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Kan HW, Chang CH, Chang YS, Ko YT, Hsieh YL. Genetic loss-of-function of activating transcription factor 3 but not C-type lectin member 5A prevents diabetic peripheral neuropathy. J Transl Med 2021; 101:1341-1352. [PMID: 34172832 PMCID: PMC8440213 DOI: 10.1038/s41374-021-00630-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022] Open
Abstract
We investigated the mediating roles of activating transcription factor 3 (ATF3), an injury marker, or C-type lectin member 5A (CLEC5A), an inflammatory response molecule, in the induction of endoplasmic reticulum (ER) stress and neuroinflammation in diabetic peripheral neuropathy in ATF3 and CLEC5A genetic knockout (aft3-/- and clec5a-/-, respectively) mice. ATF3 was expressed intranuclearly and was upregulated in mice with diabetic peripheral neuropathy (DN) and clec5a-/- mice. The DN and clec5a-/- groups also exhibited neuropathic behavior, but not in the aft3-/- group. The upregulation profiles of cytoplasmic polyadenylation element-binding protein, a protein translation-regulating molecule, and the ER stress-related molecules of inositol-requiring enzyme 1α and phosphorylated eukaryotic initiation factor 2α in the DN and clec5a-/- groups were correlated with neuropathic behavior. Ultrastructural evidence confirmed ER stress induction and neuroinflammation, including microglial enlargement and proinflammatory cytokine release, in the DN and clec5a-/- mice. By contrast, the induction of ER stress and neuroinflammation did not occur in the aft3-/- mice. Furthermore, the mRNA of reactive oxygen species-removing enzymes such as superoxide dismutase, heme oxygenase-1, and catalase were downregulated in the DN and clec5a-/- groups but were not changed in the aft3-/- group. Taken together, the results indicate that intraneuronal ATF3, but not CLEC5A, mediates the induction of ER stress and neuroinflammation associated with diabetic neuropathy.
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Affiliation(s)
- Hung-Wei Kan
- School of Medicine for International Students, College of Medicine, I-Shou University, Kaohsiung, Taiwan
| | - Chin-Hong Chang
- Department of Surgery, Chi Mei Medical Center, Tainan, Taiwan
| | - Ying-Shuang Chang
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yi-Ting Ko
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
- School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
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Nyunt T, Britton M, Wanichthanarak K, Budamagunta M, Voss JC, Wilson DW, Rutledge JC, Aung HH. Mitochondrial oxidative stress-induced transcript variants of ATF3 mediate lipotoxic brain microvascular injury. Free Radic Biol Med 2019; 143:25-46. [PMID: 31356870 PMCID: PMC6848793 DOI: 10.1016/j.freeradbiomed.2019.07.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/30/2019] [Accepted: 07/23/2019] [Indexed: 12/06/2022]
Abstract
Elevation of blood triglycerides, primarily triglyceride-rich lipoproteins (TGRL), is an independent risk factor for cardiovascular disease and vascular dementia (VaD). Accumulating evidence indicates that both atherosclerosis and VaD are linked to vascular inflammation. However, the role of TGRL in vascular inflammation, which increases risk for VaD, remains largely unknown and its underlying mechanisms are still unclear. We strived to determine the effects of postprandial TGRL exposure on brain microvascular endothelial cells, the potential risk factor of vascular inflammation, resulting in VaD. We showed in Aung et al., J Lipid Res., 2016 that postprandial TGRL lipolysis products (TL) activate mitochondrial reactive oxygen species (ROS) and increase the expression of the stress-responsive protein, activating transcription factor 3 (ATF3), which injures human brain microvascular endothelial cells (HBMECs) in vitro. In this study, we deployed high-throughput sequencing (HTS)-based RNA sequencing methods and mito stress and glycolytic rate assays with an Agilent Seahorse XF analyzer and profiled the differential expression of transcripts, constructed signaling pathways, and measured mitochondrial respiration, ATP production, proton leak, and glycolysis of HBMECs treated with TL. Conclusions: TL potentiate ROS by mitochondria which activate mitochondrial oxidative stress, decrease ATP production, increase mitochondrial proton leak and glycolysis rate, and mitochondria DNA damage. Additionally, CPT1A1 siRNA knockdown suppresses oxidative stress and prevents mitochondrial dysfunction and vascular inflammation in TL treated HBMECs. TL activates ATF3-MAPKinase, TNF, and NRF2 signaling pathways. Furthermore, the NRF2 signaling pathway which is upstream of the ATF3-MAPKinase signaling pathway, is also regulated by the mitochondrial oxidative stress. We are the first to report differential inflammatory characteristics of transcript variants 4 (ATF3-T4) and 5 (ATF3-T5) of the stress responsive gene ATF3 in HBMECs induced by postprandial TL. Specifically, our data indicates that ATF3-T4 predominantly regulates the TL-induced brain microvascular inflammation and TNF signaling. Both siRNAs of ATF3-T4 and ATF3-T5 suppress cells apoptosis and lipotoxic brain microvascular endothelial cells. These novel signaling pathways triggered by oxidative stress-responsive transcript variants, ATF3-T4 and ATF3-T5, in the brain microvascular inflammation induced by TGRL lipolysis products may contribute to pathophysiological processes of vascular dementia.
