Serotonin-induced growth of pulmonary artery smooth muscle requires activation of phosphatidylinositol 3-kinase/serine-threonine protein kinase B/mammalian target of rapamycin/p70 ribosomal S6 kinase 1

We have previously found that both mitogen-activated protein kinase (MAPK)- and Rho kinase (ROCK)-related signaling pathways are necessary for the induction of pulmonary artery smooth muscle cell (SMC) proliferation by serotonin (5-hydroxytryptamine [5-HT]). In the present study, we investigated the possible additional participation of a phosphatidylinositol 3-kinase (PI3K)/serine-threonine protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/p70 ribosomal S6 kinase (S6K1) pathway in this growth response. We found transient activation of Akt (Ser473) and more prolonged activation of S6K1 by 5-HT. Inhibition of PI3K with Wortmannin and LY294002 completely blocked these activations, but not that of MAPK or the ROCK substrate myosin phosphatase targeting subunit. Similarly, inhibition of MAPK and ROCK failed to block the Akt activation. Inhibition of Akt with NL-71-101 and downregulation of Akt expression with Akt small interfering RNA blocked 5-HT-induced S6K1 phosphorylation. Wortmannin, LY294002, and NL-71-101 dose-dependently inhibited 5-HT-induced SMC proliferation. 5-HT stimulated mTOR phosphorylation and the mTOR inhibitor, rapamycin, blocked activations of S6K1 and S6 ribosomal protein, and inhibited 5-HT-induced SMC proliferation. Akt phosphorylation and cell proliferation were also blocked by the antioxidants, N-acetyl-l-cysteine, Ginko biloba 501, and tiron, the reduced nicotinamide adenine dinucleotide phosphate oxidase inhibitor, diphenyleneiodonium, and the 5-HT2 receptor antagonists ketanserin and mianserin, but not by the 5-HT serotonin transporter or 5-HT 1B/1D receptor antagonists. We conclude from these studies that a parallel PI3K- and reactive oxygen species-dependent Akt/mTOR/S6K1 pathway participates independently from MAPK and Rho/ROCK in the mitogenic effect of 5-HT on pulmonary artery SMCs. From these and other studies, we postulate that independent signaling pathways leading to 5-HT-induced SMC proliferation are initiated through multiple 5-HT receptors and serotonin transporter at the cell surface.     

PI3K/Akt and ERK1/2 signalling pathways are involved in endometrial cell migration induced by 17beta-estradiol and growth factors

Cell motility and invasion are crucial events for endometrial cells, not only for the establishment of pathological states but also during the physiological tissue remodelling that occurs during the menstrual cycle and embryo implantation. We have characterized these phenomena in endometrial stromal cells evaluating cell migration-specific stimuli and the biochemical pathways involved. Ability of endometrial cells to migrate on collagen type IV substrate was evaluated by means of chemotaxis experiments. Modulation of this phenomenon by different growth factors and steroid hormones and their ability to activate extracellular signal-regulated protein kinase (ERK) and phosphatidylinositol 3 kinase (PI3K)/Akt signalling in this context were examined. Platelet-derived growth factor (PDGF)-BB, epidermal growth factor and fibroblast growth factor-2 as chemoattractant agents stimulated basal migration of endometrial stromal cells through the rapid activation of both ERK1/2 and PI3K/Akt signalling pathways. Experiments using wortmannin and PD98059, specific inhibitors of the PI3K/Akt and ERK1/2 activity, respectively, showed that the activation of both pathways is required for growth-factor-induced cell motility responses. Similarly, 17beta-estradiol (10(-6)-10(-8) M) could enhance both constitutive and PDGF-induced migration of the cells and their rapid treatment with the hormone significantly increased phosphorylation of ERK1/2 and Akt. Conversely, progesterone did not interfere with the basal migration but inhibits the PDGF-induced motility of this cell type. Rapid activation of intracellular signalling cascades ERK1/2 and PI3K/Akt by growth factors and estrogens is involved in the migration of normal endometrial stromal cells.     

