关键词： Adaptor Proteins, Signal Transducing/metabolism   Carcinoma, Non-Small-Cell Lung/metabolism   Carcinoma, Non-Small-Cell Lung/pathology   Cell Nucleus/metabolism   Cytoplasm/metabolism   Female   Humans   Lung Neoplasms/metabolism   Lung Neoplasms/pathology   Lymphatic Metastasis   Male   Middle Aged   Phosphoproteins/metabolism   Prognosis   ras GTPase-Activating Proteins/metabolism   Survival Analysis   Wnt Signaling Pathway  

摘要： Background: IQ-domain GTPase-activating protein 1 (IQGAP1) binds to Dishevelled (Dvl) and functions as a modulator of Dvl nuclear localization in Xenopus embryos. However, the relationship between IQGAP1 and Dvl in tumor tissues is unclear. Materials and Methods: We used immunohistochemistry to assess the expressions of IQGAP1 and Dvl in a cohort of 111 non-small cell lung cancer (NSCLC) patients. Association of their localization expressions with clinicopathological factors was also analyzed. Results: The positive rate of IQGAP1 in primary tumors was 48.6% (54/111) for its cytoplamic expression, 9.0% (10/111) for nuclear expression and 31.5% (35/111) for membranous expression;the positive rate of Dvl was 65.8% (73/111) for cytoplamic expression, 9.9% (11/111) for nuclear expression and 10.8% (12/111) for membranous expression. Coexpression rate of IQGAP1 and Dvl was 77.8% (42/54) in the cytoplasm, 80.0% (8/10) in the nucleus and 8.6% (3/35) in the membrane. Coexpression of IQGAP1 and Dvl in the cytoplasm and nucleus were significantly correlated (P<0.05), but not in the membrane (P>0.05). The positive expression rates of cyclin D1 and c-myc were significantly higher in the group of IQGAP1 and Dvl coexpression in the nucleus than that in the cytoplasm. Coexpression rate of IQGAP1 and Dvl in the cytoplasm and nucleus was significantly higher in lymph nodal metastases (63.3%, 19/30) than in primary growths (38.3%, 31/81), correlating with poor prognosis. Five-year survival time after resection in the group with their coexpression in the cytoplasm and nucleus was significantly lower than that with no coexpression (44.705+/-3.355 vs 58.403+/-2.543 months, p<0.05). Conclusions: Coexpression of IQGAP1 and Dvl in the cytoplasm and nucleus was correlated with the lymph nodal metastase and poor prognosis of NSCLC, and coexpression in nucleus might play a critical role in the activation of canonical Wnt pathway.

关键词： ILK   Cell growth   IQGAP1   ERK1/2   NK-kappa B  

摘要： Background: Increased activity or expression of integrin-linked kinase (ILK), which regulates cell adhesion, migration, and proliferation, leads to oncogenesis. We identified the molecular basis for the regulation of ILK and its alternative role in conferring ERK1/2/NF-kappa B-mediated growth advantages to gastric cancer cells. Results: Inhibiting ILK with short hairpin RNA or T315, a putative ILK inhibitor, abolished NF-kappa B-mediated the growth in the human gastric cancer cells AGS, SNU-1, MKN45, and GES-1. ILK stimulated Ras activity to activate the c-Raf/MEK1/2/ ERK1/2/ribosomal S6 kinase/inhibitor of kappa Ba/NF-kappa B signaling by facilitating the formation of the IQ motif-containing GTPase-activating protein 1 (IQGAP1)-Ras complex. Forced enzymatic ILK expression promoted cell growth by facilitating ERK1/2/NF-kappa B signaling. PI3K activation or decreased PTEN expression prolonged ERK1/2 activation by protecting ILK from proteasome-mediated degradation. C-terminus of heat shock cognate 70 interacting protein, an HSP90-associated E3 ubiquitin ligase, mediated ILK ubiquitination to control PI3K- and HSP90-regulated ILK stabilization and signaling. In addition to cell growth, the identified pathway promoted cell migration and reduced the sensitivity of gastric cancer cells to the anticancer agents 5-fluorouracil and cisplatin. Additionally, exogenous administration of EGF as well as overexpression of EGFR triggered ILK- and IQGAP1-regulated ERK1/2/NF-kappa B activation, cell growth, and migration. Conclusion: An increase in ILK non-canonically promotes ERK1/2/NF-kappa B activation and leads to the growth of gastric cancer cells.

