TY - JOUR
T1 - Skeletal MyBP-C isoforms tune the molecular contractility of divergent skeletal muscle systems
AU - Li, Amy
AU - Nelson, Shane R.
AU - Rahmanseresht, Sheema
AU - Braet, Filip
AU - Cornachione, Anabelle S.
AU - Previs, Samantha Beck
AU - O’Leary, Thomas S.
AU - McNamara, James W.
AU - Rassier, Dilson E.
AU - Sadayappan, Sakthivel
AU - Previs, Michael J.
AU - Warshaw, David M.
N1 - Funding Information:
ACKNOWLEDGMENTS. We thank Ms. Nicole Bouffard (Microscopy Imaging Center, University of Vermont) and Mr. Todd Clason (Imaging/Physiology Core Facility, University of Vermont) for expert assistance in cryo-section and confocal imaging. We thank Guy Kennedy from the Instrumentation and Model Facility at the University of Vermont for his microscopy expertise. We also thank Prof. Doug Taatjes (University of Vermont) for proficient advice on immunolabeling. This work was supported by NIH Grants HL059408, AR067279, and HL126909 (to D.M.W.), HL130356, HL139680, AR067279, and HL105826 (to S.S.), and HL124041 (to M.J.P.); by American Heart Association Grants 19TPA34830084 and 19UFEL34380251 (to S.S.) and 17POST33630095 (to J.W.M.); and by the Natural Sciences and Engineering Research Council of Canada (to D.E.R.). D.E.R. is a Canada Research Chair (Tier I) in Muscle Biophysics; and supported in part by a generous gift to D.M.W. from Arnold and Mariel Goran.
Funding Information:
We thank Ms. Nicole Bouffard (Microscopy Imaging Center, University of Vermont) and Mr. Todd Clason (Imaging/Physiology Core Facility, University of Vermont) for expert assistance in cryo-section and confocal imaging. We thank Guy Kennedy from the Instrumentation and Model Facility at the University of Vermont for his microscopy expertise. We also thank Prof. Doug Taatjes (University of Vermont) for proficient advice on immunolabeling. This work was supported by NIH Grants HL059408, AR067279, and HL126909 (to D.M.W.), HL130356, HL139680, AR067279, and HL105826 (to S.S.), and HL124041 (to M.J.P.); by American Heart Association Grants 19TPA34830084 and 19UFEL34380251 (to S.S.) and 17POST33630095 (to J.W.M.); and by the Natural Sciences and Engineering Research Council of Canada (to D.E.R.). D.E.R. is a Canada Research Chair (Tier I) in Muscle Biophysics; and supported in part by a generous gift to D.M.W. from Arnold and Mariel Goran.
Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.
PY - 2019/10/22
Y1 - 2019/10/22
N2 - Skeletal muscle myosin-binding protein C (MyBP-C) is a myosin thick filament-associated protein, localized through its C terminus to distinct regions (C-zones) of the sarcomere. MyBP-C modulates muscle contractility, presumably through its N terminus extending from the thick filament and interacting with either the myosin head region and/or the actin thin filament. Two isoforms of MyBPC (fast- and slow-type) are expressed in a muscle type-specific manner. Are the expression, localization, and Ca2+-dependent modulatory capacities of these isoforms different in fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles derived from Sprague–Dawley rats? By mass spectrometry, 4 MyBP-C isoforms (1 fast-type MyBP-C and 3 N-terminally spliced slow-type MyBP-C) were expressed in EDL, but only the 3 slow-type MyBP-C isoforms in SOL. Using EDL and SOL native thick filaments in which the MyBP-C stoichiometry and localization are preserved, native thin filament sliding over these thick filaments showed that, only in the C-zone, MyBP-C Ca2+ sensitizes the thin filament and slows thin filament velocity. These modulatory properties depended on MyBP-C’s N terminus as N-terminal proteolysis attenuated MyBP-C’s functional capacities. To determine each MyBP-C isoform’s contribution to thin filament Ca2+ sensitization and slowing in the C-zone, we used a combination of in vitro motility assays using expressed recombinant N-terminal fragments and in silico mechanistic modeling. Our results suggest that each skeletal MyBP-C isoform’s N terminus is functionally distinct and has modulatory capacities that depend on the muscle type in which they are expressed, providing the potential for molecular tuning of skeletal muscle performance through differential MyBP-C expression.
AB - Skeletal muscle myosin-binding protein C (MyBP-C) is a myosin thick filament-associated protein, localized through its C terminus to distinct regions (C-zones) of the sarcomere. MyBP-C modulates muscle contractility, presumably through its N terminus extending from the thick filament and interacting with either the myosin head region and/or the actin thin filament. Two isoforms of MyBPC (fast- and slow-type) are expressed in a muscle type-specific manner. Are the expression, localization, and Ca2+-dependent modulatory capacities of these isoforms different in fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles derived from Sprague–Dawley rats? By mass spectrometry, 4 MyBP-C isoforms (1 fast-type MyBP-C and 3 N-terminally spliced slow-type MyBP-C) were expressed in EDL, but only the 3 slow-type MyBP-C isoforms in SOL. Using EDL and SOL native thick filaments in which the MyBP-C stoichiometry and localization are preserved, native thin filament sliding over these thick filaments showed that, only in the C-zone, MyBP-C Ca2+ sensitizes the thin filament and slows thin filament velocity. These modulatory properties depended on MyBP-C’s N terminus as N-terminal proteolysis attenuated MyBP-C’s functional capacities. To determine each MyBP-C isoform’s contribution to thin filament Ca2+ sensitization and slowing in the C-zone, we used a combination of in vitro motility assays using expressed recombinant N-terminal fragments and in silico mechanistic modeling. Our results suggest that each skeletal MyBP-C isoform’s N terminus is functionally distinct and has modulatory capacities that depend on the muscle type in which they are expressed, providing the potential for molecular tuning of skeletal muscle performance through differential MyBP-C expression.
KW - Calcium regulation
KW - In vitro motility
KW - Mass spectrometry
KW - Muscle contraction
KW - Myosin thick filament
UR - http://www.scopus.com/inward/record.url?scp=85073717957&partnerID=8YFLogxK
U2 - 10.1073/pnas.1910549116
DO - 10.1073/pnas.1910549116
M3 - Article
C2 - 31591218
AN - SCOPUS:85073717957
SN - 0027-8424
VL - 116
SP - 21882
EP - 21892
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 43
ER -