Abstract
We previously reported that intracellular Ca2+ increased transiently in response to stretch through the activation of mechanosensitive (MS) cation channel in human umbilical vein endothelial cells (HUVEC). However, neither the identity nor the mechanism of activation of the plasma membrane influx pathway that mediates stretch-induced change in [Ca2+]i is known. Since HUVEC expresses several types of mechanosensitive TRP channels including TRPV2, we examined the effects of the targeting suppression of TRPV2 protein expression in HUVEC using TRPV2-specific morphorino-oligo. Western blot analysis and immunocytochemical staining confirmed that TRPV2 was efficiently knocked down by transfection with the morphorino-oligo. In these cells, the stretch induced Ca2+ increase measured by fluorescence imaging using fura2 was completely abolished. After the cells were subjected to 20% uni-axial cyclic stretch at 1Hz for 1h, neither a stretch-enhanced stress fiber formation nor a shift in the cell orientation transverse to the strain direction could not be observed. Finally, TRPV2-knocked down HUVEC did not show stretch-induced NO production. These observations strongly suggest that TRPV2 is a responsible ion channel for stretch-induced Ca2+ increase, which leads the cytoskeletal reorganization and NO production in HUVEC. Thus, TRPV2 would be a key component of MS channel complex in HUVEC. Furthermore, the result that the production of vasorelaxing factor NO depends on TRPV2 suggests that TRPV2 is involved in hypertrophic heart disease caused by change in blood pressure. [J Physiol Sci. 2008;58 Suppl:S79]
