MAPK家族与糖尿病并发症

丝裂原活化蛋白激酶（MAPK）是细胞促增殖和传递应激信号的关键激酶,该家族包括EPK、JNK、p38等亚族。最近的研究显示,糖尿病状态下的高糖－蛋白激酶C（PKC）通路、糖基化终产物、氧化应激、生长因子、渗透压、牵张刺激等都可激活MAPK家族,使转录因子活性升高,参与糖尿病慢性并发症的发生。阻断MAPK通路将可能成为糖尿病慢性并发症治疗的新方向。     

丝裂素活化蛋白激酶与1型糖尿病

丝裂素活化蛋白激酶（MAPK）参与了胰岛β细胞凋亡，很多细胞因子及应激刺激可激活MAPK信号转导通路，诱导胰岛β细胞凋亡。MAPK也可通过降低胰岛素样生长因子（IGF）水平而诱导胰岛β细胞凋亡，导致1型糖尿病的发生。探索MAPK信号转导通路在1型糖尿病发病中的作用，为预防1型糖尿病的发生提供新的理论基础。     

高糖对人肾小球系膜细胞p38MAPK／CREB通路与纤维化的影响

目的探讨高糖环境下人肾小球系膜细胞中p38丝裂原活化蛋白激酶／cAMP反应元件结合蛋白（p38MAPK／CREB）通路的活性及细胞外基质成分纤维黏连蛋白（FN）的变化。方法以5．6mmol／L葡萄糖培养基培养肾小球系膜细胞为对照组,观察高糖（30mmol／L）培养12、24、48小时。肾小球系膜细胞p38MAPK／CREB活性和FNmRNA、FN的变化。结果与对照组比较,高糖组各时间p-p38MAPK、P—CREB的表达均上升,并随着时间的延长,其表达逐渐升高;FN的表达升高,并且随着时间的延长,其表达进一步升高。结论高糖环境下p38MAPK／CREB通路被激活,FN表达增加,p38MAPK／CREB通路参与了细胞外基质重构的过程。     

p38丝裂原活化蛋白激酶在心血管疾病中的作用

丝裂原活化蛋白激酶（mitogen activated protein kinase，MAPKs）是细胞内的主要信息传递系统，可将细胞外信息传递至细胞核中，从而介导细胞产生各种反应。MAPK通路主要有4条途径：细胞外调节蛋白激酶（Ras／ERK）、c-jun氨基末端激酶（JNK）／应激激活的蛋白激酶（SAPK）、p38、ERK5，其中p38信号途径是MAPK家族中的重要组成部分，参与了多种细胞的胞内信号传递，现将在许多疾病的发生、发展过程中具有明显的调控作用。p38MAPK在心血管疾病中的作用论述如下。     

MAPK信号转导途径与糖尿病肾病

糖尿病状态下,多种因素激活丝裂原活化蛋白激酶(MAPK)信号转导通路。MAPK激活后,使肾脏细胞肥大,细胞外基质积聚,最终导致肾小球硬化和肾小管间质纤维化。应用MAPK阻断剂可以有效对抗上述作用,为临床上有效治疗糖尿病肾病提供一条新的思路。     

MAPK／ERK1／2信号转导途径与记忆关系

MAPK／ERK1／2（mitogen—activated protein kinase）信号转导途径是一条可被多种细胞外刺激因素广泛激活的有丝分裂原活化蛋白激酶通路,介导了细胞的增殖、分化和死亡多种病理生理过程。是一条关键的细胞信号转导途径,还和认知学习记忆密切相关,本文综述了MAPK／ERK1／2信号转导途径与学习、记忆的关系。     

MAPK家族与糖尿病并发症

丝裂原活化蛋白激酶 (MAPK)是细胞促增殖和传递应激信号的关键激酶 ,该家族包括ERK、JNK、p38等亚族。最近的研究显示 ,糖尿病状态下的高糖 蛋白激酶C(PKC)通路、糖基化终产物、氧化应激、生长因子、渗透压、牵张刺激等都可激活MAPK家族 ,使转录因子活性升高 ,参与糖尿病慢性并发症的发生。阻断MAPK通路将可能成为糖尿病慢性并发症治疗的新方向。     

