酸性成纤维细胞生长因子促进大鼠肠缺血-再灌注损伤的修复

背景：细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2在肠缺血-再灌注损伤修复中的作用尚无研究报道。 目的：观察大鼠肠缺血-再灌注损伤后外源性酸性成纤维细胞生长因子对细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2表达的影响,探讨细胞外调节蛋白激酶和酸性成纤维细胞生长因子受体2与酸性成纤维细胞生长因子促进创伤修复的关系。 方法：以大鼠肠系膜上动脉夹闭45 min造成肠缺血-再灌注损伤模型,于再灌注即刻应用酸性成纤维细胞生长因子行干预。分别于再灌注2,6,12,24 h取大鼠小肠组织标本,利用免疫组化和RT-PCR检测酸性成纤维细胞生长因子受体的表达及免疫组化检测细胞外调节蛋白激酶表达的规律。 结果与结论：在正常大鼠,酸性成纤维细胞生长因子受体2主要分布在小肠绒毛上皮细胞的肠腔侧、侧壁和小肠隐窝朝向隐窝腔的一侧细胞膜上。缺血-再灌注初期,酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达未发生明显变化,但随着再灌注时间的延长表达水平逐渐提高,并于再灌注后6-12 h达高峰。经酸性成纤维细胞生长因子治疗后,大鼠小肠组织小肠黏膜损伤程度减轻,酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达量高于未治疗大鼠。结果表明缺血-再灌注损伤后,酸性成纤维细胞生长因子干预可上调酸性成纤维细胞生长因子受体2及细胞外调节蛋白激酶的表达,提示外源性酸性成纤维细胞生长因子通过促进内源性酸性成纤维细胞生长因子受体2和细胞外调节蛋白激酶的生成可能是其参与内脏损伤修复的机制之一。     

Extracellular signal-regulated kinase activation during renal ischemia/reperfusion mediates focal adhesion dissolution and renal injury

Acute renal failure due to ischemia/reperfusion involves disruption of integrin-mediated cellular adhesion and activation of the extracellular signal-regulated kinase (ERK) pathway. The dynamics of focal adhesion organization and phosphorylation during ischemia/reperfusion in relation to ERK activation are unknown. In control kidneys, protein tyrosine-rich focal adhesions, containing focal adhesion kinase, paxillin, and talin, were present at the basolateral membrane of tubular cells and colocalized with short F-actin stress fibers. Unilateral renal ischemia/reperfusion caused a reversible protein dephosphorylation and loss of focal adhesions. The focal adhesion protein phosphorylation rebounded in a biphasic manner, in association with increased focal adhesion kinase, Src, and paxillin tyrosine phosphorylation. Preceding phosphorylation of these focal adhesion proteins, reperfusion caused increased phosphorylation of ERK. The specific mitogen-activated protein kinase kinase 1/2 inhibitor U0126 prevented ERK activation and attenuated focal adhesion kinase, paxillin, and Src phosphorylation, focal adhesion restructuring, and ischemia/reperfusion-induced renal injury. We propose a model whereby ERK activation enhanced protein tyrosine phosphorylation during ischemia/reperfusion, thereby driving the dynamic dissolution and restructuring of focal adhesions and F-actin cytoskeleton during reperfusion and renal injury.     

PI3-K/Akt信号通路对阿尔茨海默病神经元凋亡的调节作用

磷脂酰肌醇3-激酶(PI3-K/Akt)途径是细胞内重要的促细胞存活通路之一,PI3-K被细胞外信号活化后,激活下游蛋白激酶Akt。在阿尔茨海默病(AD)的发病过程中,凋亡相关基因Bad、GSK-3、转录因子家族、caspases家族等参与了神经元的凋亡,导致神经元的大量丢失。而活化的Akt通过磷酸化Bad、GSK-3、转录因子家族、IB、caspases等使促凋亡基因失活,从而起到抑制神经元凋亡及促进神经元存活的作用,进而减少AD神经元的大量丢失,改善AD的病理变化。     

