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1.
摘要 目的:研究顺铂联合血管内皮生长因子(vascular endothelial growth factor,VEGF)治疗对食管癌移植瘤小鼠免疫功能、癌细胞增殖以及肺转移的影响。方法:30只BALB/c小鼠通过皮下注射食管癌移植瘤模型。一周后,30只食管癌移植瘤模型小鼠被随机均分为3组,即模型组、顺铂组和联合组。模型组不进行治疗,顺铂组腹腔注顺铂治疗,联合组腹腔注射顺铂联合尾静脉注射VEGF抗体进行治疗,共治疗7周。比较各组小鼠体重,食管癌移植瘤体积和重量,卵巢癌细胞肺组织转移结节数、癌细胞转移面积和转移病灶总数,以及食管癌移植瘤外周血CD4+、CD8+以及CD4+/CD8+ T淋巴细胞比例。结果:(1)顺博组和联合组小鼠体重均显著高于对照组,而联合组小鼠体重显著高于顺铂组(P<0.05);(2)顺铂组和联合组小鼠CD4+和CD8+细胞比例均显著低于对照组(P<0.05),而CD4+/CD8+却显著高于对照组(P<0.05);(3)联合组小鼠CD4+和CD8+细胞比例均显著高于对照组(P<0.05),而CD4+/CD8+却显著低于顺铂组(P<0.05);(4)顺铂组和联合组小鼠食管癌肿瘤组织体积和重量,肺转移结节数、转移面积和转移病灶数均显著低于对照组(P<0.05),而联合组小鼠显著低于顺铂组(P<0.05)。结论:VEGF抗体可以显著增强顺铂在体内对食管癌的抗癌特性,并有助于增强食管癌移植瘤小鼠免疫功能、抑制癌细胞体内增殖和肺部转移。  相似文献   

2.
摘要 目的:探讨虫草素对慢性肾脏病(chronic kidney disease,CKD)大鼠血管内皮损伤的保护作用及其机制。方法:慢性肾脏病大鼠(n=48)随机平分为四组-模型组、虫草素高剂量组、虫草素中剂量组、虫草素低剂量组,虫草素高剂量组、虫草素中剂量组、虫草素低剂量组,分别给予虫草素160 mg/kg、80 mg/kg、40 mg/kg,模型组灌胃给予等量生理盐水,每天1次,连续给药治疗2周。结果:虫草素高剂量组、虫草素中剂量组、虫草素低剂量组治疗1周、治疗2周的24 h尿量、血清尿素氮(blood urea nitrogen,BUN)与肌酐(serum creatinine,Scr)水平都低于模型组(P<0.05),体重都高于模型组(P<0.05),不同剂量组别之间对比差异也有统计学意义(P<0.05)。虫草素高剂量组、虫草素中剂量组、虫草素低剂量组治疗2周的结缔组织生长因子(Connective tissue growth factor,CTGF)、血管内皮生长因子(Vascular endothelial growth factor,VEGF)蛋白相对表达水平高于模型组(P<0.05),肾小球硬化指数、肾小管损伤评分都低于模型组(P<0.05),不同剂量组别之间对比差异也有统计学意义(P<0.05)。结论:虫草素在慢性肾脏病大鼠的应用能发挥血管内皮损伤保护作用,促进改善大鼠的肾功能,提高大鼠的体重,且具有剂量依赖性。  相似文献   