关键词： MUSCLE contraction   SMOOTH muscle   SCAFFOLD proteins   AIRWAY (Medicine)   MICE as laboratory animals   RESEARCH  

摘要： The intracellular scaffold protein IQGAP1 supports protein complexes in conjunction with numerous binding partners involved in multiple cellular professes. Here, we determined that IQGAP1 modulates airway smooth muscle contractility. Compared with WT controls, at baseline as well as after immune sensitization and challenge, Iqgap1(-/-) mice had higher airway responsiveness. Tracheal rings from Iqgap1(-/-) mice generated greater agonist-induced contractile force, even after removal of the epithelium. RhoA, a regulator of airway smooth muscle contractility, was activated in airway smooth muscle lysates from Iqgap1(-/-) mice. Likewise, knockdown of IQGAP1 in primary human airway smooth muscle cells increased RhoA activity. Immunoprecipitation studies indicated that IQGAP1 binds to both RhoA and p190A-RhoGAP, a GTPase-activating protein that normally inhibits RhoA activation. Proximity ligation assays in primary airway human smooth muscle cells and mouse tracheal sections revealed colocalization of p190A-RhoGAP and RhoA;however, these proteins did not colocalize in IQGAP1 knockdown cells or in Iqgap1(-/-) trachea. Compared with healthy controls, human subjects with asthma had decreased IQGAP1 expression in airway biopsies. Together, these data demonstrate that IQGAP1 acts as a scaffold that colocalizes p190A-RhoGAP and RhoA, inactivating RhoA and suppressing airway smooth muscle contraction. Furthermore, our results suggest that IQGAP1 has the potential to modulate airway contraction severity in acute asthma.

关键词： 肿瘤   支架蛋白IQGAP1   侵袭   综述文献  

摘要： 目的总结支架蛋白IQGAP1与肿瘤的研究进展,探讨其在恶性肿瘤迁移、侵袭和增殖方面的作用。方法应用PubMed和CNKI期刊全文数据库检索系统,以"支架蛋白1和肿瘤"为关键词,检索2000-01-2013-07相关文献,纳入标准:1)支架蛋白IQGAP1的特性和功能;2)支架蛋白IQGAP1在肿瘤组织中的表达;3)针对IQGAP1为靶点的肿瘤细胞相关实验研究。根据纳入标准,符合分析的文献35篇。结果 IQGAP1作为一种细胞骨架蛋白,在肿瘤细胞的运动和增殖等方面的作用引起越来越多的重视。首先IQGAP1可激活Rac1/CDC42信号通路,促使细胞形成侵袭性伪足;与肌动蛋白形成多聚体,引导细胞定向运动;减少正常细胞连接的E-cadherin复合体形成,降低细胞间的黏附力;加速细胞外基质(extracellular cell matrix,ECM)降解增强肿瘤细胞的侵袭能力。同时,IQGAP1还可激活MAPK/Raf/MEK/ERK信号传导通路,与β-catenin结合控制Wnt通路,后两者是促进细胞增殖的重要通路;与VEGF形成复合体,提高血管内皮细胞的运动和增殖能力,促进肿瘤血管的增生。IQGAP1在结肠癌、乳腺癌、肺癌、前列腺癌和卵巢癌等组织中表达明显增高,并与肿瘤复发、远处转移和患者生存时间密切相关;IQGAP1胞膜分布预示肿瘤的复发与分化,在侵袭性强、分化低的肿瘤IQGAP1更多分布于细胞外周;其通过改变上皮细胞的极性参与幽门螺杆菌导致胃肠道肿瘤的发病机制。结论支架蛋白IQGAP1在肿瘤细胞的运动、侵袭和增殖等生物学行为中发挥重要功能,在肿瘤组织中的表达和定位与肿瘤复发、转移和预后判断密切相关。IQGAP1在肿瘤的基础和临床研究中具有广阔的前景。

