同型半胱氨酸通过Rho激酶信号通路促进大鼠脑基底动脉平滑肌细胞活力与迁移

目的:探讨同型半胱氨酸(homocysteine,Hcy)对大鼠脑基底动脉平滑肌细胞(basilar arterial smooth muscle cells,BASMCs)活力和迁移的作用及可能的分子机制。方法:分离培养大鼠BASMCs,给予不同浓度的Hcy刺激后,用CCK-8法初步测定细胞活力的变化,Western blot检测Rho激酶信号通路的活性。然后固定Hcy的浓度(1 mmol/L),并采用ROCK抑制剂Y-27632作为工具药对细胞进行处理,流式细胞术检测细胞的周期分布,划痕实验和Transwell实验检测细胞的迁移情况;检测细胞抗氧化酶超氧化物歧化酶(superoxide dismutase,SOD)和谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)的活性以及丙二醛(malondialdehyde,MDA)的水平反映细胞的氧化应激状态。结果:Hcy可浓度依赖性地提高BASMCs的活力,并上调细胞中GTP-RhoA和ROCK2的蛋白表达(P0.05);同浓度的Hcy处理细胞后,48 h处理组的细胞活力显著高于24 h处理组(P0.05)。Hcy处理组BASMCs中S期细胞的比例明显升高,G_0/G_1期细胞的比例显著降低(P0.05);加入Y-27632预处理可显著抑制Hcy处理组BASMCs的G_1/S期转换。划痕实验和Transwell的实验结果显示,Hcy处理组BASMCs的迁移率显著高于对照组;加入Y-27632预处理可抑制Hcy处理组BASMCs的迁移(P0.05)。此外,Hcy可降低BASMCs中SOD和GSH-Px的活性,同时升高MDA的含量;相较Hcy处理组,加入Y-27632预处理后,细胞内SOD和GSH-Px的活性升高,MDA的含量降低(P0.05)。结论:同型半胱氨酸可促进大鼠脑基底动脉平滑肌细胞的活力及迁移,其作用机制可能与激活Rho激酶信号通路并提高细胞内氧化应激的水平有关。     

Rho激酶对大鼠海马神经元CRMPs mRNA表达的调节

目的探讨Rho激酶对大鼠海马神经元CRMPs mRNA表达的调节。方法体外培养新生大鼠海马神经元5d后,用Rho激酶激动剂LPA和抑制剂Y27632改变细胞内Rho激酶的活性,采用突起提取试剂盒提取神经元的突起,检测突起生长的变化,并应用实时荧光定量PCR方法检测CRMPs mRNA的表达。结果对照组细胞突起提取液吸光度值为0.0426±0.0062,用LPA处理后的细胞突起提取液吸光度值较对照组明显降低(P<0.05);Y27632组细胞突起提取液的吸光度值较对照组明显升高(P<0.05)。各基因在培养的大鼠海马神经元中均能检测到,对照组分析显示CRMP 1、2、4、5 mRNA表达水平相近且较高,CRMP3 mRNA表达水平相对较低;LPA处理后,CRMP1与CRMP3 mRNA表达水平与对照组相比明显上调(P<0.05),CRMP5 mRNA表达水平明显下调(P<0.05),CRMP2与CRMP4 mRNA表达水平与对照组相比无明显差异(P>0.05);Y27632处理后,CRMP1与CRMP3 mRNA表达水平与对照组相比明显下调(P<0.05),CRMP2、CRMP4和CRMP5 mRNA表达水平与对照组相比无明显差异(P>0.05)。结论 Rho激酶通过影响CRMP1、CRMP3和CRMP5 mRNA的表达调控神经元突起生长。     

