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Li X, Zhao X, Su X, Wen J, Yang S, Qin Y, Yan S, Yao Y, Li X, Wang X. IQGAP1 overexpression attenuates chemosensitivity through YAP-mediated ferroptosis inhibition in esophageal squamous cell cancer cells. Arch Biochem Biophys 2024; 758:110064. [PMID: 38897534 DOI: 10.1016/j.abb.2024.110064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 05/30/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024]
Abstract
Chemoresistance is one of the major hindrances to many cancer therapies, including esophageal squamous cell carcinoma (ESCC). Ferroptosis, a new programmed cell death, plays an essential role in chemoresistance. IQ-domain GTPase activating protein 1 (IQGAP1) is a scaffold protein and functions as an oncogene in various human malignancies. However, the underlying effect and molecular mechanisms of IQGAP1 on paclitaxel (PTX) resistance and ferroptosis in ESCC remain to be elucidated. In this study, we found that IQGAP1 was highly expressed in ESCC tissues and could as a potential biomarker for diagnosis and predicting the prognosis of ESCC. Functional studies revealed that IQGAP1 overexpression reduced the sensitivity of ESCC cells to PTX by enhancing ESCC cell viability and proliferation and inhibiting cell death, and protected ESCC cells from ferroptosis, whereas IQGAP1 knockdown exhibited contrary effects. Importantly, reductions of chemosensitivity and ferroptosis caused by IQGAP1 overexpression were reversed with ferroptosis inducer RSL3, while the increases of chemosensitivity and ferroptosis caused by IQGAP1 knockdown were reversed with ferroptosis inhibitor ferrostatin-1 (Fer-1) in ESCC cells, indicating that IQGAP1 played a key role in resistance to PTX through regulating ferroptosis. Mechanistically, we demonstrated that IQGAP1 overexpression upregulated the expression of Yes-associated protein (YAP), the central mediator of the Hippo pathway. YAP inhibitor Verteporfin (VP) could reverse the effects of IQGAP1 overexpression on ESCC chemoresistance and ferroptosis. Taken together, our findings suggest that IQGAP1 promotes chemoresistance by blocking ferroptosis through targeting YAP. IQGAP1 may be a novel therapeutic target for overcoming chemoresistance in ESCC.
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Affiliation(s)
- Xinting Li
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China; Heji Hospital Affiliated to Changzhi Medical College, Changzhi, Shanxi, 046000, China
| | - Xinran Zhao
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Xingxing Su
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Jie Wen
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Shuya Yang
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Yi Qin
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Shuxin Yan
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Yijian Yao
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China
| | - Xiaozhong Li
- Department of Infectious Diseases, Shanxi Provincial People's Hospital, Fifth Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030012, China.
| | - Xiaoxia Wang
- Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan, Shanxi, 030001, China.
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Jurado M, Zorzano A, Castaño O. Cooperativity and oscillations: Regulatory mechanisms of K-Ras nanoclusters. Comput Biol Med 2023; 166:107455. [PMID: 37742420 DOI: 10.1016/j.compbiomed.2023.107455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 08/07/2023] [Accepted: 09/04/2023] [Indexed: 09/26/2023]
Abstract
K-Ras nanoclusters (NCs) concentrate all required molecules belonging to the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway in a small area where signaling events take place, increasing efficiency and specificity of signaling. Such nanostructures are characterized by controlled sizes and lifetimes distributions, but there is a poor understanding of the mechanisms involved in their dynamics of growth/decay. Here, a minimum computational model is presented to analyze the behavior of K-Ras NCs as cooperative dynamic structures that self-regulate their growth and decay according to their size. Indeed, the proposed model reveals that the growth and the local production of a K-Ras nanocluster depend positively on its actual size, whilst its lifetime is inversely proportional to the root of its size. The cooperative binding between the structural constituents of the NC (K-Ras proteins) induces oscillations in the size distributions of K-Ras NCs allowing them to range within controlled values, regulating the growth/decay dynamics of these NCs. Thereby, the size of a K-Ras NC is proposed as a key factor to regulate cell signaling, opening a range of possibilities to develop strategies for use in chronic diseases and cancer.
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Affiliation(s)
- Manuel Jurado
- Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; CIBER of Diabetes and Associated Metabolic Diseases, Barcelona, Spain; Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain.
| | - Oscar Castaño
- Electronics and Biomedical Engineering, Universitat de Barcelona (UB), Barcelona, Spain; Nanobioengineering and Biomaterials, Institute of Nanoscience and Nanotechnology of the University of Barcelona, Barcelona, Spain
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3
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Hou L, Voit RA, Shibamura-Fujiogi M, Koutsogiannaki S, Li Y, Chen Y, Luo H, Sankaran VG, Yuki K. CD11c regulates neutrophil maturation. Blood Adv 2023; 7:1312-1325. [PMID: 36306384 PMCID: PMC10119615 DOI: 10.1182/bloodadvances.2022007719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 09/14/2022] [Accepted: 09/27/2022] [Indexed: 11/20/2022] Open
Abstract
Sepsis continues to be associated with high morbidity and mortality. Currently, sepsis is managed only conservatively. In sepsis, a substantial number of neutrophils is required, leading to accelerated neutrophil production. Immature neutrophils are released into the circulation to meet a demand, despite their less effective functioning in microbial eradication. Although an intervention to provide more mature neutrophils may serve as a potential sepsis treatment, the mechanism of neutrophil differentiation and maturation remains poorly understood. We discovered that CD11c, traditionally known as a dendritic cell marker, was expressed in neutrophils and regulated neutrophil maturation and effector functions. In the absence of CD11c, neutrophil maturation was impaired in the bone marrow, concomitant with a significant increase in the proliferation and apoptosis of preneutrophils, associated with less effector functions. Under lipopolysaccharide challenge, inducing an emergent neutrophil production in the bone marrow, CD11c deficiency exaggerated the release of immature neutrophils into the circulation, associated with a significant proliferation and apoptosis of preneutrophils. In contrast, constitutively active CD11c knock-in mice showed accelerated neutrophil maturation associated with enhanced effector functions, which further supports the notion that CD11c regulates neutrophil maturation. Furthermore, the constitutively active CD11c knock-in mice offered enhanced bacterial eradication. Taken together, we discovered that CD11c was critical for the regulation of neutrophil maturation, and CD11c activation could serve as a potential target for sepsis treatment.
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Affiliation(s)
- Lifei Hou
- Cardiac Anesthesia Division, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA
- Department of Anaesthesia and Immunology, Harvard Medical School, Boston, MA
| | - Richard A. Voit
- Department of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Miho Shibamura-Fujiogi
- Cardiac Anesthesia Division, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA
- Department of Anaesthesia and Immunology, Harvard Medical School, Boston, MA
| | - Sophia Koutsogiannaki
- Cardiac Anesthesia Division, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA
- Department of Anaesthesia and Immunology, Harvard Medical School, Boston, MA
| | - Yunan Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN
| | - Yue Chen
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN
| | - Hongbo Luo
- Department of Pathology, Boston Children’s Hospital, Boston, MA
| | - Vijay G. Sankaran
- Department of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
| | - Koichi Yuki
- Cardiac Anesthesia Division, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA
- Department of Anaesthesia and Immunology, Harvard Medical School, Boston, MA
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TAGLN2 Promotes the Proliferation, Migration, Invasion, and EMT of Clear Cell Renal Cell Carcinoma Through the PI3K/Akt Signaling Pathway. Biochem Genet 2022:10.1007/s10528-022-10319-z. [PMID: 36547768 DOI: 10.1007/s10528-022-10319-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
The effect of Transgelin 2 (TAGLN2) on clear cell renal cell carcinoma (ccRCC) is unknown. This study explored the potential role and mechanism of ccRCC. The expression of TAGLN2 in Pan-cancers was analyzed using the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases. TCGA-KIRC database was used to analyze subsequent prognostic survival, pathway enrichment, and immune infiltration. Relevant experimental methods could explain the effect of TAGLN2 expression on tumor cell proliferation, migration, invasion, and apoptosis. Apoptosis, proliferation, Epithelial-to-Mesenchymal Transition (EMT), and PI3K/AKT signaling pathway-related protein expression were determined through western blotting. In the TCGA + GTEx database, mRNA-TAGLN2 expression was clearly increased in pan-cancer tissues, and the same result was found in ccRCC patients based on KIRC analysis results. In addition, TAGLN2 was associated with poor clinical stage, pathological grade, and survival prognosis. TAGLN2 is highly expressed in ccRCC tissues and in vitro TAGLN2 silencing of cells inhibits the proliferation, migration, invasion, and EMT of ccRCC cancer cells. Furthermore, TAGLN2-related differential genes enriched in the PI3K/AKT signaling pathway were negatively regulated after TAGLN2 silencing. Moreover, TAGLN2 may promote tumor immune escape and increase the risk of distant metastasis in immune infiltration-related analyses. TAGLN2 can be used as a single indicator to explain the survival probability of patients with ccRCC. In vitro TAGLN2 silencing inhibited the malignant properties of ccRCC by blocking the PI3K/AKT signaling pathway. In addition, TAGLN2 contributes to tumor immune escape and may be a potential therapeutic target for ccRCC.
