scholarly journals A Critical Role for the Transient Receptor Potential Channel Type 6 in Human Platelet Activation

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0125764 ◽  
Author(s):  
Hari Priya Vemana ◽  
Zubair A. Karim ◽  
Christine Conlon ◽  
Fadi T. Khasawneh
2019 ◽  
Vol 20 ◽  
pp. 100685
Author(s):  
Enma V. Paez Espinosa ◽  
Olivia A. Lin ◽  
Zubair A. Karim ◽  
Fatima Z. Alshbool ◽  
Fadi T. Khasawneh

2009 ◽  
Vol 297 (1) ◽  
pp. H417-H424 ◽  
Author(s):  
Jie Chen ◽  
Randy F. Crossland ◽  
Muzamil M. Z. Noorani ◽  
Sean P. Marrelli

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 μM) and completely inhibited by a TRPC channel inhibitor, La3+ (100 μM). The UTP-stimulated current ( IUTP) 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 IUTP. 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 IUTP. 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 μM) in the presence or absence of La3+ (100 μM) and then evaluated for relaxation to an NO donor, sodium nitroprusside (1 nM to 1 μM). Relaxation to sodium nitroprusside was significantly reduced in the La3+ 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 La3+-sensitive channels consistent with TRPC1/TRPC3.


Author(s):  
Minoru Wakamori ◽  
Takashi Yoshida ◽  
Takashi Kikuchi ◽  
Daisuke Kondoh ◽  
Masashi Komatsu

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3201-3201
Author(s):  
John P Murad ◽  
Harold J Ting ◽  
Fadi T. Khasawneh

Abstract Abstract 3201 In spite of the fact that changes in the intracellular levels of calcium (e.g., calcium entry (CE)) is a central step in platelet activation, the underlying mechanism of this CE is still ill defined. Previous studies have demonstrated that of the transient receptor potential channel (TRPC) family, TRPC1 and, to a higher extent, TRPC6 are expressed in blood platelets, whereas TRPC4 is found in megakaryocytes (at the mRNA level). Furthermore, recent studies have shown that TRPC1 deficient platelets exhibited no defects in platelet function, and unaltered calcium homeostasis. Based on these considerations, we hypothesized that TRPC6 plays an essential role in receptor-operated calcium entry and platelet function. Our preliminary studies reveal that platelets deficient in TRPC6 exhibited a defect in platelet aggregation mediated by the thromboxane receptor (TPR), at least, at low agonist levels (i.e., low levels of receptor activation). Moreover, TRPC6 deficient mice also exhibited a significantly prolonged bleeding time, and were protected against thrombosis development, using a FeCl3 carotid-artery injury model. Together, these findings are consistent with the role of TPRs in hemostasis and the genesis of thrombosis. In future studies, we will investigate the role of TRPC6 in: 1. calcium homeostasis; 2. separate platelet functional responses such as dense granule secretion and shape change; and 3. in platelet activation via separate platelet G-protein coupled receptors such as PAR4 and P2Y1. These studies may define a new therapeutic target for managing multiple thrombosis-based disorders. Disclosures: No relevant conflicts of interest to declare.


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