IL-38拮抗RhoA/ROCK信号抑制PDGF-BB诱导的血管平滑肌细胞增殖和迁移

目的探究白细胞介素(IL)-38对血小板源性生长因子-BB(PDGF-BB)诱导的血管平滑肌细胞增殖和迁移的作用和机制。方法将人主动脉血管平滑肌细胞(HA-VSMC)随机分成4组:对照组(不进行任何处理)、PDGF-BB组(加入20 ng/ml重组人PDGF-BB蛋白处理24 h)、PDGF-BB+空质粒组(转染pcDNA3.1空质粒48 h后加入20 ng/ml重组人PDGF-BB蛋白处理24 h)和PDGF-BB+IL-38组(转染pcDNA3.1-IL-38质粒48 h后加入20 ng/ml重组人PDGF-BB蛋白刺激24 h)。MTT法检测细胞活力、Transwell检测细胞迁移、Western blot检测增殖细胞核抗原(PCNA)、RhoA、Rho相关蛋白激酶(ROCK)1、ROCK2、肌球蛋白磷酸酶靶标亚基1(MYPT1)和磷酸化MYPT(p-MYPT)蛋白水平的表达。结果与对照组相比,PDGF-BB组中细胞活力,迁移细胞数目,PCNA、RhoA、ROCK1、ROCK2的表达和p-MYPT/MYPT1的值均增加,差异均具有统计学意义(均P0.05);与PDGFBB组相比,PDGF-BB+空质粒组中这些指标变化无统计学意义(均P0.05);与PDGF-BB+空质粒组相比,PDGF-BB+IL-38组中细胞活力,迁移细胞数目,PCNA、RhoA、ROCK1、ROCK2的表达和p-MYPT/MYPT1的值均降低,差异均具有统计学意义(均P0.05)。结论 IL-38能够减弱PDGF-BB诱导的血管平滑肌细胞增殖和迁移,这种作用可能是通过抑制RhoA/ROCK通路活化发挥作用的。     

人参皂甙Rb1通过Rho/Rho激酶通路影响低氧诱导大鼠肺动脉平滑肌细胞增殖及SERT和5-HT_(1B)R表达

目的:观察人参皂甙Rb1对低氧性大鼠肺动脉平滑肌细胞(PASMCs)5-羟色胺转运体(SERT)和5-羟色胺1B受体(5-HT_(1B)R)表达及细胞增殖的影响,并探讨Rho/Rho激酶通路在其中的作用。方法:分离并培养健康雄性SD大鼠PASMCs,随机分为常氧组(normal组)、低氧组(hypoxia组)以及低氧加50、100和200 mg/L人参皂甙Rb1组(HR50、HR100和HR200组),采用CCK-8、Brd U结合流式细胞术、Western blot及RT-PCR等方法,观察大鼠PASMCs的增殖程度以及SERT和5-HT_(1B)R的mRNA和蛋白表达变化;另取PASMCs分为normal组、hypoxia组、HR200组和低氧加Y-27632组(HY组),检测Rho激酶(ROCK1)mRNA表达和肌球蛋白磷酸酶目标亚单位1(MYPT1)磷酸化水平。结果:与normal组比较,hypoxia组PASMCs增殖明显(P0.01);与hypoxia组比较,人参皂甙Rb1可明显抑制PASMCs的增殖(P0.01),并浓度依赖性抑制SERT和5-HT_(1B)R的mRNA与蛋白表达(P0.05);HR200组可明显抑制ROCK1的mRNA表达和MYPT1磷酸化水平(P0.01),与HY组相比较,差异无统计学显著性。结论:低氧能诱导大鼠PASMCs增殖,上调SERT和5-HT_(1B)R表达;人参皂甙Rb1能浓度依赖性抑制这种作用,其机制可能与抑制Rho/Rho激酶通路表达有关。     

“三通针法”电针调控Rho/ROCK(Rho kinase)及MEK/ERK信号通路对脊髓损伤大鼠胞浆型磷脂酶A2的影响

背景:胞浆型磷脂酶A2(cytosolic phospholipase A2,cPLA2)是治疗脊髓损伤的新型策略和靶标,其受RhoA/Rho kinase及MEK/ERK信号通路的调控。而电针可通过调控RhoA/Rho kinase和MEK/ERK信号通路治疗脊髓损伤。目的:探讨电针调控Rho/ROCK(Rho kinase)及MEK/ERK信号通路对脊髓损伤后cPLA2的影响。方法:90只雌性SD大鼠,随机取72只制备脊髓损伤模型,BBB评分后随机分为脊髓损伤组、电针治疗组、U0126治疗组(ERK阻断剂)和Y27632治疗组(ROCK阻断剂),另18只设为假手术组(只进行椎板咬除,但不进行脊髓撞击)。电针治疗组大鼠取大椎、腰阳关以及双侧次髎、足三里进行电针治疗,每天1次,每次20 min,共14次;U0126治疗组和Y27632治疗组分别予以U0126和Y27362隔天1次硬膜下腔注射。治疗结束经BBB评分后处死大鼠,收集脊髓组织,ELISA检测脊髓组织前列腺素E2、血小板活化因子的水平;TUNEL法检测脊髓神经细胞凋亡率;Western blot检测脊髓RhoA、ROCKⅡ、M...     