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Guo CL. Self-Sustained Regulation or Self-Perpetuating Dysregulation: ROS-dependent HIF-YAP-Notch Signaling as a Double-Edged Sword on Stem Cell Physiology and Tumorigenesis. Front Cell Dev Biol 2022; 10:862791. [PMID: 35774228 PMCID: PMC9237464 DOI: 10.3389/fcell.2022.862791] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/29/2022] [Indexed: 12/19/2022] Open
Abstract
Organ development, homeostasis, and repair often rely on bidirectional, self-organized cell-niche interactions, through which cells select cell fate, such as stem cell self-renewal and differentiation. The niche contains multiplexed chemical and mechanical factors. How cells interpret niche structural information such as the 3D topology of organs and integrate with multiplexed mechano-chemical signals is an open and active research field. Among all the niche factors, reactive oxygen species (ROS) have recently gained growing interest. Once considered harmful, ROS are now recognized as an important niche factor in the regulation of tissue mechanics and topology through, for example, the HIF-YAP-Notch signaling pathways. These pathways are not only involved in the regulation of stem cell physiology but also associated with inflammation, neurological disorder, aging, tumorigenesis, and the regulation of the immune checkpoint molecule PD-L1. Positive feedback circuits have been identified in the interplay of ROS and HIF-YAP-Notch signaling, leading to the possibility that under aberrant conditions, self-organized, ROS-dependent physiological regulations can be switched to self-perpetuating dysregulation, making ROS a double-edged sword at the interface of stem cell physiology and tumorigenesis. In this review, we discuss the recent findings on how ROS and tissue mechanics affect YAP-HIF-Notch-PD-L1 signaling, hoping that the knowledge can be used to design strategies for stem cell-based and ROS-targeting therapy and tissue engineering.
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Regulation of Rac1 Activation in Choroidal Endothelial Cells: Insights into Mechanisms in Age-Related Macular Degeneration. Cells 2021; 10:cells10092414. [PMID: 34572063 PMCID: PMC8469925 DOI: 10.3390/cells10092414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/11/2022] Open
Abstract
Age-related macular degeneration (AMD) is one of the leading causes of blindness worldwide. Vision loss from the neovascular form is associated with the invasion of choroidal endothelial cells into the neural retina to form vision-threatening macular neovascularization (MNV). Anti-angiogenic agents are the current standard of care but are effective in only ~50% of AMD cases. The molecular mechanisms involved in invasive MNV point to the importance of regulating signaling pathways that lead to pathologic biologic outcomes. In studies testing the effects of AMD-related stresses, activation of the Rho GTPase, Rac1, was found to be important for the choroidal endothelial cell invasion into the neural retina. However, current approaches to prevent Rac1 activation are inefficient and less effective. We summarize active Rac1-mediated mechanisms that regulate choroidal endothelial cell migration. Specifically, we discuss our work regarding the role of a multidomain protein, IQ motif containing GTPase activating protein 1 (IQGAP1), in sustaining pathologic Rac1 activation and a mechanism by which active Rap1, a Ras-like GTPase, may prevent active Rac1-mediated choroidal endothelial cell migration.
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7
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Fréchette L, Degrandmaison J, Binda C, Boisvert M, Côté L, Michaud T, Lalumière MP, Gendron L, Parent JL. Identification of the interactome of the DP1 receptor for Prostaglandin D 2: Regulation of DP1 receptor signaling and trafficking by IQGAP1. Biochim Biophys Acta Gen Subj 2021; 1865:129969. [PMID: 34352343 DOI: 10.1016/j.bbagen.2021.129969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 07/19/2021] [Accepted: 07/25/2021] [Indexed: 01/16/2023]
Abstract
BACKGROUND Mechanisms governing localization, trafficking and signaling of G protein-coupled receptors (GPCRs) are critical in cell function. Protein-protein interactions are determinant in these processes. However, there are very little interacting proteins known to date for the DP1 receptor for prostaglandin D2. METHODS We performed LC-MS/MS analyses of the DP1 receptor interactome in HEK293 cells. To functionally validate our LC-MS/MS data, we studied the implications of the interaction with the IQGAP1 scaffold protein in the trafficking and signaling of DP1. RESULTS In addition to expected interacting proteins such as heterotrimeric G protein subunits, we identified proteins involved in signaling, trafficking, and folding localized in various cell compartments. Endogenous DP1-IQGAP1 co-immunoprecipitation was observed in colon cancer HT-29 cells. The interaction was augmented by DP1 agonist activation in HEK293 cells and GST-pulldown assays showed that IQGAP1 binds to intracellular loops 2 and 3 of DP1. Co-localization of the two proteins was observed by confocal microscopy at the cell periphery and in intracellular vesicles in the basal state. PGD2 treatment resulted in the redistribution of the DP1-IQGAP1 co-localization in the perinuclear vicinity. DP1 receptor internalization was promoted by overexpression of IQGAP1, while it was diminished by IQGAP1 knockdown with DsiRNAs. DP1-mediated ERK1/2 activation was augmented and sustained overtime by overexpression of IQGAP1 when compared to DP1 expressed alone. IQGAP1 knockdown decreased ERK1/2 activation by DP1 stimulation. Interestingly, ERK1/2 signaling by DP1 was increased when IQGAP2 was silenced, while it was impaired by IQGAP3 knockdown. CONCLUSIONS Our findings define the putative DP1 interactome, a patho-physiologically important receptor, and validated the interaction with IQGAP1 in DP1 function. Our data also reveal that IQGAP proteins may differentially regulate GPCR signaling. GENERAL SIGNIFICANCE The identified putative DP1-interacting proteins open multiple lines of research in DP1 and GPCR biology in various cell compartments.
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Affiliation(s)
- Louis Fréchette
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Jade Degrandmaison
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Chantal Binda
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Marilou Boisvert
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Laurie Côté
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Thomas Michaud
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Marie-Pier Lalumière
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Département d'Anesthésiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Jean-Luc Parent
- Département de Médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada; Centre de recherche du Centre Hospitalier de l'Université de Sherbrooke, Sherbrooke, Québec, Canada.
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Ballinas-Verdugo MA, Jiménez-Ortega RF, Martínez-Martínez E, Rivas N, Contreras-López EA, Carbó R, Sánchez F, Bojalil R, Márquez-Velasco R, Sánchez-Muñoz F, Alejandre-Aguilar R. Circulating miR-146a as a possible candidate biomarker in the indeterminate phase of Chagas disease. Biol Res 2021; 54:21. [PMID: 34289913 PMCID: PMC8293491 DOI: 10.1186/s40659-021-00345-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 07/11/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Chagas disease is considered important and presents intense inflammatory and fibrotic processes induced by the perpetuation of the parasite in the affected tissues and organs. Therefore, it is necessary to inquire about the host defense and attack mechanisms to have a more detailed knowledge about Chagas disease. MicroRNAs are found in blood, tissues and extracellular vesicles. These small regulators of gene expression are involved in physiological and pathological processes in both mammals and parasites. Several microRNAs have deregulated expression in chagasic heart disease, although little is known about their extracellular expression. Our main objective was to evaluate the involvement of miR-21, miR-146a and miR-155 in several samples from mice infected with the TcI Ninoa strain from the acute and indeterminate phases. We also explored a potential functional association of the selected microRNAs using STRING software. This software identified 23 pathways associated with Trypanosoma cruzi infection. In addition, eleven genes were identified through bioinformatics analysis, and we found that SMAD family member 5 was downregulated in both phases. This gene serves as a mediator in the TGF-β signaling pathway. Thus, forty female mice of the CD1 strain were distributed into 4 groups and the expression levels of miR-21, miR-146a and miR-155 were measured in samples of heart tissue, total plasma and plasma extracellular vesicles by quantitative real-time polymerase chain reaction. RESULTS Overexpression of miR-21, miR-146a and miR-155 was observed in heart and plasma in both phases. Moreover, in extracellular vesicles miR-21 and miR-146a were also overexpressed in the acute phase, whereas in the indeterminate chronic phase we found only miR-146a up-regulated. CONCLUSIONS The expression of inflammatory microRNAs miR-21, miR-146a and miR-155 were up-regulated in each of the samples from acutely and chronically infected mice. The relevant finding was that miR-146a was up-regulated in each sample in both phases; therefore, this miRNA could be a possible candidate biomarker in Chagas disease.
