Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia.
Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia.
Exp Gerontol. 2017 Sep;95:26-33. doi: 10.1016/j.exger.2017.05.009. Epub 2017 May 11.
Phosphorylation is a major post-translational modification of αB-crystallin (CryaB) and determines this protein's chaperone activity, intracellular distribution, translocation, and cytoprotective functions. Phosphorylation of CryaB manifests itself as either beneficial or deleterious consequences depending on the extent of phosphorylation and interaction with the cytoskeleton. Herein, for the first time, we compared the age-related alterations of the expression and phosphorylation (on Ser59: pS59) of CryaB in the myocardium of Wistar and senescence-accelerated OXYS rats. The latters, as we demonstrated here, develop cardiomyopathy by the age of 12 months against the background of hypertension. Rats at the age of 20 days, 3, 12, and 24 months were used. The expression of CryaB mRNA (studied by RT-PCR) and of the CryaB protein (analyzed by western blotting) increased with age in the myocardium of both Wistar and OXYS rats, but only at the age of 24 months did their levels become lower in OXYS rats. Phosphorylation of CryaB increased with age in all rats. There was no association of cardiomyopathy with the pS59-CryaB amount in the detergent-soluble fraction either. Moreover, immunostaining of the myocardium revealed that the amount of pS59-CryaB was greater in OXYS rats than in the control animals. This phenomenon was the result of translocation of pS59-CryaB from the detergent-soluble protein fraction to the detergent-insoluble one. The amount of pS59-CryaB in striated sarcomeres (detergent-insoluble) of the myocardium increased with age in both strains but faster in the myocardium of OXYS rats, and its accumulation preceded the development of cardiomyopathy. Translocation of phosphorylated CryaB to sarcomeres affects functional and structural properties (of cardiomyocytes) that are crucial for contractile function and myofibrillar organization and may be an important component of an endogenous mechanism of aging of the myocardium.
磷酸化是 αB-晶体蛋白（CryaB）的主要翻译后修饰，决定了该蛋白的伴侣活性、细胞内分布、易位和细胞保护功能。CryaB 的磷酸化表现为有益或有害的后果，具体取决于磷酸化程度和与细胞骨架的相互作用。在此，我们首次比较了 Wistar 和加速衰老 OXYS 大鼠心肌中 CryaB 的表达和磷酸化（Ser59：pS59）随年龄的变化。正如我们在这里所证明的那样，后者在高血压的背景下，在 12 个月的年龄就会发展为心肌病。使用了 20 天大、3 个月、12 个月和 24 个月的大鼠。CryaB mRNA 的表达（通过 RT-PCR 研究）和 CryaB 蛋白的表达（通过 Western blot 分析）在 Wistar 和 OXYS 大鼠的心肌中均随年龄增长而增加，但仅在 24 个月时，OXYS 大鼠的水平降低。CryaB 的磷酸化随年龄增长而增加。在所有大鼠中，磷酸化 CryaB 与去污剂可溶性部分的 pS59-CryaB 量之间均无关联。此外，心肌免疫染色显示，pS59-CryaB 在 OXYS 大鼠中的量大于对照动物。这种现象是由于 pS59-CryaB 从去污剂可溶性蛋白部分易位到去污剂不溶性部分所致。两种品系的心肌中，有丝分裂肌节（去污剂不溶性）中的 pS59-CryaB 量随年龄增长而增加，但在 OXYS 大鼠的心肌中增加更快，其积累先于心肌病的发展。磷酸化 CryaB 向肌节的易位影响收缩功能和肌原纤维组织至关重要的功能和结构特性（心肌细胞），并可能是心肌衰老的内源性机制的重要组成部分。
