Cholesterol Depletion Alters Cardiomyocyte Subcellular Signaling and Increases Contractility.
Cholesterol Depletion Alters Cardiomyocyte Subcellular Signaling and Increases Contractility.
复制标题
胆固醇耗竭会改变心肌细胞亚细胞信号传导并增加收缩力。
DOI：
10.1371/journal.pone.0154151
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Lasley RD
中科院分区：
文献类型：
--
作者：
Haque MZ;McIntosh VJ;Abou Samra AB;Mohammad RM;Lasley RD
膜胆固醇水平在调节细胞功能中起重要作用。肌膜胆固醇集中在脂筏和小窝中，它们是质膜的烧瓶状内陷。支架蛋白小窝蛋白允许胆固醇在小窝中富集，并且小窝蛋白与许多蛋白质的相互作用调节它们的功能。本研究的目的是确定心肌细胞胆固醇水平的急性降低是否会改变亚细胞蛋白激酶活化、细胞内Ca 2+和收缩力。研究方法：从成年Sprague道利大鼠分离的心室肌细胞用胆固醇降低剂甲基-β-环糊精（MβCD，5 mM，1 h，室温）处理。评估总细胞胆固醇水平、小窝蛋白-3定位、亚细胞、ERK和p38丝裂原活化蛋白激酶（MAPK）信号传导、收缩性和[Ca 2 +]i。结果如下：用MβCD处理使胆固醇水平降低约45，并将小窝蛋白-3从细胞骨架和triton不溶性部分转移到triton可溶性部分，并增加细胞骨架、细胞溶质、triton可溶性和triton不溶性膜部分中ERK亚型的磷酸化，而不改变其亚细胞分布。而MβCD主要作用于p38α的亚细胞分布，对p38磷酸化影响不大。胆固醇耗竭增加心肌细胞收缩幅度和缩短率和舒张率，同时增加舒张期和收缩期[Ca 2 +]i。结论：这些结果表明，膜胆固醇水平的急性降低差异调节基底心肌细胞亚细胞MAPK信号传导，以及增加[Ca 2 +]i和收缩性。
Membrane cholesterol levels play an important factor in regulating cell function. Sarcolemmal cholesterol is concentrated in lipid rafts and caveolae, which are flask-shaped invaginations of the plasma membrane. The scaffolding protein caveolin permits the enrichment of cholesterol in caveolae, and caveolin interactions with numerous proteins regulate their function. The purpose of this study was to determine whether acute reductions in cardiomyocyte cholesterol levels alter subcellular protein kinase activation, intracellular Ca2+ and contractility. Methods: Ventricular myocytes, isolated from adult Sprague Dawley rats, were treated with the cholesterol reducing agent methyl-β-cyclodextrin (MβCD, 5 mM, 1 hr, room temperature). Total cellular cholesterol levels, caveolin-3 localization, subcellular, ERK and p38 mitogen activated protein kinase (MAPK) signaling, contractility, and [Ca2+]i were assessed. Results: Treatment with MβCD reduced cholesterol levels by ~45 and shifted caveolin-3 from cytoskeleton and triton-insoluble fractions to the triton-soluble fraction, and increased ERK isoform phosphorylation in cytoskeletal, cytosolic, triton-soluble and triton-insoluble membrane fractions without altering their subcellular distributions. In contrast the primary effect of MβCD was on p38 subcellular distribution of p38α with little effect on p38 phosphorylation. Cholesterol depletion increased cardiomyocyte twitch amplitude and the rates of shortening and relaxation in conjunction with increased diastolic and systolic [Ca2+]i. Conclusions: These results indicate that acute reductions in membrane cholesterol levels differentially modulate basal cardiomyocyte subcellular MAPK signaling, as well as increasing [Ca2+]i and contractility.