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Affiliation(s)
- Tun Nyunt
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - Monica Britton
- Genome Center and Bioinformatics Core Facility, University of California, Davis, CA, 95616, USA
| | - Kwanjeera Wanichthanarak
- West Coast Metabolomics Center, Genome Center, University of California Davis, Davis, CA, USA; Department of Biochemistry and Siriraj Metabolomics and Phenomics Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Madhu Budamagunta
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - John C Voss
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - Dennis W Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - John C Rutledge
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA
| | - Hnin H Aung
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, 95616, USA.
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Norman JE, Aung HH, Wilson DW, Rutledge JC. Inhibition of perilipin 2 expression reduces pro-inflammatory gene expression and increases lipid droplet size. Food Funct 2018; 9:6245-6256. [PMID: 30402637 PMCID: PMC6292725 DOI: 10.1039/c8fo01420e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Our lab previously demonstrated that triglyceride-rich lipoprotein (TGRL) lipolysis products induce lipid droplet formation and pro-inflammatory gene expression in monocytes. We hypothesized that the inhibition of perilipin 2 expression in THP-1 monocytes would reduce lipid droplet formation and suppress pro-inflammatory gene expression induced by TGRL lipolysis products. In the current study, we use microarray analysis to identify gene expression altered by TGRL lipolysis products in THP-1 monocytes. We confirmed the expression of selected genes by quantitative reverse transcription PCR and characterized lipid droplet formation in these cells after exposure to TGRL lipolysis products. Using siRNA inhibition of perilipin 2 expression, we examined the role of perilipin 2 in the response of THP-1 monocytes to TGRL lipolysis products. We found that perilipin 2 siRNA increased the intracellular triglyceride content, increased the size of lipid droplets, and reduced pro-atherogenic and pro-inflammatory gene expression. We saw a reduction of serum/glucocorticoid kinase 1, v-maf musculoaponeurotic fibrosarcoma oncogene homolog F (avian), chemokine (C-C motif) ligand 3, and interleukin 8 gene expression induced by TGRL lipolysis products. This study supports previous findings that reduction of perilipin 2 expression is protective against atherogenesis, while finding an unexpected increase in lipid droplet size with reduced perilipin 2 expression.
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Affiliation(s)
- Jennifer E Norman
- University of California, Davis, School of Medicine, Department of Internal Medicine, Division of Cardiovascular Medicine, GBSF 5404, 451 Health Sciences Dr. Davis, CA 95616, USA.
