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Wu L, Wang F, Moncman CL, Pandey M, Clarke HA, Frazier HN, Young LE, Gentry MS, Cai W, Thibault O, Sun RC, Andres DA. RIT1 regulation of CNS lipids RIT1 deficiency Alters cerebral lipid metabolism and reduces white matter tract oligodendrocytes and conduction velocities. Heliyon 2023; 9:e20384. [PMID: 37780758 PMCID: PMC10539968 DOI: 10.1016/j.heliyon.2023.e20384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 07/21/2023] [Accepted: 09/20/2023] [Indexed: 10/03/2023] Open
Abstract
Oligodendrocytes (OLs) generate lipid-rich myelin membranes that wrap axons to enable efficient transmission of electrical impulses. Using a RIT1 knockout mouse model and in situ high-resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) coupled with MS-based lipidomic analysis to determine the contribution of RIT1 to lipid homeostasis. Here, we report that RIT1 loss is associated with altered lipid levels in the central nervous system (CNS), including myelin-associated lipids within the corpus callosum (CC). Perturbed lipid metabolism was correlated with reduced numbers of OLs, but increased numbers of GFAP+ glia, in the CC, but not in grey matter. This was accompanied by reduced myelin protein expression and axonal conduction deficits. Behavioral analyses revealed significant changes in voluntary locomotor activity and anxiety-like behavior in RIT1KO mice. Together, these data reveal an unexpected role for RIT1 in the regulation of cerebral lipid metabolism, which coincide with altered white matter tract oligodendrocyte levels, reduced axonal conduction velocity, and behavioral abnormalities in the CNS.
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Affiliation(s)
- Lei Wu
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
| | - Fang Wang
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
| | - Carole L. Moncman
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
| | - Mritunjay Pandey
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
| | - Harrison A. Clarke
- Department of Neuroscience, College of Medicine, University of Kentucky, KY 40536, USA
| | - Hilaree N. Frazier
- Department of Pharmacological and Nutritional Sciences, College of Medicine, University of Kentucky, KY 40536, USA
| | - Lyndsay E.A. Young
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
- Markey Cancer Center, Lexington, KY 40536, USA
| | - Matthew S. Gentry
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
- Markey Cancer Center, Lexington, KY 40536, USA
- Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL 32611, USA
- Center for Advanced Spatial Biomolecule Research, University of Florida, College of Medicine, Gainesville, FL 32611, USA
| | - Weikang Cai
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, NY 11568, USA
| | - Olivier Thibault
- Department of Pharmacological and Nutritional Sciences, College of Medicine, University of Kentucky, KY 40536, USA
| | - Ramon C. Sun
- Department of Neuroscience, College of Medicine, University of Kentucky, KY 40536, USA
- Markey Cancer Center, Lexington, KY 40536, USA
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
- Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL 32611, USA
- Center for Advanced Spatial Biomolecule Research, University of Florida, College of Medicine, Gainesville, FL 32611, USA
| | - Douglas A. Andres
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY 40536, USA
- Markey Cancer Center, Lexington, KY 40536, USA
- Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, KY 40536, USA
- Gill Heart and Vascular Institute, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
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Kuhn MK, Fleeman RM, Beidler LM, Snyder AM, Chan DC, Proctor EA. Amyloid-β Pathology-Specific Cytokine Secretion Suppresses Neuronal Mitochondrial Metabolism. Cell Mol Bioeng 2023; 16:405-421. [PMID: 37811007 PMCID: PMC10550897 DOI: 10.1007/s12195-023-00782-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 08/28/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction Neuroinflammation and metabolic dysfunction are early alterations in Alzheimer's disease (AD) brain that are thought to contribute to disease onset and progression. Glial activation due to protein deposition results in cytokine secretion and shifts in brain metabolism, which have been observed in AD patients. However, the mechanism by which this immunometabolic feedback loop can injure neurons and cause neurodegeneration remains unclear. Methods We used Luminex XMAP technology to quantify hippocampal cytokine concentrations in the 5xFAD mouse model of AD at milestone timepoints in disease development. We used partial least squares regression to build cytokine signatures predictive of disease progression, as compared to healthy aging in wild-type littermates. We applied the disease-defining cytokine signature to wild-type primary neuron cultures and measured downstream changes in gene expression using the NanoString nCounter system and mitochondrial function using the Seahorse Extracellular Flux live-cell analyzer. Results We identified a pattern of up-regulated IFNγ, IP-10/CXCL10, and IL-9 as predictive of advanced disease. When healthy neurons were exposed to these cytokines in proportions found in diseased brain, gene expression of mitochondrial electron transport chain complexes, including ATP synthase, was suppressed. In live cells, basal and maximal mitochondrial respiration were impaired following cytokine stimulation. Conclusions We identify a pattern of cytokine secretion predictive of progressing amyloid-β pathology in the 5xFAD mouse model of AD that reduces expression of mitochondrial electron transport complexes and impairs mitochondrial respiration in healthy neurons. We establish a mechanistic link between disease-specific immune cues and impaired neuronal metabolism, potentially causing neuronal vulnerability and susceptibility to degeneration in AD. Supplementary Information The online version contains supplementary material available at 10.1007/s12195-023-00782-y.