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Affiliation(s)
- Martha Alicia Ballinas-Verdugo
- Departamento de Inmunología, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, CDMX, Mexico. .,Departamento de Parasitología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, CDMX, Mexico.
| | - Rogelio Frank Jiménez-Ortega
- Licenciatura en Nutrición, Plantel Texcoco, Universidad Privada del Estado de México, Texcoco, Estado de México, Mexico
| | | | - Nancy Rivas
- Departamento de Parasitología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, CDMX, Mexico
| | | | - Roxana Carbó
- Departamento de Biomedicina Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, CDMX, Mexico
| | - Fausto Sánchez
- División de Ciencias Biológicas y de La Salud, Universidad Autónoma Metropolitana Xochimilco, Mexico City, CDMX, México
| | - Rafael Bojalil
- División de Ciencias Biológicas y de La Salud, Universidad Autónoma Metropolitana Xochimilco, Mexico City, CDMX, México
| | - Ricardo Márquez-Velasco
- Departamento de Inmunología, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, CDMX, Mexico
| | - Fausto Sánchez-Muñoz
- Departamento de Inmunología, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, CDMX, Mexico.,Sección de Postgraduados, Instituto Politécnico Nacional, Escuela Superior de Medicina, Mexico City, CDMX, Mexico
| | - Ricardo Alejandre-Aguilar
- Departamento de Parasitología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, CDMX, Mexico.
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9
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Ramshekar A, Wang H, Kunz E, Pappas C, Hageman GS, Chaqour B, Sacks DB, Hartnett ME. Active Rap1-mediated inhibition of choroidal neovascularization requires interactions with IQGAP1 in choroidal endothelial cells. FASEB J 2021; 35:e21642. [PMID: 34166557 PMCID: PMC8238370 DOI: 10.1096/fj.202100112r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/08/2021] [Accepted: 04/19/2021] [Indexed: 01/13/2023]
Abstract
Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness. The pathophysiology involves activation of choroidal endothelial cells (CECs) to transmigrate the retinal pigment epithelial (RPE) monolayer and form choroidal neovascularization (CNV) in the neural retina. The multidomain GTPase binding protein, IQGAP1, binds active Rac1 and sustains activation of CECs, thereby enabling migration associated with vision-threatening CNV. IQGAP1 also binds the GTPase, Rap1, which when activated reduces Rac1 activation in CECs and CNV. In this study, we tested the hypothesis that active Rap1 binding to IQGAP1 is necessary and sufficient to reduce Rac1 activation in CECs, and CNV. We found that pharmacologic activation of Rap1 or adenoviral transduction of constitutively active Rap1a reduced VEGF-mediated Rac1 activation, migration, and tube formation in CECs. Following pharmacologic activation of Rap1, VEGF-mediated Rac1 activation was reduced in CECs transfected with an IQGAP1 construct that increased active Rap1-IQGAP1 binding but not in CECs transfected with an IQGAP1 construct lacking the Rap1 binding domain. Specific knockout of IQGAP1 in endothelial cells reduced laser-induced CNV and Rac1 activation in CNV lesions, but pharmacologic activation of Rap1 did not further reduce CNV compared to littermate controls. Taken together, our findings provide evidence that active Rap1 binding to the IQ domain of IQGAP1 is sufficient to interfere with active Rac1-mediated CEC activation and CNV formation.
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Affiliation(s)
- Aniket Ramshekar
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA
| | - Haibo Wang
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA
| | - Eric Kunz
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA
| | - Christian Pappas
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA,Steele Center for Translational Medicine, John A. Moran Eye
Center, University of Utah, Salt Lake City, UT, USA
| | - Gregory S. Hageman
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA,Steele Center for Translational Medicine, John A. Moran Eye
Center, University of Utah, Salt Lake City, UT, USA
| | - Brahim Chaqour
- Department of Ophthalmology, Downstate Medical Center,
Brooklyn, NY, USA
| | - David B. Sacks
- Department of Laboratory Medicine, National Institutes of
Health, Bethesda, MD, USA
| | - M. Elizabeth Hartnett
- The John A Moran Eye Center, University of Utah, Salt Lake
City, UT, USA,Correspondence to: M. Elizabeth Hartnett,
MD, Address: 65 Mario Capecchi Drive, Salt Lake City, UT 84132. Tel:
801-213-4110; Fax: 801-581-3357,
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10
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IQGAP1 Is a Scaffold of the Core Proteins of the Hippo Pathway and Negatively Regulates the Pro-Apoptotic Signal Mediated by This Pathway. Cells 2021; 10:cells10020478. [PMID: 33672268 PMCID: PMC7926663 DOI: 10.3390/cells10020478] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 02/13/2021] [Accepted: 02/20/2021] [Indexed: 12/21/2022] Open
Abstract
The Hippo pathway regulates a complex signalling network which mediates several biological functions including cell proliferation, organ size and apoptosis. Several scaffold proteins regulate the crosstalk of the members of the pathway with other signalling pathways and play an important role in the diverse output controlled by this pathway. In this study we have identified the scaffold protein IQGAP1 as a novel interactor of the core kinases of the Hippo pathway, MST2 and LATS1. Our results indicate that IQGAP1 scaffolds MST2 and LATS1 supresses their kinase activity and YAP1-dependent transcription. Additionally, we show that IQGAP1 is a negative regulator of the non-canonical pro-apoptotic pathway and may enable the crosstalk between this pathway and the ERK and AKT signalling modules. Our data also show that bile acids regulate the IQGAP1-MST2-LATS1 signalling module in hepatocellular carcinoma cells, which could be necessary for the inhibition of MST2-dependent apoptosis and hepatocyte transformation.
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11
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Malarkannan S. Molecular mechanisms of FasL-mediated 'reverse-signaling'. Mol Immunol 2020; 127:31-37. [PMID: 32905906 DOI: 10.1016/j.molimm.2020.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/15/2020] [Accepted: 08/21/2020] [Indexed: 02/07/2023]
Abstract
Effector lymphocytes, including NK and T cells, express FasL. Expression of Fas, the receptor for FasL in tumor cells, renders them susceptible to NK and T cell-mediated killing. The functional relevance of FasL in initiating death signals in tumor cells is well-characterized. However, the cytoplasmic interacting partners and the potential signaling pathways downstream of FasL are far from fully defined. FasL possesses an 81 amino acid long cytoplasmic tail with multiple unique recruitment motifs. We predict multiple interdependent signaling complexes form the core of the 'reverse signaling' downstream of FasL. A direct interaction between the proline-rich domain of FasL and the SH3 domain of PI(3)K-p85α initiates the first pathway. This cascade helps FasL to link to PLC-γ2 via PIP3 or the Akt-dependent activation of mTOR complexes. Independently, a GRB2/GADs-binding PXXP cytoplasmic motif of FasL can initiate a Ras-GTP-dependent PAK1→C-Raf→MEK1/2→ERK1/2 activation. FasL can recruit Fyn via the proline-rich domain leading to the recruitment of ADAP. Through its ability to directly interact with Carma1 and TAK1, ADAP initiates the formation of the Carma1/Bcl10/Malt1-based CBM signalosome that is primarily responsible for inflammatory cytokine production. Here, we explore the conserved cytoplasmic domains of FasL, the potential signaling molecules that interact, and the functional downstream consequences within the effector lymphocytes to define the FasL-mediated 'reverse signaling'.
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Affiliation(s)
- Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.
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12
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Sullivan DP, Dalal PJ, Jaulin F, Sacks DB, Kreitzer G, Muller WA. Endothelial IQGAP1 regulates leukocyte transmigration by directing the LBRC to the site of diapedesis. J Exp Med 2019; 216:2582-2601. [PMID: 31395618 PMCID: PMC6829592 DOI: 10.1084/jem.20190008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/10/2019] [Accepted: 07/03/2019] [Indexed: 01/09/2023] Open
Abstract
The function of endothelial cell IQGAP1 during diapedesis requires its actin-binding domain and IQ motifs to recruit the lateral border recycling compartment. Genetic ablation of endothelial cell IQGAP1 expression in vivo causes significant disruption of diapedesis in two models of inflammation. Transendothelial migration (TEM) of leukocytes across the endothelium is critical for inflammation. In the endothelium, TEM requires the coordination of membrane movements and cytoskeletal interactions, including, prominently, recruitment of the lateral border recycling compartment (LBRC). The scaffold protein IQGAP1 was recently identified in a screen for LBRC-interacting proteins. Knockdown of endothelial IQGAP1 disrupted the directed movement of the LBRC and substantially reduced leukocyte TEM. Expression of truncated IQGAP1 constructs demonstrated that the calponin homology domain is required for IQGAP1 localization to endothelial borders and that the IQ domain, on the same IQGAP1 polypeptide, is required for its function in TEM. This is the first reported function of IQGAP1 requiring two domains to be present on the same polypeptide. Additionally, we show for the first time that IQGAP1 in the endothelium is required for efficient TEM in vivo. These findings reveal a novel function for IQGAP1 and demonstrate that IQGAP1 in endothelial cells facilitates TEM by directing the LBRC to the site of TEM.
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Affiliation(s)
- David P Sullivan
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - Prarthana J Dalal
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | | | - David B Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD
| | - Geri Kreitzer
- Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, The City College of New York, New York, NY
| | - William A Muller
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL
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13
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IQGAP1 mediates podocyte injury in diabetic kidney disease by regulating nephrin endocytosis. Cell Signal 2019; 59:13-23. [DOI: 10.1016/j.cellsig.2019.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
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14
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Rotoli D, Morales M, Maeso MDC, Ávila J, Pérez-Rodríguez ND, Mobasheri A, van Noorden CJF, Martín-Vasallo P. IQGAP1, AmotL2, and FKBP51 Scaffoldins in the Glioblastoma Microenvironment. J Histochem Cytochem 2019; 67:481-494. [PMID: 30794467 DOI: 10.1369/0022155419833334] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Glioblastoma (GB) is the most frequently occurring and aggressive primary brain tumor. Glioma stem cells (GSCs) and astrocytoma cells are the predominant malignant cells occurring in GB besides a highly heterogeneous population of migrating, neovascularizing and infiltrating myeloid cells that forms a complex tumor microenvironment (TME). Cross talk between the TME cells is pivotal in the biology of this tumor and, consequently, adaptor proteins at critical junctions of signaling pathways may be crucial. Scaffold proteins (scaffolins or scaffoldins) integrate external and internal stimuli to regulate various signaling pathways, interacting simultaneously with multiple proteins involved. We investigated by double and triple immunofluorescence the localization of IQGAP1, AmotL2, and FKBP51, three closely related scaffoldins, in malignant cells and TME of human GB tumors. We found that IQGAP1 is preferentially expressed in astrocytoma cells, AmotL2 in GSCs, and FKBP51 in white blood cells in human GB tumors. As GSCs are specially the target for novel therapies, we will investigate in further studies whether AmotL2 inhibition is effective in the treatment of GB.
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Affiliation(s)
- Deborah Rotoli
- UD of Biochemistry and Molecular Biology.,Instituto de Tecnologías Biomédicas de Canarias.,Universidad de La Laguna, San Cristóbal de La Laguna, Spain.,Istituto per l'Endocrinologia e l'Oncologia Sperimentale Gaetano Salvatore, Naples, Italy.,Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz, Spain
| | - Manuel Morales
- Oncología Médica.,Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz, Spain.,Oncología Médica, Hospiten Rambla, Santa Cruz, Spain
| | - María-Del-C Maeso
- Servicio de Anatomía Patológica.,Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz, Spain
| | - Julio Ávila
- UD of Biochemistry and Molecular Biology.,Instituto de Tecnologías Biomédicas de Canarias.,Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | | | - Ali Mobasheri
- Department of Regenerative Medicine, State Research Institute Center for Innovative Medicine, Vilnius, Lithuania
| | - Cornelis J F van Noorden
- Department of Medical Biology, Cancer Center Amsterdam, Amsterdam UMC, Amsterdam, The Netherlands.,Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Pablo Martín-Vasallo
- UD of Biochemistry and Molecular Biology.,Instituto de Tecnologías Biomédicas de Canarias.,Universidad de La Laguna, San Cristóbal de La Laguna, Spain
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15
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Abel AM, Tiwari AA, Gerbec ZJ, Siebert JR, Yang C, Schloemer NJ, Dixon KJ, Thakar MS, Malarkannan S. IQ Domain-Containing GTPase-Activating Protein 1 Regulates Cytoskeletal Reorganization and Facilitates NKG2D-Mediated Mechanistic Target of Rapamycin Complex 1 Activation and Cytokine Gene Translation in Natural Killer Cells. Front Immunol 2018; 9:1168. [PMID: 29892299 PMCID: PMC5985319 DOI: 10.3389/fimmu.2018.01168] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 05/09/2018] [Indexed: 12/25/2022] Open
Abstract
Natural killer (NK) cells are innate lymphocytes that play essential roles in mediating antitumor immunity. NK cells respond to various inflammatory stimuli including cytokines and stress-induced cellular ligands which activate germline-encoded activation receptors (NKRs), such as NKG2D. The signaling molecules activated downstream of NKRs are well defined; however, the mechanisms that regulate these pathways are not fully understood. IQ domain-containing GTPase-activating protein 1 (IQGAP1) is a ubiquitously expressed scaffold protein. It regulates diverse cellular signaling programs in various physiological contexts, including immune cell activation and function. Therefore, we sought to investigate the role of IQGAP1 in NK cells. Development and maturation of NK cells from mice lacking IQGAP1 (Iqgap1-/- ) were mostly intact; however, the absolute number of splenic NK cells was significantly reduced. Phenotypic and functional characterization revealed a significant reduction in the egression of NK cells from the bone marrow of Iqagp1-/- mice altering their peripheral homeostasis. Lack of IQGAP1 resulted in reduced NK cell motility and their ability to mediate antitumor immunity in vivo. Activation of Iqgap1-/- NK cells via NKRs, including NKG2D, resulted in significantly reduced levels of inflammatory cytokines compared with wild-type (WT). This reduction in Iqgap1-/- NK cells is neither due to an impaired membrane proximal signaling nor a defect in gene transcription. The levels of Ifng transcripts were comparable between WT and Iqgap1-/- , suggesting that IQGAP1-dependent regulation of cytokine production is regulated by a post-transcriptional mechanism. To this end, Iqgap1-/- NK cells failed to fully induce S6 phosphorylation and showed significantly reduced protein translation following NKG2D-mediated activation, revealing a previously undefined regulatory function of IQGAP1 via the mechanistic target of rapamycin complex 1. Together, these results implicate IQGAP1 as an essential scaffold for NK cell homeostasis and function and provide novel mechanistic insights to the post-transcriptional regulation of inflammatory cytokine production.
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Affiliation(s)
- Alex M Abel
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Aradhana A Tiwari
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Zachary J Gerbec
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Jason R Siebert
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Chao Yang
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Nathan J Schloemer
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States.,Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Kate J Dixon
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States
| | - Monica S Thakar
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States.,Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Subramaniam Malarkannan
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.,Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Milwaukee, WI, United States.,Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
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16
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Zeng F, Jiang W, Zhao W, Fan Y, Zhu Y, Zhang H. Ras GTPase-Activating-Like Protein IQGAP1 (IQGAP1) Promotes Breast Cancer Proliferation and Invasion and Correlates with Poor Clinical Outcomes. Med Sci Monit 2018; 24:3315-3323. [PMID: 29779034 PMCID: PMC5991136 DOI: 10.12659/msm.909916] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Breast cancer is one of the most common female cancers in the world. As a key integrator of cell signaling pathways, IQGAP1 contributes to the development and progression of several cancers. However, the exact effects and molecular mechanisms of IQGAP1 in breast cancer progression remain poorly understood. MATERIAL AND METHODS In the present study, IQGAP1 expression was measured in 96 paired breast cancer samples and the corresponding adjacent non-cancerous tissues by immunohistochemistry and quantitative polymerase chain reaction. To further explore the biological function of IQGAP1 in breast cancer cells, we knocked down IQGAP1 expression in MCF-7 cells and overexpressed it in SK-BR-3 cells. RESULTS IQGAP1 was specifically upregulated in breast cancer tissues compared with the corresponding adjacent non-cancerous tissues. Moreover, IQGAP1 expression was positively correlated with breast cancer survival rate. IQGAP1 also promoted breast cancer cell proliferation and cell cycle progression and suppressed apoptosis. CONCLUSIONS In conclusion, our results suggest that IQGAP1 plays an important role in the cell proliferation and invasion of human breast cancer cells, thus indicating that IQGAP1 may be a potential therapeutic target for the treatment of human breast cancer.
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Affiliation(s)
- Fanye Zeng
- Second Department of Oncology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
| | - Weihua Jiang
- Second Department of Breast Surgery, The Oncological Hospital Affiliated to Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
| | - Wei Zhao
- Department of Clinical Biochemistry, School of Laboratory Medicine, Chengdu Medical College, Chengdu, Sichuan, China (mainland)
| | - Yuxiang Fan
- Second Department of Oncology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
| | - Yanhua Zhu
- Second Department of Oncology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
| | - Hongliang Zhang
- Second Department of Oncology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
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17
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Nbeal2 interacts with Dock7, Sec16a, and Vac14. Blood 2017; 131:1000-1011. [PMID: 29187380 DOI: 10.1182/blood-2017-08-800359] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/21/2017] [Indexed: 12/11/2022] Open
Abstract
Mutations in NBEAL2, the gene encoding the scaffolding protein Nbeal2, are causal of gray platelet syndrome (GPS), a rare recessive bleeding disorder characterized by platelets lacking α-granules and progressive marrow fibrosis. We present here the interactome of Nbeal2 with additional validation by reverse immunoprecipitation of Dock7, Sec16a, and Vac14 as interactors of Nbeal2. We show that GPS-causing mutations in its BEACH domain have profound and possible effects on the interaction with Dock7 and Vac14, respectively. Proximity ligation assays show that these 2 proteins are physically proximal to Nbeal2 in human megakaryocytes. In addition, we demonstrate that Nbeal2 is primarily localized in the cytoplasm and Dock7 on the membrane of or in α-granules. Interestingly, platelets from GPS cases and Nbeal2-/- mice are almost devoid of Dock7, resulting in a profound dysregulation of its signaling pathway, leading to defective actin polymerization, platelet activation, and shape change. This study shows for the first time proteins interacting with Nbeal2 and points to the dysregulation of the canonical signaling pathway of Dock7 as a possible cause of the aberrant formation of platelets in GPS cases and Nbeal2-deficient mice.