关键词： Binding Sites   Cognition   Cohort Studies   Evolution, Molecular   Evolution, Molecular   Female   Gene Frequency   Humans   Male   Memory   MicroRNAs/physiology   MicroRNAs/physiology   Polymorphism, Single Nucleotide   ras GTPase-Activating Proteins/chemistry   ras GTPase-Activating Proteins/genetics   Sex Factors   Wechsler Scales  

摘要： As a product of the unique evolution of the human brain, human cognitive performance is largely a collection of heritable traits. Rather surprisingly, to date there have been no reported cases to highlight genes that underwent adaptive evolution in humans and which carry polymorphisms that have a marked effect on cognitive performance. IQ motif containing GTPase activating protein 1 (IQGAP1), a scaffold protein, affects learning and memory in a dose-dependent manner. Its expression is regulated by miR-124 through the binding sites in the 3'UTR, where a SNP (rs1042538) exists in the core-binding motif. Here we showed that this SNP can influence the miR-target interaction both in vitro and in vivo. Individuals carrying the derived T alleles have higher IQGAP1 expression in the brain as compared to the ancestral A allele carriers. We observed a significant and male-specific association between rs1042538 and tactile performances in two independent cohorts. Males with the derived allele displayed higher tactual performances as compared to those with the ancestral allele. Furthermore, we found a highly diverged allele-frequency distribution of rs1042538 among world human populations, likely caused by natural selection and/or recent population expansion. These results suggest that current human populations still carry sequence variations that affect cognitive performances and that these genetic variants may likely have been subject to comparatively recent natural selection.

关键词： IQGAP1   同质粘附   基因干扰   食管癌  

摘要： 目的:研究IQGAP1基因干扰对人食管癌细胞同质粘附能力的影响。方法:体外培养人食管癌KYSE150和EC9706细胞,利用Western blot方法检测两株细胞。IQGAP1蛋白的表达,利用缓慢聚集和细胞分离实验比较两株细胞同质粘附能力的差异;进一步在KYSE150和EC9706细胞中构建IQGAP1基因干扰的稳定细胞系,观察IQGAP1基因干扰后细胞同质粘附能力的改变。结果:KYSE150细胞IQGAP1蛋白表达量低于EC9706细胞,而同质粘附能力高于EC9706细胞;IQGAP1基因干扰后,其蛋白表达量明显降低,而细胞同质粘附能力明显增强。结论:IQGAP1基因干扰能够显著增强食管癌细胞的同质粘附能力,从而降低肿瘤细胞的恶性表型。

关键词： DAB density shift   endothelial cell   fractionation   IQGAP1   LBRC   PECAM  

摘要： The migration of leukocytes across the endothelium and into tissue is critical to mounting an inflammatory response. The lateral border recycling compartment (LBRC), a complex vesicular-tubule invagination of the plasma membrane found at endothelial cell borders, plays an important role in this process. Although a few proteins have been shown to be present in the LBRC, no unique marker is known. Here, we detail methods that can be used to characterize a subcellular compartment that lacks an identifying marker. Initial characterization of the LBRC was performed using standard subcellular fractionation with sucrose gradients and took advantage of the observation that the compartment migrated at a lower density than other membrane compartments. To isolate larger quantities of the compartment, we modified a classic technique known as a diaminobenzidine (DAB)-induced density shift. The DAB-induced density shift allowed for specific isolation of membranes labeled with horseradish peroxidase-conjugated antibody. Because the LBRC could be differentially labeled at 4 degrees C and 37 degrees C, we were able to identify proteins that are enriched in the compartment, despite lacking a unique marker. These methods serve as a model to others studying poorly characterized compartments and organelles and are applicable to a wide variety of biological systems.