Differential effect of FGF and PDGF on cell proliferation and migration in osteoblastic cells

It has been known that growth factors such as fibroblast growth factor (FGF) and platelet-derived growth factor (PDGF) can promote proliferation and migration in a variety of cell types including osteoblastic cells. However, the mechanism underlying their action has not been clearly defined. The present study was undertaken to examine the effect of FGF and PDGF on cell proliferation and migration and to determine the role of extracellular signal-regulated kinase (ERK) and Akt in action of FGF and PDGF in osteoblastic cells. FGF enhanced proliferation in a dose- and time-dependent manner, whereas it did not affect cell migration. FGF induced a transient activation of ERK, but not Akt, which was inhibited by an inhibitor of MEK, the upstream kinase of ERK, but not by inhibitors of PI3K/Akt (LY294002), epidermal growth factor receptor (EGFR, AG1478), and Src (PP2). FGF-induced proliferation was inhibited by inhibitors of MEK/ERK and Src pathways. Exposure of cells to FGF stimulated transition of cell cycle from the G1 phase to S phase and increased phosphorylation of Rb. FGF-induced phosphorylation of Rb was attenuated by inhibitors of MEK/ERK and Src pathways. Cell migration studies indicated that PDGF stimulated migration, but it had no effect on cell proliferation. PDGF induced activation of ERK and Akt. The ERK activatin was inhibited by the Src inhibitor and the Akt activation was inhibited by inhibitors of EGFR and Src. PDGF-induced migration was inhibited by inhibitors of MEK/ERK, PI3K/Akt, EGFR and Src pathways. Taken together, these findings suggest that the MEK/ERK and Src pathways play an important role in the FGF-induced proliferation and signaling pathways involving MEK/ERK, EGFR, Src and PI3K/Akt mediate the PDGF-induced migration. These data are of importance in understanding the roles of these growth factors in osteoblastic cell proliferation and migration.     

Retinoic acids acting through retinoid receptors protect hippocampal neurons from oxygen-glucose deprivation-mediated cell death by inhibition of c-jun-N-terminal kinase and p38 mitogen-activated protein kinase

Retinoic acids (RAs), including all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9-cis RA), play fundamental roles in a variety of physiological events in vertebrates, through their specific nuclear receptors: retinoic acid receptor (RAR) and retinoid X receptor (RXR). Despite the physiological importance of RA, their functional significance under pathological conditions is not well understood. We examined the effect of ATRA on oxygen/glucose-deprivation/reperfusion (OGD/Rep)-induced neuronal damage in cultured rat hippocampal slices, and found that ATRA significantly reduced neuronal death. The cytoprotective effect of ATRA was observed not only in cornu ammonis (CA) 1 but also in CA2 and dentate gyrus (DG), and was attenuated by selective antagonists for RAR or RXR. By contrast, in the CA3 region, no protective effects of ATRA were observed. The OGD/Rep also increased phosphorylated forms of c-jun-N-terminal kinase (P-JNK) and p38 (P-p38) in hippocampus, and specific inhibitors for these kinases protected neurons. ATRA prevented the increases in P-JNK and P-p38 after OGD/Rep, as well as the decrease in NeuN and its shrinkage, all of which were inhibited by antagonists for RAR or RXR. These findings suggest that the ATRA signaling via retinoid receptors results in the inhibition of JNK and p38 activation, leading to the protection of neurons against OGD/Rep-induced damage in the rat hippocampus.     

Convergence of physical and chemical signaling in the modulation of vascular smooth muscle cell cycle and proliferation by fibrillar collagen-regulated P66Shc

Arterial smooth muscle cell (SMC) phenotype and proliferation is regulated by their surrounding collagens, which transform from fibrillar to monomeric type in atherogenesis, and platelet-derived growth factor (PDGF)-BB/interleukin (IL)-1β. This study aims at elucidating the mechanisms by which physical (monomeric vs. fibrillar collagens) and chemical (PDGF-BB/IL-1βvs. vehicle controls) stimuli modulate SMC cycle and proliferation. SMCs were cultured on monomeric vs. fibrillar type I collagens. In parallel experiments, SMCs on fibrillar collagen were co-stimulated with PDGF-BB/IL-1β. These physical and chemical factors induced common SMC cycle signaling events, including up-regulations of cyclin-dependent kinase-4/6 and cyclins A/D1, phosphorylation of retinoblastoma (Rb) and its dissociations with E2F2/3. The physical and chemical inductions of SMC cycle signaling and progression were oppositely regulated by phosphatidylinositol 3-kinase (PI3K)-mediated Akt and p38 mitogen-activated protein kinase (MAPK). Fibrillar collagen degraded p66Shc, whose Ser36-phosphorylation plays important roles in the modulation of SMC cycle. Monomeric collagen and PDGF-BB/IL-1β co-stimulation induced p66Shc expression and Ser36-phosphorylation through β(1) integrin and PDGF receptor-β, respectively. In conclusion, our results demonstrate that fibrillar collagen-regulated p66Shc converges the physical and chemical stimuli to modulate SMC cycle and proliferation through PI3K-mediated Akt and p38 MAPK and their opposite regulation in downstream common cell cycle signaling cascades.     

