Interplay between the effects of a Protein Kinase C phosphomimic (T204E) and a dilated cardiomyopathy mutation (K211Δ or R206W) in rat cardiac troponin T blunts the magnitude of muscle length-mediated crossbridge recruitment against the β-myosin heavy cha
Interplay between the effects of a Protein Kinase C phosphomimic (T204E) and a dilated cardiomyopathy mutation (K211Δ or R206W) in rat cardiac troponin T blunts the magnitude of muscle length-mediated crossbridge recruitment against the β-myosin heavy cha
复制标题
大鼠心肌肌钙蛋白 T 中蛋白激酶 C 拟磷 (T204E) 和扩张型心肌病突变 (K211α 或 R206W) 之间的相互作用减弱了肌肉长度介导的横桥募集对抗 β-肌球蛋白重链的程度
DOI：
10.1007/s10974-016-9448-2
复制
发表时间：
2016
影响因子：
2.7
通讯作者：
Chandra,Murali
中科院分区：
文献类型：
--
作者：
Michael,JohnJeshurun;Gollapudi,SampathK;Chandra,Murali
扩张型心肌病（DCM）患者的心力衰竭表现为收缩功能障碍和几种蛋白激酶C （PKC）亚型的上调。最近，我们证明了心肌肌钙蛋白T （TnT）的PKC磷酰体T204E的功能作用受到α-和β-肌球蛋白重链（MHC）亚型的不同调节。因此，我们假设T204E与TnT中dcm相关突变（K211Δ或R206W）之间的相互作用将以mhc依赖的方式调节与收缩功能相关的收缩参数。为了验证我们的假设，我们从正常大鼠（α-MHC）和丙硫脲嘧啶处理大鼠（β-MHC）中生成了5种TnT变异（野生型、K211Δ、K211Δ + T204E、R206W和R206W + T204E），并分别重组到脱膜心肌纤维中。对复合纤维进行了稳态和力学动态测试。α-MHC纤维的肌丝Ca2+敏感性（pCa50）受到K211Δ和R206W的降低，α-MHC纤维（~0.15 pCa单位）比β-MHC纤维（~0.06 pCa单位）降低的程度更大。然而，T204E仅在β-MHC纤维中加剧了两种突变体对pca50的衰减作用。此外，仅在β-MHC纤维中，肌肉长度（ML）介导的交叉桥（XB）募集的幅度降低了K211Δ + T204E (~ 47%), R206W（~ 34%）和R206W + T204E（~ 36%）。与主要表达β-MHC的人类心脏相关，我们的数据表明，DCM突变、PKC在TnT中的磷酰化和β-MHC之间的相互作用，通过减弱pca50和ml介导的XB募集的强度，导致收缩功能障碍。
Failing hearts of dilated cardiomyopathy (DCM)-patients reveal systolic dysfunction and upregulation of several Protein Kinase C (PKC) isoforms. Recently, we demonstrated that the functional effects of T204E, a PKC phosphomimic of cardiac troponin T (TnT), were differently modulated by α- and β-myosin heavy chain (MHC) isoforms. Therefore, we hypothesized that the interplay between the effects of T204E and a DCM-linked mutation (K211Δ or R206W) in TnT would modulate contractile parameters linked-to systolic function in an MHC-dependent manner. To test our hypothesis, five TnT variants (wildtype, K211Δ, K211Δ + T204E, R206W, and R206W + T204E) were generated and individually reconstituted into demembranated cardiac muscle fibers from normal (α-MHC) and propylthiouracil-treated (β-MHC) rats. Steady-state and mechano-dynamic measurements were performed on reconstituted fibers. Myofilament Ca2+sensitivity (pCa50) was decreased by both K211Δ and R206W to a greater extent in α-MHC fibers (~0.15 pCa units) than in β-MHC fibers (~0.06 pCa units). However, T204E exacerbated the attenuating influence of both mutants on pCa50only in β-MHC fibers. Moreover, the magnitude of muscle length (ML)-mediated crossbridge (XB) recruitment was decreased by K211Δ + T204E (~47 %), R206W (~34 %), and R206W + T204E (~36 %) only in β-MHC fibers. In relevance to human hearts, which predominantly express β-MHC, our data suggest that the interplay between the effects of DCM mutations, PKC phosphomimic in TnT, and β-MHC lead to systolic dysfunction by attenuating pCa50and the magnitude of ML-mediated XB recruitment.