Hypothermia differentially increases extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun terminal kinase activation in the hippocampus during reperfusion after asphyxial cardiac arrest

Mitogen-activated protein kinases are signal transduction mediators that have been implicated in cell survival and cell death. This study characterized the activation of pathways in the hippocampus during reperfusion after global cerebral ischemia, as well as the influence of a regimen of hypothermia that reduces ischemic cell death in the hippocampus. Circulatory arrest was induced in rats by 8 min of asphyxia. Relative levels of phosphorylated and total extracellular signal-regulated kinase, stress-activated protein kinase/c-Jun N-terminal kinase and p38 mitogen-activated protein kinase were measured in the hippocampus after 6, 12 or 24h of reperfusion using immunoblotting. Asphyxia induced a progressive increase in phosphorylated extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun N-terminal kinase, but no change in phosphorylated p38 mitogen-activated protein kinase. Induction of mild hypothermia (33 degrees C) during reperfusion increased extracellular signal-regulated kinase phosphorylation and produced a smaller increase in stress-activated protein kinase/c-Jun N-terminal kinase phosphorylation at 24h. Hypothermia did not alter extracellular signal-regulated kinase activation in rats not subjected to ischemia. Extracellular signal-regulated kinase activation was associated with an increase in phosphorylation of the mitogen-activated protein kinase kinase 1/2, and was inhibited by administration of the specific mitogen-activated protein kinase kinase 1/2 inhibitor SL327. Immunohistochemical staining showed an increase in active extracellular signal-regulated kinase in the CA1, CA2, CA3 and dentate gyrus regions of the hippocampus after ischemia and reperfusion. In contrast, active stress-activated protein kinase/c-Jun N-terminal kinase immunoreactivity was most intense in the CA3 and dentate gyrus regions.These data demonstrate that both extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun N-terminal kinase pathways are activated during the first 24h of reperfusion after global cerebral ischemia, and that hypothermia increases the activation of extracellular signal-regulated kinase relative to stress-activated protein kinase/c-Jun N-terminal kinase. Thus, an increase in extracellular signal-regulated kinase activation may be associated with improved neuronal survival after ischemic injury.     

Various protein kinases regulate human sperm acrosome reaction and the associated phosphorylation of Tyr residues and of the Thr-Glu-Tyr motif

Acrosome reaction (AR) is an exocytotic process of fundamental importance for the spermatozoon to fertilize the oocyte. The mechanisms mediating this process are only partially defined. The aim of the present study was to investigate the role of various kinases and the extracellular signal-regulated kinase (ERK) pathway in the induction of the AR and associated phosphorylation of tyrosine (Tyr) residues and of the threonine-glutamic acid-tyrosine (Thr-Glu-Tyr) motif that occurs in 80 and 105 kDa proteins (p80/p105). Human spermatozoa were capacitated and AR was induced with lysophosphatidylcholine in the presence of inhibitors of various kinases and of the ERK pathway. Phosphorylation of Tyr and of Thr-Glu-Tyr peaked 15 min after the induction of the AR. Both phosphorylations were prevented by inhibitors of protein kinase C, MEK, phosphoinositide 3-kinase and Akt but not by protein kinase A inhibitors. Phosphorylation of Thr-Glu-Tyr, but not Tyr, was decreased by inhibitors of protein tyrosine kinase and Grb2-SH2. All the inhibitors prevented lysophosphatidylcholine-induced AR, indicating the involvement of PKC, PKA, PTK, PI3K, Akt and the ERK pathway. These results show that phosphorylation of Tyr and Thr-Glu-Tyr are associated with the AR and are differently regulated by the various kinases emphasing the complexity of this process.     