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18
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Cardama GA, Gonzalez N, Maggio J, Menna PL, Gomez DE. Rho GTPases as therapeutic targets in cancer (Review). Int J Oncol 2017; 51:1025-1034. [PMID: 28848995 PMCID: PMC5592879 DOI: 10.3892/ijo.2017.4093] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/17/2017] [Indexed: 12/20/2022] Open
Abstract
Rho GTPases are key molecular switches controlling the transduction of external signals to cytoplasmic and nuclear effectors. In the last few years, the development of genetic and pharmacological tools has allowed a more precise definition of the specific roles of Rho GTPases in cancer. The aim of the present review is to describe the cellular functions regulated by these proteins with focus in deregulated signals present in malignant tumors. Finally, we describe the state of the art in search of different experimental therapeutic strategies with Rho GTPases as molecular targets.
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Affiliation(s)
- G A Cardama
- Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Bernal B1876BXD, Buenos Aires, Argentina
| | - N Gonzalez
- Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Bernal B1876BXD, Buenos Aires, Argentina
| | - J Maggio
- Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Bernal B1876BXD, Buenos Aires, Argentina
| | - P Lorenzano Menna
- Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Bernal B1876BXD, Buenos Aires, Argentina
| | - D E Gomez
- Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Bernal B1876BXD, Buenos Aires, Argentina
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19
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Abstract
The specific and rapid formation of protein complexes, involving IQGAP family proteins, is essential for diverse cellular processes, such as adhesion, polarization, and directional migration. Although CDC42 and RAC1, prominent members of the RHO GTPase family, have been implicated in binding to and activating IQGAP1, the exact nature of this protein-protein recognition process has remained obscure. Here, we propose a mechanistic framework model that is based on a multiple-step binding process, which is a prerequisite for the dynamic functions of IQGAP1 as a scaffolding protein and a critical mechanism in temporal regulation and integration of cellular pathways.
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Affiliation(s)
- Kazem Nouri
- Institute of Biochemistry and Molecular Biology II, Medical faculty of the Heinrich-Heine University, Düsseldorf, Germany
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, United Kingdom
| | - Mohammad R Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical faculty of the Heinrich-Heine University, Düsseldorf, Germany
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20
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Rotoli D, Morales M, Ávila J, Maeso MDC, García MDP, Mobasheri A, Martín-Vasallo P. Commitment of Scaffold Proteins in the Onco-Biology of Human Colorectal Cancer and Liver Metastases after Oxaliplatin-Based Chemotherapy. Int J Mol Sci 2017; 18:ijms18040891. [PMID: 28441737 PMCID: PMC5412470 DOI: 10.3390/ijms18040891] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/15/2017] [Accepted: 04/19/2017] [Indexed: 01/13/2023] Open
Abstract
Scaffold proteins play pivotal roles in the regulation of signaling pathways, integrating external and internal stimuli to various cellular outputs. We report the pattern of cellular and subcellular expression of scaffoldins angiomotin-like 2 (AmotL2), FK506 binding protein 5 (FKBP51) and IQ motif containing GTPase-activating protein 1 (IQGAP1) in colorectal cancer (CRC) and metastases in liver resected after oxaliplatin-based chemotherapy (CT). Positive immunostaining for the three scaffoldins was found in most cells in healthy colon, tumor, healthy liver and metastasized liver. The patterns of expression of AmotL2, FKBP51 and IQGAP1 show the greatest variability in immune system cells and neurons and glia cells and the least in blood vessel cells. The simultaneous subcellular localization in tumor cells and other cell types within the tumor suggest an involvement of these three scaffoldins in cancer biology, including a role in Epithelial Mesenchymal Transition. The display in differential localization and quantitative expression of AmotL2, FKBP51, and IQGAP1 could be used as biomarkers for more accurate tumor staging and as potential targets for anti-cancer therapeutics by blocking or slowing down their interconnecting functions. Tough further research needs to be done in order to improve these assessments.
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Affiliation(s)
- Deborah Rotoli
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, Av. Astrofísico Sánchez s/n., 38206 La Laguna, Spain.
- CNR-National Research Council, Institute of Endocrinology and Experimental Oncology (IEOS), Via Sergio Pansini 5, 80131 Naples, Italy.
| | - Manuel Morales
- Service of Medical Oncology, University Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain.
- Service of Medical Oncology, Hospiten® Hospitals, 38001 Santa Cruz de Tenerife, Spain.
| | - Julio Ávila
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, Av. Astrofísico Sánchez s/n., 38206 La Laguna, Spain.
| | - María Del Carmen Maeso
- Service of Pathology, University Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain.
| | | | - Ali Mobasheri
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, GU2 7XH Guildford, UK.
- Center of Excellence in Genomic Medicine Research (CEGMR), King Fahd Medical Research Center (KFMRC), Faculty of Applied Medical Sciences, King AbdulAziz University, 21589 Jeddah, Saudi Arabia.
| | - Pablo Martín-Vasallo
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, Av. Astrofísico Sánchez s/n., 38206 La Laguna, Spain.
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21
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Bardwell AJ, Lagunes L, Zebarjedi R, Bardwell L. The WW domain of the scaffolding protein IQGAP1 is neither necessary nor sufficient for binding to the MAPKs ERK1 and ERK2. J Biol Chem 2017; 292:8750-8761. [PMID: 28396345 DOI: 10.1074/jbc.m116.767087] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 04/07/2017] [Indexed: 01/09/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) scaffold proteins, such as IQ motif containing GTPase activating protein 1 (IQGAP1), are promising targets for novel therapies against cancer and other diseases. Such approaches require accurate information about which domains on the scaffold protein bind to the kinases in the MAPK cascade. Results from previous studies have suggested that the WW domain of IQGAP1 binds to the cancer-associated MAPKs ERK1 and ERK2, and that this domain might thus offer a new tool to selectively inhibit MAPK activation in cancer cells. The goal of this work was therefore to critically evaluate which IQGAP1 domains bind to ERK1/2. Here, using quantitative in vitro binding assays, we show that the IQ domain of IQGAP1 is both necessary and sufficient for binding to ERK1 and ERK2, as well as to the MAPK kinases MEK1 and MEK2. Furthermore, we show that the WW domain is not required for ERK-IQGAP1 binding, and contributes little or no binding energy to this interaction, challenging previous models of how WW-based peptides might inhibit tumorigenesis. Finally, we show that the ERK2-IQGAP1 interaction does not require ERK2 phosphorylation or catalytic activity and does not involve known docking recruitment sites on ERK2, and we obtain an estimate of the dissociation constant (Kd ) for this interaction of 8 μm These results prompt a re-evaluation of published findings and a refined model of IQGAP scaffolding.
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Affiliation(s)
- A Jane Bardwell
- From the Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, California 92697
| | - Leonila Lagunes
- From the Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, California 92697
| | - Ronak Zebarjedi
- From the Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, California 92697
| | - Lee Bardwell
- From the Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, California 92697
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22
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Diaz-Romero J, Nesic D. S100A1 and S100B: Calcium Sensors at the Cross-Roads of Multiple Chondrogenic Pathways. J Cell Physiol 2017; 232:1979-1987. [DOI: 10.1002/jcp.25720] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 11/30/2016] [Indexed: 01/13/2023]
Affiliation(s)
- José Diaz-Romero
- Osteoarticular Research Group; Department of Clinical Research; University of Bern; Bern Switzerland
| | - Dobrila Nesic
- Osteoarticular Research Group; Department of Clinical Research; University of Bern; Bern Switzerland
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23
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Rotoli D, Pérez-Rodríguez ND, Morales M, Maeso MDC, Ávila J, Mobasheri A, Martín-Vasallo P. IQGAP1 in Podosomes/Invadosomes Is Involved in the Progression of Glioblastoma Multiforme Depending on the Tumor Status. Int J Mol Sci 2017; 18:ijms18010150. [PMID: 28098764 PMCID: PMC5297783 DOI: 10.3390/ijms18010150] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/20/2016] [Accepted: 01/06/2017] [Indexed: 02/07/2023] Open
Abstract
Glioblastoma multiforme (GBM) is the most frequent and aggressive primary brain tumor. GBM is formed by a very heterogeneous astrocyte population, neurons, neovascularization and infiltrating myeloid cells (microglia and monocyte derived macrophages). The IQGAP1 scaffold protein interacts with components of the cytoskeleton, cell adhesion molecules, and several signaling molecules to regulate cell morphology and motility, cell cycle and other cellular functions. IQGAP1 overexpression and delocalization has been observed in several tumors, suggesting a role for this protein in cell proliferation, transformation and invasion. IQGAP1 has been identified as a marker of amplifying cancer cells in GBMs. To determine the involvement of IQGAP1 in the onco-biology of GBM, we performed immunohistochemical confocal microscopic analysis of the IQGAP1 protein in human GBM tissue samples using cell type-specific markers. IQGAP1 immunostaining and subcellular localization was heterogeneous; the protein was located in the plasma membrane and, at variable levels, in nucleus and/or cytosol. Moreover, IQGAP1 positive staining was found in podosome/invadopodia-like structures. IQGAP1⁺ staining was observed in neurons (Map2⁺ cells), in cancer stem cells (CSC; nestin⁺) and in several macrophages (CD31⁺ or Iba1⁺). Our results indicate that the IQGAP1 protein is involved in normal cell physiology as well as oncologic processes.
