Abstract 12653: Ubiquitin E3 Ligase ITCH Ameliorates Reactive Oxygen Species-Induced Cardiotoxicity through Interacting with Thioredoxin-Interacting Protein
Background: Ubiquitin E3 ligase ITCH is an enzyme which plays a pivotal role in posttranslational modification by ubiquitin proteasomal protein degradation. Thioredoxin-interacting protein (TXNIP) is a negative regulator of thioredoxin, which is an endogenous reactive oxygen species (ROS) scavenger. We focused on functional role of ubiquitin E3 ligase ITCH and its interaction with TXNIP to elucidate the mechanism of ROS-induced cardiotoxicity, such as doxorubicin (Dox) and H2O2.
Methods and Results: We confirmed both protein and mRNA expression of ITCH in neonatal rat cardiomyocyte.
Immunoprecipitation showed protein interaction between TXNIP and ITCH in cardiomyocyte.
Overexpression of ITCH increased proteasomal TXNIP degradation and augmented thioredoxin activity, which led to inhibit cardiomyocyte apoptosis in ROS-induced cardiotoxicity. Conversely, knockdown of ITCH by siRNA inhibited TXNIP degradation and demonstrated a subsequent increase in cardiomyocyte apoptosis. Next, we generated cardiac-specific overexpression of ITCH transgenic mouse (ITCH-Tg mice). ITCH-Tg mice had significantly lower expression of TXNIP than wild type littermates in heart. Compared with wild type littermates, ITCH-Tg mice was inhibited an apoptosis in cardiac cells and restored cardiac dysfunction after Dox injection. Kaplan-Meier analysis revealed that ITCH-Tg mice had higher survival rate than wild type littermates after Dox injection.
Conclusion: We demonstrated for the first time that ITCH targets TXNIP for ubiquitin proteasome degradation and ameliorates ROS-induced cardiotoxicity by increasing thioredoxin activity in vitro and in vivo.
- © 2013 by American Heart Association, Inc.