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Mohapatra T, Dixit M. IQ Motif Containing GTPase Activating Proteins (IQGAPs), A-Kinase Anchoring Proteins (AKAPs) and Kinase Suppressor of Ras Proteins (KSRs) in Scaffolding Oncogenic Pathways and Their Therapeutic Potential. ACS OMEGA 2022; 7:45837-45848. [PMID: 36570181 PMCID: PMC9773950 DOI: 10.1021/acsomega.2c05505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Scaffolding proteins colocalize interacting partners on their surface and facilitate complex formation. They have multiple domains and motifs, which provide binding sites for various molecules. This property of scaffolding proteins helps in the orderly transduction of signals. Abnormal signal transduction is frequently observed in cancers, which can also be attributed to the altered functionality of scaffolding proteins. IQ motif containing GTPase activating proteins (IQGAPs), kinase suppressor of Ras (KSR), and A-kinase anchoring proteins (AKAPs) tether oncogenic pathways RAS/RAF/MEK/ERK, PI3K/AKT, Hippo, Wnt, and CDC42/RAC to them. Scaffolding proteins are attractive drug targets as they are the controlling hub for multiple pathways and regulate crosstalk between them. The first part of this review describes the human scaffolding proteins known to play a role in oncogenesis, pathways altered by them, and the impact on oncogenic processes. The second part provides information on the therapeutic potential of scaffolding proteins and future possibilities. The information on the explored and unexplored areas of the therapeutic potential of scaffolding proteins will be equally helpful for biologists and chemists.
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Affiliation(s)
- Talina Mohapatra
- National
Institute of Science Education and Research, School of Biological Sciences, Bhubaneswar, Odisha 752050, India
- Homi
Bhabha National Institute, Training School
Complex, Anushaktinagar, Mumbai 400094, India
| | - Manjusha Dixit
- National
Institute of Science Education and Research, School of Biological Sciences, Bhubaneswar, Odisha 752050, India
- Homi
Bhabha National Institute, Training School
Complex, Anushaktinagar, Mumbai 400094, India
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2
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Khan S, Patra PH, Somerfield H, Benya-Aphikul H, Upadhya M, Zhang X. IQGAP1 promotes chronic pain by regulating the trafficking and sensitization of TRPA1 channels. Brain 2022:6881565. [PMID: 36477832 DOI: 10.1093/brain/awac462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/14/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
TRPA1 channels have been implicated in mechanical and cold hypersensitivity in chronic pain. But how TRPA1 mediates this process is unclear. Here we show that IQ-motif containing GTPase activating protein 1 (IQGAP1) is responsible using a combination of biochemical, molecular, Ca2+ imaging and behavioural approaches. TRPA1 and IQGAP1 bind to each other and are highly colocalised in sensory DRG neurons in mice. The expression of IQGAP1 but not TRPA1 is increased in chronic inflammatory and neuropathic pain. However, TRPA1 undergoes increased trafficking to the membrane of DRG neurons catalysed by the small GTPase Cdc42 associated with IQGAP1, leading to functional sensitization of the channel. Activation of PKA is also sufficient to evoke TRPA1 trafficking and sensitization. All these responses are, however, completely prevented in the absence of IQGAP1. Concordantly, deletion of IQGAP1 markedly reduces mechanical and cold hypersensitivity in chronic inflammatory and neuropathic pain in mice. IQGAP1 thus promotes chronic pain by coupling the trafficking and signalling machineries to TRPA1 channels.
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Affiliation(s)
- Shakil Khan
- School of Health & Life Sciences, Aston University, Birmingham B4 7ET, UK
| | - Pabitra H Patra
- School of Health & Life Sciences, Aston University, Birmingham B4 7ET, UK
| | - Hannah Somerfield
- School of Health & Life Sciences, Aston University, Birmingham B4 7ET, UK
| | | | - Manoj Upadhya
- School of Health & Life Sciences, Aston University, Birmingham B4 7ET, UK
| | - Xuming Zhang
- School of Health & Life Sciences, Aston University, Birmingham B4 7ET, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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3
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CDKL5 deficiency disorder: molecular insights and mechanisms of pathogenicity to fast-track therapeutic development. Biochem Soc Trans 2022; 50:1207-1224. [PMID: 35997111 PMCID: PMC9444073 DOI: 10.1042/bst20220791] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/28/2022] [Accepted: 07/28/2022] [Indexed: 12/02/2022]
Abstract
CDKL5 deficiency disorder (CDD) is an X-linked brain disorder of young children and is caused by pathogenic variants in the cyclin-dependent kinase-like 5 (CDKL5) gene. Individuals with CDD suffer infantile onset, drug-resistant seizures, severe neurodevelopmental impairment and profound lifelong disability. The CDKL5 protein is a kinase that regulates key phosphorylation events vital to the development of the complex neuronal network of the brain. Pathogenic variants identified in patients may either result in loss of CDKL5 catalytic activity or are hypomorphic leading to partial loss of function. Whilst the progressive nature of CDD provides an excellent opportunity for disease intervention, we cannot develop effective therapeutics without in-depth knowledge of CDKL5 function in human neurons. In this mini review, we summarize new findings on the function of CDKL5. These include CDKL5 phosphorylation targets and the consequence of disruptions on signaling pathways in the human brain. This new knowledge of CDKL5 biology may be leveraged to advance targeted drug discovery and rapid development of treatments for CDD. Continued development of effective humanized models will further propel our understanding of CDD biology and may permit the development and testing of therapies that will significantly alter CDD disease trajectory in young children.
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CDC42-IQGAP Interactions Scrutinized: New Insights into the Binding Properties of the GAP-Related Domain. Int J Mol Sci 2022; 23:ijms23168842. [PMID: 36012107 PMCID: PMC9408373 DOI: 10.3390/ijms23168842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/05/2022] [Accepted: 08/06/2022] [Indexed: 11/17/2022] Open
Abstract
The IQ motif-containing GTPase-activating protein (IQGAP) family composes of three highly-related and evolutionarily conserved paralogs (IQGAP1, IQGAP2 and IQGAP3), which fine tune as scaffolding proteins numerous fundamental cellular processes. IQGAP1 is described as an effector of CDC42, although its effector function yet re-mains unclear. Biophysical, biochemical and molecular dynamic simulation studies have proposed that IQGAP RASGAP-related domains (GRDs) bind to the switch regions and the insert helix of CDC42 in a GTP-dependent manner. Our kinetic and equilibrium studies have shown that IQGAP1 GRD binds, in contrast to its C-terminal 794 amino acids (called C794), CDC42 in a nucleotide-independent manner indicating a binding outside the switch regions. To resolve this discrepancy and move beyond the one-sided view of GRD, we carried out affinity measurements and a systematic mutational analysis of the interfacing residues between GRD and CDC42 based on the crystal structure of the IQGAP2 GRD-CDC42Q61L GTP complex. We determined a 100-fold lower affinity of the GRD1 of IQGAP1 and of GRD2 of IQGAP2 for CDC42 mGppNHp in comparison to C794/C795 proteins. Moreover, partial and major mutation of CDC42 switch regions substantially affected C794/C795 binding but only a little GRD1 and remarkably not at all the GRD2 binding. However, we clearly showed that GRD2 contributes to the overall affinity of C795 by using a 11 amino acid mutated GRD variant. Furthermore, the GRD1 binding to the CDC42 was abolished using specific point mutations within the insert helix of CDC42 clearly supporting the notion that CDC42 binding site(s) of IQGAP GRD lies outside the switch regions among others in the insert helix. Collectively, this study provides further evidence for a mechanistic framework model that is based on a multi-step binding process, in which IQGAP GRD might act as a ‘scaffolding domain’ by binding CDC42 irrespective of its nucleotide-bound forms, followed by other IQGAP domains downstream of GRD that act as an effector domain and is in charge for a GTP-dependent interaction with CDC42.
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Li B, Zhang Z, Wan C. Identification of Microproteins in Hep3B Cells at Different Cell Cycle Stages. J Proteome Res 2022; 21:1052-1060. [PMID: 35199523 DOI: 10.1021/acs.jproteome.1c00926] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microproteins are generated from small open reading frames and turn out to play various vital biological functions. As an essential biological event of eukaryotic cells, the cell cycle is involved in cell replication and division. For such a highly regulated event, microproteins associated with cell cycle regulation remained unclarified. Utilizing a combination of bottom-up and top-down proteomics, we analyzed microproteins at specific cell cycle stages of Hep3B cells. A total of 657 microproteins were identified under three cell cycle stages, including 151 in the G0/G1 stage, 163 in the S stage, and 132 in the G2/M stage. The annotation of these microproteins showed their cell cycle-specific functions, such as translation, nuclear assembly, chromatin organization, and the G2/M transition of the mitotic cell cycle. Meanwhile, more than 50% of identified microproteins were ncRNA-encoded. These nonannotated novel microproteins contain several function domains, such as the nucleoside diphosphate kinase domain, the high mobility group domain, and the DNA-binding domain. This suggested the potential functions of these novel microproteins in specific cell cycle stages. This study presented a large-scale profile of microproteins at different cell cycle stages from Hep3B and may provide new perspectives on the regulation mechanism of the cell cycle. Liquid chromatography-mass spectrometry data were deposited to ProteomeXchange using the identifier PXD030286.
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Affiliation(s)
- Bing Li
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei 430079, People's Republic of China
| | - Zheng Zhang
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei 430079, People's Republic of China
| | - Cuihong Wan
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei 430079, People's Republic of China
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Mosaddeghzadeh N, Nouri K, Krumbach OHF, Amin E, Dvorsky R, Ahmadian MR. Selectivity Determinants of RHO GTPase Binding to IQGAPs. Int J Mol Sci 2021; 22:12596. [PMID: 34830479 PMCID: PMC8625570 DOI: 10.3390/ijms222212596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022] Open
Abstract
IQ motif-containing GTPase-activating proteins (IQGAPs) modulate a wide range of cellular processes by acting as scaffolds and driving protein components into distinct signaling networks. Their functional states have been proposed to be controlled by members of the RHO family of GTPases, among other regulators. In this study, we show that IQGAP1 and IQGAP2 can associate with CDC42 and RAC1-like proteins but not with RIF, RHOD, or RHO-like proteins, including RHOA. This seems to be based on the distribution of charged surface residues, which varies significantly among RHO GTPases despite their high sequence homology. Although effector proteins bind first to the highly flexible switch regions of RHO GTPases, additional contacts outside are required for effector activation. Sequence alignment and structural, mutational, and competitive biochemical analyses revealed that RHO GTPases possess paralog-specific residues outside the two highly conserved switch regions that essentially determine the selectivity of RHO GTPase binding to IQGAPs. Amino acid substitution of these specific residues in RHOA to the corresponding residues in RAC1 resulted in RHOA association with IQGAP1. Thus, electrostatics most likely plays a decisive role in these interactions.
