Mutation location of HCM-causing troponin T mutations defines the degree of myofilament dysfunction in human cardiomyocytes.
Mutation location of HCM-causing troponin T mutations defines the degree of myofilament dysfunction in human cardiomyocytes.
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DOI：
10.1016/j.yjmcc.2020.10.006
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发表时间：
2021-01
影响因子：
5
通讯作者：
van der Velden J
中科院分区：
文献类型：
--
作者：
Schuldt M;Johnston JR;He H;Huurman R;Pei J;Harakalova M;Poggesi C;Michels M;Kuster DWD;Pinto JR;van der Velden J
肥厚型心肌病患者的临床结局不仅取决于致病突变，还受多种疾病修饰物的影响。在这里，我们定义了肌钙蛋白T突变I79 N、R94 C和R278 C的突变位置和突变蛋白剂量的作用。我们在透化的单个人心肌细胞以及携带R278 C突变的心脏病患者样本中测定了肌钙蛋白交换后的肌丝功能。值得注意的是，我们发现小剂量的突变蛋白足以对I79 N和R94 C突变的肌丝Ca 2+敏感性产生最大作用，而突变位置决定了这种作用的大小。I79 N和R94 C掺入增加了肌丝Ca ~（2+）敏感性，R278 C掺入在低、中剂量时增加了Ca ~（2+）敏感性，而在高剂量时降低了Ca ~（2+）敏感性。所有三种cTnT突变体均显示出降低的细丝结合亲和力，这与心肌细胞中突变肌钙蛋白复合物相对较低的最大交换（50.5 ± 5.2%）相一致。相应地，在显示50.0 ± 3.7%突变mRNA的两个患者样品中发现32.2 ± 4.0%突变R278 C。根据显示具有完全相同突变的患者的临床变异性的研究，我们观察到具有R278 C突变的患者的功能性单细胞水平的变异性。肌丝特性的这些差异不能用突变蛋白量的差异来解释。在单个人心肌细胞中使用肌钙蛋白交换，我们表明TNNT 2突变诱导的肌丝Ca 2+敏感性变化取决于突变位置，而所有突变体均显示出降低的细丝结合亲和力。R278 C观察到的特异性突变效应不能转化为患者心肌细胞的肌丝功能，并且最有可能通过其他（翻译后）肌钙蛋白修饰来解释。总的来说，我们的研究表明，突变位置的肌丝Ca 2+敏感性的变化，而只有R278 C突变显示出高度剂量依赖性的影响肌丝功能。
The clinical outcome of hypertrophic cardiomyopathy patients is not only determined by the disease-causing mutation but influenced by a variety of disease modifiers. Here, we defined the role of the mutation location and the mutant protein dose of the troponin T mutations I79N, R94C and R278C. We determined myofilament function after troponin exchange in permeabilized single human cardiomyocytes as well as in cardiac patient samples harboring the R278C mutation. Notably, we found that a small dose of mutant protein is sufficient for the maximal effect on myofilament Ca2+-sensitivity for the I79N and R94C mutation while the mutation location determines the magnitude of this effect. While incorporation of I79N and R94C increased myofilament Ca2+-sensitivity, incorporation of R278C increased Ca2+-sensitivity at low and intermediate dose, while it decreased Ca2+-sensitivity at high dose. All three cTnT mutants showed reduced thin filament binding affinity, which coincided with a relatively low maximal exchange (50.5 ± 5.2%) of mutant troponin complex in cardiomyocytes. In accordance, 32.2 ± 4.0% mutant R278C was found in two patient samples which showed 50.0 ± 3.7% mutant mRNA. In accordance with studies that showed clinical variability in patients with the exact same mutation, we observed variability on the functional single cell level in patients with the R278C mutation. These differences in myofilament properties could not be explained by differences in the amount of mutant protein. Using troponin exchange in single human cardiomyocytes, we show that TNNT2 mutation-induced changes in myofilament Ca2+-sensitivity depend on mutation location, while all mutants show reduced thin filament binding affinity. The specific mutation-effect observed for R278C could not be translated to myofilament function of cardiomyocytes from patients, and is most likely explained by other (post)-translational troponin modifications. Overall, our studies illustrate that mutation location underlies variability in myofilament Ca2+-sensitivity, while only the R278C mutation shows a highly dose-dependent effect on myofilament function.
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影响因子：
10.8
作者：
Ho CY;Charron P;Richard P;Girolami F;Van Spaendonck-Zwarts KY;Pinto Y
通讯作者：
Pinto Y
影响因子：
1.9
作者：
Capek, Pavel;Vondrasek, Jiri;Brdicka, Radim
通讯作者：
Brdicka, Radim
DOI：
10.1007/s12265-015-9624-6
发表时间：
2015-06-01
影响因子：
3.4
作者：
Gajendrarao, Poornima;Krishnamoorthy, Navaneethakrishnan;Yacoub, Magdi
通讯作者：
Yacoub, Magdi
影响因子：
8
作者：
Helms, Adam S.;Tang, Vi T.;Day, Sharlene M.
通讯作者：
Day, Sharlene M.
影响因子：
--
作者：
Martins, Adriano S.;Parvatiyar, Michelle S.;Pinto, Jose R.
通讯作者：
Pinto, Jose R.