title: Characterization of calcium signals provoked by lysophosphatidylinositol in human microvascular endothelial cells.
abstract: The lipid molecule, lysophosphatidylinositol (LPI), is hypothesised to form part of a novel lipid signalling system that involves the G protein-coupled receptor GPR55 and distinct intracellular signalling cascades in endothelial cells. This work aimed to study the possible mechanisms involved in LPI-evoked cytosolic Ca(2+) mobilization in human brain microvascular endothelial cells. Changes in intracellular Ca(2+) concentrations were measured using cell population Ca(2+) assay. LPI evoked biphasic elevation of intracellular calcium concentration, a rapid phase and a sustained phase. The rapid phase was attenuated by the inhibitor of PLC (U 73122), inhibitor of IP(3) receptors, 2-APB and the depletor of endoplasmic reticulum Ca(2+) store, thapsigargin. The sustained phase, on the other hand, was enhanced by U 73122 and abolished by the RhoA kinase inhibitor, Y-27632. In conclusion, the Ca(2+) signal evoked by LPI is characterised by a rapid phase of Ca(2+) release from the endoplasmic reticulum, and requires activation of the PLC-IP(3) signalling pathway. The sustained phase mainly depends on RhoA kinase activation. LPI acts as novel lipid signalling molecule in endothelial cells, and elevation of cytosolic Ca(2+) triggered by it may present an important intracellular message required in gene expression and controlling of vascular tone.
authors.affiliation: Department of Pharmacology and Clinical Pharmacy, College of Medicine and Health Sciences, Sultan Qaboos University, Sultanate of Oman. yousufm@squ.edu.om.
authors.forename: Y M
authors.initials: YM
authors.lastname: Al Suleimani
authors.forename: C R
authors.initials: CR
authors.lastname: Hiley
mesh_terms: D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002461:Cell Line, Transformed; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D055806:Microvessels / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D008246:Lysophospholipids; C025449:lysophosphatidylinositol