上皮钙黏素及埃兹蛋白在胃癌和淋巴结转移灶中的表达及其意义

目的 检测胃腺癌组织和淋巴结转移灶中细胞骨架相关蛋白上皮钙黏素(E-cad)及埃兹蛋白(Ezrin)的表达,观察其与胃腺癌侵袭和转移的关系,探讨胃腺癌的浸润和转移机制.方法 用SP免疫组织化学法检测80例胃癌和40例淋巴结转移灶中E-cad和Ezrin的表达.结果 E-cad和Ezrin在癌旁正常胃黏膜上皮为胞膜表达,而在胃腺癌组织中E-cad出现胞膜、胞质两种表达形式,Ezrin在肿瘤细胞中则为胞质表达.在胃腺癌原发灶中,E-cad、Ezrin的表达与胃腺癌的分化程度相关.E-cad的膜表达及Ezrin的表达随分化程度降低而下降(P＜0.01;P＜0.05),E-cad的浆表达随分化程度降低而升高(P＜0.01).E-cad浆表达的升高与浸润深度、淋巴结状态相关且在原发灶显著高于转移灶(P＜0.01;P＜0.05;P＜0.01).在淋巴结转移灶中,E-cad的膜表达在淋巴结转移的早期阶段高于晚期阶段(P＜0.05).另外,E-cad膜表达及Ezrin的表达呈正相关(P＜0.01).结论 胃腺癌中E-cad的表达异常导致了细胞之间的黏附力下降,从而在胃腺癌的侵袭和转移中发挥重要作用.埃兹蛋白参与调节胃腺癌细胞的分化,可能通过与E-cadherin/catenin作用来调控肿瘤细胞的黏附和侵袭.     

气道平滑肌生物力学与哮喘病理机制的研究进展

哮喘病是危害人类健康的重要呼吸疾病,但其病理机制至今依然不完全清楚。由于呼吸依赖于各级肺组织在外力作用下的一系列力学过程,其力学因素必定在呼吸功能方面发挥着重要作用。其中,气道平滑肌细胞对物理环境很敏感,异常的力学因素刺激将可能改变气道平滑肌细胞的结构和／或功能,导致气道平滑肌过度收缩等病理变化。近年来,人们对气道平滑肌生物力学及其在哮喘的病理机制中的作用展开了大量研究,获得了许多重要的发现。本文将围绕气道平滑肌与肺中的力学环境介绍有关研究的最新进展,包括气道平滑肌收缩和骨架纤维的组织结构,气道平滑肌功能长度范围以及适应性,力学刺激引起的气道平滑肌细胞结构和功能的变化,气道平滑肌紧张度对应变诱导的响应的调控,细胞骨架软玻态动力学行为等,并探讨气道平滑肌生物力学与哮喘病病理机制的关系。     

慢性不可预见性温和应激后大鼠行为及海马细胞支架的改变

目的研究慢性不可预见性温和应激所致的动物行为学改变及细胞支架微管系统的动态性改变。方法将大鼠随机分为应激模型组（8只,以下简称模型组）和对照组（8只）,对模型组大鼠进行连续21d的慢性不可预见性应激。进行行为学观察,使用western blotting检测乙酰化微管蛋白（Acet—Tub）,酪氨酸微管蛋白（Tyr—Tub）。结果（1）模型组大鼠慢性应激后糖水偏好及自主活动显著减低,与对照组有显著差异;（2）模型组大鼠慢性应激后海马Acet—Tub表达升高,Tyr—Tub表达减低,与对照组有显著差异。结论慢性应激后微管动态性减低,神经可塑性受损。     

Effect of Nitric Oxide on Histamine-Induced Cytological Transformations in Parietal Cells in Isolated Human Gastric Glands

