Endothelial cells line the wall of all blood vessels and regulate a wide variety of functions, including contractility which controls systemic blood pressure. Dysfunctional endothelial cells are a hallmark of several cardiovascular diseases, but pathological mechanisms involved are poorly understood. Endothelial cells express both PKD1 (polycystin-1), an eleven transmembrane domain protein, and PKD2 (polycystin-2), a transient receptor potential (TRP) channel. Regulatory mechanisms, physiological functions and pathological involvement during hypertension of PKD1 protein and PKD2 channels in endothelial cells are unclear. Using a wide variety of approaches and inducible, endothelial cell-specific knockout mice, we provide evidence that physical coupling of PKD1 to PKD2 in endothelial cells stimulates vasodilation. Preliminary data also suggest that PKD1/PKD2 channel signaling is dysfunctional during hypertension, which attenuates this vasodilatory signaling mechanism. In this proposal, we will investigate three specific aims.
Aim 1 will test the hypothesis that endothelial-dependent physiological stimuli activate PKD1/PKD2 coupling in endothelial cells, leading to vasodilation.
Aim 2 will investigate the mechanisms by which endothelial-dependent stimuli activate PKD1/PKD2 channels in endothelial cells to produce vasodilation.
Aim 3 will study the hypothesis that hypertension is associated with pathological alterations in PKD1/PKD2 channel signaling in endothelial cells that inhibits vasodilation mediated by these proteins. Methods used will include RT-PCR, Western blotting, biotinylation, FRET, RNAi, co-IP, immunofluorescence, patch-clamp electrophysiology, membrane potential recording, intracellular Ca2+ imaging, arterial myography and blood pressure telemetry. This project will provide significant novel information concerning vasoregulation by endothelial cell PKD1 and PKD2 proteins.
Endothelial cells regulate arterial contractility. Dysfunctional endothelial cell control of contractility is a hallmark of several cardiovascular diseases, including hypertension, but pathological mechanisms involved are poorly understood. We will investigate the novel hypothesis that PKD1 and PKD2 proteins regulate arterial contractility, investigate signaling mechanisms involved and test the concept that vasodilation mediated through these pathways is dysfunctional during hypertension.
