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Cao H, Gong H, Yu M, Pan X, Song T, Yu J, Qi Z, Du Y, Zhang R, Liu Y. The Ras GTPase-activating protein UvGap1 orchestrates conidiogenesis and pathogenesis in the rice false smut fungus Ustilaginoidea virens. Mol Plant Pathol 2024; 25:e13448. [PMID: 38502297 PMCID: PMC10950028 DOI: 10.1111/mpp.13448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 12/27/2023] [Accepted: 01/30/2024] [Indexed: 03/21/2024]
Abstract
Ras GTPase-activating proteins (Ras GAPs) act as negative regulators for Ras proteins and are involved in various signalling processes that influence cellular functions. Here, the function of four Ras GAPs, UvGap1 to UvGap4, was identified and analysed in Ustilaginoidea virens, the causal agent of rice false smut disease. Disruption of UvGAP1 or UvGAP2 resulted in reduced mycelial growth and an increased percentage of larger or dumbbell-shaped conidia. Notably, the mutant ΔUvgap1 completely lost its pathogenicity. Compared to the wild-type strain, the mutants ΔUvgap1, ΔUvgap2 and ΔUvgap3 exhibited reduced tolerance to H2 O2 oxidative stress. In particular, the ΔUvgap1 mutant was barely able to grow on the H2 O2 plate, and UvGAP1 was found to influence the expression level of genes involved in reactive oxygen species synthesis and scavenging. The intracellular cAMP level in the ΔUvgap1 mutant was elevated, as UvGap1 plays an important role in maintaining the intracellular cAMP level by affecting the expression of phosphodiesterases, which are linked to cAMP degradation in U. virens. In a yeast two-hybrid assay, UvRas1 and UvRasGef (Ras guanyl nucleotide exchange factor) physically interacted with UvGap1. UvRas2 was identified as an interacting partner of UvGap1 through a bimolecular fluorescence complementation assay and affinity capture-mass spectrometry analysis. Taken together, these findings suggest that the UvGAP1-mediated Ras pathway is essential for the development and pathogenicity of U. virens.
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Affiliation(s)
- Huijuan Cao
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Hao Gong
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Mina Yu
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Xiayan Pan
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Tianqiao Song
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Junjie Yu
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Zhongqiang Qi
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Yan Du
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Rongsheng Zhang
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
| | - Yongfeng Liu
- Institute of Plant ProtectionJiangsu Academy of Agricultural SciencesNanjingChina
- College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
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Zhang L, Wang Z, Tang F, Wu M, Pan Y, Bai S, Lu B, Zhong S, Xie Y. Identification of Senescence-Associated Biomarkers in Diabetic Glomerulopathy Using Integrated Bioinformatics Analysis. J Diabetes Res 2024; 2024:5560922. [PMID: 38292407 PMCID: PMC10827377 DOI: 10.1155/2024/5560922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 02/01/2024] Open
Abstract
Background Cellular senescence is thought to play a significant role in the onset and development of diabetic nephropathy. The goal of this study was to explore potential biomarkers associated with diabetic glomerulopathy from the perspective of senescence. Methods Datasets about human glomerular biopsy samples related to diabetic nephropathy were systematically obtained from the Gene Expression Omnibus database. Hub senescence-associated genes were investigated by differential gene analysis and Least Absolute Shrinkage and Selection Operator analysis. Cluster analysis was employed to identify senescence molecular subtypes. A single-cell dataset was used to validate the above findings and further evaluate the senescence environment. The relationship between these genes and the glomerular filtration rate was explored based on the Nephroseq database. These gene expressions have also been explored in various kidney diseases. Results Twelve representative senescence-associated genes (VEGFA, IQGAP2, JUN, PLAT, ETS2, ANG, MMP14, VEGFC, SERPINE2, CXCR2, PTGES, and EGF) were finally identified. Biological changes in immune inflammatory response, cell cycle regulation, metabolic regulation, and immune microenvironment have been observed across different molecular subtypes. The above results were also validated based on single-cell analysis. Additionally, we also identified several significantly altered cell communication pathways, including COLLAGEN, PTN, LAMININ, SPP1, and VEGF. Finally, almost all these genes could well predict the occurrence of diabetic glomerulopathy based on receiver operating characteristic analysis and are associated with the glomerular filtration rate. These genes are differently expressed in various kidney diseases. Conclusion The present study identified potential senescence-associated biomarkers and further explored the heterogeneity of diabetic glomerulopathy that might provide new insights into the diagnosis, assessment, management, and personalized treatment of DN.
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Affiliation(s)
- Li Zhang
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou 215008, Jiangsu, China
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Zhaoxiang Wang
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Fengyan Tang
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Menghuan Wu
- Department of Cardiology, Xuyi People's Hospital, Xuyi 211700, Jiangsu, China
| | - Ying Pan
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Song Bai
- Department of Cardiology, Xuyi People's Hospital, Xuyi 211700, Jiangsu, China
| | - Bing Lu
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Shao Zhong
- Department of Endocrinology, The First People's Hospital of Kunshan, Kunshan 215300, Jiangsu, China
| | - Ying Xie
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, Suzhou 215008, Jiangsu, China
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López-Moreno Y, Cabezudo-García P, Ciano-Petersen NL, García-Martín G, Serrano-Castro PJ. Epileptic and neurodevelopmental encephalopathy associated to SYNGAP1 mutation: Description of a case and treatment response to cannabidiol. Neurologia 2024; 39:101-103. [PMID: 38056595 DOI: 10.1016/j.nrleng.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 01/01/2023] [Indexed: 12/08/2023] Open
Affiliation(s)
- Y López-Moreno
- Instituto de Investigación Biomédica de Málaga - IBIMA, Málaga, Spain.
| | - P Cabezudo-García
- Instituto de Investigación Biomédica de Málaga - IBIMA, Málaga, Spain; Red Andaluza de Investigación Clínica y Traslacional en Neurología (NeuroRECA), Málaga, Spain; Servicio de Neurología, Hospital Regional Universitario de Málaga, Málaga, Spain
| | - N L Ciano-Petersen
- Instituto de Investigación Biomédica de Málaga - IBIMA, Málaga, Spain; Red Andaluza de Investigación Clínica y Traslacional en Neurología (NeuroRECA), Málaga, Spain; Servicio de Neurología, Hospital Regional Universitario de Málaga, Málaga, Spain
| | - G García-Martín
- Instituto de Investigación Biomédica de Málaga - IBIMA, Málaga, Spain; Red Andaluza de Investigación Clínica y Traslacional en Neurología (NeuroRECA), Málaga, Spain; Servicio de Neurología, Hospital Regional Universitario de Málaga, Málaga, Spain
| | - P J Serrano-Castro
- Instituto de Investigación Biomédica de Málaga - IBIMA, Málaga, Spain; Red Andaluza de Investigación Clínica y Traslacional en Neurología (NeuroRECA), Málaga, Spain; Servicio de Neurología, Hospital Regional Universitario de Málaga, Málaga, Spain
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Thomas BR, Ludwig NN, Falligant JM, Kurtz PF, Smith-Hicks C. Severe behavior problems in SYNGAP1-related disorder: A summary of 11 consecutive patients in a tertiary care specialty clinic. Epilepsy Behav 2024; 150:109584. [PMID: 38096660 DOI: 10.1016/j.yebeh.2023.109584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/24/2023] [Accepted: 12/05/2023] [Indexed: 01/14/2024]
Abstract
SYNGAP1-related disorder (SYNGAP1-RD) is a neurodevelopmental disorder that is commonly associated with epilepsy, autism spectrum disorder (ASD), and disruptive behaviors. In this study, behavior problems in 11 consecutive patients with SYNGAP1-RD are described and quantified based on a behavioral screening conducted within the context of a multi-disciplinary tertiary care specialty clinic visit. The behavioral phenotype was then compared to published samples of behavior problems in ASD and other genetic cause of epilepsy occurring in the context of neurodevelopmental disorders using results from the Aberrant Behavior Checklist-Community (ABC-C), an empirically derived outcome measure. We report common antecedent and consequent events surrounding problem behavior across individuals. Additionally, we report on the management approach of caregivers and the impact of problem behaviors on the family. Our results suggest a number of commonalities between behavioral profiles in SYNGAP1-RD with ASD and other genetic causes of developmental and epileptic encephalopathies, and also highlight severe behavior problems as a specific behavioral phenotype of SYNGAP1-RD.
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Affiliation(s)
- Benjamin R Thomas
- Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA.
| | - Natasha N Ludwig
- Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA; Johns Hopkins University School of Medicine, USA
| | - John Michael Falligant
- Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA; Johns Hopkins University School of Medicine, USA
| | - Patricia F Kurtz
- Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA; Johns Hopkins University School of Medicine, USA
| | - Constance Smith-Hicks
- Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA; Johns Hopkins University School of Medicine, USA
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Tourrière H, Chebli K, Zekri L, Courselaud B, Blanchard JM, Bertrand E, Tazi J. The RasGAP-associated endoribonuclease G3BP mediates stress granule assembly. J Cell Biol 2023; 222:e200212128072023new. [PMID: 37672657 PMCID: PMC10482220 DOI: 10.1083/jcb.200212128072023new] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 07/24/2023] [Indexed: 09/08/2023] Open
Abstract
Stress granules (SGs) are formed in the cytoplasm in response to various toxic agents and are believed to play a critical role in the regulation of mRNA metabolism during stress. In SGs, mRNAs are stored in an abortive translation initiation complex that can be routed to either translation initiation or degradation. Here, we show that G3BP, a phosphorylation-dependent endoribonuclease that interacts with RasGAP, is recruited to SGs in cells exposed to arsenite. G3BP may thus determine the fate of mRNAs during cellular stress. Remarkably, SG assembly can be either dominantly induced by G3BP overexpression, or on the contrary, inhibited by expressing a central domain of G3BP. This region binds RasGAP and contains serine 149 whose dephosphorylation is induced by arsenite treatment. Critically, a non-phosphorylatable G3BP mutant (S149A) oligomerizes and assembles SG. These results suggest that G3BP is an effector of SG assembly and that Ras signaling contributes to this process by regulating G3BP dephosphorylation.