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Affiliation(s)
- Deborah Rotoli
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, La Laguna, Av. Astrofísico Sánchez s/n, 38206 La Laguna, Tenerife, Spain.
- CNR-National Research Council, Institute of Endocrinology and Experimental Oncology (IEOS), Via Sergio Pansini, 5-80131 Naples, Italy.
| | - Natalia Dolores Pérez-Rodríguez
- Service of Medical Oncology, University Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Canary Islands, Spain.
| | - Manuel Morales
- Service of Medical Oncology, University Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Canary Islands, Spain.
- Medical Oncology, Hospiten® Hospitals, 38001 Santa Cruz de Tenerife, Tenerife, Spain.
| | - María Del Carmen Maeso
- Service of Pathology, University Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Canary Islands, Spain.
| | - Julio Ávila
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, La Laguna, Av. Astrofísico Sánchez s/n, 38206 La Laguna, Tenerife, Spain.
| | - Ali Mobasheri
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
- Center of Excellence in Genomic Medicine Research (CEGMR), King Fahd Medical Research Center (KFMRC), Faculty of Applied Medical Sciences, King AbdulAziz University, Jeddah 21589, Saudi Arabia.
| | - Pablo Martín-Vasallo
- Laboratorio de Biología del Desarrollo, UD de Bioquímica y Biología Molecular and Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna, La Laguna, Av. Astrofísico Sánchez s/n, 38206 La Laguna, Tenerife, Spain.
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24
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Nouri K, Fansa EK, Amin E, Dvorsky R, Gremer L, Willbold D, Schmitt L, Timson DJ, Ahmadian MR. IQGAP1 Interaction with RHO Family Proteins Revisited: KINETIC AND EQUILIBRIUM EVIDENCE FOR MULTIPLE DISTINCT BINDING SITES. J Biol Chem 2016; 291:26364-26376. [PMID: 27815503 PMCID: PMC5159498 DOI: 10.1074/jbc.m116.752121] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/27/2016] [Indexed: 11/16/2022] Open
Abstract
IQ motif-containing GTPase activating protein 1 (IQGAP1) plays a central role in the physical assembly of relevant signaling networks that are responsible for various cellular processes, including cell adhesion, polarity, and transmigration. The RHO family proteins CDC42 and RAC1 have been shown to mainly interact with the GAP-related domain (GRD) of IQGAP1. However, the role of its RASGAP C-terminal (RGCT) and C-terminal domains in the interactions with RHO proteins has remained obscure. Here, we demonstrate that IQGAP1 interactions with RHO proteins underlie a multiple-step binding mechanism: (i) a high affinity, GTP-dependent binding of RGCT to the switch regions of CDC42 or RAC1 and (ii) a very low affinity binding of GRD and a C terminus adjacent to the switch regions. These data were confirmed by phosphomimetic mutation of serine 1443 to glutamate within RGCT, which led to a significant reduction of IQGAP1 affinity for CDC42 and RAC1, clearly disclosing the critical role of RGCT for these interactions. Unlike CDC42, an extremely low affinity was determined for the RAC1-GRD interaction, suggesting that the molecular nature of IQGAP1 interaction with CDC42 partially differs from that of RAC1. Our study provides new insights into the interaction characteristics of IQGAP1 with RHO family proteins and highlights the complementary importance of kinetic and equilibrium analyses. We propose that the ability of IQGAP1 to interact with RHO proteins is based on a multiple-step binding process, which is a prerequisite for the dynamic functions of IQGAP1 as a scaffolding protein and a critical mechanism in temporal regulation and integration of IQGAP1-mediated cellular responses.
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Affiliation(s)
- Kazem Nouri
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Eyad K Fansa
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Ehsan Amin
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Radovan Dvorsky
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Lothar Gremer
- the Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany.,Forschungszentrum Jülich, ICS-6, 52428 Jülich, Germany
| | - Dieter Willbold
- the Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany.,Forschungszentrum Jülich, ICS-6, 52428 Jülich, Germany
| | - Lutz Schmitt
- the Institute of Biochemistry, Heinrich-Heine University, 40225 Düsseldorf, Germany, and
| | - David J Timson
- the School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, United Kingdom
| | - Mohammad R Ahmadian
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty of the Heinrich-Heine University, 40225 Düsseldorf, Germany,
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25
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Kauskot A, Poirault-Chassac S, Adam F, Muczynski V, Aymé G, Casari C, Bordet JC, Soukaseum C, Rothschild C, Proulle V, Pietrzyk-Nivau A, Berrou E, Christophe OD, Rosa JP, Lenting PJ, Bryckaert M, Denis CV, Baruch D. LIM kinase/cofilin dysregulation promotes macrothrombocytopenia in severe von Willebrand disease-type 2B. JCI Insight 2016; 1:e88643. [PMID: 27734030 DOI: 10.1172/jci.insight.88643] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
von Willebrand disease type 2B (VWD-type 2B) is characterized by gain-of-function mutations of von Willebrand factor (vWF) that enhance its binding to platelet glycoprotein Ibα and alter the protein's multimeric structure. Patients with VWD-type 2B display variable extents of bleeding associated with macrothrombocytopenia and sometimes with thrombopathy. Here, we addressed the molecular mechanism underlying the severe macrothrombocytopenia both in a knockin murine model for VWD-type 2B by introducing the p.V1316M mutation in the murine Vwf gene and in a patient bearing this mutation. We provide evidence of a profound defect in megakaryocyte (MK) function since: (a) the extent of proplatelet formation was drastically decreased in 2B MKs, with thick proplatelet extensions and large swellings; and (b) 2B MKs presented actin disorganization that was controlled by upregulation of the RhoA/LIM kinase (LIMK)/cofilin pathway. In vitro and in vivo inhibition of the LIMK/cofilin signaling pathway rescued actin turnover and restored normal proplatelet formation, platelet count, and platelet size. These data indicate, to our knowledge for the first time, that the severe macrothrombocytopenia in VWD-type 2B p.V1316M is due to an MK dysfunction that originates from a constitutive activation of the RhoA/LIMK/cofilin pathway and actin disorganization. This suggests a potentially new function of vWF during platelet formation that involves regulation of actin dynamics.
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Affiliation(s)
- Alexandre Kauskot
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France.,INSERM UMR-S 1140, Univ Paris Descartes, Sorbonne Paris Cité, Paris, France
| | | | - Frédéric Adam
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Vincent Muczynski
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Gabriel Aymé
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Caterina Casari
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Jean-Claude Bordet
- Laboratoire d'Hémostase, Hôpital Edouard Herriot, Lyon, France.,Laboratoire de Recherche sur l'Hémophilie, UCBL1, Faculté de Médecine Lyon-Est, Lyon, France
| | - Christelle Soukaseum
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | | | - Valérie Proulle
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France.,Department of Biological Hematology, CHU Bicêtre, Hôpitaux Universitaires Paris Sud, AP-HP, Paris, France
| | | | - Eliane Berrou
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Olivier D Christophe
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Jean-Philippe Rosa
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Peter J Lenting
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Marijke Bryckaert
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Cécile V Denis
- INSERM UMR-S 1176, Univ Paris-Sud, Université Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
| | - Dominique Baruch
- INSERM UMR-S 1140, Univ Paris Descartes, Sorbonne Paris Cité, Paris, France
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26
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Bamidele AO, Kremer KN, Hirsova P, Clift IC, Gores GJ, Billadeau DD, Hedin KE. IQGAP1 promotes CXCR4 chemokine receptor function and trafficking via EEA-1+ endosomes. J Cell Biol 2016. [PMID: 26195666 PMCID: PMC4508899 DOI: 10.1083/jcb.201411045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
IQGAP1 mediates CXCR4 cell surface expression and signaling by regulating EEA-1+ endosome interactions with microtubules during CXCR4 trafficking and recycling. IQ motif–containing GTPase-activating protein 1 (IQGAP1) is a cytoskeleton-interacting scaffold protein. CXCR4 is a chemokine receptor that binds stromal cell–derived factor-1 (SDF-1; also known as CXCL12). Both IQGAP1 and CXCR4 are overexpressed in cancer cell types, yet it was unclear whether these molecules functionally interact. Here, we show that depleting IQGAP1 in Jurkat T leukemic cells reduced CXCR4 expression, disrupted trafficking of endocytosed CXCR4 via EEA-1+ endosomes, and decreased efficiency of CXCR4 recycling. SDF-1–induced cell migration and activation of extracellular signal-regulated kinases 1 and 2 (ERK) MAPK were strongly inhibited, even when forced overexpression restored CXCR4 levels. Similar results were seen in KMBC and HEK293 cells. Exploring the mechanism, we found that SDF-1 treatment induced IQGAP1 binding to α-tubulin and localization to CXCR4-containing endosomes and that CXCR4-containing EEA-1+ endosomes were abnormally located distal from the microtubule (MT)-organizing center (MTOC) in IQGAP1-deficient cells. Thus, IQGAP1 critically mediates CXCR4 cell surface expression and signaling, evidently by regulating EEA-1+ endosome interactions with MTs during CXCR4 trafficking and recycling. IQGAP1 may similarly promote CXCR4 functions in other cancer cell types.
