Activation of phospholipase C gamma 1 protects renal arteriolar VSMCs from H2O2-induced cell death.
BACKGROUND
We evaluated the effect of hydrogen peroxide (H2O2) on viability of vascular smooth muscle cells (VSMCs) of renal resistance arterioles and determined whether responses are modulated by activation of PLCgamma1.


METHODS
Phospholipase C (PLC)-isozyme protein levels and activity were measured using Western blot analysis and enzymatic production of phosphoinositol 1,4,5-trisphosphate (IP3), respectively. Stimulation of PLCgamma1 was assessed by immunoblots of tyrosine phosphorylation.


RESULTS
Cytotoxicity of H2O2 exposure was concentration-dependent (30% death with 250 microM; 87% with 500 microM at 8 h) and time-dependent (7% at 1 h; 30% at 8 h with 250 microM H2O2. Catalase abolished such relations. H2O2 increased PLCgamma1 expression more than that of PLCdelta1 and almost doubled total PLC enzymatic activity between 2 and 8 h, changes prevented by catalase. The PLC inhibitor U73112 (3 microM) enhanced the cytotoxic concentration and time effects of H2O2. In acute studies, H2O2 rapidly caused tyrosine phosphorylation of PLCgamma1.


CONCLUSIONS
H2O2 increased PLCgamma1 expression and almost doubled total PLC activity, changes abolished by catalase. We conclude that H2O2 is cytotoxic to cultured VSMCs of renal preglomerular arterioles, a process that is attenuated by compensatory increases in PLCgamma1 protein level, tyrosine phosphorylation of PLCgamma1 and PLC enzymatic activity to generate IP3.
Peng
Zhangping
Z
Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7545, USA.
Arendshorst
William J
WJ
D000818:Animals; D001160:Arterioles / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007668:Kidney / Q000098:blood supply* / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D009131:Muscle, Smooth, Vascular / Q000098:blood supply* / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D051966:Phospholipase C gamma / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D006861:Hydrogen Peroxide; D051966:Phospholipase C gamma