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PLoS One. 2015 Oct 14;10(10):e0133994. doi: 10.1371/journal.pone.0133994. eCollection 2015.

Characterization of the Cardiac Overexpression of HSPB2 Reveals Mitochondrial and Myogenic Roles Supported by a Cardiac HspB2 Interactome.

Author information

1
Microbiology and Molecular Biology Department, Brigham Young University, Provo, UT, 84602, United States of America.
2
Laboratory of Cardiac Disease, Redox Signaling and Cell Regeneration, Division of Cardiology, University of Utah School of Medicine, Salt Lake City, UT, 84132, United States of America.
3
Laboratory of Cardiac Disease, Redox Signaling and Cell Regeneration, Division of Cardiology, University of Utah School of Medicine, Salt Lake City, UT, 84132, United States of America; Division of Cardiovascular Medicine, Dept. of Medicine, Medical College of Wisconsin, Milwaukee, WI, 53226, United States of America.
4
Program in Integrative Cardiac Metabolism, Center for Cardiovascular Research, University of Illinois at Chicago College of Medicine, Chicago, IL, 60612, United States of America.
5
Division of Cardiovascular Medicine, Dept. of Medicine, Medical College of Wisconsin, Milwaukee, WI, 53226, United States of America.
6
UCLA Departments of Physiology, Medicine, and Cardiology, Los Angeles, CA, 90095, United States of America.

Abstract

Small Heat Shock Proteins (sHSPs) are molecular chaperones that transiently interact with other proteins, thereby assisting with quality control of proper protein folding and/or degradation. They are also recruited to protect cells from a variety of stresses in response to extreme heat, heavy metals, and oxidative-reductive stress. Although ten human sHSPs have been identified, their likely diverse biological functions remain an enigma in health and disease, and much less is known about non-redundant roles in selective cells and tissues. Herein, we set out to comprehensively characterize the cardiac-restricted Heat Shock Protein B-2 (HspB2), which exhibited ischemic cardioprotection in transgenic overexpressing mice including reduced infarct size and maintenance of ATP levels. Global yeast two-hybrid analysis using HspB2 (bait) and a human cardiac library (prey) coupled with co-immunoprecipitation studies for mitochondrial target validation revealed the first HspB2 "cardiac interactome" to contain many myofibril and mitochondrial-binding partners consistent with the overexpression phenotype. This interactome has been submitted to the Biological General Repository for Interaction Datasets (BioGRID). A related sHSP chaperone HspB5 had only partially overlapping binding partners, supporting specificity of the interactome as well as non-redundant roles reported for these sHSPs. Evidence that the cardiac yeast two-hybrid HspB2 interactome targets resident mitochondrial client proteins is consistent with the role of HspB2 in maintaining ATP levels and suggests new chaperone-dependent functions for metabolic homeostasis. One of the HspB2 targets, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), has reported roles in HspB2 associated phenotypes including cardiac ATP production, mitochondrial function, and apoptosis, and was validated as a potential client protein of HspB2 through chaperone assays. From the clientele and phenotypes identified herein, it is tempting to speculate that small molecule activators of HspB2 might be deployed to mitigate mitochondrial related diseases such as cardiomyopathy and neurodegenerative disease.

PMID:
26465331
PMCID:
PMC4605610
DOI:
10.1371/journal.pone.0133994
[Indexed for MEDLINE]
Free PMC Article

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