Small GTPases最新文献

{"title":"Approaches to inhibiting oncogenic K-Ras.","authors":"Alemayehu A Gorfe, Kwang-Jin Cho","doi":"10.1080/21541248.2019.1655883","DOIUrl":"10.1080/21541248.2019.1655883","url":null,"abstract":"<p><p>Activating somatic K-Ras mutations are associated with >15% all human tumors and up to 90% of specific tumor types such as pancreatic cancer. Successfully inhibiting abnormal K-Ras signaling would therefore be a game changer in cancer therapy. However, K-Ras has long been considered an undruggable target for various reasons. This view is now changing by the discovery of allosteric inhibitors that directly target K-Ras and inhibit its functions, and by the identification of new mechanisms to dislodge it from the plasma membrane and thereby abrogate its cellular activities. In this review, we will discuss recent progresses and challenges to inhibiting aberrant K-Ras functions by these two approaches. We will also provide a broad overview of other approaches such as inhibition of K-Ras effectors, and offer a brief perspective on the way forward.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"96-105"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7849769/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45657623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fgd5 is a Rac1-specific Rho GEF that is selectively inhibited by aurintricarboxylic acid.","authors":"Sally Park, Yitian Guo, Judeah Negre, Jordane Preto, Cameron C Smithers, Abul Kalam Azad, Michael Overduin, Allan G Murray, Gary Eitzen","doi":"10.1080/21541248.2019.1674765","DOIUrl":"10.1080/21541248.2019.1674765","url":null,"abstract":"<p><p>Rho proteins are signalling molecules that control cellular dynamics, movement and morphological changes. They are activated by Rho guanine-nucleotide exchange factors (Rho GEFs) that transduce upstream signals into Rho-mediated activation of downstream processes. Fgd5 is a Rho GEF involved in angiogenesis and its target Rho protein for this process has been linked to Cdc42 activation. Here, we examined the function of purified Fgd5, specifically, which Rho proteins it activates and pinpoint the structural domains required for enzymatic activity. Using a GEF enzyme assay, we found that purified Fgd5 showed preferential activation of Rac1 and direct binding of Rac1 in pull-down and co-immunoprecipitation assays. Structural comparisons showed that the Fgd5 DH domain is highly similar to the Rac1 GEF, TrioN, supporting a role for Fgd5 as a Rac1 GEF. Compounds that bind to purified Fgd5 DH-PH protein were identified by screening a small molecule library via surface plasmon resonance. The effects of eleven ligands were further examined for their ability to inhibit the Fgd5 GEF enzymatic activity and Rac1 interaction. From these studies, we found that the compound aurintricarboxylic acid, and to a lesser extent mitoxantrone dihydrochloride, inhibited both Fgd5 GEF activation of Rac1 and their interaction. Aurintricarboxylic acid had no effect on the activity or binding of the Rac1 GEF, TrioN, thus demonstrating the feasibility of selectively disrupting Rho GEF activators. <b>Abbreviations</b>: a.a.: amino acid; ATA: aurintricarboxylic acid; DH: Dbl homology; DOCK: dictator of cytokinesis; Fgd: faciogenital dysplasia; GEF: guanine-nucleotide exchange factor; GST: glutathione <i>S</i>-transferase; LOPAC: library of pharmacologically active compounds; PH: pleckstrin homology; PDB: protein data bank; s.e.m.: standard error of the mean; SPR: surface plasmon resonance.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"147-160"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7849785/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42750169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small GTPases of the Ras superfamily and glycogen phosphorylase regulation in T cells.","authors":"Francisco Llavero, Alazne Arrazola Sastre, Miriam Luque Montoro, Miguel A Martín, Joaquín Arenas, Alejandro Lucia, José L Zugaza","doi":"10.1080/21541248.2019.1665968","DOIUrl":"10.1080/21541248.2019.1665968","url":null,"abstract":"<p><p>Small GTPases, together with their regulatory and effector molecules, are key intermediaries in the complex signalling pathways that control almost all cellular processes, working as molecular switches to transduce extracellular cues into cellular responses that drive vital functions, such as intracellular transport, biomolecule synthesis, gene activation and cell survival. How all of these networks are linked to metabolic pathways is a subject of intensive study. Because any response to cellular action requires