MMP-2和TIMP-2基因启动子区多态性与卵巢上皮性癌关系的研究

为探讨MMP-2和TIMP-2基因启动子区单核苷酸多态性(SNPs)与卵巢上皮性癌发病风险的关系, 采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法检测了246例卵巢上皮性癌患者和324例对照妇女的MMP-2 C-1306T、C-735T和TIMP-2 G-418C 3个SNPs的基因型。结果显示, MMP-2 C-1306T SNP的等位基因及基因型频率分布在卵巢癌与对照组间无显著差异(P=0.55和P=0.42); 但卵巢癌组MMP-2 C-735T SNP的C等位基因和C/C基因型频率(80.7%和66.7%)明显高于对照组(75.5%和55.9%), 与T/T+C/T基因型比较, 携带C/C基因型可以显著增加卵巢癌的发病风险(OR=1.58, 95% CI=1.12~2.23), 进一步分层分析显示, C/C基因型主要与宫内膜样癌和年龄≥50岁妇女的发病风险显著相关, OR值分别为1.69(95%CI=1.03~2.79)和1.71(95% CI=1.14~2.57); 对MMP-2 C-1306T、C-735T 2个SNPs的单体型分析显示, 4种单体型频率(T_-1306-T_-735、T_-1306-C_-735、C_-1306-T_-735和C_-1306-C_-735)在两组间分布无显著差异(P=0.24); 虽然TIMP-2 G-418C SNP的等位基因及基因型频率在卵巢癌组与对照组间分布无显著性差异(P=0.33和P=0.47), 但以病理类型分层分析显示, 携带TIMP-2 G-418G/G基因型有增加宫内膜样癌发病风险的趋势(OR=1.62, 95%CI=0.94~2.78)。以上结果提示, MMP-2基因启动子区C-735T SNP的C/C基因型可能是卵巢上皮性癌发病的潜在危险因素, 而C-1306T SNP可能与卵巢上皮性癌的发病风险无关; TIMP-2 G-418C SNP可能与不同病理类型的卵巢上皮性癌发病风险有关。     

MMP-9 and MMP-2 gelatinases and TIMP-1 and TIMP-2 inhibitors in breast cancer: correlations with prognostic factors

The goal of our study was to analyse the prognostic values for some matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in breast cancer. We evaluated the activity and the expression levels of MMP-9, MMP-2, TIMP-1 and TIMP-2 in malignant versus benign fresh breast tumor extracts. For this purpose, gelatinzymography, immunoblotting and ELISA were used to analyse the activity and expression of MMPs and TIMPs. We found that MMP-9 expression level and activity are increased in malignant tumors. In addition, MMP-9/TIMP-1 and MMP-2/TIMP-2 ratio values obtained by us were significantly different in malignant tumors compared to benign tumors. We suggest that the abnormal MMP-9/TIMP-1 balance plays a role in the configuration of breast invasive carcinoma of no special type and also in tumor growth, while altered MMP-2/TIMP-2 ratio value could be associated with lymph node invasion and used as a prognostic marker in correlation with Nottingham Prognostic Index. Finally, we showed that in malignant tumors high expression of estrogen receptors is associated with enhanced activity of MMP-2 and increased bcl- 2 levels, while high expression of progesterone receptors is correlated with low TIMP-1 protein levels.     

蛋白酪氨酸磷酸酶SHP-1/SHP-2催化活性域的表达和动力学分析

为了分离纯化SHP-1/SHP-2催化活性域蛋白(分别命名为D1C/D2C), 并估测其动力学常数, 将已经构建好的D1C/D2C重组质粒转化Escherichia coli BL21菌株, 经IPTG诱导表达、菌体裂解缓冲液悬浮和超声波破碎后, 通过HPLC分离纯化D1C/D2C蛋白, 所得产物进行SDS-PAGE电泳检测。然后, 以pY作为去磷酸化反应的底物, 利用孔雀绿显色法, 通过双倒数作图法对纯化的D1C/D2C蛋白进行动力学分析。结果表明, 本试验已成功地表达了D1C和D2C蛋白, 主要以可溶性蛋白的形式表达; 利用HPLC技术可有效地对D1C/D2C蛋白进行分离纯化; D1C的相对分子质量为34.6 kD, 米氏常数Km=2.04 mmol/L, 催化常数Kcat=44.98 s, 特异性常数Kcat/Km=22.05 L/(mmol·s); D2C的相对分子质量为35.3 kD, 米氏常数Km=2.47 mmol/L, 催化常数Kcat=27.45 s, 特异性常数Kcat/Km=11.11 L/(mmol·s); D1C的磷酸酶活性较强于D2C。     