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Affiliation(s)
- Hélène Tourrière
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Karim Chebli
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Latifa Zekri
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Brice Courselaud
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Jean Marie Blanchard
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
| | - Jamal Tazi
- Institut de Génétique Moléculaire de Montpellier, UMR 5535 du Centre National de la Recherche Scientifique (CNRS), Université Montpellier, Montpellier, France
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Johansen KH, Golec DP, Okkenhaug K, Schwartzberg PL. Mind the GAP: RASA2 and RASA3 GTPase-activating proteins as gatekeepers of T cell activation and adhesion. Trends Immunol 2023; 44:917-931. [PMID: 37858490 PMCID: PMC10621891 DOI: 10.1016/j.it.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 09/11/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023]
Abstract
Following stimulation, the T cell receptor (TCR) and its coreceptors integrate multiple intracellular signals to initiate T cell proliferation, migration, gene expression, and metabolism. Among these signaling molecules are the small GTPases RAS and RAP1, which induce MAPK pathways and cellular adhesion to activate downstream effector functions. Although many studies have helped to elucidate the signaling intermediates that mediate T cell activation, the molecules and pathways that keep naive T cells in check are less understood. Several recent studies provide evidence that RASA2 and RASA3, which are GAP1-family GTPase-activating proteins (GAPs) that inactivate RAS and RAP1, respectively, are crucial molecules that limit T cell activation and adhesion. In this review we describe recent data on the roles of RASA2 and RASA3 as gatekeepers of T cell activation and migration.
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Affiliation(s)
- Kristoffer H Johansen
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK; Section of Experimental and Translational Immunology, Department of Health Technology, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| | - Dominic P Golec
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Klaus Okkenhaug
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Pamela L Schwartzberg
- Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Araki Y, Gerber EE, Rajkovich KE, Hong I, Johnson RC, Lee HK, Kirkwood A, Huganir RL. Mouse models of SYNGAP1-related intellectual disability. Proc Natl Acad Sci U S A 2023; 120:e2308891120. [PMID: 37669379 PMCID: PMC10500186 DOI: 10.1073/pnas.2308891120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 07/28/2023] [Indexed: 09/07/2023] Open
Abstract
SYNGAP1 is a Ras-GTPase-activating protein highly enriched at excitatory synapses in the brain. De novo loss-of-function mutations in SYNGAP1 are a major cause of genetically defined neurodevelopmental disorders (NDDs). These mutations are highly penetrant and cause SYNGAP1-related intellectual disability (SRID), an NDD characterized by cognitive impairment, social deficits, early-onset seizures, and sleep disturbances. Studies in rodent neurons have shown that Syngap1 regulates developing excitatory synapse structure and function, and heterozygous Syngap1 knockout mice have deficits in synaptic plasticity, learning, and memory and have seizures. However, how specific SYNGAP1 mutations found in humans lead to disease has not been investigated in vivo. To explore this, we utilized the CRISPR-Cas9 system to generate knock-in mouse models with two distinct known causal variants of SRID: one with a frameshift mutation leading to a premature stop codon, SYNGAP1; L813RfsX22, and a second with a single-nucleotide mutation in an intron that creates a cryptic splice acceptor site leading to premature stop codon, SYNGAP1; c.3583-9G>A. While reduction in Syngap1 mRNA varies from 30 to 50% depending on the specific mutation, both models show ~50% reduction in Syngap1 protein, have deficits in synaptic plasticity, and recapitulate key features of SRID including hyperactivity and impaired working memory. These data suggest that half the amount of SYNGAP1 protein is key to the pathogenesis of SRID. These results provide a resource to study SRID and establish a framework for the development of therapeutic strategies for this disorder.
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Affiliation(s)
- Yoichi Araki
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Elizabeth E. Gerber
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Kacey E. Rajkovich
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Ingie Hong
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Richard C. Johnson
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Hey-Kyoung Lee
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Alfredo Kirkwood
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Richard L. Huganir
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD21205
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Li J, Guo Q, Xing R. Construction and validation of an immune infiltration-related risk model for predicting prognosis and immunotherapy response in low grade glioma. BMC Cancer 2023; 23:727. [PMID: 37543576 PMCID: PMC10403952 DOI: 10.1186/s12885-023-11222-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 07/25/2023] [Indexed: 08/07/2023] Open
Abstract
BACKGROUND Low grade glioma (LGG) is considered a heterogeneous tumor with highly variable survival and limited efficacy of immunotherapy. To identify high-risk subsets and apply immunotherapy effectively in LGG, the status and function of immune infiltration in the glioma microenvironment must be explored. METHODS Four independent glioma cohorts comprising 1,853 patients were enrolled for bioinformatics analysis. We used ConsensusClusterPlus to cluster patients into four different immune subtypes based on immune infiltration. The immune-infiltration signature (IIS) was constructed by LASSO regression analysis. Somatic mutation and copy number variation (CNV) analyses were performed to explore genomic and transcriptomic traits in the high- and low- risk groups. The correlation between response to programmed cell death 1 (PD-1) blockade and the IIS risk score was confirmed in an in vivo glioma model. RESULTS Patients were clustered into four different immune subtypes based on immune infiltration, and the high immune infiltration subtype was associated with worse survival in LGG. The high immune infiltration subtype had stronger inflammatory response, immune response and immune cell chemotaxis. The IIS, consisting of EMP3, IQGAP2, METTL7B, SLC1A6 and TNFRSF11B, could predict LGG malignant progression, which was validated with internal clinical samples. M2 macrophage infiltration positively correlated with the IIS risk score. The high-risk group had significantly more somatic mutations and CNVs. The IIS risk score was related to immunomodulatory molecules and could predict immunotherapy clinical benefit. In vivo, immunotherapy-sensitive glioma model exhibited higher IIS risk score and more infiltration of immune cells, especially M2 macrophages. The IIS risk score was decreased in an immunotherapy-sensitive glioma model after anti-PD1 immunotherapy. CONCLUSION Different immune subtypes of LGG had unique immune cell infiltration characteristics, and the high immune infiltration subtype was associated with immunosuppressive signaling pathways. A novel IIS prognostic model based on immune infiltration status was constructed for immunophenotypic classification, risk stratification, prognostication and immunotherapy response prediction in LGG.
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Affiliation(s)
- Jinna Li
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110000, China
| | - Qing Guo
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, 110000, China.
| | - Rui Xing
- Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, 110000, China.
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Wang W, Yao J, Li W, Wu Y, Duan H, Xu C, Tian X, Li S, Tan Q, Zhang D. Epigenome-wide association study in Chinese monozygotic twins identifies DNA methylation loci associated with blood pressure. Clin Epigenetics 2023; 15:38. [PMID: 36869404 PMCID: PMC9985232 DOI: 10.1186/s13148-023-01457-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Hypertension is a crucial risk factor for developing cardiovascular disease and reducing life expectancy. We aimed to detect DNA methylation (DNAm) variants potentially related to systolic blood pressure (SBP) and diastolic blood pressure (DBP) by conducting epigenome-wide association studies in 60 and 59 Chinese monozygotic twin pairs, respectively. METHODS Genome-wide DNA methylation profiling in whole blood of twins was performed using Reduced Representation Bisulfite Sequencing, yielding 551,447 raw CpGs. Association between DNAm of single CpG and blood pressure was tested by applying generalized estimation equation. Differentially methylated regions (DMRs) were identified by comb-P approach. Inference about Causation through Examination of Familial Confounding was utilized to perform the causal inference. Ontology enrichment analysis was performed using Genomic Regions Enrichment of Annotations Tool. Candidate CpGs were quantified using Sequenom MassARRAY platform in a community population. Weighted gene co-expression network analysis (WGCNA) was conducted using gene expression data. RESULTS The median age of twins was 52 years (95% range 40, 66). For SBP, 31 top CpGs (p < 1 × 10-4) and 8 DMRs were identified, with several DMRs within NFATC1, CADM2, IRX1, COL5A1, and LRAT. For DBP, 43 top CpGs (p < 1 × 10-4) and 12 DMRs were identified, with several DMRs within WNT3A, CNOT10, and DAB2IP. Important pathways, such as Notch signaling pathway, p53 pathway by glucose deprivation, and Wnt signaling pathway, were significantly enriched for SBP and DBP. Causal inference analysis suggested that DNAm at top CpGs within NDE1, MYH11, SRRM1P2, and SMPD4 influenced SBP, while SBP influenced DNAm at CpGs within TNK2. DNAm at top CpGs within WNT3A influenced DBP, while DBP influenced DNAm at CpGs within GNA14. Three CpGs mapped to WNT3A and one CpG mapped to COL5A1 were validated in a community population, with a hypermethylated and hypomethylated direction in hypertension cases, respectively. Gene expression analysis by WGCNA further identified some common genes and enrichment terms. CONCLUSION We detect many DNAm variants that may be associated with blood pressure in whole blood, particularly the loci within WNT3A and COL5A1. Our findings provide new clues to the epigenetic modification underlying hypertension pathogenesis.
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Affiliation(s)
- Weijing Wang
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
| | - Jie Yao
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
- Jiangsu Health Development Research Center, Nanjing, Jiangsu, China
| | - Weilong Li
- Population Research Unit, Faculty of Social Sciences, University of Helsinki, Helsinki, Finland
| | - Yili Wu
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
| | - Haiping Duan
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Chunsheng Xu
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Xiaocao Tian
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Shuxia Li
- Unit of Human Genetics, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Qihua Tan
- Unit of Human Genetics, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Dongfeng Zhang
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China.
