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Keratin 8/18 Regulate the Akt Signaling Pathway. Int J Mol Sci 2021; 22:ijms22179227. [PMID: 34502133 PMCID: PMC8430995 DOI: 10.3390/ijms22179227] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/19/2021] [Accepted: 08/24/2021] [Indexed: 11/17/2022] Open
Abstract
Keratin 8 and keratin 18 (K8/K18) are intermediate filament proteins that form the obligate heteropolymers in hepatocytes and protect the liver against toxins. The mechanisms of protection include the regulation of signaling pathway associated with cell survival. Previous studies show K8/K18 binding with Akt, which is a well-known protein kinase involved in the cell survival signaling pathway. However, the role of K8/K18 in the Akt signaling pathway is unclear. In this study, we found that K8/K18-Akt binding is downregulated by K8/K18 phosphorylation, specifically phosphorylation of K18 ser7/34/53 residues, whereas the binding is upregulated by K8 gly-62-cys mutation. K8/K18 expression in cultured cell system tends to enhance the stability of the Akt protein. A comparison of the Akt signaling pathway in a mouse system with liver damage shows that the pathway is downregulated in K18-null mice compared with nontransgenic mice. K18-null mice with Fas-induced liver damage show enhanced apoptosis combined with the downregulation of the Akt signaling pathway, i.e., lower phosphorylation levels of GSK3β and NFκB, which are the downstream signaling factors in the Akt signaling pathway, in K18-null mice compared with the control mice. Our study indicates that K8/K18 expression protects mice from liver damage by participating in enhancing the Akt signaling pathway.
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Kim S, Lim Y, Lee SY, Yoon HN, Yi H, Jang KH, Ku NO. Keratin 8 mutations in transgenic mice predispose to lung injury. J Cell Sci 2021; 134:jcs250167. [PMID: 34342355 DOI: 10.1242/jcs.250167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 06/28/2021] [Indexed: 11/20/2022] Open
Abstract
Keratin 8 (K8) is the cytoskeletal intermediate filament protein of simple-type epithelia. Mutations in K8 predispose the affected individual and transgenic mouse to liver disease. However, the role of K8 in the lung has not been reported in mutant transgenic mouse models. Here, we investigated the susceptibility of two different transgenic mice expressing K8 Gly62-Cys (Gly62 replaced with Cys) or Ser74-Ala (Ser74 replaced with Ala) to lung injury. The mutant transgenic mice were highly susceptible to two independent acute and chronic lung injuries compared with control mice. Both K8 Gly62-Cys mice and K8 Ser74-Ala mice showed markedly increased mouse lethality (∼74% mutant mice versus ∼34% control mice) and more severe lung damage, with increased inflammation and apoptosis, under L-arginine-mediated acute lung injury. Moreover, the K8 Ser74-Ala mice had more severe lung damage, with extensive hemorrhage and prominent fibrosis, under bleomycin-induced chronic lung injury. Our study provides the first direct evidence that K8 mutations predispose to lung injury in transgenic mice.
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Affiliation(s)
- Sujin Kim
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - Younglan Lim
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - So-Young Lee
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - Han-Na Yoon
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - Hayan Yi
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - Kwi-Hoon Jang
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
| | - Nam-On Ku
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 03722, Korea
- Department of Bio-Convergence ISED, Underwood International College, Yonsei University, Seoul 03722, Korea
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Lim Y, Ku NO. Revealing the Roles of Keratin 8/18-Associated Signaling Proteins Involved in the Development of Hepatocellular Carcinoma. Int J Mol Sci 2021; 22:6401. [PMID: 34203895 PMCID: PMC8232640 DOI: 10.3390/ijms22126401] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/08/2021] [Accepted: 06/11/2021] [Indexed: 02/08/2023] Open
Abstract
Although hepatocellular carcinoma (HCC) is developed with various etiologies, protection of hepatocytes seems basically essential to prevent the incidence of HCC. Keratin 8 and keratin 18 (K8/K18) are cytoskeletal intermediate filament proteins that are expressed in hepatocytes. They maintain the cell shape and protect cells under stress conditions. Their protective roles in liver damage have been described in studies of mouse models, and K8/K18 mutation frequency in liver patients. Interestingly, K8/K18 bind to signaling proteins such as transcription factors and protein kinases involved in HCC development. Since K8/K18 are abundant cytoskeletal proteins, K8/K18 binding with the signaling factors can alter the availability of the factors. Herein, we discuss the potential roles of K8/K18 in HCC development.