MMP-2及TIMP-2的表达与胶质瘤复发相关性的研究

目的:探讨基质金属蛋白酶类与胶质细胞瘤浸润性生长之间的关系及其在胶质瘤复发中的作用。以及基质金属蛋白酶及其抑制因子(MMP-2、TIMP-2)的阳性表达与胶质细胞瘤病理分级及预后的关系。方法:应用免疫组织化学染色法(SP法)检测48例人脑原发和复发胶质细胞瘤组织中MMP-2、TIMP-2的表达。结果:Ⅲ、Ⅳ级和复发胶质细胞瘤中的MMP-2蛋白的表达显著高于Ⅰ、Ⅱ级(P<0.05);Ⅰ、Ⅱ级胶质细胞瘤中的TIMP-2蛋白的表达显著高于复发胶质细胞瘤(P<0.05)而与Ⅲ、Ⅳ级细胞瘤无显著性差异(P>0.05);Ⅲ、Ⅳ级和复发胶质细胞瘤中的MMP-2,TIMP-2蛋白的表达无显著差异(P>0.05);同级别胶质细胞瘤中MMP-2、TIMP-2的表达之间无明显相关性(P>0.05);正常脑组织中无表达。结论:MMP-2、TIMP-2的表达与胶质细胞瘤的恶性程度有关,低级别中,MMP-2与TIMP-2成正相关;MMP-2的高表达,TIMP-2的低表达与胶质细胞瘤的侵袭有关,MMP-2、TIMP-2的表达水平有可能成为判定胶质细胞瘤恶性程度、侵袭能力和预后的诊断指标,而且TIMP-2可能更加敏感。     

SHP-2 inhibits tyrosine phosphorylation of Cas-L and regulates cell migration

The Src homology 2 (SH2) domain-containing protein tyrosine phosphatase, SHP-2, plays an important role in cell migration by interacting with various proteins. In this report, we demonstrated that SHP-2 inhibits tyrosine phosphorylation of Crk-associated substrate lymphocyte type (Cas-L), a docking protein which mediates cell migration, and found that SHP-2 negatively regulates migration of A549 lung adenocarcinoma cells induced by fibronectin (FN). We showed that overexpressed SHP-2 co-localizes with Cas-L at focal adhesions and that exogenous expression of SHP-2 abrogates cell migration mediated by Cas-L. SHP-2 inhibits tyrosine phosphorylation of Cas-L, and associates with Cas-L to form a complex in a tyrosine phosphorylation-dependent manner. Finally, immunoprecipitation experiments with deletion mutants revealed that both SH2 domains of SHP-2 are necessary for this association. These results suggest that SHP-2 regulates tyrosine phosphorylation of Cas-L, hence opposing the effect of kinases, and SHP-2 is a negative regulator of cell migration mediated by Cas-L.     

Specific SHP-2 partitioning in raft domains triggers integrin-mediated signaling via Rho activation

Cell signaling does not occur randomly over the cell surface, but is integrated within cholesterol-enriched membrane domains, termed rafts. By targeting SHP-2 to raft domains or to a non-raft plasma membrane fraction, we studied the functional role of rafts in signaling. Serum-depleted, nonattached cells expressing the raft SHP-2 form, but not non-raft SHP-2, display signaling events resembling those observed after fibronectin attachment, such as beta1 integrin clustering, 397Y-FAK phosphorylation, and ERK activation, and also increases Rho-GTP levels. Expression of the dominant negative N19Rho abrogates raft-SHP-2-induced signaling, suggesting that Rho activation is a downstream event in SHP-2 signaling. Expression of a catalytic inactive SHP-2 mutant abrogates the adhesion-induced feedback inhibition of Rho activity, suggesting that SHP-2 contributes to adhesion-induced suppression of Rho activity. Because raft recruitment of SHP-2 occurs physiologically after cell attachment, these results provide a mechanism by which SHP-2 may influence cell adhesion and migration by spatially regulating Rho activity.     

