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Caputo M, Andersson E, Xia Y, Hou W, Cansby E, Erikson M, Lind DE, Hallberg B, Amrutkar M, Mahlapuu M. Genetic Ablation of STE20-Type Kinase MST4 Does Not Alleviate Diet-Induced MASLD Susceptibility in Mice. Int J Mol Sci 2024; 25:2446. [PMID: 38397122 PMCID: PMC10888586 DOI: 10.3390/ijms25042446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Metabolic dysfunction-associated steatotic liver disease (MASLD) and its advanced subtype, metabolic dysfunction-associated steatohepatitis (MASH), have emerged as the most common chronic liver disease worldwide, yet there is no targeted pharmacotherapy presently available. This study aimed to investigate the possible in vivo function of STE20-type protein kinase MST4, which was earlier implicated in the regulation of hepatocellular lipotoxic milieu in vitro, in the control of the diet-induced impairment of systemic glucose and insulin homeostasis as well as MASLD susceptibility. Whole-body and liver-specific Mst4 knockout mice were generated by crossbreeding conditional Mst4fl/fl mice with mice expressing Cre recombinase under the Sox2 or Alb promoters, respectively. To replicate the environment in high-risk subjects, Mst4-/- mice and their wild-type littermates were fed a high-fat or a methionine-choline-deficient (MCD) diet. Different in vivo tests were conducted in obese mice to describe the whole-body metabolism. MASLD progression in the liver and lipotoxic damage to adipose tissue, kidney, and skeletal muscle were analyzed by histological and immunofluorescence analysis, biochemical assays, and protein and gene expression profiling. In parallel, intracellular fat storage and oxidative stress were assessed in primary mouse hepatocytes, where MST4 was silenced by small interfering RNA. We found that global MST4 depletion had no effect on body weight or composition, locomotor activity, whole-body glucose tolerance or insulin sensitivity in obese mice. Furthermore, we observed no alterations in lipotoxic injuries to the liver, adipose, kidney, or skeletal muscle tissue in high-fat diet-fed whole-body Mst4-/- vs. wild-type mice. Liver-specific Mst4-/- mice and wild-type littermates displayed a similar severity of MASLD when subjected to an MCD diet, as evidenced by equal levels of steatosis, inflammation, hepatic stellate cell activation, fibrosis, oxidative/ER stress, and apoptosis in the liver. In contrast, the in vitro silencing of MST4 effectively protected primary mouse hepatocytes against ectopic lipid accumulation and oxidative cell injury triggered by exposure to fatty acids. In summary, these results suggest that the genetic ablation of MST4 in mice does not mitigate the initiation or progression of MASLD and has no effect on systemic glucose or insulin homeostasis in the context of nutritional stress. The functional compensation for the genetic loss of MST4 by yet undefined mechanisms may contribute to the apparent discrepancy between in vivo and in vitro phenotypic consequences of MST4 silencing.
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Affiliation(s)
- Mara Caputo
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Emma Andersson
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Ying Xia
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Wei Hou
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Emmelie Cansby
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Max Erikson
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Dan Emil Lind
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Bengt Hallberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Manoj Amrutkar
- Department of Pathology, Oslo University Hospital Rikshospitalet, 0372 Oslo, Norway
| | - Margit Mahlapuu
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
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Jazieh C, Arabi TZ, Asim Z, Sabbah BN, Alsaud AW, Alkattan K, Yaqinuddin A. Unraveling the epigenetic fabric of type 2 diabetes mellitus: pathogenic mechanisms and therapeutic implications. Front Endocrinol (Lausanne) 2024; 15:1295967. [PMID: 38323108 PMCID: PMC10845351 DOI: 10.3389/fendo.2024.1295967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/04/2024] [Indexed: 02/08/2024] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a rapidly escalating global health concern, with its prevalence projected to increase significantly in the near future. This review delves into the intricate role of epigenetic modifications - including DNA methylation, histone acetylation, and micro-ribonucleic acid (miRNA) expression - in the pathogenesis and progression of T2DM. We critically examine how these epigenetic changes contribute to the onset and exacerbation of T2DM by influencing key pathogenic processes such as obesity, insulin resistance, β-cell dysfunction, cellular senescence, and mitochondrial dysfunction. Furthermore, we explore the involvement of epigenetic dysregulation in T2DM-associated complications, including diabetic retinopathy, atherosclerosis, neuropathy, and cardiomyopathy. This review highlights recent studies that underscore the diagnostic and therapeutic potential of targeting epigenetic modifications in T2DM. We also provide an overview of the impact of lifestyle factors such as exercise and diet on the epigenetic landscape of T2DM, underscoring their relevance in disease management. Our synthesis of the current literature aims to illuminate the complex epigenetic underpinnings of T2DM, offering insights into novel preventative and therapeutic strategies that could revolutionize its management.
