Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB le...Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.展开更多
Objective To investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910...Objective To investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910 cells.Methods Activation of the ERK1/2 and p38 was detected by Western blotting using the antibodies against the total ERK1/2 and p38 mitogen-activated protein kinases (MAPKs) protein and the phosphorylated forms of them. Results Dex could suppress the activation of ERK1/2, while enhance the activation of p38 rapidly and strongly in a dose- and time- dependent manner. Neither effect could be blocked by RU486, the antagonist of glucocorticoid receptor (GR).Conclusion Dex has rapid effects on the activation of ERK1/2 and p38, and these effects are not mediated by GR.展开更多
Previous studies have shown that CCL2(C-C motif chemokine ligand 2)induces chronic pain,but the exact mechanisms are still unknown.Here,we established models to explore the potential mechanisms.Behavioral experiments ...Previous studies have shown that CCL2(C-C motif chemokine ligand 2)induces chronic pain,but the exact mechanisms are still unknown.Here,we established models to explore the potential mechanisms.Behavioral experiments revealed that an antagonist of extracellular signal-regulated kinase(ERK)inhibited not only CCL2-induced inflammatory pain,but also pain responses induced by complete Freund’s adjuvant.We posed the question of the intracellular signaling cascade involved.Subsequent experiments showed that CCL2 up-regulated the expression of phosphorylated ERK(pERK)and N-methyl D-aspartate receptor[NMDAR]subtype 2B(GluN2B);meanwhile,antagonists of CCR2 and ERK effectively reversed these phenomena.Whole-cell patchclamp recordings revealed that CCL2 enhanced the NMDAR-induced currents via activating the pERK pathway,which was blocked by antagonists of GluN2B and ERK.In summary,we demonstrate that CCL2 directly interacts with CCR2 to enhance NMDAR-induced currents,eventually leading to inflammatory pain mainly through the CCL2-CCR2-pERK-GluN2B pathway.展开更多
We previously demonstrated that overexpression of tropomyosin receptor kinase A(TrkA)promotes the survival and Schwann celllike differentiation of bone marrow stromal stem cells in nerve grafts,thereby enhancing the r...We previously demonstrated that overexpression of tropomyosin receptor kinase A(TrkA)promotes the survival and Schwann celllike differentiation of bone marrow stromal stem cells in nerve grafts,thereby enhancing the regeneration and functional recovery of the peripheral nerve.In the present study,we investigated the molecular mechanisms underlying the neuroprotective effects of TrkA in bone marrow stromal stem cells seeded into nerve grafts.Bone marrow stromal stem cells from Sprague-Dawley rats were infected with recombinant lentivirus vector expressing rat TrkA,TrkA-shRNA or the respective control.The cells were then seeded into allogeneic rat acellular nerve allografts for bridging a 1-cm right sciatic nerve defect.Then,8 weeks after surgery,hematoxylin and eosin staining showed that compared with the control groups,the cells and fibers in the TrkA overexpressing group were more densely and uniformly arranged,whereas they were relatively sparse and arranged in a disordered manner in the TrkA-shRNA group.Western blot assay showed that compared with the control groups,the TrkA overexpressing group had higher expression of the myelin marker,myelin basic protein and the axonal marker neurofilament 200.The TrkA overexpressing group also had higher levels of various signaling molecules,including TrkA,pTrkA(Tyr490),extracellular signal-regulated kinases 1/2(Erkl/2),pErk1/2(Thr202/Tyr204),and the anti-apoptotic proteins Bcl-2 and Bcl-xL.In contrast,these proteins were downregulated,while the pro-apoptotic factors Bax and Bad were upregulated,in the TrkA-shRNA group.The levels of the TrkA effectors Akt and pAkt(Ser473)were not different among the groups.These results suggest that TrkA enhances the survival and regenerative capacity of bone marrow stromal stem cells through upregulation of the Erk/Bcl-2 pathway.All procedures were approved by the Animal Ethical and Welfare Committee of Shenzhen University,China in December 2014(approval No.AEWC-2014-001219).展开更多