3.
摘要 目的:探讨丹酚酸B(salvianolic acid B,Sal B)对肝癌荷瘤小鼠抑瘤作用及对肝纤维化的影响。方法:将HepG2肝癌细胞株皮下注射于裸鼠左腋下成瘤,将荷瘤小鼠(n=42)随机平分为三组:模型组、Sal B 1组与Sal B 2组。Sal B 1组与Sal B 2组于造模成功当天开始分别给予10 mL/kg/d和15 mL/kg/d丹酚酸B进行灌胃,模型组给予等量生理盐水灌胃,每周 2次,连续 4周。结果:治疗第2周与第4周后,Sal B 1组、Sal B 2组的移植瘤重量均低于模型组(P<0.05),抑瘤率高于模型组(P<0.05),Sal B 1组与Sal B 2组对比差异有统计学意义(P<0.05)。Sal B 1组、Sal B 2组肝脏系数与肝脏表面癌结节数目均低于模型组(P<0.05),Sal B 2组低于Sal B 1组(P<0.05)。Sal B 1组、Sal B 2组血清天门冬氨酸氨基转移酶(Aspartate transaminase,AST)、丙氨酸氨基转移酶(Alanine transaminase,ALT)含量均低于模型组(P<0.05),Sal B 2组低于Sal B 1组(P<0.05)。Sal B 1组、Sal B 2组肝组织转化生长因子-β1(Transforming growth factor-beta 1,TGF-β1)、Smad3蛋白相对表达水平均低于模型组(P<0.05),Sal B 2组低于Sal B 1组(P<0.05)。结论:Sal B在肝癌荷瘤小鼠中能发挥抑瘤作用,可抑制血清ALT与AST的释放,其可能是通过TGF-β1/Smad3信号发挥抗肝纤维化-肝癌作用。  相似文献   

4.
目的:探讨青蒿琥酯对肺癌细胞裸鼠皮下移植瘤生长和放射敏感性的影响。方法:将肺癌细胞接种至裸鼠皮下,腹腔注射青蒿琥酯,同时给予放射处理记为联合组,设置青蒿琥酯组(不照射处理)、放射组(腹腔注射生理盐水)和对照组(腹腔注射生理盐水,不放射处理),测量肿瘤体积,取瘤体并称取瘤体重量,脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)法检测组织中细胞凋亡水平,Western blot检测组织中活化的含半胱氨酸的天冬氨酸蛋白水解酶3(Cleaved Caspase-3)、信号转导与转录因子3(STAT3)、磷酸化的STAT3(p-STAT3)、p38丝裂原活化蛋白激酶(p38MAPK)、磷酸化的p38MAPK(p-p38MAPK)水平。结果:青蒿琥酯组、放射组、联合组皮下移植瘤体积和重量均明显低于对照组,联合组肿瘤重量和体积明显低于青蒿琥酯和放射组,差异均具有统计学意义(P0.05)。青蒿琥酯、放射组、联合组肿瘤组织中细胞凋亡率、Cleaved Caspase-3水平和p-p38MAPK/p38MAPK均明显高于对照组,联合组肿瘤组织中细胞凋亡率、Cleaved Caspase-3水平和p-p38MAPK/p38MAPK高于青蒿琥酯和放射组,差异均具有统计学意义(P0.05)。青蒿琥酯、放射组、联合组肿瘤组织中p-STAT3/STAT3水平明显低于对照组,联合组肿瘤组织中p-STAT3/STAT3水平低于蒿琥酯组和放射组,差异均具有统计学意义(P0.05)。结论:青蒿琥酯能够抑制肺癌细胞裸鼠皮下移植瘤生长,促进癌细胞凋亡,增加放疗敏感性,作用机制可能与p38MAPK、STAT3信号通路有关。  相似文献   

