小鼠神经母细胞瘤细胞中神经型钙黏蛋白超表达对突起形成及连环蛋白表达的影响

目的 探讨神经型钙黏蛋白（N-cadherin）调控连环蛋白（catenin）对小鼠神经母细胞瘤细胞（N2a）形态的影响。 方法 构建鼠源的N-cadherin融合蛋白超表达载体,利用脂质体转染的方法将空载体pCAG-MCS-EGFP和超表达载体pCAG-N-Cad-EGFP分别转染至N2a细胞,作为对照组和实验组;细胞划痕和黏附实验检测N-cadherin超表达对N2a细胞迁移和黏附的影响,免疫荧光检测N-cadherin超表达对N2a细胞形态的影响,并结合Western blotting检测连环蛋白家族的表达情况。 结果 与对照组相比,N-cadherin超表达促进细胞突起的形成,使得N2a细胞突起增多和伸长;N-cadherin超表达增强了黏附性而抑制了细胞的迁移能力;N-cadherin超表达使得细胞内连环蛋白家族中α-catenin、β-catenin和p120蛋白表达均显著上升（P<0.05）,而γ-catenin表达下降但差异不显著（P>0.05）;另外,N-cadherin超表达的细胞有明显的聚集现象。 结论 N-cadherin超表达促进N2a细胞突起形成,增强细胞的黏附性从而抑制细胞的迁移能力,调控连环蛋白家族成员的表达并促使细胞聚集。     

Cdc42 GTPase and Rac1 GTPase act downstream of p120 catenin and require GTP exchange during gastrulation of zebrafish mesoderm

Background : We investigated the roles of p120 catenin, Cdc42, Rac1, and RhoA GTPases in regulating migration of presomitic mesoderm cells in zebrafish embryos. p120 catenin has dual roles: It binds the intracellular and juxtamembrane region of cadherins to stabilize cadherin‐mediated adhesion with the aid of RhoA GTPase, and it activates Cdc42 GTPase and Rac1 GTPase in the cytosol to initiate cell motility. Results : During gastrulation of zebrafish embryos, knockdown of the synthesis of zygotic p120 catenin δ1 mRNAs with a splice‐site morpholino caused lateral widening and anterior‐posterior shortening of the presomitic mesoderm and somites and a shortened anterior‐posterior axis. These phenotypes indicate a cell‐migration effect. Co‐injection of low amounts of wild‐type Cdc42 or wild‐type Rac1 or dominant‐negative RhoA mRNAs, but not constitutively‐active Cdc42 mRNA, rescued these p120 catenin δ1‐depleted embryos. Conclusions : These downstream small GTPases require appropriate spatiotemporal stimulation or cycling of GTP to guide mesodermal cell migration. A delicate balance of Rho GTPases and p120 catenin underlies normal development. Developmental Dynamics 241:1545–1561, 2012. © 2012 Wiley Periodicals Inc.     

骨形态发生蛋白-7调节肾病鼠Wnt1/β-catenin信号通路

目的观察骨形态发生蛋白-7(BMP-7)对嘌呤霉素氨基核苷酸肾病(PAN)鼠肾小球Wnt/β-catenin表达的影响,探讨BMP-7的肾保护作用及可能机制。方法 20只嘌呤霉素氨基核苷酸诱导的大鼠随机分为PAN组和PAN+BMP-7组(BMP-7组),每组各10只。BMP-7组每周2次腹腔注射人重组BMP-7 30微克/(千克.次)。另设正常对照组(NC,n=10)。第12周检测尿液红细胞(UE)、24h尿蛋白(24h UP),血清半胱氨酸蛋白酶抑制剂(Cys C)、巨噬细胞移动抑制因子(MIF)。处死大鼠,反转录-聚合酶链反应检测Wnt1和β-catenin mRNA表达水平。Western blotting检测Wnt1和β-catenin蛋白表达水平。结果与NC组相比,PAN组UE、24h UP、Cys C、MIC、肾小球Wnt1和β-catenin mRNA和蛋白质的表达水平均显著升高,差异具有显著的统计学意义(P均<0.01)。BMP-6组UE、24h UP、Cys C、MIF、肾小球Wnt1和β-catenin mRNA和蛋白质的表达较PAN组降低,差异具有统计学意义(P<0.05或P<0.01)。结论 BMP-7减轻尿液红细胞及尿蛋白的排泄,降低血清CysC、MIC水平,下调肾小球Wnt1/β-catenin信号通路的表达,减轻肾损伤。     

