title: 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.
authors.affiliation: James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States.
authors.forename: Barbara
authors.initials: B
authors.lastname: Hissa
authors.affiliation: James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Oakes
authors.affiliation: LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pontes
authors.affiliation: James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States.
authors.forename: Guillermina
authors.initials: G
authors.lastname: Ramírez-San Juan
authors.affiliation: James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Gardel
mesh_terms: D000185:Actinin / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D051244:Caveolin 3 / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000172:deficiency / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D017208:Rats, Wistar; D012508:Sarcolemma / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D047392:beta-Cyclodextrins / Q000378:metabolism / Q000494:pharmacology
chemical_list: D020746:Calcium Channels, L-Type; C495549:Cav3 protein, rat; D051244:Caveolin 3; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D000185:Actinin; D002784:Cholesterol; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium