Mechanical strain increases expression of the brain natriuretic peptide gene in rat cardiac myocytes.
Using a device that applies cyclical strain (1 Hz) to ventricular cardiocytes cultured on collagen-coated silicone elastomer surfaces, we have demonstrated strain-dependent increases in brain natriuretic peptide (BNP) secretion, BNP mRNA levels, and expression of a transiently transfected -1595 human BNP-luciferase reporter. When actinomycin D (10 microM) was introduced concomitantly with the strain stimulus, the strain-induced increase in BNP mRNA was eliminated, and the decay of transcripts was identical in the control and strained cells, indicating the lack of independent effects on transcript stability. Strain-dependent -1595 human BNP-luciferase activity was completely inhibited by chelerythrine, 2-aminopurine, genistein, and W-7 and only partially or not at all by KN-62, wortmannin, and H-89. The effects of these individual agents paralleled their effects on mitogen-activated protein kinase (MAPK) activity, but not c-Jun N-terminal kinase (JNK) activity, in the cells. Overexpression of wild-type MAPK and, to a lesser extent, JNK increased strain-dependent BNP promoter activity, whereas dominant-negative mutants of MAPK kinase, JNK kinase, or Ras completely blocked strain-dependent reporter activity. These findings provide the first demonstration that mechanical strain can increase myocardial gene expression through a transcriptional mechanism and suggest important roles for MAPK and JNK in mediating this effect.
Liang
F
F
Metabolic Research Unit and the Department of Medicine, University of California, San Francisco, California 94143, USA.
Wu
J
J
Garami
M
M
Gardner
D G
DG
D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D008156:Luciferases / Q000235:genetics; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010812:Physical Stimulation; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013312:Stress, Physiological / Q000378:metabolism*; D014158:Transcription, Genetic
D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D020097:Natriuretic Peptide, Brain; D008156:Luciferases; D011494:Protein Kinases