Rho激酶抑制剂Y-27632对MRL/lpr狼疮小鼠的保护作用北大核心CSCD

目的探讨Rho激酶抑制剂Y-27632对MRL/lpr狼疮小鼠的保护作用机制。方法 MRL/lpr狼疮小鼠20只随机分为MRL/lpr对照组、5 mg/kg Y-27632处理组,每组10只;野生型对照组C57BL/6小鼠10只。采用ELISA检测各组小鼠血清、脾脏组织中超氧化物歧化酶(SOD)、丙二醛(MDA)水平,ELISA检测血清核因子κB(NF-κB)相关炎症因子白细胞介素6(IL-6)、IL-1β、肿瘤坏死因子α(TNF-α)含量;采用Western blot法检测各组小鼠脾脏组织中硫氧还蛋白结合蛋白(Txnip)/硫氧还蛋白(Trx)、丝裂原激活蛋白激酶(MAPK)相关蛋白胞外信号调节激酶(ERK)、c-Jun氨基末端激酶(JNK)和p38MAPK以及NF-κB的水平;Western blot法检测各组小鼠脾脏T淋巴细胞Txnip、p38MAPK、NF-κB蛋白水平;ELISA检测T淋巴细胞上清液IL-6、IL-1β、TNF-α水平。结果 Y-27632提高MRL/lpr狼疮小鼠血清及脾脏组织SOD水平;降低血清及脾脏组织MDA水平;降低血清、脾脏组织和脾脏T淋巴细胞上清液IL-6、IL-1β、TNF-α水平;抑制脾脏和脾脏T淋巴细胞Txnip、MAPK相关蛋白ERK、JNK和p38MAPK以及NF-κB表达,增加Trx含量。结论 Rho激酶抑制剂Y-27632对MRL/lpr狼疮小鼠有保护作用。     

青蒿琥酯通过抑制ERK1/2蛋白活化负性调控HSC-T6细胞cyclin D1的表达和AP-1活性

目的: 通过观察青蒿琥酯(artesunate,Art)对肝星状细胞(hepatic stellate cells,HSCs)细胞外信号调节蛋白激酶1/2(extracellular signal-regulated kinase 1/2,ERK1/2)、激活蛋白1(activator protein 1,AP-1)和细胞周期蛋白D1(cyclin D1)的影响,探讨Art抗肝纤维化的分子机制。方法: 用血小板源性生长因子BB(platelet-derived growth factor BB, PDGF-BB)诱导HSC-T6细胞的增殖。实验分为对照组、PDGF-BB组、PDGF-BB+Art组(Art终浓度6.25 mg/L、25 mg/L、50 mg/L)和PDGF-BB+ERK抑制剂PD98059组。ELISA法测定细胞上清液中Ⅰ型胶原的含量,RT-PCR检测各组ERK1/2和cyclin D1 mRNA水平变化,Western blotting法检测各组p-ERK1/2和cyclin D1蛋白表达水平,凝胶电泳迁移率实验(EMSA)检测AP-1的活性。结果: (1)PDGF-BB 可明显促进HSC-T6细胞的增殖,PDGF-BB+Art各剂量组和PDGF-BB+PD98059均可抑制HSC-T6细胞上清液中Ⅰ型胶原的含量(P<0.05,P<0.01)。(2)PDGF-BB+Art组(50 mg/L)ERK1/2 mRNA的表达低于PDGF-BB组(P<0.05),其中PDGF-BB+PD98059组ERK1/2 mRNA的表达最低(P<0.01);PDGF-BB+Art组(25 mg/L、50 mg/L)和PDGF-BB+PD98059组cyclin D1 mRNA的表达明显低于PDGF-BB组(P<0.05,P<0.01)。(3)p-ERK1/2、cyclin D1蛋白表达水平在PDGF-BB组最高,而PDGF-BB+Art各剂量组和PDGF-BB+PD98059组降低(P<0.05,P<0.01)。(4)Art可使AP-1与DNA结合活性下降。结论: Art可抑制HSC-T6细胞增殖,其机制可能与其抑制ERK1/2蛋白活化从而降低AP-1的活性和下调cyclin D1的表达有关。     