博莱霉素致肺间质成纤维细胞MMP-2/TIMP-1表达失衡

观察博莱霉素对肺间质成纤维细胞中基质金属蛋白酶-2（MMP-2）及组织金属蛋白酶抑制剂-1（TIMP-1）表达的影响,探讨博莱霉素引起肺纤维化的机制。体外培养肺间质成纤维细胞,并向培养基中加入博莱霉素,在作用不同时间后收集样本,采用酶谱图测定细胞培养上清液中MMP-2酶活性、ELISA测定TIMP-1量,免疫组织化学法检测细胞中MMP-2、TIMP-1的原位表达,RT-PCR法检测MMP-2和TIMP-1的mRNA水平。结果发现,博莱霉素在2h、12h促进MMP-2的分泌,24h后无促分泌作用;而2-48h,MMP-2的原位表达及mRNA均不受博莱霉素的影响;博莱霉素从12h开始促进TIMP-1及mRNA的表达,并持续至48h。结果表明博莱霉素可引起肺间质戍纤维细胞MMP-2／TIMP-1表达失衡,并可能参与肺纤维化的发生。     

大豆异黄酮对MMTV-erbB-2 转基因小鼠乳腺肿瘤中MMP-2 和TIMP-2 表达影响的研究

目的:利用MMTV-erbB-2转基因小鼠,探讨食物中大豆异黄酮对MMTV-erbB-2转基因小鼠乳腺肿瘤发生发展的影响。方法:选择健康雌性MMTV-erbB-2转基因小鼠60只,随机分为实验组(自鼠龄四周起喂养含有大豆异黄酮的豆饲料和对照组(喂养不含大豆异黄酮的普通饲料)。观察两组小鼠生长情况,观察各组小鼠乳腺肿瘤的发病率和潜伏期、记录肿瘤生长情况,并通过HE染色观察其病理类型,免疫组织化学染色SP法检测各组小鼠乳腺癌组织及正常乳腺组织中MMP-2和TIMP-2的表达并分析其关系。结果:豆饲料干预组,普通饲料干预组小鼠乳腺肿瘤的发瘤率分别为36.7%,66.7%,豆饲料干预组小鼠乳腺肿瘤发瘤率与对照饲料干预组相比明显降低,差异有统计学意义(P<0.05)。小鼠肿瘤多生长在第2-3对乳腺上,两组小鼠乳腺肿瘤最大平均直径及潜伏期相比较差异无统计学意义。两实验组小鼠乳腺肿瘤组织经HE染色后全部确定为乳腺癌组织。两实验组小鼠乳腺肿瘤组织中MMP-2和TIMP-2表达均高于正常乳腺组织,差异有统计学意义(P<0.05),MMP-2和TIMP-2在乳腺肿瘤组织中表达呈负相关,在正常乳腺组织中表达无相关性。MMP-2在豆饲料干预组,普通饲料干预组小鼠乳腺肿瘤组织中的阳性率分别为83.3%,73.9%,各实验组阳性率相比较差异无统计学意义(P=0.888);TIMP-2在豆饲料干预组,普通饲料干预组小鼠乳腺肿瘤组织中的阳性率分别为33.3%,43.5%,各实验组阳性率相比较差异无统计学意义。结论:大豆异黄酮能抑制MMTV-erbB-2转基因小鼠乳腺肿瘤的发生,但其对小鼠乳腺肿瘤的作用与MMP-2及TIMP-2的表达无明显相关,具体机制尚待进一步研究。     

