关键词： Antioxidants   ERK   Gene Silencing   Nrf2   Scaffold Proteins   IQGAP1   MEK   PEITC  

摘要： Nrf2 plays a critical role in the regulation of cellular oxidative stress. MEK-ERK activation has been shown to be one of the major pathways resulting in the activation of Nrf2 and induction of Nrf2 downstream targets, including phase II detoxifying/antioxidant genes in response to oxidative stress and xenobiotics. In this study, IQGAP1 (IQ motif-containing GTPase-activating protein 1), a new Nrf2 interaction partner that we have published previously, was found to modulate MEK-ERK-mediated Nrf2 activation and induction of phase II detoxifying/antioxidant genes. Nrf2 binds directly to the IQ domain (amino acids 699-905) of IQGAP1. Knockdown of IQGAP1 significantly attenuated phenethyl isothiocyanate-or MEK-mediated activation of the MEK-ERK-Nrf2 pathway. Knockdown of IQGAP1 also attenuated MEK-mediated increased stability of Nrf2, which in turn was associated with a decrease in the nuclear translocation of Nrf2 and a decrease in the expression of phase II detoxifying/antioxidant genes. In the aggregate, these results suggest that IQGAP1 may play an important role in the MEK-ERK-Nrf2 signaling pathway.

关键词： 支架蛋白1   RNA干扰   慢病毒载体  

摘要： 目的制备携带人支架蛋白IQGAP1基因小分子干扰RNA的重组慢病毒。方法分别设计合成针对IQGAP1的4个shRNA慢病毒干扰载体;分别转染293T细胞,利用Western blot验证shRNA的沉默效果,选择其中一个沉默效果较好的shRNA慢病毒干扰载体同源重组产生Lentivirus-IQGAP1-shRNA并测定病毒滴度。结果测序证实,构建携带IQGAP1-shRNA的慢病毒载体具有较好的沉默靶基因的效果,包装慢病毒,病毒滴度为2.0×l010TU/ml。结论成功制备携带IQGAP1-shRNA的重组慢病毒载体并包装出具高效感染力的慢病毒颗粒。

关键词： Cancer   Diabetes   IQGAP1   Metabolism   Signaling  

摘要： Abstract: Epidemiology studies revealed the connection between several types of cancer and type 2 diabetes (T2D) and suggested that T2D is both a symptom and a risk factor of pancreatic cancer. High level of circulating insulin (hyperinsulinemia) in obesity has been implicated in promoting aggressive types of cancers. Insulin resistance, a symptom of T2D, pressures pancreatic β-cells to increase insulin secretion, leading to hyperinsulinemia, which in turn leads to a gradual loss of functional β-cell mass, thus indicating a fine balance and interplay between β-cell function and mass. While the mechanisms of these connections are unclear, the mTORC1-Akt signaling pathway has been implicated in controlling β-cell function and mass, and in mediating the link of cancer and T2D. However, incomplete understating of how the pathway is regulated and how it integrates body metabolism has hindered its efficacy as a clinical target. The IQ motif containing GTPase activating protein 1 (IQGAP1)-Exocyst axis is a growth factor- and nutrient-sensor that couples cell growth and division. Here we discuss how IQGAP1-Exocyst, through differential interactions with Rho-type of small guanosine triphosphatases (GTPases), acts as a rheostat that modulates the mTORC1-Akt and MAPK signals, and integrates β-cell function and mass with insulin signaling, thus providing a molecular mechanism for cancer initiation in diabetes. Delineating this regulatory pathway may have the potential of contributing to optimizing the efficacy and selectivity of future therapies for cancer and diabetes. [Copyright &y& Elsevier]

