title: ASK1 associates with troponin T and induces troponin T phosphorylation and contractile dysfunction in cardiomyocytes.
abstract: There is increasing support for the idea that excessive production of proinflammatory mediators such as tumor necrosis factor (TNF) and reactive oxygen species (ROS) contribute to the pathogenesis of cardiac dysfunction. However, the mechanisms by which cytokine/ROS production mediates cardiac dysfunction have not been established. Given that apoptosis signal-regulating kinase 1 (ASK1) is highly expressed in cardiac muscle and that ASK1 is an important mediator in the signaling pathways induced by tumor necrosis factor, interleukin-1, and ROS, we used the yeast two-hybrid system with ASK1 as bait to identify ASK1 substrates from a human heart cDNA library. The cDNA encoding the cardiac troponin T (cTnT) was isolated. ASK1 specifically interacted with cTnT, but not cTnI, in vitro and in vivo via the C-terminal ASK1 domain. ASK1 specifically phosphorylated cTnT in vitro and in vivo. Mutations in cTnT (T194/S198) at an ASK1-phosphorylation consensus sequence significantly reduced phosphorylation by ASK1. ROS-induced ASK1 activation, cTnT phosphorylation, and contractile dysfunction in cardiomyocytes showed similar kinetics. Moreover, overexpression of constitutively active ASK1 induces cTnT phosphorylation and inhibits shortening and calcium transient in adult cardiomyocytes. We conclude that ASK1 plays an important role in regulation of cardiac contractile function by phosphorylating cTnT and may participate in cytokine/ROS-induced pathogenesis of cardiomyopathy and heart failure.
authors.affiliation: Center for Cardiovascular Research, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Xiangrong
authors.initials: X
authors.lastname: He
authors.forename: Yingmei
authors.initials: Y
authors.lastname: Liu
authors.forename: Virendra
authors.initials: V
authors.lastname: Sharma
authors.forename: Robert T
authors.initials: RT
authors.lastname: Dirksen
authors.forename: Richard
authors.initials: R
authors.lastname: Waugh
authors.forename: Shey-Shing
authors.initials: SS
authors.lastname: Sheu
authors.forename: Wang
authors.initials: W
authors.lastname: Min
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004789:Enzyme Activation; D015723:Gene Library; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D020107:Troponin T / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D020107:Troponin T; D006861:Hydrogen Peroxide; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C482858:MAP3K5 protein, human