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Affiliation(s)
- Madison K. Kuhn
- Department of Neurosurgery, Penn State College of Medicine, Hershey, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA USA
| | - Rebecca M. Fleeman
- Department of Neurosurgery, Penn State College of Medicine, Hershey, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA USA
| | - Lynne M. Beidler
- Department of Microbiology & Immunology, Penn State College of Medicine, Hershey, PA USA
| | - Amanda M. Snyder
- Department of Neurology, Penn State College of Medicine, Hershey, PA USA
| | - Dennis C. Chan
- Department of Neurosurgery, Penn State College of Medicine, Hershey, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA USA
| | - Elizabeth A. Proctor
- Department of Neurosurgery, Penn State College of Medicine, Hershey, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA USA
- Department of Engineering Science & Mechanics, Pennsylvania State University, University Park, PA USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA USA
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3
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Kuhn MK, Fleeman RM, Beidler LM, Snyder AM, Chan DC, Proctor EA. Alzheimer's disease-specific cytokine secretion suppresses neuronal mitochondrial metabolism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.07.536014. [PMID: 37066287 PMCID: PMC10104145 DOI: 10.1101/2023.04.07.536014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Introduction Neuroinflammation and metabolic dysfunction are early alterations in Alzheimer's disease brain that are thought to contribute to disease onset and progression. Glial activation due to protein deposition results in cytokine secretion and shifts in brain metabolism, which have been observed in Alzheimer's disease patients. However, the mechanism by which this immunometabolic feedback loop can injure neurons and cause neurodegeneration remains unclear. Methods We used Luminex XMAP technology to quantify hippocampal cytokine concentrations in the 5xFAD mouse model of Alzheimer's disease at milestone timepoints in disease development. We used partial least squares regression to build cytokine signatures predictive of disease progression, as compared to healthy aging in wild-type littermates. We applied the disease-defining cytokine signature to wild-type primary neuron cultures and measured downstream changes in gene expression using the NanoString nCounter system and mitochondrial function using the Seahorse Extracellular Flux live-cell analyzer. Results We identified a pattern of up-regulated IFNγ, IP-10, and IL-9 as predictive of advanced disease. When healthy neurons were exposed to these cytokines in proportions found in diseased brain, gene expression of mitochondrial electron transport chain complexes, including ATP synthase, was suppressed. In live cells, basal and maximal mitochondrial respiration were impaired following cytokine stimulation. Conclusions An Alzheimer's disease-specific pattern of cytokine secretion reduces expression of mitochondrial electron transport complexes and impairs mitochondrial respiration in healthy neurons. We establish a mechanistic link between disease-specific immune cues and impaired neuronal metabolism, potentially causing neuronal vulnerability and susceptibility to degeneration in Alzheimer's disease.
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Affiliation(s)
- Madison K. Kuhn
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA, USA
| | - Rebecca M. Fleeman
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA
| | - Lynne M. Beidler
- Department of Microbiology & Immunology, Penn State College of Medicine, Hershey, PA, USA
| | - Amanda M. Snyder
- Department of Neurology, Penn State College of Medicine, Hershey, PA, USA
| | - Dennis C. Chan
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA, USA
| | - Elizabeth A. Proctor
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA
- Department of Engineering Science & Mechanics, Pennsylvania State University, University Park, PA, USA
- Center for Neural Engineering, Pennsylvania State University, University Park, PA, USA
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4
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Li H, Hu M, Huang Z, Wang Y, Xu Y, Deng J, Zhu M, Feng W, Xu X. A single-cell atlas reveals the heterogeneity of meningeal immunity in a mouse model of Methyl CpG binding protein 2 deficiency. Front Immunol 2023; 13:1056447. [PMID: 36703978 PMCID: PMC9871622 DOI: 10.3389/fimmu.2022.1056447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 12/23/2022] [Indexed: 01/11/2023] Open
Abstract
Methyl CpG binding protein 2 (MeCP2) is a DNA methylation reader protein. Mutations in MeCP2 are the major cause of Rett syndrome (RTT). Increasing evidence has shown that dysregulated immunity and chronic subclinical inflammation are linked to MeCP2 deficiency and contribute to RTT development and deterioration. The meninges surrounding the central nervous system (CNS) contain a wide repertoire of immune cells that participate in immune surveillance within the CNS and influence various brain functions; however, the characterization and role of meningeal immunity in CNS with MeCP2 deficiency remain poorly addressed. Here, we used single-cell sequencing to profile Mecp2-deficient meningeal immune cells from the dura mater, which has been reported to contain the most meningeal immune cells during homeostasis. Data showed that the meninges of Mecp2-null mice contained the same diverse immune cell populations as control mice and showed an up-regulation of immune-related processes. B cell populations were greater in Mecp2-null mice than in control mice, and the expression of genes encoding for immunoglobulins was remarkably higher. Mecp2-deficient meninges also contained more cytotoxic CD8+ T cells than control meninges. With increased interferon-γ transcription in T and natural killer cells, meningeal macrophages showed decreased suppression and increased activity in Mecp2-deficienct mice. Together, these findings provide novel insights into meningeal immunity, which is a less studied aspect of neuroimmune interactions in Mecp2-mutated diseases, and offer an essential resource for comparative analyses and data exploration to better understand the functional role of meningeal immunity in RTT.
