PIEZO1 and PECAM1 interact at cell-cell junctions and partner in endothelial force sensing.

Two prominent concepts for the sensing of shear stress by endothelium are the PIEZO1 channel as a mediator of mechanically activated calcium ion entry and the PECAM1 cell adhesion molecule as the apex of a triad with CDH5 and VGFR2. Here, we investigated if there is a relationship. By inserting a non-disruptive tag in native PIEZO1 of mice, we reveal in situ overlap of PIEZO1 with PECAM1.

Improved PIEZO1 agonism through 4-benzoic acid modification of Yoda1.

Background And Purpose: The protein PIEZO1 forms mechanically activated, calcium-permeable, non-selective cation channels in numerous cell types from several species. Options for pharmacological modulation are limited and so we modified a small-molecule agonist at PIEZO1 channels (Yoda1) to increase the ability to modulate these channels.

Experimental Approach: Medicinal chemistry generated Yoda1 analogues that were tested in intracellular calcium and patch-clamp assays on cultured cells exogenously expressing human or mouse PIEZO1 or mouse PIEZO2.

Modeling of full-length Piezo1 suggests importance of the proximal N-terminus for dome structure.

Piezo1 forms a mechanically activated calcium-permeable nonselective cation channel that is functionally important in many cell types. Structural data exist for C-terminal regions, but we lack information about N-terminal regions and how the entire channel interacts with the lipid bilayer. Here, we use computational approaches to predict the three-dimensional structure of the full-length Piezo1 and simulate it in an asymmetric membrane.

Synergistic interplay of Gβγ and phosphatidylinositol 4,5-bisphosphate dictates Kv7.4 channel activity.

Kv7.4 channels are key determinants of arterial contractility and cochlear mechanosensation that, like all Kv7 channels, have an obligatory requirement for phosphatidylinositol 4,5-bisphosphate (PIP). βγ G proteins (Gβγ) have been identified as novel positive regulators of Kv7.

MicroRNA-153 targeting of KCNQ4 contributes to vascular dysfunction in hypertension.

Aims: Kv7.4, a voltage-dependent potassium channel expressed throughout the vasculature, controls arterial contraction and is compromised in hypertension by an unknown mechanism. MicroRNAs (miRs) are post-transcriptional regulators of protein production and are altered in disease states such as hypertension.

G-protein βγ subunits are positive regulators of Kv7.4 and native vascular Kv7 channel activity.

Kv7.4 channels are a crucial determinant of arterial diameter both at rest and in response to endogenous vasodilators. However, nothing is known about the factors that ensure effective activity of these channels.

ATP-evoked sustained vasoconstrictions mediated by heteromeric P2X1/4 receptors in cerebral arteries.

Background And Purpose: Current knowledge states that vasoconstrictor responses to ATP are mediated by rapidly desensitizing ligand-gated P2X1 receptors in vascular smooth muscle cells (VSMCs). However, ATP is implicated in contributing to pathological conditions involving sustained vasoconstrictor response such as cerebral vasospasm. The purpose of this study is to test the hypothesis that the stimulation of VSMC P2XR receptors (P2XRs) contributes to ATP-evoked sustained vasoconstrictions in rat middle cerebral arteries (RMCAs).

Vascular smooth muscle cells from small human omental arteries express P2X1 and P2X4 receptor subunits.

Stimulation of P2X receptors by ATP in vascular smooth muscle cells (VSMCs) is proposed to mediate vascular tone. However, understanding of P2X receptor-mediated actions in human blood vessels is limited, and therefore, the current work investigates the role of P2X receptors in freshly isolated small human gastro-omental arteries (HGOAs). Expression of P2X1 and P2X4 receptor subunit messenger RNA (mRNA) and protein was identified in individual HGOA VSMCs using RT-PCR and immunofluorescent analysis and using Western blot in multi-cellular preparations.

Characterization of transcriptional and posttranscriptional properties of native and cultured phenotypically modulated vascular smooth muscle cells.

Various in vitro models are used for studying phenotypic modulation of vascular smooth muscle cells (VSMCs) and the established culture of vascular smooth muscle cells (cVSMCs) is most often used for this purpose. On the other hand, vascular interstitial cells (VICs) are native phenotypically modulated VSMCs present in blood vessels under normal physiological conditions. The aim of this work has been to compare the difference in expression of a number of VSMC-specific markers, which are commonly used for the characterisation of phenotypic modulation of VSMCs, between freshly dispersed VSMCs, VICs and cVSMCs from rat abdominal aorta.

Ca2+ entry following P2X receptor activation induces IP3 receptor-mediated Ca2+ release in myocytes from small renal arteries.

Background And Purpose: P2X receptors mediate sympathetic control and autoregulation of the renal circulation triggering contraction of renal vascular smooth muscle cells (RVSMCs) via an elevation of intracellular Ca(2+) concentration ([Ca(2+) ](i) ). Although it is well-appreciated that the myocyte Ca(2+) signalling system is composed of microdomains, little is known about the structure of the [Ca(2+) ](i) responses induced by P2X receptor stimulation in vascular myocytes.

Experimental Approaches: Using confocal microscopy, perforated-patch electrical recordings, immuno-/organelle-specific staining, flash photolysis and RT-PCR analysis we explored, at the subcellular level, the Ca(2+) signalling system engaged in RVSMCs on stimulation of P2X receptors with the selective agonist αβ-methylene ATP (αβ-meATP).

Purinoreceptor-mediated current in myocytes from renal resistance arteries.

Background And Purpose: Ionotropic purinoreceptors (P2X) in renal vascular smooth muscle cells (RVSMCs) are involved in mediating the sympathetic control and paracrine regulation of renal blood flow (RBF). Activation of P2X receptors elevates [Ca(2+)](i) in RVSMCs triggering their contraction, leading to renal vasoconstriction and decrease of RBF. The goal of the present work was to characterize the P2X receptor-mediated ionic current (I(P2X)) and to identify the types of P2X receptors expressed in myocytes isolated from interlobar and arcuate arteries of rat kidney.

Close relation of arterial ICC-like cells to the contractile phenotype of vascular smooth muscle cell.

This work aimed to establish the lineage of cells similar to the interstitial cells of Cajal (ICC), the arterial ICC-like (AIL) cells, which have recently been described in resistance arteries, and to study their location in the artery wall. Segments of guinea-pig mesenteric arteries and single AIL cells freshly isolated from them were used. Confocal imaging of immunostained cells or segments and electron microscopy of artery segments were used to test for the presence and cellular localization of selected markers, and to localize AIL cells in intact artery segments.

Function of interstitial cells of Cajal in the rabbit portal vein.

Interstitial cells of Cajal (ICCs) were identified in the intact fixed media of the rabbit portal vein (RPV) using c-kit staining. The following experiments were performed using single cell preparations of the enzyme-dispersed vessel. Surviving contacts between the processes of single ICCs and the bodies of smooth muscle cells (SMCs) were observed in electron micrographs and by confocal microscopy.