The activation of the mitogen-activated protein(MAP) kinases extracellular signal-regulated kinase(ERK)1/2 was traditionally used as a readout of signaling of G protein-coupled receptors(GPCRs) via arrestins, as oppos...The activation of the mitogen-activated protein(MAP) kinases extracellular signal-regulated kinase(ERK)1/2 was traditionally used as a readout of signaling of G protein-coupled receptors(GPCRs) via arrestins, as opposed to conventional GPCR signaling via G proteins. Several recent studies using HEK293 cells where all G proteins were genetically ablated or inactivated, or both non-visual arrestins were knocked out, demonstrated that ERK1/2 phosphorylation requires G protein activity, but does not necessarily require the presence of non-visual arrestins. This appears to contradict the prevailing paradigm. Here we discuss these results along with the recent data on gene edited cells and arrestinmediated signaling. We suggest that there is no real controversy. G proteins might be involved in the activation of the upstream-most MAP3Ks, although in vivo most MAP3K activation is independent of heterotrimeric G proteins, being initiated by receptor tyrosine kinases and/or integrins. As far as MAP kinases are concerned, the best-established role of arrestins is scaffolding of the three-tiered cascades(MAP3K-MAP2 K-MAPK). Thus, it seems likely that arrestins, GPCRbound and free, facilitate the propagation of signals in these cascades, whereas signal initiation via MAP3K activation may be independent of arrestins. Different MAP3Ks are activated by various inputs, some of which are mediated by G proteins, particularly in cell culture, where we artificially prevent signaling by receptor tyrosine kinases and integrins, thereby favoring GPCR-induced signaling. Thus, there is no reason to change the paradigm: Arrestins and G proteins play distinct non-overlapping roles in cell signaling.展开更多
Objective:To investigate the effects of Korean Magnolia obovata crude extract(KME)on plateletderived growth factor(PDGF)-BB-induced proliferation and migration of vascular smooth muscle cells(VSMCs).Methods:KME compos...Objective:To investigate the effects of Korean Magnolia obovata crude extract(KME)on plateletderived growth factor(PDGF)-BB-induced proliferation and migration of vascular smooth muscle cells(VSMCs).Methods:KME composition was analyzed by high-performance liquid chromatography(HPLC).VSMCs were isolated from the aorta of a Sprague-Dawley rat,incubated in serum free-Dulbecco's modified Eagle's medium in the presence or absence of KME(10,30,100,and 300(xg/mL),then further treated with PDGF-BB(10 ng/mL).VSMC proliferation was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and VSMC migration was determined using the Boyden chamber and scratch wound healing assays.Western blot analysis was used to detect phosphorylation of extracellular signal-regulated protein kinases 1 and 2(p-ERK1/2),protein kinase B(p-Akt),and stress-activated protein kinase/c-Jun NH2-terminal kinase(p-SAPK/JNK).The antimigration and proliferation effects of KME were tested using aortic sprout outgrowth.Results:The HPLC analysis identified honokiol(0.45 mg/g)and magnolol(0.34 mg/g)as the major components of KME.KME(30,100,and 300μg/m L)significantly decreased the proliferation and migration of PDGF-BB-stimulated(10 ng/mL)VSMCs and the PDGF-BB-induced phosphorylation of EKR1/2,Akt,and SAPK/JNK(P<0.05).Furthermore,PDGF-BBinduced VSMCs treated with 300μg/m L of KME showed reduction in aortic sprout outgrowth.Conclusion:KME could inhibit abnormal proliferation and migration of VSMCs by down-regulating the phosphorylation of EKR1/2 and Akt.Thus,KME might be a functional food for preventing vascular disorders.展开更多
基金supported by Research Start-up Funding of Shenzhen Traditional Chinese Medicine Hospital,No.2021-07(to FB)Sanming Project of Medicine in Shenzhen,No.SZZYSM 202111011(to XDQ and FB)+1 种基金Key Discipline Established by Zhejiang Province,Jiaxing City Jointly-Pain Medicine,No.2019-ss-ttyx(to LSX)Jiaxing Key Laboratory of Neurology and Pain Medicine,No.[2014]81(to LSX)。
文摘Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.
