Go to The Journal of Clinical Investigation
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Transfers
  • Advertising
  • Job board
  • Contact
  • Current issue
  • Past issues
  • By specialty
    • COVID-19
    • Cardiology
    • Immunology
    • Metabolism
    • Nephrology
    • Oncology
    • Pulmonology
    • All ...
  • Videos
  • Collections
    • Resource and Technical Advances
    • Clinical Medicine
    • Reviews
    • Editorials
    • Perspectives
    • Top read articles
  • JCI This Month
    • Current issue
    • Past issues

  • Current issue
  • Past issues
  • Specialties
  • In-Press Preview
  • Concise Communication
  • Editorials
  • Viewpoint
  • Top read articles
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Transfers
  • Advertising
  • Job board
  • Contact
HSC70 is a chaperone for wild-type and mutant cardiac myosin binding protein C
Amelia A. Glazier, … , Adam S. Helms, Sharlene M. Day
Amelia A. Glazier, … , Adam S. Helms, Sharlene M. Day
Published June 7, 2018
Citation Information: JCI Insight. 2018;3(11):e99319. https://doi.org/10.1172/jci.insight.99319.
View: Text | PDF
Research Article Cardiology Muscle biology

HSC70 is a chaperone for wild-type and mutant cardiac myosin binding protein C

  • Text
  • PDF
Abstract

Cardiac myosin binding protein C (MYBPC3) is the most commonly mutated gene associated with hypertrophic cardiomyopathy (HCM). Haploinsufficiency of full-length MYBPC3 and disruption of proteostasis have both been proposed as central to HCM disease pathogenesis. Discriminating the relative contributions of these 2 mechanisms requires fundamental knowledge of how turnover of WT and mutant MYBPC3 proteins is regulated. We expressed several disease-causing mutations in MYBPC3 in primary neonatal rat ventricular cardiomyocytes. In contrast to WT MYBPC3, mutant proteins showed reduced expression and failed to localize to the sarcomere. In an unbiased coimmunoprecipitation/mass spectrometry screen, we identified HSP70-family chaperones as interactors of both WT and mutant MYBPC3. Heat shock cognate 70 kDa (HSC70) was the most abundant chaperone interactor. Knockdown of HSC70 significantly slowed degradation of both WT and mutant MYBPC3, while pharmacologic activation of HSC70 and HSP70 accelerated degradation. HSC70 was expressed in discrete striations in the sarcomere. Expression of mutant MYBPC3 did not affect HSC70 localization, nor did it induce a protein folding stress response or ubiquitin proteasome dysfunction. Together these data suggest that WT and mutant MYBPC3 proteins are clients for HSC70, and that the HSC70 chaperone system plays a major role in regulating MYBPC3 protein turnover.

Authors

Amelia A. Glazier, Neha Hafeez, Dattatreya Mellacheruvu, Venkatesha Basrur, Alexey I. Nesvizhskii, Lap Man Lee, Hao Shao, Vi Tang, Jaime M. Yob, Jason E. Gestwicki, Adam S. Helms, Sharlene M. Day

×

Figure 5

Expression of MYBPC3 mutants does not significantly affect ubiquitin-proteasome function as assessed by the degron reporter GFPu.

Options: View larger image (or click on image) Download as PowerPoint
Expression of MYBPC3 mutants does not significantly affect ubiquitin-pro...
(A) Representative flow cytometry density plots. x axis, GFPu fluorescence; y axis, side scatter area (SSC-A). Data in the boxed area indicate GFP-positive cells. (B) Quantification of GFPu expression. Data are normalized to percentage GFPu-positive cells for control (untransduced) NRVMs. Mean ± SEM, n ≥ 11. Kruskal-Wallis 1-way ANOVA P < 0.0001. *P < 0.05 versus control by Dunn’s multiple-comparison test. (C) Representative Western blot of NRVMs expressing MYBPC3 constructs with and without treatment with 25 μM proteasome inhibitor lactacystin. Black line between lanes indicates noncontiguous samples from the same blot. Degradation of adenovirally expressed WT and mutant MYBPC3 is inhibited by lactacystin, while endogenous rat WT MYBPC3 levels were not significantly affected.

Copyright © 2022 American Society for Clinical Investigation
ISSN 2379-3708

Sign up for email alerts