Insulin-like growth factor-1 induces phosphorylation of PI3K-Akt/PKB to potentiate proliferation of smooth muscle cells in human saphenous vein

Coronary revascularization by coronary artery bypass grafting (CABG) is recommended in patients with recurrent myocardial ischemia. However, the long-term results of CABG using saphenous vein (SV) graft, compared to internal mammary artery (IMA) graft, have not been satisfactory. The SV graft failure is due to the development of intimal hyperplasia, a process characterized by abnormal migration and proliferation of smooth muscle cells (SMCs) in the intimal layer of the vein graft. Insulin growth factor 1 (IGF-1) is a major mitogenic growth factor released at the site of the shear stress-induced graft injury. This study, for the first time, compares the extent of IGF-1-PI3K-Akt activation in isolated human bypass graft conduits. Human SV and IMA vessels were collected and SMCs isolated and cultured. In cultured SMCs, effect of IGF-1 was examined on total and phosphorylated PI3K, Akt and IGF-1R by Western blot analysis. Cell proliferation was measured using BrdU ELISA. There was no significant difference in the basal expression of phosphorylated PI3K, Akt and IGF-1R in SV and IMA SMCs from human bypass conduits. However, we observed an upregulation of IGF-1 receptors in the SV SMCs in response to IGF-1 stimulation with no effect in IMA SMCs. Furthermore, the immunoblotting and cellular activation of signaling ELISA (CASE) assay demonstrated a significantly higher activity of both PI3K and Akt in IGF-1-stimulated SV SMCs than IMA. This was inhibited by an IGF-1R blocking antibody. IGF-1 induced proliferation in both SV and IMA SMCs was inhibited by a PI3K inhibitor, wortmannin. These data demonstrate differential activity of IGF-1-induced PI3K-Akt activation, which was quantitatively and temporally greater in SV SMCs than in the IMA. This, at least in part, could explain the greater propensity of the SV conduits than the IMA to undergo intimal hyperplasia following CABG.     

Antibody ligation of human leukocyte antigen class I molecules stimulates migration and proliferation of smooth muscle cells in a focal adhesion kinase-dependent manner

Chronic rejection manifests as transplant vasculopathy, which is characterized by intimal thickening of the vessels of the allograft. Intimal thickening is thought to result from the migration and proliferation of vascular smooth muscle cells (SMC) in the vessel media, followed by deposition of extracellular matrix proteins. The development of post-transplantation anti-human leukocyte antigen (HLA) antibodies (Ab) is strongly correlated with the development of transplant vasculopathy and graft loss. Here we demonstrate that cross-linking of HLA class I molecules on the surface of human SMC with anti-HLA class I Ab induced cell proliferation and migration. Class I ligation also increased phosphorylation of focal adhesion kinase (FAK), Akt, and ERK1/2 in SMC. Knockdown of FAK by siRNA attenuated class I-induced phosphorylation of Akt and ERK1/2, as well as cell proliferation and migration. These results indicate that ligation of HLA class I molecules induces SMC migration and proliferation in a FAK-dependent manner, which may be important in promoting transplant vasculopathy.     

Inhibition of airway smooth muscle adhesion and migration by the disintegrin domain of ADAM-15

Disintegrin and metalloprotease proteins (ADAMs) are membrane-anchored glycoproteins involved in cell adhesion, cell fusion, protein ecto-domain shedding, and intracellular signaling. We examined whether the disintegrin domain of ADAM-15 (named ddADAM-15) containing an Asp-Gly-Asp (RGD) integrin-binding motif could interfere with airway smooth muscle cell (ASMC) adhesion and migration. Recombinant ddADAM-15 adhered to human ASMCs with saturation kinetics, and was beta(1)-integrin dependent. ddADAM-15 inhibited the binding of fibrinogen but not of fibronectin to ASMCs. ddADAM-15 also inhibited platelet-derived growth factor (PDGF)-induced ASMC migration, and this was reversed by an anti-beta(1)-integrin antibody. PDGF induced the activation of phosphoinositol-3-kinase (PI3K) and p38 mitogen-activated protein kinase (MAPK), and selective inhibitors of these kinases inhibited PDGF-induced ASMC migration. ddADAM-15 did not inhibit PDGF-induced activation of PI3K or p38, thereby excluding these kinase pathways as a mechanism by which ddADAM-15 inhibits ASMC migration. ADAM-15 mRNA and protein were expressed under basal conditions, and both gene and protein expression were inhibited by PDGF. In summary, ddADAM-15 inhibits ASMC adhesion and migration through the beta(1)-integrin, without modulating signaling pathways involved in ASMC migratory responses.     