5.
摘要 目的:探讨藻蓝蛋白对非小细胞肺癌细胞移植瘤生长的抑制及促凋亡作用的机制研究。方法:4~6周龄30只无胸腺BALB/c裸鼠随机分为移植瘤组和藻蓝蛋白组。每5天用卡尺测量裸鼠肿瘤体积。通过RT-PCR检测裸鼠肿瘤中凋亡相关因子MMP-2、MMP-9、Bcl-2、Bax的mRNA表达。通过流式细胞术分析细胞周期。通过蛋白印迹分析EMT相关蛋白的表达。通过ELISA检测血浆细胞因子TNF-α、IL-6、IL-1β和TGF-β的浓度。通过蛋白印迹分析STAT3/NF-κB信号通路的表达。结果:第13天时,移植瘤组和蓝藻蛋白组肿瘤大小比较无差异(P>0.05),第18天和第25天时,藻蓝蛋白组肿瘤体积较移植瘤组减小(P<0.05)。藻蓝蛋白组MMP-2、MMP-9和Bcl-2的mRNA表达较移植瘤组降低(P<0.05),藻蓝蛋白组Bax mRNA表达较移植瘤组升高(P<0.05)。藻蓝蛋白组G1期占比较移植瘤组升高(P<0.05),藻蓝蛋白组G1期占比较移植瘤组升高(P<0.05),藻蓝蛋白组S期和G2期占比较移植瘤组降低(P<0.05)。藻蓝蛋白组N-钙粘蛋白和VEGF蛋白表达较移植瘤组降低(P<0.05),藻蓝蛋白组E-钙粘蛋白表达较移植瘤组升高(P<0.05)。藻蓝蛋白组TNF-α、IL-6、IL-1β和TGF-β的浓度较移植瘤组降低(P<0.05)。藻蓝蛋白组p-STAT3、p-IκBα和p-NF-κB p65蛋白表达较移植瘤组降低(P<0.05)。结论:藻蓝蛋白通过调控STAT3/ NF-κB信号通路抑制炎性细胞因子的分泌和EMT发生,促进肿瘤细胞凋亡,抑制裸鼠体内移植瘤的生长。  相似文献   

6.
摘要 目的:探讨与研究咖啡酸对食管鳞状细胞癌KYSE450裸鼠移植瘤生长的影响及分子机制。方法:将食管鳞状细胞癌移植瘤裸鼠(n=48)随机平分为三组-模型组、5-氟尿嘧啶组与咖啡酸组。三组分别经腹腔注射0.2 mL生理盐水、5-氟尿嘧啶25 g/kg、5-氟尿嘧啶25 g/kg与咖啡酸50 mg/kg,2次/周,持续4周。结果:5-氟尿嘧啶组与咖啡酸组治疗第2周与第4周的体重高于模型组(P<0.05),咖啡酸组高于5-氟尿嘧啶组(P<0.05)。5-氟尿嘧啶组与咖啡酸组治疗第2周与第4周的肿瘤体积少于模型组(P<0.05),咖啡酸组高于5-氟尿嘧啶组(P<0.05)。5-氟尿嘧啶组与咖啡酸组治疗第4周的血清TNF-α与IL-6含量低于模型组(P<0.05),咖啡酸组低于5-氟尿嘧啶组(P<0.05)。5-氟尿嘧啶组与咖啡酸组治疗第4周的移植瘤Bax、Caspase-3蛋白相对表达水平与凋亡指数高于模型组(P<0.05),咖啡酸组高于5-氟尿嘧啶组(P<0.05)。结论:咖啡酸在食管鳞状细胞癌裸鼠的应用能与5-氟尿嘧啶发挥协同作用,能通过上调Bax、Caspase-3蛋白的表达,促进移植瘤细胞凋亡,抑制炎症因子的表达,减少血管总数,从而抑制移植瘤生长,促进恢复裸鼠体重。  相似文献   

