INVOLVEMENT OF CALCIUM-INDEPENDENT PHOSPHOLIPASE A2? IN HIGH GLUCOSE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We report here that calcium-independent phospholipase A2¿ (iPLA2¿) plays a critical role in high glucose-induced RhoA/Rho-kinase/CPI-17 activation and diabetes-associated vascular smooth muscle hypercontractility. First, we show that high glucose increases iPLA2¿ protein expression and enzymatic activity in VSMC. Moreover, activation of iPLA2¿ precedes high glucose-induced CPI-17 activation. Second, using three independent approaches (pharmacological inhibition, genetic deletion, and adenoviral-mediated functional restoration), we illustrate that iPLA2¿ is essential for high glucose-induced CPI-17 phosphorylation. Third, we demonstrate that lipoxygenases, and particularly 15-lipoxygenases, are selectively involved in high glucose-induced and iPLA2¿-mediated CPI-17 phosphorylation. Fourth, we show that iPLA2¿ is required for high glucose-induced RhoA and Rho-kinase activation. Interestingly, we find that PKC is required for high glucose-induced iPLA2¿ protein upregulation.