Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China; Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan 430060, PR China.
Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China; Hubei Key Laboratory of Metabolic and Chronic Diseases, Wuhan 430060, PR China.
Metabolism. 2023 Sep;146:155658. doi: 10.1016/j.metabol.2023.155658. Epub 2023 Jul 9.
The prevalence of type 2 diabetes mellitus (T2DM) has increased over the past decades. Diabetic cardiomyopathy (DCM) is the leading cause of death in T2DM patients, however, the mechanism underlying DCM remains largely unknown. Here, we aimed to investigate the role of cardiac PR-domain containing 16 (PRDM16) in T2DM.
We modeled mice with cardiac-specific deletion of Prdm16 by crossing the floxed Prdm16 mouse model with the cardiomyocyte-specific Cre transgenic mouse. The mice were continuously fed a chow diet or high-fat diet combining with streptozotocin (STZ) for 24 weeks to establish a T2DM model. DB/DB and adequate control mice were given a single intravenous injection of adeno-associated virus 9 (AAV9) carrying cardiac troponin T (cTnT) promoter-driven small hairpin RNA targeting PRDM16 (AAV9-cTnT-shPRDM16) from the retro-orbital venous plexus to knockout Prdm16 in the myocardium. There were at least 12 mice in each group. Mitochondrial morphology and function were detected using transmission electron microscopy, western blot determining the protein level of mitochondrial respiratory chain complex, mitotracker staining and Seahorse XF Cell Mito Stress Test Kit. Untargeted metabolomics analysis and RNA-seq analysis were performed to determine the molecular and metabolic changes associated with Prdm16 deficiency. BODIPY and TUNEL staining were used to detect lipid uptake and apoptosis. Co-immunoprecipitation and ChIP assays were conducted to examine the potential underlying mechanism.
Prdm16 cardiac-specific deficiency accelerated cardiomyopathy and worsened cardiac dysfunction in mice with T2DM, aggravating mitochondrial dysfunction and apoptosis both in vivo and in vitro, while PRDM16 overexpression the deterioration. Prdm16 deficiency also caused cardiac lipid accumulation resulting in metabolic and molecular alterations in T2DM mouse models. Co-IP and luciferase assays confirmed that PRDM16 targeted and regulated the transcriptional activity, expression and interaction of PPAR-α and PGC-1α, while the overexpression of PPAR-α and PGC-1α reversed Prdm16 deficiency-induced cellular dysfunction in T2DM model. Moreover, PRDM16 regulated PPAR-α and PGC-1α and affected mitochondrial function by mainly depending on epigenetic regulation of H3K4me3.
These findings suggest that PRDM16 exerted its protective role in myocardial lipid metabolism and mitochondrial function in T2DM in a histone lysine methyltransferase activity-dependent manner by regulating PPAR-α and PGC-1α.
过去几十年，2 型糖尿病（T2DM）的患病率一直在上升。糖尿病心肌病（DCM）是 T2DM 患者死亡的主要原因，但 DCM 的发病机制仍知之甚少。在这里，我们旨在研究心脏 PR 结构域包含蛋白 16（PRDM16）在 T2DM 中的作用。
我们通过将 floxed Prdm16 小鼠模型与心肌细胞特异性 Cre 转基因小鼠杂交，构建了心脏特异性缺失 Prdm16 的小鼠模型。这些小鼠连续 24 周给予普通饮食或高脂肪饮食并结合链脲佐菌素（STZ），以建立 T2DM 模型。DB/DB 和足够的对照小鼠通过从眶后静脉丛给予携带肌钙蛋白 T（cTnT）启动子驱动的短发夹 RNA 的腺相关病毒 9（AAV9），从静脉内单次注射来敲除心肌中的 Prdm16，靶向 PRDM16（AAV9-cTnT-shPRDM16）。每组至少有 12 只小鼠。使用透射电子显微镜检测线粒体形态和功能，通过 Western blot 确定线粒体呼吸链复合物的蛋白水平，使用 mitotracker 染色和 Seahorse XF Cell Mito Stress Test Kit 检测线粒体功能。进行非靶向代谢组学分析和 RNA-seq 分析，以确定与 Prdm16 缺失相关的分子和代谢变化。使用 BODIPY 和 TUNEL 染色检测脂质摄取和细胞凋亡。进行共免疫沉淀和 ChIP 测定以检查潜在的潜在机制。
Prdm16 心脏特异性缺失加速了 T2DM 小鼠的心肌病和心功能障碍恶化，在体内和体外均加重了线粒体功能障碍和细胞凋亡，而 PRDM16 的过表达则加重了这种恶化。Prdm16 缺失还导致心脏脂质积累，导致 T2DM 小鼠模型的代谢和分子改变。免疫共沉淀和荧光素酶测定证实，PRDM16 靶向并调节了 PPAR-α 和 PGC-1α 的转录活性、表达和相互作用，而 PPAR-α 和 PGC-1α 的过表达逆转了 T2DM 模型中 Prdm16 缺失诱导的细胞功能障碍。此外，PRDM16 通过主要依赖组蛋白赖氨酸甲基化的表观遗传调控来调节 PPAR-α 和 PGC-1α 并影响线粒体功能。
这些发现表明，PRDM16 通过调节 PPAR-α 和 PGC-1α，以依赖组蛋白赖氨酸甲基转移酶活性的方式，在 T2DM 中发挥其在心肌脂质代谢和线粒体功能中的保护作用。
