Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in the cardiac myosin binding protein-C (cMyBP-C) encoding gene MYBPC3. In the Netherlands, approximately 25% of patients carry the MYBPC3_c.2373InsG founder mutation. Most patients are heterozygous (MYBPC3^+/InsG) and have highly variable phenotypic expression, whereas homozygous (MYBPC3^InsG/InsG) patients have severe HCM at a young age. To improve understanding of disease progression and genotype-phenotype relationship based on the hallmarks of human HCM, we characterized mice with CRISPR/Cas9-induced heterozygous and homozygous mutations. At 18–28 weeks of age, we assessed the cardiac phenotype of Mybpc3^+/InsG and Mybpc3^InsG/InsG mice with echocardiography, and performed histological analyses. Cytoskeletal proteins and cardiomyocyte contractility of 3–4 week old and 18–28 week old Mybpc3_c.2373InsG mice were compared to wild-type (WT) mice. Expectedly, knock-in of Mybpc3_c.2373InsG resulted in the absence of cMyBP-C and our 18–28 week old homozygous Mybpc3_c.2373InsG model developed cardiac hypertrophy and severe left ventricular systolic and diastolic dysfunction, whereas HCM was not evident in Mybpc3^+/InsG mice. Mybpc3^InsG/InsG cardiomyocytes also presented with slowed contraction-relaxation kinetics, to a greater extent in 18–28 week old mice, partially due to increased levels of detyrosinated tubulin and desmin, and reduced cardiac troponin I (cTnI) phosphorylation. Impaired cardiomyocyte contraction-relaxation kinetics were successfully normalized in 18–28 week old Mybpc3^InsG/InsG cardiomyocytes by combining detyrosination inhibitor parthenolide and β-adrenergic receptor agonist isoproterenol. Both the 3–4 week old and 18–28 week old Mybpc3^InsG/InsG models recapitulate HCM, with a severe phenotype present in the 18–28 week old model.

肥厚型心肌病 (HCM) 通常是由心肌肌球蛋白结合蛋白 C (cMyBP-C) 编码基因MYBPC3 突变引起。在荷兰，大约 25% 的患者携带MYBPC3 _c.2373InsG创建者突变。大多数患者是杂合子 ( MYBPC3 ^+/InsG )，并且具有高度可变的表型表达，而纯合子 ( MYBPC3 ^InsG/InsG ) 患者在年轻时就患有严重的 HCM。为了加深对基于人类 HCM 标志的疾病进展和基因型-表型关系的理解，我们对具有 CRISPR/Cas9 诱导的杂合和纯合突变的小鼠进行了表征。在18-28周龄时，我们通过超声心动图评估了Mybpc3 ^+/InsG和Mybpc3 ^InsG/InsG小鼠的心脏表型，并进行了组织学分析。将3-4 周龄和 18-28 周龄Mybpc3 _c.2373InsG小鼠的细胞骨架蛋白和心肌细胞收缩力与野生型 (WT) 小鼠进行比较。不出所料， Mybpc3 _c.2373InsG的敲入导致 cMyBP-C 的缺失，并且我们的 18-28 周龄纯合Mybpc3 _c.2373InsG模型出现心脏肥大和严重的左心室收缩和舒张功能障碍，而 HCM 在Mybpc3中并不明显^+/InsG小鼠。Mybpc3 ^InsG/InsG心肌细胞还表现出收缩-舒张动力学减慢，这在 18-28 周龄小鼠中更为明显，部分原因是去酪氨酸微管蛋白和结蛋白水平增加，以及心肌肌钙蛋白 I (cTnI) 磷酸化减少。通过联合使用去酪氨酸抑制剂小白菊内酯和 β-肾上腺素能受体激动剂异丙肾上腺素， 18-28 周龄Mybpc3 ^InsG/InsG心肌细胞中受损的心肌细胞收缩-舒张动力学成功正常化。3-4 周龄和 18-28 周龄的Mybpc3 ^InsG/InsG模型均重现了 HCM，其中 18-28 周龄模型中存在严重的表型。