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Affiliation(s)
- Younglan Lim
- Interdisciplinary Program of Integrated OMICS for Biomedical Sciences, Yonsei University, Seoul 03722, Korea;
| | - Nam-On Ku
- Interdisciplinary Program of Integrated OMICS for Biomedical Sciences, Yonsei University, Seoul 03722, Korea;
- Department of Bio-Convergence ISED, Underwood International College, Yonsei University, Seoul 03722, Korea
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Wen F, Xia Q, Zhang H, Shia H, Rajesh A, Wu Y, Yang Y, Yang Z. Resistin Activates p65 Pathway and Reduces Glycogen Content through Keratin 8. Int J Endocrinol 2020; 2020:9767926. [PMID: 32508919 PMCID: PMC7251471 DOI: 10.1155/2020/9767926] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/28/2020] [Accepted: 04/11/2020] [Indexed: 01/27/2023] Open
Abstract
Resistin is associated with metabolic syndrome and inflammatory conditions. Many studies have suggested that resistin inhibits the accumulation of glycogen; however, the exact mechanisms of resistin-induced decrease in glycogen content remain unclear. Keratin 8 is a typical epithelial intermediate filament protein, but numerous studies suggest a vital role of K8 in glucose metabolism. However, it is still not known whether K8 participates in the mediation of resistin-induced reduction of cellular glycogen accumulation. In this study, we found that resistin upregulated expression of the p65 subunit of NF-κB, which led to the promotion of K8 transcriptional expression; in turn, the expression of K8 inhibited glycogen accumulation in HepG2 cells.
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Affiliation(s)
- Fengyun Wen
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, China
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Qiao Xia
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Hui Zhang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, China
| | - Haipeng Shia
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, China
| | - Amin Rajesh
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, 36849-5501 Auburn, Alabama, USA
| | - Yanling Wu
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yi Yang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Zaiqing Yang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, China
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Lee SY, Kim S, Lim Y, Yoon HN, Ku NO. Keratins regulate Hsp70-mediated nuclear localization of p38 mitogen-activated protein kinase. J Cell Sci 2019; 132:jcs.229534. [PMID: 31427430 DOI: 10.1242/jcs.229534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 08/12/2019] [Indexed: 12/31/2022] Open
Abstract
Intermediate filament protein keratin 8 (K8) binds to heat shock protein 70 (Hsp70) and p38 MAPK, and is phosphorylated at Ser74 by p38α (MAPK14, hereafter p38). However, a p38 binding site on K8 and the molecular mechanism of K8-p38 interaction related to Hsp70 are unknown. Here, we identify a p38 docking site on K8 (Arg148/149 and Leu159/161) that is highly conserved in other intermediate filaments. A docking-deficient K8 mutation caused increased p38-Hsp70 interaction and enhanced p38 nuclear localization, indicating that the p38 dissociated from mutant K8 makes a complex with Hsp70, which is known as a potential chaperone for p38 nuclear translocation. Comparison of p38 MAPK binding with keratin variants associated with liver disease showed that the K18 I150V variant dramatically reduced binding with p38, which is similar to the effect of the p38 docking-deficient mutation on K8. Because the p38 docking site on K8 (Arg148/149 and Leu159/161) and the K18 Ile150 residue are closely localized in the parallel K8/K18 heterodimer, the K18 I150V mutation might interfere with K8-p38 interaction. These findings show that keratins, functioning as cytoplasmic anchors for p38, modulate p38 nuclear localization and thereby might affect a number of p38-mediated signal transduction pathways.
