Loss of myocardial mass in a neonatal rat cardiomyocyte culture is studied to determine whether there is a distinguishable cellular response based on the origin of mechano-signals. The approach herein compares the sarcomeric assembly and disassembly processes in heart cells by imposing mechano-signals at the interface with the extracellular matrix (extrinsic) and at the level of the myofilaments (intrinsic). Experiments compared the effects of imposed internal (inside/out) and external (outside/in) loading and unloading on modifications in neonatal rat cardiomyocytes. Unloading of the cellular substrate by myosin inhibition (1uM mavacamten), or cessation of cyclic strain (1 Hz, 10% strain) after preconditioning, led to significant disassembly of sarcomeric alpha-actinin by 6 hrs. In myosin inhibition, this was accompanied by redistribution of intracellular poly-ubiquitin K48 to the cellular periphery relative to the poly-ubiquitin K48 reservoir at the I-band. Moreover, loading and unloading of the cellular substrate led to a three-fold increase in post translational modifications (PTMs) when compared to the myosin-specific activation or inhibition. Specifically, phosphorylation increased with loading while ubiquitination increased with unloading, which may involve ERK1/2 and FAK activation. The identified PTMs, including ubiquitination, acetylation, and phosphorylation, are proposed to modify internal domains in alpha-actinin to increase its propensity to bind F-actin. These results demonstrate a link between mechanical feedback and sarcomere protein homeostasis via PTMs of alpha-actinin that exemplify how cardiomyocytes exhibit differential responses to the origin of force. The implications of sarcomere regulation governed by PTMs of alpha-actinin are discussed with respect to cardiac atrophy and heart failure.
[doi:10.25345/C56688V1G]
[dataset license: CC0 1.0 Universal (CC0 1.0)]
Keywords: HCM, HFrEF, sarcopenia, myotrope, calponin homology domain
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Principal Investigators: (in alphabetical order) |
Brenda Russell, University of Illinois at Chicago, USA |
| Submitting User: | cmwarren_8 |
Solís C, Warren CM, Dittloff K, DiNello E, Solaro RJ, Russell B.
Cardiomyocyte external mechanical unloading activates modifications of ?-actinin differently from sarcomere-originated unloading.
FEBS J. 2023 Nov;290(22):5322-5339. Epub 2023 Aug 17.
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