Stimulatory Effects of Balanced Deep Sea Water on Mitochondrial Biogenesis and Function

The worldwide prevalence of metabolic diseases, including obesity and diabetes, is increasing. Mitochondrial dysfunction is recognized as a core feature of these diseases. Emerging evidence also suggests that defects in mitochondrial biogenesis, number, morphology, fusion, and fission, contribute to the development and progression of metabolic diseases. Our previous studies revealed that balanced deep-sea water (BDSW) has potential as a treatment for diabetes and obesity. In this study, we aimed to investigate the mechanism by which BDSW regulates diabetes and obesity by studying its effects on mitochondrial metabolism. To determine whether BDSW regulates mitochondrial biogenesis and function, we investigated its effects on mitochondrial DNA (mtDNA) content, mitochondrial enzyme activity, and the expression of transcription factors and mitochondria specific genes, as well as on the phosphorylation of signaling molecules associated with mitochondria biogenesis and its function in C2C12 myotubes. BDSW increased mitochondrial biogenesis in a time and dose-dependent manner. Quantitative real-time PCR revealed that BDSW enhances gene expression of PGC-1α, NRF1, and TFAM for mitochondrial transcription; MFN1/2 and DRP1 for mitochondrial fusion; OPA1 for mitochondrial fission; TOMM40 and TIMM44 for mitochondrial protein import; CPT-1α and MCAD for fatty acid oxidation; CYTC for oxidative phosphorylation. Upregulation of these genes was validated by increased mitochondria staining, CS activity, CytC oxidase activity, NAD+ to NADH ratio, and the phosphorylation of signaling molecules such as AMPK and SIRT1. Moreover, drinking BDSW remarkably improved mtDNA content in the muscles of HFD-induced obese mice. Taken together, these results suggest that the stimulatory effect of BDSW on mitochondrial biogenesis and function may provide further insights into the regulatory mechanism of BDSW-induced anti-diabetic and anti-obesity action.

包括肥胖与糖尿病在内的代谢性疾病，全球患病率正持续攀升。线粒体功能障碍已被公认为这类疾病的核心病理特征。越来越多的新兴研究证据表明，线粒体生物发生、数量、形态、融合与分裂过程出现异常，会推动代谢性疾病的发生与进展。本团队既往研究显示，平衡深海水（balanced deep-sea water, BDSW）具备用于治疗糖尿病与肥胖的潜力。本研究旨在通过探究BDSW对线粒体代谢的调控作用，阐明其改善糖尿病与肥胖的分子机制。为验证BDSW是否可调控线粒体生物发生与功能，本研究以C2C12肌管为模型，检测了BDSW对线粒体DNA（mitochondrial DNA, mtDNA）含量、线粒体酶活性、转录因子及线粒体特异性基因的表达水平，以及与线粒体生物发生和功能相关的信号分子磷酸化水平的影响。实验结果显示，BDSW可通过时间与剂量依赖的方式促进线粒体生物发生。实时荧光定量PCR结果表明，BDSW可上调如下基因的表达：参与线粒体转录的PGC-1α、NRF1及TFAM；调控线粒体融合的MFN1/2与DRP1；介导线粒体分裂的OPA1；参与线粒体蛋白转运的TOMM40与TIMM44；调控脂肪酸氧化的CPT-1α与MCAD；以及参与氧化磷酸化的CYTC。上述基因的上调表达，可通过线粒体染色增强、柠檬酸合酶（citrate synthase, CS）活性提升、细胞色素C氧化酶（cytochrome C oxidase, CytC oxidase）活性升高、烟酰胺腺嘌呤二核苷酸（nicotinamide adenine dinucleotide, NAD+）与还原型烟酰胺腺嘌呤二核苷酸（reduced nicotinamide adenine dinucleotide, NADH）比值改善，以及腺苷酸活化蛋白激酶（AMP-activated protein kinase, AMPK）、沉默信息调节因子1（Sirtuin 1, SIRT1）等信号分子磷酸化水平上调得到验证。此外，给高脂饮食（high fat diet, HFD）诱导的肥胖小鼠饮用BDSW，可显著提升其肌肉组织中的mtDNA含量。综上，本研究结果表明，BDSW对线粒体生物发生与功能的促进作用，可为阐明其抗糖尿病与抗肥胖的调控机制提供新的理论依据。