https://phaidra.vetmeduni.ac.at/o:3199 Remodeling of skeletal muscle myosin metabolic states in hibernating mammals Lewis, Christopher T. A. Christopher T. A. Lewis 0000-0003-4477-422X University of Copenhagen Ochala, Julien Julien Ochala University of Copenhagen Sprenger, Ryan J. Ryan J. Sprenger University of British Columbia Drew, Kelly Kelly Drew University of Alaska Fairbanks Toien, Oivind Oivind Toien 0000-0001-5967-2483 University of Alaska Fairbanks Barnes, Brian Brian Barnes University of Alaska Fairbanks Fedorov, Vadim B. Vadim B. Fedorov University of Alaska Fairbanks Goropashnaya, Anna V. Anna V. Goropashnaya University of Alaska Fairbanks Staples, James F. James F. Staples University of Western Ontario Giroud, Sylvain Sylvain Giroud 0000-0001-6621-7462 University of Veterinary Medicine Vienna / Northern Michigan University Frobert, Ole Ole Frobert Aarhus University / Örebro University Amigo, Nuria Nuria Amigo Biosfer Teslab Merino, Carla Carla Merino Biosfer Teslab Kuehn, Michel N. Michel N. Kuehn University of Muenster / Accelerated Muscle Biotechnologies Consultants Hessel, Anthony L. Anthony L. Hessel University of Muenster / Accelerated Muscle Biotechnologies Consultants Iwamoto, Hiroyuki Hiroyuki Iwamoto Japan Synchrotron Radiation Research Institute Zhang, Changxin Changxin Zhang University of Michigan Gronset, Magnus Magnus Gronset University of Copenhagen Seaborne, Robert A. E. Robert A. E. Seaborne University of Copenhagen / King's College London Laitila, Jenni Jenni Laitila University of Copenhagen Olsen, Mathilde S. Mathilde S. Olsen University of Copenhagen Melhedegaard, Elise G. Elise G. Melhedegaard University of Copenhagen Ognjanovic, Marija M. Marija M. Ognjanovic University of Copenhagen eLife Sciences Publications Ltd text eng Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20 °C). Upon repeating loaded Mant-ATP chase experiments at 8 °C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77-107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis. Animals; Hibernation physiology; Energy Metabolism; Skeletal Muscle Myosinsmetabolism; Ursidaemetabolism physiology; Adenosine Triphosphate metabolism; Muscle, Skeletal metabolism physiology; Muscle Fibers, Skeletal metabolism; Proteomics http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:3199/download 10.7554/eLife.94616 https://phaidra.vetmeduni.ac.at/o:605 application/pdf eLife 13 (2024) eLife 13 3.88 MB 2024