文摘Objective To investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910 cells.Methods Activation of the ERK1/2 and p38 was detected by Western blotting using the antibodies against the total ERK1/2 and p38 mitogen-activated protein kinases (MAPKs) protein and the phosphorylated forms of them. Results Dex could suppress the activation of ERK1/2, while enhance the activation of p38 rapidly and strongly in a dose- and time- dependent manner. Neither effect could be blocked by RU486, the antagonist of glucocorticoid receptor (GR).Conclusion Dex has rapid effects on the activation of ERK1/2 and p38, and these effects are not mediated by GR.
基金grants from the National Natural Science Foundation of China(81870867,31671088,31471059,and 81502102)the Natural Science Foundation of Shaanxi Province,China(2019SF-071 and 2017ZDJC-01)。
文摘Previous studies have shown that CCL2(C-C motif chemokine ligand 2)induces chronic pain,but the exact mechanisms are still unknown.Here,we established models to explore the potential mechanisms.Behavioral experiments revealed that an antagonist of extracellular signal-regulated kinase(ERK)inhibited not only CCL2-induced inflammatory pain,but also pain responses induced by complete Freund’s adjuvant.We posed the question of the intracellular signaling cascade involved.Subsequent experiments showed that CCL2 up-regulated the expression of phosphorylated ERK(pERK)and N-methyl D-aspartate receptor[NMDAR]subtype 2B(GluN2B);meanwhile,antagonists of CCR2 and ERK effectively reversed these phenomena.Whole-cell patchclamp recordings revealed that CCL2 enhanced the NMDAR-induced currents via activating the pERK pathway,which was blocked by antagonists of GluN2B and ERK.In summary,we demonstrate that CCL2 directly interacts with CCR2 to enhance NMDAR-induced currents,eventually leading to inflammatory pain mainly through the CCL2-CCR2-pERK-GluN2B pathway.
基金supported by the National Natural Science Foundation of China,No.81372041(to DW),and No.81801220(to MGZ)
文摘We previously demonstrated that overexpression of tropomyosin receptor kinase A(TrkA)promotes the survival and Schwann celllike differentiation of bone marrow stromal stem cells in nerve grafts,thereby enhancing the regeneration and functional recovery of the peripheral nerve.In the present study,we investigated the molecular mechanisms underlying the neuroprotective effects of TrkA in bone marrow stromal stem cells seeded into nerve grafts.Bone marrow stromal stem cells from Sprague-Dawley rats were infected with recombinant lentivirus vector expressing rat TrkA,TrkA-shRNA or the respective control.The cells were then seeded into allogeneic rat acellular nerve allografts for bridging a 1-cm right sciatic nerve defect.Then,8 weeks after surgery,hematoxylin and eosin staining showed that compared with the control groups,the cells and fibers in the TrkA overexpressing group were more densely and uniformly arranged,whereas they were relatively sparse and arranged in a disordered manner in the TrkA-shRNA group.Western blot assay showed that compared with the control groups,the TrkA overexpressing group had higher expression of the myelin marker,myelin basic protein and the axonal marker neurofilament 200.The TrkA overexpressing group also had higher levels of various signaling molecules,including TrkA,pTrkA(Tyr490),extracellular signal-regulated kinases 1/2(Erkl/2),pErk1/2(Thr202/Tyr204),and the anti-apoptotic proteins Bcl-2 and Bcl-xL.In contrast,these proteins were downregulated,while the pro-apoptotic factors Bax and Bad were upregulated,in the TrkA-shRNA group.The levels of the TrkA effectors Akt and pAkt(Ser473)were not different among the groups.These results suggest that TrkA enhances the survival and regenerative capacity of bone marrow stromal stem cells through upregulation of the Erk/Bcl-2 pathway.All procedures were approved by the Animal Ethical and Welfare Committee of Shenzhen University,China in December 2014(approval No.AEWC-2014-001219).