Cortical neurons develop insulin resistance and blunted Akt signaling: a potential mechanism contributing to enhanced ischemic injury in diabetes

Patients with diabetes are at higher risk of stroke and experience increased morbidity and mortality after stroke. We hypothesized that cortical neurons develop insulin resistance, which decreases neuroprotection via circulating insulin and insulin-like growth factor-I (IGF-I). Acute insulin treatment of primary embryonic cortical neurons activated insulin signaling including phosphorylation of the insulin receptor, extracellular signal-regulated kinase (ERK), Akt, p70S6K, and glycogen synthase kinase-3β (GSK-3β). To mimic insulin resistance, cortical neurons were chronically treated with 25?mM glucose, 0.2?mM palmitic acid (PA), or 20?nM insulin before acute exposure to 20?nM insulin. Cortical neurons pretreated with insulin, but not glucose or PA, exhibited blunted phosphorylation of Akt, p70S6K, and GSK-3β with no change detected in ERK. Inhibition of the phosphatidylinositol 3-kinase (PI3-K) pathway during insulin pretreatment restored acute insulin-mediated Akt phosphorylation. Cortical neurons in adult BKS-db/db mice exhibited higher basal Akt phosphorylation than BKS-db(+) mice and did not respond to insulin. Our results indicate that prolonged hyperinsulinemia leads to insulin resistance in cortical neurons. Decreased sensitivity to neuroprotective ligands may explain the increased neuronal damage reported in both experimental models of diabetes and diabetic patients after ischemia-reperfusion injury.     

Maintenance of hepatic sinusoidal endothelial cell phenotype in vitro using organ-specific extracellular matrix scaffolds

Sinusoidal endothelial cells (SECs) are notoriously difficult to culture in vitro. SECs represent a highly specialized endothelial cell (EC) population, and traditional methods of SEC isolation from the liver initiate a process of SEC dedifferentiation. Acellular extracellular matrix (ECM) scaffolds were investigated in a physiologically relevant in vitro culture model for their ability to maintain SEC phenotype. The cell culture model used SECs only or a coculture of SECs with hepatocytes on ECM substrates derived from the liver (L-ECM), bladder (UBM-ECM), or small intestine submucosa (SIS-ECM). The effect of the ECM substrate upon SEC dedifferentiation was evaluated using scanning electron microscopy (SEM) and confocal microscopy. When SECs alone were cultured on uncoated glass slides, collagen I, UBM-ECM, or SIS-ECM, SECs showed signs of dedifferentiation after 1 day. In contrast, SECs alone cultured on L-ECM maintained their differentiated phenotype for at least 3 days, indicated by the presence of many fenestrations on SEC surface, expression of anti-rat hepatic sinusoidal endothelial cells mouse IgG MoAb (SE-1), and lack of expression of CD31. When SECs were cocultured with hepatocytes on any of the ECM scaffolds, the SECs maintained a near-normal fenestrated phenotype for at least 1 day. However, SEM revealed that the shape, size, frequency, and organization of the fenestrations varied greatly depending on ECM source. At all time points, SECs cocultured with hepatocytes on L-ECM maintained the greatest degree of differentiation. The present study demonstrated that the acellular ECM scaffold derived from the liver maintained SEC differentiation in culture longer than any of the tested substrate materials. The replacement of complex tissues and 3-dimensional organs may require specialized scaffolds to support multiple, functional cell phenotypes.     

Activation of p42 mitogen-activated protein kinase by arachidonic acid and trans-1-amino-cyclopentyl-1,3-dicarboxylate impacts on long-term potentiation in the dentate gyrus in the rat: analysis of age-related changes

Maintenance of long-term potentiation in perforant path–granule cell synapses is associated with an increase in glutamate release, which we have suggested relies on an interaction between arachidonic acid and the metabotropic glutamate receptor agonist, trans-1-amino-cyclopentyl-1,3-dicarboxylate (ACPD). Evidence suggests that this interaction is dependent on stimulation of tyrosine kinase, which phosphorylates and activates phospholipase Cγ. In this study, we demonstrate that arachidonic acid and ACPD stimulate tyrosine phosphorylation of a protein of about 40,000 mol. wt and further analysis, using a specific antibody, suggested that this may be extracellular signal-regulated kinase, one member of the family of mitogen-activated protein kinases. Activity of extracellular signal-regulated kinase was increased by arachidonic acid and ACPD in vitro, but it was also increased by induction of long-term potentiation in perforant path–granule cell synapses. A role for extracellular signal-regulated kinase in long-term potentiation was supported by the observation that expression of long-term potentiation, as well as the associated increases in endogenous glutamate release and extracellular signal-regulated kinase activation, were inhibited by pretreatment with the mitogen-activated protein kinase inhibitor, PD98059, while PD98059 pretreatment inhibited the interaction between arachidonic acid and ACPD on glutamate release. An age-related decrease in extracellular signal-regulated kinase activity was observed in the dentate gyrus, and there was no evidence of increased extracellular signal-regulated kinase activity or endogenous glutamate release in tissue prepared from aged rats in which long-term potentiation was compromised.