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Affiliation(s)
- Niloufar Mosaddeghzadeh
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
| | - Kazem Nouri
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Oliver H. F. Krumbach
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
| | - Ehsan Amin
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
- Medical Faculty, Institute of Neural and Sensory Physiology, University Hospital Düsseldorf, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Radovan Dvorsky
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
| | - Mohammad R. Ahmadian
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (N.M.); (K.N.); (O.H.F.K.); (E.A.); (R.D.)
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7
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Hoeprich GJ, Sinclair AN, Shekhar S, Goode BL. Single-molecule imaging of IQGAP1 regulating actin filament dynamics. Mol Biol Cell 2021; 33:ar2. [PMID: 34731043 PMCID: PMC8886817 DOI: 10.1091/mbc.e21-04-0211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
IQGAP is a conserved family of actin-binding proteins with essential roles in cell motility, cytokinesis, and cell adhesion, yet there remains a limited understanding of how IQGAP proteins directly influence actin filament dynamics. To close this gap, we used single-molecule and single-filament total internal reflection fluorescence microscopy to observe IQGAP regulating actin dynamics in real time. To our knowledge, this is the first study to do so. Our results demonstrate that full-length human IQGAP1 forms dimers that stably bind to actin filament sides and transiently cap barbed ends. These interactions organize filaments into thin bundles, suppress barbed end growth, and inhibit filament disassembly. Surprisingly, each activity depends on distinct combinations of IQGAP1 domains and/or dimerization, suggesting that different mechanisms underlie each functional effect on actin. These observations have important implications for how IQGAP functions as an actin regulator in vivo and how it may be regulated in different biological settings.
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Affiliation(s)
- Gregory J Hoeprich
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Amy N Sinclair
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
| | - Shashank Shekhar
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA.,Present address: Departments of Physics and Cell Biology, Emory University, Atlanta, GA 30322
| | - Bruce L Goode
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02453, USA
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8
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Wei T, Lambert PF. Role of IQGAP1 in Carcinogenesis. Cancers (Basel) 2021; 13:3940. [PMID: 34439095 PMCID: PMC8391515 DOI: 10.3390/cancers13163940] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/28/2021] [Accepted: 08/02/2021] [Indexed: 12/31/2022] Open
Abstract
Scaffolding proteins can play important roles in cell signaling transduction. IQ motif-containing GTPase-activating protein 1 (IQGAP1) influences many cellular activities by scaffolding multiple key signaling pathways, including ones involved in carcinogenesis. Two decades of studies provide evidence that IQGAP1 plays an essential role in promoting cancer development. IQGAP1 is overexpressed in many types of cancer, and its overexpression in cancer is associated with lower survival of the cancer patient. Here, we provide a comprehensive review of the literature regarding the oncogenic roles of IQGAP1. We start by describing the major cancer-related signaling pathways scaffolded by IQGAP1 and their associated cellular activities. We then describe clinical and molecular evidence for the contribution of IQGAP1 in different types of cancers. In the end, we review recent evidence implicating IQGAP1 in tumor-related immune responses. Given the critical role of IQGAP1 in carcinoma development, anti-tumor therapies targeting IQGAP1 or its associated signaling pathways could be beneficial for patients with many types of cancer.
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Affiliation(s)
| | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA;
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Hill TW, Wendt KE, Jones DA, Williamson MH, Ugwu UJ, Rowland LB, Jackson-Hayes L. The Aspergillus nidulans IQGAP orthologue SepG is required for constriction of the contractile actomyosin ring. Fungal Genet Biol 2020; 144:103439. [PMID: 32768603 DOI: 10.1016/j.fgb.2020.103439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/14/2020] [Accepted: 07/28/2020] [Indexed: 10/23/2022]
Abstract
In this research we report that the sepG1 mutation in Aspergillus nidulans resides in gene AN9463, which is predicted to encode an IQGAP orthologue. The genetic lesion is predicted to result in a G-to-R substitution at residue 1637 of the 1737-residue protein in a highly conserved region of the RasGAP-C-terminal (RGCT) domain. When grown at restrictive temperature, strains expressing the sepGG1637R (sepG1) allele are aseptate, with reduced colony growth and aberrantly formed conidiophores. The aseptate condition can be replicated by deletion of AN9463 or by downregulating its expression via introduced promoters. The mutation does not prevent assembly of a cortical contractile actomyosin ring (CAR) at putative septation sites, but tight compaction of the rings is impaired and the rings fail to constrict. Both GFP::SepG wild type and the GFP-tagged product of the sepG1 allele localize to the CAR at both permissive and restrictive temperatures. Downregulation of myoB (encoding the A. nidulans type-II myosin heavy chain) does not prevent formation of SepG rings at septation sites, but filamentous actin is required for CAR localization of SepG and MyoB. We identify fourteen probable IQ-motifs (EF-hand protein binding sites) in the predicted SepG sequence. Two of the A. nidulans EF-hand proteins, myosin essential light chain (AnCdc4) and myosin regulatory light chain (MrlC), colocalize with SepG and MyoB at all stages of CAR formation and constriction. However, calmodulin (CamA) appears at septation sites only after the CAR has become fully compacted. When expression of sepG is downregulated, leaving MyoB as the sole IQ-motif protein in the pre-compaction CAR, both MrlC and AnCdc4 continue to associate with the forming CAR. When myoB expression is downregulated, leaving SepG as the sole IQ-motif protein in the CAR, AnCdc4 association with the forming CAR continues but MrlC fails to associate. This supports a model in which the IQ motifs of MyoB bind both MrlC and AnCdc4, while the IQ motifs of SepG bind only AnCdc4. Downregulation of either mrlC or Ancdc4 results in an aseptate phenotype, but has no effect on association of either SepG or MyoB with the CAR.
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Affiliation(s)
- Terry W Hill
- Department of Biology, Rhodes College, Memphis, TN 38112, USA; Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA.
| | - Kristen E Wendt
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - David A Jones
- Department of Chemistry, Rhodes College, Memphis, TN 38112, USA
| | - McLean H Williamson
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - Uchenna J Ugwu
- Division of Natural & Mathematic Sciences, LeMoyne-Owen College, Memphis, TN 38126, USA
| | - Lauren B Rowland
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA
| | - Loretta Jackson-Hayes
- Biochemistry and Molecular Biology Program, Rhodes College, Memphis, TN 38112, USA; Department of Chemistry, Rhodes College, Memphis, TN 38112, USA
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Chuang HC, Chang CC, Teng CF, Hsueh CH, Chiu LL, Hsu PM, Lee MC, Hsu CP, Chen YR, Liu YC, Lyu PC, Tan TH. MAP4K3/GLK Promotes Lung Cancer Metastasis by Phosphorylating and Activating IQGAP1. Cancer Res 2019; 79:4978-4993. [DOI: 10.1158/0008-5472.can-19-1402] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/04/2019] [Accepted: 08/02/2019] [Indexed: 11/16/2022]
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11
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IQGAP1 mediates podocyte injury in diabetic kidney disease by regulating nephrin endocytosis. Cell Signal 2019; 59:13-23. [DOI: 10.1016/j.cellsig.2019.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
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12
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Lamm N, Rogers S, Cesare AJ. The mTOR pathway: Implications for DNA replication. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:17-25. [PMID: 30991055 DOI: 10.1016/j.pbiomolbio.2019.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/01/2019] [Accepted: 04/09/2019] [Indexed: 12/22/2022]
Abstract
DNA replication plays a central role in genome health. Deleterious alteration of replication dynamics, or "replication stress", is a key driver of genome instability and oncogenesis. The replication stress response is regulated by the ATR kinase, which functions to mitigate replication abnormalities through coordinated efforts that arrest the cell cycle and repair damaged replication forks. mTOR kinase regulates signaling networks that control cell growth and metabolism in response to environmental cues and cell stress. In this review, we discuss interconnectivity between the ATR and mTOR pathways, and provide putative mechanisms for mTOR engagement in DNA replication and the replication stress response. Finally, we describe how connectivity between mTOR and replication stress may be exploited for cancer therapy.
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Affiliation(s)
- Noa Lamm
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Samuel Rogers
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Anthony J Cesare
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia.
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13
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Wang Z, Cai M, Tay LWR, Zhang F, Wu P, Huynh A, Cao X, Di Paolo G, Peng J, Milewicz DM, Du G. Phosphatidic acid generated by PLD2 promotes the plasma membrane recruitment of IQGAP1 and neointima formation. FASEB J 2019; 33:6713-6725. [PMID: 30811216 DOI: 10.1096/fj.201800390rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Very little is known about how lipid signaling regulates intima hyperplasia after vascular injury. Herein, we report that deletion and pharmacological inhibition of phospholipase D (PLD)2, which generates the signaling lipid phosphatidic acid (PA), reduced neointimal formation in the mouse carotid artery ligation model. PLD2 deficiency inhibits migration of vascular smooth muscle cells (VSMCs) into the intima in mice as well as migration and formation of membrane ruffles in primary VSMCs. PA specifically binds to the IQ motif-containing guanosine triphosphatase-activating protein 1 (IQGAP1) scaffold protein. The binding between PA and IQGAP is required for the plasma membrane recruitment of IQGAP1. Similar to PLD2 inhibition, knockdown of IQGAP1 blocks ruffle formation and migration in VSMCs, which are rescued by expression of the exogenous IQGAP1 but not the PA binding-deficient mutant. These data reveal that the PLD2-PA-IQGAP1 pathway plays an important role in VSMC migration and injury-induced vascular remodeling, and implicate PLD2 as a candidate target for therapeutic interventions.-Wang, Z., Cai, M., Tay, L. W. R., Zhang, F., Wu, P., Huynh, A., Cao, X., Di Paolo, G., Peng, J., Milewicz, D. M., Du, G. Phosphatidic acid generated by PLD2 promotes the plasma membrane recruitment of IQGAP1 and neointima formation.
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Affiliation(s)
- Ziqing Wang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ming Cai
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA.,Department of Gastrointestinal Surgery, Union Hospital-Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li Wei Rachel Tay
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Feng Zhang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ping Wu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Anh Huynh
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Xiumei Cao
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, USA
| | - Junmin Peng
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; and
| | - Dianna M Milewicz
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Guangwei Du
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas, USA
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14
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Vodicska B, Cerikan B, Schiebel E, Hoffmann I. MISP regulates the IQGAP1/Cdc42 complex to collectively orchestrate spindle orientation and mitotic progression. Sci Rep 2018; 8:6330. [PMID: 29679050 PMCID: PMC5910412 DOI: 10.1038/s41598-018-24682-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/26/2018] [Indexed: 01/02/2023] Open
Abstract
Precise mitotic spindle orientation is essential for both cell fate and tissue organization while defects in this process are associated with tumorigenesis and other diseases. In most animal cell types, the dynein motor complex is anchored at the cell cortex and exerts pulling forces on astral microtubules to position the spindle. The actin-binding protein MISP controls spindle orientation and mitotic progression in human cells. However, the exact underlying mechanism remains to be elucidated. Here we report that MISP interacts with the multidomain scaffolding protein IQGAP1. We further show that MISP binds to the active form of Cdc42 through IQGAP1. Depletion of MISP promotes increased accumulation of IQGAP1 at the cell cortex and a decrease in its Cdc42-binding capacity leading to reduced active Cdc42 levels. Interestingly, overexpression of IQGAP1 can rescue mitotic defects caused by MISP downregulation including spindle misorientation, loss of astral microtubules and prolonged mitosis and also restores active Cdc42 levels. Importantly, we find that IQGAP1 acts downsteam of MISP in regulating astral microtubule dynamics and the localization of the dynactin subunit p150glued that is crucial for proper spindle positioning. We propose that MISP regulates IQGAP1 and Cdc42 to ensure proper mitotic progression and correct spindle orientation.
