Bomechanical overload induces reactive oxygen species that may participate in a broad variety of cellular signaling cascades, and reactive oxygen species may mediate both hypertrophic and apoptotic pathways in cardiac myocytes. Thus, biomechanical regulation of redox balance may play a major role in the pathogenesis of cardiovascular disease. Normally, the cellular cytoplasmic environment is reduced, with many free sulfhydryl groups and relatively rare disulfides; the major ubiquitous reductase responsible for maintaining proteins in the reduced state is thioredoxin. Vitamin D3 Up-regulated Protein 1 (VDUP1) binds to thioredoxin and inhibits thioredoxin activity. Here we present preliminary data on the importance of thioredoxin in cardiomyocyte survival; furthermore, we show that gene transfer of VDUP1 sensitizes cardiac myocytes to oxidative stress-induced apoptosis. We also show that growth factor signaling requires, in some circumstances, elimination of VDUP1 in order to allow thioredoxin activity. Thus, compelling evidence has now emerged that VDUP1, an obscure orphan gene product only a few years ago, is a critical regulator of diverse signaling events due to its direct control of thioredoxin activity. In this proposal, we describe four hypothesis-driven Aims that will define the role of VDUP1 in cardiomyocyte physiology and pathophysiology in vitro and in vivo. We will use a combination of cellular, molecular, genetic engineering, and mouse physiology to address these Aims. Although these experiments are focused on the specific role of VDUP1, they have implications for diverse cellular events beyond cardiovascular disease due to the importance of thioredoxin as both a reactive oxygen species scavenging protein and as a mediator of signal transduction.
Aim 1. To explore the mechanisms by which VDUP1 regulates cardiomyocyte viability.
Aim 2. To explore the role of VDUP1/ thioredoxin in biomechanically-mediated hypertrophy in cardiac myocytes.
Aim 3. To define the role of transient VDUP1 or thioredoxin overexpression using gene transfer in cardiac myocytes under pathophysiologic stress in vivo.
Aim 4. To explore whether targeted VDUP1 gene deletion reveals a functional role for VDUP1 in left ventricular hypertrophy and remodeling.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL073809-03
Application #
7038296
Study Section
Cardiovascular and Renal Study Section (CVB)
Program Officer
Evans, Frank
Project Start
2004-04-01
Project End
2009-03-31
Budget Start
2006-04-01
Budget End
2007-03-31
Support Year
3
Fiscal Year
2006
Total Cost
$417,525
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
Yoshioka, Jun; Lee, Richard T (2008) Vascularization as a potential enemy in valvular heart disease. Circulation 118:1694-6
Chutkow, William A; Patwari, Parth; Yoshioka, Jun et al. (2008) Thioredoxin-interacting protein (Txnip) is a critical regulator of hepatic glucose production. J Biol Chem 283:2397-406
Yoshioka, Jun; Imahashi, Kenichi; Gabel, Scott A et al. (2007) Targeted deletion of thioredoxin-interacting protein regulates cardiac dysfunction in response to pressure overload. Circ Res 101:1328-38
Lammerding, Jan; Lee, Richard T (2007) Torn apart: membrane rupture in muscular dystrophies and associated cardiomyopathies. J Clin Invest 117:1749-52
Ji, Julie Y; Lee, Richard T; Vergnes, Laurent et al. (2007) Cell nuclei spin in the absence of lamin b1. J Biol Chem 282:20015-26
Patwari, Parth; Higgins, Luke J; Chutkow, William A et al. (2006) The interaction of thioredoxin with Txnip. Evidence for formation of a mixed disulfide by disulfide exchange. J Biol Chem 281:21884-91
Lammerding, Jan; Fong, Loren G; Ji, Julie Y et al. (2006) Lamins A and C but not lamin B1 regulate nuclear mechanics. J Biol Chem 281:25768-80