1. Cardiomyocyte contractile impairment in heart failure results from reduced BAG3-mediated sarcomeric protein turnover.
- Author
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Martin TG, Myers VD, Dubey P, Dubey S, Perez E, Moravec CS, Willis MS, Feldman AM, and Kirk JA
- Subjects
- Adaptor Proteins, Signal Transducing deficiency, Adaptor Proteins, Signal Transducing genetics, Adult, Aged, Animals, Apoptosis Regulatory Proteins deficiency, Apoptosis Regulatory Proteins genetics, Disease Models, Animal, Female, Genetic Therapy, Heart Failure genetics, Heart Failure therapy, Humans, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Middle Aged, Muscle Proteins metabolism, Myocardial Contraction genetics, Myocardial Contraction physiology, Myocytes, Cardiac metabolism, Rats, Rats, Sprague-Dawley, Recombinant Proteins genetics, Recombinant Proteins metabolism, Sarcomeres metabolism, Adaptor Proteins, Signal Transducing metabolism, Apoptosis Regulatory Proteins metabolism, Heart Failure physiopathology, Myocytes, Cardiac physiology
- Abstract
The association between reduced myofilament force-generating capacity (F
max ) and heart failure (HF) is clear, however the underlying molecular mechanisms are poorly understood. Here, we show impaired Fmax arises from reduced BAG3-mediated sarcomere turnover. Myofilament BAG3 expression decreases in human HF and positively correlates with Fmax . We confirm this relationship using BAG3 haploinsufficient mice, which display reduced Fmax and increased myofilament ubiquitination, suggesting impaired protein turnover. We show cardiac BAG3 operates via chaperone-assisted selective autophagy (CASA), conserved from skeletal muscle, and confirm sarcomeric CASA complex localization is BAG3/proteotoxic stress-dependent. Using mass spectrometry, we characterize the myofilament CASA interactome in the human heart and identify eight clients of BAG3-mediated turnover. To determine if increasing BAG3 expression in HF can restore sarcomere proteostasis/Fmax , HF mice were treated with rAAV9-BAG3. Gene therapy fully rescued Fmax and CASA protein turnover after four weeks. Our findings indicate BAG3-mediated sarcomere turnover is fundamental for myofilament functional maintenance.- Published
- 2021
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