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Affiliation(s)
- Barbara Vodicska
- Cell Cycle Control and Carcinogenesis, F045, German Cancer Research Center, DKFZ, 69120, Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Berati Cerikan
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ - ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ - ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Ingrid Hoffmann
- Cell Cycle Control and Carcinogenesis, F045, German Cancer Research Center, DKFZ, 69120, Heidelberg, Germany.
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15
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Barbiero I, Peroni D, Tramarin M, Chandola C, Rusconi L, Landsberger N, Kilstrup-Nielsen C. The neurosteroid pregnenolone reverts microtubule derangement induced by the loss of a functional CDKL5-IQGAP1 complex. Hum Mol Genet 2018. [PMID: 28641386 DOI: 10.1093/hmg/ddx237] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
CDKL5 is a protein kinase that plays a key role for neuronal functions as testified by the onset of complex neuronal dysfunctions in patients with genetic lesions in CDKL5. Here we identify a novel interactor of CDKL5, IQGAP1, a fundamental regulator of cell migration and polarity. In accordance with a functional role of this interaction, depletion of CDKL5 impairs cell migration and impedes the localization of IQGAP1 at the leading edge. Moreover, we demonstrate that CDKL5 is required for IQGAP1 to form a functional complex with its effectors, Rac1 and the microtubule plus end tracking protein CLIP170. These defects eventually impact on the microtubule association of CLIP170, thus deranging their dynamics. CLIP170 is a cellular target of the neurosteroid pregnenolone; by blocking CLIP170 in its active conformation, pregnenolone is capable of restoring the microtubule association of CLIP170 in CDKL5 deficient cells and rescuing morphological defects in neurons devoid of CDKL5. These findings provide novel insights into CDKL5 functions and pave the way for target-specific therapeutic strategies for individuals affected with CDKL5-disorder.
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Affiliation(s)
- Isabella Barbiero
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
| | - Diana Peroni
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
| | - Marco Tramarin
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
| | - Chetan Chandola
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
| | - Laura Rusconi
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
| | - Nicoletta Landsberger
- Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129 Milan, Italy
| | - Charlotte Kilstrup-Nielsen
- Department of Biotechnology and Life Sciences and Center of Neuroscience, University of Insubria, 21052 Busto Arsizio, Italy
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16
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Wang H, Baladandayuthapani V, Wang Z, Lin H, Berkova Z, Davis RE, Yang L, Orlowski RZ. Truncated protein tyrosine phosphatase receptor type O suppresses AKT signaling through IQ motif containing GTPase activating protein 1 and confers sensitivity to bortezomib in multiple myeloma. Oncotarget 2017; 8:113858-113873. [PMID: 29371952 PMCID: PMC5768369 DOI: 10.18632/oncotarget.23017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 11/20/2017] [Indexed: 11/25/2022] Open
Abstract
Proteasome inhibitors are an important part of our chemotherapeutic armamentarium against multiple myeloma, but the vast majority of patients eventually develop drug-resistant disease through incompletely understood mechanisms. Comparison of gene expression profiles (GEPs) of bortezomib-resistant (BR) myeloma cell lines with their drug-naïve counterparts revealed decreased expression of truncated Protein tyrosine phosphatase receptor-type O (PTPROt) in BR cells. Over-expression of wild-type PTPROt in drug-naïve and BR cells reduced myeloma cell proliferation, induced apoptosis, and sensitized cells to bortezomib and to alkylating agents. PTPROt expression reduced AKT phosphorylation and activity, and sensitized to pharmacologic AKT pathway inhibitors, but this was not the case for a substrate-trapping catalytic domain-inactivating mutant. Co-immunoprecipitation and mass spectrometry studies identified IQ motif containing GTPase activating protein 1 (IQGAP1) as a PTPROt binding partner, and PTPROt reduced tyrosine phosphorylation of IQGAP1, providing a link to AKT activity. Analysis of clinically annotated GEP databases identified high PTPROt expression as being related to an increased likelihood of achieving complete remission with bortezomib therapy, while low expression was linked to a greater likelihood of disease progression. Finally, high PTPROt expression associated with prolonged median overall survival in patients receiving bortezomib-based therapy in the front-line or relapsed and/or refractory settings. Taken together, these data identify PTPROt suppression as a novel mechanism of myeloma resistance to bortezomib in myeloma cell lines, and also support the possibility that PTPROt expression could be used as a biomarker to predict outcomes with bortezomib, and by which to select patients for therapy with AKT inhibitors.
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Affiliation(s)
- Hua Wang
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Zhiqiang Wang
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Heather Lin
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Zuzana Berkova
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Richard E Davis
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Lin Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, China
| | - Robert Z Orlowski
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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17
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Reimer M, Denby E, Zustiak SP, Schober JM. Ras GAP-related and C-terminal domain-dependent localization and tumorigenic activities of IQGAP1 in melanoma cells. PLoS One 2017; 12:e0189589. [PMID: 29240845 PMCID: PMC5730206 DOI: 10.1371/journal.pone.0189589] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/29/2017] [Indexed: 12/19/2022] Open
Abstract
IQGAP1 interacts with a number of binding partners through a calponin homology domain (CHD), a WW motif, IQ repeats, a Ras GAP-related domain (GRD), and a conserved C-terminal (CT) domain. Among various biological and cellular functions, IQGAP1 is known to play a role in actin cytoskeleton dynamics during membrane ruffling and lamellipodium protrusion. In addition, phosphorylation near the CT domain is thought to control IQGAP1 activity through regulation of intramolecular interaction. In a previous study, we discovered that IQGAP1 preferentially localizes to retracting areas in B16F10 mouse melanoma cells, not areas of membrane ruffling and lamellipodium protrusion. Nothing is known of the domains needed for retraction localization and very little is known of IQGAP1 function in the actin cytoskeleton of melanoma cells. Thus, we examined localization of IQGAP1 mutants to retracting areas, and characterized knock down phenotypes on tissue culture plastic and physiologic-stiffness hydrogels. Localization of IQGAP1 mutants (S1441E/S1443D, S1441A/S1443A, ΔCHD, ΔGRD or ΔCT) to retracting and protruding cell edges were measured. In retracting areas there was a decrease in S1441A/S1443A, ΔGRD and ΔCT localization, a minor decrease in ΔCHD localization, and normal localization of the S1441E/S1443D mutant. In areas of cell protrusion just behind the lamellipodium leading edge, we surprisingly observed both ΔGRD and ΔCT localization, and increased number of microtubules. IQGAP1 knock down caused loss of cell polarity on laminin-coated glass, decreased proliferation on tissue culture polystyrene, and abnormal spheroid growth on laminin-coated hydrogels. We propose that the GRD and CT domains regulate IQGAP1 localization to retracting actin networks to promote a tumorigenic role in melanoma cells.
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Affiliation(s)
- Michael Reimer
- Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
| | - Elisabeth Denby
- Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
| | - Silviya P. Zustiak
- Department of Biomedical Engineering, Saint Louis University, Saint Louis, Missouri, United States of America
| | - Joseph M. Schober
- Department of Pharmaceutical Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
- * E-mail:
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18
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Liang Z, Yang Y, He Y, Yang P, Wang X, He G, Zhang P, Zhu H, Xu N, Zhao X, Liang S. SUMOylation of IQGAP1 promotes the development of colorectal cancer. Cancer Lett 2017; 411:90-99. [PMID: 28987385 DOI: 10.1016/j.canlet.2017.09.046] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 09/23/2017] [Accepted: 09/25/2017] [Indexed: 02/05/2023]
Abstract
IQGAP1 is a conserved multifunctional protein implicated in tumorigenesis. An aberrant expression of IQGAP1 widely exists in many cancers, but the SUMOylation modification of IQGAP1 in carcinogenesis is unknown by now. Here we first time explore biological functions of IQGAP1 SUMOylation in promoting colorectal cancer progression in vitro and in vivo. The expression of IQGAP1 and its SUMOylation level are both increased in human colorectal carcinoma (CRC) cells and tissues. IQGAP1 is mainly SUMOylated by SUMO1 at the K1445 residue, which could stabilize IQGAP1 by reducing protein ubiquitination. IQGAP1 SUMOylation improves CRC cell growth, cell migration and tumorigenesis in vivo through activating the phosphorylation of ERK, MEK and AKT. While the SUMOylation site mutation at K1445 of IQGAP1 greatly reduces CRC cell proliferation, migration ability and tumor growth of CRC-xenograft mice by suppressing phosphorylation of ERK, MEK and AKT. Our findings discover the IQGAP1 SUMOylation is a novel regulatory mechanism to enhance tumorigenesis and development of CRC in vitro and in vivo.
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Affiliation(s)
- Ziwei Liang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Yanfang Yang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Yu He
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Pengbo Yang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Xixi Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Gu He
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China
| | - Peng Zhang
- Department of Urinary Surgery, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, PR China
| | - Hongxia Zhu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, Cancer Institute & Cancer Hospital, Chinese Academy of Medical Sciences, Beijing, 100034, PR China
| | - Ningzhi Xu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China; Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, Cancer Institute & Cancer Hospital, Chinese Academy of Medical Sciences, Beijing, 100034, PR China
| | - Xia Zhao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China; Department of Gynecology and Obstetrics, West China Second Hospital, Sichuan University, Chengdu, 610041, PR China
| | - Shufang Liang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, No.17, 3rd Section of People's South Road, Chengdu, 610041, PR China.