15-HETE与ERK1/2在大鼠缺氧性肺动脉收缩中的作用

目的:为揭示缺氧性肺血管收缩机制,探讨细胞外信号调节激酶1/2 (ERK1/2)是否参与15-羟基二十碳四烯酸（15-HETE）收缩缺氧大鼠肺动脉的过程以及15-HETE对 ERK1/2活性的影响。 方法: 将大鼠置于氧气分数为12.0％的低氧箱中连续9 d形成缺氧模型。完整取出心肺，在显微镜下分离直径0.8-1.0 mm肺动脉剪为3 mm长的动脉环在组织浴槽内进行张力研究。比较15-HETE给药前后肺动脉环张力变化；用ERK1/2上游激酶抑制剂U0126孵育肺动脉环，比较U0126孵育前后15-HETE对缺氧性肺动脉环的收缩作用；机械法去除动脉环内皮，再比较U0126孵育前后15-HETE的收缩作用。酶法分离培养大鼠肺动脉平滑肌细胞。Western blotting方法检测15-HETE作用时间（5-90 min）及浓度（10^-9-10^-6 mol/L）对 ERK1/2 的表达及活性的影响。 结果: 15-HETE对缺氧大鼠肺动脉环有收缩作用，呈浓度-效应关系，与正常对照组比较差异显著（P<0.05）；内皮完整和内皮去除的肺动脉环，U0126孵育前后，15-HETE的缩血管作用都受到抑制，差异显著（均为P<0.05）。Western bloting结果显示，15-HETE明显增强肺动脉血管平滑肌细胞ERK1/2的活性，随时间延长而降低，随浓度增加而增加，但对ERK1/2的蛋白表达无影响。 结论:15-HETE能上调大鼠肺动脉血管平滑肌细胞ERK1/2的活性，提示ERK1/2的活化是15-HETE收缩慢性缺氧大鼠肺动脉的一个重要环节。     

细菌脂多糖通过MAPK / ERK1 / 2 信号通路影响成骨细胞活性和凋亡

目的:探讨细菌脂多糖(LPS)通过丝裂原活化蛋白激酶/细胞外调节蛋白激酶(MAPK/ERK1/2)信号通路对成骨细胞活性和凋亡的影响。方法:将小鼠前体成骨细胞MC3T3-E1随机分为对照组、LPS组、LPS+U0126组,对照组不给予LPS处理,LPS组给予10 mmol/L LPS处理,LPS+U0126组给予10 mmol/L LPS和25μmol/L ERK1/2激酶抑制剂U0126处理。采用噻唑蓝(MTT)测定细胞活性,采用流式细胞术测定细胞凋亡,采用硝基苯磷酸二钠基质动力学方法测定碱性磷酸酶(ALP),采用放射免疫法测定骨钙素(BGP)活性,采用Hochest 33258染色观察细胞核形态,采用Western blot测定活化型细胞半胱氨酸天冬氨酸特异性蛋白酶3型(C-Caspase 3)、Bcl-2相关X蛋白(Bax)、B淋巴细胞瘤-2基因(Bcl-2)、ERK1/2、磷酸化ERK1/2(p-ERK1/2)蛋白水平。结果:与对照组比较,LPS组和LPS+U0126组MC3T3-E1细胞活性、ALP和BGP活性降低(P0.05),细胞凋亡率升高(P0.05),C-Caspase 3、Bax、p-ERK1/2蛋白水平升高(P0.05),Bcl-2蛋白水平降低(P0.05);与LPS组比较,LPS+U0126组MC3T3-E1细胞活性、ALP和BGP活性升高(P0.05),细胞凋亡率降低(P0.05),C-Caspase 3、Bax、p-ERK1/2蛋白水平降低(P0.05),Bcl-2蛋白水平升高(P0.05)。对照组细胞核正常;LPS组细胞凋亡形态数量明显增多;LPS+U0126组凋亡形态细胞数量较LPS组减少。结论:LPS可通过抑制MAPK/ERK1/2信号通路抑制成骨细胞活性,诱导成骨细胞凋亡。     