胰腺纤维化相关转录因子及信号通路的研究进展

胰腺纤维化是慢性胰腺炎的重要特征,活化的胰腺星状细胞在胰腺纤维化的发生、发展过程中起着关键作用。核因子-κB、Smad、过氧化物酶体增殖物激活受体γ（PPARγ）、活化蛋白-1（AP-1）、信号转导及转录激活因子（STAT）等转录因子在胰腺纤维化过程中发挥重要作用,涉及多个重要的信号通路,包括转化生长因子-β（TGF-β）／Smad、丝裂原活化蛋白激酶（MAPK）、PI3激酶（PI3K）／Akt通路、Wnt／β-catenin、酪氨酸激酶-信号转导与转录激活因子（JAK-STAT）、活性氧（ROS）等。现就胰腺纤维化相关转录因子及信号通路的研究进展作一综述。     

丝裂素活化蛋白激酶与1型糖尿病

丝裂素活化蛋白激酶 (MAPK)参与了胰岛 β细胞凋亡 ,很多细胞因子及应激刺激可激活MAPK信号转导通路 ,诱导胰岛β细胞凋亡。MAPK也可通过降低胰岛素样生长因子 (IGF)水平而诱导胰岛β细胞凋亡 ,导致 1型糖尿病的发生。探索MAPK信号转导通路在 1型糖尿病发病中的作用 ,为预防 1型糖尿病的发生提供新的理论基础     

ERK1/2信号转导通路在宫颈癌发病中的作用

细胞外信号调节激酶（ERK）是丝裂原活化蛋白激酶（MAPK）家族成员之一,该酶被激活后,在细胞生长、发育、分裂、死亡及恶性转化等过程中发挥作用。由E RK1/2介导的信号转导通路接受来自细胞内外的各种丝裂原刺激和应激,激活ERK1/2底物,调控细胞增殖、凋亡与侵袭。为了揭示宫颈癌发生发展的分子学机制，探讨宫颈癌的有效防治方法，研究者从ERK1／2信号转导通路途径对宫颈癌做了大量研究。     

阿霉素诱导PI3'K/Akt/FKHRL1通路激活与胃癌细胞化疗耐药性的关系

目的 探讨阿霉素诱导胃癌细胞磷脂酰肌醇3’-激酶（PI3’K）／Akt／FKHRL1通路的激活对胃癌细胞SGC-7901化疗效果的影响及二者的关系。方法 阿霉素及PI3’K／Akt抑制剂Wortmannin分别作用于胃癌细胞SGC-7901，MTT比色法检测胃癌细胞的生存率，Western印迹法检测FKHRL1磷酸化表达水平。结果 阿霉素抑制胃癌细胞SGC-7901的生长，呈时间依赖性诱导FKHRL1磷酸化。Wortmannin可明显增强阿霉索的细胞生长抑制作用，同时下调阿霉素诱导的磷酸化FKHRL1表达。结论 阿霉素可能通过激活SGC-7901细胞的PI3’K／Akt通路诱导FKHRL1磷酸化，从而影响胃癌细胞的化疗耐药性。Wortmannin可以阻断PI3’K／Akt／FKHRL1通路而提高胃癌的化疗敏感性。     

病毒性肝炎患者CK,CK—MB及CK—MB／CK总活力百分比的研究

对107例病毒性肝炎(以下简称肝炎)患者血清CK、CK-MB水平及CK-MB/CK总活力百分比进行了检测,并与正常人对照,发现肝炎患者血清CK总活力平均水平比正常人明显下降(P<0.001);CK-MB均值与正常人无显著差异.对临床不同型别肝炎及不同程度黄疸分组作进一步研究发现,各组CK总活力水平无显著差异(P>0.05),但CK-MB/CK总活力百分比有显著差异(P<0.01),它们是:慢重肝>肝硬化失代偿>慢活肝>急性肝炎>慢迁肝;高黄疸>低黄疸>无黄疸;这一比值随肝损害程度加重而呈进行性上升,可能反映了肝炎并发心脏的损害。     

肺癌中PI3K／AKT信号通路对Skp2调控机制的研究

目的探讨肺癌中磷脂酰肌醇-3-激酶（P13K）／AKT信号通路对S期激酶相关蛋白2（Skp2）的调控机制。方法体外培养4种类型肺癌细胞系H460、LK2、H446和A549,经LY294002处理细胞24h后实时RT—PCR法检测Skp2基因表达变化;Westernblot检测E2F1蛋白表达变化。结果实时RT—PCR显示LY294002作用后4种肺肿瘤细胞系中skp2基因表达均下降;Westernblot结果表明在小细胞肺癌、肺鳞癌、大细胞肺癌中E2F1蛋白表达降低,肺腺癌中E2F1蛋白未表达。结论肺癌中P13K／AKT通路可在转录水平调节Skp2表达,在小细胞肺癌、肺鳞癌、大细胞肺癌中此种调节可能通过转录因子E2F1发挥作用,而肺腺癌中E2F1不参与此种调节。     