关键词： Cancer   Diabetes   Signaling   Metabolism   IQGAP1  

摘要： Epidemiology studies revealed the connection between several types of cancer and type 2 diabetes (T2D) and suggested that T2D is both a symptom and a risk factor of pancreatic cancer. High level of circulating insulin (hyperinsulinemia) in obesity has been implicated in promoting aggressive types of cancers. Insulin resistance, a symptom of T2D, pressures pancreatic beta-cells to increase insulin secretion, leading to hyperinsulinemia, which in turn leads to a gradual loss of functional beta-cell mass, thus indicating a fine balance and interplay between beta-cell function and mass. While the mechanisms of these connections are unclear, the mTORC1-Akt signaling pathway has been implicated in controlling beta-cell function and mass, and in mediating the link of cancer and T2D. However, incomplete understating of how the pathway is regulated and how it integrates body metabolism has hindered its efficacy as a clinical target The IQ motif containing GTPase activating protein 1 (IQGAP1)-Exocyst axis is a growth factor- and nutrient-sensor that couples cell growth and division. Here we discuss how IQGAP1-Exocyst, through differential interactions with Rho-type of small guanosine triphosphatases (GTPases), acts as a rheostat that modulates the mTORC1-Akt and MAPK signals, and integrates beta-cell function and mass with insulin signaling, thus providing a molecular mechanism for cancer initiation in diabetes. Delineating this regulatory pathway may have the potential of contributing to optimizing the efficacy and selectivity of future therapies for cancer and diabetes. Published by Elsevier B.V.

关键词： TRANSCRIPTION factors   GENE expression   OXIDATIVE stress   CELLULAR control mechanisms   PROTEIN-protein interactions   CELLULAR signal transduction  

摘要： Aims: Nuclear factor-erythroid-related factor 2 (Nrf2) is a critical transcriptional factor that is used in regulating cellular defense against oxidative stress. This study is aimed at investigating new interacting protein partners of Nrf2 using One-strep tag pull-down coupled with LTQ Orbitrap LC/MS/MS, and at examining the impact on Nr2 signaling by the newly identified IQ motif containing GTPase activating protein 1 (IQGAP1). Results: Using the One-strep tag pull-down and LTQ Orbitrap LC/MS/MS, we identified IQGAP1 as a new Nrf2 interacting partner. Direct interactions between IQGAP1 and Nrf2 proteins were verified using in vitro glutathione S-transferase (GST) pull-down, transcription/translation assays, and in vivo utilizing Nrf2 overexpressing cells. Coexpression of Dsredmono-IQGAP1 and eGFP-Nrf2 increased the stability of eGFP-Nrf2 and enhanced the expression of Nrf2-target gene heme oxygenase-1 (HO-1). To confirm the functional role of IQGAP1 on Nrf2, knock-downed IQGAP1 using siIQGAP1 attenuated the expression of endogenous Nrf2, HO-1 proteins, and Nrf2-target genes GSTpi, GCLC, and NAD(P) H: quinone oxidoreductase 1 (NQO-1). Furthermore, the stability of Nrf2 was dramatically decreased in IQGAP1-deficient mouse embryonic fibroblast (MEF) cells. Since IQGAP1 signaling could be mediated by calcium, treating the cells with calcium showed the translocation of IQGAP1/Nrf2 complex into the nucleus, suggesting that IQGAP1 may play a critical role in Nrf2 stability. Interestingly, consistent with calcium signaling for IQGAP1, treating the cells with calcium functionally enhanced Nrf2-mediated antioxidant responsive element-transcription activity and enhanced the expression of the endogenous Nrf2-target gene HO-1. Innovation: In the aggregate, our current study identifies and functionally characterizes a new Nrf2 partner protein IQGAP1, which may contribute to Nrf2's regulation of antioxidant enzymes such as HO-1. Conclusion: IQGAP1 may play a critical role in the