7.
摘要 目的:探讨康柏西普在糖尿病大鼠早期视网膜病变中的作用及对血管内皮生长因子 (vascular endothelial growth factor,VEGF)和细胞间粘附分子-1(Intercellular adhesion molecule-1,ICAM-1)及C-反应蛋白(C-reactive protein,CRP)的影响。方法:糖尿病大鼠早期视网膜病变模型(n=27)随机平分为三组-模型组、替米沙坦组与康柏西普组,造模成功后当天三组分别给予注射生理盐水、替米沙坦、康柏西普治疗,1次/w,持续4 w,检测VEGF、ICAM-1及CRP表达情况。结果:大鼠造模成功后均出现食欲增多、饮水、尿量、体重减轻的现象。替米沙坦组与康柏西普组治疗第1 w与第4 w的体重高于模型组(P<0.05),康柏西普组高于替米沙坦组(P<0.05)。替米沙坦组与康柏西普组治疗第1 w与第4 w的空腹血糖低于模型组(P<0.05),康柏西普组低于替米沙坦组(P<0.05)。替米沙坦组与康柏西普组治疗第4 w的视网膜VEGF、ICAM-1、CRP蛋白相对表达水平低于模型组(P<0.05),康柏西普组低于替米沙坦组(P<0.05)。康柏西普组视网膜厚度变薄不明显,内、外核层细胞排列整齐,神经纤维层未见明显空泡样变性。结论:康柏西普在糖尿病大鼠早期视网膜病变中的应用能抑制VEGF、ICAM-1及CRP的表达,能促进降低血糖,增加大鼠体重。  相似文献   

8.
摘要 目的:探讨与研究噻托溴铵辅助治疗呼吸窘迫综合征对血清一氧化氮(Nitric oxide,NO)与血管内皮生长因子(vascular endothelial growth factor,VEGF)水平的影响。方法:2016年9月到2020年9月选择在本院进行急诊的呼吸窘迫综合征患者84例,根据随机数字表法把患者分为噻托溴铵组与对照组各42例。对照组给予鼻塞式持续气道正压通气治疗,噻托溴铵组在对照组治疗的基础上给予噻托溴铵治疗,两组都治疗观察2 w,检测血清NO与VEGF表达变化情况。结果:治疗后噻托溴铵组的总有效率为97.6 %,高于对照组的85.7 % (P<0.05)。两组治疗后的氧合指数高于治疗前(P<0.05),噻托溴铵组高于对照组(P<0.05)。两组治疗后的FEV1与FVC值高于治疗前(P<0.05),噻托溴铵组高于对照组(P<0.05)。两组治疗后的血清NO值高于治疗前(P<0.05),血清VEGF值低于治疗前(P<0.05),噻托溴铵组与对照组对比差异也都有统计学意义(P<0.05)。结论:噻托溴铵辅助治疗呼吸窘迫综合征能抑制血清VEGF的表达与促进NO的释放,改善患者的肺功能与氧合状况,从而提高治疗效果。  相似文献   

9.
目的探讨人表皮生长因子显性负性突变体(dominant negative epidermal growth factor receptor,DNEGFR))对胃癌细胞促血管形成能力的影响及其分子机制,并检测其对裸鼠皮下移植瘤生长的影响。方法选用2株人胃癌细胞,分为如下6组:SGC-7901及NCI-N87细胞未转染组(US组,UN组),SGC-7901及NCI-N87细胞pEGFP-N1质粒转染组(ES组,EN组),SGC-7901及NCI-N87细胞pEGFPN1-DNEGFR质粒转染组(DS组,DN组)。采用人脐静脉内皮细胞(humanumbilical vein endothelial cell,HUVEC)管腔结构形成实验检测体外促血管形成能力,采用酶联免疫吸附测定法(enzyme-linked immunosorbent assay,ELISA)测定细胞培养液中血管内皮生长因子(vascular endothelial growth factor,VEGF)的水平,建立人胃癌细胞裸鼠移植瘤模型,标本微血管密度(microvessel density,MVD)检测体内促血管形成能力,标本体积检测其对裸鼠皮下移植瘤生长的影响。结果转染pEGFPN1-DNEGFR质粒的人胃癌细胞株出现HUVEC管腔结构形成抑制,培养液中VEGF水平降低,MVD计数降低,裸鼠皮下移植瘤体积变小。结论 DNEGFR可能通过下调VEGF分泌抑制胃癌细胞体外及裸鼠体内促血管形成能力,最终抑制裸鼠皮下移植瘤生长。  相似文献   

