p122 protein enhances intracellular calcium increase to acetylcholine: its possible role in the pathogenesis of coronary spastic angina.
OBJECTIVE
Phospholipase C-δ1 activity is enhanced in patients with coronary artery spasm, and a p122 protein was recently cloned to potentiate phospholipase C-δ1 activity. To investigate the role of p122 in enhanced vasomotility, we examined p122 expression in the cultured skin fibroblasts obtained from patients with and without coronary spasm, intracellular Ca(2+) concentration ([Ca(2+)]i) [corrected] at baseline and after stimulation with acetylcholine in the cells transfected with p122, and promoter in genomic DNA.


RESULTS
[corrected] p122 protein and gene expression levels in patients with coronary spasm (n=11) were enhanced compared with levels in control subjects (n=9) (P<0.01 for both). [Ca(2+)](i) at baseline and the peak increase in [Ca(2+)](i) in response to acetylcholine were both 2 times higher in cells transfected with p122 than in those without p122. Conversely, knockdown of p122 resulted in diminished [Ca(2+)](i) response. In the p122 promoter analysis, the -228G/A and -1466C/T variants revealed the increase in luciferase activity. Although the -1466C/T variant was similar between 144 patients with coronary spasm and 148 controls, the -228G/A variant was more frequent in male patients than in male controls (P<0.05).


CONCLUSIONS
The p122 protein is upregulated in patients with coronary spasm, causing increased [Ca(2+)](i) to acetylcholine, and thereby seems to be related to enhanced coronary vasomotility.
Murakami
Reiichi
R
Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
Osanai
Tomohiro
T
Tomita
Hirofumi
H
Sasaki
Satoko
S
Maruyama
Atsushi
A
Itoh
Ken
K
Homma
Yoshimi
Y
Okumura
Ken
K
D000109:Acetylcholine / Q000494:pharmacology*; D000787:Angina Pectoris / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D016022:Case-Control Studies; D002460:Cell Line; D002478:Cells, Cultured; D003329:Coronary Vasospasm / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D055785:Gene Knockdown Techniques; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008875:Middle Aged; D054803:Phospholipase C delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
C112352:DLC1 protein, human; D017931:DNA Primers; D020690:GTPase-Activating Proteins; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; C518024:PLCD1 protein, human; D054803:Phospholipase C delta; D000109:Acetylcholine; D002118:Calcium