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Affiliation(s)
- Adebowale O Bamidele
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905 Department of Immunology, Mayo Clinic, Rochester, MN 55905
| | | | - Petra Hirsova
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905
| | - Ian C Clift
- Department of Immunology, Mayo Clinic, Rochester, MN 55905 Neurobiology of Disease Research Program, Mayo Clinic, Rochester, MN 55905
| | - Gregory J Gores
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905
| | - Daniel D Billadeau
- Department of Immunology, Mayo Clinic, Rochester, MN 55905 Division of Oncology Research, Mayo Clinic, Rochester, MN 55905
| | - Karen E Hedin
- Department of Immunology, Mayo Clinic, Rochester, MN 55905
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27
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Nussinov R, Jang H, Tsai CJ. Oligomerization and nanocluster organization render specificity. Biol Rev Camb Philos Soc 2015; 90:587-98. [PMID: 24917483 PMCID: PMC4263682 DOI: 10.1111/brv.12124] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 04/30/2014] [Accepted: 05/14/2014] [Indexed: 12/11/2022]
Abstract
Nanoclusters are anchored to membranes, either within them or in the cytoplasm latched onto the cytoskeleton, whose reorganization can regulate their activity. Nanoclusters have been viewed in terms of cooperativity and activation; here we perceive nanocluster organization from a conformational standpoint. This leads us to suggest that while single molecules encode activity, nanoclusters induce specificity, and that this is their main evolutionary aim. Distinct, isoform-specific nanocluster organization can drive the preferred effector (and ligand) interactions and thereby designate signalling pathways. The absence of detailed structural information across the nanocluster, due to size and dynamics, hinders an in-depth grasp of its mechanistic features; however, available data already capture some of the principles and their functional 'raison d'être'. Collectively, clustering lends stability and reduces the likelihood of proteolytic cleavage; it also increases the effective local concentration and enables efficient cooperative activation. However, clustering does not determine the ability of the single molecule to function. Drugs targeting nanoclusters can attenuate activity by hampering cooperativity; however, this may not perturb activation and signalling, which originate from the molecules themselves, and as such, are likely to endure. What then is the major role of nanoclustering? Assuming that single molecules evolved first, with a subsequent increase in cellular complexity and emergence of highly similar isoform variants, evolution faced the threat of signalling promiscuity. We reason that this potential risk was thwarted by oligomerization and clustering; clustering confers higher specificity, and a concomitant extra layer of cellular control. In our Ras example, signalling will be more accurate as a dimer than as a monomer, where its isomer specificity could be compromised.
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Affiliation(s)
- Ruth Nussinov
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Hyunbum Jang
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
| | - Chung-Jung Tsai
- Cancer and Inflammation Program, National Cancer Institute, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702, USA
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28
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Abel AM, Schuldt KM, Rajasekaran K, Hwang D, Riese MJ, Rao S, Thakar MS, Malarkannan S. IQGAP1: insights into the function of a molecular puppeteer. Mol Immunol 2015; 65:336-49. [PMID: 25733387 DOI: 10.1016/j.molimm.2015.02.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/09/2015] [Accepted: 02/09/2015] [Indexed: 02/06/2023]
Abstract
The intracellular spatiotemporal organization of signaling events is critical for normal cellular function. In response to environmental stimuli, cells utilize highly organized signaling pathways that are subject to multiple layers of regulation. However, the molecular mechanisms that coordinate these complex processes remain an enigma. Scaffolding proteins (scaffolins) have emerged as critical regulators of signaling pathways, many of which have well-described functions in immune cells. IQGAP1, a highly conserved cytoplasmic scaffold protein, is able to curb, compartmentalize, and coordinate multiple signaling pathways in a variety of cell types. IQGAP1 plays a central role in cell-cell interaction, cell adherence, and movement via actin/tubulin-based cytoskeletal reorganization. Evidence also implicates IQGAP1 as an essential regulator of the MAPK and Wnt/β-catenin signaling pathways. Here, we summarize the recent advances on the cellular and molecular biology of IQGAP1. We also describe how this pleiotropic scaffolin acts as a true molecular puppeteer, and highlight the significance of future research regarding the role of IQGAP1 in immune cells.
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Affiliation(s)
- Alex M Abel
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kristina M Schuldt
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Kamalakannan Rajasekaran
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - David Hwang
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Matthew J Riese
- Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sridhar Rao
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Monica S Thakar
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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29
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Nussinov R, Jang H. Dynamic multiprotein assemblies shape the spatial structure of cell signaling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 116:158-64. [PMID: 25046855 PMCID: PMC4250281 DOI: 10.1016/j.pbiomolbio.2014.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/07/2014] [Indexed: 11/25/2022]
Abstract
Cell signaling underlies critical cellular decisions. Coordination, efficiency as well as fail-safe mechanisms are key elements. How the cell ensures that these hallmarks are at play are important questions. Cell signaling is often viewed as taking place through discrete and cross-talking pathways; oftentimes these are modularized to emphasize distinct functions. While simple, convenient and clear, such models largely neglect the spatial structure of cell signaling; they also convey inter-modular (or inter-protein) spatial separation that may not exist. Here our thesis is that cell signaling is shaped by a network of multiprotein assemblies. While pre-organized, the assemblies and network are loose and dynamic. They contain transiently-associated multiprotein complexes which are often mediated by scaffolding proteins. They are also typically anchored in the membrane, and their continuum may span the cell. IQGAP1 scaffolding protein which binds proteins including Raf, calmodulin, Mek, Erk, actin, and tens more, with actin shaping B-cell (and likely other) membrane-anchored nanoclusters and allosterically polymerizing in dynamic cytoskeleton formation, and Raf anchoring in the membrane along with Ras, provides a striking example. The multivalent network of dynamic proteins and lipids, with specific interactions forming and breaking, can be viewed as endowing gel-like properties. Collectively, this reasons that efficient, productive and reliable cell signaling takes place primarily through transient, preorganized and cooperative protein-protein interactions spanning the cell rather than stochastic, diffusion-controlled processes.
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Affiliation(s)
- Ruth Nussinov
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA; Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Hyunbum Jang
- Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
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30
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McQuade LR, Balachandran A, Scott HA, Khaira S, Baker MS, Schmidt U. Proteomics of Huntington's disease-affected human embryonic stem cells reveals an evolving pathology involving mitochondrial dysfunction and metabolic disturbances. J Proteome Res 2014; 13:5648-59. [PMID: 25316320 DOI: 10.1021/pr500649m] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the Huntingtin gene, where excessive (≥ 36) CAG repeats encode for glutamine expansion in the huntingtin protein. Research using mouse models and human pathological material has indicated dysfunctions in a myriad of systems, including mitochondrial and ubiquitin/proteasome complexes, cytoskeletal transport, signaling, and transcriptional regulation. Here, we examined the earliest biochemical and pathways involved in HD pathology. We conducted a proteomics study combined with immunocytochemical analysis of undifferentiated HD-affected and unaffected human embryonic stem cells (hESC). Analysis of 1883 identifications derived from membrane and cytosolic enriched fractions revealed mitochondria as the primary dysfunctional organ in HD-affected pluripotent cells in the absence of significant differences in huntingtin protein. Furthermore, on the basis of analysis of 645 proteins found in neurodifferentiated hESC, we show a shift to transcriptional dysregulation and cytoskeletal abnormalities as the primary pathologies in HD-affected cells differentiating along neural lineages in vitro. We also show this is concomitant with an up-regulation in expression of huntingtin protein in HD-affected cells. This study demonstrates the utility of a model that recapitulates HD pathology and offers insights into disease initiation, etiology, progression, and potential therapeutic intervention.