10.
摘要 目的:探讨视网膜病变早产儿视网膜厚度与血清血管内皮生长因子(vascular endothelial growth factor,VEGF)、色素上皮衍生因子(pigment epithelium derived factor,PEDF)表达的相关性。方法:采用回顾性研究方法,2016年2月到2021年6月选择在新疆维吾尔自治区人民医院眼科就诊的早产儿视网膜病变患儿80例作为观察组,同期选择足月视网膜病变患儿80例作为对照组,测定两组患儿视网膜厚度,检测血管新生细胞因子-PEDF与VEGF表达情况,对两者进行相关性分析。结果:观察组患儿的颞侧、上方、下方的视网膜神经纤维层厚度都显著高于对照组,两组对比差异明显(P<0.05)。观察组患儿的血清VEGF水平高于对照组,PEDF水平低于对照组,对比差异有统计学意义(P<0.05)。在观察组患儿中,Pearson相关系数相关性分析显示血清PEDF水平与VEGF水平呈现显著负相关性(r=-0.341, P<0.05);患儿颞侧、上方、下方的视网膜神经纤维层厚度与血清PEDF水平成显著负相关性(P<0.05),与血清VEGF水平成显著正相关性(P<0.05)。多元logistic回归分析显示血清PEDF、VEGF水平都为导致早产儿视网膜厚度发生的重要因素(P<0.05)。结论:早产儿视网膜厚度均高于足月儿,血管新生细胞因子PEDF、VEGF呈现异常表达情况,视网膜厚度与PEDF、VEGF的表达都有一定的相关性,PEDF、VEGF也为导致早产儿视网膜病变发生的重要因素。  相似文献   

11.
Model analysis of difference between EGF pathway and FGF pathway   总被引:4,自引:0,他引:4  
The difference in time course of Ras and mitogen activated protein kinase (MAPK) cascade by different growth factors is considered to be the cause of different cellular responses. We have developed the computer simulation of Ras-MAPK signal transduction pathway containing newly identified negative feedback system, Sprouty, and adaptor molecules. Unexpectedly, negative feedback system did not profoundly affect time course of MAPK activation. We propose the key role of fibroblast growth factor receptor substrate 2 (FRS2) in NGF/FGF pathway for sustained MAPK activation. More Grb2-SOS complexes were recruited to the plasma membrane by binding to membrane-bound FRS2 in FGF pathway than in EGF pathway and caused sustained activation of ERK. The EGF pathway with high concentration of EGF receptor also induced sustained MAPK activation, which is consistent with the results in the PC12 cell overexpressing the EGF receptors. The simulated time courses of FRS2 knock-out cells were consistent with those of the reported experimental results.  相似文献   

12.
力生长因子(mechano growth factor,MGF)是新近发现的一种生长因子,由Igf-1基因剪接变异产生,拉伸刺激会促使成骨细胞表达力生长因子.比较分析了MGF及其羧基端E肽(MGF-Ct24E)对成骨细胞前体细胞MC3T3-E1分化的影响.结果显示:MGF和MGF-Ct24E具有显著激活胞外信号调节激酶1/2(Erk1/2)的作用,并降低了成骨细胞碱性磷酸酶、Ⅰ型胶原的表达,促进了骨桥蛋白(OPN)的表达,减少了核心绑定因子(corebinding factor1,Cbfα-1)的核转运量,对成骨细胞的分化具有延迟效应,这种效应通过抑制剂PD98059抑制Erk1/2的活化得到逆转;MGF还能显著激活磷脂酰肌醇3-激酶信号通路中的蛋白激酶B(Akt),该活化作用对成骨细胞分化是必需的,钙沉积分析显示长期培养下的细胞MGF促进了矿化节结的形成.这些结果说明,MGF-Ct24E对成骨细胞的分化具有抑制作用,这种作用与Erk1/2的活化有关,MGF因为包含E肽和IGF-1部分,能分别激活Erk1/2和Akt,因此对成骨细胞分化表现出双重效用,在成骨细胞分化早期,具有一定的延迟效应,而在分化晚期对成骨...  相似文献   

