Enhanced Activity of Variant Phospholipase C-δ1 Protein (R257H) Detected in Patients With Coronary Artery Spasm

Abstract

Background-We recently demonstrated that phospholipase C (PLC)-␦1 activity in cultured skin fibroblasts obtained from patients with coronary spastic angina (CSA) is enhanced. We tested the hypothesis that structural abnormality in PLC-␦1 isoform is a cause of the enhanced activity. Methods and Results-Sequence analysis of the cDNA coding for PLC-␦1 obtained from fibroblasts revealed that one conversion of guanine to adenine (A) was present at nucleotide position 864 in one CSA patient, resulting in the amino acid replacement of arginine 257 by histidine (R257H). The incidence of 864A/A in genomic DNA, analyzed by single-strand conformation polymorphism, was greater in patients with CSA than in male control subjects (6 of 57 patients with CSA versus 1 of 62 control subjects, PϽ0.05). The activity of the variant PLC-␦1 protein under free calcium concentration between 10 Ϫ8 and 10 Ϫ7 mol/L was 2-fold higher than that of the wild-type protein. Baseline intracellular calcium concentration ([Ca 2ϩ ] i ) in human embryonic kidney 293 cells transfected with the variant PLC-␦1 was higher than that in cells with the wild type. The peak increase in [Ca 2ϩ ] i in response to acetylcholine at 10 Ϫ6 and 10 Ϫ5 mol/L was greater in the cells with the variant PLC-␦1 than in those with the wild type. Conclusions-These findings indicate that the R257H variant in the PLC-␦1 gene detected in patients with CSA is associated with enhancement of enzyme activity, and they describe a novel mechanism for the enhanced coronary vasomotility in

START-GAP/DLC Family Proteins: Molecular Mechanisms for Anti-Tumor Activities

“…Thus, it is conceivable that upregulation of START-GAP1/DLC1 protein observed in patients with CSA is responsible for the high activity of PLCδ1. These results are consistent with the previous finding of the H 257 R variant of PLCδ1, in which the conformational change is associated with upregulation of PLCδ1 activity [120]. These characteristics seem to explain the pathogenesis of CSA in which both the basal vascular tone and the vasoconstrictor response to the diverse stimuli were enhanced.…”

“…It has been known that the PLC activity with its effect on the regulation of intracellular Ca 2+ levels has potential roles in cardiac regulation. PLCδ1 activity has shown to be enhanced in patients with coronary artery spasm, CSA (coronary spastic angina) [119,120]. In this context, a new finding that START-GAP1/DLC1 protein levels and mRNA levels in fibroblasts from Japanese patients with CSA were enhanced compared with levels in control subjects is noteworthy [121].…”

Multi-vessel coronary vasospasm in a patient with excessive inguinal pain

“…Nitrite oxide deficiency increases the susceptibility to potent vasoconstrictor mediators such as angiotensin II and endothelin I. Other precipitating factors are enhanced phospholipase C and Rho kinase activity (4,5). They regulate the intracellular calcium level and cause smooth muscle constriction.…”

Malondialdehyde-Modified Low Density Lipoprotein as Oxidative-Stress Marker in Vasospastic Angina Patients

“…8) It is known that the etiology of VSA involves multiple environmental factors such as smoking, 9,10) alcohol consumption, 11) lipid disorder, 12) abnormal glucose metabolism, 13) psychological stress (abnormal autonomic nervous system function), 14) and genetic factors. [15][16][17] The pathology of VSA is associated with endothelial cell dys-function and hypercontraction of vascular smooth muscle cells (VSMC). Multiple environmental factors are considered to be triggers of coronary spasm.…”