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Affiliation(s)
- So-Young Lee
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 120-749, Korea
| | - Sujin Kim
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 120-749, Korea
| | - Younglan Lim
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 120-749, Korea
| | - Han-Na Yoon
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 120-749, Korea
| | - Nam-On Ku
- Interdisciplinary Program of Integrated OMICS for Biomedical Science, Graduate School, Yonsei University, Seoul 120-749, Korea .,Department of Bio-Convergence ISED, Underwood International College, Yonsei University, Seoul 120-749, Korea
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Yoon HN, Yoon SY, Hong JH, Ku NO. A mutation in keratin 18 that causes caspase-digestion resistance protects homozygous transgenic mice from hepatic apoptosis and injury. J Cell Sci 2017; 130:2541-2550. [PMID: 28606991 DOI: 10.1242/jcs.187492] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/06/2017] [Indexed: 12/14/2022] Open
Abstract
Cytoskeletal keratin 18 (K18) undergoes caspase-mediated digestion during apoptosis, which leads to dramatic disassembly of keratin filaments. We studied the significance of K18 caspase digestion in a mouse model and generated transgenic mice expressing the human K18 caspase digestion-resistant double-mutant K18-D238/397E in a mouse (m) K18-null background, and compared their response to injury mediated by administration of antibody against tumor necrosis factor receptor superfamily member 6 (Fas), anti-FasAb. Notably, K18-D238/397E;mK18-null mice were significantly more resistant to anti-FasAb-induced injury as compared with K18-WT;mK18-null mice (23% vs 57% lethality, respectively; P<0.001). The same applied when the toxin microcystin-LR (MLR) was used to induce liver injury, i.e. lethality of K18-D238/397E;mK18-null mice in response to MLR treatment was reduced compared with the control mouse strain. The lesser rate of apoptosis in K18-D238/397E;mK18-null livers is associated with delayed degradation and, thus, sustained activation of cell-survival-related protein kinases, including stress-activated protein kinases and the NF-κB transcription factor, up to 6-8 h after administration of anti-FasAb. However, activation of the kinases and NF-κB in K18-WT-reconstituted livers decreases dramatically 8 h after anti-FasAb administration. In addition, the D238/397E double-mutation results in prolonged stability of K18 protein in transfected cells and transgenic livers. Therefore, our results show that the caspase digestion-resistant K18 helps to maintain keratin filament organization and delays apoptosis, thereby resulting in protection from liver injury.
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Affiliation(s)
- Han-Na Yoon
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
| | - Sung-Yeon Yoon
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
| | - Jin-Hyuck Hong
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
| | - Nam-On Ku
- Department of Integrated OMICS for Biomedical Science, WCU Program of Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
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Consequences of Keratin Phosphorylation for Cytoskeletal Organization and Epithelial Functions. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 330:171-225. [DOI: 10.1016/bs.ircmb.2016.09.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Salas PJ, Forteza R, Mashukova A. Multiple roles for keratin intermediate filaments in the regulation of epithelial barrier function and apico-basal polarity. Tissue Barriers 2016; 4:e1178368. [PMID: 27583190 PMCID: PMC4993576 DOI: 10.1080/21688370.2016.1178368] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/05/2016] [Accepted: 04/07/2016] [Indexed: 12/27/2022] Open
Abstract
As multicellular organisms evolved a family of cytoskeletal proteins, the keratins (types I and II) expressed in epithelial cells diversified in more than 20 genes in vertebrates. There is no question that keratin filaments confer mechanical stiffness to cells. However, such a number of genes can hardly be explained by evolutionary advantages in mechanical features. The use of transgenic mouse models has revealed unexpected functional relationships between keratin intermediate filaments and intracellular signaling. Accordingly, loss of keratins or mutations in keratins that cause or predispose to human diseases, result in increased sensitivity to apoptosis, regulation of innate immunity, permeabilization of tight junctions, and mistargeting of apical proteins in different epithelia. Precise mechanistic explanations for these phenomena are still lacking. However, immobilization of membrane or cytoplasmic proteins, including chaperones, on intermediate filaments (“scaffolding”) appear as common molecular mechanisms and may explain the need for so many different keratin genes in vertebrates.