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Affiliation(s)
- Huiping Li
- Department of Child Health Care, Children’s Hospital of Fudan University, National Children’s Medical Center, Shanghai, China,*Correspondence: Huiping Li, ; Weijun Feng, ; Xiu Xu,
| | - Meixin Hu
- Department of Child Health Care, Children’s Hospital of Fudan University, National Children’s Medical Center, Shanghai, China
| | - Zhuxi Huang
- Institute of Pediatrics, Children’s Hospital of Fudan University, Shanghai, China,Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yi Wang
- Department of Child Health Care, Children’s Hospital of Fudan University, National Children’s Medical Center, Shanghai, China
| | - Ying Xu
- Institute of Pediatrics, Children’s Hospital of Fudan University, Shanghai, China,Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jingxin Deng
- Department of Child Health Care, Children’s Hospital of Fudan University, National Children’s Medical Center, Shanghai, China
| | - Ming Zhu
- Institute of Pediatrics, Children’s Hospital of Fudan University, Shanghai, China,Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Weijun Feng
- Institute of Pediatrics, Children’s Hospital of Fudan University, Shanghai, China,Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China,*Correspondence: Huiping Li, ; Weijun Feng, ; Xiu Xu,
| | - Xiu Xu
- Department of Child Health Care, Children’s Hospital of Fudan University, National Children’s Medical Center, Shanghai, China,*Correspondence: Huiping Li, ; Weijun Feng, ; Xiu Xu,
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5
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Van R, Cuevas-Navarro A, Castel P, McCormick F. The molecular functions of RIT1 and its contribution to human disease. Biochem J 2020; 477:2755-2770. [PMID: 32766847 PMCID: PMC7787054 DOI: 10.1042/bcj20200442] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 12/29/2022]
Abstract
RIT1 is a member of the Ras family of GTPases that direct broad cellular physiological responses through tightly controlled signaling networks. The canonical Ras GTPases are well-defined regulators of the RAF/MEK/ERK pathway and mutations in these are pathogenic in cancer and a class of developmental disorders termed RASopathies. Emerging clinical evidences have now demonstrated a role for RIT1 in RASopathies, namely Noonan syndrome, and various cancers including lung adenocarcinoma and myeloid malignancies. While RIT1 has been mostly described in the context of neuronal differentiation and survival, the mechanisms underlying aberrant RIT1-mediated signaling remain elusive. Here, we will review efforts undertaken to characterize the biochemical and functional properties of the RIT1 GTPase at the molecular, cellular, and organismal level, as well as provide a phenotypic overview of different human conditions caused by RIT1 mutations. Deeper understanding of RIT1 biological function and insight to its pathogenic mechanisms are imperative to developing effective therapeutic interventions for patients with RIT1-mutant Noonan syndrome and cancer.
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Affiliation(s)
- Richard Van
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, U.S.A
| | - Antonio Cuevas-Navarro
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, U.S.A
| | - Pau Castel
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, U.S.A
| | - Frank McCormick
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, U.S.A
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6
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RIT1 suppresses esophageal squamous cell carcinoma growth and metastasis and predicts good prognosis. Cell Death Dis 2018; 9:1085. [PMID: 30348939 PMCID: PMC6197279 DOI: 10.1038/s41419-018-0979-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 06/23/2018] [Accepted: 06/26/2018] [Indexed: 01/05/2023]
Abstract
Ras-like without CAAX1 (RIT1) protein is a member of Ras family, which plays critical roles in signaling pathways and cellular process regulation. However, the role of RIT1 in esophageal squamous cell carcinoma (ESCC) is unclear. In this study, we found that the expression of RIT1 is downregulated in ESCC compared to corresponding non-tumor tissues. The low-level expression of RIT1 was correlated with poorer prognosis. Then we showed that RIT1 inhibited proliferation, invasion, and migration of ESCC cells, and silencing RIT1 by shRNA promoted tumorigenicity and metastasis in nude mice. We further demonstrated that RIT1 inhibited the malignant behaviors of ESCC through inhibiting the PI3K/AKT and MAPK pathway and epithelial–mesenchymal transition in ESCC cells. Our study also revealed that RIT1 increased drug sensitivity to cisplatin (CDDP), and this function could be carried out through downregulating stemness of ESCC. In conclusion, our study indicates for the first time that RIT1 displays tumor-suppressing functions in ESCC, and these functions were carried out by inhibiting MAPK and PI3K/AKT signaling pathway, inhibiting EMT, and downregulating cancer stemness of ESCC cells.
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7
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Meyer zum Büschenfelde U, Brandenstein LI, von Elsner L, Flato K, Holling T, Zenker M, Rosenberger G, Kutsche K. RIT1 controls actin dynamics via complex formation with RAC1/CDC42 and PAK1. PLoS Genet 2018; 14:e1007370. [PMID: 29734338 PMCID: PMC5937737 DOI: 10.1371/journal.pgen.1007370] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 04/18/2018] [Indexed: 12/12/2022] Open
Abstract
RIT1 belongs to the RAS family of small GTPases. Germline and somatic RIT1 mutations have been identified in Noonan syndrome (NS) and cancer, respectively. By using heterologous expression systems and purified recombinant proteins, we identified the p21-activated kinase 1 (PAK1) as novel direct effector of RIT1. We found RIT1 also to directly interact with the RHO GTPases CDC42 and RAC1, both of which are crucial regulators of actin dynamics upstream of PAK1. These interactions are independent of the guanine nucleotide bound to RIT1. Disease-causing RIT1 mutations enhance protein-protein interaction between RIT1 and PAK1, CDC42 or RAC1 and uncouple complex formation from serum and growth factors. We show that the RIT1-PAK1 complex regulates cytoskeletal rearrangements as expression of wild-type RIT1 and its mutant forms resulted in dissolution of stress fibers and reduction of mature paxillin-containing focal adhesions in COS7 cells. This effect was prevented by co-expression of RIT1 with dominant-negative CDC42 or RAC1 and kinase-dead PAK1. By using a transwell migration assay, we show that RIT1 wildtype and the disease-associated variants enhance cell motility. Our work demonstrates a new function for RIT1 in controlling actin dynamics via acting in a signaling module containing PAK1 and RAC1/CDC42, and highlights defects in cell adhesion and migration as possible disease mechanism underlying NS. Noonan syndrome (NS) belongs to the RASopathies, a group of developmental diseases caused by mutations in genes encoding RAS-MAPK pathway components. Germline mutations in RIT1 have been identified in NS. RIT1 belongs to the RAS superfamily, however, the cellular function of RIT1 remains elusive. We show that RIT1 binds p21-activated kinase 1 (PAK1), an effector of the RHO GTPases RAC1 and CDC42, which are important regulators of cytoskeletal dynamics. NS-associated RIT1 mutants enhance complex formation between RIT1, RAC1/CDC42 and PAK1. Expression of wild-type or mutant forms of RIT1 caused loss of stress fibers and mature focal adhesions and enhanced cell motility. Our data suggest that dysfunction in actin dynamics is a novel aspect in the pathophysiology of RASopathies.