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19
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Carmon KS, Gong X, Yi J, Wu L, Thomas A, Moore CM, Masuho I, Timson DJ, Martemyanov KA, Liu QJ. LGR5 receptor promotes cell-cell adhesion in stem cells and colon cancer cells via the IQGAP1-Rac1 pathway. J Biol Chem 2017; 292:14989-15001. [PMID: 28739799 PMCID: PMC5592675 DOI: 10.1074/jbc.m117.786798] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/21/2017] [Indexed: 12/18/2022] Open
Abstract
Leucine-rich repeat-containing G protein–coupled receptor 5 (LGR5) is a bona fide marker of adult stem cells in several epithelial tissues, most notably in the intestinal crypts, and is highly up-regulated in many colorectal, hepatocellular, and ovarian cancers. LGR5 activation by R-spondin (RSPO) ligands potentiates Wnt/β-catenin signaling in vitro; however, deletion of LGR5 in stem cells has little or no effect on Wnt/β-catenin signaling or cell proliferation in vivo. Remarkably, modulation of LGR5 expression has a major impact on the actin cytoskeletal structure and cell adhesion in the absence of RSPO stimulation, but the molecular mechanism is unclear. Here, we show that LGR5 interacts with IQ motif-containing GTPase-activating protein 1 (IQGAP1), an effector of Rac1/CDC42 GTPases, in the regulation of actin cytoskeleton dynamics and cell–cell adhesion. Specifically, LGR5 decreased levels of IQGAP1 phosphorylation at Ser-1441/1443, leading to increased binding of Rac1 to IQGAP1 and thus higher levels of cortical F-actin and enhanced cell–cell adhesion. LGR5 ablation in colon cancer cells and crypt stem cells resulted in loss of cortical F-actin, reduced cell–cell adhesion, and disrupted localization of adhesion-associated proteins. No evidence of LGR5 coupling to any of the four major subtypes of heterotrimeric G proteins was found. These findings suggest that LGR5 primarily functions via the IQGAP1–Rac1 pathway to strengthen cell–cell adhesion in normal adult crypt stem cells and colon cancer cells.
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Affiliation(s)
- Kendra S Carmon
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030
| | - Xing Gong
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030
| | - Jing Yi
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030.,Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Ling Wu
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030
| | - Anthony Thomas
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030
| | - Catherine M Moore
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Ireland, United Kingdom
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, and
| | - David J Timson
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Ireland, United Kingdom.,School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, United Kingdom
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, and
| | - Qingyun J Liu
- From the Brown Foundation Institute of Molecular Medicine and Texas Therapeutics Institute, University of Texas Health Science Center, Houston, Texas 77030,
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20
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Abstract
The specific and rapid formation of protein complexes, involving IQGAP family proteins, is essential for diverse cellular processes, such as adhesion, polarization, and directional migration. Although CDC42 and RAC1, prominent members of the RHO GTPase family, have been implicated in binding to and activating IQGAP1, the exact nature of this protein-protein recognition process has remained obscure. Here, we propose a mechanistic framework model that is based on a multiple-step binding process, which is a prerequisite for the dynamic functions of IQGAP1 as a scaffolding protein and a critical mechanism in temporal regulation and integration of cellular pathways.
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Affiliation(s)
- Kazem Nouri
- Institute of Biochemistry and Molecular Biology II, Medical faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, United Kingdom
| | - Mohammad R Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical faculty of the Heinrich-Heine University, Düsseldorf, Germany
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21
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Abstract
Exocytosis is a fundamental cellular process whereby secreted molecules are packaged into vesicles that move along cytoskeletal filaments and fuse with the plasma membrane. To function optimally, cells are strongly dependent on precisely controlled delivery of exocytotic cargo. In mammalian cells, microtubules serve as major tracks for vesicle transport by motor proteins, and thus microtubule organization is important for targeted delivery of secretory carriers. Over the years, multiple microtubule-associated and cortical proteins have been discovered that facilitate the interaction between the microtubule plus ends and the cell cortex. In this review, we focus on mammalian protein complexes that have been shown to participate in both cortical microtubule capture and exocytosis, thereby regulating the spatial organization of secretion. These complexes include microtubule plus-end tracking proteins, scaffolding factors, actin-binding proteins, and components of vesicle docking machinery, which together allow efficient coordination of cargo transport and release.
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Affiliation(s)
- Ivar Noordstra
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
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22
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Cui Y, Li Q, Li H, Wang Y, Wang H, Chen W, Zhang S, Cao J, Liu T. Asparaginyl endopeptidase improves the resistance of microtubule-targeting drugs in gastric cancer through IQGAP1 modulating the EGFR/JNK/ERK signaling pathway. Onco Targets Ther 2017; 10:627-643. [PMID: 28223821 PMCID: PMC5304996 DOI: 10.2147/ott.s125579] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
PURPOSE In recent years, understanding of the role of asparaginyl endopeptidase (AEP) in tumorigenesis has steadily increased. In this study, we investigated whether AEP expression correlates with sensitivity to chemotherapeutic drugs in gastric cancer and explored the mechanism. PATIENTS AND METHODS AEP expression in the serum of patients' peripheral blood was measured by enzyme-linked immunosorbent assay. Patient survival time was evaluated using univariate and multivariate analyses. Mass spectrometry and co-immunoprecipitation assays were utilized to discover proteins that interact with AEP. Gastric cancer cell lines were established, in which AEP was overexpressed or knocked out using lentiviral CRISPR. The proliferative abilities of these cell lines in response to chemotherapy agents were evaluated using the Cell Counting Kit-8 method. Gene expression changes in these lines were assessed by real-time polymerase chain reaction and Western blot. RESULTS Patients with low expression of AEP were significantly more likely to have a good prognosis and experience complete response or partial response after treatment with docetaxel/S-1 regimen. Mass spectrum analysis showed that several proteins in the focal adhesion and mitogen-activated protein kinase signaling pathways interacted with AEP. IQGAP1 was confirmed to be one of the proteins interacting with AEP, and its protein level increased when AEP was knocked out. AEP knockout decreased resistance to microtubule inhibitors, including paclitaxel, docetaxel, and T-DM1. The expression levels of MDR1, p-EGFR, p-JNK, p-ERK, and p-Rac1/cdc42 were decreased in AEP knockout gastric cancer cell lines, and inhibitors of both JNK and ERK could block AEP-induced expression of MDR1. CONCLUSION AEP was not only a prognostic factor but also a predictive marker. AEP knockout could inhibit the activity of the EGFR/JNK/ERK signaling pathway and improve sensitivity to microtubule inhibitors through interacting with IQGAP1.
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Affiliation(s)
| | | | | | | | - Hongshan Wang
- General Surgery Department, Zhongshan Hospital, Fudan University, Shanghai, People's Republic of China
| | - Weidong Chen
- General Surgery Department, Zhongshan Hospital, Fudan University, Shanghai, People's Republic of China
| | - Shangmin Zhang
- Pathology Department, Yale School of Medicine, New Haven, CT, USA
| | - Jian Cao
- Pathology Department, Yale School of Medicine, New Haven, CT, USA
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23
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Liu J, Kurella VB, LeCour L, Vanagunas T, Worthylake DK. The IQGAP1 N-Terminus Forms Dimers, and the Dimer Interface Is Required for Binding F-Actin and Calcium-Bound Calmodulin. Biochemistry 2016; 55:6433-6444. [PMID: 27798963 DOI: 10.1021/acs.biochem.6b00745] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
IQGAP1 is a multidomain scaffold protein involved in many cellular processes. We have determined the crystal structure of an N-terminal fragment spanning residues 1-191 (CHDF hereafter) that contains the entire calponin homology domain. The structure of the CHDF is very similar to those of other type 3 calponin homology domains like those from calponin, Vav, and the yeast IQGAP1 ortholog Rng2. However, in the crystal, two CHDF molecules form a "head-to-head" or parallel dimer through mostly hydrophobic interactions. Binding experiments indicate that the CHDF binds to both F-actin and Ca2+/calmodulin, but binding is mutually exclusive. On the basis of the structure, two dimer interface substitutions were introduced. While CHDFL157D disrupts the dimer in gel filtration experiments, oxidized CHDFK161C stabilizes the dimer. These results imply that the CHDF forms the same dimer in solution that is seen in the crystal structure. The disulfide-stabilized dimer displays a reduced level of F-actin binding in sedimentation assays and shows no binding to Ca2+/calmodulin in isothermal titration calorimetry (ITC) experiments, indicating that interface residues are utilized for both binding events. The Calmodulin Target Database predicts that residues 93KK94 are important for CaM binding, and indeed, the 93EE94 double mutation displays a reduced level of binding to Ca2+/calmodulin in ITC experiments. Our results indicate that the CHDF dimer interface is used for both F-actin and Ca2+/calmodulin binding, and the 93KK94 pair, near the interface, is also used for Ca2+/calmodulin binding. These results are also consistent with full-length IQGAP1 forming a parallel homodimer.
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Affiliation(s)
- Jing Liu
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center-New Orleans , 1901 Perdido Street, New Orleans, Louisiana 70112, United States
| | - Vinodh B Kurella
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center-New Orleans , 1901 Perdido Street, New Orleans, Louisiana 70112, United States
| | - Louis LeCour
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center-New Orleans , 1901 Perdido Street, New Orleans, Louisiana 70112, United States
| | - Tomas Vanagunas
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center-New Orleans , 1901 Perdido Street, New Orleans, Louisiana 70112, United States
| | - David K Worthylake
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center-New Orleans , 1901 Perdido Street, New Orleans, Louisiana 70112, United States
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24
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Nouri K, Fansa EK, Amin E, Dvorsky R, Gremer L, Willbold D, Schmitt L, Timson DJ, Ahmadian MR. IQGAP1 Interaction with RHO Family Proteins Revisited: KINETIC AND EQUILIBRIUM EVIDENCE FOR MULTIPLE DISTINCT BINDING SITES. J Biol Chem 2016; 291:26364-26376. [PMID: 27815503 PMCID: PMC5159498 DOI: 10.1074/jbc.m116.752121] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/27/2016] [Indexed: 11/16/2022] Open
Abstract
IQ motif-containing GTPase activating protein 1 (IQGAP1) plays a central role in the physical assembly of relevant signaling networks that are responsible for various cellular processes, including cell adhesion, polarity, and transmigration. The RHO family proteins CDC42 and RAC1 have been shown to mainly interact with the GAP-related domain (GRD) of IQGAP1. However, the role of its RASGAP C-terminal (RGCT) and C-terminal domains in the interactions with RHO proteins has remained obscure. Here, we demonstrate that IQGAP1 interactions with RHO proteins underlie a multiple-step binding mechanism: (i) a high affinity, GTP-dependent binding of RGCT to the switch regions of CDC42 or RAC1 and (ii) a very low affinity binding of GRD and a C terminus adjacent to the switch regions. These data were confirmed by phosphomimetic mutation of serine 1443 to glutamate within RGCT, which led to a significant reduction of IQGAP1 affinity for CDC42 and RAC1, clearly disclosing the critical role of RGCT for these interactions. Unlike CDC42, an extremely low affinity was determined for the RAC1-GRD interaction, suggesting that the molecular nature of IQGAP1 interaction with CDC42 partially differs from that of RAC1. Our study provides new insights into the interaction characteristics of IQGAP1 with RHO family proteins and highlights the complementary importance of kinetic and equilibrium analyses. We propose that the ability of IQGAP1 to interact with RHO proteins is based on a multiple-step binding process, which is a prerequisite for the dynamic functions of IQGAP1 as a scaffolding protein and a critical mechanism in temporal regulation and integration of IQGAP1-mediated cellular responses.