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Affiliation(s)
- Pedro J Salas
- Department of Cell Biology, Miller School of Medicine, University of Miami , Miami, FL, USA
| | - Radia Forteza
- Department of Cell Biology, Miller School of Medicine, University of Miami , Miami, FL, USA
| | - Anastasia Mashukova
- Department of Cell Biology, Miller School of Medicine, University of Miami, Miami, FL, USA; Department of Physiology, Nova Southeastern University, Fort Lauderdale, FL, USA
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Le Henaff C, Faria Da Cunha M, Hatton A, Tondelier D, Marty C, Collet C, Zarka M, Geoffroy V, Zatloukal K, Laplantine E, Edelman A, Sermet-Gaudelus I, Marie PJ. Genetic deletion of keratin 8 corrects the altered bone formation and osteopenia in a mouse model of cystic fibrosis. Hum Mol Genet 2016; 25:1281-93. [PMID: 26769674 DOI: 10.1093/hmg/ddw009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/06/2016] [Indexed: 12/23/2022] Open
Abstract
Patients with cystic fibrosis (CF) display low bone mass and alterations in bone formation. Mice carrying the F508del genetic mutation in the cystic fibrosis conductance regulator (Cftr) gene display reduced bone formation and decreased bone mass. However, the underlying molecular mechanisms leading to these skeletal defects are unknown, which precludes the development of an efficient anti-osteoporotic therapeutic strategy. Here we report a key role for the intermediate filament protein keratin 8 (Krt8), in the osteoblast dysfunctions in F508del-Cftr mice. We found that murine and human osteoblasts express Cftr and Krt8 at low levels. Genetic studies showed that Krt8 deletion (Krt8(-/-)) in F508del-Cftr mice increased the levels of circulating markers of bone formation, corrected the expression of osteoblast phenotypic genes, promoted trabecular bone formation and improved bone mass and microarchitecture. Mechanistically, Krt8 deletion in F508del-Cftr mice corrected overactive NF-κB signaling and decreased Wnt-β-catenin signaling induced by the F508del-Cftr mutation in osteoblasts. In vitro, treatment with compound 407, which specifically disrupts the Krt8-F508del-Cftr interaction in epithelial cells, corrected the abnormal NF-κB and Wnt-β-catenin signaling and the altered phenotypic gene expression in F508del-Cftr osteoblasts. In vivo, short-term treatment with 407 corrected the altered Wnt-β-catenin signaling and bone formation in F508del-Cftr mice. Collectively, the results show that genetic or pharmacologic targeting of Krt8 leads to correction of osteoblast dysfunctions, altered bone formation and osteopenia in F508del-Cftr mice, providing a therapeutic strategy targeting the Krt8-F508del-CFTR interaction to correct the abnormal bone formation and bone loss in cystic fibrosis.
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Affiliation(s)
- Carole Le Henaff
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | | | - Aurélie Hatton
- INSERM U-1151, Team 2, University Paris Descartes, Paris, France
| | | | - Caroline Marty
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Corinne Collet
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Mylène Zarka
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Valérie Geoffroy
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Kurt Zatloukal
- Institute of Pathology, Medical University of Graz, Graz, Austria and
| | - Emmanuel Laplantine
- Laboratoire de Signalisation et Pathogenèse, Institut Pasteur, Paris, France
| | | | | | - Pierre J Marie
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France,
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Roux A, Gilbert S, Loranger A, Marceau N. Impact of keratin intermediate filaments on insulin-mediated glucose metabolism regulation in the liver and disease association. FASEB J 2015; 30:491-502. [PMID: 26467793 DOI: 10.1096/fj.15-277905] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/21/2015] [Indexed: 12/17/2022]
Abstract
In all cells, a tight regulation exists between glucose uptake and utilization to prevent diseases related to its perturbed metabolism. In insulin-targeted cells, such as hepatocytes, proper glucose utilization requires an elaborate interplay between the insulin receptor, the glucose transporter, and mitochondria that involves the participation of actin microfilaments and microtubules. In addition, there is increasing evidence of an involvement of the third cytoskeletal network provided by intermediate filaments (IFs). Keratins belong to the multigene family of IF proteins, coordinately expressed as distinct pairs within the context of epithelial cell differentiation. Hepatocyte IFs are made up of the [keratin (K)8/K18] pair only, whereas pancreatic β-cell IFs additionally include small amounts of K7. There are accumulating examples of K8/K18 involvement in the glucose-insulin cross-talk, including the modulation of plasma glucose levels, insulin release from pancreatic β-cells, and insulin-mediated glucose uptake and glycogen production in hepatocytes after a K8/K18 loss. This review integrates the mechanistic features that support such an impact of K8/K18 IFs on insulin-dependent glucose metabolism regulation in liver and its implication in glucose- or insulin-associated diseases.