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Affiliation(s)
| | | | - Leonie von Elsner
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kristina Flato
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Martin Zenker
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | - Georg Rosenberger
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail: (KK); (GR)
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail: (KK); (GR)
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Ghafelehbashi H, Pahlevan Kakhki M, Kular L, Moghbelinejad S, Ghafelehbashi SH. Decreased Expression of IFNG-AS1
,IFNG
and IL-1B
Inflammatory Genes in Medicated Schizophrenia and Bipolar Patients. Scand J Immunol 2017; 86:479-485. [DOI: 10.1111/sji.12620] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/09/2017] [Indexed: 01/22/2023]
Affiliation(s)
- H. Ghafelehbashi
- Cellular and Molecular Research Center; Qazvin University of Medical Sciences; Qazvin Iran
| | - M. Pahlevan Kakhki
- Department of Genetics; Faculty of Biological Sciences; Tarbiat Modares University; Tehran Iran
| | - L. Kular
- Department of Clinical Neuroscience; Center for Molecular Medicine; Karolinska Institute; Karolinska University Hospital; Stockholm Sweden
| | - S. Moghbelinejad
- Cellular and Molecular Research Center; Qazvin University of Medical Sciences; Qazvin Iran
- Department of Psychiatry; Qazvin University of Medical Sciences; Qazvin Iran
| | - S. H. Ghafelehbashi
- Cellular and Molecular Research Center; Qazvin University of Medical Sciences; Qazvin Iran
- Department of Psychiatry; Qazvin University of Medical Sciences; Qazvin Iran
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9
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Brain interference: Revisiting the role of IFNγ in the central nervous system. Prog Neurobiol 2017; 156:149-163. [DOI: 10.1016/j.pneurobio.2017.05.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 05/15/2017] [Accepted: 05/17/2017] [Indexed: 01/28/2023]
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10
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Jemli A, Eshili A, Trifa F, Mechri A, Zaafrane F, Gaha L, Juckel G, Tensaout BBHJ. Association of the IFN-γ (+874A/T) Genetic Polymorphism with Paranoid Schizophrenia in Tunisian Population. Immunol Invest 2016; 46:159-171. [PMID: 27819519 DOI: 10.1080/08820139.2016.1237523] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Since growing evidence suggests a significant role of chronic low-grade inflammation in the physiopathology of schizophrenia, we have hypothesized that functional genetic variant of the IFN gamma (IFN-γ; +874A/T; rs2430561) gene may be involved in the predisposition to schizophrenia. This research is based on a case-control study which aims to identify whether polymorphism of the IFN-γ gene is a risk factor for the development of schizophrenia. The RFLP-PCR genotyping of the IFN-γ gene was conducted on a Tunisian population composed of 218 patients and 162 controls. The IFN-γ (+874A/T) polymorphism analysis showed higher frequencies of minor homozygous genotype (TT) and allele (T) in all patients compared with controls (11.5 vs. 4.9%; p = 0.03, OR = 2.64 and 30.7 vs. 24.1%, p = 0.04, OR = 1.4, respectively). This correlation was confirmed for male but not for female patients. Also, the T allele was significantly more common among patients with paranoid schizophrenia when compared with controls (25.8 vs. 4.9%, p = 0.0001; OR = 6.7). Using the binary regression analysis to eliminate confounding factors as age and sex, only this last association remained significant (p = 0.03; OR = 1.76, CI = 1.05-2.93). In conclusion, our results showed a significant association between +874A/T polymorphism of IFN-γ and paranoid schizophrenia, suggesting that this single nucleotide polymorphism (SNP) or another at proximity could predispose to paranoid schizophrenia. Since the minor allele of this polymorphism was correlated with an increased expression of their product, our study validates the hypothesis of excessive pro-inflammatory cytokine in the physiopathology of paranoid schizophrenia.
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Affiliation(s)
- Achraf Jemli
- a Laboratory of Genetics, Biodiversity and Bioresource Valorization, Higher Institute of Biotechnology of Monastir , University of Monastir , Monastir , Tunisia
| | - Awatef Eshili
- a Laboratory of Genetics, Biodiversity and Bioresource Valorization, Higher Institute of Biotechnology of Monastir , University of Monastir , Monastir , Tunisia
| | - Fatma Trifa
- b Department of Biostatistics , Higher Institute of Biotechnology of Monastir, University of Monastir , Monastir , Tunisia.,c Laboratory of Biomass Valorization and Production of Eucaryotic Proteins, Center of Biotechnology of Sfax , Sfax , Tunisia
| | - Anouar Mechri
- d Department of Psychiatry and Vulnerability to Psychoses Laboratory - CHU Monastir , University of Monastir , Monastir , Tunisia
| | - Ferid Zaafrane
- d Department of Psychiatry and Vulnerability to Psychoses Laboratory - CHU Monastir , University of Monastir , Monastir , Tunisia
| | - Lotfi Gaha
- d Department of Psychiatry and Vulnerability to Psychoses Laboratory - CHU Monastir , University of Monastir , Monastir , Tunisia
| | - George Juckel
- e Department of Psychiatry and Psychotherapy , Ruhr University, Bochum LWL University Hospital Bochum , Bochum , Germany
| | - Besma Bel Hadj Jrad Tensaout
- a Laboratory of Genetics, Biodiversity and Bioresource Valorization, Higher Institute of Biotechnology of Monastir , University of Monastir , Monastir , Tunisia
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11
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Abstract
The Rit subfamily of GTPases is a founding branch within the Ras family of small G-proteins and preserves unique sequences in the G2 effector loop domain and the C-terminus. Rit proteins regulate a diversity of signal transduction pathways, some of which are similar to and others of which differ from the pathways that are regulated by other Ras family GTPases. Rit proteins have been demonstrated to be essential regulators in neuronal differentiation and survival. Here, we describe the materials and methods utilized to characterize cellular signaling for the Rit subfamily of G-proteins in neuronal differentiation and survival.