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Guan J, Fan Y, Wang S, Zhou F. Functions of MAP3Ks in antiviral immunity. Immunol Res 2023; 71:814-832. [PMID: 37286768 PMCID: PMC10247270 DOI: 10.1007/s12026-023-09401-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 06/01/2023] [Indexed: 06/09/2023]
Abstract
Immune signal transduction is crucial to the body's defense against viral infection. Recognition of pathogen-associated molecular patterns by pattern recognition receptors (PRRs) activates the transcription of interferon regulators and nuclear factor-κB (NF-κB); this promotes the release of interferons and inflammatory factors. Efficient regulation of type I interferon and NF-κB signaling by members of the mitogen-activated protein (MAP) kinase kinase kinase (MAP3K) family plays an important role in antiviral immunity. Elucidating the specific roles of MAP3K activation during viral infection is essential to develop effective antiviral therapies. In this review, we outline the specific regulatory mechanisms of MAP3Ks in antiviral immunity and discuss the feasibility of targeting MAP3Ks for the treatment of virus-induced diseases.
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Affiliation(s)
- Jizhong Guan
- Institutes of Biology and Medical Science, Soochow University, Suzhou, 215123, China
| | - Yao Fan
- The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518033, China
| | - Shuai Wang
- Institutes of Biology and Medical Science, Soochow University, Suzhou, 215123, China
| | - Fangfang Zhou
- Institutes of Biology and Medical Science, Soochow University, Suzhou, 215123, China.
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Xia Y, Andersson E, Caputo M, Cansby E, Sedda F, Font-Gironès F, Ruud J, Kurhe Y, Hallberg B, Marschall HU, Asterholm IW, Romeo S, Blüher M, Mahlapuu M. Knockout of STE20-type kinase TAOK3 does not attenuate diet-induced NAFLD development in mice. Mol Med 2023; 29:138. [PMID: 37864157 PMCID: PMC10589923 DOI: 10.1186/s10020-023-00738-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/11/2023] [Indexed: 10/22/2023] Open
Abstract
OBJECTIVE Non-alcoholic fatty liver disease (NAFLD), the primary hepatic consequence of obesity, is affecting about 25% of the global adult population. The aim of this study was to examine the in vivo role of STE20-type protein kinase TAOK3, which has been previously reported to regulate hepatocellular lipotoxicity in vitro, in the development of NAFLD and systemic insulin resistance in the context of obesity. METHODS Taok3 knockout mice and wild-type littermates were challenged with a high-fat diet. Various in vivo tests were performed to characterize the whole-body metabolism. NAFLD progression in the liver, and lipotoxic damage in adipose tissue, kidney, and skeletal muscle were compared between the genotypes by histological assessment, immunofluorescence microscopy, protein and gene expression profiling, and biochemical assays. Intracellular lipid accumulation and oxidative/ER stress were analyzed in cultured human and mouse hepatocytes where TAOK3 was knocked down by small interfering RNA. The expression of TAOK3-related STE20-type kinases was quantified in different organs from high-fat diet-fed Taok3-/- and wild-type mice. RESULTS TAOK3 deficiency had no impact on body weight or composition, food consumption, locomotor activity, or systemic glucose or insulin homeostasis in obese mice. Consistently, Taok3-/- mice and wild-type littermates developed a similar degree of high-fat diet-induced liver steatosis, inflammation, and fibrosis, and we detected no difference in lipotoxic damage of adipose tissue, kidney, or skeletal muscle when comparing the two genotypes. In contrast, the silencing of TAOK3 in vitro markedly suppressed ectopic lipid accumulation and metabolic stress in mouse and human hepatocytes. Interestingly, the hepatic mRNA abundance of several TAOK3-related kinases, which have been previously implicated to increase the risk of NAFLD susceptibility, was significantly elevated in Taok3-/- vs. wild-type mice. CONCLUSIONS In contrast to the in vitro observations, genetic deficiency of TAOK3 in mice failed to mitigate the detrimental metabolic consequences of chronic exposure to dietary lipids, which may be partly attributable to the activation of liver-specific compensation response for the genetic loss of TAOK3 by related STE20-type kinases.
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Affiliation(s)
- Ying Xia
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Emma Andersson
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Mara Caputo
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Emmelie Cansby
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Francesca Sedda
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ferran Font-Gironès
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Johan Ruud
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Yeshwant Kurhe
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Bengt Hallberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Hanns-Ulrich Marschall
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ingrid Wernstedt Asterholm
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Stefano Romeo
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity, and Vascular Research (HI-MAG) of the Helmholtz Zentrum München, University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - Margit Mahlapuu
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden.