Previous studies have shown that nitric oxide (NO) inhibits histamine-induced gastric acid secretion in isolated human gastric glands. NO synthase has been found to be present in the human oxyntic mucosa and has been suggested to serve as a paracrine regulator of gastric acid secretion. Histamine stimulation of parietal cells induces cytoskeletal rearrangements, recruitment of H⁺/K⁺-ATPase-rich tubulovesicles to the apical membrane and expansion of intracellular canaliculi. The aim of the present study was thus to investigate (i) the effect of an NO donor on histamine-induced cytological transformations and (ii) the influence of increased [Ca²⁺]_i on NO-induced morphological changes in human parietal cells. Human gastric glands were isolated and subjected to the NO donor SNAP prior to histamine administration. [Ca²⁺]_i was increased by photolysis of the caged Ca²⁺ compound NP-EGTA. The distribution of F-actin, ezrin, and H⁺/K⁺-ATPase was assessed by confocal microscopy. Ultrastructural analysis was performed using transmission electron microscopy. SNAP did not influence the histamine-induced translocation of F-actin, ezrin, and H⁺/K⁺-ATPase but prevented an increase in the canalicular size. Elevation of [Ca²⁺]_i in resting cells was found to mimic histamine-induced intraparietal cell transformations; however, NO-induced parietal cell morphology was unaffected by a rise in [Ca²⁺]_i. These results indicate that NO inhibits secretion of fluid into the canalicular lumen without affecting membrane recruitment and that this effect is Ca²⁺-insensitive.     

Role of an alternatively spliced form of alphaII-spectrin in localization of connexin 43 in cardiomyocytes and regulation by stress-activated protein kinase

Decreases in the expression of connexin 43 and the integrity of gap junctions in cardiac muscle, induced by the constitutive activation of the c-Jun N-terminal kinase (JNK) signaling pathway, have been linked to conduction defects and sudden cardiac failure in mice [Petrich BG, Gong X , Lerner DL , Wang X , Brown JH , Saffitz JE , Wang Y. c-Jun N-terminal kinase activation mediates downregulation of connexin 43 in cardiomyocytes. Circ Res. 91 (2002) 640-647; B.G. Petrich, B.C. Eloff, D.L. Lerner, A. Kovacs, J.E. Saffitz, D.S. Rosenbaum, Y. Wang, Targeted activation of c-Jun N-terminal kinase in vivo induces restrictive cardiomyopathy and conduction defects. J. Biol. Chem. 2004;279: 15330-15338]. We examined the membrane cytoskeletal protein, alphaII-spectrin, which associates with connexin 43, to learn if changes in its association with connexin 43 are linked to the instability of gap junctions. Several forms of alphaII-spectrin are expressed in the heart, including one, termed alphaII-SH3i, which contains a 20-amino-acid sequence next to the SH3 domain of repeat 10. In adult mouse heart, antibodies to all forms of alphaII-spectrin labeled the sarcolemma, transverse ("t-") tubules and intercalated disks of cardiomyocytes. In contrast, antibodies specific for alphaII-SH3i labeled only gap junctions and transverse tubules. In transgenic hearts, in which the JNK pathway was constitutively activated, alphaII-SH3i was lost specifically from gap junctions but not from t-tubules while other isoforms of alphaII-spectrin were retained at intercalated disks. Immunoprecipitations confirmed the decreased association of alphaII-SH3i with connexin 43 in transgenic hearts compared to controls. Furthermore, activation of JNK in neonatal myocytes blocked the formation of gap junctions by exogenously expressed Cx43-GFP fusion protein. Similarly, overexpression of the SH3i fragment in the context of repeats 9-11 of alphaII-spectrin specifically caused the accumulation of Cx43-GFP in the perinuclear region and inhibited its accumulation at gap junctions. These results support a critical role for the alphaII-SH3i isoform of spectrin in intracellular targeting of Cx43 to gap junctions and implicates alphaII-SH3i as a potential target for stress signaling pathways that modulate intercellular communication.     