茶多酚对Lewis 肺癌小鼠移植瘤MMP-2、TIMP-2 表达的影响

目的:观察茶多酚对肺癌小鼠移植瘤基质金属蛋白酶-2(MMP-2)及其相应的组织金属蛋白酶抑制剂-2(TIMP-2)表达的影响,探讨茶多酚抗新生血管生成的效应机制。方法:建立57小鼠肺癌移植瘤模型,测定茶多酚低、高剂量组以及茶多酚联合沙利度胺组的肿瘤抑制率,并且采用免疫组化法检测各组MMP-2、TIMP-2表达水平以及MMP-2/TIMP-2比值,以探讨其抗肿瘤的分子机制。结果:实验表明,茶多酚有如下作用:①沙利度胺组、茶多酚低剂量组、茶多酚高剂量组、茶多酚低剂量联合沙利度胺组、茶多酚高剂量联合沙利度胺组的肿瘤抑制率分别为17.26%、16.94%、20.81%、21.94%和44.32%,茶多酚高剂量联合沙利度胺组与模型组瘤重比较,有统计学意义(P<0.05);②茶多酚各组及联合用药各组能下调肿瘤组织MMP-2蛋白表达,茶多酚高剂量联合沙利度胺组能上调TIMP-2蛋白表达,与模型对照组比较,均具有统计学意义(P<0.05);③用药各组MMP-2/TIMP-2比值均有所下降,茶多酚各组明显降低,茶多酚大剂量联合沙利度胺组比值下降最为显著。结论:茶多酚高剂量联合沙利度胺组对肺癌有明显抑制作用。其机制可能与下调MMP-2表达、上调TIMP-2表达、调整MMP-2/TIMP-2比值失衡状态,从而抗肺癌新生血管生成相关。     

急性肺损伤大鼠肺组织基质金属蛋白酶2及其抑制因子蛋白和mRNA的表达

目的探讨内毒素致急性肺损伤（ALI）大鼠肺组织核转录因子-κB（NF-κB）、基质金属蛋白酶2（MMP-2）及其抑制因子（TIMP-2）蛋白和mRNA表达的变化。方法 20只雄性Wistar大鼠随机分为2组：对照组、LPS模型组,每组再分为4 h和8 h两个亚组。尾静脉注射脂多糖（LPS）（10 mg/kg）建立大鼠急性肺损伤模型。检测血白细胞计数、支气管肺泡灌洗液（BALF）蛋白含量,采用免疫组化ABC法和实时荧光定量PCR分别测定肺组织NF-κB、MMP-2、TIMP-2蛋白及其mRNA的表达,并观察肺组织病理变化。结果与对照组相比,模型组4 h和8 h时大鼠肺组织中的NF-κB、MMP-2蛋白染色阳性面积率及其mRNA表达均显著增高（P〈0.01）、TIMP-2蛋白染色阳性面积率及其mRNA表达均明显降低（P〈0.05或P〈0.01）。病理学观察显示,模型组大鼠肺组织出现出血及坏死。结论内毒素致急性肺损伤的发病机制可能与NF-κB、MMP-2蛋白及其mRNA表达升高、TIMP-2蛋白及其mRNA表达降低有关。     

Protein-protein interaction between caveolin-1 and SHP-2 is dependent on the N-SH2 domain of SHP-2

Src homology 2-containing protein tyrosine phosphatase 2 (SHP-2) is known to protect neurons from neurodegeneration during ischemia/reperfusion injury. We recently reported that ROS-mediated oxidative stress promotes phosphorylation of endogenous SHP-2 in astrocytes and complex formation between caveolin-1 and SHP-2 in response to oxidative stress. To examine the region of SHP-2 participating in complex formation with caveolin-1, we generated three deletion mutant constructs and six point mutation constructs of SHP-2. Compared with wild-type SHP-2, binding of the N-SH2 domain deletion mutant of SHP-2 to p-caveolin-1 was reduced greatly, using flow cytometric competitive binding assays and surface plasmon resonance (SPR). Moreover, deletion of the N-SH2 domain of SHP-2 affected H₂O₂-mediated ERK phosphorylation and Src phosphorylation at Tyr 419 in primary astrocytes, suggesting that N-SH2 domain of SHP-2 is responsible for the binding of caveolin-1 and contributes to the regulation of Src phosphorylation and activation following ROS-induced oxidative stress in brain astrocytes. [BMB Reports 2015; 48(3): 184-189]     

The tyrosine phosphatase SHP-2 controls urokinase-dependent signaling and functions in human vascular smooth muscle cells