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Weldemariam MM, Sudhir PR, Woo J, Zhang Q. Effects of multiple stressors on pancreatic human islets proteome reveal new insights into the pathways involved. Proteomics 2023; 23:e2300022. [PMID: 37489002 PMCID: PMC10591809 DOI: 10.1002/pmic.202300022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 07/13/2023] [Accepted: 07/17/2023] [Indexed: 07/26/2023]
Abstract
Pancreatic β-cell dysfunction is an early hallmark of type 1 diabetes mellitus. Among the potentially critical factors that cause β-cell dysfunction are cytokine attack, glucotoxicity, induction of endoplasmic reticulum (ER) or mitochondria stress. However, the exact molecular mechanism underlying β-cell's inability to maintain glucose homeostasis under severe stresses is unknown. This study used proinflammatory cytokines, thapsigargin, and rotenone in the presence of high concentration glucose to mimicking the conditions experienced by dysfunctional β-cells in human pancreatic islets, and profiled the alterations to the islet proteome with TMT-based proteomics. The results were further verified with label-free quantitative proteomics. The differentially expressed proteins under stress conditions reveal that immune related pathways are mostly perturbed by cytokines, while the respiratory electron transport chains and protein processing in ER pathways by rotenone. Thapsigargin together with high glucose induces dramatic increases of proteins in lipid synthesis and peroxisomal protein import pathways, with energy metabolism and vesicle secretion related pathways downregulated. High concentration glucose, on the other hand, alleviated complex I inhibition induced by rotenone. Our results contribute to a more comprehensive understanding of the molecular events involved in β-cell dysfunction.
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Affiliation(s)
- Mehari Muuz Weldemariam
- Center for Translational Biomedical Research, University of North Carolina at Greensboro, North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
| | - Putty-Reddy Sudhir
- Center for Translational Biomedical Research, University of North Carolina at Greensboro, North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
| | - Jongmin Woo
- Center for Translational Biomedical Research, University of North Carolina at Greensboro, North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
| | - Qibin Zhang
- Center for Translational Biomedical Research, University of North Carolina at Greensboro, North Carolina Research Campus, Kannapolis, North Carolina 28081, United States
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
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Yoder MD, Van Osten S, Weber GF. Gene expression analysis of the Tao kinase family of Ste20p-like map kinase kinase kinases during early embryonic development in Xenopus laevis. Gene Expr Patterns 2023; 48:119318. [PMID: 37011704 PMCID: PMC10453956 DOI: 10.1016/j.gep.2023.119318] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/15/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023]
Abstract
Development of the vertebrate embryo requires strict coordination of a highly complex series of signaling cascades, that drive cell proliferation, differentiation, migration, and the general morphogenetic program. Members of the Map kinase signaling pathway are repeatedly required throughout development to activate the downstream effectors, ERK, p38, and JNK. Regulation of these pathways occurs at many levels in the signaling cascade, with the Map3Ks playing an essential role in target selection. The thousand and one amino acid kinases (Taoks) are Map3Ks that have been shown to activate both p38 and JNK and are linked to neurodevelopment in both invertebrate and vertebrate organisms. In vertebrates, there are three Taok paralogs (Taok1, Taok2, and Taok3) which have not yet been ascribed a role in early development. Here we describe the spatiotemporal expression of Taok1, Taok2, and Taok3 in the model organism Xenopus laevis. The X. laevis Tao kinases share roughly 80% identity to each other, with the bulk of the conservation in the kinase domain. Taok1 and Taok3 are highly expressed in pre-gastrula and gastrula stage embryos, with initial expression localized to the animal pole and later expression in the ectoderm and mesoderm. All three Taoks are expressed in the neural and tailbud stages, with overlapping expression in the neural tube, notochord, and many anterior structures (including branchial arches, brain, otic vesicles, and eye). The expression patterns described here provide evidence that the Tao kinases may play a central role in early development, in addition to their function during neural development, and establish a framework to better understand the developmental roles of Tao kinase signaling.
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Affiliation(s)
- Michael D Yoder
- Department of Biology, University of Central Arkansas, Conway, AR, 72035, USA.
| | - Steven Van Osten
- Sciences Division, Brandywine Campus, The Pennsylvania State University, Media, PA, 19063, USA.
| | - Gregory F Weber
- Department of Biology, University of Indianapolis, Indianapolis, IN, 46227, USA.
