PDF(Pubmed)
Abstract：
Aging is associated with skeletal muscle strength decline and cardiac diastolic dysfunction. The structural arrangements of the sarcomeric proteins, such as myosin binding protein-C (MyBP-C) are shown to be pivotal in the pathogenesis of diastolic dysfunction. Yet, the role of fast (fMyBP-C) and slow (sMyBP-C) skeletal muscle MyBP-C remains to be elucidated. Herein, we aimed to characterize MyBP-C and its paralogs in the fast tibialis anterior (TA) muscle from adult and old mice. Immunoreactivity preparations showed that the relative abundance of the fMyBP-C paralog was greater in the TA of both adult and old, but no differences were noted between groups. We further found that the expression level of cardiac myosin binding protein-C (cMyBP-C), an important modulator of cardiac output, was lowered by age. Standard SDS-PAGE along with Pro-Q Diamond phosphoprotein staining did not identify age-related changes in phosphorylated MyBP-C proteins from TA and cardiac muscles; however, it revealed that MyBP-C paralogs in fast skeletal and cardiac muscle were highly phosphorylated. Mass spectrometry further identified glycogen phosphorylase, desmin, actin, troponin T, and myosin regulatory light chain 2 as phosphorylated myofilament proteins in both ages. MyBP-C protein-bound carbonyls were determined using anti-DNP immunostaining and found the carbonyl level of fMyBP-C, sMyBP-C, and cMyBP-C to be similar between old and adult animals. In summary, our data showed some differences regarding the MyBP-C paralog expression and identified an age-related reduction of cMyBP-C expression. Future studies are needed to elucidate which are the age-driven post-translational modifications in the MyBP-C paralogs.
摘要：
衰老与骨骼肌力量下降和心脏舒张功能障碍有关。肌节蛋白的结构排列，例如肌球蛋白结合蛋白-C(MyBP-C)被证明在舒张功能障碍的发病机制中起关键作用。然而，快速（fMyBP-C）和慢速（sMyBP-C）骨骼肌MyBP-C的作用仍有待阐明。在这里，我们旨在表征成年和老年小鼠的快速胫骨前（TA）肌肉中的MyBP-C及其旁系同源物。免疫反应性制剂表明，fMyBP-C旁系同源物的相对丰度在成年人和老年人的TA中均较高，但组间无差异.我们进一步发现心肌肌球蛋白结合蛋白-C(cMyBP-C)的表达水平,一个重要的心输出量调制器，被年龄降低了。标准SDS-PAGE和Pro-QDiamond磷蛋白染色无法识别TA和心肌磷酸化MyBP-C蛋白的年龄相关变化；然而，它显示，快速骨骼肌和心肌中的MyBP-C旁系同源物高度磷酸化。质谱进一步鉴定糖原磷酸化酶，desmin,肌动蛋白，肌钙蛋白T,和肌球蛋白调节轻链2在两个年龄段都是磷酸化的肌丝蛋白。使用抗DNP免疫染色确定MyBP-C蛋白结合的羰基，并发现fMyBP-C的羰基水平，sMyBP-C,和cMyBP-C在老年和成年动物之间相似。总之,我们的数据显示在MyBP-C旁系同源表达方面存在一些差异,并发现cMyBP-C表达与年龄相关的降低.需要进一步的研究来阐明MyBP-C旁系同源物中哪些是年龄驱动的翻译后修饰。