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Activating transcription factor 3 in cardiovascular diseases: a potential therapeutic target. Basic Res Cardiol 2018; 113:37. [PMID: 30094473 DOI: 10.1007/s00395-018-0698-6] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 08/06/2018] [Indexed: 12/12/2022]
Abstract
Cardiovascular diseases (CVDs) are the primary causes of death worldwide. Among the numerous signaling molecules involved in CVDs, transcriptional factors directly influence gene expression and play a critical role in regulating cell function and the development of diseases. Activating transcription factor (ATF) 3 is an adaptive-response gene in the ATF/cAMP responsive element-binding (CREB) protein family of transcription factors that acts as either a repressor or an activator of transcription via the formation of homodimers or heterodimers with other ATF/CREB members. A appropriate ATF3 expression is important for the normal physiology of cells, and dysfunction of ATF3 is associated with various pathophysiological responses such as inflammation, apoptosis, oxidative stress and endoplasmic reticulum stress, and diseases, including CVDs. This review focuses on the role of ATF3 in cardiac hypertrophy, heart failure, atherosclerosis, ischemic heart diseases, hypertension and diabetes mellitus to provide a novel therapeutic target for CVDs.
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Rutkowsky JM, Lee LL, Puchowicz M, Golub MS, Befroy DE, Wilson DW, Anderson S, Cline G, Bini J, Borkowski K, Knotts TA, Rutledge JC. Reduced cognitive function, increased blood-brain-barrier transport and inflammatory responses, and altered brain metabolites in LDLr -/-and C57BL/6 mice fed a western diet. PLoS One 2018; 13:e0191909. [PMID: 29444171 PMCID: PMC5812615 DOI: 10.1371/journal.pone.0191909] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/12/2018] [Indexed: 12/20/2022] Open
Abstract
Recent work suggests that diet affects brain metabolism thereby impacting cognitive function. Our objective was to determine if a western diet altered brain metabolism, increased blood-brain barrier (BBB) transport and inflammation, and induced cognitive impairment in C57BL/6 (WT) mice and low-density lipoprotein receptor null (LDLr -/-) mice, a model of hyperlipidemia and cognitive decline. We show that a western diet and LDLr -/- moderately influence cognitive processes as assessed by Y-maze and radial arm water maze. Also, western diet significantly increased BBB transport, as well as microvessel factor VIII in LDLr -/- and microglia IBA1 staining in WT, both indicators of activation and neuroinflammation. Interestingly, LDLr -/- mice had a significant increase in 18F- fluorodeoxyglucose uptake irrespective of diet and brain 1H-magnetic resonance spectroscopy showed increased lactate and lipid moieties. Metabolic assessments of whole mouse brain by GC/MS and LC/MS/MS showed that a western diet altered brain TCA cycle and β-oxidation intermediates, levels of amino acids, and complex lipid levels and elevated proinflammatory lipid mediators. Our study reveals that the western diet has multiple impacts on brain metabolism, physiology, and altered cognitive function that likely manifest via multiple cellular pathways.
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Affiliation(s)
- Jennifer M. Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
- * E-mail:
| | - Linda L. Lee
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California, United States of America
| | - Michelle Puchowicz
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Mari S. Golub
- Department of Environmental Toxicology, University of California, Davis, California, United States of America
| | - Douglas E. Befroy
- Magnetic Resonance Research Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Dennis W. Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Steven Anderson
- Department of Physiology and Membrane Biology, University of California, Davis, California, United States of America
| | - Gary Cline
- Department of Endocrinology, Yale University, New Haven, Connecticut, United States of America
| | - Jason Bini
- Yale PET Center, Department of Diagnostic Radiology, Yale University, New Haven, Connecticut, United States of America
| | - Kamil Borkowski
- West Coast Metabolomics Center, Genome Center, University of California, Davis, California, United States of America
| | - Trina A. Knotts
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - John C. Rutledge
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
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Lee LL, Aung HH, Wilson DW, Anderson SE, Rutledge JC, Rutkowsky JM. Triglyceride-rich lipoprotein lipolysis products increase blood-brain barrier transfer coefficient and induce astrocyte lipid droplets and cell stress. Am J Physiol Cell Physiol 2017; 312:C500-C516. [PMID: 28077357 DOI: 10.1152/ajpcell.00120.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/19/2022]
Abstract