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12
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Onore CE, Schwartzer JJ, Careaga M, Berman RF, Ashwood P. Maternal immune activation leads to activated inflammatory macrophages in offspring. Brain Behav Immun 2014; 38:220-6. [PMID: 24566386 PMCID: PMC4321784 DOI: 10.1016/j.bbi.2014.02.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 01/24/2014] [Accepted: 02/10/2014] [Indexed: 02/07/2023] Open
Abstract
Several epidemiological studies have shown an association between infection or inflammation during pregnancy and increased risk of autism in the child. In addition, animal models have illustrated that maternal inflammation during gestation can cause autism-relevant behaviors in the offspring; so called maternal immune activation (MIA) models. More recently, permanent changes in T cell cytokine responses were reported in children with autism and in offspring of MIA mice; however, the cytokine responses of other immune cell populations have not been thoroughly investigated in these MIA models. Similar to changes in T cell function, we hypothesized that following MIA, offspring will have long-term changes in macrophage function. To test this theory, we utilized the poly (I:C) MIA mouse model in C57BL/6J mice and examined macrophage cytokine production in adult offspring. Pregnant dams were given either a single injection of 20mg/kg polyinosinic-polycytidylic acid, poly (I:C), or saline delivered intraperitoneally on gestational day 12.5. When offspring of poly (I:C) treated dams reached 10weeks of age, femurs were collected and bone marrow-derived macrophages were generated. Cytokine production was measured in bone marrow-derived macrophages incubated for 24h in either growth media alone, LPS, IL-4/LPS, or IFN-γ/LPS. Following stimulation with LPS alone, or the combination of IFN-γ/LPS, macrophages from offspring of poly (I:C) treated dams produced higher levels of IL-12(p40) (p<0.04) suggesting an increased M1 polarization. In addition, even without the presence of a polarizing cytokine or LPS stimulus, macrophages from offspring of poly (I:C) treated dams exhibited a higher production of CCL3 (p=0.05). Moreover, CCL3 levels were further increased when stimulated with LPS, or polarized with either IL-4/LPS or IFN-γ/LPS (p<0.05) suggesting a general increase in production of this chemokine. Collectively, these data suggest that MIA can produce lasting changes in macrophage function that are sustained into adulthood.
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Affiliation(s)
- Charity E Onore
- Department of Medical Microbiology and Immunology, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
| | - Jared J Schwartzer
- The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; Department of Psychiatry and Behavioral Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; Department of Psychology and Education, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, United States
| | - Milo Careaga
- Department of Medical Microbiology and Immunology, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
| | - Robert F Berman
- The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; Department of Psychiatry and Behavioral Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; Department of Neurological Surgery, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
| | - Paul Ashwood
- Department of Medical Microbiology and Immunology, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States; The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States.
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13
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Reversible nerve damage and corneal pathology in murine herpes simplex stromal keratitis. J Virol 2014; 88:7870-80. [PMID: 24789786 DOI: 10.1128/jvi.01146-14] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Herpes simplex virus type 1 (HSV-1) shedding from sensory neurons can trigger recurrent bouts of herpes stromal keratitis (HSK), an inflammatory response that leads to progressive corneal scarring and blindness. A mouse model of HSK is often used to delineate immunopathogenic mechanisms and bears many of the characteristics of human disease, but it tends to be more chronic and severe than human HSK. Loss of blink reflex (BR) in human HSK is common and due to a dramatic retraction of corneal sensory nerve termini in the epithelium and the nerve plexus at the epithelial/stromal interface. However, the relationship between loss of BR due to nerve damage and corneal pathology associated with HSK remains largely unexplored. Here, we show a similar retraction of corneal nerves in mice with HSK. Indeed, we show that much of the HSK-associated corneal inflammation in mice is actually attributable to damage to the corneal nerves and accompanying loss of BR and can be prevented or ameliorated by tarsorrhaphy (suturing eyelids closed), a clinical procedure commonly used to prevent corneal exposure and desiccation. In addition, we show that HSK-associated nerve retraction, loss of BR, and severe pathology all are reversible and regulated by CD4(+) T cells. Thus, defining immunopathogenic mechanisms of HSK in the mouse model will necessitate distinguishing mechanisms associated with the immunopathologic response to the virus from those associated with loss of corneal sensation. Based on our findings, investigation of a possible contribution of nerve damage and BR loss to human HSK also appears warranted. Importance: HSK in humans is a potentially blinding disease characterized by recurrent inflammation and progressive scarring triggered by viral release from corneal nerves. Corneal nerve damage is a known component of HSK, but the causes and consequences of HSK-associated nerve damage remain obscure. We show that desiccation of the corneal surface due to nerve damage and associated loss of BR severely exacerbates and prolongs inflammation-induced pathology in mice. Preventing corneal desiccation results in a milder and more transient HSK with variable scarring that mirrors HSK seen in most humans. We further show that nerve damage is reversible and regulated by CD4(+) T cells. Thus, we provide a mouse model that more closely resembles typical human HSK and suggest nerve damage is an important but largely overlooked factor in human disease.
