关键词： IQGAP1   脓毒症   呼吸窘迫综合征,急性   IQGAP1  

摘要： 脓毒症是临床危重病患者死亡的重要原因之一.肺脏是脓毒症时最易受损的靶器官,脓毒症患者常并发急性呼吸窘迫综合征（ARDS）,其主要机制是细胞骨架重排、细胞-细胞间连接改变,最终导致血管渗漏.IQ模序的三磷酸鸟苷酶活化蛋白1（IQGAP1）是近年来发现的细胞骨架动力学调节的关键组成部分.目前,IQGAP1与脓毒症相关ARDS的关系尚不完全清楚,本文在分子水平上对IQGAP1与病原微生物的相互作用机制、肺微血管屏障功能及细胞骨架的变化等研究进行综述.

关键词： 化疗敏感度   具有IQ结构域的GTP激酶活化蛋白1   食管鳞癌   小干扰RNA   转录因子E2相关因子2  

摘要： 目的研究具有IQ结构域的GTP激酶活化蛋白1基因(IQGAP1)对食管癌细胞KYSE150化疗敏感度的影响及其相关作用机制。方法构建针对IQGAP1基因的小干扰RNA(si RNA)并转染至食管鳞癌细胞株KYSE150,采用MTT法观察KYSE150细胞对化疗药物顺铂敏感度的改变;流式细胞技术检测IQGAP1基因沉默前后顺铂对KYSE150细胞周期分布及凋亡的影响;Western blot检测细胞转染前后转录因子E2相关因子2(nuclear factor erythroid-2 related factor 2,Nrf2)和多药耐药相关蛋白1(MRP1)的表达水平变化。结果转染si RNA可显著下调KYSE150细胞中的IQGAP1 m RNA和蛋白表达水平;经(1、5、10、20)μmol/L顺铂处理细胞24 h后,干扰组(IQGAP1-si RNA)的细胞生存率均较对照组发生明显下降(P<0.05);流式细胞仪检测结果显示干扰组在顺铂处理后G_0/G_1期细胞比例和凋亡率均明显高于对照组(P<0.05);Western blot结果显示IQGAP1基因沉默后,Nrf2和MRP1蛋白表达下调。结论沉默IQGAP1基因可有效提高人食管鳞癌细胞株KYSE150对顺铂的化疗敏感度,该作用可能是通过下调Nrf2和MRP-1蛋白表达来实现的。

关键词： 乳腺肿瘤   基因表达调控   钙黏着糖蛋白类   SASH1蛋白   含IQ模序的GTP酶活化蛋白1  

摘要： 目的:探讨SASH1(SAM-and SH3-domain containing 1)基因作为一个新的抑癌基因,在调节乳腺癌转移过程中的分子作用机制。方法:免疫组织化学法检测人乳腺癌组织中SASH1、含IQ模序的GTP酶活化蛋白1(IQ motif-containing GTPase activating protein 1,IQGAP1)和E-钙黏蛋白(E-cadherin)的表达水平,并分析三者之间的相关性,以及SASH1和IQGAP1表达与乳腺癌患者临床指标的相关性。构建重组质粒HA-IQGAP1-pcDNA3.0和pEGFP-C3-SASH1,并将其转染人胚胎肾细胞HEK-293T,然后采用免疫沉淀-蛋白质印迹法分析SASH1与IQGAP1的相互作用。结果:人乳腺癌组织中,SASH1与IQGAP1的表达存在相关性(P<0.05),而且二者分别与E-cadherin的表达明显相关(P值均<0.001);另外,SASH1和IQGAP1蛋白表达分别与乳腺癌的肿瘤直径和肿瘤分级有相关性(P值均<0.05),但与淋巴结转移无相关性(P值均>0.05)。成功构建重组质粒HA-IQGAP1-pcDNA3.0和pEGFP-C3-SASH1;重组质粒转染HEK-293T细胞后,发现SASH1与IQGAP1之间存在蛋白-蛋白相互作用。结论:SASH1与IQGAP1结合后可发生蛋白-蛋白相互作用,并且与E-cadherin的表达密切相关。推测SASH1可能与IQGAP1和E-cadherin形成一条新的调节乳腺癌转移的信号轴。