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Xia Y, Andersson E, Anand SK, Cansby E, Caputo M, Kumari S, Porosk R, Kilk K, Nair S, Marschall HU, Blüher M, Mahlapuu M. Silencing of STE20-type kinase TAOK1 confers protection against hepatocellular lipotoxicity through metabolic rewiring. Hepatol Commun 2023; 7:02009842-202304010-00004. [PMID: 36930872 PMCID: PMC10027040 DOI: 10.1097/hc9.0000000000000037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/19/2022] [Indexed: 03/19/2023] Open
Abstract
BACKGROUND NAFLD has become the leading cause of chronic liver disease worldwide afflicting about one quarter of the adult population. NASH is a severe subtype of NAFLD, which in addition to hepatic steatosis connotes liver inflammation and hepatocyte ballooning. In light of the exponentially increasing prevalence of NAFLD, it is imperative to gain a better understanding of its molecular pathogenesis. The aim of this study was to examine the potential role of STE20-type kinase TAOK1 -a hepatocellular lipid droplet-associated protein-in the regulation of liver lipotoxicity and NAFLD etiology. METHODS The correlation between TAOK1 mRNA expression in liver biopsies and the severity of NAFLD was evaluated in a cohort of 62 participants. Immunofluorescence microscopy was applied to describe the subcellular localization of TAOK1 in human and mouse hepatocytes. Metabolic reprogramming and oxidative/endoplasmic reticulum stress were investigated in immortalized human hepatocytes, where TAOK1 was overexpressed or silenced by small interfering RNA, using functional assays, immunofluorescence microscopy, and colorimetric analysis. Migration, invasion, and epithelial-mesenchymal transition were examined in TAOK1-deficient human hepatoma-derived cells. Alterations in hepatocellular metabolic and pro-oncogenic signaling pathways were assessed by immunoblotting. RESULTS We observed a positive correlation between the TAOK1 mRNA abundance in human liver biopsies and key hallmarks of NAFLD (i.e., hepatic steatosis, inflammation, and ballooning). Furthermore, we found that TAOK1 protein fully colocalized with intracellular lipid droplets in human and mouse hepatocytes. The silencing of TAOK1 alleviated lipotoxicity in cultured human hepatocytes by accelerating lipid catabolism (mitochondrial β-oxidation and triacylglycerol secretion), suppressing lipid anabolism (fatty acid influx and lipogenesis), and mitigating oxidative/endoplasmic reticulum stress, and the opposite changes were detected in TAOK1-overexpressing cells. We also found decreased proliferative, migratory, and invasive capacity, as well as lower epithelial-mesenchymal transition in TAOK1-deficient human hepatoma-derived cells. Mechanistic studies revealed that TAOK1 knockdown inhibited ERK and JNK activation and repressed acetyl-CoA carboxylase (ACC) protein abundance in human hepatocytes. CONCLUSIONS Together, we provide the first experimental evidence supporting the role of hepatic lipid droplet-decorating kinase TAOK1 in NAFLD development through mediating fatty acid partitioning between anabolic and catabolic pathways, regulating oxidative/endoplasmic reticulum stress, and modulating metabolic and pro-oncogenic signaling.
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Affiliation(s)
- Ying Xia
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Emma Andersson
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Sumit K Anand
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Emmelie Cansby
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Mara Caputo
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Sima Kumari
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Rando Porosk
- Department of Biochemistry, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
| | - Kalle Kilk
- Department of Biochemistry, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
| | - Syam Nair
- Institute of Neuroscience and Physiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Hanns-Ulrich Marschall
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity, and Vascular Research (HI-MAG) of the Helmholtz Zentrum München, University Hospital Leipzig, University of Leipzig, Leipzig, Germany
| | - Margit Mahlapuu
- Department of Chemistry and Molecular Biology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
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Anand SK, Caputo M, Xia Y, Andersson E, Cansby E, Kumari S, Henricsson M, Porosk R, Keuenhof KS, Höög JL, Nair S, Marschall HU, Blüher M, Mahlapuu M. Inhibition of MAP4K4 Signaling Initiaties Metabolic Reprogramming to Protect Hepatocytes from Lipotoxic Damage. J Lipid Res 2022; 63:100238. [PMID: 35679904 PMCID: PMC9293639 DOI: 10.1016/j.jlr.2022.100238] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 11/28/2022] Open
Abstract
The primary hepatic consequence of obesity is non-alcoholic fatty liver disease (NAFLD), affecting about 25% of the global adult population. Non-alcoholic steatohepatitis (NASH) is a severe form of NAFLD characterized by liver lipid accumulation, inflammation, and hepatocyte ballooning, with a different degree of hepatic fibrosis. In the light of rapidly increasing prevalence of NAFLD and NASH, there is an urgent need for improved understanding of the molecular pathogenesis of these diseases. The aim of this study was to decipher the possible role of STE20-type kinase MAP4K4 in the regulation of hepatocellular lipotoxicity and susceptibility to NAFLD. We found that MAP4K4 mRNA expression in human liver biopsies was positively correlated with key hallmarks of NAFLD (i.e., liver steatosis, lobular inflammation, hepatocellular ballooning, and fibrosis). We also found that the silencing of MAP4K4 suppressed lipid deposition in human hepatocytes by stimulating β-oxidation and triacylglycerol secretion, while attenuating fatty acid influx and lipid synthesis. Furthermore, downregulation of MAP4K4 markedly reduced the glycolysis rate and lowered incidences of oxidative/endoplasmic reticulum stress. In parallel, we observed suppressed JNK and ERK and increased AKT phosphorylation in MAP4K4-deficient hepatocytes. Together, these results provide the first experimental evidence supporting the potential involvement of STE20-type kinase MAP4K4 as a component of the hepatocellular lipotoxic milieu promoting NAFLD susceptibility.
