Acute exercise modifies titin phosphorylation and increases cardiac myofilament stiffness
Acute exercise modifies titin phosphorylation and increases cardiac myofilament stiffness
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DOI：
10.3389/fphys.2014.00449
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发表时间：
2014-11-20
影响因子：
4
通讯作者：
Krueger, Martina
中科院分区：
文献类型：
--
作者：
Mueller, Anna E.;Kreiner, Matthias;Krueger, Martina
基于肌联蛋白的肌丝刚度很大程度上是通过其弹性 l 带区域 N2-Bus（降低被动刚度，PT）和 PEVK（增加 PT）的磷酸化来调节的。在这里，我们测试了以下假设：剧烈运动会改变肌动蛋白磷酸化并改变肌丝硬度。成年大鼠在跑步机上运动 15 分钟，未经训练的动物作为对照。使用针对 N2-Bus 区域中的 Ser4099 和 Ser4010（分别依赖于 PKG 和 PKA）以及针对 PEVK 区域中的 Ser11878 和 Ser 12022（分别依赖于 PKC α 和 CaMKII δ）的磷酸特异性抗体，通过蛋白质印迹分析测定肌联蛋白磷酸化。通过将分离的带皮心肌细胞逐步拉伸至1.9至2.4μm范围内的肌节长度（SL）来确定被动张力，并显示与对照相比，运动样品的PT显着增加。在心脏样本中，Ser4099 处的 titin N2-Bus 磷酸化显着降低 40%，但 Ser4010 处未观察到显着变化。 Ser11878 位点的 PEVK 磷酸化显着增加，这可能是由观察到的运动诱导的 PKCot 活性增加介导的。有趣的是，在训练样本中 Ser12022 的相对磷酸化显着降低。令人惊讶的是，在剧烈运动动物的骨骼样本中，我们检测到 Ser11878 处的 PEVK 磷酸化显着降低，而 Ser12022 磷酸化显着增加；然而，PKCot 活性保持不变。总之，我们的数据表明，单次 15 分钟的运动会影响肌联蛋白结构域磷酸化和基于肌联蛋白的肌细胞硬度，对心肌和骨骼肌组织的影响明显不同。观察到的肌动蛋白硬度变化可能在调整心肌和骨骼肌的被动和主动特性以适应增加的体力活动方面发挥重要作用。
Titin-based myofilament stiffness is largely modulated by phosphorylation of its elastic l-band regions N2-Bus (decreases passive stiffness, PT) and PEVK (increases PT). Here, we tested the hypothesis that acute exercise changes titin phosphorylation and modifies myofilament stiffness. Adult rats were exercised on a treadmill for 15 min, untrained animals served as controls. Titin phosphorylation was determined by Western blot analysis using phosphospecific antibodies to Ser4099 and Ser4010 in the N2-Bus region (PKG and PKA-dependent. respectively), and to Ser11878 and Ser 12022 in the PEVK region (PKC alpha and CaMKII delta-dependent, respectively). Passive tension was determined by step-wise stretching of isolated skinned cardiomyocytes to sarcomere length (SL) ranging from 1.9 to 2.4 mu m and showed a significantly increased PT from exercised samples, compared to controls. In cardiac samples titin N2-Bus phosphorylation was significantly decreased by 40% at Ser4099, however, no significant changes were observed at Ser4010. PEVK phosphorylation at Ser11878 was significantly increased, which is probably mediated by the observed exercise-induced increase in PKCot activity. Interestingly, relative phosphorylation of Ser12022 was substantially decreased in the exercised samples. Surprisingly, in skeletal samples from acutely exercised animals we detected a significant decrease in PEVK phosphorylation at Ser11878 and an increase in Ser12022 phosphorylation; however, PKCot activity remained unchanged. In summary, our data show that a single exercise bout of 15 min affects titin domain phosphorylation and titin-based myocyte stiffness with obviously divergent effects in cardiac and skeletal muscle tissues. The observed changes in titin stiffness could play an important role in adapting the passive and active properties of the myocardium and the skeletal muscle to increased physical activity.