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Affiliation(s)
- Kazem Nouri
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Eyad K Fansa
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Ehsan Amin
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Radovan Dvorsky
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Lothar Gremer
- the Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany.,Forschungszentrum Jülich, ICS-6, 52428 Jülich, Germany
| | - Dieter Willbold
- the Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany.,Forschungszentrum Jülich, ICS-6, 52428 Jülich, Germany
| | - Lutz Schmitt
- the Institute of Biochemistry, Heinrich-Heine University, 40225 Düsseldorf, Germany, and
| | - David J Timson
- the School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, United Kingdom
| | - Mohammad R Ahmadian
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany,
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Socoro-Yuste N, Dagher MC, Gonzalez De Peredo A, Mondet J, Zaccaria A, Roux Dalvai F, Plo I, Cahn JY, Mossuz P. Ph(-) myeloproliferative neoplasm red blood cells display deregulation of IQGAP1-Rho GTPase signaling depending on CALR/JAK2 status. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2758-2765. [PMID: 27566291 DOI: 10.1016/j.bbamcr.2016.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 12/26/2022]
Abstract
Besides genetic abnormalities in MPN patients, several studies have reported alterations in protein expression that could contribute towards the clinical phenotype. However, little is known about protein modifications in Ph- MPN erythrocytes. In this context, we used a quantitative mass spectrometry proteomics approach to study the MPN erythrocyte proteome. LC-MS/MS (LTQ Orbitrap) analysis led to the identification of 51 and 86 overexpressed proteins in Polycythemia Vera and Essential Thrombocythemia respectively, compared with controls. Functional comparison using pathway analysis software showed that the Rho GTPase family signaling pathways were deregulated in MPN patients. In particular, IQGAP1 was significantly overexpressed in MPNs compared with controls. Additionally, Western-blot analysis not only confirmed IQGAP1 overexpression, but also showed that IQGAP1 levels depended on the patient's genotype. Moreover, we found that in JAK2V617F patients IQGAP1 could bind RhoA, Rac1 and Cdc42 and consequently recruit activated GTP-Rac1 and the cytoskeleton motility protein PAK1. In CALR(+) patients, IQGAP1 was not overexpressed but immunoprecipitated with RhoGDI. In JAK2V617F transduced Ba/F3 cells we confirmed JAK2 inhibitor-sensitive overexpression of IQGAP1/PAK1. Altogether, our data demonstrated alterations of IQGAP1/Rho GTPase signaling in MPN erythrocytes dependent on JAK2/CALR status, reinforcing the hypothesis that modifications in erythrocyte signaling pathways participate in Ph- MPN pathogenesis.
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Affiliation(s)
- Nuria Socoro-Yuste
- TheREx Team "Thérapeutique recombinante expérimentale", TIMC-IMAG Laboratory, "Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications de Grenoble", UMR, UJF, CNRS 5525, University of Grenoble Alpes, France.
| | - Marie-Claire Dagher
- TheREx Team "Thérapeutique recombinante expérimentale", TIMC-IMAG Laboratory, "Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications de Grenoble", UMR, UJF, CNRS 5525, University of Grenoble Alpes, France
| | - Anne Gonzalez De Peredo
- Plateforme Protéomique de la Génopole Toulouse Midi-Pyrénées, Institut de Pharmacologie et de Biologie Structurale, CNRS, UMR, 5089 Toulouse, France
| | - Julie Mondet
- TheREx Team "Thérapeutique recombinante expérimentale", TIMC-IMAG Laboratory, "Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications de Grenoble", UMR, UJF, CNRS 5525, University of Grenoble Alpes, France
| | - Affif Zaccaria
- Department of clinical proteomics, University of Geneva, Switzerland
| | - Florence Roux Dalvai
- Plateforme Protéomique de la Génopole Toulouse Midi-Pyrénées, Institut de Pharmacologie et de Biologie Structurale, CNRS, UMR, 5089 Toulouse, France
| | - Isabelle Plo
- INSERM, UMR1170, Gustave Roussy, Université Paris-Sud, Villejuif, France
| | - Jean Yves Cahn
- TheREx Team "Thérapeutique recombinante expérimentale", TIMC-IMAG Laboratory, "Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications de Grenoble", UMR, UJF, CNRS 5525, University of Grenoble Alpes, France; Clinique Universitaire d'Hématologie, Grenoble Alpes University Hospital, France
| | - Pascal Mossuz
- TheREx Team "Thérapeutique recombinante expérimentale", TIMC-IMAG Laboratory, "Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications de Grenoble", UMR, UJF, CNRS 5525, University of Grenoble Alpes, France; Laboratoire d'Hématologie cellulaire, Institut de Biologie et Pathologie, Grenoble Alpes University Hospital, France
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26
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Choi S, Anderson RA. IQGAP1 is a phosphoinositide effector and kinase scaffold. Adv Biol Regul 2015; 60:29-35. [PMID: 26554303 DOI: 10.1016/j.jbior.2015.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 01/16/2023]
Abstract
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.
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Affiliation(s)
- Suyong Choi
- University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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Watanabe T, Wang S, Kaibuchi K. IQGAPs as Key Regulators of Actin-cytoskeleton Dynamics. Cell Struct Funct 2015; 40:69-77. [PMID: 26051604 DOI: 10.1247/csf.15003] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The actin-cytoskeleton plays a critical role in various biological processes, including cell migration, development, tissue remodeling, and memory formation. Both extracellular and intracellular signals regulate reorganization of the actin-cytoskeleton to modulate tissue architecture and cellular morphology in a spatiotemporal manner. Since the discovery that activation of Rho family GTPases induces actin-cytoskeleton reorganization, the mode of action of Rho family GTPases has been extensively studied and individual effectors have been characterized. The actin-binding protein IQGAP1 was identified as an effector of Rac and Cdc42 and is the founding member of the IQGAP family with two additional isoforms. The IQGAP family shows conserved domain organization, and each member displays a specific expression pattern in mammalian tissues. IQGAPs regulate the actin-cytoskeleton alone and with their binding partners, thereby controlling diverse cellular processes, such as cell migration and adhesion. Here, we introduce IQGAPs as an actin-cytoskeleton regulator.
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Affiliation(s)
- Takashi Watanabe
- Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine
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Choi S, Thapa N, Tan X, Hedman AC, Anderson RA. PIP kinases define PI4,5P₂signaling specificity by association with effectors. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1851:711-23. [PMID: 25617736 PMCID: PMC4380618 DOI: 10.1016/j.bbalip.2015.01.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/14/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI4,5P₂) is an essential lipid messenger with roles in all eukaryotes and most aspects of human physiology. By controlling the targeting and activity of its effectors, PI4,5P₂modulates processes, such as cell migration, vesicular trafficking, cellular morphogenesis, signaling and gene expression. In cells, PI4,5P₂has a much higher concentration than other phosphoinositide species and its total content is largely unchanged in response to extracellular stimuli. The discovery of a vast array of PI4,5P₂ binding proteins is consistent with data showing that the majority of cellular PI4,5P₂is sequestered. This supports a mechanism where PI4,5P₂functions as a localized and highly specific messenger. Further support of this mechanism comes from the de novo synthesis of PI4,5P₂which is often linked with PIP kinase interaction with PI4,5P₂effectors and is a mechanism to define specificity of PI4,5P₂signaling. The association of PI4,5P₂-generating enzymes with PI4,5P₂effectors regulate effector function both temporally and spatially in cells. In this review, the PI4,5P₂effectors whose functions are tightly regulated by associations with PI4,5P₂-generating enzymes will be discussed. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Narendra Thapa
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Xiaojun Tan
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Andrew C Hedman
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA; Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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Lian ATY, Hains PG, Sarcevic B, Robinson PJ, Chircop M. IQGAP1 is associated with nuclear envelope reformation and completion of abscission. Cell Cycle 2015; 14:2058-74. [PMID: 25928398 DOI: 10.1080/15384101.2015.1044168] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The final stage of mitosis is cytokinesis, which results in 2 independent daughter cells. Cytokinesis has 2 phases: membrane ingression followed by membrane abscission. IQGAP1 is a scaffold protein that interacts with proteins implicated in mitosis, including F-actin, myosin and CaM. IQGAP1 in yeast recruits actin and myosin II filaments to the contractile ring for membrane ingression. In contrast, we show that mammalian IQGAP1 is not required for ingression, but coordinates nuclear pore complex (NPC) reassembly and completion of abscission. Depletion of IQGAP1 disrupts Nup98 and mAb414 nuclear envelope localization and delays abscission timing. IQGAP1 phosphorylation increases 15-fold upon mitotic entry at S86, S330 and T1434, with the latter site being targeted by CDK2/Cyclin A and CDK1/Cyclin A/B in vitro. Expressing the phospho-deficient mutant IQGAP1-S330A impairs NPC reassembly in cells undergoing abscission. Thus, mammalian IQGAP1 functions later in mitosis than its yeast counterpart to regulate nuclear pore assembly in a S330 phosphorylation-dependent manner during the abscission phase of cytokinesis.
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Affiliation(s)
- Audrey T Y Lian
- a Children's Medical Research Institute; The University of Sydney ; Westmead , New South Wales , Australia
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30
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Xia FD, Wang ZL, Chen HX, Huang Y, Li JD, Wang ZM, Li XY. Differential expression of IQGAP1/2 in Hepatocellular carcinoma and its relationship with clinical outcomes. Asian Pac J Cancer Prev 2015; 15:4951-6. [PMID: 24998570 DOI: 10.7314/apjcp.2014.15.12.4951] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To investigate IQGAP1 and IQGAP2 expression in hepatocellular carcinoma (HCC) and itsassociation with HCC clinicopathological characteristics and survival outcomes. METHODS IQGAP1 and IQGAP2 mRNA and protein were measured in HCC tissues, para-tumor tissues and normal tissues by RT-PCR and Western blotting. We further examined 150 HCC samples with adjacent para-tumor tissues and 11 normal specimens by immunohistochemistry to evaluate the correlation of IQGAP1 and IQGAP2 with clinicopathological features and prognosis. RESULTS IQGAP1 mRNA and protein were up-regulated while IQGAP2 mRNA and protein were down-regulated in human HCC tissues compared with para-tumor and normal liver tissues (p<0.05). IQGAP1 expression was higher in primary HCC (122/150, 81.3%) than matched adjacent tissues (30/150, 20%, p<0.001), whereas IQGAP2 was lower (31/150, 20.7% as compared to 112/150, 74.7%, P<0.001). Positive IQGAP1 expression correlated with larger tumor size (p=0.002), advanced TNM stage (p=0.002) and tumor differentiation (III and IV, p=0.034). Negative IQGAP2 expression was significantly associated with larger tumor size (p=0.009), multicentric tumor occurrence (p=0.01), advanced TNM stage (0.009) and tumor differentiation (III and IV, p=0.020). Survival analysis revealed that patients with either IQGAP1+ or IQGAP2- tumors had significantly reduced disease-free survival (p<0.001 and 0.006 respectively) and overall survival (p<0.001 for both). Multivariate analysis showed that IQGAP1/2 switch was an independent prognosis factor for disease-free survival (HR=2.824) and overall survival (HR=2.189). CONCLUSION Positive IQGAP1 and negative IQGAP2 expression were closely correlated with tumor progression and could be used as adjunctive biomarkers to improve prognostication for HCC patients.
