Reactive oxygen intermediates (ROIs) are involved in the intracellular transduction of angiotensin II signal in C2C12 cells.
Increasing evidence suggests that angiotensin II may act as a growth factor for several muscle cell types. Angiotensin II stimulation activates many immediate early response genes like c-Fos, c-Jun, c-Myc and Egr-1 in both vascular smooth muscle cells and cardiomyocytes, independently of whether a hyperplastic or hypertrophic response is taking place. In this study we report that angiotensin II significantly stimulates AP1-driven transcription in mouse skeletal muscle cells C2C12 stably transfected with a TRE-tk-CAT plasmid in a dose-dependent manner (peak stimulation at 10(-5) M of angiotensin II). Moreover, angiotensin II increases the binding of the AP1 complex to its DNA target in both quiescent C2C12 myoblasts and in differentiated C2C12 myotubes. Most of the TRE-bound complexes in both unstimulated and angiotensin II-treated cells consist of c-jun/c-fos heterodimers. Using a set of different protein kinase inhibitors, including HA1004, H7, tyrphostin, genistein and staurosporine, we could demonstrate that the angiotensin II-induced AP1 binding increase is not mediated by the cAMP-dependent pathway and that protein kinase C and tyrosine kinases are involved. Treatment of C2C12 cells with H2O2 induces a dose-dependent increase in c-jun/c-fos heterodimer binding, specifically reverted by the cysteine derivative and glutathione precursor N-acetyl-L-cysteine (NAC). The observation that the induction by angiotensin II of both the AP1 DNA binding activity and DNA synthesis in quiescent C2C12 myoblasts is abolished by NAC strongly suggests a role for reactive oxygen intermediates (ROIs) in the intracellular transduction of angiotensin II signals for immediate early gene induction and for cell proliferation.
Puri
P L
PL
Fondazione Andrea Cesalpino, University of Rome La Sapienza, Italy.
Avantaggiati
M L
ML
Burgio
V L
VL
Chirillo
P
P
Collepardo
D
D
Natoli
G
G
Balsano
C
C
Levrero
M
M
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects*; D017781:Genes, Immediate-Early / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection
D000975:Antioxidants; D009838:Oligodeoxyribonucleotides; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; D000804:Angiotensin II; D011494:Protein Kinases