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Cai W, Shi GX, Andres DA. Putting the Rit in cellular resistance: Rit, p38 MAPK and oxidative stress. Commun Integr Biol 2013; 6:e22297. [PMID: 23802035 PMCID: PMC3689566 DOI: 10.4161/cib.22297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells mobilize diverse signaling pathways to protect against stress-mediated injury. Ras family GTPases play critical roles in this process, controlling the activation and integration of multiple regulatory cascades. p38 mitogen-activated protein kinase (MAPK) signaling serves as a critical fulcrum in this process, regulating networks that stimulate cellular apoptosis but also promote cell survival. However, this functional dichotomy is incompletely understood, particularly regulation of p38-dependent survival. Here, we discuss our recent evidence that the Rit GTPase associates with and is required for stress-mediated activation of a scaffolded p38-MK2-HSP27-Akt pro-survival signaling cascade. Drosophila lacking D-Ric, a Rit homologue, are susceptible to a variety of environmental stresses, while embryonic fibroblasts derived from Rit knockout mice display blunted stress-dependent signaling and decreased viability. Conversely, expression of constitutively active Rit triggers p38-Akt-dependent cell survival. Together, our studies establish Rit as the central regulator of an evolutionarily conserved, p38-dependent signaling cascade that functions as a critical survival mechanism in response to stress.
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Affiliation(s)
- Weikang Cai
- Department of Molecular and Cellular Biochemistry; College of Medicine; University of Kentucky; Lexington, KY USA
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15
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Shi GX, Cai W, Andres DA. Rit subfamily small GTPases: regulators in neuronal differentiation and survival. Cell Signal 2013; 25:2060-8. [PMID: 23770287 DOI: 10.1016/j.cellsig.2013.06.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/04/2013] [Indexed: 02/07/2023]
Abstract
Ras family small GTPases serve as binary molecular switches to regulate a broad array of cellular signaling cascades, playing essential roles in a vast range of normal physiological processes, with dysregulation of numerous Ras-superfamily G-protein-dependent regulatory cascades underlying the development of human disease. However, the physiological function for many "orphan" Ras-related GTPases remain poorly characterized, including members of the Rit subfamily GTPases. Rit is the founding member of a novel branch of the Ras subfamily, sharing close homology with the neuronally expressed Rin and Drosophila Ric GTPases. Here, we highlight recent studies using transgenic and knockout animal models which have begun to elucidate the physiological roles for the Rit subfamily, including emerging roles in the regulation of neuronal morphology and cellular survival signaling, and discuss new genetic data implicating Rit and Rin signaling in disorders such as cancer, Parkinson's disease, autism, and schizophrenia.
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Affiliation(s)
- Geng-Xian Shi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, BBSRB, 741S. Limestone St., Lexington, KY 40536-0509, USA
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16
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Goines PE, Ashwood P. Cytokine dysregulation in autism spectrum disorders (ASD): possible role of the environment. Neurotoxicol Teratol 2013; 36:67-81. [PMID: 22918031 PMCID: PMC3554862 DOI: 10.1016/j.ntt.2012.07.006] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/03/2012] [Accepted: 07/31/2012] [Indexed: 02/07/2023]
Abstract
Autism spectrum disorders (ASD) are neurodevelopmental diseases that affect an alarming number of individuals. The etiological basis of ASD is unclear, and evidence suggests it involves both genetic and environmental factors. There are many reports of cytokine imbalances in ASD. These imbalances could have a pathogenic role, or they may be markers of underlying genetic and environmental influences. Cytokines act primarily as mediators of immunological activity but they also have significant interactions with the nervous system. They participate in normal neural development and function, and inappropriate activity can have a variety of neurological implications. It is therefore possible that cytokine dysregulation contributes directly to neural dysfunction in ASD. Further, cytokine profiles change dramatically in the face of infection, disease, and toxic exposures. Imbalances in cytokines may represent an immune response to environmental contributors to ASD. The following review is presented in two main parts. First, we discuss select cytokines implicated in ASD, including IL-1Β, IL-6, IL-4, IFN-γ, and TGF-Β, and focus on their role in the nervous system. Second, we explore several neurotoxic environmental factors that may be involved in the disorders, and focus on their immunological impacts. This review represents an emerging model that recognizes the importance of both genetic and environmental factors in ASD etiology. We propose that the immune system provides critical clues regarding the nature of the gene by environment interactions that underlie ASD pathophysiology.
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Affiliation(s)
- Paula E. Goines
- University of California, Davis, School of Veterinary Medicine, Department of Molecular Biosciences
| | - Paul Ashwood
- University of California, Davis, School of Medicine, Department of Medical Microbiology and Immunology
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17
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Rit GTPase regulates a p38 MAPK-dependent neuronal survival pathway. Neurosci Lett 2012; 531:125-30. [PMID: 23123784 DOI: 10.1016/j.neulet.2012.10.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/12/2012] [Accepted: 10/22/2012] [Indexed: 11/24/2022]
Abstract
Rit, along with Rin and Drosophila Ric, comprises the Rit subfamily of Ras-related small GTPases. Although the cellular functions of many Ras family GTPases are well established, the physiological significance of Rit remains poorly understood. Loss of Rit sensitizes multiple mammalian cell lines and mouse embryonic fibroblasts (MEFs) derived from Rit(-/-) mice to oxidative stress-mediated apoptosis. However, whether Rit-mediated pro-survival signaling extends to other cell types, particularly neurons, is presently unknown. Here, to examine these issues we generated a transgenic mouse overexpressing constitutively active Rit (Rit(Q79L)) exclusively in neurons, under control of the Synapsin I promoter. Active Rit-expressing hippocampal neurons display a dramatic increase in oxidative stress resistance. Moreover, pharmacological inhibitor studies demonstrate that p38 MAPK, rather than a MEK/ERK signaling cascade, is required for Rit-mediated protection. Together, the present studies identify a critical role for the Rit-p38 MAPK signaling cascade in promoting hippocampal neuron survival following oxidative stress.
