Store-independent Orai1/3 channels activated by intracrine leukotriene C4: role in neointimal hyperplasia.
BACKGROUND
Through largely unknown mechanisms, Ca(2+) signaling plays important roles in vascular smooth muscle cell (VSMC) remodeling. Orai1-encoded store-operated Ca(2+) entry has recently emerged as an important player in VSMC remodeling. However, the role of the exclusively mammalian Orai3 protein in native VSMC Ca(2+) entry pathways, its upregulation during VSMC remodeling, and its contribution to neointima formation remain unknown.


OBJECTIVE
The goal of this study was to determine the agonist-evoked Ca(2+) entry pathway contributed by Orai3; Orai3 potential upregulation and role during neointima formation after balloon injury of rat carotid arteries.


RESULTS
Ca(2+) imaging and patch-clamp recordings showed that although the platelet-derived growth factor activates the canonical Ca(2+) release-activated Ca(2+) channels via store depletion in VSMC, the pathophysiological agonist thrombin activates a distinct Ca(2+)-selective channel contributed by Orai1, Orai3, and stromal interacting molecule1 in the same cells. Unexpectedly, Ca(2+) store depletion is not required for activation of Orai1/3 channel by thrombin. Rather, the signal for Orai1/3 channel activation is cytosolic leukotrieneC4 produced downstream thrombin receptor stimulation through the catalytic activity of leukotrieneC4 synthase. Importantly, Orai3 is upregulated in an animal model of VSMC neointimal remodeling, and in vivo Orai3 knockdown inhibits neointima formation.


CONCLUSIONS
These results demonstrate that distinct native Ca(2+)-selective Orai channels are activated by different agonists/pathways and uncover a mechanism whereby leukotrieneC4 acts through hitherto unknown intracrine mode to elicit store-independent Ca(2+) signaling that promotes vascular occlusive disease. Orai3 and Orai3-containing channels provide novel targets for control of VSMC remodeling during vascular injury or disease.
College of Nanoscale Science and Engineering, NFE4417, University at Albany, State University of New York, 257 Fuller Rd, Albany, NY 12203, USA. mtrebak@albany.edu
José C
JC
González-Cobos
Xuexin
X
Zhang
Wei
W
Zhang
Brian
B
Ruhle
Rajender K
RK
Motiani
Rainer
R
Schindl
Martin
M
Muik
Amy M
AM
Spinelli
Jonathan M
JM
Bisaillon
Arti V
AV
Shinde
Marc
M
Fahrner
Harold A
HA
Singer
Khalid
K
Matrougui
Margarida
M
Barroso
Christoph
C
Romanin
Mohamed
M
Trebak
D000800:Angioplasty, Balloon / Q000009:adverse effects; D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D020212:Carotid Artery Injuries / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D003600:Cytosol / Q000378:metabolism; D004195:Disease Models, Animal; D017997:Leukotriene C4 / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000473:pathology / Q000503:physiopathology*; D058426:Neointima / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D000071740:ORAI1 Protein; D018408:Patch-Clamp Techniques; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071737:Stromal Interaction Molecule 1; D013917:Thrombin / Q000378:metabolism / Q000494:pharmacology
D015220:Calcium Channels; D008562:Membrane Glycoproteins; D000071740:ORAI1 Protein; C532493:Orai1 protein, rat; C573659:Orai3 protein, rat; D010982:Platelet-Derived Growth Factor; D034741:RNA, Small Interfering; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D017997:Leukotriene C4; D013917:Thrombin