关键词： IQGAP1   Nucleus   MAP kinase pathway   Podocytes   Slit diaphragm proteins  

摘要： IQGAP1, a protein that links the actin cytoskeleton to slit diaphragm proteins, is involved in podocyte motility and permeability. Its regulation in glomerular disease is not known. We have exposed human podocytes to puromycin aminonucleoside (PAN), an inducer of nephrotic syndrome in rats, and studied the effects on IQGAP1 biology and function. In human podocytes exposed to PAN, a nuclear translocation of IQGAP1 was observed by immunocytolocalization and confirmed by Western blot after selective nuclear/cytoplasmic extraction. In contrast to IQGAP1, IQGAP2 expression remained cytoplasmic. IQGAP1 nuclear translocation was associated with a significant decrease in its interaction with nephrin and podocalyxin. Activation of the ERK pathway was observed in PAN treated podocytes with a preponderant nuclear localization of the phosphorylated form of ERK (P-ERK). The interaction between IQGAP1 and P-ERK increased upon podocyte exposure to PAN. Inhibitors of ERK pathway activation blocked IQGAP1 nuclear translocation (p < 0.02). Chromatin interaction protein assays demonstrated an interaction of IQGAP1 with chromatin and with Histone H3, which increased in response to PAN. In summary, PAN induces the ERK dependent translocation of IQGAP1 into the nuclei in human podocytes which leads to the interaction of IQGAP1 with chromatin and Histone H3, and decreased interactions between IQGAP1 and slit-diaphragm proteins. Therefore, IQGAP1 may have a role in podocyte gene regulation in glomerular disease. (C) 2016 Elsevier Inc. All rights reserved.

关键词： IQGAP1   RAS   siRNA   Apoptosis   HepG2 cells  

摘要： IQ motif-containing GTPase-activating proteins (IQGAPs) belong to a conserved family, and they are involved in various intracellular processes. IQGAP1 is expressed in all cells, while IQGAP2 and IQGAP3 are mainly expressed in hepatic cells. IQGAP1 has been suggested to be an oncogene, while IQGAP2 is considered a tumor-suppressor gene. However, the relationship between RAS family genes and IQGAP genes remains unclear. We recently demonstrated this interaction in a chemically induced mouse liver cancer. In this study, IQGAP1 expression was partially silenced in human hepatocellular carcinoma (HepG2) cells. We investigated the impact of IQGAP1 silencing on the interactions of IQGAP and RAS with several apoptotic proteins, including caspase-3 (CASP3), BCL2-associated X protein (BAX), and B-cell leukemia/lymphoma 2 (BCL2). Additionally, we investigated the effects of the interactions of these genes on cell viability, proliferation, apoptosis, and invasive capacity. IQGAP1 siRNA-treated HepG2 cells showed lower invasive capacity than the control cells, and this reduction was time- and vector concentration-dependent. In addition, IQGAP1 silencing resulted in significantly lower IQGAP1 level and subsequently higher IQGAP2 and IQGAP3 expression in HepG2 cells than in the control. Flow cytometry analyses indicated that the silencing of IQGAP1 can induce early and late apoptosis in HepG2 cells. Additionally, IQGAP2, IQGAP3, CASP3, and BAX were upregulated whereas IQGAP1 and BCL2 were downregulated in the siRNA-treated cells. Furthermore, we observed that the mRNA levels of HRAS, KRAS, NRAS, and MRAS decreased upon IQGAP1 silencing. These findings indicate that IQGAP1 potentially regulates the expression of IQGAP and RAS gene families and demonstrate its regulatory role in the apoptotic network. Taken together, our findings suggest that IQGAP1 silencing plays crucial roles in the apoptosis of HepG2 cells and lowers their proliferative and invasive capacities.

