EC:2.7.11.12 - FACTA Search

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)

We tested the hypotheses that the NO-cGMP-PKG pathway mediates inhibition of the store-operated cation channel (SOC) in human glomerular mesangial cells (HMC) and that TRPC4, a molecular component of SOC in HMC, is associated with PKG-phosphorylated vasodilator-stimulated phosphoprotein (VASP). Using fura 2 ratiometry, we measured intracellular Ca(2+) concentration [Ca(2+)](i) to determine whether sodium nitroprusside (SNP), an NO donor, and 8-Br-cGMP affected SOC-TRPC4 via PKG. We found that the SOC response in HMC was attenuated in the presence of 100 microM SNP, an NO donor, or 100 microM 8-Br-cGMP. Addition of DT-3 (2.5 microM), a specific PKG-1alpha inhibitor, reversed the effects of 8-Br-cGMP on the SOC response. Application of 100 microM cAMP did not significantly inhibit the SOC response. RT-PCR and Western blotting revealed PKG-1alpha transcript and protein in HMC. Immunocytochemical analysis localized PKG-1alpha to the cytoplasm and plasma membrane of HMC. Previous studies have shown that PKG-mediated phosphorylation of VASP attenuates cellular Ca(2+) entry, resulting in altered growth and proliferation. Therefore, we used Western blotting and immunocytochemistry to determine whether PKG-phosphorylated VASP associates with TRPC4. Western blot analysis revealed that 8-Br-cGMP enhanced the phosphorylation of VASP at serine 239 (Ser239), a known PKG phosphorylation site, in HMC within 5 min. Coimmunoprecipitation and coimmunostaining showed that P-Ser239-VASP associated with TRPC4. However, VASP that was unphosphorylated at Ser239 was not associated with TRPC4. These results indicate that VASP has a role in the NO/PKG-1alpha-mediated inhibition of the TRPC4-SOC response in HMC.
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PMID:Association of VASP with TRPC4 in PKG-mediated inhibition of the store-operated calcium response in mesangial cells. 1791 34

Nitric oxide (NO) inhibits transient receptor potential channel 3 (TRPC3) channels via a PKG-dependent mechanism. We sought to determine 1) whether NO inhibition of TRPC3 occurs in freshly isolated smooth muscle cells (SMC); and 2) whether NO inhibition of TRPC3 channels contributes to NO-mediated vasorelaxation. We tested these hypotheses in freshly isolated rat carotid artery (CA) SMC using patch clamp and in intact CA by vessel myograph. We demonstrated TRPC3 expression in whole CA (mRNA and protein) that was localized to the smooth muscle layers. TRPC1 protein was also expressed and coimmunoprecipitated with TRPC3. Whole cell patch clamp demonstrated nonselective cation channel currents that were activated by UTP (60 microM) and completely inhibited by a TRPC channel inhibitor, La(3+) (100 microM). The UTP-stimulated current (I(UTP)) was also inhibited by intracellular application of anti-TRPC3 or anti-TRPC1 antibody, but not by anti-TRPC6 or anti-TRPC4 control antibodies. We next evaluated the NO signaling pathway on I(UTP). Exogenous NO [(Z)-1-{N-methyl-N-[6(N-methylammoniohexyl)amino]}diazen-1-ium-1,2-diolate (MAHMA NONOate)] or a cell-permeable cGMP analog (8-bromo-cGMP) significantly inhibited I(UTP). Preapplication of a PKG inhibitor (KT5823) reversed the inhibition of MAHMA NONOate or 8-bromo-cGMP, demonstrating the critical role of PKG in NO inhibition of TRPC1/TRPC3. Intact CA segments were contracted with UTP (100 microM) in the presence or absence of La(3+) (100 microM) and then evaluated for relaxation to an NO donor, sodium nitroprusside (1 nM to 1 microM). Relaxation to sodium nitroprusside was significantly reduced in the La(3+) treatment group. We conclude that freshly isolated SMC express TRPC1/TRPC3 channels and that these channels are inhibited by NO/cGMP/PKG. Furthermore, NO contributes to vasorelaxation by inhibition of La(3+)-sensitive channels consistent with TRPC1/TRPC3.
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PMID:Inhibition of TRPC1/TRPC3 by PKG contributes to NO-mediated vasorelaxation. 1950 52

The transient receptor potential (TRP) protein superfamily consists of a diverse group of cation channels that bear structural similarities to the fruit fly Drosophila TRP. The TRP superfamily is distinct from other groups of ion channels in displaying a large diversity in ion selectivity, modes of activation, and physiological functions. Classical TRP (transient receptor potential canonical (TRPC)) channels are activated by stimulation of Gq-PLC-coupled receptors and modulated by phosphorylation. The cyclic guanosine monophosphate (cGMP)-PKG pathway is involved in the regulation of TRPC3 and TRPC6 channels. Phosphodiesterase (PDE) 5 inhibitor induced muscle relaxation in corporal smooth muscle cells and was used to treat erectile dysfunction by inhibiting cGMP degradation. Here, we report the functional relationship between TRPC4 and cGMP. In human embryonic kidney (HEK) 293 cells overexpressing TRPC4, cGMP selectively activated TRPC4 channels and increased cytosolic calcium level through TRPC4 channel. We investigated phosphorylation sites in TRPC4 channels and identified S688 as an important phosphorylation site for the cGMP-PKG pathway. Cyclic GMP also activated TRPC4-like current with doubly rectifying current-voltage relationship in prostate smooth muscle cell lines. Taken together, these results show that TRPC4 is phosphorylated by the cGMP-PKG pathway and might be an important target for modulating prostate function by PDE5 inhibitors.
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PMID:The regulation of transient receptor potential canonical 4 (TRPC4) channel by phosphodiesterase 5 inhibitor via the cyclic guanosine 3'5'-monophosphate. 2812 39

TRPC channels have been suggested as potential candidates mediating store-operated Ca²⁺ entry (SOCE) in cardiomyocytes. There is increasing evidence that the TRPC isoforms TRPC1 and TRPC4 might fulfill the function as SOCs, in concert with or in parallel to the key players of SOCE, Orai1, and STIM1. Several other isoforms, e.g., TRPC3, TRPC6, and TRPC7, might rather associate to receptor-activated diacylglycerol (DAG)-sensitive ion channels. However, the exact activation mode has not been elucidated yet, given the characteristic of TRPC channels to heteromerize to unpredictable ion channel assemblies. Despite the incomplete information about TRPC activation, there is common agreement that they are crucial Ca²⁺ components in cardiac signaling and disease. All TRPC isoforms, TRPC1, TRPC3, TRPC4, TRPC5, TRPC6, and TRPC7, are differentially regulated in cardiac disease, and nearly all of them have been shown to impact cardiac signaling pathways that accelerate cardiac disease development. In particular, the calcineurin-nuclear factor of activated T-cell (NFAT) signaling pathway has repeatedly been linked to a TRPC-dependent Ca²⁺ influx in cardiomyocytes. Moreover, the protein kinases PKG and PKC have been found to modulate TRPC function and the hypertrophic response. Other signaling molecules, such as the serine/threonine kinase Ca²⁺/calmodulin-dependent protein kinase II (CamKII) or the oxidative stress molecule, NADPH oxidase 2 (NOX2), have also been related to TRPC-dependent effects in the heart.The present chapter provides a comprehensive overview of TRPC channels as Ca²⁺ entities in cardiomyocytes, their interplay with Ca²⁺ signaling pathways, and role in cardiac pathology.
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PMID:Cardiac Remodeling and Disease: SOCE and TRPC Signaling in Cardiac Pathology. 2890 Sep 30