some form of energy input, elucidating how cells coordinate the signals that lead to a tangible response involving metabolism is central to understand cellular activities. In this review, we summarize recent advances in our understanding of the molecular basis of the crosstalk between small GTPases of the Ras superfamily, specifically Rac1 and Ras/Rap1, and glycogen phosphorylase in T lymphocytes. <b>Abbreviations</b>: <b>ADCY</b>: adenylyl cyclase; <b>ADCY6</b>: adenylyl cyclase 6; <b>BCR</b>: B cell receptor; <b>cAMP</b>: 3',5'-cyclic adenosine monophosphate; <b>CRIB</b>: Cdc42/Rac binding domain; <b>DLPFC</b>: dysfunction of the dorsolateral prefrontal cortex; <b>EGFR</b>: epidermal growth factor receptor; <b>Epac2</b>: exchange protein directly activated by cAMP; <b>GDP</b>: guanodine-5'-diphosphate; <b>GPCRs</b>: G protein-coupled receptors; <b>GTP</b>: guanodin-5'-triphosphate; <b>IL2</b>: interleukin 2; <b>IL2-R</b>: interleukin 2 receptor; <b>JAK</b>: janus kinases; <b>MAPK</b>: mitogen-activated protein kinase; <b>O-GlcNAc</b>: O-glycosylation; <b>PAK1</b>: p21 activated kinase 1; <b>PI3K</b>: phosphatidylinositol 3-kinase; <b>PK</b>: phosphorylase kinase; <b>PKA</b>: cAMP-dependent protein kinase A; <b>PKCθ</b>: protein kinase Cθ; <b>PLCγ</b>: phospholipase Cγ; <b>Src</b>: proto-oncogene tyrosine-protein kinase c; <b>STAT</b>: signal transducer and activator of transcription proteins.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"106-113"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7849735/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42566011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paradoxical regulation of glucose-induced Rac1 activation and insulin secretion by RhoGDIβ in pancreatic β-cells.","authors":"Vijayalakshmi Thamilselvan, Anjaneyulu Kowluru","doi":"10.1080/21541248.2019.1635403","DOIUrl":"10.1080/21541248.2019.1635403","url":null,"abstract":"<p><p>Small GTPases (e.g., Rac1) play key roles in glucose-stimulated insulin secretion (GSIS) in the β-cell. We investigated regulation by RhoGDIβ of glucose-induced activation of Rac1 and insulin secretion. RhoGDIβ is expressed in INS-1 832/13 cells, rodent and human islets. siRNA-mediated knockdown of RhoGDIβ in INS-1 832/13 cells significantly attenuated glucose-induced Rac1 activation without affecting its translocation and membrane association. Further, suppression of RhoGDIβ expression exerted minimal effects on GSIS at the height of inhibition of Rac1 activation, suggesting divergent effects of RhoGDIβ on Rac1 activation and insulin secretion in the glucose-stimulated β-cell. We provide the first evidence for the expression of RhoGDIβ in rodent and human β-cells, and its differential regulatory roles of this protein in G protein activation and GSIS. <b>Abbreviations</b>: Arf6: ADP ribosylation factor; Cdc42: Cell Division Cycle; GAP: GTPase-activating protein; GDI: GDP dissociation inhibitor; GDIα: GDP dissociation inhibitorα; GDIβ: GDP dissociation inhibitorβ; GEF: Guanine nucleotide exchange factor; GSIS: Glucose-stimulated insulin secretion; Rac1: Ras-Related C3 Botulinum Toxin Substrate 1.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":" ","pages":"114-121"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7849774/pdf/KSGT_12_1635403.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37393756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction.","authors":"","doi":"10.1080/21541248.2020.1713572","DOIUrl":"10.1080/21541248.2020.1713572","url":null,"abstract":"","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"79"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781630/pdf/KSGT_12_1713572.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37535685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of RhoA and RhoC upon the sensitivity of prostate cancer cells to glutamine deprivation.","authors":"Luciana Bueno De Paiva, Vanessa Aline Bernusso, João Agostinho Machado-Neto, Fabiola Traina, Anne J Ridley, Sara Teresinha Olalla-Saad, Mariana Lazarini","doi":"10.1080/21541248.2018.1546098","DOIUrl":"10.1080/21541248.2018.1546098","url":null,"abstract":"<p><p>RhoA and RhoC contribute to the regulation of glutamine metabolism, which is a crucial determinant of cell growth in some types of cancer. Here we investigated the participation of RhoA and RhoC in the response of prostate cancer cells to glutamine deprivation. We found that RhoA and RhoC activities were up- or downregulated by glutamine reduction in PC3 and LNCaP cell lines, which was concomitant to a reduction in cell number and proliferation. Stable overexpression of wild type RhoA or RhoC did not alter the sensitivity to glutamine deprivation. However, PC3 cells expressing dominant negative RhoA^N19 or RhoC^N19 mutants were more resistant to glutamine deprivation. Our results indicate that RhoA and RhoC activities could affect cancer treatments targeting the glutamine pathway.