Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.12 (PKG)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitogenic cell proliferation requires a rapid and transient H2O2 generation, which is blocked by catalase or PKA activators. Previously, we observed that anemic HIV(+) individuals expressed acidic pIs of catalase in RBC with significantly high activities [Mol Cell Biochem 165: 77-81, 1996]. These findings led us to hypothesize that cell signaling molecules regulate catalase to control cell mitogenesis. To test the hypothesis, we determined (i) whether RBC counts correlate with their catalase activities, (ii) whether protein kinases and phosphatases alter catalase activity in vitro, and (iii) whether protein kinase activators increase catalase activity to suppress proliferation of cultured cells. The results indicated that RBC counts inversely correlated with RBC catalase activities in both HIV(+) (r: -0.6769, r2: 0.4582, n: 69 male, p < 0.0001) and HIV(-) (r: -0.3827, r2: 0.1464, n: 177 male, p < 0.0001) populations. Catalytic PKA, PKC and Casein Kinase II, but none of PKG, Ca2+/calmodulin kinase II and p34cdc/cyclinB, rapidly elevated catalase activity in vitro by up to 2-fold. Whereas a major CAT subunit (60 kDa) showed immunoreactive phosphoserine and phosphothreonine, the kinases- and gamma-32P-ATP-dependent phosphorylation occurred with a minor component (110 kDa). Among PKC isozymes examined, PKCzeta was the most effective modulator followed by PKCgamma, and protein phosphatase 1gamma and 2A decreased the catalase activity. PKA and PKCzeta activators of forskolin and okadaic acid increased catalase activity and 110 kDa expression in NIH3T3 cells up to 2.4-fold and suppressed the cell growth, showing an inverse correlation of the indices (r: -0.9286, r2: 0.8622, n: 18, p < 0.0001). Taken together, these results suggest for the first time that catalase is under the regulation of cell signaling molecules and capable of modulating mitogenic cell proliferation.
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PMID:Regulation of catalase enzyme activity by cell signaling molecules. 1248 79

We report the first mutational study of thymidine kinase 1 (TK1) performed in human solid tumors. We sequenced cDNAs representing the complete coding region of TK1 in human breast (n=22) and colorectal (n=26) cancer. Codon 106 near the ATP binding site constantly differed (ATG --> GTG; Met --> Val) from the one deposited by Bradshaw and Deininger in the Genbank database (Accession number NM_003258). Silent polymorphisms at codon 11 (CCC --> CCT; Pro --> Pro) and codon 75 (GCG --> GCA; Ala --> Ala) were frequently detected in tumors as well as in normal tissues. In breast cancer the two polymorphisms were observed in 63.6% of the samples analyzed. No significant association could be found between polymorphisms and TK activity. In colorectal cancer the incidence of the two changes was 73.1% and 69.2%, respectively. Interestingly, one colon cancer with high cytosolic TK activity displayed two missense mutations located in and near the putative phosphorylation site by tyrosine kinase (s) (TAT --> CAT; Tyr --> His) and by cAMP-, cGMP-dependent protein kinase (TAC --> TGC; Tyr --> Cys), respectively; adjacent normal mucosa showed no mutation. This may open new avenues that imply TK1 activity in tumor cell proliferation.
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PMID:Mutation analysis in the coding sequence of thymidine kinase 1 in breast and colorectal cancer. 1269 56