Akt、ERK1/2活化在脑源性神经营养因子促血管新生中的作用

目的： 探讨脑源性神经营养因子(BDNF) 促进血管新生的作用及其参与的信号通路,为抗肿瘤血管生成的研究提供新的实验依据。 方法: 以人脐静脉内皮细胞为对象,采用Western 印迹方法检测细胞内磷酸化Akt、ERK1/2蛋白质的表达； 采用Transwell小室迁移实验、管腔形成实验评价体外内皮细胞血管新生的能力，MTT法检测内皮细胞增殖 活性，FITC-Annexin-Ⅴ/PI双染流式细胞术分析细胞凋亡。 结果: BDNF以时间依赖性方式激活PI3K/Akt 和MEK1/ERK信号通路。分别应用PI3K激酶抑制剂Ly294002、 MEK1激酶抑制剂PD98059可以明显阻断BDNF对PI3K/Akt、MEK1/ERK信号通路的激活。100 μg/L 的BDNF体 外促内皮细胞血管新生能力与 25 μg/L 血管内皮生长因子（VEGF）相当， 其中BDNF诱导的细胞迁移分 别被Ly294002和PD98059阻断，其抑制率分别约为74%和36%；同样，Ly294002、PD98059可部分阻断BDNF诱 导的小管形成效应，其阻断率分别约57%和37%；而BDNF的促增殖效应仅被PD98059拮抗，抑制凋亡效应仅受Ly294002影响。 结论: BDNF在体外有促血管新生的作用。PI3K/Akt 和MEK1/ERK信号通路以不同机制共同调节这一过程,其中PI3K/Akt信号通路起着更为重要的调节作用。     

Phophatidylinositol-3 kinase/mammalian target of rapamycin/p70S6K regulates contractile protein accumulation in airway myocyte differentiation

Increased airway smooth muscle in airway remodeling results from myocyte proliferation and hypertrophy. Skeletal and vascular smooth muscle hypertrophy is induced by phosphatidylinositide-3 kinase (PI(3) kinase) via mammalian target of rapamycin (mTOR) and p70S6 kinase (p70S6K). We tested the hypothesis that this pathway regulates contractile protein accumulation in cultured canine airway myocytes acquiring an elongated contractile phenotype in serum-free culture. In vitro assays revealed a sustained activation of PI(3) kinase and p70S6K during serum deprivation up to 12 d, with concomitant accumulation of SM22 and smooth muscle myosin heavy chain (smMHC) proteins. Immunocytochemistry revealed that activation of PI3K/mTOR/p70S6K occurred almost exclusively in myocytes that acquire the contractile phenotype. Inhibition of PI(3) kinase or mTOR with LY294002 or rapamycin blocked p70S6K activation, prevented formation of large elongated contractile phenotype myocytes, and blocked accumulation of SM22 and smMHC. Inhibition of MEK had no effect. Steady-state mRNA abundance for SM22 and smMHC was unaffected by blocking p70S6K activation. These studies provide primary evidence that PI(3) kinase and mTOR activate p70S6K in airway myocytes leading to the accumulation of contractile apparatus proteins, differentiation, and growth of large, elongated contractile phenotype airway smooth muscle cells.     

Role of licochalcone A in VEGF-induced proliferation of human airway smooth muscle cells: implications for asthma

Asthma is a chronic respiratory disease characterized by reversible airway obstruction with persistent airway inflammation and airway remodeling, which is associated with increased airway smooth muscle (ASM) mass. Licochalcone A is the predominant characteristic chalcone in licorice root. We found that licochalcone A inhibited vascular endothelial growth factor (VEGF)-induced ASM cell proliferation and induced cell cycle arrest. Additionally, VEGF-induced ASM cell proliferation was suppressed via inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activity, but not that of Akt. Furthermore, licochalcone A treatment inhibited VEGF-induced activation of VEGF receptor 2 (VEGFR2) and ERK and blocked the downregulation of caveolin-1 in a concentration-dependent manner. Collectively, our findings suggested that licochalcone A inhibited VEGF-induced ASM cell proliferation by suppressing VEGFR2 and ERK1/2 activation and downregulating caveolin-1. Further studies of these mechanisms are needed to facilitate the development of treatments for smooth muscle hyperplasia-associated diseases of the airway, such as asthma.     