关键词： MALAT1   IQGAP1   Proliferation   Invasion   Thyroid cancer  

摘要： Background: Increasing evidence indicated that metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acted as a key regulator in the proliferation and invasion of several cancers. However, the function of MALAT1 in the development of thyroid cancer has not been experimentally established. Methods: The expression of MALAT1 and IQGAP1 in thyroid cancer tissues and cells were detected by quantitative real-time PCR and western blot. The effects of MALAT1 and IQGAP1 on the cell proliferation and invasion of thyroid cancer cells were detected with a 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium 4 (MTT) assay and a Transwell assay, respectively. FTC-133 or SW1736 transfected with siMALAT1 or pcDNA-MALAT1 were injected subcutaneously into 4-week-olds BALB/c mice to examine the impact of MALAT1 on the tumor development of thyroid cancer in vivo. Results: In this study, we discovered the higher level of MALAT-1 and expression of IQGAP1 in thyroid cancer tissues and in thyroid cancer cells compared to that in the control. MTT and Transwell assay showed that the proliferation and invasion of FTC-133 cells with MALAT-1 knockdown were inhibited. Moreover, MALAT-1 could upregulate the expression of IQGAP1 in thyroid cancer cells. In addition, IQGAP1 knockdown reversed the decreasing cell proliferation and invasion of thyroid cancer induced by MALAT-1 overexpression. Finally, the study in vivo verified that MALAT-1 promoted the tumor growth of thyroid cancer. Conclusion: Our study indicated that MALAT1 promoted the proliferation and invasion of thyroid cancer cells via regulating the expression of IQGAP1. (C) 2016 Elsevier Masson SAS. All rights reserved.

关键词： cell signaling   Hippo pathway   protein complex   transcription factor   yes-associated protein (YAP)   IQGAP1  

摘要： During development, the Hippo signaling pathway regulates key physiological processes, such as control of organ size, regeneration, and stem cell biology. Yes-associated protein (YAP) is a major transcriptional co-activator of the Hippo pathway. The scaffold protein IQGAP1 interacts with more than 100 binding partners to integrate diverse signaling pathways. In this study, we report that IQGAP1 binds to YAP and modulates its activity. IQGAP1 and YAP co-immunoprecipitated from cells. In vitro analysis with pure proteins demonstrated a direct interaction between IQGAP1 and YAP. Analysis with multiple fragments of each protein showed that the interaction occurs via the IQ domain of IQGAP1 and the TEAD-binding domain of YAP. The interaction between IQGAP1 and YAP has functional effects. Knock-out of endogenous IQGAP1 significantly increased the formation of nuclear YAP-TEAD complexes. Transcription assays were performed with IQGAP1-null mouse embryonic fibroblasts and HEK293 cells with IQGAP1 knockdown by CRISPR/Cas9. Quantification demonstrated that YAP-TEAD-mediated transcription in cells lacking IQGAP1 was significantly greater than in control cells. These data reveal that IQGAP1 binds to YAP and modulates its co-transcriptional function, suggesting that IQGAP1 participates in Hippo signaling.

关键词： IQGAP1   肿瘤   Meta分析  

摘要： [目的]应用Meta分析探讨IQGAP1基因的表达与肿瘤分化程度、淋巴结转移情况和临床分期的相关性。[方法]在中国知网（CNKI）、中国生物医学文献数据库（CBM）、万方医学网、维普、Medline及PubMed等数据库中,中文以＂IQGAP1,肿瘤或癌症＂、英文以＂IQGAP1,tumor或cancer＂为检索词,检索建库至今已发表的中英文文献资料和学位论文,根据纳入排除标准筛选文献,采用RevMan5.2和Stata13.0软件分析纳入文献资料中IQGAP1蛋白的表达与肿瘤分化程度、淋巴结转移、临床分期的相关性。[结果]（1）IQGAP1在中低分化组及高分化组肿瘤组织中表达的比较：合并OR值为1.85,95%CI：1.23-2.80,P=0.003;（2）IQGAP1在有无淋巴结转移的肿瘤组织中表达的比较：合并OR值为1.57,95%CI：1.06-2.32,P=0.02;（3）IQGAP1在临床分期为Ⅰ-Ⅱ期和Ⅲ-Ⅳ期肿瘤组织中表达的比较：合并OR值为3.40,95%CI：2.27-5.10,P〈0.0001。[结论 ]IQGAP1蛋白的表达与肿瘤分化程度、临床分期及淋巴结转移密切相关。IQGAP1可以作为临床评估肿瘤恶性程度的重要指标。

关键词： 非小细胞肺癌   IQGAP1   ERK   信号通路   细胞增殖  

摘要： 该研究探讨了IQGAP1(IQ domain GTPase-activating protein 1)对非小细胞肺癌(nonsmall cell lung cancer,NSCLC)细胞增殖的影响及其对ERK信号通路的调节作用。将内源性IQGAP1低表达的A549细胞中分为空白组、空载组和IQGAP1过表达组;将内源性IQGAP1高表达的H1299细胞中分为空白组、阴性对照si RNA组和IQGAP1 si RNA组;采用ERK1/2磷酸化抑制剂U0126处理上述两株细胞。MTT法检测细胞增殖能力,Western blot法检测ERK1/2和p-ERK1/2蛋白质水平。结果显示,在A549细胞中,过表达IQGAP1能促进细胞增殖并促进ERK1/2磷酸化;在H1299中,敲低IQGAP1表达能够抑制细胞增殖并下调ERK1/2磷酸化水平。用U0126处理后能抑制IQGAP1对细胞增殖的促进作用。研究结果表明,IQGAP1可通过ERK信号通路促进体外非小细胞肺癌细胞增殖。