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Lin Z, Tang X, Cao Y, Yang L, Jiang M, Li X, Min J, Chen B, Yang Y, Gu C. CD229 interacts with RASAL3 to activate RAS/ERK pathway in multiple myeloma proliferation. Aging (Albany NY) 2022; 14:9264-9279. [PMID: 36445333 PMCID: PMC9740379 DOI: 10.18632/aging.204405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 11/16/2022] [Indexed: 11/30/2022]
Abstract
Multiple myeloma (MM) is an incurable plasma cell malignancy, while CAR-T therapy offers a new direction for the treatment of MM. Recently, signaling lymphocytic activation molecule family 3 (CD229), a cell surface immune receptor belonging to the signaling lymphocyte activating molecule family (SLAMF), is emerging as a CAR-T therapeutic target in MM. However, a clear role of CD229 in MM remains elusive. In this study, MM patients with elevated CD229 expression achieved poor prognosis by analyzing MM clinical databases. In addition, CD229 promoted MM cell proliferation in vitro as well as in xenograft mouse model in vivo. Mechanism study revealed that CD229 promoted MM cell proliferation by regulating the RAS/ERK signaling pathway. Further exploration employed co-immunoprecipitation coupled with mass spectrometry to identify RASAL3 as an important downstream protein of CD229. Additionally, we developed a co-culture method combined with the immunofluorescence assay to confirm that intercellular tyrosine phosphorylation mediated self-activation of CD229 to activate RAS/ERK signaling pathway via interacting with RASAL3. Taken together, these findings not only demonstrate the oncogenic role of CD229 in MM cell proliferation, but also illustrate the potential of CD229 as a promising therapeutic target for MM treatment.
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Affiliation(s)
- Zigen Lin
- Department of Hematology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xiaozhu Tang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yuhao Cao
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Lijin Yang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Mingmei Jiang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xinying Li
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jie Min
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Bing Chen
- Department of Hematology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Ye Yang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chunyan Gu
- Department of Hematology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
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11
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Zhang W, Zhou H, Jiang Y, He J, Yao Y, Wang J, Liu X, Leptihn S, Hua X, Yu Y. Acinetobacter baumannii Outer Membrane Protein A Induces Pulmonary Epithelial Barrier Dysfunction and Bacterial Translocation Through The TLR2/IQGAP1 Axis. Front Immunol 2022; 13:927955. [PMID: 35844614 PMCID: PMC9280087 DOI: 10.3389/fimmu.2022.927955] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/02/2022] [Indexed: 01/15/2023] Open
Abstract
Pulmonary epithelial barrier dysfunction is a critical pathophysiological process in pneumonia and associated invasive infections, such as those caused by Acinetobacter baumannii. However, the mechanisms underlying A. baumannii-induced pulmonary epithelial barrier dysfunction and bacterial translocation remain unclear. In this study, lungs of mice and A549 human epithelial cell monolayers were challenged with the A. baumannii wild-type strain and an outer membrane protein A (ompA) deletion strain. In addition, epithelial cells in culture were treated with purified OmpA protein or transfected with a eukaryotic expression vector encoding ompA (pCMV-ompA). Bacterial translocation across cell monolayers and intrapulmonary burden were measured, barrier function was evaluated in vivo and in vitro; cell migration ability was determined. The specific inhibitors C29 and JSH-23 were used to suppress the activity of Toll-like receptor 2 (TLR2) and of NF-κB, respectively. IQ-GTPase-activating protein 1 (IQGAP1) small interfering RNA was used to knock down endogenous IQGAP1 expression. In this work, we show that OmpA from A. baumannii increased the production of pro-inflammatory cytokines, remodeled the cytoskeleton, and internalized intercellular adherens junctions (AJs); these changes eventually induced pulmonary epithelial barrier dysfunction to promote bacterial translocation. IQGAP1-targeting small interfering RNA and chemical inhibition of TLR2 or NF-κB prevented high permeability of the pulmonary epithelial barrier. TLR2/NF-κB signaling was involved in OmpA-induced inflammation, IQGAP1-mediated OmpA-induced opening of the pulmonary epithelial barrier via cytoskeleton dynamic remodeling, and cellular redistribution of the major AJ protein, E-cadherin. These observations indicate that A. baumannii uses OmpA to overcome epithelial defences and cross the pulmonary epithelial barrier.
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Affiliation(s)
- Wang Zhang
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Hua Zhou
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yan Jiang
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Jintao He
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Yue Yao
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Jianfeng Wang
- Department of Respiratory and Critical Care Medicine, Zhejiang Provincial Hospital of Chinese Medicine, Hangzhou, China
| | - Xiaochen Liu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
| | - Sebastian Leptihn
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Zhejiang University-University of Edinburgh Institute, Zhejiang University, Haining, China
- University of Edinburgh Medical School, Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Xiaoting Hua
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
- *Correspondence: Yunsong Yu, ; Xiaoting Hua,
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
- *Correspondence: Yunsong Yu, ; Xiaoting Hua,
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Hidalgo F, Nocka LM, Shah NH, Gorday K, Latorraca NR, Bandaru P, Templeton S, Lee D, Karandur D, Pelton JG, Marqusee S, Wemmer D, Kuriyan J. A saturation-mutagenesis analysis of the interplay between stability and activation in Ras. eLife 2022; 11:e76595. [PMID: 35272765 PMCID: PMC8916776 DOI: 10.7554/elife.76595] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/25/2022] [Indexed: 12/31/2022] Open
Abstract
Cancer mutations in Ras occur predominantly at three hotspots: Gly 12, Gly 13, and Gln 61. Previously, we reported that deep mutagenesis of H-Ras using a bacterial assay identified many other activating mutations (Bandaru et al., 2017). We now show that the results of saturation mutagenesis of H-Ras in mammalian Ba/F3 cells correlate well with the results of bacterial experiments in which H-Ras or K-Ras are co-expressed with a GTPase-activating protein (GAP). The prominent cancer hotspots are not dominant in the Ba/F3 data. We used the bacterial system to mutagenize Ras constructs of different stabilities and discovered a feature that distinguishes the cancer hotspots. While mutations at the cancer hotspots activate Ras regardless of construct stability, mutations at lower-frequency sites (e.g. at Val 14 or Asp 119) can be activating or deleterious, depending on the stability of the Ras construct. We characterized the dynamics of three non-hotspot activating Ras mutants by using NMR to monitor hydrogen-deuterium exchange (HDX). These mutations result in global increases in HDX rates, consistent with destabilization of Ras. An explanation for these observations is that mutations that destabilize Ras increase nucleotide dissociation rates, enabling activation by spontaneous nucleotide exchange. A further stability decrease can lead to insufficient levels of folded Ras - and subsequent loss of function. In contrast, the cancer hotspot mutations are mechanism-based activators of Ras that interfere directly with the action of GAPs. Our results demonstrate the importance of GAP surveillance and protein stability in determining the sensitivity of Ras to mutational activation.
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Affiliation(s)
- Frank Hidalgo
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
| | - Laura M Nocka
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
| | - Neel H Shah
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, Columbia UniversityNew YorkUnited States
| | - Kent Gorday
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Biophysics Graduate Group, University of California, BerkeleyBerkeleyUnited States
| | - Naomi R Latorraca
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Pradeep Bandaru
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Sage Templeton
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - David Lee
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Deepti Karandur
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Jeffrey G Pelton
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
| | - Susan Marqusee
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - David Wemmer
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
| | - John Kuriyan
- California Institute for Quantitative Biosciences (QB3), University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California, BerkeleyBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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Stanic B, Samardzija Nenadov D, Fa S, Pogrmic-Majkic K, Andric N. Integration of data from the cell-based ERK1/2 ELISA and the Comparative Toxicogenomics Database deciphers the potential mode of action of bisphenol A and benzo[a]pyrene in lung neoplasm. Chemosphere 2021; 285:131527. [PMID: 34329126 DOI: 10.1016/j.chemosphere.2021.131527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/22/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
Chemicals can activate a variety of signaling pathways, initiating changes in gene expression and cellular functions. Here, we combined experimental data on the chemical-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation with the Comparative Toxicogenomics Database (CTD) to connect signaling, genes, and phenotypes to reveal the potential chemical's mode of action (MOA) responsible for the disease state. Experimental data on ERK1/2 activation were derived from the cell-based phospho-ERK1/2 ELISA on human alveolar epithelial cells A549. A549 cells were exposed to bisphenol A (BPA), benzo[a]pyrene (BaP), tributyltin (TBT), and ibuprofen from 10-12 M to 10-5 M. Results show that BPA, BaP, and TBT can activate ERK1/2 in A549 cells. We selected BPA and BaP to elucidate the molecular events connecting chemical exposure, ERK1/2 signaling, phenotypes, and lung neoplasm (LN) using CTD. CTD analysis showed that BPA and BaP share 26 mitogen-activated protein kinase 1/3 (MAPK1/3) signaling genes associated with LN. Phenotype prioritization revealed 37 BPA, 10 BaP, and 11 shared key phenotypes associated with LN. Alignment of MAPK1/3 signaling genes and phenotypes showed that ERK1/2 and oxidative stress, EGFR gene, and positive regulation of cell proliferation and migration could be the shared key events (KE) for BPA and BaP. This analysis also identified protein kinase B and ERK1/2 signaling, FGF9, FGFR1 and FGFR2 genes, positive regulation of cell proliferation and angiogenesis as KE in MOA for BPA, whereas ERK1/2 signaling, IL6 and DAB2IP genes, negative regulation of cell proliferation and inflammatory response were identified as KE in MOA for BaP.
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Affiliation(s)
- Bojana Stanic
- University of Novi Sad, Faculty of Sciences, Department of Biology and Ecology, Serbia
| | | | - Svetlana Fa
- University of Novi Sad, Faculty of Sciences, Department of Biology and Ecology, Serbia
| | | | - Nebojsa Andric
- University of Novi Sad, Faculty of Sciences, Department of Biology and Ecology, Serbia.