关键词： Chlamydia pneumoniae   Angiogenesis   Vascular endothelial cell   IQ domain GTPase-activating protein 1   Neural Wiskott-Aldrich syndrome protein  

摘要： Chlamydia pneumoniae (C. pneumoniae) infection plays a potential role in angiogenesis. However, it is still an enigma how C. pneumoniae is involved in this process. Therefore, we investigated the effect of C. pneumoniae infection on angiogenesis, and then explored the roles of IQGAPI-related signaling in C. pneumoniae infection-induced angiogenesis. C. pneumoniae infection significantly enhanced angiogenesis as assessed by the tube formation assay possibly by inducing vascular endothelial cell (VEC) migration in the wound healing and Transwell migration assays. Subsequently, immunoprecipitation, Western blot and tube formation assay results showed that the phosphorylation of both IQGAPI and N-WASP was required for the angiogenesis induced by C. pneumoniae infection. Our co-immunoprecipitation study revealed that IQGAP1 physically associated with N-WASP after C. pneumoniae infection of VECs. Actin polymerization assay further showed that in C pneumoniae-infected VECs, both IQGAPI and N-WASP were recruited to filamentous actin, and shared some common compartments localized at the leading edge of lamellipodia, which was impaired after the depletion of IQGAPI by using the small interference RNA. Moreover, the knockdown of IQGAP1 also significantly decreased N-WASP phosphorylation at Tyr256 induced by C pneumoniae infection. We conclude that C pneumoniae infection promotes VEC migration and angiogenesis presumably through the IQGAP1-related signaling pathway. (C) 2017 Elsevier GmbH. All rights reserved.

关键词： cancer   cell signaling   extracellular-signal-regulated kinase (ERK)   mitogen-activated protein kinase (MAPK)   protein complex   protein kinase   protein-protein interaction   scaffold protein   IQGAP1  

摘要： Mitogen-activated protein kinase (MAPK) scaffold proteins, such as IQ motif containing GTPase activating protein 1 (IQGAP1), are promising targets for novel therapies against cancer and other diseases. Such approaches require accurate information about which domains on the scaffold protein bind to the kinases in the MAPK cascade. Results from previous studies have suggested that the WW domain of IQGAP1 binds to the cancer-associated MAPKs ERK1 and ERK2, and that this domain might thus offer a new tool to selectively inhibit MAPK activation in cancer cells. The goal of this work was therefore to critically evaluate which IQGAP1 domains bind to ERK1/2. Here, using quantitative in vitro binding assays, we show that the IQ domain of IQGAP1 is both necessary and sufficient for binding to ERK1 and ERK2, as well as to the MAPK kinases MEK1 and MEK2. Furthermore, we show that the WW domain is not required for ERK-IQGAP1 binding, and contributes little or no binding energy to this interaction, challenging previous models of how WW-based peptides might inhibit tumorigenesis. Finally, we show that the ERK2-IQGAP1 interaction does not require ERK2 phosphorylation or catalytic activity and does not involve known docking recruitment sites on ERK2, and we obtain an estimate of the dissociation constant (K-d) for this interaction of 8 m. These results prompt a re-evaluation of published findings and a refined model of IQGAP scaffolding.

关键词： Bioengineering   Biological cultures   Biology and life sciences   Biotechnology   Cancers and neoplasms   Cell biology   Cell cultures   Cell signaling   CRISPR   Cultured tumor cells   Engineering and technology   Gene expression and vector techniques   Genome engineering   Histochemistry and cytochemistry techniques   Immunoblotting   Immunohistochemistry techniques   Immunologic techniques   MAPK signaling cascades   Medicine and health sciences   Melanoma cells   Melanomas   Molecular biology   Molecular biology assays and analysis techniques   Molecular biology techniques   Molecular probe techniques   Oncogenic signaling   Oncology   Protein expression   Research and analysis methods   Research Article   Signal transduction   Signaling cascades   Synthetic bioengineering   Synthetic biology   Synthetic genome editing   Synthetic genomics  