关键词： Allele specific expression   eQTL   Multiple sclerosis   CD69   IKZF3   IQGAP1  

摘要： Background: Multiple sclerosis is a chronic inflammatory, demyelinating disease of the central nervous system. Recent genome-wide studies have revealed more than 110 single nucleotide polymorphisms as associated with susceptibility to multiple sclerosis, but their functional contribution to disease development is mostly unknown. Results: Consistent allelic imbalance was observed for rs907091 in IKZF3 and rs11609 in IQGAP1, which are in strong linkage disequilibrium with the multiple sclerosis associated single nucleotide polymorphisms rs12946510 and rs8042861, respectively. Using multiple sclerosis patients and healthy controls heterozygous for rs907091 and rs11609, we showed that the multiple sclerosis risk alleles at IKZF3 and IQGAP1 are expressed at higher levels as compared to the protective allele. Furthermore, individuals homozygous for the multiple sclerosis risk allele at IQGAP1 had a significantly higher total expression of IQGAP1 compared to individuals homozygous for the protective allele. Conclusions: Our data indicate a possible regulatory role for the multiple sclerosis-associated IKZF3 and IQGAP1 variants. We suggest that such cis-acting mechanisms may contribute to the multiple sclerosis association of single nucleotide polymorphisms at IKZF3 and IQGAP1.

关键词： Cell signaling   IQGAP   Phosphatidylinositol phosphate kinase   Phosphoinositide  

摘要： Phosphatidylinositol 4,5-bisphosphate (PI4,5P₂) is a lipid messenger that regulates a wide variety of cellular functions. The majority of cellular PI4,5P₂ is generated by isoforms of the type I phosphatidylinositol phosphate kinases (PIPKI) that are generated from three genes, and each PIPKI isoform has a unique distribution and function in cells. It has been shown that the signaling specificity of PI4,5P₂ can be determined by a physical association of PIPKs with PI4,5P₂ effectors. IQGAP1 is newly identified as an interactor of multiple isoforms of PIPKs. Considering the versatile roles of IQGAP1 in cellular signaling pathways, IQGAP1 may confer isoform-specific roles of PIPKs in distinct cellular locations. In this mini review, the emerging roles of PIPKs that are regulated by an association with IQGAP1 will be summarized. Focuses will be on cell migration, vesicle trafficking, cell signaling, and nuclear events. © 2015 Elsevier Ltd.

关键词： microRNA-506   乳腺癌   含IQ模序的GTP1酶活化蛋白(IQGAP1)   ERK信号通路  

摘要： 乳腺癌是人类最常见的一类恶性肿瘤,发病率高居妇女癌症第二位。Micro RNA-506(mi R506)与多种肿瘤的发生发展密切相关,且在肿瘤组织中表达异常。然而,mi RNA-506调节乳腺癌发生发展的作用机制目前尚不清楚。在多种肿瘤组织和肿瘤细胞中含IQ模序的GTP1酶活化蛋白(IQGAP1)表达上调,发挥致癌作用。因此,我们推测mi RNA-506在乳腺癌中发挥抑癌作用,且其下游靶基因为IQGAP1。本研究以mi RNA-506为切入点,为进一步探讨mi RNA-506调节乳腺癌发生发展的作用机制,为开发更有效的乳腺癌治疗靶点和方法奠定理论基础。在本研究中,我们首先采用RT-q PCR法检测mi RNA-506在恶性乳腺组织以及乳腺癌细胞系中的表达,结果显示在人乳腺组织及乳腺癌细胞系中,mi R-506表达量显著下降,且随着肿瘤分期增加,呈现逐渐减少的趋势。功能性实验结果显示,mi R-506低表达的MDA-MB-231细胞的增殖、侵袭以及粘附能力显著增加,而过表达mi R-506的HCC1937细胞的增殖、侵袭以及粘附能力显著下降,提示mi R-506在乳腺癌中发挥抑癌作用。接下来,我们检测到在人乳腺组织及乳腺癌细胞系中,IQGAP1蛋白表达显著上调,且随着肿瘤分期增加,表达逐渐增高,提示IQGAP1在乳腺癌中发挥促癌作用。荧光素酶实验证实mi R-506通过3’UTR端靶向作用于IQGAP1并下调IQGAP1表达,提示IQGAP1为mi R-506的下游靶基因。进一步的研究指出IQGAP1可以中和mi R-506所诱导的肿瘤细胞的增殖侵袭以及粘附能力。为进一步探讨mi R-506在乳腺癌中的作用机制,我们对相关的信号通路分子进行了检测,研究结果表明,mi R-506能够下调Erk1/2磷酸化,且IQGAP1可缓解mi R-506的这种作用。本研究首次证实mi R-506在乳腺癌细胞中能够作为一种肿瘤抑制因子,可直接下调IQGAP1的表达,进而抑制ERK信号通路发挥抑癌作用。本研究为将mi R-506/IQGAP1/ERK通路作为成为新的乳腺癌治疗靶点提供理论依据。