The evidence is consistent with the view that increased activation of extracellular signal-regulated kinase plays a role in long-term potentiation, and that activation of this kinase relies on the interaction between arachidonic acid and ACPD.     

Japanese encephalitis virus infection stimulates Src tyrosine kinase in neuron/glia

Japanese encephalitis virus (JEV) is a neurotropic virus. The clinically manifestation of JEV-induced encephalitis is characterized by the brain inflammation and neuronal dysfunction and/or destruction. Currently, the cellular signaling molecules that underlie JEV-induced cerebral inflammation and cellular alterations are not well understood. Protein tyrosine phosphorylation events are key regulators of cellular signaling processes, including inflammation. We investigated whether Src protein tyrosine kinase (PTK) function in JEV-induced cellular changes in neuron/glia cultures. JEV infection modulated tyrosine phosphorylation events. Src PTK was hyperphosphorylated at the early stage of infection. Biochemical studies demonstrated that both inhibitors of the Src family PTK and Ras attenuated JEV-induced extracellular signal-regulated kinase (ERK) activation. Our results further revealed that PTK, Ras, and ERK inhibitors effectively suppressed JEV-induced pro-inflammatory cytokine expression and neurotoxicity. Pharmacological studies suggested that microglia secreted pro-inflammatory cytokine via Src/Ras/ERK pathway in responding to JEV infection. Another interesting observation was that nonstructural protein 3 (NS3) was able to interact with Src and showed tyrosine phosphorylation. However, the biological consequences of their interaction and exact control of NS3 tyrosine phosphorylation required further investigation. Our results suggest that the Src/Ras/ERK signaling cascade is involved in JEV-induced pro-inflammatory cytokine expression and neurotoxicity.     

Activation of phosphatidylinositol 3-kinase/protein kinase B pathway by a vanadyl compound mediates its neuroprotective effect in mouse brain ischemia

We previously reported that orthovanadate composed of vanadate (V(5+)) activates phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling through inhibition of protein tyrosine phosphatases, thereby eliciting neuroprotection in brain ischemia/reperfusion injury. However, therapeutic doses of orthovanadate are associated with diarrhea due to inhibition of ATPase. By contrast, vanadyl (V(4+)) organic compounds show low cytotoxicity. Since both vanadate and vanadyl inhibit protein tyrosine phosphatases, we tested whether bis(1-oxy-2-pyridinethiolato)oxovanadium(IV) [VO(OPT)] in a vanadyl form elicits a neuroprotection in brain ischemia. In a mouse transient middle cerebral artery occlusion (MCAO) model, pre- and post-treatments with VO(OPT) significantly reduced infarct volume in a dose-dependent manner. Like orthovanadate, activation of the PI3K/Akt pathway mediated neuroprotective action. VO(OPT) treatment inhibited reduced Akt phosphorylation at Ser-473 following brain ischemia and restored decreased phosphorylation of forkhead box class O (FOXO) family members such as FKHR, FKHRL1, and AFX. Consistent with inhibition of FOXO dephosphorylation, VO(OPT) treatment blocked elevated expression of Fas-ligand, Bim and active caspase-3 24 h after ischemia/reperfusion. Taken together, a vanadyl compound, VO(OPT) elicits neuroprotective effects on brain ischemia/reperfusion injury without apparent side effects.     