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Affiliation(s)
- Leon R McQuade
- Australian Proteome Analysis Facility, §Australian School of Advanced Medicine, Macquarie University , Sydney, New South Wales 2109, Australia
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31
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Cole LM, Bluff JE, Carolan VA, Paley MN, Tozer GM, Clench MR. MALDI-MSI and label-free LC-ESI-MS/MS shotgun proteomics to investigate protein induction in a murine fibrosarcoma model following treatment with a vascular disrupting agent. Proteomics 2014; 14:890-903. [DOI: 10.1002/pmic.201300429] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/05/2013] [Accepted: 12/19/2013] [Indexed: 02/01/2023]
Affiliation(s)
- Laura M. Cole
- Biomedical Research Centre; Sheffield Hallam University; Sheffield UK
| | - Joanne E. Bluff
- Tumour Microcirculation Group; Department of Oncology; CR-UK/YCR Sheffield Cancer Research Centre; University of Sheffield; Sheffield UK
| | - Vikki A. Carolan
- Biomedical Research Centre; Sheffield Hallam University; Sheffield UK
| | - Martyn N. Paley
- Department of Cardiovascular Science; University of Sheffield; Sheffield UK
| | - Gillian M. Tozer
- Tumour Microcirculation Group; Department of Oncology; CR-UK/YCR Sheffield Cancer Research Centre; University of Sheffield; Sheffield UK
| | - Malcolm R. Clench
- Biomedical Research Centre; Sheffield Hallam University; Sheffield UK
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32
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Interactome analysis of AMP-activated protein kinase (AMPK)-α1 and -β1 in INS-1 pancreatic beta-cells by affinity purification-mass spectrometry. Sci Rep 2014; 4:4376. [PMID: 24625528 PMCID: PMC3953747 DOI: 10.1038/srep04376] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 02/26/2014] [Indexed: 12/23/2022] Open
Abstract
The heterotrimeric enzyme AMP-activated protein kinase (AMPK) is a major metabolic factor that regulates the homeostasis of cellular energy. In particular, AMPK mediates the insulin resistance that is associated with type 2 diabetes. Generally, cellular processes require tight regulation of protein kinases, which is effected through their formation of complex with other proteins and substrates. Despite their critical function in regulation and pathogenesis, there are limited data on the interaction of protein kinases. To identify proteins that interact with AMPK, we performed large-scale affinity purification (AP)-mass spectrometry (MS) of the AMPK-α1 and -β1 subunits. Through a comprehensive analysis, using a combination of immunoprecipitaion and ion trap mass spectrometry, we identified 381 unique proteins in the AMPKα/β interactomes: 325 partners of AMPK-α1 and 243 for AMPK-β1. Further, we identified 196 novel protein-protein interactions with AMPK-α1 and AMPK-β1. Notably, in our bioinformatics analysis, the novel interaction partners mediated functions that are related to the regulation of actin organization. Specifically, several such proteins were linked to pancreatic beta-cell functions, including glucose-stimulated insulin secretion, beta-cell development, beta-cell differentiation, and cell-cell communication.
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33
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Defective tubulin organization and proplatelet formation in murine megakaryocytes lacking Rac1 and Cdc42. Blood 2013; 122:3178-87. [DOI: 10.1182/blood-2013-03-487942] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Key Points
Rac1 and Cdc42 have redundant functions in platelet biogenesis. Deficiency of Rac1 and Cdc42 results in highly abnormal megakaryocyte morphology associated with severely defective tubulin organization.
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34
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Osman MA, Bloom GS, Tagoe EA. Helicobacter pylori-induced alteration of epithelial cell signaling and polarity: a possible mechanism of gastric carcinoma etiology and disparity. Cytoskeleton (Hoboken) 2013; 70:349-59. [PMID: 23629919 DOI: 10.1002/cm.21114] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 03/04/2013] [Accepted: 04/24/2013] [Indexed: 12/11/2022]
Abstract
Gastric cancer, a disease of disparity associated with Helicobacter pylori (H. pylori) infection, is the world's second leading cause of cancer deaths. The pathogen H. pylori target the epithelial adhesion receptors, E-cadherin, and β1-integrin, to modulate the host cytoskeleton via disruption of the epithelial cell polarity necessary for maintaining the infection, but how this leads to the development of the carcinoma is widely unclear. While Rho family GTPases' signaling to the cytoskeleton and these receptors is required for initiating and maintaining the infection, the responsible effectors, and how they might influence the etiology of the carcinomas are currently unknown. Here we discuss the potential role of the Cdc42-IQGAP1 axis, a negative regulator of the tumor suppressors E-cadherin and β1-integrin, as a potential driver of H. pylori-induced gastric carcinoma and propose avenues for addressing its disparity. Chronic dysfunction of the IQGAP1-signaling pathway, resulting from H. pylori-induced disruption of cell polarity, can explain the pathogenesis of the carcinoma, at least, in subsets of infected population, and thus could provide a potential means for personalized medicine.
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Affiliation(s)
- Mahasin A Osman
- Department of Molecular Pharmacology, Physiology and Biotechnology, Warren Alpert Medical School, Brown University, Providence, RI 02912, USA.
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Osman MA, Sarkar FH, Rodriguez-Boulan E. A molecular rheostat at the interface of cancer and diabetes. Biochim Biophys Acta Rev Cancer 2013; 1836:166-76. [PMID: 23639840 DOI: 10.1016/j.bbcan.2013.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 04/23/2013] [Indexed: 12/17/2022]
Abstract
Epidemiology studies revealed the connection between several types of cancer and type 2 diabetes (T2D) and suggested that T2D is both a symptom and a risk factor of pancreatic cancer. High level of circulating insulin (hyperinsulinemia) in obesity has been implicated in promoting aggressive types of cancers. Insulin resistance, a symptom of T2D, pressures pancreatic β-cells to increase insulin secretion, leading to hyperinsulinemia, which in turn leads to a gradual loss of functional β-cell mass, thus indicating a fine balance and interplay between β-cell function and mass. While the mechanisms of these connections are unclear, the mTORC1-Akt signaling pathway has been implicated in controlling β-cell function and mass, and in mediating the link of cancer and T2D. However, incomplete understating of how the pathway is regulated and how it integrates body metabolism has hindered its efficacy as a clinical target. The IQ motif containing GTPase activating protein 1 (IQGAP1)-Exocyst axis is a growth factor- and nutrient-sensor that couples cell growth and division. Here we discuss how IQGAP1-Exocyst, through differential interactions with Rho-type of small guanosine triphosphatases (GTPases), acts as a rheostat that modulates the mTORC1-Akt and MAPK signals, and integrates β-cell function and mass with insulin signaling, thus providing a molecular mechanism for cancer initiation in diabetes. Delineating this regulatory pathway may have the potential of contributing to optimizing the efficacy and selectivity of future therapies for cancer and diabetes.
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Affiliation(s)
- Mahasin A Osman
- Warren Alpert Medical School, Division of Biology and Medicine, Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA.
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Liu Y, Liang W, Yang Q, Ren Z, Chen X, Zha D, Singhal PC, Ding G. IQGAP1 mediates angiotensin II-induced apoptosis of podocytes via the ERK1/2 MAPK signaling pathway. Am J Nephrol 2013; 38:430-44. [PMID: 24247724 DOI: 10.1159/000355970] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/23/2013] [Indexed: 01/20/2023]
Abstract
BACKGROUND/AIMS The mechanism underlying angiotensin II (AngII)-promoted podocyte apoptosis has not been established. IQ domain GTPase-activating protein 1 (IQGAP1) is a scaffolding protein of the mitogen-activated protein kinases (MAPK) signaling pathway, and plays a significant role in apoptosis. The present study evaluates the role of IQGAP1 in AngII-induced podocyte apoptosis. METHODS We randomly assigned 36 male Wistar rats to a normal saline-infused group, an AngII-infused group, or a normal control group, and measured podocyte apoptosis by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay and transmission electron microscopic analysis. In addition, we exposed differentiated mouse podocytes to AngII and then assessed apoptosis by flow cytometry and Hoechst-33258 staining. Expression of IQGAP1 was measured by Western blotting, real-time PCR and immunofluorescence assay in vivo and in vitro. IQGAP1 siRNA and MAPK pathway inhibitors were further introduced to investigate the role of IQGAP1 and MAPK signaling in the process. Coimmunoprecipitation was used to evaluate the interaction between ERK1/2 and IQGAP1. RESULTS AngII promoted podocyte apoptosis in vivo and in vitro. IQGAP1 had a linear distribution along the capillary loops of glomeruli in vivo, and was in the cellular membrane and cytoplasm of cultured podocytes. AngII stimulated IQGAP1 expression and increased phosphorylation of P38, JNK, and ERK1/2. Knockdown of IQGAP1 with siRNA prevented AngII-induced apoptosis of podocytes and reduced AngII-induced phosphorylation of ERK1/2, but not that of P38, JNK. This was accompanied by a reduced interaction between ERK1/2 and IQGAP1. CONCLUSION IQGAP1 contributes to AngII-induced apoptosis of podocytes by interacting with the ERK1/2 signaling protein.
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Affiliation(s)
- Yipeng Liu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
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Andrews WJ, Bradley CA, Hamilton E, Daly C, Mallon T, Timson DJ. A calcium-dependent interaction between calmodulin and the calponin homology domain of human IQGAP1. Mol Cell Biochem 2012; 371:217-23. [PMID: 22944912 DOI: 10.1007/s11010-012-1438-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/25/2012] [Indexed: 01/01/2023]
Abstract
IQGAPs are cytoskeletal scaffolding proteins which collect information from a variety of signalling pathways and pass it on to the microfilaments and microtubules. There is a well-characterised interaction between IQGAP and calmodulin through a series of IQ-motifs towards the middle of the primary sequence. However, it has been shown previously that the calponin homology domain (CHD), located at the N-terminus of the protein, can also interact weakly with calmodulin. Using a recombinant fragment of human IQGAP1 which encompasses the CHD, we have demonstrated that the CHD undergoes a calcium ion-dependent interaction with calmodulin. The CHD can also displace the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulphonate from calcium-calmodulin, suggesting that the interaction involves non-polar residues on the surface of calmodulin. Molecular modelling identified a possible site on the CHD for calmodulin interaction. The physiological significance of this interaction remains to be discovered.
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Affiliation(s)
- William J Andrews
- School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK
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