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Malone ET, Ganther S, Mena N, Radaic A, Shariati K, Kindberg A, Tafolla C, Kamarajan P, Fenno JC, Zhan L, Kapila YL. Treponema denticola-Induced RASA4 Upregulation Mediates Cytoskeletal Dysfunction and MMP-2 Activity in Periodontal Fibroblasts. Front Cell Infect Microbiol 2021; 11:671968. [PMID: 34094999 PMCID: PMC8171266 DOI: 10.3389/fcimb.2021.671968] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/26/2021] [Indexed: 12/16/2022] Open
Abstract
The periodontal complex consists of the periodontal ligament (PDL), alveolar bone, and cementum, which work together to turn mechanical load into biological responses that are responsible for maintaining a homeostatic environment. However oral microbes, under conditions of dysbiosis, may challenge the actin dynamic properties of the PDL in the context of periodontal disease. To study this process, we examined host-microbial interactions in the context of the periodontium via molecular and functional cell assays and showed that human PDL cell interactions with Treponema denticola induce actin depolymerization through a novel actin reorganization signaling mechanism. This actin reorganization mechanism and loss of cell adhesion is a pathological response characterized by an initial upregulation of RASA4 mRNA expression resulting in an increase in matrix metalloproteinase-2 activity. This mechanism is specific to the T. denticola effector protein, dentilisin, thereby uncovering a novel effect for Treponema denticola-mediated RASA4 transcriptional activation and actin depolymerization in primary human PDL cells.
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Affiliation(s)
- Erin Trent Malone
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Sean Ganther
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Nevina Mena
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Allan Radaic
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Keemia Shariati
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Abigail Kindberg
- Bush Laboratory, Department of Cell and Tissue Biology, Biomedical Sciences Graduate, University of California San Francisco, San Francisco, CA, United States
| | - Christian Tafolla
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Pachiyappan Kamarajan
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - J. Christopher Fenno
- Fenno Laboratory, Department of Biological and Material Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
| | - Ling Zhan
- Zhan Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
| | - Yvonne L. Kapila
- Kapila Laboratory, Department of Orofacial Sciences, School of Dentistry San Francisco, University of California San Francisco, San Francisco, CA, United States
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15
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Panas MD, Kedersha N, Schulte T, Branca RM, Ivanov P, Anderson P. Phosphorylation of G3BP1-S149 does not influence stress granule assembly. J Cell Biol 2019; 218:2425-2432. [PMID: 31171631 PMCID: PMC6605800 DOI: 10.1083/jcb.201801214] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/06/2019] [Accepted: 05/14/2019] [Indexed: 12/17/2022] Open
Abstract
Tourrière et al. (2013. J. Cell Biol. https://doi.org/10.1083/jcb.200212128) reported that G3BP1-S149 dephosphorylation promotes stress granule formation. We show that constructs used to establish this conclusion contain additional mutations causing these phenotypes, and that S149 phosphorylation status does not change upon stress.
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Affiliation(s)
- Marc D Panas
- Division of Rheumatology, Immunology and Allergy, Harvard Medical School and Brigham and Women's Hospital, Boston, MA
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Nancy Kedersha
- Division of Rheumatology, Immunology and Allergy, Harvard Medical School and Brigham and Women's Hospital, Boston, MA
| | - Tim Schulte
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Rui M Branca
- Clinical Proteomics Mass Spectrometry, Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Pavel Ivanov
- Division of Rheumatology, Immunology and Allergy, Harvard Medical School and Brigham and Women's Hospital, Boston, MA
| | - Paul Anderson
- Division of Rheumatology, Immunology and Allergy, Harvard Medical School and Brigham and Women's Hospital, Boston, MA
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16
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Hamdan FF, Gauthier J, Spiegelman D, Noreau A, Yang Y, Pellerin S, Dobrzeniecka S, Côté M, Perreau-Linck E, Carmant L, D'Anjou G, Fombonne E, Addington AM, Rapoport JL, Delisi LE, Krebs MO, Mouaffak F, Joober R, Mottron L, Drapeau P, Marineau C, Lafrenière RG, Lacaille JC, Rouleau GA, Michaud JL. Mutations in SYNGAP1 in autosomal nonsyndromic mental retardation. N Engl J Med 2009; 360:599-605. [PMID: 19196676 PMCID: PMC2925262 DOI: 10.1056/nejmoa0805392] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Although autosomal forms of nonsyndromic mental retardation account for the majority of cases of mental retardation, the genes that are involved remain largely unknown. We sequenced the autosomal gene SYNGAP1, which encodes a ras GTPase-activating protein that is critical for cognition and synapse function, in 94 patients with nonsyndromic mental retardation. We identified de novo truncating mutations (K138X, R579X, and L813RfsX22) in three of these patients. In contrast, we observed no de novo or truncating mutations in SYNGAP1 in samples from 142 subjects with autism spectrum disorders, 143 subjects with schizophrenia, and 190 control subjects. These results indicate that SYNGAP1 disruption is a cause of autosomal dominant nonsyndromic mental retardation.
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Affiliation(s)
- Fadi F Hamdan
- Centre Hospitalier Universitaire Sainte-Justine Research Center, Centre of Excellence in Neuromics, Université de Montréal, QC, Canada
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19
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Abstract
Preimplantation development encompasses the interval from insemination until embryo implantation and thus includes the 'freeliving' period of oviduct and uterine development. Formation of the blastocyst is required for implantation and establishment of pregnancy, and is a principal determinant of embryo quality prior to embryo transfer. Development through this period is regulated by the expression of specific gene families that encode for cell polarity, cell junctional, cytoskeletal, ion transporter, and water channel gene products that direct the acquisition of cell polarity and differentiation of the outer cells of the early embryo. This results in the formation of the trophectoderm, which is the first epithelium of development. This review considers the roles of each of these gene families in trophectoderm differentiation and blastocyst formation. The principal hypothesis under investigation is that blastocyst formation is regulated by a Na/K-ATPase-generated trans-trophectoderm ion gradient that promotes the accumulation of water across the epithelium. This, combined with the formation of the tight junction seal controlling paracellular movement of water between adjacent trophectoderm cells, results in the formation of a fluid-filled blastocyst cavity and the expansion of the blastocyst. Results from recent experiments, however, have cast some doubt on the role of Na/K-ATPase in mediating these events and have defined water channels or Aquaporins (AQPs) as physiological mediators of fluid movement across the trophectoderm. In addition, studies have now implicated mitogen-activated protein kinase (MAPK) signaling as an important mediator of development to the blastocyst stage. Such studies define the physiology of blastocyst formation and serve to support the application of assisted reproductive technologies (ART) to both human and animal species.
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Affiliation(s)
- A J Watson
- Department of Biochemistry and Molecular Biology, The University of Calgary, Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
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Izumi G, Sakisaka T, Baba T, Tanaka S, Morimoto K, Takai Y. Endocytosis of E-cadherin regulated by Rac and Cdc42 small G proteins through IQGAP1 and actin filaments. ACTA ACUST UNITED AC 2004; 166:237-48. [PMID: 15263019 PMCID: PMC2172308 DOI: 10.1083/jcb.200401078] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
E-cadherin is a key cell–cell adhesion molecule at adherens junctions (AJs) and undergoes endocytosis when AJs are disrupted by the action of extracellular signals. To elucidate the mechanism of this endocytosis, we developed here a new cell-free assay system for this reaction using the AJ-enriched fraction from rat liver. We found here that non-trans-interacting, but not trans-interacting, E-cadherin underwent endocytosis in a clathrin-dependent manner. The endocytosis of trans-interacting E-cadherin was inhibited by Rac and Cdc42 small G proteins, which were activated by trans-interacting E-cadherin or trans-interacting nectins, which are known to induce the formation of AJs in cooperation with E-cadherin. This inhibition was mediated by reorganization of the actin cytoskeleton by Rac and Cdc42 through IQGAP1, an actin filament-binding protein and a downstream target of Rac and Cdc42. These results indicate the important role of the Rac/Cdc42-IQGAP1 system in the dynamic organization and maintenance of the E-cadherin–based AJs.
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Affiliation(s)
- Genkichi Izumi
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, Osaka 565-0871, Japan
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Abstract
During cytokinesis, furrow ingression and plasma membrane fission irreversibly separate daughter cells. How actomyosin ring assembly and contraction, vesicle fusion, and abscission are spatially coordinated was unknown. We found that during cytokinesis septin rings, located on both sides of the actomyosin ring, acted as barriers to compartmentalize the cortex around the cleavage site. Compartmentalization maintained diffusible cortical factors, such as the exocyst and the polarizome, to the site of cleavage. In turn, such factors were required for actomyosin ring function and membrane abscission. Thus, a specialized cortical compartment ensures the spatial coordination of cytokinetic events.
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Affiliation(s)
- Jeroen Dobbelaere
- Institute of Biochemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, 8093 Zürich, Switzerland
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Krapivinsky G, Medina I, Krapivinsky L, Gapon S, Clapham DE. SynGAP-MUPP1-CaMKII Synaptic Complexes Regulate p38 MAP Kinase Activity and NMDA Receptor- Dependent Synaptic AMPA Receptor Potentiation. Neuron 2004; 43:563-74. [PMID: 15312654 DOI: 10.1016/j.neuron.2004.08.003] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 06/01/2004] [Accepted: 07/28/2004] [Indexed: 01/07/2023]
Abstract
The synapse contains densely localized and interacting proteins that enable it to adapt to changing inputs. We describe a Ca2+-sensitive protein complex involved in the regulation of AMPA receptor synaptic plasticity. The complex is comprised of MUPPI, a multi-PDZ domain-containing protein; SynGAP, a synaptic GTPase-activating protein; and the Ca2+/calmodulin-dependent kinase CaMKII. In synapses of hippocampal neurons, SynGAP and CaMKII are brought together by direct physical interaction with the PDZ domains of MUPP1, and in this complex, SynGAP is phosphorylated. Ca2+CaM binding to CaMKII dissociates it from the MUPP1 complex, and Ca2+ entering via the NMDAR drives the dephosphorylation of SynGAP. Specific peptide-induced SynGAP dissociation from the MUPP1-CaMKII complex results in SynGAP dephosphorylation accompanied by P38 MAPK inactivation, potentiation of synaptic AMPA responses, and an increase in the number of AMPAR-containing clusters in hippocampal neuron synapses. siRNA-mediated SynGAP knockdown confirmed these results. These data implicate SynGAP in NMDAR- and CaMKII-dependent regulation of AMPAR trafficking.