Involvement of MAP kinases in apoptosis of macrophage treated with Trichomonas vaginalis

A primitive protozoan parasite Trichomonas vaginalis selectively activates the signal transduction pathways in macrophages (RAW264.7). This study evaluated the correlation of these signaling pathways and T. vaginalis-induced cell apoptosis. In macrophages infected with T. vaginalis, apoptosis was assessed on the basis of DNA fragmentation on agarose gel electrophoresis. Infection of macrophages with T. vaginalis induced tyrosine phosphorylation of several proteins. Infected cells with T. vaginalis were shown to associate with phosphorylation of the extracellular signal-regulated (ERK)1/2 kinase, p38, c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinases on Western blot analysis. The present finding also demonstrated a link between the ERK1/2, JNK and p38 apoptotic pathways that was modulated by T. vaginalis infection.     

Extracellular signal-regulated kinase activation by Neisseria gonorrhoeae downregulates epithelial cell proapoptotic proteins Bad and Bim

Neisseria gonorrhoeae expressing type IV pili (Tfp) activates extracellular signal-regulated kinase (ERK) and induces a cytoprotective state in the epithelial cell in a manner that is enhanced by pilT. As the ERK signaling pathway is well-known for its role in cytoprotection and cell survival, we tested the hypothesis that ERK is involved in producing this cytoprotective effect. Inhibiting ERK activation prior to infection attenuated the ability of these bacteria to induce cytoprotection. Activated ERK specifically targeted two proapoptotic Bcl-2 homology domain 3 (BH3)-only proteins, Bim and Bad, for downregulation at the protein level. Bim downregulation occurred through the proteasome. ERK, in addition, inactivated Bad by triggering its phosphorylation at Ser112. Finally, reducing the level of either Bad or Bim alone by small interfering RNA was sufficient to protect uninfected cells from staurosporine-induced apoptosis. We conclude that Tfp-induced cytoprotection is due in part to ERK-dependent modification and/or downregulation of proapoptotic proteins Bad and Bim.     

Platelet-activating factor-induced synaptic facilitation is associated with increased calcium/calmodulin-dependent protein kinase II,protein kinase C and extracellular signal-regulated kinase activities in the rat hippocampal CA1 region

Platelet-activating factor (PAF) is an important inflammatory lipid mediator affecting neural plasticity. In the present study, we demonstrated how PAF affects synaptic efficacy through activation of protein kinases in the rat hippocampal CA1 region. In cultured hippocampal neurons, 10 to 1000 nM PAF stimulated autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) and phosphorylation of synapsin I and myristoylated alanine-rich protein kinase C substrate (MARCKS). In hippocampal CA1 slices, field excitatory postsynaptic potentials (fEPSPs) induced by stimulation of the Schaffer collateral/commissural pathways were significantly increased 10–50 min after exposure to 100 to 1000 nM PAF. Immunoblotting analysis showed that 100 nM PAF treatment for 10 or 50 min significantly and persistently increased CaMKII autophosphorylation in the hippocampal CA1 region. Increased protein kinase Cα (PKCα) autophosphorylation was also seen at the same time point after PAF exposure. By contrast, extracellular signal-regulated kinase (ERK) phosphorylation was slightly but significantly increased at 10 min after PAF exposure. Consistent with increased CaMKII autophosphorylation, AMPA-type glutamate receptor subunit 1 (GluR1) (Ser-831) phosphorylation as a CaMKII postsynaptic substrate significantly increased after 10 or 50 min of treatment, whereas synapsin I (Ser-603) phosphorylation as a presynaptic substrate increased at 10 min in the hippocampal CA1 region. Phosphorylation of MARCKS (Ser-152/156) and NMDA receptor subunit 1 (NR1) (Ser-896) as PKCα substrates also significantly increased after 10 min but had not further increased by 50 min in the CA1 region. Increased of fEPSPs induced by PAF treatment completely and/or partly inhibited by KN93 and/or U0126 treatment. These results suggest that PAF induces synaptic facilitation through activation of CaMKII, PKC and ERK in the hippocampal CA1 region.     