A Cytoskeleton Motor Protein Genetic Variant May Exert a Protective Effect on the Occurrence of Multiple Sclerosis: The Janus Face of the Kinesin Light-Chain 1 56836CC Genetic Variant

Although the main pathomechanism of multiple sclerosis (MS) is not known, an autoimmune response is presumed to involve its evolution and propagation. In this study, we examined how the kinesin light-chain 1 (KLC1) G56836C (rs8702) single nucleotide polymorphism (SNP) in intron 13 affects the occurrence of MS. This genetic variant was found to be associated with cognitive disturbances and neurodegeneration, and it was presumed to affect the kinesin function. Kinesin serves as a main cytoskeleton motor protein by carrying mitochondria and the molecular apparatus of myelin basic protein synthesis. The present association analysis of this genetic variant was performed in 102 relapsing-remitting MS patients and in 207 neuroimaging alteration-free controls. The KLC1 56836CC variant proved to exert a significant protective effect on the occurrence of MS (2.0% vs. 9.7%, P < 0.02; crude OR: 0.19, 95% CI: 0.04–0.82, P < 0.05; adjusted OR: 0.21, 95% CI: 0.018–0.88, P < 0.05). Our results draw attention to possible roles of the cytoskeleton in MS.     

8-甲氧沙林对黑素细胞内游离钙浓度及细胞骨架蛋白形成的影响

目的:观察8-甲氧沙林对体外培养黑素细胞内游离钙浓度、细胞骨架蛋白形成的影响.方法:正常人黑素细胞取自包皮环切术切取的包皮,用激光共聚焦扫描显微镜检测细胞内游离钙浓度,用罗丹明结合毒伞素对细胞骨架蛋白进行特异性染色.结果:8-甲氧沙林可使细胞内游离钙离子浓度升高,促进黑素细胞骨架蛋白合成.结论:8-甲氧沙林可能通过诱导黑素细胞内钙离子浓度升高和细胞骨架actin蛋白生成,从而影响黑素细胞的迁移.     

Adverse effects of cyclosporine A on HSP25, alpha B-crystallin and myofibrillar cytoskeleton in rat heart

Cyclosporine (CsA) is a universally used immunosuppressive drug which induces adverse side effects in several organs, but its impact on the heart is still controversial.     

Alterations in cytoskeletal protein expression by mycophenolic acid in human mesangial cells requires Rac inactivation

In response to glomerular injury, mesangial cells are activated into myofibroblasts, which contribute to the physiopathology of glomerulosclerosis. We have previously shown that chronic treatment of cultured human mesangial cells with mycophenolic acid (MPA), a specific inhibitor of guanosine nucleotide synthesis, prevents their activation and alters cytoskeleton protein expression and associated functions, such as contractility and migratory capacity. The aim of the present study was to explore the mechanisms underlying MPA-induced mesangial cytoskeleton alterations. We therein show that coincubation with guanosine (100 microM) compensates for the effects of MPA on mesangial cell proliferation and migration, and prevents MPA-induced overexpression of alpha-smooth muscle actin (SMA) and basic calponin (b-calp), indicating that guanylates are involved in mesangial responses to MPA. MPA decreased the GTP-bound (active) form of both RhoA, Rac1 and Cdc42, and specifically altered the expression level of Rac1. Pharmacological inhibition of RhoA activity reduced expression of both SMA and calponin, whereas overexpression of a dominant-negative form of Rac1 increased SMA expression. Conversely, overexpression of constitutively active Rac1 resulted in SMA and b-calp down-regulation, and fully prevented their stimulation by MPA, indicating that Rac inactivation is responsible for MPA effects on mesangial cytoskeletal expression. These results show that in human mesangial cells, RhoA and Rac1 exert opposite effects on the expression of two major cytoskeletal proteins: SMA and basic calponin. Moreover, these data highlight for the first time an integrated mechanism whereby MPA regulates mesangial phenotype, which is mediated by loss of Rac activity.