Urotensin-II signaling mechanism in rat coronary artery: role of STIM1 and Orai1-dependent store operated calcium influx in vasoconstriction.
OBJECTIVE
Human urotensin-II (UII) is considered the most potentendogenous vasoconstrictor discovered to date, although the precise mechanism activated downstream of its receptor UTS2R in blood vessels remains elusive. The aim of this study was to determine the role of the store operated Ca(2+) entry (SOCE) signaling pathway in UII-induced coronary artery vasoconstriction.


RESULTS
We used a combination of isometric tension measurement, Ca(2+) imaging, pharmacology, and molecular approaches to study UII-mediated rat coronary artery vasoconstriction and intracellular Ca(2+) mobilization in coronary smooth muscle cells. We found that UII promoted dose-dependent vasoconstriction and elicited Ca(2+) and Mn(2+) influx, which were sensitive to classical SOCE inhibitors. In addition, knockdown of either STIM1 or Orai1 essentially inhibited UII-mediated SOCE and prevented UII but not high-KCL evoked contraction in transfected coronary artery. Moreover, we found that Ca(2+)-independent phospholipase A(2)β was involved in UII effects and that is colocalized with STIM1 in different submembrane compartments. Importantly, STIM1 but not Orai1 downregulation inhibits significantly independent phospholipase A(2) activation. Furthermore, lysophosphatidylcholine, an independent phospholipase A(2) product, activated Orai1 but not STIM1-dependent contraction and SOCE.


CONCLUSIONS
Here, we demonstrated that different critical players of SOCE signaling pathway are required for UII-induced vasoconstriction of rat coronary artery.
Group of Cardiovascular Physiopathology, Universidad de Extremadura, Cáceres, Spain.
Alejandro
A
Domínguez-Rodríguez
Ignacio
I
Díaz
María
M
Rodríguez-Moyano
Eva
E
Calderón-Sánchez
Juan Antonio
JA
Rosado
Antonio
A
Ordóñez
Tarik
T
Smani
D000818:Animals; D001692:Biological Transport / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D000071740:ORAI1 Protein; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D000071737:Stromal Interaction Molecule 1; D014579:Urotensins / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D008562:Membrane Glycoproteins; D000071740:ORAI1 Protein; C532493:Orai1 protein, rat; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D014579:Urotensins; C029677:urotensin II; D002118:Calcium