- and E2F-mediated transcription. A functional analysis of the p21(WAF1/CIP1) promoter showed that a GC-rich region located between positions -83 and -74, which contains a transforming growth factor beta-responsive element and one Sp1-binding site, is sufficient for the upregulation of p21(WAF1/CIP1) promoter by GGTI-298. Electrophoretic mobility shift assays showed a small increase in the amount of DNA-bound Sp1-Sp3 complexes. Furthermore, the analysis of Sp1 transcriptional activity in GGTI-298-treated cells by using GAL4-Sp1 chimera or Sp1-chloramphenicol acetyltransferase reporter revealed a significant increase in Sp1-mediated transcription. Moreover, GGTI-298 treatment also resulted in increased Sp1 and Sp3 phosphorylation. These results suggest that GGTI-298-mediated upregulation of p21(WAF1/CIP1) involves both an increase in the amount of DNA-bound Sp1-Sp3 and enhancement of Sp1 transcriptional activity. To identify the geranylgeranylated protein(s) involved in p21(WAF1/CIP1) transcriptional activation, we analyzed the effects of the small GTPases Rac1 and RhoA on p21(WAF1/CIP1) promoter activity. The dominant negative mutant of RhoA, but not Rac1, was able to activate p21(WAF1/CIP1). In contrast, constitutively active RhoA repressed p21(WAF1/CIP1). Accordingly, the ADP-ribosyl transferase C3, which specifically inhibits Rho proteins, enhanced the activity of p21(WAF1/CIP1). Taken together, these results suggest that one mechanism by which GGTI-298 upregulates p21(WAF1/CIP1) transcription is by preventing the small GTPase RhoA from repressing p21(WAF1/CIP1) induction.
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PMID:p21(WAF1/CIP1) is upregulated by the geranylgeranyltransferase I inhibitor GGTI-298 through a transforming growth factor beta- and Sp1-responsive element: involvement of the small GTPase rhoA. 981 84