Short-term delay of Fas-stimulated apoptosis by GM-CSF as a result of temporary suppression of FADD recruitment in neutrophils: evidence implicating phosphatidylinositol 3-kinase and MEK1-ERK1/2 pathways downstream of classical protein kinase C

Granulocyte/macrophage colony-stimulating factor (GM-CSF) inhibits Fas-induced apoptosis of neutrophils. However, the exact step in the apoptotic pathway blocked by GM-CSF remained unclear. Here, we found that pretreatment of neutrophils with GM-CSF inhibits the recruitment of Fas-associated protein with death domain (FADD) to Fas, abolishing the formation of the death-inducing signaling complex required for Fas-induced apoptosis. Two-dimensional electrophoresis revealed that GM-CSF modifies the ratio of FADD subspecies. These GM-CSF-triggered changes were abrogated, and Fas-induced apoptosis was restored by an inhibitor of classical protein kinase C (PKC), Go6976, and by the combination of a phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294002, and an inhibitor of mitogen-activated protein kinase kinase (MEK)1, PD98059. Go6976 blocked GM-CSF-elicited phosphorylation of Akt/PKB and extracellular signal-regulated kinase (ERK)1/2. These results indicated that GM-CSF suppresses Fas-induced neutrophil apoptosis by inhibiting FADD binding to Fas, through redundant actions of PI-3K and MEK1-ERK1/2 pathways downstream of classical PKC.     

ERK5对体外血小板活化及在体血栓的影响

目的:探讨细胞外信号调节激酶5(ERK5)对体外血小板聚集及在体血栓的影响及机制。方法:采用Western blot对人血小板中ERK5的表达及其在血小板活化后的磷酸化水平进行检测;采用血小板聚集仪检测ERK5特异性抑制剂XMD8-92对血小板聚集及致密颗粒释放的影响;采用Fe Cl3颈动脉血栓模型检测ERK5对在体血栓的影响;采用Western blot检测XMD8-92对蛋白激酶B(Akt)和人第10号染色体缺失的磷酸酶及张力蛋白同源蛋白(PTEN)磷酸化的影响。结果:人血小板中存在ERK5的稳定表达,其磷酸化水平在血小板活化后显著升高(P0.05)。XMD8-92可抑制多种血小板激活剂引起的血小板聚集和致密颗粒释放(P0.05)。Western blot结果表明,XMD8-92可通过下调PTEN Ser370位点磷酸化而增强PTEN的活性,从而抑制Akt的磷酸化,这种抑制效果也通过血小板特异PTEN基因敲除小鼠得到了验证。在体血栓研究表明,XMD8-92经尾静脉给药,可显著延长小鼠第一次颈动脉血栓的形成时间。结论:ERK5可通过影响PTEN的磷酸化调节Akt的活化,进而影响到体外血小板的聚集和在体血栓的形成。     

The B cell receptor promotes B cell activation and proliferation through a non-ITAM tyrosine in the Igalpha cytoplasmic domain

In addition to the tyrosines of the Igalpha and beta immunoreceptor tyrosine-based activation motifs (ITAMs), the evolutionarily conserved Igalpha non-ITAM tyrosine 204 becomes phosphorylated upon antigen recognition by the B cell receptor (BCR). Here we demonstrate that splenic B cells from mice with a targeted mutation of Igalpha Y204 exhibited an isolated defect in T cell-independent B cell activation, proliferation, and antibody response upon BCR engagement, yet normal BCR capping, antigen internalization, antigen presentation, and T cell-dependent antibody production. Mutant B cells, present in normal numbers, exhibited unimpaired BCR-induced spleen tyrosine kinase (Syk) phosphorylation but reduced B cell linker protein (BLNK) phosphorylation, calcium flux, and nuclear factor kappaB (NFkappaB), c-jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) activation. These results suggest that Igalpha non-ITAM tyrosine 204 promotes a distinct cellular response, namely T-independent B cell proliferation and differentiation via phosphorylation of the adaptor BLNK.     

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.