Objective-We investigated the comparative roles of mitogen-activated protein (MAP) kinases, including c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38, in vascular smooth muscle cell (VSMC) proliferation, migration, and gene expression. Methods and Results-VSMCs were infected with recombinant adenovirus containing dominant-negative mutants of ERK, p38, and JNK (Ad-DN-ERK, Ad-DN-p38, and Ad-DN-JNK, respectively) to specifically inhibit the respective MAP kinases and then stimulated with platelet-derived growth factor (PDGF)-BB. Ad-DN-ERK attenuated PDGF-BB-induced VSMC proliferation more potently than Ad-DN-p38 or Ad-DN-JNK, indicating the dominant role of ERK in VSMC proliferation. Ad-DN-ERK, Ad-DN-p38, and Ad-DN-JNK similarly inhibited PDGF-induced VSMC migration. Ad-DN-ERK and Ad-DN-JNK suppressed PDGF-BB-induced downregulation of cyclin-dependent kinase inhibitor p27 Kip1 , whereas Ad-DN-p38 decreased PDGF-BB-induced upregulation of p21 Cip1 . Ad-DN-ERK inhibited PDGF-BB-induced plasminogen activator inhibitor type-1 (PAI-1), monocyte chemoattractant protein-1, and transforming growth factor-␤ 1 expressions, Ad-DN-p38 blocked monocyte chemoattractant protein-1 and transforming growth factor-␤ 1 expression but not PAI-1, whereas Ad-DN-JNK suppressed only PAI-1 expression. Moreover, in vivo gene transfer of Ad-DN-p38 to rat carotid artery caused the inhibition of intimal hyperplasia by balloon injury, indicating the involvement of p38 in vascular remodeling in vivo. Key Words: platelet-derived growth factor Ⅲ gene transfer Ⅲ vascular smooth muscle cell Ⅲ proliferation Ⅲ gene expression P latelet-derived growth factor-BB (PDGF-BB) is one of the most potent mitogens and chemoattractants for vascular smooth muscle cells (SMCs) and plays the central role in the onset and development of various vascular disorders. [1][2][3][4][5][6] As reviewed, 7,8 PDGF-BB, through interaction with PDGF, activates multiple signaling pathways in vascular SMCs, including SHP-2, Src, PLC-␥, Ras, protein kinase A, phosphatidylinositol 3-kinase (PI3-kinase), and mitogen-activated protein (MAP) kinases, which are supposed to play some role in PDGF-induced cellular responses. Ras, 9 Src, 10 and c-Jun 11 contribute to PDGFinduced vascular SMC proliferation. On the other hand, PI 3-kinase is known to participate in PDGF-induced vascular SMC migration. 12 However, the molecular mechanism of vascular SMC proliferation and migration by PDGF-BB remains to be fully understood. PDGF-BB not only stimulates proliferation and migration in vascular SMCs but also induces various genes. Interestingly, previous reports indicate that PDGF-BB induces plasminogen activator inhibitor type-1 (PAI-1), monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-␤ 1 (TGF-␤ 1 ) in vascular SMCs. [13][14][15] Increased PAI-1 that leads to inhibition of plasminogen activation impairs fibrinolysis and thereby promotes thrombosis. 16 MCP-1 is the major chemotactic factor involved in the migration of monocytes into...

Oxidative stress, which is found in pancreatic ␤-cells in the diabetic state, suppresses insulin gene transcription and secretion, but the signaling pathways involved in the ␤-cell dysfunction induced by oxidative stress remain unknown. In this study, subjecting rat islets to oxidative stress activates JNK, p38 MAPK, and protein kinase C, preceding the decrease of insulin gene expression. Adenovirus-mediated overexpression of dominantnegative type (DN) JNK, but not the p38 MAPK inhibitor SB203580 nor the protein kinase C inhibitor GF109203X, protected insulin gene expression and secretion from oxidative stress. Moreover, wild type JNK overexpression suppressed both insulin gene expression and secretion. These results were correlated with changes in the binding of the important transcription factor PDX-1 to the insulin promoter; adenoviral overexpression of DN-JNK preserved PDX-1 DNA binding activity in the face of oxidative stress, whereas wild type JNK overexpression decreased PDX-1 DNA binding activity. Furthermore, to examine whether suppression of the JNK pathway can protect ␤-cells from the toxic effects of hyperglycemia, rat islets were infected with DN-JNK expressing adenovirus or control adenovirus and transplanted under renal capsules of streptozotocin-induced diabetic nude mice. In mice receiving DN-JNK overexpressing islets, insulin gene expression in islet grafts was preserved, and hyperglycemia was ameliorated compared with control mice. In conclusion, activation of JNK is involved in the reduction of insulin gene expression by oxidative stress, and suppression of the JNK pathway protects ␤-cells from oxidative stress.

Abstract-Multiple lines of evidence establish that angiotensin II (Ang II) induces not only hypertension but also directly contributes to cardiac diseases. Apoptosis signal-regulating kinase 1 (ASK1), one of mitogen-activated protein kinase kinase kinases, plays a key role in stress-induced cellular responses. However, nothing is known about the role of ASK1 in cardiac hypertrophy and remodeling in vivo. In this study, by using mice deficient in ASK1 (ASK1 Ϫ/Ϫ mice), we investigated the role of ASK1 in cardiac hypertrophy and remodeling induced by Ang II. Left ventricular (LV) ASK1 was activated by Ang II infusion in wild-type mice, which was mediated by angiotensin II type 1 receptor and superoxide. Although Ang II-induced hypertensive effect was comparable to wild-type and ASK1Ϫ/Ϫ mice, LV ASK1 activation by Ang II was not detectable in ASK1 Ϫ/Ϫ mice, and p38 and c-Jun N-terminal kinase (JNK) activation was lesser in ASK Ϫ/Ϫ mice than in wild-type mice. Elevation of blood pressure by continuous Ang II infusion was comparable between ASK1Ϫ/Ϫ and wild-type mice. However, Ang II-induced cardiac hypertrophy and remodeling, including cardiomyocyte hypertrophy, cardiac hypertrophy-related mRNA upregulation, cardiomyocyte apoptosis, interstitial fibrosis, coronary arterial remodeling, and collagen gene upregulation, was significantly attenuated in ASK1 Ϫ/Ϫ mice compared with wild-type mice. These results provided the first in vivo evidence that ASK1 is the critical signaling molecule for Ang II-induced cardiac hypertrophy and remodeling. Thus, ASK1 is proposed to be a potential therapeutic target for cardiac diseases.