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Affiliation(s)
- Fa-Da Xia
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha, China E-mail :
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31
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Abel AM, Schuldt KM, Rajasekaran K, Hwang D, Riese MJ, Rao S, Thakar MS, Malarkannan S. IQGAP1: insights into the function of a molecular puppeteer. Mol Immunol 2015; 65:336-49. [PMID: 25733387 DOI: 10.1016/j.molimm.2015.02.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/09/2015] [Accepted: 02/09/2015] [Indexed: 02/06/2023]
Abstract
The intracellular spatiotemporal organization of signaling events is critical for normal cellular function. In response to environmental stimuli, cells utilize highly organized signaling pathways that are subject to multiple layers of regulation. However, the molecular mechanisms that coordinate these complex processes remain an enigma. Scaffolding proteins (scaffolins) have emerged as critical regulators of signaling pathways, many of which have well-described functions in immune cells. IQGAP1, a highly conserved cytoplasmic scaffold protein, is able to curb, compartmentalize, and coordinate multiple signaling pathways in a variety of cell types. IQGAP1 plays a central role in cell-cell interaction, cell adherence, and movement via actin/tubulin-based cytoskeletal reorganization. Evidence also implicates IQGAP1 as an essential regulator of the MAPK and Wnt/β-catenin signaling pathways. Here, we summarize the recent advances on the cellular and molecular biology of IQGAP1. We also describe how this pleiotropic scaffolin acts as a true molecular puppeteer, and highlight the significance of future research regarding the role of IQGAP1 in immune cells.
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Affiliation(s)
- Alex M Abel
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kristina M Schuldt
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kamalakannan Rajasekaran
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - David Hwang
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Matthew J Riese
- Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sridhar Rao
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Monica S Thakar
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Hedman AC, Smith JM, Sacks DB. The biology of IQGAP proteins: beyond the cytoskeleton. EMBO Rep 2015; 16:427-46. [PMID: 25722290 DOI: 10.15252/embr.201439834] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/07/2015] [Indexed: 01/02/2023] Open
Abstract
IQGAP scaffold proteins are evolutionarily conserved in eukaryotes and facilitate the formation of complexes that regulate cytoskeletal dynamics, intracellular signaling, and intercellular interactions. Fungal and mammalian IQGAPs are implicated in cytokinesis. IQGAP1, IQGAP2, and IQGAP3 have diverse roles in vertebrate physiology, operating in the kidney, nervous system, cardio-vascular system, pancreas, and lung. The functions of IQGAPs can be corrupted during oncogenesis and are usurped by microbial pathogens. Therefore, IQGAPs represent intriguing candidates for novel therapeutic agents. While modulation of the cytoskeletal architecture was initially thought to be the primary function of IQGAPs, it is now clear that they have roles beyond the cytoskeleton. This review describes contributions of IQGAPs to physiology at the organism level.
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Affiliation(s)
- Andrew C Hedman
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Jessica M Smith
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD, USA
| | - David B Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD, USA
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Liu Y, Liang W, Yang Y, Pan Y, Yang Q, Chen X, Singhal PC, Ding G. IQGAP1 regulates actin cytoskeleton organization in podocytes through interaction with nephrin. Cell Signal 2015; 27:867-77. [PMID: 25652011 DOI: 10.1016/j.cellsig.2015.01.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 01/27/2015] [Indexed: 10/24/2022]
Abstract
Increasing data has shown that the cytoskeletal reorganization of podocytes is involved in the onset of proteinuria and the progression of glomerular disease. Nephrin behaves as a signal sensor of the slit diaphragm to transmit cytoskeletal signals to maintain the unique structure of podocytes. However, the nephrin signaling cascade deserves further study. IQGAP1 is a scaffolding protein with the ability to regulate cytoskeletal organization. It is hypothesized that IQGAP1 contributes to actin reorganization in podocytes through interaction with nephrin. IQGAP1 expression and IQGAP1-nephrin colocalization in glomeruli were progressively decreased and then gradually recovered in line with the development of foot process fusion and proteinuria in puromycin aminonucleoside-injected rats. In cultured human podocytes, puromycin aminonucleoside-induced disruption of F-actin and disorders of migration and spreading were aggravated by IQGAP1 siRNA, and these effects were partially restored by a wild-type IQGAP1 plasmid. Furthermore, the cytoskeletal disorganization stimulated by cytochalasin D in COS7 cells was recovered by cotransfection with wild-type IQGAP1 and nephrin plasmids but was not recovered either by single transfection of the wild-type IQGAP1 plasmid or by cotransfection of mutant IQGAP1 [△1443(S→A)] and wild-type nephrin plasmids. Co-immunoprecipitation analysis using lysates of COS7 cells overexpressing nephrin and each derivative-domain molecule of IQGAP1 demonstrated that the poly-proline binding domain and RasGAP domain in the carboxyl terminus of IQGAP1 are the target modules that interact with nephrin. Collectively, these findings showed that activated IQGAP1, as an intracellular partner of nephrin, is involved in actin cytoskeleton organization and functional regulation of podocytes.
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Affiliation(s)
- Yipeng Liu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China; Department of Nephrology, Qianfoshan Hospital, Shandong University, Jinan, China
| | - Wei Liang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yingjie Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yangbin Pan
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Qian Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xinghua Chen
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Pravin C Singhal
- Renal Molecular Research Laboratory, Feinstein Institute for Medical Research, Hofstra North Shore LIJ Medical School, Great Neck, NY, USA
| | - Guohua Ding
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China.
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Amarachintha SP, Ryan KJ, Cayer M, Boudreau NS, Johnson NM, Heckman CA. Effect of Cdc42 domains on filopodia sensing, cell orientation, and haptotaxis. Cell Signal 2014; 27:683-93. [PMID: 25435426 DOI: 10.1016/j.cellsig.2014.11.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 11/21/2014] [Indexed: 11/17/2022]
Abstract
Filopodia are sensors which, along with microtubules, regulate the persistence of locomotion. To determine whether protrusions were involved in sensing adhesion, epithelial cells were cultured on platinum and tantalum gradients. Protrusions were defined by an unbiased statistical method of classification as factors 4 (filopodia), 5 (mass distribution), and 7 (nascent neurites). When the prevalence of protrusions was measured in zones of high (H), middle (M), and low (L) adhesiveness, the main differences were in factor 4. Its values were highest at H and declined at M and L regardless of the gradient composition. The significance of the differences was enhanced when T (top/adhesive end) and B (bottom/nonadhesive end) sides of cells were analyzed separately. Since information about sidedness increased the statistical power of the test, this result suggested that cells pointed more filopodia toward the adhesive end. Trends occurred in factors 5 and 7 only when conditions allowed for a marked trend in factor 4. The data showed that gradient sensing is proportional to the prevalence of filopodia, and filopodia are the only protrusions engaged in comparing adhesiveness across a cell. The probability (P) of the significance of a trend was then used to determine how cells sense the gradient. Binding peptides (BPs) were introduced representing sequences critical for Cdc42 docking on a specific partner. BPs for IQGAP (IQ(calmodulin-binding domain)-containing GTPase-activating protein) and ACK (Cdc42-associated kinase) reduced factor 4 values and prevented cell orientation on the gradient. Micrographs showed attenuated or stubby filopodia. These effectors may be implicated in gradient sensing. Another IQGAP BP increased filopodia prevalence and enhanced orientation on the gradient (P<0.00015). A Wiskott-Aldrich syndrome protein (WASP) BP had no effect. When sensing and orientation were abolished, they both failed at the level of filopodia, indicating that filopodia are both sensors and implementers of signals transduced by adhesion.
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Affiliation(s)
- Surya P Amarachintha
- Center for Microscopy and Microanalysis, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Kenneth J Ryan
- Department of Applied Statistics and Operations Research, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Marilyn Cayer
- Center for Microscopy and Microanalysis, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Nancy S Boudreau
- Department of Applied Statistics and Operations Research, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Nathan M Johnson
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Carol A Heckman
- Center for Microscopy and Microanalysis, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States; Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
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Filić V, Marinović M, Faix J, Weber I. The IQGAP-related protein DGAP1 mediates signaling to the actin cytoskeleton as an effector and a sequestrator of Rac1 GTPases. Cell Mol Life Sci 2014; 71:2775-85. [PMID: 24664433 PMCID: PMC11113302 DOI: 10.1007/s00018-014-1606-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/26/2014] [Accepted: 03/10/2014] [Indexed: 11/24/2022]
Abstract
Proteins are typically categorized into protein families based on their domain organization. Yet, evolutionarily unrelated proteins can also be grouped together according to their common functional roles. Sequestering proteins constitute one such functional class, acting as macromolecular buffers and serving as an intracellular reservoir ready to release large quantities of bound proteins or other molecules upon appropriate stimulation. Another functional protein class comprises effector proteins, which constitute essential components of many intracellular signal transduction pathways. For instance, effectors of small GTP-hydrolases are activated upon binding a GTP-bound GTPase and thereupon participate in downstream interactions. Here we describe a member of the IQGAP family of scaffolding proteins, DGAP1 from Dictyostelium, which unifies the roles of an effector and a sequestrator in regard to the small GTPase Rac1. Unlike classical effectors, which bind their activators transiently leading to short-lived signaling complexes, interaction between DGAP1 and Rac1-GTP is stable and induces formation of a complex with actin-bundling proteins cortexillins at the back end of the cell. An oppositely localized Rac1 effector, the Scar/WAVE complex, promotes actin polymerization at the cell front. Competition between DGAP1 and Scar/WAVE for the common activator Rac1-GTP might provide the basis for the oscillatory re-polarization typically seen in randomly migrating Dictyostelium cells. We discuss the consequences of the dual roles exerted by DGAP1 and Rac1 in the regulation of cell motility and polarity, and propose that similar signaling mechanisms may be of general importance in regulating spatiotemporal dynamics of the actin cytoskeleton by small GTPases.
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Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Maja Marinović
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Jan Faix
- Hannover Medical School, Institute for Biophysical Chemistry, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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G-protein-coupled receptor GPR161 is overexpressed in breast cancer and is a promoter of cell proliferation and invasion. Proc Natl Acad Sci U S A 2014; 111:4191-6. [PMID: 24599592 DOI: 10.1073/pnas.1320239111] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Triple-negative breast cancer (TNBC) accounts for 20% of breast cancer in women and lacks an effective targeted therapy. Therefore, finding common vulnerabilities in these tumors represents an opportunity for more effective treatment. Despite the growing appreciation of G-protein-coupled receptor (GPCR)-mediated signaling in cancer pathogenesis, very little is known about the role GPCRs play in TNBC. Using genomic information of human breast cancer, we have discovered that the orphan GPCR, G-protein-coupled receptor 161 (GPR161) is overexpressed specifically in TNBC and correlates with poor prognosis. Knockdown of GPR161 impairs proliferation of human basal breast cancer cell lines. Overexpression of GPR161 in human mammary epithelial cells increases cell proliferation, migration, intracellular accumulation of E-cadherin, and formation of multiacinar structures in 3D culture. GPR161 forms a signaling complex with the scaffold proteins β-arrestin 2 and Ile Gln motif containing GTPase Activating Protein 1, a regulator of mammalian target of rapamycin complex 1 and E-cadherin. Consistently, GPR161 amplified breast tumors and cells overexpressing GPR161 activate mammalian target of rapamycin signaling and decrease Ile Gln motif containing GTPase Activating Protein 1 phosphorylation. Thus, we identify the orphan GPCR, GPR161, as an important regulator and a potential drug target for TNBC.
