Src-kinase mediates angiotensin II-induced potentiation in TRPV4 agonist-evoked calcium transients in hypothalamic immortalized neuronal cell line 4B (860.25)

We have previously demonstrated that in bile duct ligated rats, an animal model of inappropriate vasopressin (AVP) release, TRPV4 protein expression and membrane trafficking is increased in AVP neurons. Here, we used an in vitro approach with an immortalized neuronal AVP expressing cell line (4B neurons) to investigate the possible regulation of TRPV4 by angiotensin II (Ang II). We characterized the presence of TRPV4 mRNA and protein in 4B cells. After Ang II (100nM;1 hr) treatment significantly increased TRPV4 levels in crude membrane fractions (p<0.001) and tyrosine phosphorylation of TRPV4 (p<0.001). Using calcium sensitive dye Fura-2AM, we noted that Ang II treated cells exhibited increased calcium transients in response to TRPV4 agonist, GSK1016790A (20nM, p<0.05). This increase was blocked by the Losartan (Ang II receptor antagonist) and Src-kinase inhibitor, PP2, but not by its analog PP3. Our data indicate that Ang II may alter the phosphorylation status of TRPV4 through Src-kinases.Grant Funding ...