Structures of a platelet-derived growth factor/propeptide complex and a platelet-derived growth factor/receptor complex

Platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) are prototypic growth factors and receptor tyrosine kinases which have critical functions in development. We show that PDGFs share a conserved region in their prodomain sequences which can remain noncovalently associated with the mature cystine-knot growth factor domain after processing. The structure of the PDGF-A/propeptide complex reveals this conserved, hydrophobic association mode. We also present the structure of the complex between PDGF-B and the first three Ig domains of PDGFRβ, showing that two PDGF-B protomers clamp PDGFRβ at their dimerization seam. The PDGF-B:PDGFRβ interface is predominantly hydrophobic, and PDGFRs and the PDGF propeptides occupy overlapping positions on mature PDGFs, rationalizing the need of propeptides by PDGFs to cover functionally important hydrophobic surfaces during secretion. A large-scale structural organization and rearrangement is observed for PDGF-B upon receptor binding, in which the PDGF-B L1 loop, disordered in the structure of the free form, adopts a highly specific conformation to form hydrophobic interactions with the third Ig domain of PDGFRβ. Calorimetric data also shows that the membrane-proximal homotypic PDGFRα interaction, albeit required for activation, contributes negatively to ligand binding. The structural and biochemical data together offer insights into PDGF-PDGFR signaling, as well as strategies for PDGF-antagonism.     

Haematopoietic progenitor cells utilise conventional PKC to suppress PKB/Akt activity in response to c-Kit stimulation

Receptor tyrosine kinase (RTK) c-Kit signalling is crucial for the proliferation, survival and differentiation of haematopoietic stem cells (HSCs). To further understand the mechanisms underlying these events we explored how the downstream mediators interact. The present study investigated the function of conventional protein kinase Cs (c-PKC) in c-Kit mediated signalling pathways in HSC-like cell lines. This analysis supported earlier findings, that steel factor (SF) activates c-PKC, extracellular signal-regulated kinase (Erk) and protein kinase B (PKB). The present results were consistent with an important role of c-PKC in the positive activation of Erk and for proliferation. Further, it was observed that c-PKC negatively regulated PKB activity upon SF stimulation, indicating that c-PKC acts as a suppressor of c-Kit signalling. Finally, these observations were extended to show that c-PKC mediated the phosphorylation of the endogenous c-Kit receptor on serine 746, resulting in decreased overall tyrosine phosphorylation of c-Kit upon SF stimulation. This report showed that this specific feedback mechanism of c-PKC mediated phosphorylation of the c-Kit receptor has consequences for both proliferation and survival of HSC-like cell lines.     

C-peptide stimulates ERK1/2 and JNK MAP kinases via activation of protein kinase C in human renal tubular cells

Aims/hypothesis Accumulating evidence indicates that replacement of C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, but the molecular mechanisms involved are incompletely understood. C-peptide shows specific binding to a G-protein-coupled membrane binding site, resulting in Ca²⁺ influx, activation of mitogen-activated protein kinase signalling pathways, and stimulation of Na⁺, K⁺-ATPase and endothelial nitric oxide synthase. This study examines the intracellular signalling pathways activated by C-peptide in human renal tubular cells.Methods Human renal tubular cells were cultured from the outer cortex of renal tissue obtained from patients undergoing elective nephrectomy. Extracellular-signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and Akt/protein kinase B (PKB) activation was determined using phospho-specific antibodies. Protein kinase C (PKC) and RhoA activation was determined by measuring their translocation to the cell membrane fraction using isoform-specific antibodies.Results Human C-peptide increases phosphorylation of ERK1/2 and Akt/PKB in a concentration- and time-dependent manner in renal tubular cells. The C-terminal pentapeptide of C-peptide is equipotent with the full-length C-peptide, whereas scrambled C-peptide has no effect. C-peptide stimulation also results in phosphorylation of JNK, but not of p38 mitogen-activated protein kinase. MEK1/2 inhibitor PD98059 blocks the C-peptide effect on ERK1/2 phosphorylation. C-peptide causes specific translocation of PKC isoforms and to the membrane fraction in tubular cells. All stimulatory effects of C-peptide were abolished by pertussis toxin. The isoform-specific PKC- inhibitor rottlerin and the broad-spectrum PKC inhibitor GF109203X both abolish the C-peptide effect on ERK1/2 phosphorylation. C-peptide stimulation also causes translocation of the small GTPase RhoA from the cytosol to the cell membrane. Inhibition of phospholipase C abolished the stimulatory effect of C-peptide on phosphorylation of ERK1/2, JNK and PKC-.Conclusions/interpretation C-peptide signal transduction in human renal tubular cells involves the activation of phospholipase C and PKC- and PKC-, as well as RhoA, followed by phosphorylation of ERK1/2 and JNK, and a parallel activation of Akt.     