关键词： IQGAP1   Endothelial Adherens Junction   VE-cadherin   N-cadherin  

摘要： Adhesion molecules are known to play an important role in endothelial activation and angiogenesis. Here we determined the functional role of IQGAP1 in the regulation of endothelial adherens junctions. VE-cadherin is found to be associated with actin filaments and thus stable, but IQGAP1 at intercellular junctions is not bound to actin filaments and thus labile. Expression of GFP labeled VE-alpha-catenin is shown to increase the electrical resistance across HUVEC monolayers and diminishes endogenous labile IQGAP1 at the intercellular junctions. Knockdown of endogenous IQGAP1 enhances intercellular adhesion in HUVECs by increasing the association of VE-cadherin with P120 and beta-catenin. IQGAP1 knockdown also decreases the interaction of N-cadherin with P120 and beta-catenin. Together, these results suggest that a labile pool of IQGAP1 at intercellular junctions disassembles adherens junctions and thus impairs endothelial cell-cell adhesion.

关键词： glomerular   Angiotensin   activating   GTPase   saline   caspase   mesangial   infusion   assigned   capillary  

摘要： Objective To evaluate the effects of AngⅡon the expression of IQ domain GTPase-activating protein1(IQ-GAP1) and apoptosis of glomerular cells,and to explorethe role of IQGAP1in AngⅡ-induced apoptosis

关键词： SASH1   Mutation   Melanocyte migration   G alpha s   IQGAP1  

摘要： One important function of melanocytes (MCs) is to produce and transfer melanin to neighbouring keratinocytes (KCs) to protect epithelial cells from UV radiation. The mechanisms regulating the specific migration and localisation of the MC lineage remain unknown. We have found three heterozygous mutations that cause amino add substitutions in the SASH1 gene in individuals with a kind of dyschromatosis. In epidermal tissues from an affected individual, we observed the increased transepithelial migration of melanocytes. Functional analyses indicate that these SASH1 mutations not only cause the increased migration of A375 cells and but also induce intensive bindings with two novel cell adhesion partners IQGAP1 and G alpha s. Further, SASH1 mutations induce uniform loss of E-Cadherin in human A375 cells. Our findings suggest a new scaffold protein SASH1 to regulate IQGAP1-E-Cadherin signalling and demonstrate a novel crosstalking between GPCR signalling, calmodulin signalling for the modulation of MCs invasion. (C) 2013 Elsevier Inc. All rights reserved.

关键词： Squamous cell carcinoma  

摘要： Upregulation of the ERK1 and ERK2 (ERK1/2) MAP kinase (MAPK) cascade occurs in >30% of cancers(1), often through mutational activation of receptor tyrosine kinases or other upstream genes, including KRAS and BRAF(2). Efforts to target endogenous MAPKs are challenged by the fact that these kinases are required for viability in mammals(3) (,4). Additionally, the effectiveness of new inhibitors of mutant BRAF has been diminished by acquired tumor resistance through selection for BRAF-independent mechanisms of ERK1/2 induction(2,5,6). Furthermore, recently identified ERK1/2-inducing mutations in MEK1 and MEK2 (MEK1/2) MAPK genes in melanoma confer resistance to emerging therapeutic MEK inhibitors, underscoring the challenges facing direct kinase inhibition in cancer(7,8). MAPK scaffolds, such as IQ motif-containing GTPase activating protein 1 (IQGAP1)(9,10), assemble pathway kinases to affect signal transmission(11-13), and disrupting scaffold function therefore offers an orthogonal approach to MAPK cascade inhibition. Consistent with this, we found a requirement for IQGAP1 in RAS-driven tumorigenesis in mouse and human tissue. In addition, the ERK1/2-binding(14) IQGAP1 WW domain peptide disrupted IQGAP1-ERK1/2 interactions, inhibited RAS- and RAF-driven tumorigenesis, bypassed acquired resistance to the BRAF inhibitor vemurafenib (PLX-4032) and acted as a systemically deliverable therapeutic to significantly increase the lifespan of tumor-bearing mice. Scaffold-kinase interaction blockade acts by a mechanism distinct from direct kinase inhibition and may be a strategy to target overactive oncogenic kinase cascades in cancer.

摘要： Cell culture and mouse studies identified a peptide-based inhibitor of IQGAP1 that could help treat cancer.