基金Supported by National Institutes of Health RO1 grants,No.EY011500National Institutes of Health R35 grants,No.GM122491Cornelius Vanderbilt Endowed Chair(Vanderbilt University),No.NS065868(to Gurevich VV)and No.DA030103(to Gurevich EV)
文摘The activation of the mitogen-activated protein(MAP) kinases extracellular signal-regulated kinase(ERK)1/2 was traditionally used as a readout of signaling of G protein-coupled receptors(GPCRs) via arrestins, as opposed to conventional GPCR signaling via G proteins. Several recent studies using HEK293 cells where all G proteins were genetically ablated or inactivated, or both non-visual arrestins were knocked out, demonstrated that ERK1/2 phosphorylation requires G protein activity, but does not necessarily require the presence of non-visual arrestins. This appears to contradict the prevailing paradigm. Here we discuss these results along with the recent data on gene edited cells and arrestinmediated signaling. We suggest that there is no real controversy. G proteins might be involved in the activation of the upstream-most MAP3Ks, although in vivo most MAP3K activation is independent of heterotrimeric G proteins, being initiated by receptor tyrosine kinases and/or integrins. As far as MAP kinases are concerned, the best-established role of arrestins is scaffolding of the three-tiered cascades(MAP3K-MAP2 K-MAPK). Thus, it seems likely that arrestins, GPCRbound and free, facilitate the propagation of signals in these cascades, whereas signal initiation via MAP3K activation may be independent of arrestins. Different MAP3Ks are activated by various inputs, some of which are mediated by G proteins, particularly in cell culture, where we artificially prevent signaling by receptor tyrosine kinases and integrins, thereby favoring GPCR-induced signaling. Thus, there is no reason to change the paradigm: Arrestins and G proteins play distinct non-overlapping roles in cell signaling.
文摘Objective:To investigate the effects of Korean Magnolia obovata crude extract(KME)on plateletderived growth factor(PDGF)-BB-induced proliferation and migration of vascular smooth muscle cells(VSMCs).Methods:KME composition was analyzed by high-performance liquid chromatography(HPLC).VSMCs were isolated from the aorta of a Sprague-Dawley rat,incubated in serum free-Dulbecco's modified Eagle's medium in the presence or absence of KME(10,30,100,and 300(xg/mL),then further treated with PDGF-BB(10 ng/mL).VSMC proliferation was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and VSMC migration was determined using the Boyden chamber and scratch wound healing assays.Western blot analysis was used to detect phosphorylation of extracellular signal-regulated protein kinases 1 and 2(p-ERK1/2),protein kinase B(p-Akt),and stress-activated protein kinase/c-Jun NH2-terminal kinase(p-SAPK/JNK).The antimigration and proliferation effects of KME were tested using aortic sprout outgrowth.Results:The HPLC analysis identified honokiol(0.45 mg/g)and magnolol(0.34 mg/g)as the major components of KME.KME(30,100,and 300μg/m L)significantly decreased the proliferation and migration of PDGF-BB-stimulated(10 ng/mL)VSMCs and the PDGF-BB-induced phosphorylation of EKR1/2,Akt,and SAPK/JNK(P<0.05).Furthermore,PDGF-BBinduced VSMCs treated with 300μg/m L of KME showed reduction in aortic sprout outgrowth.Conclusion:KME could inhibit abnormal proliferation and migration of VSMCs by down-regulating the phosphorylation of EKR1/2 and Akt.Thus,KME might be a functional food for preventing vascular disorders.