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Affiliation(s)
- Alexandra Roux
- Centre de Recherche sur le Cancer, Université Laval, and Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada
| | - Stéphane Gilbert
- Centre de Recherche sur le Cancer, Université Laval, and Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada
| | - Anne Loranger
- Centre de Recherche sur le Cancer, Université Laval, and Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada
| | - Normand Marceau
- Centre de Recherche sur le Cancer, Université Laval, and Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada
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Guldiken N, Zhou Q, Kucukoglu O, Rehm M, Levada K, Gross A, Kwan R, James LP, Trautwein C, Omary MB, Strnad P. Human keratin 8 variants promote mouse acetaminophen hepatotoxicity coupled with c-jun amino-terminal kinase activation and protein adduct formation. Hepatology 2015; 62:876-86. [PMID: 25963979 PMCID: PMC4549164 DOI: 10.1002/hep.27891] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 04/15/2015] [Accepted: 05/03/2015] [Indexed: 12/21/2022]
Abstract
UNLABELLED Keratins 8 and 18 (K8/K18) are the intermediate filaments proteins of simple-type digestive epithelia and provide important cytoprotective function. K8/K18 variants predispose humans to chronic liver disease progression and poor outcomes in acute acetaminophen (APAP)-related liver failure. Given that K8 G62C and R341H/R341C are common K8 variants in European and North American populations, we studied their biological significance using transgenic mice. Mice that overexpress the human K8 variants, R341H or R341C, were generated and used together with previously described mice that overexpress wild-type K8 or K8 G62C. Mice were injected with 600 mg/kg of APAP or underwent bile duct ligation (BDL). Livers were evaluated by microarray analysis, quantitative real-time polymerase chain reaction, immunoblotting, histological and immunological staining, and biochemical assays. Under basal conditions, the K8 G62C/R341H/R341C variant-expressing mice did not show an obvious liver phenotype or altered keratin filament distribution, whereas K8 G62C/R341C animals had aberrant disulphide cross-linked keratins. Animals carrying the K8 variants displayed limited gene expression changes, but had lower nicotinamide N-methyl transferase (NNMT) levels and were predisposed to APAP-induced hepatotoxicity. NNMT represents a novel K8/K18-associated protein that becomes up-regulated after K8/K18 transfection. The more pronounced liver damage was accompanied by increased and prolonged JNK activation; elevated APAP protein adducts; K8 hyperphosphorylation at S74/S432 with enhanced keratin solubility; and prominent pericentral keratin network disruption. No differences in APAP serum levels, glutathione, or adenosine triphosphate levels were noted. BDL resulted in similar liver injury and biliary fibrosis in all mouse genotypes. CONCLUSION Expression of human K8 variants G62C, R341H, or R341C in mice predisposes to acute APAP hepatotoxicity, thereby providing direct evidence for the importance of these variants in human acute liver failure.
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Affiliation(s)
- Nurdan Guldiken
- IZKF and Department of Internal Medicine III, University Hospital Aachen, Germany,Department of Internal Medicine I, University Hospital Ulm, Ulm Germany
| | - Qin Zhou
- Department of Medicine, Palo Alto VA Medical Center, CA; and Stanford University Digestive Disease Center, USA
| | - Ozlem Kucukoglu
- Department of Internal Medicine I, University Hospital Ulm, Ulm Germany
| | - Melanie Rehm
- Department of Internal Medicine I, University Hospital Ulm, Ulm Germany
| | - Kateryna Levada
- IZKF and Department of Internal Medicine III, University Hospital Aachen, Germany
| | - Annika Gross
- IZKF and Department of Internal Medicine III, University Hospital Aachen, Germany
| | - Raymond Kwan
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, and the VA Ann Arbor Health Care System, Ann Arbor, MI, USA
| | - Laura P. James
- Arkansas Children's Hospital Research Institute and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Christian Trautwein
- IZKF and Department of Internal Medicine III, University Hospital Aachen, Germany
| | - M. Bishr Omary
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, and the VA Ann Arbor Health Care System, Ann Arbor, MI, USA
| | - Pavel Strnad
- IZKF and Department of Internal Medicine III, University Hospital Aachen, Germany,Department of Internal Medicine I, University Hospital Ulm, Ulm Germany,To whom correspondence should be addressed. Corresponding author: Pavel Strnad, Department of Internal Medicine III and IZKF, University Hospital Aachen, Pauwelsstraße 30, D-52074 Aachen, Tel.: +49(241) 80-35324, Fax: +49(241) 80-82455,
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Lipid rafts and raft-mediated supramolecular entities in the regulation of CD95 death receptor apoptotic signaling. Apoptosis 2015; 20:584-606. [DOI: 10.1007/s10495-015-1104-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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