Role of TGF-beta1 in vascular smooth muscle cell apoptosis induced by angiotensin II.
Both Angiotensin II and transforming growth factor beta-1 (TGF-beta1) are important mediators of vascular smooth muscle cell function and have been reported to mediate the balance between proliferation and apoptosis. Some crosstalk between Angiotensin II and TGF-beta1 in end-organ hypertension has been established. However, whether TGF-beta1 is able to mediate Angiotensin II-induced vascular cell damage remains unknown. Vascular smooth muscle cells were obtained from rat thoracic aorta and cultured in 10% foetal calf serum. In all experiments, medium was changed to a low-serum (0.4% foetal calf serum) or serum-free one with or without Angiotensin II. Apoptosis was assessed by DNA fragmentation, DNA synthesis was measured as bromo-deoxyuridine uptake. TGF-beta1 production was determined by Enzyme-linked Immunosorbent Assay (ELISA) from cell conditioned media, RT-PCR from cell lysates and confocal immunostaining of fixed cells. Angiotensin II induced apoptosis in the absence of DNA synthesis when coincubated at 1 microM. Neither the specific anti-TGF-beta1 monoclonal antibody (50 microg/ml) nor the novel activin-like kinase (ALK)-4/5/7 synthetic inhibitor SB-431542 (4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide) at 10 microM were able to inhibit this effect. Angiotensin II induced expression of TGF-beta1 without further secretion of this cytokine. This effect was not affected by incubation with the AT1 inhibitor irbesartan (10 microM). A pharmacological approach to TGF-beta1 inhibition would be unable to reverse the apoptotic effect of Angiotensin II on vascular smooth muscle cells.
Redondo
Santiago
S
Department of Pharmacology, School of Medicine, Universidad Complutense, Av. Complutense s/n, 28040 Madrid, Spain.
Ruiz
Emilio
E
Padilla
Eugenia
E
Gordillo-Moscoso
Antonio
A
Tejerina
Teresa
T
D029404:Activin Receptors / Q000037:antagonists & inhibitors; D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001549:Benzamides / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004149:Dioxoles / Q000494:pharmacology; D000077405:Irbesartan; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology; D051381:Rats; D011921:Rats, Inbred WKY; D013777:Tetrazoles / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000502:physiology*
C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D047228:Angiotensin II Type 1 Receptor Blockers; D001549:Benzamides; D001713:Biphenyl Compounds; D004149:Dioxoles; D013777:Tetrazoles; D053773:Transforming Growth Factor beta1; D000804:Angiotensin II; D029404:Activin Receptors; D000077405:Irbesartan