13.
14.
Summary Stromal-epithelial interactions are pivotal in many aspects of prostatic biology. A defined culture system is critical for the investigation of factors that regulate the growth and differentiation of human prostatic stromal cells. We have identified conditions which promote stromal cell attachment and proliferation in serum-free medium. MCDB 201, originally developed for the clonal growth of chick embryo fibroblasts, proved to be a superior basal medium of those that we tested. Supplementation of MCDB 201 with basic fibroblast growth factor (FGF), insulin-like growth factor (IGF), and platelet-derived growth factor (PDGF) permitted attachment and exponential growth of cells throughout a 7-d period with an initial inoculum as low as 103 cells per well of a 96-well microtiter dish. Using these assay conditions, we subsequently verified that basic FGF and IGF, but not PDGF, were required for optimal growth. No activity was found for heparin, transferrin, or the androgen R1881. Epidermal growth factor (EGF) didn’t stimulate growth when added to medium containing basic FGF and IGF, but was moderately stimulatory when added to basal medium alone. Cholera toxin inhibited growth. This simple and efficient culture medium provides a suitable assay system for more extensive studies of growth regulation and differentiation of human prostatic stromal cells, and will provide the basis for future development of a defined medium that supports clonal growth. Characterization of stromal-epithelial interactions will be facilitated by the use of this defined culture system for stromal cells in conjunction with the serum-free culture systems previously developed for human prostatic epithelial cells.  相似文献   

15.
Endocytic downregulation is a pivotal mechanism turning off signalling from the EGF receptor (EGFR). It is well established that whereas EGF binding leads to lysosomal degradation of EGFR, transforming growth factor (TGF)-α causes receptor recycling. TGF-α therefore leads to continuous signalling and is a more potent mitogen than EGF. In addition to EGF and TGF-α, five EGFR ligands have been identified. Although many of these ligands are upregulated in cancers, very little is known about their effect on EGFR trafficking.
We have compared the effect of six different ligands on endocytic trafficking of EGFR. We find that, whereas they all stimulate receptor internalization, they have very diverse effects on endocytic sorting. Heparin-binding EGF-like growth factor and Betacellulin target all EGFRs for lysosomal degradation. In contrast, TGF-α and epiregulin lead to complete receptor recycling. EGF leads to lysosomal degradation of the majority but not all EGFRs. Amphiregulin does not target EGFR for lysosomal degradation but causes fast as well as slow EGFR recycling. The Cbl ubiquitin ligases, especially c-Cbl, are responsible for EGFR ubiquitination after stimulation with all ligands, and persistent EGFR phosphorylation and ubiquitination largely correlate with receptor degradation.  相似文献   

16.
PC12 cells possess specific receptors for both nerve growth factor and epidermal growth factor, and by an unknown mechanism, nerve growth factor is able to attenuate the propagation of a mitogenic response to epidermal growth factor. The differentiation response of PC12 cells to nerve growth factor, therefore, predominates over the proliferative response to epidermal growth factor. We have observed that the addition of nerve growth factor to PC12 cells rapidly produces a decrease in surface 125I-epidermal growth factor binding capacity. Unlike previously described nerve growth factor effects on 125I-epidermal growth factor binding capacity, which required several days of nerve growth factor exposure, the decreases we report occur within minutes of nerve growth factor addition: A 50% decrease in 125I-epidermal growth factor binding capacity is evident at 10 min. This rapid nerve growth factor response is concentration dependent; inhibition of 125I-epidermal growth factor binding is detectable at nerve growth factor levels as low as 0.2 ng/ml and is maximal at approximately 50 ng/ml, consistent with known ranges of biological activity. No demonstrable differences in the rate of epidermal growth factor receptor synthesis or degradation were observed in cells acutely exposed to nerve growth factor. Scatchard analysis revealed that acute nerve growth factor treatment decreased the number of both high- and low-affinity 125I-epidermal growth factor binding sites, while the receptor affinity remained unchanged. We have also investigated the involvement of various potential intracellular mediators of nerve growth factor action and of known intracellular modulatory systems of the epidermal growth factor receptor for their capacity to participate in this nerve growth factor activity.  相似文献   

