Aberrant Glycosylation in the Left Ventricle and Plasma of Rats with Cardiac Hypertrophy and Heart Failure

Targeted proteomics focusing on post-translational modifications, including glycosylation, is a useful strategy for discovering novel biomarkers. To apply this strategy effectively to cardiac hypertrophy and resultant heart failure, we aimed to characterize glycosylation profiles in the left ventricle and plasma of rats with cardiac hypertrophy. Dahl salt-sensitive hypertensive rats, a model of hypertension-induced cardiac hypertrophy, were fed a high-salt (8% NaCl) diet starting at 6 weeks. As a result, they exhibited cardiac hypertrophy at 12 weeks and partially impaired cardiac function at 16 weeks compared with control rats fed a low-salt (0.3% NaCl) diet. Gene expression analysis revealed significant changes in the expression of genes encoding glycosyltransferases and glycosidases. Glycoproteome profiling using lectin microarrays indicated upregulation of mucin-type O-glycosylation, especially disialyl-T, and downregulation of core fucosylation on N-glycans, detected by specific interactions with Amaranthus caudatus and Aspergillus oryzae lectins, respectively. Upregulation of plasma α-l-fucosidase activity was identified as a biomarker candidate for cardiac hypertrophy, which is expected to support the existing marker, atrial natriuretic peptide and its related peptides. Proteomic analysis identified cysteine and glycine-rich protein 3, a master regulator of cardiac muscle function, as an O-glycosylated protein with altered glycosylation in the rats with cardiac hypertrophy, suggesting that alternations in O-glycosylation affect its oligomerization and function. In conclusion, our data provide evidence of significant changes in glycosylation pattern, specifically mucin-type O-glycosylation and core defucosylation, in the pathogenesis of cardiac hypertrophy and heart failure, suggesting that they are potential biomarkers for these diseases.

聚焦于包括糖基化（glycosylation）在内的翻译后修饰（post-translational modification）的靶向蛋白质组学（targeted proteomics），是发现新型生物标志物的有效研究策略。为将该策略有效应用于心肌肥厚及其引发的心力衰竭研究，本研究旨在解析心肌肥厚大鼠左心室与血浆中的糖基化谱特征。本研究采用的高血压诱导心肌肥厚动物模型为达尔盐敏感性高血压大鼠（Dahl salt-sensitive hypertensive rats），该模型大鼠于6周龄起喂食高盐（8% NaCl）饲料；结果显示，与喂食低盐（0.3% NaCl）饲料的对照组大鼠相比，模型组大鼠在12周龄时出现心肌肥厚，16周龄时心脏功能出现部分受损。基因表达分析结果显示，编码糖基转移酶（glycosyltransferases）与糖苷酶（glycosidases）的基因表达发生显著变化。通过凝集素微阵列（lectin microarrays）开展的糖蛋白组学（glycoproteome）分析表明，黏蛋白型O-糖基化（mucin-type O-glycosylation）尤其是双唾液酸-T（disialyl-T）的表达上调，而N-聚糖（N-glycans）上的核心岩藻糖基化（core fucosylation）则出现下调；上述两种变化分别通过与尾穗苋凝集素（Amaranthus caudatus lectin）和米曲霉凝集素（Aspergillus oryzae lectin）的特异性结合得以检测。血浆α-L-岩藻糖苷酶（α-L-fucosidase）活性上调被鉴定为心肌肥厚的潜在生物标志物，该标志物有望辅助现有标志物——心房利钠肽（atrial natriuretic peptide）及其相关肽类的临床应用。蛋白质组学分析鉴定出，富含半胱氨酸与甘氨酸的蛋白3（cysteine and glycine-rich protein 3）是心肌功能的核心调控因子，在心肌肥厚大鼠体内其为糖基化模式发生改变的O-糖基化蛋白，这提示O-糖基化的异常会影响其寡聚化过程与生物学功能。综上，本研究数据证实，在心肌肥厚与心力衰竭的发病进程中，糖基化模式发生了显著改变，尤其是黏蛋白型O-糖基化与核心去岩藻糖基化（core defucosylation），这提示上述糖基化变化可作为此类疾病的潜在生物标志物。