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Background-Rho and its effector Rho-kinase/ROCK mediate cytoskeletal reorganization as well as smooth muscle contraction. Recent studies indicate that Rho and ROCK are critically involved in vascular remodeling. Here, we tested the hypothesis that Rho/ROCK are critically involved in angiotensin II (Ang II)-induced migration of vascular smooth muscle cells (VSMCs) by mediating a specific signal cross-talk. Methods and Results-Immunoblotting demonstrated that Ang II stimulated phosphorylation of a ROCK substrate, regulatory myosin phosphatase targeting subunit (MYPT)-1. Phosphorylation of MYPT-1 as well as migration of VSMCs induced by Ang II was inhibited by dominant-negative Rho (dnRho) or ROCK inhibitor, Y27632. Ang II-induced c-Jun NH 2 -terminal kinase (JNK) activation, but extracellular signal-regulated kinase (ERK) activation was not mediated through Rho/ROCK. Thus, infection of adenovirus encoding dnJNK inhibited VSMC migration by Ang II. We have further demonstrated that the Rho/ROCK activation by Ang II requires protein kinase C-␦ (PKC␦) and proline-rich tyrosine kinase 2 (PYK2) activation, but not epidermal growth factor receptor transactivation. Also, VSMCs express PDZ-Rho guanine nucleotide exchange factor (GEF) and Ang II stimulated PYK2 association with tyrosine phosphorylated PDZ-RhoGEF. A ngiotensin II (Ang II) has been implicated in various cardiovascular diseases such as hypertension, atherosclerosis, and restenosis after angioplasty. 1 Therefore, there has been considerable interest in defining the functional significance of signaling pathways of the Ang II type 1 receptor (AT 1 ), which is dominantly expressed in vascular smooth muscle cells (VSMCs). 1-3 Through this receptor, Ang II stimulates hypertrophy and hyperplasia of VSMCs. 2 The AT 1 receptor primarily couples to G q leading to elevation of intracellular Ca 2ϩ and activation of protein kinase C (PKC). 2 In addition, tyrosine kinase activation by Ang II is linked to downstream mitogenactivated protein kinase (MAPK) activation, thereby mediating the growth promoting response in VSMCs. 2,4,5 In this regard, several key tyrosine kinases have been identified that may contribute to the growth-promoting effects of the AT 1 receptor. These kinases include epidermal growth factor receptor (EGFR) and proline-rich tyrosine kinse 2 (PYK2). 4,5 In addition to its growth responses, VSMC migration by Ang II is strongly implicated in various cardiovascular diseases, 6 whereas the detailed signaling mechanisms by which the AT 1 receptor mediates migration are insufficiently characterized. At least, a MAPK, ERK appears to be required for Ang II-induced migration of VSMCs. 7 Recently, Zahn et al showed that 3 major MAPKs, ERK, p38MAPK, and c-Jun NH 2 -terminal kinase (JNK), are all required for VSMC migration induced by platelet-derived growth factor (PDGF), 8 suggesting that these MAPKs coordinately mediate VSMC migration. A small G protein, Rho, and its effector Rho-kinase/ ROCK, are involved in many aspects of cell motility, from smooth muscle...

Accumulating evidence strongly implicates angiotensin II (AngII) intracellular signaling in mediating cardiovascular diseases such as hypertension, atherosclerosis and restenosis after vascular injury. In vascular smooth muscle cells (VSMCs), through its G-protein-coupled AngII Type 1 receptor (AT(1)), AngII activates various intracellular protein kinases, such as receptor or non-receptor tyrosine kinases, which includes epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), c-Src, PYK2, FAK, JAK2. In addition, AngII activates serine/threonine kinases such as mitogen-activated protein kinase (MAPK) family, p70 S6 kinase, Akt/protein kinase B and various protein kinase C isoforms. In VSMCs, AngII also induces the generation of intracellular reactive oxygen species (ROS), which play critical roles in activation and modulation of above signal transduction. Less is known about endothelial cell (EC) AngII signaling than VSMCs, however, recent studies suggest that endothelial AngII signaling negatively regulates the nitric oxide (NO) signaling pathway and thereby induces endothelial dysfunction. Moreover, in both VSMCs and ECs, AngII signaling cross-talk with insulin signaling might be involved in insulin resistance, an important risk factor in the development of cardiovascular diseases. In fact, clinical and pharmacological studies showed that AngII infusion induces insulin resistance and AngII converting enzyme inhibitors and AT(1) receptor blockers improve insulin sensitivity. In this review, we focus on the recent findings that suggest the existence of novel signaling mechanisms whereby AngII mediates processes, such as activation of receptor or non-receptor tyrosine kinases and ROS, as well as cross-talk between insulin and NO signal transduction in VSMCs and ECs.

To investigate the chronologic change of mother-to-child transmission of human T lymphotropic virus type I (HTLV-I) in Okinawa, Japan, the presence of antibody to HTLV-I was tested in 4,187 healthy residents between, 4,528 nursery school children, and 3,837 pregnant women between 1968 and 2000. The chronologic change of the feeding method and the length of the breast-feeding period among 1,117 healthy mothers from 1937 to 1995 were also obtained by interview. Age-adjusted prevalence of HTLV-I among healthy residents decreased from 9.1% in 1968-1970 to 7.8% in 1981-1984 and to 6.3% in 1996-1998. The crude prevalence of antibody to HTLV-I among healthy residents less than 20 years old decreased significantly from 4.6% in 1968-1970 to 0.1% in 1996-1998 (P < 0.0001). The prevalence of antibody to HTLV-I among nursery school children decreased significantly over the study period, from a high of 1.8% in 1984 to a low of 0.2% in 1998 (P = 0.03). The prevalence among pregnant women decreased significantly from 5.6% in 1989-1992 to 3.7% in 1997-2000 (P = 0.0275). Prior to 1967, all healthy mothers breast-fed their children. After 1968, the use of bottled and mixed milk (breast milk and bottled milk) increased, with bottled milk becoming predominant after 1990 (89%). The percentage of healthy mothers breast-feeding for more than one year significantly decreased from 68.3% in 1937-1947 to 0.4% in 1990-1995 (P < 0.0001). Infection with HTLV-I in Okinawa has decreased mainly due to a reduction in the number of mothers breast-feeding and a shortening of the breast-feeding period. However, because the mother-to-child transmission rate among non-breast-feeders decreased from 12.8% in 1986-1991 to 3.2% in 1995-1999, there may be other factors involved in the decrease in mother-to-child transmission.