Sustained contraction and loss of NO production in TGFbeta1-treated endothelial cells.
OBJECTIVE
Transforming growth factor beta1 (TGFbeta1) is generated in atherosclerotic and injured vessel walls. We examined whether the endothelial-to-mesenchymal transdifferentiation induced by TGFbeta1 affects endothelial functions.


METHODS
Bovine aortic endothelial cells (BAECs) were treated with 3 ng ml(-1) TGFbeta1 for 7 days. Contraction of TGFbeta1-treated BAECs was assessed by collagen gel contraction assay. Protein expression and phosphorylation were assessed by Western blotting. Intracellular Ca2+ concentration and NO production were measured using fura2 and DAF-2, respectively.


RESULTS
TGFbeta1-treated BAECs showed dense actin fibers and expressed smooth muscle marker proteins; they also changed into smooth muscle-like, spindle-shaped cells in collagen gel cultures. ATP (10 microM) induced a gradual contraction of collagen gels containing TGFbeta1-treated BAECs but not of gels containing control BAECs. ATP-induced contraction of TGFbeta1-treated BAECs was not reversed by the removal of ATP but was partially suppressed by a high concentration of sodium nitroprusside (1 microM). TGFbeta1-treated BAECs showed sustained phosphorylation of myosin light chain in response to ATP and low levels of basal MYPT1 expression. ATP-induced Ca2+ transients as well as eNOS protein expression were not affected by TGFbeta1 in BAECs. However, ATP-induced NO production was significantly reduced in TGFbeta1-treated BAECs. Anti-TGFbeta1 antibody abolished all of these TGFbeta1-induced changes in BAECs.


CONCLUSIONS
Mesenchymal transdifferentiation induced by TGFbeta1 leads to sustained contraction and reduced NO production in endothelial cells. Such effects, therefore, would not be beneficial for vascular integrity.
Watanabe
M
M
Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Oike
M
M
Ohta
Y
Y
Nawata
H
H
Ito
Y
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D032342:Muscle Cells / Q000187:drug effects* / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects*; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000378:metabolism; D010766:Phosphorylation; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology
D008840:Microfilament Proteins; D018994:Myosin Light Chains; D053773:Transforming Growth Factor beta1; D009569:Nitric Oxide; D043263:Myosin-Light-Chain Phosphatase; D002118:Calcium