17.
The nerve growth factor: Thirty-five years later   总被引:15,自引:0,他引:15  
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18.
目的:研究碱性成纤维细胞生长因子(basic Fibroblast growth factor,bFGF)对热射病大鼠模型ET21、VWF、VEGF水平的影响。方法:选择SD大鼠36只随机分为6组,每组个6只,建立热射病大鼠模型后分为模型组、常温组、常温bFGF组、降温组、降温bFGF组,建模后0 h、2 h,比较不同级别生命征、血管功能因子。结果:建模后0 h,模型组Tr、HR、RR、MAP明显高于空白组(P0.05);建模后2 h,常温bFGF组、降温bFGF组明显低于常温组、降温组,降温组、降温bFGF组明显低于常温组、常温bFGF组(P0.05)。建模后0 h,模型组ET21、VWF的含量均明显高于空白组,VEGF含量明显低于热空白组(P0.05);建模后2 h,常温组ET21、VWF明显升高,VEGF明显降低,常温bFGF组、降温组、降温bFGF组ET21、VWF明显降低,VEGF明显升高(P0.05);降温组、降温bFGF组ET21、VWF明显低于常温组、常温bFGF组,VEGF明显高于常温组、常温bFGF组(P0.05);常温bFGF组、降温bFGF组ET21、VWF明显低于常温组与降温组,VEGF明显高于常温组与降温组(P0.05)。结论:碱性成纤维细胞生长因子有助于改善热射病大鼠生命体征,调节血管功能因子含量,提高热射病大鼠预后。  相似文献   

19.
The influence of islet-activating protein (IAP), a Bordetella pertussis toxin, was studied on adenylate cyclase and GTPase activities in rat adipocyte membranes. Pretreatment of rats or intact rat adipocytes with IAP did not affect adenylate cyclase inhibition by the stable GTP analog, GTP gamma S, whereas inhibition by GTP was abolished. Concomitantly, activation of the adipocyte enzyme by sodium and its inhibition by nicotinic acid were prevented. Furthermore, IAP treatment of adipocyte membranes prevented nicotinic acid-induced stimulation of a high affinity GTPase. The data suggest that a GTP-hydrolyzing system involved in the inhibitory regulation of adenylate cyclase is the target of IAP's action.  相似文献   

20.
Nerve growth factor-stimulated mitogen-activated protein kinase (pp42/44MAP) kinase was characterized by sequential column chromatography on DEAE-Sephacel, phenyl-Sepharose CL4B, and S-200. The kinase displayed an apparent molecular mass of 42 kDa and reacted with an antiphosphotyrosine antibody. Peptide mapping of myelin basic protein revealed the presence of one phosphopeptide that was phosphorylated on Thr-97. pp42/44MAP kinase activity was dependent on Mg2+ and inhibited by K252a both in vitro and in vivo. Nerve growth factor-stimulated kinase activation was diminished by down-regulation of protein kinase C with 200 nM 12-phorbol 13-myristate acetate or with staurosporine (1 nM), a protein kinase C inhibitor. Genistein, a protein tyrosine kinase inhibitor, blocked nerve growth factor-mediated neurite extension as well as diminished activation of pp42/44MAP kinase. Our data demonstrate that activation of this kinase system by nerve growth factor displays a requirement for both protein kinase C as well as protein tyrosine kinase. In addition, other agents that are capable of promoting neurite outgrowth in PC12 cells, such as fibroblast growth factor or dibutyryl cyclic AMP, do so independently of activating this kinase system.  相似文献   

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