title: HECT-Type Ubiquitin E3 Ligase ITCH Interacts With Thioredoxin-Interacting Protein and Ameliorates Reactive Oxygen Species-Induced Cardiotoxicity.
abstract: BACKGROUND
  The homologous to the E6-AP carboxyl terminus (HECT)-type ubiquitin E3 ligase ITCH is an enzyme that plays a pivotal role in posttranslational modification by ubiquitin proteasomal protein degradation. Thioredoxin-interacting protein (TXNIP) is a negative regulator of the thioredoxin system and an endogenous reactive oxygen species scavenger. In the present study, we focused on the functional role of ubiquitin E3 ligase ITCH and its interaction with TXNIP to elucidate the mechanism of cardiotoxicity induced by reactive oxygen species, such as doxorubicin and hydrogen peroxide.
  
  
  RESULTS
  Protein interaction between TXNIP and ITCH in cardiomyocyte was confirmed by immunoprecipitation assays. Overexpression of ITCH increased proteasomal TXNIP degradation and augmented thioredoxin activity, leading to inhibition of reactive oxygen species generation, p38 MAPK, p53, and subsequent intrinsic pathway cardiomyocyte apoptosis in reactive oxygen species-induced cardiotoxicity. Conversely, knockdown of ITCH using small interfering RNA inhibited TXNIP degradation and resulted in a subsequent increase in cardiomyocyte apoptosis. Next, we generated a transgenic mouse with cardiac-specific overexpression of ITCH, called the ITCH-Tg mouse. The expression level of TXNIP in the myocardium in ITCH-Tg mice was significantly lower than WT littermates. In ITCH-Tg mice, cardiac dysfunction and remodeling were restored compared with WT littermates after doxorubicin injection and myocardial infarction surgery. Kaplan-Meier analysis revealed that ITCH-Tg mice had a higher survival rate than WT littermates after doxorubicin injection and myocardial infarction surgery.
  
  
  CONCLUSIONS
  We demonstrated, for the first time, that ITCH targets TXNIP for ubiquitin-proteasome degradation in cardiomyocytes and ameliorates reactive oxygen species-induced cardiotoxicity through the thioredoxin system.
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Otaki
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Tetsu
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Akira
authors.initials: A
authors.lastname: Funayama
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Netsu
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Yuki
authors.initials: Y
authors.lastname: Honda
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Taro
authors.initials: T
authors.lastname: Narumi
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Shinpei
authors.initials: S
authors.lastname: Kadowaki
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Shintaro
authors.initials: S
authors.lastname: Honda
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Takanori
authors.initials: T
authors.lastname: Arimoto
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Shishido
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Takuya
authors.initials: T
authors.lastname: Miyamoto
authors.affiliation: Laboratory of Biomedical Chemistry, Department of Molecular Medical Science, Graduate School of Medicine, University of Hiroshima, Japan (H.K.).
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kamata
authors.affiliation: Research Laboratory for Molecular Genetics, Yamagata University School of Medicine, Yamagata, Japan (O.N.).
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakajima
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan (Y.O., H.T., T.W., A.F., S.N., Y.H., T.N., S.K., H.H., S.H., T.A., T.S., T.M., I.K.).
authors.forename: Isao
authors.initials: I
authors.lastname: Kubota
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D009202:Cardiomyopathies / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D066126:Cardiotoxicity; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004317:Doxorubicin; D008822:Mice, Transgenic; D009203:Myocardial Infarction / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D059748:Proteolysis; D034622:RNA Interference; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C000611465:Itch protein, rat; D017382:Reactive Oxygen Species; C493796:TXNIP protein, rat; D016159:Tumor Suppressor Protein p53; C445672:Txnip protein, mouse; D013879:Thioredoxins; D004317:Doxorubicin; C471637:Itch protein, mouse; D044767:Ubiquitin-Protein Ligases; D048051:p38 Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex
keywords: ITCH; thioredoxin‐interacting protein; ubiquitin proteasome system