ERK和Smad通路在TGF-β1抑制大鼠血管平滑肌细胞增殖中的作用

目的： 探讨ERK通路是否参与TGF-β/Smad 通路诱导的血管平滑肌细胞增殖及可能的分子机制。方法: 原代培养大鼠胸主动脉平滑肌细胞,细胞分4组：(1)对照组;(2)TGF-β1组;(3)ERK阻断剂(PD98059)组;(4)TGF-β1+ ERK阻断剂(PD98059)组。MTT法测细胞的增殖活性,Western blotting法检测VSMCs中细胞内核增殖抗原(PCNA)、Smad2/3、ERK1/2、Smad7蛋白表达及相关磷酸化蛋白含量,RT-PCR方法测VSMCs中Smad2、3、7mRNA的表达。结果: (1)各组PCNA蛋白表达和MTT法测得A值均低于对照组 (P＜0.05),TGF-β1+ ERK阻断剂组与TGF-β1组相比无显著差异。（2）与对照组相比,TGF-β1组p-Smad2/3、p-ERK1/2蛋白含量和Smad7蛋白表达增高 (P<0.05),ERK阻断剂组则明显降低(P<0.05);与TGF-β1组比,TGF-β1+ERK阻断剂组降低 (P<0.05)。各组间Smad2/3、ERK1/2蛋白表达无显著差异。(3)与对照组相比,TGF-β1组Smad7 mRNA表达增高 (P<0.05),ERK阻断剂组和TGF-β1+ERK阻断剂组降低(P<0.05);与TGF-β1组比,TGF-β1+ERK阻断剂组表达降低(P<0.05)。各组内VSMCs 的Smad2、Smad3 mRNA表达无显著差异。结论: (1)TGF-β1诱导的Smad2/3蛋白磷酸化依赖ERK通路激活,但对TGF-β1的抑制平滑肌细胞增殖的作用无影响,可能有其它信号通路参与此过程。(2)ERK通路可通过蛋白和mRNA水平促进Smad7表达,反过来其又可促进ERK通路激活。(3)ERK通路对Smad2/3蛋白和mRNA水平无影响。     

Rho-kinase activation is involved in hypoxia-induced pulmonary vasoconstriction.

Rho-associated serine/threonine kinase (Rho-kinase) is a downstream effector of small GTPase RhoA that has recently been shown to play an important role in regulating smooth muscle contraction. The present study investigated the role of Rho/ Rho-kinase in hypoxia-induced pulmonary vasoconstriction (HPV). Small pulmonary resistance vessels and cultured pulmonary arterial smooth muscle cells (PASMCs) from the rat were used. PASMCs exposed to hypoxia (PO(2) = 26 +/- 2 mm Hg) showed a significant increase in Rho-kinase activity. Exposure to hypoxia for 20, 40, 60, 90, and 120 min also resulted in a significant increase in myosin light chain (MLC) phosphorylation at all time points in PASMCs. Hypoxia-induced MLC phosphorylation was inhibited by Y-27632 (a Rho-kinase inhibitor), exoenzyme C3 (a specific Rho inhibitor), or toxin B (an inhibitor for Rho proteins). In addition, hypoxia-induced Rho-kinase activation was blocked by C3 and toxin B. Small rat intrapulmonary arterial rings, which were made hypoxic (PO(2) = 30 +/- 3 mm Hg), showed a slow sustained contraction, and Y-27632 caused a significant relaxation during the sustained phase of HPV in a concentration-dependent manner. In summary, the data show that Rho-kinase is activated by hypoxia in PASMCs, and Rho/Rho-kinase is functionally linked to hypoxia-induced MLC phosphorylation and plays a role in the sustained phase of HPV.     

NHE-1与大鼠肺动脉平滑肌细胞增殖和凋亡

目的:探讨Na⁺/H⁺交换器-1(NHE-1)、细胞内pH对肺动脉平滑肌细胞增殖和凋亡的作用。方法:实验分对照组和低氧3周组,大鼠常压低氧3周后,分离肺动脉平滑肌层,测定细胞内pH,并应用RT-PCR技术,检测NHE-1mRNA表达的变化。体外培养肺动脉平滑肌细胞,诱导细胞酸化后,原位细胞凋亡检测不同浓度及时间NHE-1特异性抑制剂作用后,细胞凋亡率的改变。结果:低氧组肺动脉平滑肌细胞内pH及NHE-1mRNA表达均明显高于正常对照组。随药物浓度增加和作用时间延长,细胞凋亡率明显增高。结论:NHE-1参与调节细胞内pH,在肺动脉平滑肌细胞增殖和凋亡中起重要的作用。     

RhoA/Rho激酶信号通路与肺动脉高压

目前研究已发现RhoA/Rho激酶信号通路参与了人体多种疾病的形成,如高血压、冠心病、脑率中等.肺动脉高压的病理学改变包括内皮细胞的损伤、增殖,肺血管平滑肌细胞的高反应性,炎症细胞迁移和黏附以及肺小血管形成和栓塞;Rho激酶调节细胞的多种生物学行为和功能,如收缩、黏附、迁移、增殖、凋亡、基因表达等.研究表明RhoA/R...     

RhoA调节失血性休克大鼠血管反应性的机制

目的： 探讨RhoA调节失血性休克大鼠血管反应性的机制。方法: 采用SD大鼠复制休克模型,取离体血管环,观察Rho激酶、肌球蛋白轻链磷酸酶（MLCP）、肌球蛋白轻链磷酸激酶（MLCK）对RhoA增加血管反应性的作用;同时取原代血管平滑肌细胞（VSMCs）,观察RhoA对缺氧后VSMC Rho激酶、MLCP和MLCK活性的调节作用以及对肌球蛋白轻链（MLC20）磷酸化水平的影响。结果: 失血性休克后大鼠肠系膜上动脉（SMA）对NE收缩反应性明显降低,RhoA的激动剂U-46619可明显升高休克后血管反应性,RhoA特异性抑制剂C3酶可拮抗U-46619所引起的血管收缩反应性的升高。Rho激酶抑制剂Y-27632可降低由U-46619所引起的血管反应性的升高,MLCP的抑制剂Calyculin可进一步增加由U-46619所引起的血管反应性的升高,而MLCK抑制剂对U-46619的作用影响不明显。缺氧后MLCK、Rho激酶活性以及MLC20磷酸化水平明显降低,MLCP活性明显升高,RhoA激动剂U-46619可明显升高缺氧后VSMC的MLC20磷酸化水平、Rho激酶活性和降低MLCP的活性,且U-46619的这一作用可被RhoA抑制剂C3酶所拮抗,调节RhoA的活性对MLCK活性无明显调节作用。结论: RhoA可通过Rho激酶调节MLCP活性和 MLC20磷酸化水平调节休克后血管反应性。     

Thromboxane a(2) induces differentiation of human mesenchymal stem cells to smooth muscle-like cells

Thromboxane A(2) (TxA(2)) is involved in smooth muscle contraction and atherosclerotic vascular diseases. Accumulating evidence suggests a pivotal role for mesenchymal stem cells (MSCs) in vascular remodeling. In the present study, we demonstrate for the first time that the TxA(2) mimetic U46619 induces differentiation of human adipose tissue-derived MSCs (hADSCs) to smooth muscle-like cells, as demonstrated by increased expression of smooth muscle-specific contractile proteins such as alpha-smooth muscle actin (alpha-SMA), calponin, smoothelin, and smooth muscle-myosin heavy chain. Using an in vitro collagen gel lattice contraction assay, we showed that U46619-induced expression of the contractile proteins was associated with increased contractility of the cells. U46619 increased the intracellular Ca(2+) concentration in hADSCs and pretreatment of the cells with the thromboxane receptor antagonist SQ29548 or the calmodulin (CaM) inhibitor W13 abrogated the U46619-induced alpha-SMA expression and contractility, suggesting a pivotal role of Ca(2+)/CaM in the U46619-stimulated smooth muscle differentiation of hADSCs. In addition, U46619 elicited activation of RhoA in hADSCs, and pretreatment of the cells with the Rho kinase-specific inhibitor Y27632 or overexpression of the dominant-negative mutants of RhoA and Rho kinase blocked U46619-stimulated alpha-SMA expression and contractility. Furthermore, U46619 induced phosphorylation of myosin light chain (MLC) through CaM/MLC kinase- and Rho kinase-dependent pathways, and the MLC kinase inhibitor ML-7 abrogated U46619-induced alpha-SMA expression and contractility. These results suggest that U46619 induces differentiation of hADSCs to contractile smooth muscle-like cells through CaM/MLCK- and RhoA-Rho kinase-dependent actin polymerization.     