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18
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Shi GX, Cai W, Andres DA. Rit-mediated stress resistance involves a p38-mitogen- and stress-activated protein kinase 1 (MSK1)-dependent cAMP response element-binding protein (CREB) activation cascade. J Biol Chem 2012; 287:39859-68. [PMID: 23038261 DOI: 10.1074/jbc.m112.384248] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The cAMP response element (CRE)-binding protein (CREB) is a key regulatory factor of gene transcription, and plays an essential role in development of the central nervous system and for neuroprotection. Multiple signaling pathways have been shown to contribute to the regulation of CREB-dependent transcription, including both ERK and p38 mitogen-activated protein (MAP) kinases cascades. Recent studies have identified the Ras-related small G-protein, Rit, as a central regulator of a p38-MK2-HSP27 signaling cascade that functions as a critical survival mechanism for cells adapting to stress. Here, we examine the contribution of Rit-p38 signaling to the control of stress-dependent gene transcription. Using a pheochromocytoma cell model, we find that a novel Rit-p38-MSK1/2 pathway plays a critical role in stress-mediated CREB activation. RNAi-mediated Rit silencing, or inhibition of p38 or MSK1/2 kinases, was found to disrupt stress-mediated CREB-dependent transcription, resulting in increased cell death. Furthermore, ectopic expression of active Rit stimulates CREB-Ser133 phosphorylation, induces expression of the anti-apoptotic Bcl-2 and Bcl(XL) proteins, and promotes cell survival. These data indicate that the Rit-p38-MSK1/2 signaling pathway may have an important role in the stress-dependent regulation of CREB-dependent gene expression.
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Affiliation(s)
- Geng-Xian Shi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0509, USA.
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Shi GX, Andres DA, Cai W. Ras family small GTPase-mediated neuroprotective signaling in stroke. Cent Nerv Syst Agents Med Chem 2012; 11:114-37. [PMID: 21521171 DOI: 10.2174/187152411796011349] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/18/2011] [Accepted: 03/22/2011] [Indexed: 12/31/2022]
Abstract
Selective neuronal cell death is one of the major causes of neuronal damage following stroke, and cerebral cells naturally mobilize diverse survival signaling pathways to protect against ischemia. Importantly, therapeutic strategies designed to improve endogenous anti-apoptotic signaling appear to hold great promise in stroke treatment. While a variety of complex mechanisms have been implicated in the pathogenesis of stroke, the overall mechanisms governing the balance between cell survival and death are not well-defined. Ras family small GTPases are activated following ischemic insults, and in turn, serve as intrinsic switches to regulate neuronal survival and regeneration. Their ability to integrate diverse intracellular signal transduction pathways makes them critical regulators and potential therapeutic targets for neuronal recovery after stroke. This article highlights the contribution of Ras family GTPases to neuroprotective signaling cascades, including mitogen-activated protein kinase (MAPK) family protein kinase- and AKT/PKB-dependent signaling pathways as well as the regulation of cAMP response element binding (CREB), Forkhead box O (FoxO) and hypoxiainducible factor 1(HIF1) transcription factors, in stroke.
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Affiliation(s)
- Geng-Xian Shi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, 741 S. Limestone St., Lexington, KY 40536-0509, USA.
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Cai W, Rudolph JL, Harrison SMW, Jin L, Frantz AL, Harrison DA, Andres DA. An evolutionarily conserved Rit GTPase-p38 MAPK signaling pathway mediates oxidative stress resistance. Mol Biol Cell 2011; 22:3231-41. [PMID: 21737674 PMCID: PMC3164468 DOI: 10.1091/mbc.e11-05-0400] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Rit knockout mice and D-Ric null Drosophila were used to identify the Rit/RIC subfamily of Ras-related GTPases as regulators of an evolutionarily conserved, p38-dependent signaling cascade that functions as a survival mechanism for cells in response to reactive oxygen species exposure. Ras-related small GTP-binding proteins control a wide range of cellular processes by regulating a variety of effector pathways, including prominent roles in the control of mitogen-activated protein kinase (MAPK) cascades. Although the regulatory role(s) for many Ras family GTPases are well established, the physiological function for the Rit/Rin subfamily has been lacking. Here, using both knockout mice and Drosophila models, we demonstrate an evolutionarily conserved role for Rit subfamily GTPases (mammalian Rit and Rin, and the Drosophila RIC homologue) in governing survival in response to oxidative stress. Primary embryonic fibroblasts derived from Rit knockout mice display increased apoptosis and selective disruption of MAPK signaling following reactive oxygen species (ROS) exposure but not in response to endoplasmic reticulum stress or DNA damage. These deficits include a reduction in ROS-mediated stimulation of a p38-MK2-HSP27 signaling cascade that controls Akt activation, directing Bad phosphorylation to promote cell survival. Furthermore, D-RIC null flies display increased susceptibility to environmental stresses and reduced stress-dependent p38 signaling, extending the Rit-p38 survival pathway to Drosophila. Together, our studies establish the Rit GTPases as critical regulators of an evolutionarily conserved, p38 MAPK–dependent signaling cascade that functions as an important survival mechanism for cells in response to oxidative stress.
