Cholesterol depletion impairs contractile machinery in neonatal rat cardiomyocytes

Abstract

Cholesterol regulates numerous cellular processes. Depleting its synthesis in skeletal myofibers induces vacuolization and contraction impairment. However, little is known about how cholesterol reduction affects cardiomyocyte behavior. Here, we deplete cholesterol by incubating neonatal cardiomyocytes with methyl-beta-cyclodextrin. Traction force microscopy shows that lowering cholesterol increases the rate of cell contraction and generates defects in cell relaxation. Cholesterol depletion also increases membrane tension, Ca2+ spikes frequency and intracellular Ca2+ concentration. These changes can be correlated with modifications in caveolin-3 and L-Type Ca2+ channel distributions across the sarcolemma. Channel regulation is also compromised since cAMP-dependent PKA activity is enhanced, increasing the probability of L-Type Ca2+ channel opening events. Immunofluorescence reveals that cholesterol depletion abrogates sarcomeric organization, changing spacing and alignment of α-actinin bands due to increase in proteolytic activity of calpain. We propose a mechanism in which cholesterol depletion triggers a signaling cascade, culminating with contraction impairment and myofibril disruption in cardiomyocytes.

Effect of testosterone supplementation on nitroso‐redox imbalance, cardiac metabolism markers, and S100 proteins expression in the heart of castrated male rats

“…Recently, Hissa et al . () have demonstrated that cholesterol depletion in neonatal rat cardiomyocytes impairs contraction and induces myofibril disruption. Likewise, Haque et al .…”

Modulation of Transient Receptor Potential C Channel Activity by Cholesterol

“…Cholesterol sequestration leads to dis-association of proteins from lipid rafts (Scheiffele et al, 1997;Kabouridis et al, 2000;Predescu et al, 2005) and to decrease in clustering of raft-associated molecules (Harder et al, 1998). Cholesterol depletion also disrupts caveolae structure; it does not result in the disappearance of caveolin but leads to a shift of caveolin from raft to non-raft fractions (Hissa et al, 2017) and to ruffling (Grimmer et al, 2002). It was shown that βCDs sequestered cholesterol from both cholesterol-rich and cholesterol-poor membrane domains (Ottico et al, 2003;Gaus et al, 2005;Rouquette-Jazdanian et al, 2006;Tikku et al, 2007).…”

Role of Membrane Cholesterol in Modulating Actin Architecture and Cellular Contractility

“…These combined techniques provide information of the diffusion coefficient of particles in the membrane and also reveal membrane corrals, barriers, and sites of confinement [38]. Finally, other optical techniques have been used to elucidate other features of lipid rafts: fluorescence correlation spectroscopy, to gain information of fluorophore mobility in the membrane [39]; fluorescence resonance energy transfer, to detect when fluorophores are in close proximity [40], and optical tweezers, to give information about the membrane mechanical parameters [8,41]. In the future, it is expected that other super-resolution microscopy techniques, such as stimulated emission depletion microscopy [42] or various forms of structured illumination microscopy may overcome the problems imposed by the diffraction limit.…”

“…Changes in membrane composition, particularly in cholesterol content, have also been shown to influence cell surface tension. MβCD causes an increase in tension in embryonic kidney cells [98], fibroblasts [9] and cardiomyocytes [99]. This increase is not only due to changes in membrane composition, but it also affects the actomyosin cytoskeleton.…”

“…Differences in muscle versus nonmuscle cell contractile behavior are observed upon cholesterol depletion using cyclodextrins. Muscle cells get impairment in their contractile machinery [8] whereas nonmuscle cells get more contractile [9]. This book chapter gives an overview about how cholesterol is organized at the plasma membrane and how its depletion changes cellular contractile properties.…”