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Choi S, Thapa N, Hedman AC, Li Z, Sacks DB, Anderson RA. IQGAP1 is a novel phosphatidylinositol 4,5 bisphosphate effector in regulation of directional cell migration. EMBO J 2013; 32:2617-30. [PMID: 23982733 DOI: 10.1038/emboj.2013.191] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/29/2013] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylinositol 4,5 bisphosphate (PIP₂) is a key lipid messenger for regulation of cell migration. PIP₂ modulates many effectors, but the specificity of PIP₂ signalling can be defined by interactions of PIP₂-generating enzymes with PIP₂ effectors. Here, we show that type Iγ phosphatidylinositol 4-phosphate 5-kinase (PIPKIγ) interacts with the cytoskeleton regulator, IQGAP1, and modulates IQGAP1 function in migration. We reveal that PIPKIγ is required for IQGAP1 recruitment to the leading edge membrane in response to integrin or growth factor receptor activation. Moreover, IQGAP1 is a PIP₂ effector that directly binds PIP₂ through a polybasic motif and PIP₂ binding activates IQGAP1, facilitating actin polymerization. IQGAP1 mutants that lack PIPKIγ or PIP₂ binding lose the ability to control directional cell migration. Collectively, these data reveal a synergy between PIPKIγ and IQGAP1 in the control of cell migration.
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Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
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Osman MA, Bloom GS, Tagoe EA. Helicobacter pylori-induced alteration of epithelial cell signaling and polarity: a possible mechanism of gastric carcinoma etiology and disparity. Cytoskeleton (Hoboken) 2013; 70:349-59. [PMID: 23629919 DOI: 10.1002/cm.21114] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 03/04/2013] [Accepted: 04/24/2013] [Indexed: 12/11/2022]
Abstract
Gastric cancer, a disease of disparity associated with Helicobacter pylori (H. pylori) infection, is the world's second leading cause of cancer deaths. The pathogen H. pylori target the epithelial adhesion receptors, E-cadherin, and β1-integrin, to modulate the host cytoskeleton via disruption of the epithelial cell polarity necessary for maintaining the infection, but how this leads to the development of the carcinoma is widely unclear. While Rho family GTPases' signaling to the cytoskeleton and these receptors is required for initiating and maintaining the infection, the responsible effectors, and how they might influence the etiology of the carcinomas are currently unknown. Here we discuss the potential role of the Cdc42-IQGAP1 axis, a negative regulator of the tumor suppressors E-cadherin and β1-integrin, as a potential driver of H. pylori-induced gastric carcinoma and propose avenues for addressing its disparity. Chronic dysfunction of the IQGAP1-signaling pathway, resulting from H. pylori-induced disruption of cell polarity, can explain the pathogenesis of the carcinoma, at least, in subsets of infected population, and thus could provide a potential means for personalized medicine.
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Affiliation(s)
- Mahasin A Osman
- Department of Molecular Pharmacology, Physiology and Biotechnology, Warren Alpert Medical School, Brown University, Providence, RI 02912, USA.
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Osman MA, Sarkar FH, Rodriguez-Boulan E. A molecular rheostat at the interface of cancer and diabetes. Biochim Biophys Acta Rev Cancer 2013; 1836:166-76. [PMID: 23639840 DOI: 10.1016/j.bbcan.2013.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 04/23/2013] [Indexed: 12/17/2022]
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.
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Affiliation(s)
- Mahasin A Osman
- Warren Alpert Medical School, Division of Biology and Medicine, Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA.
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Garcia-Cattaneo A, Braga VMM. Hold on tightly: how to keep the local activation of small GTPases. Cell Adh Migr 2013; 7:283-7. [PMID: 23590879 DOI: 10.4161/cam.24646] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Signaling regulated by Rho small GTPases plays a pivotal role in cell migration, cell attachment to substratum or to their neighbors among other functions. Concerted efforts have focused on understanding how different GTPases are activated by specific stimuli and which regulator is responsible for the spatio-temporal control of their activity at particular intracellular sites. We have recently described the role of a scaffold protein, Ajuba, in adherens junction maintenance via direct stabilization of activated small GTPase Rac1 at cell-cell contacts. Ajuba binds to both active and inactive forms of Rac1. Upon junction formation, Rac1 activation initiates a positive feedback loop leading to Ajuba phosphorylation and Ajuba-mediated retention of activated Rac1 at junctions. Thus, cytoskeletal proteins may have a dual role to provide a scaffolding platform and dynamically modulate small GTPases function at a specific place, irrespective of their ability to interact with active and inactive forms. Here we discuss similar mechanisms via which cytoskeletal proteins can facilitate cellular processes downstream of Rho proteins by increasing their affinity to activated GTPases.
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Affiliation(s)
- Alejandra Garcia-Cattaneo
- Molecular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
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41
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Kozlova I, Ruusala A, Voytyuk O, Skandalis SS, Heldin P. IQGAP1 regulates hyaluronan-mediated fibroblast motility and proliferation. Cell Signal 2012; 24:1856-62. [DOI: 10.1016/j.cellsig.2012.05.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 05/14/2012] [Indexed: 10/28/2022]
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Chen X, Zhao X, Abeyweera TP, Rotenberg SA. Analysis of substrates of protein kinase C isoforms in human breast cells by the traceable kinase method. Biochemistry 2012; 51:7087-97. [PMID: 22897107 DOI: 10.1021/bi300999c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A previous report [Abeyweera, T. P., and Rotenberg, S. A. (2007) Biochemistry 46, 2364-2370] described the application of the traceable kinase method in identifying substrates of protein kinase Cα (PKC-α) in nontransformed human breast MCF-10A cells. Here, a nonradioactive variation of this method compared the phosphoprotein profiles of three traceable PKC isoforms (α, δ, and ζ) for the purpose of identifying novel, isoform-selective substrates. Each FLAG-tagged traceable kinase was expressed and co-immunoprecipitated along with high-affinity substrates. The isolated kinase and its associated substrates were subjected to an in vitro phosphorylation reaction with traceable kinase-specific N(6)-phenyl-ATP, and the resulting phosphoproteins were analyzed by Western blotting with an antibody that recognizes the phosphorylated PKC consensus site. Phosphoprotein profiles generated by PKC-α and -δ were similar and differed markedly from that of PKC-ζ. Mass spectrometry of selected bands revealed known PKC substrates and several potential substrates that included the small GTPase-associated Cdc42 effector protein-4 (CEP4). Of those potential substrates tested, only CEP4 was phosphorylated by pure PKC-α, -δ, and -ζ isoforms in vitro, and by endogenous PKC isoforms in MCF-10A cells treated with DAG-lactone, a membrane permeable PKC activator. Under these conditions, the stoichiometry of CEP4 phosphorylation was 3.2 ± 0.5 (moles of phospho-CEP4 per mole of CEP4). Following knockdown with isoform-specific shRNA-encoding plasmids, the level of phosphorylation of CEP4 was substantially decreased in response to silencing of each of the three isoforms (PKC-α, -δ, and -ζ), whereas testing of kinase-dead mutants supported a role for only PKC-α and -δ in CEP4 phosphorylation. These findings identify CEP4 as a novel intracellular PKC substrate that is phosphorylated by multiple PKC isoforms.
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Affiliation(s)
- Xiangyu Chen
- Department of Chemistry and Biochemistry, Queens College, The City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367, USA
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43
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Fang X, Wang C, Balgley BM, Zhao K, Wang W, He F, Weil RJ, Lee CS. Targeted tissue proteomic analysis of human astrocytomas. J Proteome Res 2012; 11:3937-46. [PMID: 22794670 DOI: 10.1021/pr300303t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complicating proteomic analysis of whole tissues is the obvious problem of cell heterogeneity in tissues, which often results in misleading or confusing molecular findings. Thus, the coupling of tissue microdissection for tumor cell enrichment with capillary isotachophoresis-based selective analyte concentration not only serves as a synergistic strategy to characterize low abundance proteins, but it can also be employed to conduct comparative proteomic studies of human astrocytomas. A set of fresh frozen brain biopsies were selectively microdissected to provide an enriched, high quality, and reproducible sample of tumor cells. Despite sharing many common proteins, there are significant differences in the protein expression level among different grades of astrocytomas. A large number of proteins, such as plasma membrane proteins EGFR and Erbb2, are up-regulated in glioblastoma. Besides facilitating the prioritization of follow-on biomarker selection and validation, comparative proteomics involving measurements in changes of pathways are expected to reveal the molecular relationships among different pathological grades of gliomas and potential molecular mechanisms that drive gliomagenesis.
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Affiliation(s)
- Xueping Fang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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44
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Elliott SF, Allen G, Timson DJ. Biochemical analysis of the interactions of IQGAP1 C-terminal domain with CDC42. World J Biol Chem 2012; 3:53-60. [PMID: 22451851 PMCID: PMC3312201 DOI: 10.4331/wjbc.v3.i3.53] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 01/31/2012] [Accepted: 02/07/2012] [Indexed: 02/05/2023] Open
Abstract
AIM: To understand the interaction of human IQGAP1 and CDC42, especially the effects of phosphorylation and a cancer-associated mutation.
METHODS: Recombinant CDC42 and a novel C-terminal fragment of IQGAP1 were expressed in, and purified from, Escherichia coli. Site directed mutagenesis was used to create coding sequences for three phosphomimicking variants (S1441E, S1443D and S1441E/S1443D) and to recapitulate a cancer-associated mutation (M1231I). These variant proteins were also expressed and purified. Protein-protein crosslinking using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide was used to investigate interactions between the C-terminal fragment and CDC42. These interactions were quantified using surface plasmon resonance measurements. Molecular modelling was employed to make predictions about changes to the structure and flexibility of the protein which occur in the cancer-associated variant.