Integrin-linked kinase in the vascular smooth muscle cell response to injury

Integrin-mediated interactions between smooth muscle cells (SMCs) and the extracellular matrix regulate cell migration and proliferation during neointimal hyperplasia. Integrin-linked kinase (ILK) is a serine-threonine kinase and scaffolding molecule that acts downstream of integrin receptors to modulate cell adhesion; therefore, we examined ILK function in SMCs during wound repair. Silencing of ILK expression with siRNA in vitro decreased cell adhesion to fibronectin and accelerated both cell proliferation and wound closure in the cell monolayer; it also resulted in the rearrangement of focal adhesions and diminished central actin stress fibers. Akt and GSK3beta are ILK substrates that are important in cell motility; however, ILK siRNA silencing did not attenuate injury-induced increases in Akt and GSK3beta phosphorylation. Following balloon catheter injury of the rat carotid artery in vivo, a dramatic decrease in ILK levels coincided with both the proliferation and migration of SMCs, which leads to the formation of a thickened neointima. Immunostaining revealed decreased ILK levels in the media and deep layers of the neointima, but increased ILK levels in the subluminal layers of the intima. Taken together, these results suggest that ILK functions to maintain SMC quiescence in the normal artery. A decrease in ILK levels after injury may permit SMC migration, proliferation, and neointimal thickening, and its re-expression at the luminal surface may attenuate this process during later stages of the injury response.     

叶酸通过下调ERK1/2信号通路抑制血管平滑肌细胞增殖和迁移

目的:探讨叶酸(folic acid,FA)对血管平滑肌细胞(VSMCs)增殖和迁移的影响及其机制。方法:取SD大鼠的主动脉,采用组织贴块法培养VSMCs,随机分组进行实验。采用CCK-8和Ed U法检测叶酸对VSMCs活力和增殖能力的影响。采用划痕实验和Transwell法检测叶酸对VSMCs迁移和侵袭的影响。采用Western blot法检测细胞增殖核抗原(PCNA)蛋白表达以及血小板源性生长因子受体(PDGFR)和细胞外信号调节激酶1/2(ERK1/2)蛋白的磷酸化水平。结果:叶酸抑制血小板源性生长因子(PDGF)诱导的VSMCs的活力,并呈浓度依赖性(P0.05)。叶酸抑制PDGF诱导的VSMCs的迁移,并呈浓度依赖性(P0.05)。叶酸降低PCNA表达和PDGFR磷酸化水平,并抑制PDGF激活的ERK1/2信号通路。结论:叶酸降低PDGF诱导的VSMCs PCNA和p-PDGFR蛋白水平,下调ERK1/2信号通路,从而抑制VSMCs的增殖和迁移。     

Aspirin Inhibits LPS-Induced Expression of PI3K/Akt,ERK, NF-κB,CX3CL1, and MMPs in Human Bronchial Epithelial Cells

This study focused on the effects of aspirin on lipopolysaccharide (LPS)-induced expression of phosphoinositide 3 kinase (PI3K)/protein kinase B (Akt), extracellular signal-regulated protein kinase (ERK), nuclear factor-κB (NF-κB), CX3CL1, and MMPs in human bronchial epithelial cells. Human bronchial epithelial cells were seeded in six-well plates. After 24 h, the cells were classified into six groups: control blank (CK) group; LPS group; PD98059 (ERK inhibitor) (PD) group, treated with LPS + ERK inhibitor; LY294002(PI3K/Akt inhibitor) (LY) group, treated with LPS + PI3K/Akt inhibitor; Aspirin (Asp) group, treated with LPS + aspirin; and Pyrrolidinedithiocarbamic acid (PDTC) group, treated with LPS + NF-κB inhibitor. After 4-h treatment, the cells were harvested. Western blot analysis was performed to detect the expression of PI3K/Akt, ERK, NF-κB, and CX3CL1. Real-time quantitative PCR (RT-qPCR) was used to determine the gene expression of MMP-7, MMP-9, and MMP-12. Compared to the CK group, expression of PI3K/Akt, ERK, NF-κB, and CX3CL1 was significantly increased in the LPS group (P?<?0.05). When compared to the LPS group, expression of PI3K/Akt, ERK, NF-κB, and CX3CL1 was significantly decreased in the PD group, PDTC group, and Asp group (P?<?0.05). In addition, expression of NF-κB in the LY group was significantly reduced by comparison with the LPS group (P?<?0.05). RT-qPCR: When compared to the LPS group, expression of MMP-7 and MMP-12 was significantly decreased in Asp group (P?<?0.05). Expression of MMP-12 was significantly reduced in LY group (P?<?0.05). LPS-ERK, NF-κB-PI3K/Akt, and CX3CL1 signal pathways exist in human bronchial epithelial cells. The PI3K/Akt inhibitor repressed expression of MMP-12. Aspirin inhibited LPS-induced expression of PI3K, Akt, ERK, NF-κB, CX3CL1, MMP-7, and MMP-12 in human bronchial epithelial cells.     