Elevation of blood triglycerides, primarily as triglyceride-rich lipoproteins (TGRL), has been linked to cerebrovascular inflammation, vascular dementia, and Alzheimer's disease (AD). Brain microvascular endothelial cells and astrocytes, two cell components of the neurovascular unit, participate in controlling blood-brain barrier (BBB) permeability and regulating neurovascular unit homeostasis. Our studies showed that infusion of high physiological concentrations of TGRL lipolysis products (TGRL + lipoprotein lipase) activate and injure brain endothelial cells and transiently increase the BBB transfer coefficient (Ki = permeability × surface area/volume) in vivo. However, little is known about how blood lipids affect astrocyte lipid accumulation and inflammation. To address this, we first demonstrated TGRL lipolysis products increased lipid droplet formation in cultured normal human astrocytes. We then evaluated the transcriptional pathways activated in astrocytes by TGRL lipolysis products and found upregulated stress and inflammatory-related genes including activating transcription factor 3 (ATF3), macrophage inflammatory protein-3α (MIP-3α), growth differentiation factor-15 (GDF15), and prostaglandin-endoperoxide synthase 2 (COX2). TGRL lipolysis products also activated the JNK/cJUN/ATF3 pathway, induced endoplasmic reticulum stress protein C/EBP homologous protein (CHOP), and the NF-κB pathway, while increasing secretion of MIP-3α, GDF15, and IL-8. Thus our results demonstrate TGRL lipolysis products increase the BBB transfer coefficient (Ki), induce astrocyte lipid droplet formation, activate cell stress pathways, and induce secretion of inflammatory cytokines. Our observations are consistent with evidence for lipid-induced neurovascular injury and inflammation, and we, therefore, speculate that lipid-induced astrocyte injury could play a role in cognitive decline.
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Affiliation(s)
- Linda L Lee
- Department of Internal Medicine, University of California, Davis, California
| | - Hnin H Aung
- Department of Internal Medicine, University of California, Davis, California
| | - Dennis W Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California; and
| | - Steven E Anderson
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - John C Rutledge
- Department of Internal Medicine, University of California, Davis, California
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Aung HH, Altman R, Nyunt T, Kim J, Nuthikattu S, Budamagunta M, Voss JC, Wilson D, Rutledge JC, Villablanca AC. Lipotoxic brain microvascular injury is mediated by activating transcription factor 3-dependent inflammatory and oxidative stress pathways. J Lipid Res 2016; 57:955-68. [PMID: 27087439 DOI: 10.1194/jlr.m061853] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 01/10/2023] Open
Abstract
Dysfunction of the cerebrovasculature plays an important role in vascular cognitive impairment (VCI). Lipotoxic injury of the systemic endothelium in response to hydrolyzed triglyceride-rich lipoproteins (TGRLs; TGRL lipolysis products) or a high-fat Western diet (WD) suggests similar mechanisms may be present in brain microvascular endothelium. We investigated the hypothesis that TGRL lipolysis products cause lipotoxic injury to brain microvascular endothelium by generating increased mitochondrial superoxide radical generation, upregulation of activating transcription factor 3 (ATF3)-dependent inflammatory pathways, and activation of cellular oxidative stress and apoptotic pathways. Human brain microvascular endothelial cells were treated with human TGRL lipolysis products that induced intracellular lipid droplet formation, mitochondrial superoxide generation, ATF3-dependent transcription of proinflammatory, stress response, and oxidative stress genes, as well as activation of proapoptotic cascades. Male apoE knockout mice were fed a high-fat/high-cholesterol WD for 2 months, and brain microvessels were isolated by laser capture microdissection. ATF3 gene transcription was elevated 8-fold in the hippocampus and cerebellar brain region of the WD-fed animals compared with chow-fed control animals. The microvascular injury phenotypes observed in vitro and in vivo were similar. ATF3 plays an important role in mediating brain microvascular responses to acute and chronic lipotoxic injury and may be an important preventative and therapeutic target for endothelial dysfunction in VCI.
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Affiliation(s)
- Hnin Hnin Aung
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
| | - Robin Altman
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
| | - Tun Nyunt
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
| | - Jeffrey Kim
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
| | | | - Madhu Budamagunta
- Department of Biochemistry and Molecular Medicine, School of Medicine
| | - John C Voss
- Department of Biochemistry and Molecular Medicine, School of Medicine
| | - Dennis Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616
| | - John C Rutledge
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
| | - Amparo C Villablanca
- Division of Cardiovascular Medicine, Department of Internal Medicine School of Medicine
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