关键词： CROSS-talk (Biology)   RESEARCH   CYTOSKELETON   MICROTUBULES   SMALL interfering RNA   ACTIN -- Research   LIVER cells  

摘要： Cross talk between the actin cytoskeleton and microtubules (MT) has been implicated in the amplification of agonist-induced Rho signaling, leading to increased vascular endothelial permeability. This study tested the involvement of actin-MT cross talk in the mechanisms of barrier enhancement induced by hepatocyte growth factor (HGF) and evaluated the role of the adaptor protein IQGAP1 in integrating the MT- and actin-dependent pathways of barrier enhancement. IQGAP1 knockdown by small interfering RNA attenuated the HGF-induced increase in endothelial barrier properties and abolished HGF-activated cortical actin dynamics. IQGAP1 reduction abolished HGF-induced peripheral accumulation of Rac cytoskeletal effector cortactin and cortical actin remodeling. In addition, HGF stimulated peripheral MT growth in an IQGAP1-dependent fashion. HGF also induced Rac1-dependent IQGAP1 association with the MT fraction and the formation of a protein complex containing end-binding protein 1 (EB1), IQGAP1, and cortactin. Decreasing endogenous IQGAP1 abolished HGF-induced EB1-cortactin colocalization at the cell periphery. In turn, expression of IQGAP1 Delta C (IQGAP1 lacking the C-terminal domain) attenuated the cortactin association with EB1 and suppressed HGF-induced endothelial cell peripheral actin cytoskeleton enhancement. These results demonstrate for the first time the MT-actin cross talk mechanism of HGF-induced endothelial barrier enhancement and suggest that IQGAP1 functions as a hub linking HGF-induced signaling to MT and actin remodeling via EB1-IQGAP1-cortactin interactions.

关键词： RhoC   IQGAP1   肿瘤  

摘要： 肿瘤的发生和发展是一个长期的、分阶段的、多种基因突变积累的复杂过程，是由多个激活的原癌基因、失活的抑癌基因、变化的有关融合基因，以及一系列信号转导通路参与完成的。其中任何一个因素的改变都可以引起细胞增殖和凋亡失去控制从而导致肿瘤的发生。癌细胞的无限增殖和转移是最重要的肿瘤恶性生物学行为，且血管、淋巴管形成是癌细胞增殖和转移的基础，大多数癌症患者死于肿瘤的复发和转移，导致死亡的原因主要是肿瘤转移直接侵犯器官，副肿瘤综合征，和或治疗引起的并发症，因此明确肿瘤的复发，尤其是转移机制，可以为肿瘤的预防和治疗提供一些新的思考方向和治疗策略。

关键词： PAK6   IQGAP   Cell junctions   Cell motility   HGF  

摘要： p-21 activated 6 (PAK6), first identified as interacting with the androgen receptor (AR), is over-expressed in multiple cancer tissues and has been linked to the progression of prostate cancer, however little is known about PAK6 function in the absence of AR signaling. We report here that PAK6 is specifically required for carcinoma cell-cell dissociation downstream of hepatocyte growth factor (HGF) for both DU145 prostate cancer and HT29 colon cancer cells. Moreover, PAK6 overexpression can drive cells to escape from adhesive colonies in the absence of stimulation. We have localized PAK6 to cell-cell junctions and have detected a direct interaction between the kinase domain of PAK6 and the junctional protein IQGAP1. Co-expression of IQGAP1 and PAK6 increases cell colony escape and leads to elevated PAK6 activation. Further studies have identified a PAK6/E-cadherin/IQGAP1 complex downstream of HGF. Moreover, we find that beta-catenin is also localized with PAK6 in cell-cell junctions and is a novel PAK6 substrate. We propose a unique role for PAK6, independent of AR signaling, where PAK6 drives junction disassembly during HGF-driven cell-cell dissociation via an IQGAP1/E-cadherin complex that leads to the phosphorylation of beta-catenin and the disruption of cell-cell adhesions.