Slow‐twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain

Abstract

Myosin light chain 2 (MYL2) gene encodes the myosin regulatory light chain (RLC) simultaneously in heart ventricles and in slow‐twitch skeletal muscle. Using transgenic mice with cardiac‐specific expression of the human R58Q‐RLC mutant, we sought to determine whether the hypertrophic cardiomyopathy phenotype observed in papillary muscles (PMs) of R58Q mice is also manifested in slow‐twitch soleus (SOL) muscles. Skinned SOL muscles and ventricular PMs of R58Q animals exhibited lower contractile force that was not observed in the fast‐twitch extensor digitorum longus muscles of R58Q vs. wild‐type‐RLC mice, but mutant animals did not display gross muscle weakness in vivo. Consistent with SOL muscle abnormalities in R58Q vs. wild‐type mice, myosin ATPase staining revealed a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles. The similarities between SOL muscles and PMs of R58Q mice were further supported by quantitative proteomics. Differential regulation of proteins involved in energy metabolism, cell‐cell interactions, and protein‐protein signaling was concurrently observed in the hearts and SOL muscles of R58Q mice. In summary, even though R58Q expression was restricted to the heart of mice, functional similarities were clearly observed between the hearts and slow‐twitch skeletal muscle, suggesting that MYL2 mutated models of hypertrophic cardiomyopathy may be useful research tools to study the molecular, structural, and energetic mechanisms of cardioskeletal myopathy associated with myosin RLC.—Kazmierczak, K., Liang, J., Yuan, C.‐C, Yadav, S., Sitbon, Y. H., Walz, K., Ma, W., Irving, T. C., Cheah, J. X., Gomes, A. V., Szczesna‐Cordary, D. Slow‐twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain. FASEB J. 33, 3152–3166 (2019). http://www.fasebj.org

Hereditary heart disease: pathophysiology, clinical presentation, and animal models of HCM, RCM, and DCM associated with mutations in cardiac myosin light chains

“…This coincided a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles, as well as in differential regulation of proteins between the heart and SOL muscles of R58Q mice. These data suggest that MYL2 models of HCM may be used as a model to study the molecular, structural, and energetic mechanisms of RLC mutation-induced cardioskeletal myopathy 61 . Huang et al described a novel Asp94Ala (D94A) DCM mutation in MYL2 (Fig.…”

“…The study concluded that S15D-phosphomimic can be used as a potential rescue strategy to abrogate/alleviate the RLC mutation-induced phenotypes 131 . Interestingly, it was recently shown that R58Q-mutant mice showed functional similarities between the cardiac papillary muscles and slow-twitch soleus skeletal muscle, as evident by lower contractile force in both papillary and soleus muscles compared to fast-twitch extensor digitorum longus muscles of R58Q vs. wild-type-RLC mice 61 . This coincided a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles, as well as in differential regulation of proteins between the heart and SOL muscles of R58Q mice.…”

Using the SpyTag SpyCatcher system to label smooth muscle myosin II filaments with a quantum dot on the regulatory light chain

“…Other important functions of myosin II are attributed to the RLC such as, folding to the 10S conformation (Trybus & Lowey, ), stiffness of the lever arm (Matthew, Khromov, Trybus, Somlyo, & Somlyo, ), coupling of ATPase and motility (Trybus, Waller, & Chatman, ), and intermolecular interactions in the dephosphorylated state (Liu, Shu, Hong, Levine, & Korn, ; Ni et al, ; Wendt, Taylor, Trybus, & Taylor, ). It is therefore not surprising that modifications throughout the RLC sequence can affect myosin function in general (Ikebe et al, ; Ikebe, Reardon, Mitsui, & Ikebe, ; Kambara et al, ; Kazmierczak et al, ; Ni et al, ; Ni et al, ; Rowe & Kendrick‐Jones, ; Rowe & Kendrick‐Jones, ; Sweeney, Yang, Zhi, Stull, & Trybus, ; Szczesna et al, ; Trybus & Chatman, ).…”

“…Shu, Hong, Levine, & Korn, 2006;Ni et al, 2012;Wendt, Taylor, Trybus, & Taylor, 2001). It is therefore not surprising that modifications throughout the RLC sequence can affect myosin function in general (Ikebe et al, 1994;Ikebe, Reardon, Mitsui, & Ikebe, 1999;Kambara et al, 1999;Kazmierczak et al, 2019;Ni et al, 2009;Ni et al, 2012;Rowe & Kendrick-Jones, 1992;Rowe & Kendrick-Jones, 1993;Sweeney, Yang, Zhi, Stull, & Trybus, 1994;Szczesna et al, 2001;Trybus & Chatman, 1993).…”

“…The smooth muscle RLC has a single native cysteine residue (C108) that can be labeled with small extrinsic probes without a large effect on myosin function. Importantly, the RLC can be exchanged with good efficiency into many types of muscle fibers (Allen, Ling, Irving, & Goldman, 1996;Gollub et al, 1999;Kazmierczak et al, 2019). GFP-tagged RLC has been used to study the localization and mechanics of myosin in cells (Beach, Licate, Crish, & Egelhoff, 2011;Komatsu, Yano, Shibata, Tuft, & Ikebe, 2000;Peterson et al, 2004), as well as the mechanical properties of NMM expressed in insect cells (Melli et al, 2018;Nagy et al, 2013).…”