RESULTS: The novel, C-terminal region of human IQGAP1 (residues 877-1558) is soluble following expression and purification. It is also capable of binding to CDC42, as judged by crosslinking experiments. Interaction appears to be strongest in the presence of added GTP. The three phosphomimicking mutants had different affinities for CDC42. S1441E had an approximately 200-fold reduction in affinity compared to wild type. This was caused largely by a dramatic reduction in the association rate constant. In contrast, both S1443D and the double variant S1441E/S1443D had similar affinities to the wild type. The cancer-associated variant, M1231I, also had a similar affinity to wild type. However, in the case of this variant, both the association and dissociation rate constants were reduced approximately 10-fold. Molecular modelling of the M1231I variant, based on the published crystal structure of part of the C-terminal region, revealed no gross structural changes compared to wild type (root mean square deviation of 0.564 Å over 5556 equivalent atoms). However, predictions of the flexibility of the polypeptide backbone suggested that some regions of the variant protein had greatly increased rigidity compared to wild type. One such region is a loop linking the proposed CDC42 binding site with the helix containing the altered residue. It is suggested that this increase in rigidity is responsible for the observed changes in association and dissociation rate constants.
CONCLUSION: The consequences of introducing negative charge at Ser-1441 or Ser-1443 in IQGAP1 are different. The cancer-associated variant M1231I exerts its effects partly by rigidifying the protein.
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Affiliation(s)
- Sarah F Elliott
- Sarah F Elliott, George Allen, David J Timson, School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, Belfast, BT9 7BL, United Kingdom
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IQGAP Family Members in Yeast, Dictyostelium, and Mammalian Cells. Int J Cell Biol 2012; 2012:894817. [PMID: 22505937 PMCID: PMC3296274 DOI: 10.1155/2012/894817] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/06/2011] [Accepted: 10/23/2011] [Indexed: 01/04/2023] Open
Abstract
IQGAPs are a family of scaffolding proteins with multiple domains, named for the IQ motifs and GTPase activating protein (GAP) related domains. Despite their GAP homology, IQGAP proteins act as effectors for GTP-bound GTPases of the Ras superfamily and do not stimulate GTP hydrolysis. IQGAPs are found in eukaryotic cells from yeast to human, and localize to actin-containing structures such as lamellipodia, membrane ruffles, cell-cell adhesions, phagocytic cups, and the actomyosin ring formed during cytokinesis. Mammalian IQGAPs also act as scaffolds for signaling pathways. IQGAPs perform their myriad functions through association with a large number of proteins including filamentous actin (F-actin), GTPases, calcium-binding proteins, microtubule binding proteins, kinases, and receptors. The focus of this paper is on recent studies describing new binding partners, mechanisms of regulation, and biochemical and physiological functions of IQGAPs in yeast, amoeba, and mammalian cells.
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46
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Tekletsadik YK, Sonn R, Osman MA. A conserved role of IQGAP1 in regulating TOR complex 1. J Cell Sci 2012; 125:2041-52. [PMID: 22328503 DOI: 10.1242/jcs.098947] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Defining the mechanisms that control cell growth and division is crucial to understanding cell homeostasis, which impacts human diseases such as cancer and diabetes. IQGAP1, a widely conserved effector and/or regulator of the GTPase CDC42, is a putative oncoprotein that controls cell proliferation; however, its mechanism in tumorigenesis is unknown. The mechanistic target of rapamycin (mTOR) pathway, the center of cell growth control, is commonly activated in human cancers, but has proved to be an ineffective clinical target because of an incomplete understanding of its mechanisms in cell growth inhibition. Using complementary studies in yeast and mammalian cells, we examined a potential role for IQGAP1 in regulating the negative feedback loop (NFL) of mTOR complex 1 (mTORC1) that controls cell growth. Two-hybrid screens identified the yeast TORC1-specific subunit Tco89p as an Iqg1p-binding partner, sharing roles in rapamycin-sensitive growth, axial-bud-site selection and cytokinesis, thus coupling cell growth and division. Mammalian IQGAP1 binds mTORC1 and Akt1 and in response to epidermal growth factor (EGF), cells expressing the mTORC1-Akt1-binding region (IQGAP1(IR-WW)) contained attenuated phosphorylated ERK1/2 (ERK1/2-P) activity and inactive glycogen synthase kinase 3α/β (GSK3α/β), which control apoptosis. Interestingly, these cells displayed a high level of Akt1 S473-P, but an attenuated level of the mTORC1-dependent kinase S6K1 T389-P and induced mTORC1-Akt1- and EGF-dependent transformed phenotypes. Moreover, IQGAP1 appears to influence cell abscission and its activity is elevated in carcinoma cell lines. These findings support the hypothesis that IQGAP1 acts upstream on the mTORC1-S6K1→Akt1 NFL and downstream of it, to couple cell growth and division, and thus like a rheostat, regulates cell homeostasis, dysregulation of which leads to tumorigenesis or other diseases. These results could have implications for the development of the next generation of anticancer therapeutics.
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Affiliation(s)
- Yemsrach K Tekletsadik
- Institute for Biotechnology and Life Sciences, Cornell University, Ithaca, NY 14853-2703, USA
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47
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Filić V, Marinović M, Faix J, Weber I. A dual role for Rac1 GTPases in the regulation of cell motility. J Cell Sci 2012; 125:387-98. [PMID: 22302991 DOI: 10.1242/jcs.089680] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rac proteins are the only canonical Rho family GTPases in Dictyostelium, where they act as key regulators of the actin cytoskeleton. To monitor the dynamics of activated Rac1 in Dictyostelium cells, a fluorescent probe was developed that specifically binds to the GTP-bound form of Rac1. The probe is based on the GTPase-binding domain (GBD) from PAK1 kinase, and was selected on the basis of yeast two-hybrid, GST pull-down and fluorescence resonance energy transfer assays. The PAK1 GBD localizes to leading edges of migrating cells and to endocytotic cups. Similarly to its role in vertebrates, activated Rac1 therefore appears to control de novo actin polymerization at protruding regions of the Dictyostelium cell. Additionally, we found that the IQGAP-related protein DGAP1, which sequesters active Rac1 into a quaternary complex with actin-binding proteins cortexillin I and cortexillin II, localizes to the trailing regions of migrating cells. Notably, PAK1 GBD and DGAP1, which both bind to Rac1-GTP, display mutually exclusive localizations in cell migration, phagocytosis and cytokinesis, and opposite dynamics of recruitment to the cell cortex upon stimulation with chemoattractants. Moreover, cortical localization of the PAK1 GBD depends on the integrity of the actin cytoskeleton, whereas cortical localization of DGAP1 does not. Taken together, these results imply that Rac1 GTPases play a dual role in regulation of cell motility and polarity in Dictyostelium.
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Affiliation(s)
- Vedrana Filić
- Ruder Bošković Institute, Division of Molecular Biology, Bijenička 54, HR-10000 Zagreb, Croatia
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48
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Rogers LD, Brown NF, Fang Y, Pelech S, Foster LJ. Phosphoproteomic analysis of Salmonella-infected cells identifies key kinase regulators and SopB-dependent host phosphorylation events. Sci Signal 2012; 4:rs9. [PMID: 21934108 DOI: 10.1126/scisignal.2001668] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Salmonella enterica is a bacterial pathogen that causes gastroenteritis and typhoid fever. Virulence is achieved by two type III secretion systems that translocate effector proteins into host cells, where they mimic or block host protein function. Effectors translocated into host cells by the first type III secretion system facilitate invasion and stimulate intracellular signaling cascades leading to inflammation. Here, we performed global temporal analysis of host signaling events induced during the initial stages of Salmonella infection and identified the dynamics of host protein phosphorylation as well as differences between growth factor-stimulated and bacteria-induced signaling. Informatics analysis predicted that sites with altered phosphorylation in infected cells were targeted by the serine-threonine kinases Akt, protein kinase C, and Pim and that up to half of the host phosphorylation events detected after Salmonella infection required the effector protein SopB. Our data reveal extensive manipulation of host phosphorylation cascades by this Salmonella effector and provide a detailed map of the events leading to intestinal inflammation, which is the crucial host response that enables Salmonella to proliferate in the intestine.
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Affiliation(s)
- Lindsay D Rogers
- Centre for High-Throughput Biology and Department of Biochemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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49
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Watch the GAP: Emerging Roles for IQ Motif-Containing GTPase-Activating Proteins IQGAPs in Hepatocellular Carcinoma. Int J Hepatol 2012; 2012:958673. [PMID: 22973521 PMCID: PMC3438877 DOI: 10.1155/2012/958673] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/25/2012] [Accepted: 08/03/2012] [Indexed: 12/12/2022] Open
Abstract
IQ motif-containing GTPase-activating proteins IQGAP1 and IQGAP2 are highly homologous multidomain scaffolding proteins. Their major function consists of integration of Rho GTPase and Ca(2+)/calmodulin signals with cell adhesive and cytoskeletal reorganizational events. Recent studies showed that they play an important role in carcinogenesis. There is growing evidence that IQGAP2 is a novel tumor suppressor counteracting the effects of IQGAP1, an oncogene, in several cancers, especially in hepatocellular carcinoma (HCC). While HCC is highly prevalent and one of the deadliest cancers worldwide, the signaling pathways involved are not fully understood and treatment of advanced disease still represents an area of high unmet medical need. This paper compiles various findings from studies in mouse models, cell lines, and patient samples that support future development of IQGAPs into new therapeutic targets. It also discusses distinct features of IQGAP2 in an attempt to provide insight into the mechanism of the seemingly paradoxical opposing roles of the two very similar IQGAP proteins in carcinogenesis.
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50
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Chiariello CS, LaComb JF, Bahou WF, Schmidt VA. Ablation of Iqgap2 protects from diet-induced hepatic steatosis due to impaired fatty acid uptake. ACTA ACUST UNITED AC 2011; 173:36-46. [PMID: 21968151 DOI: 10.1016/j.regpep.2011.09.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 08/07/2011] [Accepted: 09/16/2011] [Indexed: 01/28/2023]
Abstract
UNLABELLED Long-chain fatty acids (LCFA) serve as structural components for membrane biogenesis and as primary energy sources during mitochondrial β-oxidation reactions. Hepatic LCFA uptake is complex, with characteristics suggestive of a dual-kinetic model manifested by rapid (carrier-assisted/facilitated) and delayed (passive diffusional) phases. Our previous work using mice deficient of the Iqgap2 gene established a highly novel link between IQGAP2, a putative GTPase-activating protein, and hepatocarcinogenesis. Now we report that Iqgap2 deficiency also results in selective loss of the facilitated phase of hepatocyte LCFA uptake with preservation of the diffusional component. This molecular defect was seen in Iqgap2(-/-) hepatocytes of all ages studied (1-, 4-, 8-months). The loss of facilitated LCFA uptake protected against development of hepatic triglyceride accumulation in Iqgap2-deficient mice fed high-fat diet, consistent with a fundamental role in physiological fat partitioning. These phenotypic changes could not be explained by genetic loss of fatty acid processing proteins known to regulate lipid uptake or metabolic processing pathways. Iqgap2-deficient livers also displayed enhanced insulin sensitivity. CONCLUSION These observations identify a novel property of the putative GTPase-activating protein IQGAP2 in LCFA uptake in vitro and in vivo, and implicate IQGAP2 in an intracellular signaling pathway necessary for functional fatty acid uptake, lipid processing, and, possibly, glucose homeostasis.
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