Endothelin-1-induced phospholipase C-beta and D and protein kinase C isoenzyme signaling leading to hypertrophy in rat cardiomyocytes.
We have previously demonstrated that stimulation of cultured rat neonatal cardiomyocytes by endothelin-1 (ET-1) induces rapid activation of phospholipase C-beta (PLC-beta), accompanied by transient expression of proto-oncogenes and subsequent development of hypertrophy and characteristic phenotypic changes. In the present study we examined the ET-1-induced hypertrophic response in relation to the initial signaling by phospholipase D (PLD) and protein kinase C (PKC). ET-1 (10(-8) M) induced hypertrophy after 48 h, as judged by protein/DNA ratio. The formation (0.5 h) of 14C-labeled phosphatidylethanol ([14C]PEth) in the presence of exogenous ethanol (0.5%) in [14C]palmitate prelabeled cells, which reflects the PLD activity, was increased 1.9- and 5.6-fold by ET-1 and phorbolester (PMA, 10(-6) M), respectively. The translocation of PKC isoforms from the cytosol to the membrane fraction was examined by immunoblot analysis using specific antibodies for PKC-alpha and -epsilon. ET-1 caused a rapid (within 15 s) and sustained disappearance of PKC-epsilon but not of PKC-alpha, from the cytosol. The translocation of PKC-epsilon to the membrane fraction was just detectable. However, PMA (10(-7) M) showed a rapid, sustained, and clearly detectable translocation of PKC-alpha and PKC-epsilon. The results indicate that the ET-1-induced development of hypertrophy via activation of distinct PKC isoenzymes may be initiated not only by PLC-beta but also by PLD signaling.
Lamers
J M
JM
Department of Biochemistry, Cardiovascular Research Institute COEUR, Faculty of Medicine and Health Sciences, Erasmus University Rotterdam, The Netherlands.
Eskildsen-Helmond
Y E
YE
Resink
A M
AM
de Jonge
H W
HW
Bezstarosti
K
K
Sharma
H S
HS
van Heugten
H A
HA
D000818:Animals; D006332:Cardiomegaly / Q000209:etiology*; D002478:Cells, Cultured; D016232:Endothelins / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D007527:Isoenzymes / Q000502:physiology*; D010739:Phospholipase D / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D010738:Type C Phospholipases / Q000502:physiology*
D016232:Endothelins; D007527:Isoenzymes; D011493:Protein Kinase C; D010738:Type C Phospholipases; D010739:Phospholipase D