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Affiliation(s)
- Grigory Krapivinsky
- Howard Hughes Medical Institute, Children's Hospital, 1309 Enders Building, 320 Longwood Avenue, Boston, Massachusetts 02115, USA
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Abstract
We isolated a gene homologous to human cdc42 (ucdc42) from a sea urchin cDNA library. The GTPgammaS-bound UCdc42 induced actin assembly in sea urchin egg extract. Proteins that are involved in this actin assembly system were searched using UCdc42-bound agarose beads. A 180-kDa protein (p180), which showed a homology to human IQGAPs, bound to the GTPgammaS-UCdc42 beads. Immunodepletion of p180 from the sea urchin egg extract abolished this actin assembly on the UCdc42 beads. Immunofluorescent localization of p180 was similar to that of the actin cytoskeleton in the egg cortex and it was concentrated in the cleavage furrow during cytokinesis. A possible role of p180 in actin assembly is discussed.
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Affiliation(s)
- Yukako Nishimura
- Division of Biology, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo
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Yan LJ, Yoshinaga N, Niida N, Okamoto Y. Isolation and characterization of 190K protein from aorta smooth muscle. Adv Exp Med Biol 2004; 538:215-20; discussion 220. [PMID: 15098669 DOI: 10.1007/978-1-4419-9029-7_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Molecular assemblies of actin and myosin for the contractility of smooth muscle are quite different from those of striated muscle. Another striking difference is that vascular smooth muscle has a potential to transform to migratory synthetic cell type. At this point of view, smooth muscle cell has properties similar to those of non-muscle. In fact, myosin Ic, a single headed unconventional myosin, was identified in aorta smooth muscle. During the studies on myosin Ic, we have found another calmodulin related 190kDa protein. This protein binds to calmodulin irrespective on calcium ion and to F-actin in an ATP independent manner. Furthermore, the F-actin binding stoichiometry diminished to half upon the addition of exogenous calmodulin. Partial amino acid sequence indicated a high homology to those of GRD (GTPase Related Domain) of human brain IQGAP1. Western blot analysis using anti-human IQGAP1 antibody also indicated a strong cross-reactivity with the protein. We have tested the protein with respect to the characteristic F-actin gelation by IQGAP1. In the presence of cdc42 and GTPgammaS, 190kDa protein could cause a high viscosity of F-actin. These data indicate a close similarity to human brain IQGAP1. The presence of IQGAP1 in aorta smooth muscle suggests contributions for cellular processes such as actin reorganization during contraction-relaxation cycle, association of cytoskeletal structure to cell membrane, organelle movement.
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Affiliation(s)
- Li-Juan Yan
- Muroran Institute of Technology, Department of Applied Chemistry, Muroran, Hokkaido 050-8585, Japan
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25
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Abstract
IQGAP1 regulates cytoskeletal dynamics through interactions with the Rho family GTPases Rac1 and Cdc42, F-actin, and beta-catenin. Calmodulin interaction with IQ motifs of IQGAP1 negatively influences these IQGAP1 interactions. Although, calmodulin interacts with IQGAP1 in the absence of Ca(2+) and was suggested to exhibit reduced binding when Ca(2+) bound, recent reports show substantially greater binding when Ca(2+) is present. Binding evaluations have primarily relied on IQGAP1 interaction with calmodulin conjugated to Sepharose 4B. In this study we evaluated the Ca(2+)-dependence of calmodulin interaction with native IQGAP1 using a series of independent biochemical approaches. We found the apparent binding of calmodulin to IQGAP1 was Ca(2+)-independent, being between 5- and 20-fold greater in the absence than in the presence of Ca(2+). In addition, calmodulin interaction with IQGAP1 was negatively regulated by buffer [Ca(2+)] (IC(50)=3.4x10(-7)M). Regulation was specific to Ca(2+), as Ba(2+) was approximately 400-fold less effective than Ca(2+) at modulating the interaction. Moreover, testing of calmodulin mutants demonstrated that apocalmodulin tightly binds IQGAP1 and that the N- and C-terminal pair of EF hands are important for Ca(2+) sensitivity. These data indicate that calmodulin may disassemble from IQGAP1 to facilitate IQGAP1 interaction with effectors of cytoskeletal reorganization during conditions of cell activation that promote increased cytosolic [Ca(2+)].
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Affiliation(s)
- Quanwen Li
- Department of Molecular and Integrative Physiology, 7807 Medical Sciences II Bldg., The University of Michigan, Ann Arbor, MI 48109-0622, USA
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26
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Abstract
Circulating blood platelets regulate the initial phase of the hemostatic response through adhesive and aggregatory events and by providing the necessary procoagulant surface for prothrombinase complex assembly and thrombin generation. The signaling pathway(s) that regulate platelet procoagulant activity are largely unknown, although they are distinct from platelet aggregatory signals linked to fibrinogen ligation to the conformationally active alpha(IIB)beta(3) integrin. We describe a novel intracellular signaling mechanism involving platelet IQGAP1 that specifically regulates the development of platelet procoagulant activity under conditions of mechanical shear stress. Murine platelets that are deficient in IQGAP1 demonstrate increased prothrombinase activity compared with wild-type littermate controls when activated by a physiological shear stress of 16 dynes/cm(2) (shear rates of 1600 s(-1)) (p < 0.0001), corresponding to approximately 2.5 times the normal shear stress, or approximately 40% degree of stenosis in coronary arteries. The exaggerated prothrombinase activity is not associated with enhanced platelet microvesiculation (cytoskeletal proteolysis) and occurs independently of the intracellular calcium release, [Ca(2+)](i), but it is specifically coupled to the alpha-granule exocytic pathway without concomitant effects on aminophospholipid exposure. These observations identify platelet IQGAP1 as an important modulator of normal hemostasis and as an appropriate pharmacological target for control of platelet procoagulant function.
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Affiliation(s)
- Wadie F Bahou
- Department of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8151, USA. wbahou@ notes.cc.sunysb.edu
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27
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Abstract
IQGAP1 binds several proteins including actin, calmodulin, E-cadherin, beta-catenin, Cdc42, Rac1, and CLIP-170. The interaction with these targets enables IQGAP1 to participate in many cellular functions varying from regulation of the cytoskeleton to gene transcription. Here we show that extracellular signal-regulated kinase (ERK) 2 binds to IQGAP1. In vitro analysis with purified proteins demonstrated a direct interaction between ERK2 and IQGAP1. Moreover, binding occurred in cells as endogenous ERK2 co-immunoprecipitated with IQGAP1 from human breast epithelial cell lysates. The association between ERK2 and IQGAP1 was independent of epidermal growth factor. The in vivo interaction has functional significance. Manipulation of intracellular IQGAP1 levels significantly reduced growth factor-stimulated ERK1 and ERK2 activity. Similarly, stimulation of ERK1 and ERK2 activity by insulin-like growth factor I was reduced when IQGAP1 levels were changed. In contrast, overexpression of an IQGAP1 construct lacking the ERK2 binding region did not interfere with activation of ERK1 and ERK2 by epidermal growth factor. Our data disclose a previously unidentified communication between IQGAP1 and the ERK pathway and imply that IQGAP1 modulates the Ras/mitogen-activated protein kinase signaling cascade.
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Affiliation(s)
- Monideepa Roy
- Department of Pathology, Brigham, and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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28
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Abstract
The dynamic processes of cell migration and invasion are largely coordinated by Rho family GTPases. The scaffolding protein IQGAP1 binds to Cdc42, increasing the amount of active Cdc42 both in vitro and in cells. Here we show that overexpression of IQGAP1 in mammalian cells enhances cell migration in a Cdc42- and Rac1-dependent manner. Importantly, cell motility was significantly decreased both by knock down of endogenous IQGAP1 using small interfering RNA and by transfection of a dominant negative IQGAP1 construct, IQGAP1DeltaGRD. Cell invasion was similarly altered by manipulating intracellular IQGAP1 concentrations. Moreover, invasion mediated by constitutively active Cdc42 was attenuated by IQGAP1DeltaGRD. Thus, IQGAP1 has a fundamental role in cell motility and invasion.
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Affiliation(s)
- Jennifer M Mataraza
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School Boston, Massachusetts 02115, USA
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29
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Abstract
IQGAP1, is a recently discovered scaffold protein proposed to regulate membrane cytoskeleton events through protein-protein interactions with F-actin, E-cadherin, beta-catenin, and CLIP170. The binding of IQGAP1 to its partners is regulated by calcium/calmodulin (Ca(++)/CaM) and the small molecular weight guanine nucleotide triphosphatases (GTPases), Cdc42, and Rac1. Here we identify a novel IQGAP1 scaffolding function by isolating the cyclic AMP dependent kinase (PKA) with IQGAP1. IQGAP1 was co-purified with PKA using 5'-cyclic AMP (cAMP) affinity chromatography and PKA activity was co-immunoprecipitated with IQGAP1 using an anti-IQGAP1 antibody. The association of IQGAP1 with PKA was shown to occur through a direct interaction between A kinase anchoring protein 79 (AKAP79) and the carboxyl-terminal domain of IQGAP1. This suggests that cAMP/PKA may be coupled with Ca(++)/CaM and GTPases through an IQGAP1/AKAP79 complex.