BMP4 induces HO-1 via a Smad-independent, p38MAPK-dependent pathway in pulmonary artery myocytes

Bone morphogenetic proteins (BMPs) are multifunctional cytokines, which play a key role in vascular development and remodeling. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, has been shown to be protective against vascular and lung injury. In a microarray study, we identified HO-1 as a major target of BMP4 signaling in human pulmonary artery smooth muscle cells (PASMCs), and confirmed the induction of HO-1 mRNA and protein by RT-PCR and Western blotting, respectively. Immunoblotting demonstrated that incubation of PASMCs with BMP4 rapidly phosphorylated Smad1/5 and activated the mitogen-activated protein kinases, p38(MAPK) and ERK1/2, in PASMCs, but not JNK. Using pathway selective inhibitors, the induction of HO-1 mRNA and protein was shown to be dependent on activation of p38(MAPK). Induction was independent of Smad1/5 signaling, since HO-1 mRNA and protein induction was intact in PASMCs harboring mutations in the kinase domain of BMP type II receptor, with disrupted Smad signaling. In addition, adenoviral transfection of kinase-deficient BMPR-II also failed to inhibit BMP4-induced HO-1 expression. In functional studies, the HO-1 inhibitor, ZnPP-IX, partly reversed the growth-inhibitory effects of BMP4, and overexpression of HO-1 in PASMCs inhibited serum-stimulated [3H]-thymidine incorporation. Taken together, these findings show that HO-1 is an important Smad-independent target of BMP signaling in vascular smooth muscle. Inhibition of HO-1 function or expression will further increase the proproliferative capacity of BMPR-II-deficient PASMCs and may thus represent a potential "second hit" necessary for disease manifestation.     

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.     

VEGF和PCNA在慢性低氧性肺动脉及高压大鼠主动脉、肺动脉平滑肌细胞中表达

目的研究慢性低氧性肺动脉高压(PAH)发生过程中,血管内皮生长因子(VEGF)及细胞核增殖抗原(PCNA)在体循环血管、肺循环血管平滑肌细胞中的表达。方法利用低压缺氧舱建立大鼠缺氧性肺动脉高压模型。实验分为3组即正常氧组、缺氧2wk组和缺氧3wk组。用免疫组化染色和图像分析,检测主动脉、肺动脉主干及肺内小动脉平滑肌细胞中VEGF及PCNA的表达量。结果VEGF在正常氧组大鼠的主动脉、肺动脉主干及肺内小动脉平滑肌内均有表达;缺氧组大鼠肺动脉主干及肺内小动脉平滑肌细胞内VEGF的表达明显增强并随着缺氧时间的延长而增加;主动脉平滑肌内VEGF的表达量无明显变化。PCNA在正常氧组大鼠的主动脉、肺动脉主干及肺内小动脉平滑肌内均有微弱表达;但缺氧时只有肺小动脉平滑肌内其表达量增加;主动脉、肺动脉主干平滑肌内PCNA的表达量无明显差别。结论在缺氧性肺动脉高压的发生过程中,VEGF在体循环血管、肺循环血管平滑肌细胞中的表达量具有差异性,提示其可能在肺动脉高压形成过程中起重要作用。     

SOST expression is restricted to the great arteries during embryonic and neonatal cardiovascular development.

Spatial-temporal regulation of bone morphogenetic protein (BMP) and Wnt activity is essential for normal cardiovascular development, and altered activity of these growth factors causes maldevelopment of the cardiac outflow tract and great arteries. In the present study, we show that SOST, a Dan family member reported to antagonize BMP and Wnt activity, is expressed within the medial vessel wall of the great arteries containing smooth muscle cells. The ascending aorta, aortic arch, brachiocephalic artery, common carotids, and pulmonary trunk were all associated with SOST expressing smooth muscle cells, while the heart itself, including the valves, and more distal arteries, that is, pulmonary arteries, subclavian arteries, and descending aorta, were negative. SOST was expressed from embryonic day 15.5 up to the neonatal period. SOST expression, however, did not correspond with inhibition of Smad-dependent BMP activity or beta-catenin-dependent Wnt activity in the great arteries. Activity of both signaling pathways was already down-regulated before induction of SOST expression.