Endothelin-1 induces hypertrophy with enhanced expression of muscle-specific genes in cultured neonatal rat cardiomyocytes.
To determine whether endothelin-1 (ET-1) induces hypertrophy of cardiomyocytes, the effects of ET-1 on the expression of muscle-specific genes and a proto-oncogene, c-fos, in cultured neonatal rat cardiomyocytes were examined by Northern blot analysis. ET-1 (10(-7) M) induced about twofold to fourfold increases in the gene expression of myosin light chain 2, alpha-actin, and troponin I after 6 hours, which continued up to 24 hours. The ET-1-induced increases in mRNA levels for these muscle-specific genes were dose dependent (10(-9) to 10(-7) M). Run-on transcriptional assay showed that the changes in mRNA level for three muscle-specific genes were regulated, at least in part, at the transcriptional level. 12-O-Tetradecanoylphorbol 13-acetate (TPA), a potent protein kinase C activator, and the Ca2+ ionophore ionomycin also increased mRNA levels of three muscle-specific genes. ET-1, TPA, and ionomycin similarly induced the expression of c-fos after 30 minutes, which returned to an undetectable level after 6 hours. ET-1 remarkably and dose-dependently stimulated accumulation of total inositol phosphates in cardiomyocytes. Morphometrical evaluation showed that ET-1 significantly increased surface area of cardiomyocytes without cell proliferation. ET-1 also dose-dependently stimulated the synthesis of protein and DNA, which was unaffected by the L-type calcium channel blocker nicardipine. These data suggest that ET-1 induces hypertrophy of cardiomyocytes associated with the induction of muscle-specific gene transcripts through the possible involvement of protein kinase C activation or intracellular Ca2+ mobilization.
Ito
H
H
Second Department of Medicine, Tokyo Medical and Dental University, Japan.
Hirata
Y
Y
Hiroe
M
M
Tsujino
M
M
Adachi
S
S
Takamoto
T
T
Nitta
M
M
Taniguchi
K
K
Marumo
F
F
D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D016232:Endothelins / Q000494:pharmacology*; D005786:Gene Expression Regulation; D006984:Hypertrophy; D007295:Inositol Phosphates / Q000096:biosynthesis; D015759:Ionomycin / Q000494:pharmacology; D007930:Leucine / Q000493:pharmacokinetics; D009132:Muscles / Q000502:physiology*; D009206:Myocardium / Q000473:pathology*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D016232:Endothelins; D007295:Inositol Phosphates; D015759:Ionomycin; D004247:DNA; D007930:Leucine; D013755:Tetradecanoylphorbol Acetate