The highly ordered arrangement of sarcomeric myosin during striated muscle development requires spontaneous calcium (Ca(2+)) transients. Here, we show that blocking transients also compromises patterned assembly of actin thin filaments, titin, and capZ. Because a conserved temporal assembly pattern has been described for these proteins, selective inhibitors of either thick or thin filament formation were used to determine their relative temporal interdependencies. For example, inhibition of myosin light chain kinase (MLCK) by application of a specific inhibitory peptide or phorbol myistate acetate (PMA) disrupts myosin assembly without significantly affecting formation of actin bands. The MLCK inhibitor ML-7, however, disrupted actin as well as myosin. Surprisingly, agents that interfere with actin dynamics, such as cytochalasin D, produced only minor organizational disruptions in actin, capZ, and titin staining. However, cytochalasin D and other actin disrupting compounds significantly perturbed myosin organization. The results indicate that (1) Ca(2+) transients regulate one or more of the earliest steps in sarcomere formation, (2) mature actin filaments can assemble independently of myosin band formation, and (3) myosin thick filament assembly is extremely sensitive to disruption of either the actin or titin filament systems.
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http://dx.doi.org/10.1002/dvdy.10428 | DOI Listing |
Appl Biochem Biotechnol
January 2025
Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital Affiliated to Tianjin Medical University, No.154 Heping Road to Anshan, Tianjin City, 300052, People's Republic of China.
Dysregulated circular RNAs (circRNAs) has been revealed to be involved in pulmonary fibrosis progression. Herein, this study focused on exploring the function and mechanism of circRNA Zinc Finger MYM-Type Containing 2 (circZMYM2) on idiopathic pulmonary fibrosis (IPF) using transforming growth factor (TGF)-β1-stimulated fibroblasts. Human fibroblast cell lines IMR-90 and HFL1 were stimulated with TGF-β1 to mimic fibrosis condition in vitro.
View Article and Find Full Text PDFCurr Mol Pharmacol
January 2025
Department of Cardiology, Affiliated People's Hospital of Jiangsu University, Zhenjiang 212000, Jiangsu, China.
Aims: Cardiac fibrosis causes most pathological alterations of cardiomyopathy in diabetes and heart failure patients. The activation and transformation of cardiac fibroblasts (CFs) are the main pathological mechanisms of cardiac fibrosis. It has been established that Sirtuin1 (Sirt1) plays a protective role in the pathogenesis of cardiovascular disorders.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
Division of Hemostasis and Thrombosis, Department of Medicine, BIDMC, Harvard Medical School, Boston, MA, USA.
The actin cytoskeleton serves an important, but poorly characterized, role in controlling granule exocytosis. The dynamic nature of actin remodeling allows it to act both as a barrier to prevent indiscriminate granule release and as a facilitator of membrane fusion. In its capacity to promote exocytosis, filamentous actin binds to components of the exocytotic machinery through actin binding proteins, but also through direct interactions with SNAREs.
View Article and Find Full Text PDFNat Chem Biol
January 2025
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA.
Nucleoside triphosphate (NTP)-dependent protein assemblies such as microtubules and actin filaments have inspired the development of diverse chemically fueled molecular machines and active materials but their functional sophistication has yet to be matched by design. Given this challenge, we asked whether it is possible to transform a natural adenosine 5'-triphosphate (ATP)-dependent enzyme into a dissipative self-assembling system, thereby altering the structural and functional mode in which chemical energy is used. Here we report that FtsH (filamentous temperature-sensitive protease H), a hexameric ATPase involved in membrane protein degradation, can be readily engineered to form one-dimensional helical nanotubes.
View Article and Find Full Text PDFZhongguo Zhong Yao Za Zhi
December 2024
Key Laboratory of Orthopedics & Traumatology of Traditional Chinese Medicine and Rehabilitation, Ministry of Education Fuzhou 350122, China.
This study aims to explore the mechanism of Zhuanggu Jianxi Decoction in reducing synovial tissue inflammation in human knee osteoarthritis(KOA) via the liver X receptors(LXRs)/nuclear factor(NF)-κB signaling pathway. The synovial tissue samples were collected from 5 healthy volunteers and 30 KOA synovitis patients and cultured in vitro. The samples from the heathy volunteers were set as the normal group, and those from KOA synovitis patients were randomized into synovitis, Zhuanggu Jianxi Decoction, LXRα inhibitor, and N-CoR inhibitor groups.
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