The urokinase (uPA)/urokinase receptor (uPAR) multifunctional system is an important mediator of functional behaviour of human vascular smooth muscle cells (VSMC). uPAR associates with platelet-derived growth factor receptor β (PDGFR-β), which serves as a transmembrane adaptor for uPAR in VSMC, to transduce intracellular signaling and initiate functional changes. The precise and rapid propagation of these signaling cascades demands both strict and flexible regulatory mechanisms that remain unexplored. We provide evidence that the tyrosine phosphatase SHP-2 mediates these processes. uPA regulated SHP-2 phosphorylation, catalytic activity, and its co-localization and association with the PDGFR-β. Active PDGFR-β was required for the uPA-induced SHP-2 phosphorylation. uPAR-directed STAT1 pathway was disturbed in cells expressing SHP-2 inactive mutant. Both, cell proliferation and migration were impaired in VSMC with downregulated SHP-2. Elucidating the underlying mechanisms, we found that uPA induced SHP-2 recruitment to lipid rafts. Disruption of rafts abolished uPA-related control of SHP-2 phosphorylation, its association with PDGFR-β and finally the VSMC functional responses. Our results demonstrate that SHP-2 plays an important role in uPA-directed signaling and functional control of human VSMC and suggest that this phosphatase might contribute to the pathogenesis of the uPA-related vascular remodeling.     

人源蛋白酪氨酸磷酸酶SHP-2基因克隆与原核表达

目的:构建蛋白酪氨酸磷酸酶SHP-2的原核表达载体并在大肠杆菌中表达。方法:以人脑组织mRNA为模板,通过RT-PCR扩增出目标cDNA,构建蛋白酪氨酸磷酸酶SHP-2-pEASY-E1重组质粒。将重组质粒转化进E.coli TOP10感受态细胞中,通过菌落PCR和测序进行阳性克隆的筛选和验证,将正确的质粒转化E.coli Transetta感受态细胞中,通过SDS-PAGE和western-blot进行蛋白检测和验证,酶促动力学分析SHP-2可溶性蛋白的活性。结果:成功克隆SHP-2功能域,构建SHP-2-pEASY-E1原核表达载体,完成可溶性蛋白的表达;酶促动力学分析结果为:米氏常数Km=0.97mmol/L,Vmax为13.57mmol/L/s。结论:本研究成功构建SHP-2的原核表达载体,重组表达的SHP-2蛋白具有较高的磷酸酶活性。     

TIMP-2 promotes cell spreading and adhesion via upregulation of Rap1 signaling

We previously demonstrated that TIMP-2 treatment of human microvascular endothelial cells (hMVECs) activates Rap1 via the pathway of paxillin-Crk-C3G. Here, we show that TIMP-2 overexpression in hMVECs by adenoviral infection enhances Rap1 expression, leading to further increase in Rap1-GTP. TIMP-2 expression, previously reported to inhibit cell migration, also leads to cell spreading accompanied with increased cell adhesion. HMVECs stably expressing Rap1 display a similar phenotype as hMVECs-TIMP-2, whereas the expression of inactive Rap1 mutant, Rap1(38N), leads to elongated appearance with greatly reduced cell adhesion. Furthermore, the phenotype of hMVECs-Rap1(38N) was not reversed by TIMP-2 overexpression. TIMP-2 greatly promotes the association of Rap1 with actin. Therefore, these findings suggest that TIMP-2 mediated alteration in cell morphology requires Rap1, TIMP-2 may recruit Rap1 to sites of actin cytoskeleton remodeling necessary for cell spreading, and enhanced cell adhesion by TIMP-2 expression may hinder cell migration.     