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Affiliation(s)
- J Brian Nauert
- Division of Endocrinology, Diabetes and Clinical Nutrition, Oregon Health and Science University, L607 Portland, Oregon, USA
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30
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Mateer SC, Wang N, Bloom GS. IQGAPs: integrators of the cytoskeleton, cell adhesion machinery, and signaling networks. Cell Motil Cytoskeleton 2003; 55:147-55. [PMID: 12789660 DOI: 10.1002/cm.10118] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Scott C Mateer
- Department of Biology, University of Virginia, Charlottesville 22903, USA
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31
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Abstract
IQGAP1 is a scaffolding protein that binds to a diverse array of signalling and structural molecules. By interacting with its target proteins, human IQGAP1 participates in multiple cellular functions, including Ca(2+)/calmodulin signalling, cytoskeletal architecture, CDC42 and Rac signalling, E-cadherin-mediated cell-cell adhesion and beta-catenin-mediated transcription. Yeast IQGAP homologues are important regulators of cellular morphogenesis because they are required for budding and cytokinesis. Here we discuss the structure and function of IQGAP1 as a member of the family of IQGAP proteins and summarize the current knowledge about IQGAP1 and IQGAP2. Collectively, these data reveal that IQGAP1 is a fundamental regulator of cytoskeletal function.
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Affiliation(s)
- Michael W. Briggs
- Brigham and Women's Hospital, Thorn 530, 75 Francis Street, Boston, Massachusetts 02115, USA
| | - David B. Sacks
- Brigham and Women's Hospital, Thorn 530, 75 Francis Street, Boston, Massachusetts 02115, USA
- Tel:+1 617 732 6627; Fax: +1 617 278 6921;
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32
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Abstract
IQGAP1 is a multi-domained protein that integrates signaling of the Rho family GTPase Cdc42 with regulation of the cytoskeleton. Using SPOT analysis and in vitro peptide competition assays we have identified a 24 amino acid region of IQGAP1 that is necessary for Cdc42 binding. Both in vitro and in vivo analyses reveal that deletion of this sequence abolishes binding of IQGAP1 to Cdc42. In addition, the ability of IQGAP1 to increase the amount of active Cdc42 in cells is abrogated upon removal of this region. An IQGAP1 mutant lacking the Cdc42 binding site mislocalizes to the cell periphery. These observations specifically define a short sequence of IQGAP1 that is required for its interaction with Cdc42 and demonstrate that Cdc42 binding is necessary for the normal subcellular distribution of IQGAP1.
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Affiliation(s)
- Jennifer M Mataraza
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Thorn 530, 75 Francis Street Boston, MA 02115, USA
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33
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Abstract
A family of proteins known as IQGAPs have been identified in yeast, amebas and mammals. IQGAPs are multidomain molecules that contain several protein-interacting motifs which mediate binding to target proteins. Mammalian IQGAP1 is a component of signaling networks that are integral to maintaining cytoskeletal architecture and cell-cell adhesion. Published data suggest that IQGAP1 is a scaffolding protein that modulates cross-talk among diverse pathways in complex regulatory circuits. These pathways include modulating the actin cytoskeleton, mediating signaling by Rho family GTPases and calmodulin, regulating E-cadherin and beta-catenin function and organizing microtubules.
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Affiliation(s)
- Michael W Briggs
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Thorn 530, 75 Francis Street, Boston, MA 02115, USA
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34
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Yamashiro S, Noguchi T, Mabuchi I. Localization of two IQGAPs in cultured cells and early embryos of Xenopus laevis. Cell Motil Cytoskeleton 2003; 55:36-50. [PMID: 12673597 DOI: 10.1002/cm.10109] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mammalian IQGAP1 is considered to modulate organization of the actin cytoskeleton under regulation of signaling proteins Cdc42 or Rac and calmodulin [Bashour et al., 1997: J Cell Biol 137:1555-1566; Hart et al., 1996: EMBO J 15:2997-3005] and also to be involved in cadherin-based cell adhesion [Kuroda et al., 1998: Science 281:832-835]. However, its function in the cell has not been clear. In order to clarify the function of IQGAP, we investigated IQGAP in Xenopus laevis cells. We isolated two Xenopus cDNAs encoding homologues of mammalian IQGAP, XIQGAP1, and XIQGAP2, which show high homology with human IQGAP1 and IQGAP2, respectively. Immunofluorescent localization of XIQGAPs in Xenopus tissue cultured cells (XTC cells) and in developing embryos was examined. In XTC cells, XIQGAP1 was colocalized with F-actin at cell-to-cell contact sites, membrane ruffles in lamellipodia, and filopodia. During development of embryos, XIQGAP1 was concentrated in the borders of all embryonic cells. An intense staining for XIQGAP1 was found in regions undergoing active morphogenetic movements, such as the blastopore lip of gastrulae, and the neural plate, the notochord, and the somite of neurulae. These results suggest that XIQGAP1 is involved in both cell-to-cell adhesion and cell migration during Xenopus embryogenesis and in cultured cells. On the other hand, the localization of XIQGAP2 in XTC cells was distinct from that of XIQGAP1 although it was also seen in lamellipodia, filopodia, and borders between cells. In addition to these regions, strong nuclear staining was observed in both XTC cells and embryonic cells.
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Affiliation(s)
- Sawako Yamashiro
- Division of Biology, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
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35
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Schmidt VA, Scudder L, Devoe CE, Bernards A, Cupit LD, Bahou WF. IQGAP2 functions as a GTP-dependent effector protein in thrombin-induced platelet cytoskeletal reorganization. Blood 2003; 101:3021-8. [PMID: 12515716 DOI: 10.1182/blood-2002-09-2807] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human blood platelets are anucleate cells whose response to extracellular stimuli results in actin cytoskeleton rearrangements, thereby providing the critical initial step in the regulation of hemostasis. The serine protease alpha-thrombin, known to activate platelets by cleavage of a family of protease-activated receptors (PARs), is the most potent physiologic activator of human platelets, though downstream effector proteins uniquely linked to platelet cytoskeletal actin polymerization remain largely uncharacterized. The gene encoding the putative rac1/cdc42 effector protein IQGAP2 was identified within the PAR gene cluster at 5q13, flanked telomeric by PAR1 and encompassing PAR3. Immunofluorescence microscopy demonstrated IQGAP2 expression in filopodial extensions of activated platelets and colocalized with F-actin in lamellipodia and filopodia of IQGAP2-transfected COS1 cells. Platelet activation by alpha-thrombin, but not saturating concentrations of fibrillar collagen or adenosine 5'-diphosphate, uniquely assemble an IQGAP2/arp2/3-actin cytoplasmic complex, an association regulated by guanosine triphosphate rac1 ([GTP]rac1) but not by [GTP]cdc42. Likewise, only thrombin-activated platelets resulted in rapid translocation of IQGAP2 to the platelet cytoskeleton. These observations identify a physiologic scaffolding function for IQGAP2 and establish the presence of a functional genomic unit in humans uniquely evolved to regulate thrombin-induced platelet cytoskeletal actin reorganization.
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Affiliation(s)
- Valentina A Schmidt
- Department of Medicine and the Program in Genetics, State University of New York, Stony Brook, 11794, USA
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36
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Katata T, Irie K, Fukuhara A, Kawakatsu T, Yamada A, Shimizu K, Takai Y. Involvement of nectin in the localization of IQGAP1 at the cell-cell adhesion sites through the actin cytoskeleton in Madin-Darby canine kidney cells. Oncogene 2003; 22:2097-109. [PMID: 12687012 DOI: 10.1038/sj.onc.1206255] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
IQGAP1, a putative downstream target of the Rho family small G proteins, Cdc42 and Rac, localizes at adherens junctions (AJs) in epithelial cells. It has been suggested that IQGAP1 localizes at AJs through its binding to beta-catenin, and negatively regulates the E-cadherin-mediated cell-cell adhesion. Nectin is a Ca(2+)-independent, immunoglobulin-like cell-cell adhesion molecule that localizes at AJs. Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs cooperatively with E-cadherin. Here we investigated a role of nectin in the localization of IQGAP1 at AJs. Ca(2+) chelation from the medium causes disruption of the E-cadherin-mediated cell-cell adhesion, but not the nectin-based cell-cell adhesion, in Madin-Darby canine kidney (MDCK) cells. IQGAP1 remained at the residual nectin-based cell-cell adhesion sites where the E-cadherin immunofluorescence signal disappeared. Restoration of Ca(2+) in the medium causes re-accumulation of E-cadherin to the residual nectin-based cell-cell adhesion sites to re-form AJs. Nectin inhibitors inhibit this re-accumulation of E-cadherin to re-form AJs by impairing the nectin-based cell-cell adhesion. The nectin inhibitors also reduced the localization of IQGAP1 at the cell-cell adhesion sites. When MDCK cells were incubated with microbeads coated with the extracellular fragment of nectin that interacts with cellular nectin, IQGAP1 also accumulated at the bead-MDCK cell contact sites. The accumulation of IQGAP1 at the cell-cell adhesion sites was inhibited by actin filament-disrupting agents, latrunculin A and cytochalasin D. These results indicate that nectin is involved in the localization of IQGAP1 at AJs through the actin cytoskeleton.