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Affiliation(s)
- Weikang Cai
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536-0509, USA
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21
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A rit GTPase-p38 mitogen-activated protein kinase survival pathway confers resistance to cellular stress. Mol Cell Biol 2011; 31:1938-48. [PMID: 21444726 DOI: 10.1128/mcb.01380-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cells mobilize diverse signaling cascades to protect against stress-mediated injury. Ras family GTPases play a pivotal role in cell fate determination, serving as molecular switches to control the integration of multiple signaling pathways. p38 mitogen-activated protein kinase (MAPK) signaling serves as a critical fulcrum in this process, regulating networks that stimulate cellular apoptosis but also have the capacity to promote cell survival. However, relatively little is known concerning this functional dichotomy, particularly the regulation of p38-dependent survival pathways. Here, we demonstrate that the Rit GTPase promotes cell survival by directing an unexpected p38 MAPK-dependent AKT survival pathway. Following stress exposure, Rit small hairpin RNA interference (shRNAi)-treated cells display increased apoptosis and selective disruption of p38 MAPK signaling, while expression of constitutively activated Rit promotes p38-AKT-dependent cell survival. Rit, but not Ras or Rap GTPases, can associate with, and is critical for, stress-mediated activation of the scaffolded p38-MK2-HSP27-AKT prosurvival signaling complex. Together, our studies establish Rit as a central regulator of a p38 MAPK-dependent signaling cascade that functions as a critical cellular survival mechanism in response to stress.
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Stiegler NV, Krug AK, Matt F, Leist M. Assessment of Chemical-Induced Impairment of Human Neurite Outgrowth by Multiparametric Live Cell Imaging in High-Density Cultures. Toxicol Sci 2011; 121:73-87. [DOI: 10.1093/toxsci/kfr034] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Shi GX, Jin L, Andres DA. Src-dependent TrkA transactivation is required for pituitary adenylate cyclase-activating polypeptide 38-mediated Rit activation and neuronal differentiation. Mol Biol Cell 2010; 21:1597-608. [PMID: 20219970 PMCID: PMC2861617 DOI: 10.1091/mbc.e09-12-1033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a potent neuropeptide that possesses both neurotrophic and neurodevelopmental effects. Recently, the Rit GTPase was found to be activated by a novel Galpha/cAMP/exchange protein activated by cyclic AMP (Epac)-dependent signaling pathway and required for PACAP-dependent cAMP response element-binding protein activation and neuronal differentiation. However, Epac did not function as a Rit guanine nucleotide exchange factor (GEF), and the nature of the PACAP regulatory cascade remained unclear. Here, we show that PACAP-mediated Rit activation involves Src family kinase-dependent TrkA receptor transactivation. PACAP receptor (PACR1) stimulation triggered both G(i)alpha and G(s)alpha/cAMP/Epac regulatory cascades resulting in Src kinase activity, which in turn induced TrkA kinase tyrosine phosphorylation. Importantly, Src inhibition, or the lack of functional Trk receptors, was found to inhibit PACAP-mediated Rit activation, whereas constitutively active Src alone was sufficient to stimulate Rit-guanosine triphosphate levels. A single tyrosine (Y(499)) phosphorylation event was identified as critical to both PACAP-mediated transactivation and TrkA-dependent Rit activation. Accordingly, PACAP stimulation resulted in TrkA-dependent phosphorylation of both the Shc adaptor and son of sevenless (SOS)1/2 GEFs, and Rit activation was inhibited by RNA interference silencing of SOS1/2, implicating a TrkA/Shc/SOS signaling complex in Rit regulation. Together, these observations expand upon the nature of PACR1-mediated transactivation and identify TrkA-Rit signaling as a key contributor to PACAP-dependent neuronal differentiation.
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Affiliation(s)
- Geng-Xian Shi
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0509, USA.
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Saha B, Jyothi Prasanna S, Chandrasekar B, Nandi D. Gene modulation and immunoregulatory roles of interferon gamma. Cytokine 2009; 50:1-14. [PMID: 20036577 DOI: 10.1016/j.cyto.2009.11.021] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 11/02/2009] [Accepted: 11/24/2009] [Indexed: 01/19/2023]
Abstract
Interferon-gamma (IFNgamma) is a central regulator of the immune response and signals via the Janus Activated Kinase (JAK)-Signal Transducer and Activator of Transcription (STAT) pathway. Phosphorylated STAT1 homodimers translocate to the nucleus, bind to Gamma Activating Sequence (GAS) and recruit additional factors to modulate gene expression. A bioinformatics analysis revealed that greater number of putative promoters of immune related genes and also those not directly involved in immunity contain GAS compared to response elements (RE) for Interferon Regulatory Factor (IRF)1, Nuclear factor kappa B (NFkappaB) and Activator Protein (AP)1. GAS is present in putative promoters of well known IFNgamma-induced genes, IRF1, GBP1, CXCL10, and other genes identified were TLR3, VCAM1, CASP4, etc. Analysis of three microarray studies revealed that the expression of a subset of only GAS containing immune genes were modulated by IFNgamma. As a significant correlation exists between GAS containing immune genes and IFNgamma-regulated gene expression, this strategy may identify novel IFNgamma-responsive immune genes. This analysis is integrated with the literature on the roles of IFNgamma in mediating a plethora of functions: anti-microbial responses, antigen processing, inflammation, growth suppression, cell death, tumor immunity and autoimmunity. Overall, this review summarizes our present knowledge on IFNgamma mediated signaling and functions.
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Affiliation(s)
- Banishree Saha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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