Mitogenic signaling pathways in airway smooth muscle

Increased airway smooth muscle mass has been demonstrated in patients with asthma, bronchopulmonary dysplasia and most recently, cystic fibrosis. These observations emphasize the need for further knowledge of the events involved in airway smooth muscle mitogenesis and hypertrophy. Workers in the field have developed cell culture systems involving tracheal and bronchial myocytes from different species. An emergent body of literature indicates that mutual signal transduction pathways control airway smooth muscle cell cycle entry across species lines. This article reviews what is known about mitogen-activated signal transduction in airway myocytes. The extracellular signal regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI 3-kinase) pathways appear to be key positive regulators of airway smooth muscle mitogenesis; recent studies have also demonstrated specific roles for reactive oxygen and the JAK/STAT pathway. It is also possible that growth factor stimulation of airway smooth muscle concurrently elicits signaling through negative regulatory intermediates such as p38 mitogen-activated protein (MAP) kinase and protein kinase C (PKC) delta, conceivably as a defense against extreme growth.     

Bis(1-oxy-2-pyridinethiolato)oxovanadium(IV) enhances neurogenesis via phosphatidylinositol 3-kinase/Akt and extracellular signal regulated kinase activation in the hippocampal subgranular zone after mouse focal cerebral ischemia

Although neurogenesis in the hippocampus is critical for improvement of depressive behaviors and cognitive functions in neurodegeneration disorders, there is no therapeutic agent available to promote neurogenesis in adult brain following brain ischemic injury. Here we found that i.p. administration of bis(1-oxy-2-pyridinethiolato)oxovanadium(IV) [VO(OPT)], which stimulates phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal regulated kinase (ERK) pathways, markedly enhanced brain ischemia-induced neurogenesis in the subgranular zone (SGZ) of the mouse hippocampus. VO(OPT) treatment enhanced not only the number of proliferating cells but also migration of neuroblasts. VO(OPT)-induced neurogenesis was associated with Akt and ERK activation in neural precursors in the SGZ. Likewise, VO(OPT)-induced neurogenesis was blocked by both PI3K/Akt and mitogen-activated protein kinase/extracellular signal regulated kinase kinase (MEK)/ERK inhibitors. VO(OPT) treatment rescued decreased phosphorylation of glycogen synthesis kinase 3beta (GSK-3beta) at Ser-9. Finally, amelioration of cognitive dysfunction seen following brain ischemia was positively correlated with VO(OPT)-induced neurogenesis. Taken together, VO(OPT) is a potential therapeutic agent that enhances ischemia-induced neurogenesis through PI3K/Akt and ERK activation, thereby improving memory and cognitive deficits following brain ischemia.     

Effects of extracellular matrix on phenotype modulation and MAPK transduction of rat aortic smooth muscle cells in vitro

The transition of arterial smooth muscle cells (SMCs) from a contractile to a synthetic phenotype may play an essential role in the formation of atherosclerotic and restenotic lesions. This process includes a prominent structural reorganization and allows cells to acquire the ability to migrate, proliferate, and secrete extracellular matrix components. According to Western blotting analysis and immunohistochemical and morphological observations, laminin not only retains SMCs in a contractile state but also possibly stimulates cells to transform a synthetic to a contractile phenotype at an early stage, mediated by P38 MAPK signal transduction. However, fibronectin promotes SMCs to transform from a contractile to a synthetic phenotype, mediated by the ERK MAPK signal pathway. The localization of smooth muscle alpha -actin, myosin heavy chain isoform SM2, and vimentin in explant-isolated rat SMCs was affected by a substrate of fibronectin and laminin and also by ERK MAP kinase inhibitor (PD098059) and P38 MAPK inhibitor (SB203580). Furthermore, vimentin may play a much more important role in differentiation than desmin in phenotype modulation in rat aortic smooth muscle cells.