Mechanisms of HER2-Induced Endothelial Cell Retraction

Background HER2 overexpression imparts a metastatic advantage in breast cancer. We have shown that HER2 signaling in breast cancer cells induces adjacent endothelial cell (EC) retraction, disrupting endothelial integrity. Because endothelial integrity is dependent on the adherens junctions, we postulated that the mechanism of tumor cell-induced EC retraction involves dissociation of catenin proteins from vascular endothelial (VE) cadherin. In this study, we report a loss of VE-cadherin in tumor-associated EC. We also tested for a change of catenin dissociation from VE-cadherin by manipulating HER2 signaling in tumor cells. Methods We tested confluent monolayers of human EC for downregulation of VE cadherin and dissociation of catenins from VE cadherin after exposure to breast cancer cells or conditioned media. Using immunoprecipitation, we quantitated the remaining complexed catenins to VE-cadherin in tumor-associated EC after different treatments to manipulate HER2 signaling. Results Treatment of EC with conditioned media from MCF-7 cells expressing HER2 induced a loss of VE-cadherin expression, and time-dependent dissociation of catenins from VE cadherin. Catenin dissociation from VE-cadherin was enhanced by Heregulin β1 (P < .05) stimulation and decreased by trastuzumab (P < .05) blockade of HER2 signaling in cancer cells. An increase in EC phosphoSrc (Tyr 416) was seen by 8 hours. Conclusions Our data suggest that HER2 induction of EC retraction involves both down-regulation of VE-cadherin and dissociation of catenins. HER2 signaling appears to regulate this potential metastatic mechanism. Further, Src phosphorylation suggests that this pathway may be involved in this mechanism.     

E‐cadherin expression increases cell proliferation by regulating energy metabolism through nuclear factor‐κB in AGS cells

β‐Catenin is a central player in Wnt signaling, and activation of Wnt signaling is associated with cancer development. E‐cadherin in complex with β‐catenin mediates cell–cell adhesion, which suppresses β‐catenin‐dependent Wnt signaling. Recently, a tumor‐suppressive role for E‐cadherin has been reconsidered, as re‐expression of E‐cadherin was reported to enhance the metastatic potential of malignant tumors. To explore the role of E‐cadherin, we established an E‐cadherin‐expressing cell line, EC96, from AGS cells that featured undetectable E‐cadherin expression and a high level of Wnt signaling. In EC96 cells, E‐cadherin re‐expression enhanced cell proliferation, although Wnt signaling activity was reduced. Subsequent analysis revealed that nuclear factor‐κB (NF‐κB) activation and consequent c‐myc expression might be involved in E‐cadherin expression‐mediated cell proliferation. To facilitate rapid proliferation, EC96 cells enhance glucose uptake and produce ATP using both mitochondria oxidative phosphorylation and glycolysis, whereas AGS cells use these mechanisms less efficiently. These events appeared to be mediated by NF‐κB activation. Therefore, E‐cadherin re‐expression and subsequent induction of NF‐κB signaling likely enhance energy production and cell proliferation.     

FHIT、β-Catenin在胃癌中表达及其相关性研究

目的探讨胃癌中FHIT和β—Catenin的表达相关性及其与胃癌发展之间的关系。方法应用免疫组化法检测50例胃癌组织、10例胃良性病变组织标本中FHIT和β—Catenin表达。结果胃癌组织FHIT和β—Catenin的阳性表达率分别为22．00％和78．00％。FHIT在胃癌组织中表达缺失,与浸润深度和淋巴结转移关系密切（P〈0．05）,与患者的性别、年龄、肿瘤大小及分化程度无关（P〉0．05）。β—Catenin在胃癌组织中高表达与浸润深度、肿瘤大小及分化程度和淋巴结转移关系密切（P〈0．05）,与患者的性别、年龄无关（P〉0．05）。癌组织中FHIT和β—Catenin的表达呈负相关（r=-0.358,P=0．011）。结论FHIT和β-Catenin在胃癌中表达成显著负相关,提示两者在胃癌的发生发展中可能存在重要的协同作用。     