摘要： Canine oral mucosal melanoma is an aggressive malignant neoplasm and is characterized by local infiltration and a high metastatic potential. The disease progression is similar to that of human oral melanomas. Whereas human cutaneous melanoma is primarily driven by activating mutations in Braf (60%) or Nras (20%), human mucosal melanoma harbors these mutations much less frequently. This makes therapeutic targeting and research modeling of the oral form potentially different from that of the cutaneous form in humans. Similarly, research has found only rare Nras mutations and no activating Braf mutations in canine oral melanomas, but they are still reliant on MAPK signaling. IQGAP1 is a signaling scaffold that regulates oncogenic ERK1/2 MAPK signaling in human Ras- and Raf-driven cancers, including melanomas. To investigate whether IQGAP1 is a potential target in canine melanoma, we examined the expression and localization of IQGAP1 in primary canine melanomas and canine oral melanoma cell lines obtained from the University of California-Davis. Using CRISPR/Cas9 knockout of IQGAP1, we examined effects on downstream ERK1/2 pathway activity and assayed proliferation of cell lines when treated with a peptide that blocks the interaction between IQGAP1 and ERK1/2. We observed that canine IQGAP1 is expressed and localizes to a similar extent in both human and canine melanoma by qPCR, Western blot, and immunofluorescence. Deletion of IQGAP1 reduces MAPK pathway activation in cell lines, similar to effects seen in human Braf (V600E) cell lines. Additionally, we demonstrated reduced proliferation when these cells are treated with a blocking peptide in vitro.

关键词： CANCER   PROTEIN kinase B   NEUROLOGY   MOLECULES   SUBSTRATES (Biochemistry)  

摘要： ERK signaling and Akt signaling are inversely correlated in some cancers. Yet, the precise molecular mechanism for cross-inhibition remains unclear. In this issue of The EMBO Journal, Pan et al (2017) show that when Akt is on, its phosphorylated cytoplasmic substrate FOXO1 turns off ERK activity by reshaping the Ras-ERK scaffold IQGAP1.

关键词： FOXO1   AKT   MAPK   chemoresistance   cancer  

摘要： Nuclear FOXO proteins act as tumor suppressors by transcriptionally activating genes involved in apoptosis and cell cycle arrest, and these anticancer functions are inhibited by AKT-induced phosphorylation and cytoplasmic sequestration of FOXOs. We found that, after AKT-mediated phosphorylation at serine 319, FOXO1 binds to IQGAP1, a hub for activation of the MAPK pathway, and impedes IQGAP1-dependent phosphorylation of ERK1/2 (pERK1/2). Conversely, decreased FOXO1 expression increases pERK1/2 in cancer cell lines and correlates with increased pERK1/2 levels in patient specimens and disease progression. Treatment of cancer cells with PI3K inhibitors or taxane causes FOXO1 localization in the nucleus, increased expression of pERK1/2, and drug resistance. These effects are reversed by administering a small FOXO1-derived phospho-mimicking peptide inhibitor in vitro and in mice. Our results show a tumor suppressor role of AKT-phosphorylated FOXO1 in the cytoplasm and suggest that this function of FOXO1 can be harnessed to overcome chemoresistance in cancer.

关键词： colorectal cancer   scaffold proteins   AmotL2   FKBP51   IQGAP1   metastasized liver   FOLFOX   oxaliplatin   pericytes   telocytes  

摘要： Scaffold proteins play pivotal roles in the regulation of signaling pathways, integrating external and internal stimuli to various cellular outputs. We report the pattern of cellular and subcellular expression of scaffoldins angiomotin-like 2 (AmotL2), FK506 binding protein 5 (FKBP51) and IQ motif containing GTPase-activating protein 1 (IQGAP1) in colorectal cancer (CRC) and metastases in liver resected after oxaliplatin-based chemotherapy (CT). Positive immunostaining for the three scaffoldins was found in most cells in healthy colon, tumor, healthy liver and metastasized liver. The patterns of expression of AmotL2, FKBP51 and IQGAP1 show the greatest variability in immune system cells and neurons and glia cells and the least in blood vessel cells. The simultaneous subcellular localization in tumor cells and other cell types within the tumor suggest an involvement of these three scaffoldins in cancer biology, including a role in Epithelial Mesenchymal Transition. The display in differential localization and quantitative expression of AmotL2, FKBP51, and IQGAP1 could be used as biomarkers for more accurate tumor staging and as potential targets for anti-cancer therapeutics by blocking or slowing down their interconnecting functions. Tough further research needs to be done in order to improve these assessments.