关键词： HBx   CDC42   IQGAP1   细胞恶性转化   定量蛋白质组学  

摘要： 肝细胞癌是世界第五大流行癌症,致死率非常高。慢性乙型肝炎病毒(Hepatitis B virus, HBV)感染被认为是诱发肝癌的主要因素。研究发现HBV基因组x基因编码的X蛋白(hepatitsis B virus X protein, HBx)在HBV复制和诱发肝癌过程中具有重要作用。课题组前期对HBx转基因小鼠SILAC (Stable Isotope Labeling with Amino acids in Cell culture)定量蛋白质组学研究发现,在HBx诱发小鼠肝脏由重度炎症转变为癌症过程中,CDC42信号通路相关分子及CDC42蛋白本身蛋白表达量上调,提示在HBx诱发小鼠肝癌过程中,CDC42信号通路被激活。激活的CDC42可参与多条信号通路,引起细胞骨架、细胞周期、细胞侵袭转移能力等改变。为了解CDC42蛋白是否参与以及如何参与HBx介导的Huh7细胞恶性转化,本研究首先通过CRISPR/Cas9技术对Huh7-HBx细胞中的CDC42基因进行修饰,而后通过添加CDC42特异性抑制剂CASIN抑制Huh7-mock细胞和Huh7-HBx细胞中CDC42活性,探究CDC42功能破坏时HBx介导的Huh7恶性转化程度变化,进而揭示CDC42在HBx诱发人肝细胞恶性转化中的作用。研究结果将为深入理解HBV致癌机制、寻找HBV相关肝癌的治疗靶标提供理论依据。具体研究结果如下：***介导Huh7细胞恶性转化为了解HBx基因的异常表达是否可引起人肝癌细胞系Huh7细胞系的恶性转化,首先应用实时定量PCR检测Huh7-mock细胞和Huh7-HBx细胞中HBx基因表达情况,采用CCK-8试剂盒检测2种细胞的增殖能力、Annex V和FITC试剂盒检测细胞凋亡水平,并通过细胞划痕实验检测HBx基因转染前后Huh7细胞迁移能力的变化情况。结果显示：(1)Huh7-HBx细胞中HBx基因的表达显著高于Huh7-mock细胞(p<0.01)；(2)Huh7-HBx细胞的增殖能力显著高于Huh7-mock细胞(p<0.01)；(3)Huh7-HBx细胞的抗凋亡能力显著高于Huh7-mock细胞(流式细胞仪分析)。(4)Huh7-HBx细胞的迁移能力高于Huh7-mock细胞；(5)与Huh7-mock细胞相目比,Huh7-HBx细胞中CDC42蛋白表达量升高(Western blot分析)。***介导Huh7细胞恶性转化依赖CDC42为了验证CDC42蛋白是否参与HBx介导的Huh7细胞恶性转化,首先应用CRISPR/Cas9系统对Huh7-HBx细胞中CDC42基因进行编辑,检测CDC42基因敲除前后细胞的增殖能力、凋亡水平及迁移能力,而后采用CDC42蛋白特异性抑制剂CASIN处理Huh7-mock细胞和Huh7-HBx细胞,了解其对细胞增殖及凋亡水平的影响。结果发现：(1)获得在CDC42基因第二外显子处具有4个碱基缺失的突变体细胞(Huh7-HBx CDC42 KO);(2)Huh7-HBx CDC42 KO细胞增殖能力显著低于Huh7-HBx细胞(p<0.01)；(3)Huh7-HBx CDC42 KO细胞群体中晚期凋亡细胞比例升高,即细胞抗凋亡能力显著下降；(4)Huh7-HBx CDC42 KO细胞的迁移能力低于Huh7-HBx细胞；(5)不同浓度CASIN处理一定时间后,Huh7-HBx细胞的增殖能力显著降低(p<0.01),而Huh7细胞的增殖能力没有显著变化；Huh7-HBx细胞的抗凋亡能力显著下降(p