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Cells need intracellular forces for their physiological functions, such as migration, cytokinesis, and morphogenesis. The actin cytoskeleton generates a large fraction of the forces via interactions between cytoskeletal components, such as actin filament (F-actin), myosin, and actin cross-linking proteins. Myosin II plays the most important role in cellular force generation. Myosin II molecules self-assemble into filaments with different structures depending on myosin II isoforms and other conditions such as pH and ionic concentration. It has remained elusive how force generation in actomyosin structures is affected by the architecture of myosin II filaments. In this study, we employed an agent-based model to investigate the effects of the structural properties of myosin II filaments on force generation in disorganized actomyosin structures. We demonstrated that the magnitude of forces and the efficiency of force generation can vary over a wide range depending on the number and spatial distribution of myosin II filaments. Further, we showed that the number of myosin heads and the length of a bare zone at the center of myosin II filaments without heads highly affect the force generation process in bundles and networks. Our study provides insights into understanding the roles of the structural properties of myosin II filaments in actomyosin contractility.
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http://dx.doi.org/10.7554/eLife.105236 | DOI Listing |
Am J Physiol Heart Circ Physiol
September 2025
Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri.
The sarcomeric protein cardiac myosin binding protein-C (cMyBP-C) binds myosin on thick filaments and regulates cardiac myocyte contraction. Our lab has reported that permeabilized cardiac myocytes lacking cMyBP-C generate greater power and show disproportionately fast sarcomere shortening velocities at high loads. Also, high resolution X-ray diffraction of cardiac trabeculae found that myosin cross-bridges in the cMyBP-C zone are the most active during loaded contractions.
View Article and Find Full Text PDFJ Proteome Res
September 2025
State Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Shell matrix proteins (SMPs) are fundamental biological macromolecules for mollusk shell formation, yet fewer than 400 SMPs in mollusks have been previously identified, hindering our understanding of how mollusks construct and maintain their shells. Here, we identified 1689 SMPs in the Pacific oyster using three different mass spectrometry techniques, representing a significant methodological advancement in shell proteomics, enabling a 6.52-fold increase in SMP identification compared to previous studies.
View Article and Find Full Text PDFBiophys Rep (N Y)
September 2025
Cellular Signal Transduction in the Cardiovascular System COBRE, University of Nevada Reno, Reno, NV 89557; Department of Nutrition, University of Nevada Reno, Reno, NV 89557. Electronic address:
Skeletal muscle alpha actin (ACTA1) is important for muscle contraction and relaxation, with historical studies focused on ACTA1 mutations in muscle dysfunction. Proteomics reports have consistently observed that actin, including ACTA1, is acetylated at multiple lysine sites. However, few reports have studied the effects of actin acetylation on cellular function, and fewer have examined ACTA1 acetylation on skeletal muscle function.
View Article and Find Full Text PDFThe exquisitely organized sarcomere, the unit of contraction of striated muscle, is a stable structure with slow turnover of its components. The myosin chaperone UNC-45 and its binding partners, Hsp90 and Hsp70, are required for the initial folding of the myosin head domain and the assembly of myosin into thick filaments. There is increasing evidence that the UNC-45 system has an important role during aging to preserve sarcomere organization.
View Article and Find Full Text PDFT cell activation is characterized by rapid reorganization of the actin cytoskeleton and cell spreading on the antigen presenting cell. The T cell nucleus occupies a large fraction of the cell volume, and its mechanical properties are likely to act as a key determinant of activation. However, the contribution of nuclear mechanics to T cell spreading and activation is not well understood.
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