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)

A rapidly emerging body of literature implicates a pivotal role for the Ca2+-calmodulin-dependent phosphatase, calcineurin, as a cellular target for a variety of Ca2+-dependent signaling pathways culminating in cardiac hypertrophy. The aim of the present study was to test whether calcineurin is involved in the signal transduction of angiotensin II (AngII)-induced cardiac myocyte hypertrophy and fibroblast hyperplasia. Firstly, we observed that calcineurin activity was significantly increased in AngII-stimulated cardiac myocytes as well as fibroblasts, but was markedly inhibited by Losartan (50 micromol/l), H7 (50 micromol/l), and Fura-2/AM (5 micromol/l). It is indicated that AngII-induced activation of calcineurin is through an ATI receptor, may be dependent on the sustained increases of [Ca2+]i, and be regulated by protein kinase C. In a second experiment, we found that cyclosporin (0.1-10micromol/l), a specific inhibitor of calcineurin, decreased the protein synthesis rate in AngII-stimulated cardiomyocytes and the DNA synthesis rate in AngII-treated fibroblasts in a dose-dependent manner. In the latter experiment, calcineurin inhibition reduced the mRNA level of the atrial natriuretic factor gene. These results indicate that calcineurin is involved in the signal transduction of AngII-induced cardiomyocyte hypertrophy and fibroblast hyperplasia.
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PMID:Involvement of calcineurin in angiotensin II-induced cardiomyocyte hypertrophy and cardiac fibroblast hyperplasia of rats. 1090 83

Angiotensin II (AngII) contributes to the maintenance of extracellular fluid volume by regulating sodium transport in the nephron. In nonepithelial cells, activation of phospholipase C (PLC) by AT-1 receptors stimulates the generation of 1,4,5-trisphosphate (IP(3)) and the release of intracellular calcium. Calcineurin, a serine-threonine phosphatase, is activated by calcium and calmodulin, and both PLC and calcineurin have been linked to sodium transport in the proximal tubule. An examination of whether AngII activates calcineurin in a model of proximal tubule epithelia (LLC-PK1 cells) was performed; AngII increased calcineurin activity within 30 s. An examination of whether AngII activates PLC in proximal tubule epithelia was also performed after first showing that all three families of PLC isoforms are present in LLC-PK1 cells. Application of AngII increased IP(3) generation by 60% within 15 s, which coincided with AngII-induced tyrosine phosphorylation of the PLC-gamma1 isoform also observed at 15 s. AngII-induced tyrosine phosphorylation was blocked by the AT-1 receptor antagonist, Losartan. Subsequently, an inhibitor of tyrosine phosphorylation blocked the AngII-induced activation of calcineurin, as did coincubation with an inhibitor of PLC activity and with an antagonist of the AT-1 receptor. It is therefore concluded that AngII stimulates calcineurin phosphatase activity in proximal tubule epithelial cells through a mechanism involving AT-1 receptor-mediated tyrosine phosphorylation of the PLC isoform.
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PMID:Angiotensin II stimulates calcineurin activity in proximal tubule epithelia through AT-1 receptor-mediated tyrosine phosphorylation of the PLC-gamma1 isoform. 1208 70

Mechanical stress can induce cardiac hypertrophy through angiotensin II (AngII) type 1 (AT(1)) receptor independently of AngII, however, the intracellular mechanisms remain largely indeterminate. Since calcineurin, a Ca(2+)-dependent phosphatase, plays a critical role in pressure overload-induced cardiac hypertrophy, we therefore, asked whether calcineurin is involved in the AT(1) receptor-mediated but AngII-independent cardiac hypertrophy. Mechanical stretch failed to elicit hypertrophic responses in COS7 cells co-transfected with plasmid of AT(1) receptor and siRNA of calcineurin. Mechanical stresses for 2weeks in vivo and for 24h in vitro significantly induced upregulation of calcineurin expression and hypertrophic responses, such as the increases in cardiomyocytes size and specific gene expressions, in cardiomyocytes of angiotensinogen gene knockout (ATG(-/-)) mice, both of which were significantly suppressed by a specific calcineurin inhibitor FK506, suggesting a critical role of calcineurin in mechanical stress-induced cardiac hypertrophy in the ATG(-/-) mice. Furthermore, an AT(1) receptor blocker Losartan not only attenuated cardiac hypertrophy but also abrogated upregulation of cardiac calcineurin expression induced by mechanical stresses in the AngII-lacking mice, indicating that calcineurin expression is regulated by AT(1) receptor without the involvement of AngII after mechanical stress. These findings collectively suggest that mechanical stress-evoked but AngII-independent activation of AT(1) receptor induces cardiac hypertrophy through calcineurin pathway.
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PMID:Mechanical stress-evoked but angiotensin II-independent activation of angiotensin II type 1 receptor induces cardiac hypertrophy through calcineurin pathway. 2058 Jun 88