MMP-9、TIMP-1及细菌L型在卵巢乳头状癌中的表达及意义

目的探讨MMP-9、TIMP-1及细菌L型在卵巢上皮性肿瘤中的表达及临床意义。方法采用原位杂交和免疫组化及革兰染色方法检测97例卵巢乳头状癌及23例卵巢乳头状瘤组织中MMP-9、TIMP-1的表达及细菌L型检出率,并用2χ检验进行统计学处理。结果卵巢乳头状癌中MMP-9及TIMP-1的表达率均明显高于良性肿瘤(P<0.005)。MMP-9在卵巢乳头状癌中临床分期Ⅲ、Ⅳ期中的表达率明显高于Ⅰ、Ⅱ期(P<0.005~P<0.01),随着病理分级增高而显著增加(P<0.005~P<0.05),腹腔淋巴结有转移和有腹水者均高于无腹腔淋巴结转移和无腹水者(P<0.005~P<0.05)。而TIMP-1阳性表达与MMP-9阳性表达相反,呈负相关。细菌L型检出阳性率与病理分级及临床分期差异有显著性,腹腔淋巴结有转移比无转移者、有腹水比无腹水者差异有显著性(P<0.005)。结论MMP-9、TIMP-1基因及蛋白在卵巢肿瘤中有不同程度的异常表达,两者均可作为判断卵巢肿瘤生物学行为及患者预后参考指标。L型感染极有可能成为诱发肿瘤因素之一,它与MMP-9、TIMP-1可能有协同致瘤及恶性肿瘤侵袭和转移作用。研究细菌L型感染与肿瘤的关系,具有重要的临床应用价值。     

Tissue inhibitor of metalloproteinase-2 (TIMP-2) regulates myogenesis and beta1 integrin expression in vitro

Myogenesis in vitro involves myoblast cell cycle arrest, migration, and fusion to form multinucleated myotubes. Extracellular matrix (ECM) integrity during these processes is maintained by the opposing actions of matrix metalloproteinase (MMP) proteases and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). Here, we report that TIMP-2, MMP-2, and MT1-MMP are differentially expressed during mouse myoblast differentiation in vitro. A specific role for TIMP-2 in myogenesis is demonstrated by altered TIMP-2(-/-) myotube formation. When differentiated in horse serum-containing medium, TIMP-2(-/-) myotubes are larger than wild-type myotubes. In contrast, when serum-free medium is used, TIMP-2(-/-) myotubes are smaller than wild-type myotubes. Regardless of culture condition, myotube size is directly correlated with MMP activity and inversely correlated with beta1 integrin expression. Treatment with recombinant TIMP-2 rescues reduced TIMP-2(-/-) myotube size and induces increased MMP-9 activation and decreased beta1 integrin expression. Treatment with either MMP-2 or MMP-9 similarly rescues reduced myotube size, but has no effect on beta1 integrin expression. These data suggest a specific regulatory relationship between TIMP-2 and beta1 integrin during myogenesis. Elucidating the role of TIMP-2 in myogenesis in vitro may lead to new therapeutic options for the use of TIMP-2 in myopathies and muscular dystrophies in vivo.     

Rational design of a SHP-2 targeted,fluorogenic peptide substrate

Protein tyrosine phosphatase (PTP) targeted, peptide based chemical probes are valuable tools for studying this important family of enzymes, despite the inherent difficulty of developing peptides targeted towards an individual PTP. Here, we have taken a rational approach to designing a SHP-2 targeted, fluorogenic peptide substrate based on information about the potential biological substrates of SHP-2. The fluorogenic, phosphotyrosine mimetic phosphocoumaryl aminopropionic acid (pCAP) provides a facile readout for monitoring PTP activity. By optimizing the amino acids surrounding the pCAP residue, we obtained a substrate with the sequence Ac-DDPI-pCAP-DVLD-NH₂ and optimized kinetic parameters (k_cat = 0.059 ± 0.008 s⁻¹, K_m = 220 ± 50 µM, k_cat/K_m of 270 M⁻¹s⁻¹). In comparison, the phosphorylated coumarin moiety alone is an exceedingly poor substrate for SHP-2, with a k_cat value of 0.0038 ± 0.0003 s⁻¹, a K_m value of 1100 ± 100 µM and a k_cat/K_m of 3 M⁻¹s⁻¹. Furthermore, this optimized peptide has selectivity for SHP-2 over HePTP, MEG1 and PTPµ. The data presented here demonstrate that PTP-targeted peptide substrates can be obtained by optimizing the sequence of a pCAP containing peptide.     