Role of androgens and glucocorticoids in the regulation of diazepam-binding inhibitor mRNA levels in male mouse hypothalamus

Receptor protein tyrosine phosphatase rho (RPTPrho/PTPRT) is a transmembrane protein that is highly expressed in the developing and adult central nervous system. It is a member of the RPTP R2B subfamily, which includes PTPkappa, PTPmu and PCP-2. Glutathione-S-transferase (GST) pulldown assays were used to show that RPTPrho interacts with several adherens junctional proteins in brain, including E-cadherin, N-cadherin, VE-cadherin (cadherin-5), desmoglein, alpha, beta and gamma catenin, p120(ctn) and alpha-actinin. With the exception of E-cadherin and alpha-actinin, binding was considerably reduced at high sodium concentrations. Furthermore, immunoprecipitation phosphatase assays indicated that E-cadherin, and to a far lesser extent p120(ctn), were tyrosine dephosphorylated by a recombinant RPTPrho intracellular fragment, and thus, were likely to be primary substrates for RPTPrho. The interaction of RPTPrho with adherens junctional components suggests that this phosphatase may transduce extracellular signals to the actin cytoskeleton and thereby play a role in regulating cadherin-mediated cell adhesion in the central nervous system.     

β-tubulin-Ⅲ、E-cadherin和α-catenin在乳腺癌及癌前病变中的表达及诊断意义

目的探讨乳腺癌前病变及浸润性癌中β-tubulin-Ⅲ、E-cadherin和α-catenin的表达及诊断意义。 方法采用免疫组织化学UltraSensitiveTM S-P法检测20例乳腺非典型导管上皮增生(ADH)、60例乳腺导管原位癌(DCIS)和90例浸润性乳腺癌(IDC)中的β-tubulin-Ⅲ、E-cadherin和α-catenin的表达,以30例正常乳腺组织作对照。 结果β-tubulin-Ⅲ微管蛋白的表达：(1)β-tubulin-Ⅲ微管蛋白在正常对照组、ADH、DCIS和IDC组中表达率为22.0%,55.0%,71.7%,84.4%,4组间差异有统计学意义(χ²＝22.298,P<0.05),两两组间比较,导管原位癌组、浸润性导管癌组与非典型导管增生组、正常对照组比较均差异有统计学意义(χ²＝39.525,22.474,6.551,P<0.05)。2. E-cadherin和α-catenin的表达：在正常对照组、ADH、DCIS和IDC组中,E-cadherin的表达率分别为100%、75.0%、68.3%和41.1%,α-catenin的表达率为100.0%、80.0%、73.3%和56.7%,在四组中E-cadherin和α-catenin的表达差异有统计学意义(χ²＝18.65,10.97,P<0.05)。 结论乳腺癌前病变中β-tubulin-Ⅲ过表达,可能是乳腺癌形成的早期事件;E-cadherin和α-catenin在乳腺细胞过度增殖、恶性转化的过程中起重要作用,可作为判断组织病变程度及侵袭能力强弱的因素,β-tubulin-Ⅲ微管蛋白及E-cadherin、α-catenin有可能成为诊断和评估乳腺癌变和治疗的指标。     

FH535抑制人肝癌细胞HepG2增殖及cyclin D表达

目的 探讨β-catenin抑制剂FH535对人肝癌细胞系HepG2增殖的影响及可能机制.方法 HepG2细胞分为对照组和FH535用药组,使用改良3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐比色法(MTS)检测FH535对HepG2细胞增殖的影响,以Western blot法检测HepG2细胞β-catenin以及cyclin D蛋白表达水平,用实时荧光定量聚合酶链式反应(PCR)检测HepG2细胞cyclin D mRNA水平.结果 FH535能够显著抑制HepG2细胞的增殖,呈时间和剂量依赖性.与对照组相比,FH535给药组HepG2细胞内β-catenin蛋白表达无差异.FH535给药组细胞wnt/β-catenin信号通路的靶基因cyclin D的mRNA和蛋白的表达显著下降,与对照组相比差异有统计学意义(P<0.0001).结论 FH535通过抑制cyclin D mRNA及cyclin D蛋白表达而抑制HepG2细胞增殖.