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Affiliation(s)
- Tatsuo Katata
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, Japan
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Presslauer S, Hinterhuber G, Cauza K, Horvat R, Rappersberger K, Wolff K, Foedinger D. RasGAP-like protein IQGAP1 is expressed by human keratinocytes and recognized by autoantibodies in association with bullous skin disease. J Invest Dermatol 2003; 120:365-71. [PMID: 12603848 DOI: 10.1046/j.1523-1747.2003.12070.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Autoantibodies in patients with autoimmune bullous skin diseases, such as pemphigus or bullous pemphigoid are of diagnostic value and might play a part in the pathogenic scenario. In this study we present five patients with erythematous plaques, subepidermal blister formation of the skin, and the presence of circulating autoantibodies directed against a so far unrecognized 190 kDa antigen in human keratinocytes. Amino acid sequence analysis identified the protein as IQGAP1, a recently described human Ras GTPase-activating-like protein suspected to act as an effector molecule for Cdc42 and Rac1, members of the Rho small GTPase family and to play a key part in regulating E-cadherin-mediated cell adhesion. The protein is selectively recognized by a monoclonal anti-IQGAP1 antibody on western blots and immunoprecipitates from keratinocyte extracts. Indirect immunofluorescence locates IQGAP1 within individual keratinocytes in a cytoplasmic pattern and along the cell periphery at adhesive sites. Our results demonstrate IQGAP1, a newly described multifunctional protein, to be constitutively expressed in human keratinocytes where it may contribute to the integrity of the epidermal layer. Furthermore, we found autoantibodies reacting with IQGAP1 in patients with bullous skin eruptions most apparently belonging to the spectrum of bullous pemphigoid.
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Affiliation(s)
- Stefan Presslauer
- Department of Dermatology, Division of General Dermatology, University of Vienna, School of Medicine, Vienna, Austria
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38
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Zhou R, Guo Z, Watson C, Chen E, Kong R, Wang W, Yao X. Polarized distribution of IQGAP proteins in gastric parietal cells and their roles in regulated epithelial cell secretion. Mol Biol Cell 2003; 14:1097-108. [PMID: 12631726 PMCID: PMC151582 DOI: 10.1091/mbc.e02-07-0425] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Actin cytoskeleton plays an important role in the establishment of epithelial cell polarity. Cdc42, a member of Rho GTPase family, modulates actin dynamics via its regulators, such as IQGAP proteins. Gastric parietal cells are polarized epithelial cells in which regulated acid secretion occurs in the apical membrane upon stimulation. We have previously shown that actin isoforms are polarized to different membrane domains and that the integrity of the actin cytoskeleton is essential for acid secretion. Herein, we show that Cdc42 is preferentially distributed to the apical membrane of gastric parietal cells. In addition, we revealed that two Cdc42 regulators, IQGAP1 and IQGAP2, are present in gastric parietal cells. Interestingly, IQGAP2 is polarized to the apical membrane of the parietal cells, whereas IQGAP1 is mainly distributed to the basolateral membrane. An IQGAP peptide that competes with full-length IQGAP proteins for Cdc42-binding in vitro also inhibits acid secretion in streptolysin-O-permeabilized gastric glands. Furthermore, this peptide disrupts the association of IQGAP and Cdc42 with the apical actin cytoskeleton and prevents the apical membrane remodeling upon stimulation. We propose that IQGAP2 forms a link that associates Cdc42 with the apical cytoskeleton and thus allows for activation of polarized secretion in gastric parietal cells.
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Affiliation(s)
- Rihong Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA
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Abstract
Calmodulin regulates the function of numerous proteins by binding to short regions on the target molecule. IQ motifs, which are found in over 100 human proteins, appear in tandem repeats and bind calmodulin in the absence of Ca(2+). One of these IQ-containing proteins, IQGAP1, interacts with several targets, including Cdc42, beta-catenin, E-cadherin, and actin, in a calmodulin-regulated manner. To elucidate the molecular mechanism by which apocalmodulin and Ca(2+)/calmodulin differentially regulate IQGAP1, a series of constructs of IQGAP1 with selected point mutations of the four tandem IQ motifs were generated. Mutating the basic charged arginine residues in all four IQ motifs abrogated binding of IQGAP1 to apocalmodulin, but had no effect on its interaction with Ca(2+)/calmodulin. Analysis of IQGAP1 constructs with point mutations in single, double, or triple IQ motifs revealed that apocalmodulin bound only to IQ3 and IQ4. By contrast to the arginine mutant constructs, mutation of selected hydrophobic residues in the IQ motifs produced an IQGAP1 protein incapable of binding either apocalmodulin or Ca(2+)/calmodulin. These results, which differ from the conventional model of Ca(2+)-independent binding of calmodulin to IQ motifs, provide insight into the complexity of the molecular interactions between calmodulin and IQ motifs.
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Affiliation(s)
- Zhigang Li
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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40
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Mbele GO, Deloulme JC, Gentil BJ, Delphin C, Ferro M, Garin J, Takahashi M, Baudier J. The zinc- and calcium-binding S100B interacts and co-localizes with IQGAP1 during dynamic rearrangement of cell membranes. J Biol Chem 2002; 277:49998-50007. [PMID: 12377780 DOI: 10.1074/jbc.m205363200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Zn(2+)- and Ca(2+)-binding S100B protein is implicated in multiple intracellular and extracellular regulatory events. In glial cells, a relationship exists between cytoplasmic S100B accumulation and cell morphological changes. We have identified the IQGAP1 protein as the major cytoplasmic S100B target protein in different rat and human glial cell lines in the presence of Zn(2+) and Ca(2+). Zn(2+) binding to S100B is sufficient to promote interaction with IQGAP1. IQ motifs on IQGAP1 represent the minimal interaction sites for S100B. We also provide evidence that, in human astrocytoma cell lines, S100B co-localizes with IQGAP1 at the polarized leading edge and areas of membrane ruffling and that both proteins relocate in a Ca(2+)-dependent manner within newly formed vesicle-like structures. Our data identify IQGAP1 as a potential target protein of S100B during processes of dynamic rearrangement of cell membrane morphology. They also reveal an additional cellular function for IQGAP1 associated with Zn(2+)/Ca(2+)-dependent relocation of S100B.
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Affiliation(s)
- Gaelh Ouengue Mbele
- Département Réponse et Différenciation Cellulaires du Commissariat à l'Energie Atomique (CEA), INSERM EMI-0104 DRDC-TS, Grenoble 38054, France
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Matsumoto Y, Oshida T, Obayashi I, Imai Y, Matsui K, Yoshida NL, Nagata N, Ogawa K, Obayashi M, Kashiwabara T, Gunji S, Nagasu T, Sugita Y, Tanaka T, Tsujimoto G, Katsunuma T, Akasawa A, Saito H. Identification of highly expressed genes in peripheral blood T cells from patients with atopic dermatitis. Int Arch Allergy Immunol 2002; 129:327-40. [PMID: 12483038 DOI: 10.1159/000067589] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Analysis of genes that are differentially expressed in patients with atopic dermatitis (AD) and normal individuals will provide important information on the underlying molecular pathogenetic mechanisms of AD. METHODS Transcript of freshly isolated peripheral blood T cells from 59 individuals were analyzed with a fluorescent differential display (FDD) method. Ninety-two differentially expressed genes were identified in this manner. Additionally, real-time quantitative RT-PCR was employed to investigate the expression of the FDD-selected genes and also genes related to T cell function. RESULTS A number of genes, including CC chemokine receptor 4, T cell-specific tyrosine kinase (Emt/Itk), integrin beta1, integrin alpha6, IQGAP1 and MAR/SAR DNA-binding protein (SATB1), were shown to be more highly expressed in patients with moderate and/or severe AD than in controls or patients with mild AD. Because the products of these upregulated genes influence chemotaxis, adhesion, migration and Th2 polarization, it is suggested that in more severe AD, circulating T cells may function differently in this regard. Several other genes, the role of which in T cell function is currently unknown, were also found to be differentially expressed in AD. These included the heat shock protein 40 and vasopressin-activated calcium-mobilizing receptor 1. CONCLUSION The upregulated genes identified in this work may serve as useful markers for moderate to severe AD as opposed to normal or mild AD and also as markers indicating progression to more severe AD. Further functional characterization will provide a better understanding of the pathophysiology of circulating T cells in AD.
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Affiliation(s)
- Yoshiko Matsumoto
- Genox Research, Inc., Teikyo University Biotech Center, Kawasaki, Kanagawa, Japan
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Abstract
Cytokinesis requires the polarization of the actin cytoskeleton, the secretion machinery, and the correct positioning of the division axis. Budding yeast cells commit to their cytokinesis plane by choosing a bud site and polarizing their growth. Iqg1p (Cyk1p) was previously implicated in cytokinesis (Epp and Chant, 1997; Lippincott and Li, 1998; Osman and Cerione, 1998), as well as in the establishment of polarity and protein trafficking (Osman and Cerione, 1998). To better understand how Iqg1p influences these processes, we performed a two-hybrid screen and identified the spatial landmark Bud4p as a binding partner. Iqg1p can be coimmunoprecipitated with Bud4p, and Bud4p requires Iqg1p for its proper localization. Iqg1p also appears to specify axial bud-site selection and mediates the proper localization of the septin, Cdc12p, as well as binds and helps localize the secretion landmark, Sec3p. The double mutants iqg1Deltasec3Delta and bud4Deltasec3Delta display defects in polarity, budding pattern and cytokinesis, and electron microscopic studies reveal that these cells have aberrant septal deposition. Taken together, these findings suggest that Iqg1p recruits landmark proteins to form a targeting patch that coordinates axial budding with cytokinesis.
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Affiliation(s)
- Mahasin A Osman
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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43
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Abstract
Adherens junction formation is fundamental for compaction and trophectoderm differentiation during mammalian preimplantation development. We recently isolated an IQGAP-2 cDNA from a differential display-polymerase chain reaction screen of bovine preimplantation developmental stages. IQGAP-1 and -2 proteins mediate E-cadherin-based cell-to-cell adhesion through interactions with beta-catenin and the Rho GTPases, rac1 and cdc42. Our study demonstrates IQGAP-1,-2, rac-1 and cdc42 mRNAs are present throughout murine preimplantation development. IQGAP-1 and rac-1 protein distribution changes from predominantly plasma membrane associated to predominantly cytoplasmic as the embryo progresses through cleavage divisions and compaction to the blastocyst stage.