Differential regulation of leukemia inhibitory factor-stimulated neuronal gene expression by protein phosphatases SHP-1 and SHP-2 through mitogen-activated protein kinase-dependent and -independent pathways

The neurally active cytokine leukemia inhibitory factor (LIF) signals through a bipartite receptor complex composed of LIF receptor alpha (LIFR) and gp130. gp130 and LIFR contain consensus binding motifs for the protein tyrosine phosphatase SHP-2 surrounding tyrosines 118 and 115 (Y118 and Y115) of their cytoplasmic domains, respectively. These sites are necessary for maximal activation of mitogen-activated protein kinase (MAPK). Coexpression of catalytically inactive, but not wild-type, SHP-2 reduced LIFR- and gp130-mediated activation of MAPK up to 75%. Conversely, coexpression of the wild-type, but not catalytically inactive, SHP-1, a related phosphatase, reduced activity up to 80%, demonstrating that SHP-2 and SHP-1 have opposing effects on the MAPK pathway. Mutation of Y115 of the cytoplasmic domain of LIFR eliminates receptor-mediated tyrosine phosphorylation of SHP-2. In contrast, SHP-1 association with gp130 and LIFR is constitutive and independent of Y118 and Y115, respectively. SHP-1 has a positive regulatory role on LIF-stimulated vasoactive intestinal peptide (VIP) reporter gene expression in neuronal cells, whereas the effect of SHP-2 is negative. Furthermore, LIF-stimulated MAPK activation negatively regulates this VIP reporter gene induction. SHP-2 also negatively regulates LIF-dependent expression of choline acetyltransferase, but this regulation could be dissociated from its effects on MAPK activation. These data indicate that SHP-1 and SHP-2 are important regulators of LIF-dependent neuronal gene expression via both MAPK-dependent and -independent pathways.     

TIMP-1 inhibits apoptosis in breast carcinoma cells via a pathway involving pertussis toxin-sensitive G protein and c-Src

In addition to inhibiting matrix metalloproteinases, tissue inhibitor of metalloproteinase-1 (TIMP-1) is involved in the regulation of cell growth and survival. To determine its mechanism of action, we investigated effects of TIMP-1 on cell proliferation and survival and signaling pathways induced by TIMP-1 in the human breast carcinoma T-47D cell line. Treatment of T-47D cells with TIMP-1 strongly inhibited apoptosis induced by serum deprivation, but did not affect cell proliferation. TIMP-1 induced phosphorylation of Akt and extracellular signal-regulated protein kinases (ERKs), but pertussis toxin and specific inhibitors of Src family tyrosine kinases, protein tyrosine kinases, and phosphatidylinositol-3 kinase (PI3 kinase) blocked the ability of TIMP-1 to activate Akt and ERKs as well as the anti-apoptotic effect of TIMP-1. We found that TIMP-1 enhanced the kinase activities of c-Src and PI3 kinase and that this enhancement was inhibited by pertussis toxin. Inhibition of ERK activation, however, resulted in a slight decrease of the TIMP-1-induced anti-apoptotic effect. These findings demonstrate that the ability of TIMP-1 to inhibit apoptosis in T-47D cells is mediated by the sequential activation of pertussis toxin-sensitive G protein, c-Src, PI3 kinase, and Akt.     

Tyrosine phosphorylation and association of BIT with SHP-2 induced by neurotrophins

BIT (brain immunoglobulin-like molecule with tyrosine-based activation motifs) is a membrane glycoprotein that has two cytoplasmic TAMs (tyrosine-based activation motifs). We previously reported that tyrosine-phosphorylated TAMs of BIT interact with the Src homology 2 domain-containing protein tyrosine phosphatase SHP-2 both in vitro and in transfected cells, and this association results in a potent stimulation of the phosphatase activity of SHP-2. Both BIT and SHP-2 are highly expressed in the mammalian brain, and they may play important roles in the regulation of synaptic function. In this study, we found that nerve growth factor (NGF) treatment of PC12 cells leads to the tyrosine phosphorylation of BIT and a subsequent complex formation between BIT and SHP-2. Furthermore, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) also induced the tyrosine phosphorylation of BIT and the association with SHP-2 in primary cultured rat neurons. Our results suggest that the BIT-SHP-2 signaling pathway is a novel signal transduction mechanism of neurons that acts in response to neurotrophic factors such as NGF, BDNF, and NT-3.