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"20-26"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781845/pdf/KSGT_12_1546098.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36694437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anchorage-independent growth conditions reveal a differential SOS2 dependence for transformation and survival in <i>RAS</i>-mutant cancer cells.","authors":"Erin Sheffels, Nancy E Sealover, Patricia L Theard, Robert L Kortum","doi":"10.1080/21541248.2019.1611168","DOIUrl":"10.1080/21541248.2019.1611168","url":null,"abstract":"<p><p>The RAS family of genes (<i>HRAS, NRAS</i>, and <i>KRAS</i>) is mutated in around 30% of human tumours. Wild-type RAS isoforms play an important role in mutant RAS-driven oncogenesis, indicating that RasGEFs may play a significant role in mutant RAS-driven transformation. We recently reported a hierarchical requirement for SOS2 in mutant RAS-driven transformation in mouse embryonic fibroblasts, with KRAS>NRAS>HRAS (Sheffels et al., 2018). However, whether <i>SOS2</i> deletion differentially affects mutant RAS isoform-dependent transformation in human tumour cell lines has not been tested. After validating sgRNAs that efficiently deleted <i>HRAS</i> and <i>NRAS</i>, we showed that the differential requirement for SOS2 to support anchorage-independent (3D) growth, which we previously demonstrated in MEFs, held true in cancer cells. <i>KRAS</i>-mutant cells showed a high dependence on SOS2 for 3D growth, as previously shown, whereas <i>HRAS</i>-mutant cells did not require SOS2 for 3D growth. This differential requirement was not due to differences in RTK-stimulated WT RAS activation, as SOS2 deletion reduced RTK-stimulated WT RAS/PI3K/AKT signalling in both <i>HRAS</i> and <i>KRAS</i> mutated cell lines. Instead, this differential requirement of SOS2 to promote transformation was due to the differential sensitivity of RAS-mutated cancer cells to reductions in WT RAS/PI3K/AKT signalling. <i>KRAS</i> mutated cancer cells required SOS2/PI3K signaling to protect them from anoikis, whereas survival of both <i>HRAS</i> and <i>NRAS</i> mutated cancer cells was not altered by SOS2 deletion. Finally, we present an integrated working model of SOS signaling in the context of mutant KRAS based on our findings and those of others.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"67-78"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781674/pdf/KSGT_12_1611168.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37381698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Guanine nucleotide exchange factors activate Rab8a for Toll-like receptor signalling.","authors":"Samuel J Tong, Adam A Wall, Yu Hung, Lin Luo, Jennifer L Stow","doi":"10.1080/21541248.2019.1587278","DOIUrl":"10.1080/21541248.2019.1587278","url":null,"abstract":"<p><p>Macrophages are important immune sentinels that detect and clear pathogens and initiate inflammatory responses through the activation of surface receptors, including Toll-like receptors (TLRs). Activated TLRs employ complex cellular trafficking and signalling pathways to initiate transcription for inflammatory cytokine programs. We have previously shown that Rab8a is activated by multiple TLRs and regulates downstream Akt/mTOR signalling by recruiting the effector PI3Kγ, but the guanine nucleotide exchange factors (GEF) canonically required for Rab8a activation in TLR pathways is not known. Using GST affinity pull-downs and mass spectrometry analysis, we identified a Rab8 specific GEF, GRAB, as a Rab8a binding partner in LPS-activated macrophages. Co-immunoprecipitation and fluorescence microscopy showed that both GRAB and a structurally similar GEF, Rabin8, undergo LPS-inducible binding to Rab8a and are localised on cell surface ruffles and macropinosomes where they coincide with sites of Rab8a mediated signalling. Rab nucleotide activation assays with CRISPR-Cas9 mediated knock-out (KO) cell lines of GRAB, Rabin8 and double KOs showed that both GEFs contribute to TLR4 induced Rab8a GTP loading, but not membrane recruitment. In addition, measurement of signalling profiles and live cell imaging with the double KOs revealed that either GEF is individually sufficient to mediate PI3Kγ-dependent Akt/mTOR signalling at macropinosomes during TLR4-driven