阿托伐他汀对同型半胱氨酸诱导的心肌细胞MEK/ERK通路及心肌线粒体损伤的影响

目的探讨阿托伐他汀对同型半胱氨酸(Hcy)诱导的心肌细胞H9c2丝裂原细胞外信号调节激酶(MEK)/细胞外调节蛋白激酶(ERK)通路及心肌线粒体损伤的影响。方法细胞计数试剂盒8(CCK-8)检测不同浓度Hcy对H9c2细胞存活率的影响,筛选Hcy诱导浓度和时间。将诱导后的H9c2细胞分为模型组、5μmol/L阿托伐他汀组、10μmol/L阿托伐他汀组和15μmol/L阿托伐他汀组,另取正常H9c2细胞为对照组。流式细胞仪检测各组细胞凋亡率;JC-1法检测各组细胞线粒体膜电位的变化;DCFH-DA法检测各组细胞内活性氧(ROS)水平;酶联免疫吸附法(ELISA)检测各组细胞中丙二醛(MDA)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)含量;Western blot检测各组细胞MEK1/2和ERK1/2磷酸化水平。结果与对照组相比,2μmol/L Hcy可显著降低H9c2细胞存活率(P0.05),本研究使用2μmol/L Hcy处理24 h诱导H9c2细胞。与对照组相比,模型组H9c2细胞凋亡率、ROS水平、MDA含量显著升高(P0.05),线粒体膜电位、SOD、CAT含量及MEK1/2、ERK1/2磷酸化水平显著降低(P0.05);与模型组相比,5μmol/L阿托伐他汀组、10μmol/L阿托伐他汀组和15μmol/L阿托伐他汀组H9c2细胞凋亡率、ROS水平、MDA含量依次降低(P0.05),线粒体膜电位、SOD、CAT含量及MEK1/2、ERK1/2磷酸化水平依次升高(P0.05)。结论阿托伐他汀可能通过激活MEK/ERK通路降低Hcy诱导的H9c2细胞氧化应激反应,减轻心肌线粒体损伤。     

Rho/ROCK与神经系统疾病

作为一种分子开关,Rho可在无活性的GDP结合形式和有活性的GTP结合形式之间转换,传递信号给下游底物Rho激酶(ROCK),介导特殊的生物学效应,参与多种神经系统疾病,如缺血性卒中、脑血管痉挛、脊髓损伤后轴突再生的病理学过程.应用ROCK抑制剂治疗神经系统疾病已取得满意效果.Rho/ROCK有望成为一个新的治疗靶点.     

Novel and uncommon isoforms of the calcium sensing enzyme calcium/calmodulin dependent protein kinase II in heart tissue

Calcium/calmodulindependent protein kinase type II (CaM kinase II) is an intracellular enzyme discovered several years ago in the brain which is obviously involved in intracellular signal transmission. Meanwhile it was detected in virtually every mammalian tissue. Several isoforms have been found to exist. Most recently the tissue distribution and the molecular structure of these isoforms have suggested that each form entails a particular function. In the present study we describe the identification, cloning, and nucleotide sequencing of two novel CaM kinase II isoforms which we discovered in rat heart. The presence of these additional subtypes makes the heart the organ which possesses the greatest number of different and unusual CaM kinase II isoforms throughout the body except for the brain. The importance of this finding is underscored by the fact that calcium is involved in the regulation of many crucial cardial parameters. The deduced amino acid sequence that we have obtained from the new CaM kinase II isoforms indicates a molecular organization which could make the design of subtype-specific inhibitory drugs for CaM kinase II possible. Such compounds would act similarly to but much more selectively than digitalis glycosides and would be likely to possess less side effects.