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Affiliation(s)
- Sumit Kumar Anand
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Mara Caputo
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ying Xia
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Emma Andersson
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Emmelie Cansby
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Sima Kumari
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Marcus Henricsson
- Biomarker Discovery and Development, Research and Early Development, Cardiovascular, Renal, and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden; Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Rando Porosk
- Department of Biochemistry, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
| | - Katharina Susanne Keuenhof
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Johanna Louise Höög
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Syam Nair
- Institute of Neuroscience and Physiology, and Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Hanns-Ulrich Marschall
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity, and Vascular Research (HI-MAG) of the Helmholtz Zentrum München, University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - Margit Mahlapuu
- Department of Chemistry and Molecular Biology, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden.
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Hepatocyte-specific activity of TSC22D4 triggers progressive NAFLD by impairing mitochondrial function. Mol Metab 2022; 60:101487. [PMID: 35378329 PMCID: PMC9034319 DOI: 10.1016/j.molmet.2022.101487] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 11/24/2022] Open
Abstract
Objective Fibrotic organ responses have recently been identified as long-term complications in diabetes. Indeed, insulin resistance and aberrant hepatic lipid accumulation represent driving features of progressive non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis and non-alcoholic steatohepatitis (NASH) to fibrosis. Effective pharmacological regimens to stop progressive liver disease are still lacking to-date. Methods Based on our previous discovery of transforming growth factor beta-like stimulated clone (TSC)22D4 as a key driver of insulin resistance and glucose intolerance in obesity and type 2 diabetes, we generated a TSC22D4-hepatocyte specific knockout line (TSC22D4-HepaKO) and exposed mice to control or NASH diet models. Mechanistic insights were generated by metabolic phenotyping and single-nuclei RNA sequencing. Results Hepatic TSC22D4 expression was significantly correlated with markers of liver disease progression and fibrosis in both murine and human livers. Indeed, hepatic TSC22D4 levels were elevated in human NASH patients as well as in several murine NASH models. Specific genetic deletion of TSC22D4 in hepatocytes led to reduced liver lipid accumulation, improvements in steatosis and inflammation scores and decreased apoptosis in mice fed a lipogenic MCD diet. Single-nuclei RNA sequencing revealed a distinct TSC22D4-dependent gene signature identifying an upregulation of mitochondrial-related processes in hepatocytes upon loss of TSC22D4. An enrichment of genes involved in the TCA cycle, mitochondrial organization, and triglyceride metabolism underscored the hepatocyte-protective phenotype and overall decreased liver damage as seen in mouse models of hepatocyte-selective TSC22D4 loss-of-function. Conclusions Together, our data uncover a new connection between targeted depletion of TSC22D4 and intrinsic metabolic processes in progressive liver disease. Hepatocyte-specific reduction of TSC22D4 improves hepatic steatosis and promotes hepatocyte survival via mitochondrial-related mechanisms thus paving the way for targeted therapies. TSC22D4 is significantly upregulated in both patients with NASH and liver fibrosis and in murine models of NAFLD. Hepatocyte-specific knockdown of TSC22D4 results in reduced steatosis and hepatocyte damage in MCD diet fed mice. Single-nuclei RNA sequencing from TSC22D4-HepaKO mice reveals enrichment in lipid metabolism and OXPHOS pathways. Loss of TSC22D4 increases the oxidative consumption rate and upregulates mitochondrial maintenance genes in hepatocytes. TSC22D4 expression negatively correlates with mitochondrial targets in NASH patients.
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