inflammation, suggesting a redundant relationship between these proteins. Thus, both GRAB and Rabin8 are revealed as key positive regulators of Rab8a nucleotide exchange for TLR signalling and inflammatory programs. These GEFs may be useful as potential targets for manipulating inflammation. <b>Abbreviations:</b> TLR: Toll-like Receptor; OCRL: oculocerebrorenal syndrome of Lowe protein; PI3Kγ: phosphoinositol-3-kinase gamma; LPS: lipopolysaccharide; GEF: guanine nucleotide exchange factor; GST: glutathione S-transferases; BMMs: bone marrow derived macrophages; PH: pleckstrin homology; GAP: GTPase activating protein; ABCA1: ATP binding cassette subfamily A member 1; GDI: GDP dissociation inhibitor; LRP1: low density lipoprotein receptor-related protein 1.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"27-43"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781844/pdf/KSGT_12_1587278.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37207133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A potential Rho GEF and Rac GAP for coupled Rac and Rho cycles during mesenchymal-to-epithelial-like transitions.","authors":"Christopher P Toret, Andre Le Bivic","doi":"10.1080/21541248.2018.1502592","DOIUrl":"10.1080/21541248.2018.1502592","url":null,"abstract":"<p><p>The leading edge-to-cadherin contact transitions that occur during metazoan developmental processes and disease states require fine coordination of Rac and Rho pathways. Recently the elmo-mbc complex, a Rac GEF and RhoGAP19D, a Rho GAP were identified as key, conserved regulators that link Rac and Rho during these transitions. The corresponding Rho GEF and Rac GAP remain hidden amongst the large family of GEF and GAP proteins. Identification of these regulators is essential to understand GTPase coordination during these transitions. Here we find two candidates based on the mammalian literature and use RNAi to explore the fly ortholog effects on the dorsal closure epidermis. RhoGEF64C and RhoGAP92B are strong contenders to couple Rac and Rho during mesenchymal-to-epithelial-like transitions.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"13-19"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781753/pdf/KSGT_12_1502592.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36332916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Allosteric autoactivation of SOS and its kinetic mechanism.","authors":"Hanh My Hoang, Hope Gloria Umutesi, Jongyun Heo","doi":"10.1080/21541248.2019.1601954","DOIUrl":"10.1080/21541248.2019.1601954","url":null,"abstract":"<p><p>Son of Sevenless (SOS), one of guanine nucleotide exchange factors (GEFs), activates Ras. We discovered that the allosteric domain of SOS yields SOS to proceed a previously unrecognized autoactivation kinetics. Its essential feature is a time-dependent acceleration of SOS feedback activation with a reaction initiator or with the priming of active Ras. Thus, this mechanistic autoactivation feature explains the notion, previously only conjectured, of accelerative SOS activation followed by the priming of active Ras, an action produced by another GEF Ras guanyl nucleotide-releasing protein (RasGRP). Intriguingly, the kinetic transition from gradual RasGRP activation to accelerative SOS activation has been interpreted as an analog to digital conversion; however, from the perspective of autoactivation kinetics, it is a process of straightforward RasGRP-mediated SOS autoactivation. From the viewpoint of allosteric protein cooperativity, SOS autoactivation is a unique time-dependent cooperative SOS activation because it enables an active SOS to accelerate activation of other SOS as a function of time. This time-dependent SOS cooperativity does not belong to the classic steady-state protein cooperativity, which depends on ligand concentration. Although its hysteretic or sigmoid-like saturation curvature is a classic hallmark of steady-state protein cooperativity, its hyperbolic saturation figure typically represents protein noncooperativity. We also discovered that SOS autoactivation perturbs the previously predicted hysteresis of SOS activation in a steady state to produce a hyperbolic saturation curve. We interpret this as showing that SOS allostery elicits, through SOS autoactivation, cooperativity uniquely time-dependent but not ligand concentration dependent.</p>","PeriodicalId":22139,"journal":{"name":"Small GTPases","volume":"12 1","pages":"44-59"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781538/pdf/KSGT_12_1601954.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37151100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}