Open AccessHECT ‐Type Ubiquitin E3 Ligase ITCH Interacts With Thioredoxin‐Interacting Protein and Ameliorates Reactive Oxygen Species–Induced Cardiotoxicity
Author(s) -
Otaki Yoichiro,
Takahashi Hiroki,
Watanabe Tetsu,
Funayama Akira,
Netsu Shunsuke,
Honda Yuki,
Narumi Taro,
Kadowaki Shinpei,
Hasegawa Hiromasa,
Honda Shintaro,
Arimoto Takanori,
Shishido Tetsuro,
Miyamoto Takuya,
Kamata Hideaki,
Nakajima Osamu,
Kubota Isao
Publication year - 2016
Publication title -
journal of the american heart association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.494
H-Index - 85
ISSN - 2047-9980
DOI - 10.1161/jaha.115.002485
Subject(s) - txnip , thioredoxin interacting protein , ubiquitin ligase , reactive oxygen species , medicine , ubiquitin , protein degradation , apoptosis , thioredoxin , cancer research , microbiology and biotechnology , pharmacology , oxidative stress , biochemistry , biology , gene
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. Methods and 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. Conclusion 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.