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Affiliation(s)
- David R Natale
- Department of Physiology and Pharmacology University of Western Ontario, Ontario, London, Canada N6A 5C1
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44
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Abstract
In filamentous ascomycetes hyphae are compartmentalized by septation in which the cytoplasm of the compartments are interconnected via septal pores. Thus, septation in filamentous fungi is different from cytokinesis in yeast like fungi. We have identified an Ashbya gossypii orthologue of the Saccharomyces cerevisiae CYK1 gene which belongs to the IQGAP-protein family. In contrast to S. cerevisiae disruption of AgCYK1 yields viable mutant strains that exhibit wildtype-like polarized hyphal growth rates. In the Agcyk1 mutant cortical actin patches localize to growing hyphal tips like wildtype, however, mutant hyphae are totally devoid of actin rings at presumptive septal sites. Septation in wildtype results in the formation of chitin rings. Agcyk1 mutant hyphae are aseptate and do not accumulate chitin in their cell walls. Agcyk1 mutant strains are completely asporogenous indicating that septation is essential for the formation of sporangia in A. gossypii. AgCyk1p-GFP localizes to sites of future septation as a ring prior to chitin depositioning. Furthermore, decrease in Cyk1p-ring diameter was found to be a prerequisite for the accumulation of chitin and septum formation.
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Affiliation(s)
- Jürgen Wendland
- Department of Microbiology, Friedrich-Schiller University, Winzerlaer Str. 10, Jena, Germany.
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45
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Abstract
Rho GTPases regulate microtubule capture near the cell cortex to polarize cells. What is surprising is the repertoire of interactions between proteins at the ends of microtubules and their cortical targets. The microtubule tip protein CLIP-170 has now been found to interact with the Cdc42/Rac effector IQGAP and mediate transient capture of microtubules.
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Affiliation(s)
- Gregg G Gundersen
- Department of Anatomy & Cell Biology, Columbia University, New York, NY 10032, USA.
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46
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Ruiz-Velasco R, Lanning CC, Williams CL. The activation of Rac1 by M3 muscarinic acetylcholine receptors involves the translocation of Rac1 and IQGAP1 to cell junctions and changes in the composition of protein complexes containing Rac1, IQGAP1, and actin. J Biol Chem 2002; 277:33081-91. [PMID: 12070151 DOI: 10.1074/jbc.m202664200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The abilities of the M(3) muscarinic acetylcholine receptor (mAChR) and Rac1 to regulate similar cellular responses, including cadherin-mediated adhesion, prompted us to investigate Rac1 regulation by M(3) mAChR. We characterized changes in Rac1 induced by stimulating transfected M(3) mAChR in Chinese hamster ovary cells stably expressing hemagglutinin (HA)-tagged wild-type or mutant Rac1. mAChR activation converts endogenous Rac1 to the GTP-bound form in cells expressing HA-Rac1 but not in cells expressing dominant negative HA-Rac1(Asn-17) or constitutively active HA-Rac1(Val-12). The competitive binding of endogenous IQGAP1 by HA-Rac1(Val-12) may diminish the mAChR-mediated activation of endogenous Rac1. HA-Rac1 and HA-Rac1(Val-12), but not HA-Rac1(Asn-17), accumulate with IQGAP1 at cell junctions during mAChR-induced cell-cell compaction. Co-localization studies suggest that Rac1 can accumulate at junctions without IQGAP1, but IQGAP1 cannot accumulate at junctions without Rac1. mAChR activation also induces GTP-independent changes in Rac1 because mAChR activation redistributes HA-Rac1(Asn-17), which does not bind GTP. Actin associates with complexes containing HA-Rac1 or HA-Rac1(Val-12) after prolonged mAChR activation. We also demonstrate that Rac1 participates in mAChR-induced cell-cell compaction and c-Jun phosphorylation. These results indicate that M(3) mAChR activation converts Rac1 to the GTP-bound form, alters interactions between Rac1, IQGAP1, and actin, and causes the junctional accumulation of Rac1 and IQGAP1.
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Affiliation(s)
- Rebecca Ruiz-Velasco
- Molecular Pharmacology Laboratory, Guthrie Research Institute, One Guthrie Square, Sayre, Pennsylvania 18840, USA
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47
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Shimao Y, Nabeshima K, Inoue T, Koono M. Complex formation of IQGAP1 with E-cadherin/catenin during cohort migration of carcinoma cells. Its possible association with localized release from cell-cell adhesion. Virchows Arch 2002; 441:124-32. [PMID: 12189501 DOI: 10.1007/s00428-002-0603-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2001] [Accepted: 12/10/2001] [Indexed: 10/27/2022]
Abstract
In histopathological sections, it is frequently observed that carcinoma cells invade the stroma as coherent cell nests rather than single cells. We have called this type of movement "cohort migration (CM)" and developed an in vitro model, in which human colon carcinoma cells move as coherent cell sheets when stimulated with hepatocyte growth factor/scatter factor (HGF/SF). In this CM model, localized release from cell-cell adhesion at the lower portion of cells is essential for cell movement. Its mechanism was investigated in this study with special reference to the E-cadherin/catenin complex (Ecc) and IQGAP1. IQGAP1 is a target molecule of Cdc42 and Rac1 and negatively regulates the Ecc-based cell-cell adhesion by dissociating alpha-catenin, a key molecule that links Ecc to actin cytoskeleton, from Ecc. In our study, the amount of IQGAP1 bound to Ecc increased in migrating cells in association with a decrease in the alpha-catenin level in Ecc. In accordance with this, IQGAP1 showed a shift from the cytosol to the membrane fraction. Moreover, confocal laser microscopic study demonstrated the localization of IQGAP1 at the membranes of the lower portion of migrating cells, where cell-cell adhesion was specifically disrupted during CM. Furthermore, when HGF/SF-induced CM was enhanced with pre-coated extracellular matrix (ECM) components, the level of IQGAP1 in Ecc increased more than that caused by HGF/SF alone. On the contrary, when CM was inhibited by interrupting cell-ECM interaction, the level of IQGAP1 in Ecc did not increase despite HGF/SF stimulation. Taken together, these results indicate close association of IQGAP1 with localized disruption of cell-cell adhesion during CM and that modulation of CM by cross-talk between signals induced by HGF/SF and cell-ECM interactions also involves IQGAP1-related mechanisms.
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Affiliation(s)
- Yoshiya Shimao
- Department of Pathology, Miyazaki Medical Collage Hospital, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
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48
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Abstract
The Ras-GAP related protein IQGAP1 binds several proteins, including actin, calmodulin, E-cadherin and the Rho family GTPase Cdc42. To gain insight into its in vivo function, IQGAP1 was overexpressed in mammalian cells. Transfection of IQGAP1 significantly increased the levels of active, GTP-bound Cdc42, resulting in the formation of peripheral actin microspikes. By contrast, transfection of an IQGAP1 mutant lacking part of the GAP-related domain (IQGAP1deltaGRD) substantially decreased the amount of GTP-bound Cdc42 in cell lysates. Consistent with these findings, IQGAP1DeltaGRD blocked Cdc42 function in cells that stably overexpress constitutively active Cdc42 and abrogated the effect of bradykinin on Cdc42. In cells transfected with IQGAP1deltaGRD, bradykinin was unable to activate Cdc42, translocate Cdc42 to the membrane fraction, or induce filopodia production. IQGAP1deltaGRD transfection altered cellular morphology, producing small, round cells that closely resemble Cdc42-/- cells. Some insight into the mechanism was provided by in vitro analysis, which revealed that IQGAP1deltaGRD increased the intrinsic GTPase activity of Cdc42, thereby increasing the amount of inactive, GDP-bound Cdc42. These data imply that IQGAP1 has a crucial role in transducing Cdc42 signaling to the cytoskeleton.
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Affiliation(s)
- Jennifer M Swart-Mataraza
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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49
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Abstract
In migrating cells, Rho family GTPases and their effectors play a central role in polarizing and in organizing the actin and microtubule cytoskeletons. A study by Fukata et al. in the June 28th issue of Cell now shows that the Rac1/Cdc42 effector IQGAP1 captures microtubules by binding to CLIP170.
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Affiliation(s)
- Damian Brunner
- Cell Biology and Cell Biophysics Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117, Heidelberg, Germany
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50
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Fukata M, Watanabe T, Noritake J, Nakagawa M, Yamaga M, Kuroda S, Matsuura Y, Iwamatsu A, Perez F, Kaibuchi K. Rac1 and Cdc42 capture microtubules through IQGAP1 and CLIP-170. Cell 2002; 109:873-85. [PMID: 12110184 DOI: 10.1016/s0092-8674(02)00800-0] [Citation(s) in RCA: 481] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Linkage of microtubules to special cortical regions is essential for cell polarization. CLIP-170 binds to the growing ends of microtubules and plays pivotal roles in orientation. We have found that IQGAP1, an effector of Rac1 and Cdc42, interacts with CLIP-170. In Vero fibroblasts, IQGAP1 localizes at the polarized leading edge. Expression of carboxy-terminal fragment of IQGAP1, which includes the CLIP-170 binding region, delocalizes GFP-CLIP-170 from the tips of microtubules and alters the microtubule array. Activated Rac1/Cdc42, IQGAP1, and CLIP-170 form a tripartite complex. Furthermore, expression of an IQGAP1 mutant defective in Rac1/Cdc42 binding induces multiple leading edges. These results indicate that Rac1/Cdc42 marks special cortical spots where the IQGAP1 and CLIP-170 complex is targeted, leading to a polarized microtubule array and cell polarization.
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Affiliation(s)
- Masaki Fukata
- Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, Aichi 466-8550, Japan
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