Role of formaldehyde, formate and one-carbon metabolism in the female heart

项目总结 心血管疾病是美国男性和女性的主要死亡原因。近期 流行病学发现支持一种内在机制，即保护绝经前妇女免受许多 心血管病变，这种保护随着更年期而丧失。类似的保护作用也一直存在 在临床前模型中观察到的，表明了解女性心脏的正常生物学可能 为人类有效的心血管疗法提供洞察力。我们小组最近的研究表明， 在基线水平上，女性心脏的游离甲醛水平是男性的两倍。甲醛是一种高度 反应性电泳体是许多细胞代谢反应的副产物，已知可诱导 通过与DNA和蛋白质形成加合物而产生的细胞毒性。为了中和这种细胞毒性，甲醛 脱氢酶(FDH或GSNOR)和线粒体乙醛脱氢酶2(ALDH2)已经进化到 将甲醛氧化成甲酸盐，这可以作为一种碳源。一碳代谢对人体健康至关重要 生成氨基酸、嘌呤和胸腺嘧啶生物合成所需的构建块，但也生成 关键抗氧化剂和维持对一氧化氮合酶(NOS)至关重要的四氢生物蝶呤(BH4) 功能。有趣的是，女性心脏表现出比男性更强的外佣和ALDH2活性，以及更高的 内皮型一氧化氮合酶(ENOS)活性。我们的初步调查结果显示，外佣的活动和甲醛水平 随着卵巢切除(OVX)，女性心脏中内源性甲醛的含量下降，表明内源性甲醛是性激素- 依附的。因此，一碳循环中的甲醛-甲酸盐臂可能代表一种弹性 细胞毒性甲醛转化为甲酸盐维持有益和保护女性心脏的机制 BH4水平和NOS活性，但这一机制尚未在女性心脏中进行研究。此外，我们还 第一个发现外佣的丢失加剧了女性心脏的缺血性损伤，造成的原因是双重的 缺血后甲醛的增加，但ALDH2的激活挽救了女性的这一损伤表型 外佣-/-心脏。这些结果表明，FDH活性和/或甲醛的改变可以推动心肌梗死 女性的病理学，但需要更多的研究来定义甲醛甲酸盐的新作用- 女性心脏生物学中的碳臂。这项建议将解决这一重要的知识差距 具体目标如下：1)确定女性内源性甲醛产生的来源和定位 心脏和2)确定了甲醛-甲酸盐一碳臂和eNOS功能之间的潜在联系 女性的心。如果成功完成，这项研究将推进我们对 甲醛-甲酸单碳臂在女性心脏中的作用，并为这一途径如何 可作为治疗心血管疾病的靶点。

PROJECT SUMMARY Cardiovascular disease is the leading cause of death among men and women in the United States. Recent epidemiological findings support an intrinsic mechanism that protects pre-menopausal women from many cardiovascular pathologies and this protection is lost with menopause. Similar protective effects have been observed in preclinical models, suggesting that an understanding of the normal biology of the female heart could yield insight for effective cardiovascular therapeutics in humans. Recent work from our group demonstrates that free formaldehyde levels are two-fold higher at baseline in female hearts vs. males. Formaldehyde is a highly reactive electrophile produced as a byproduct of many cellular metabolic reactions and is known to induce cytotoxicity by forming adducts with DNA and protein. To counteract this cytotoxicity, formaldehyde dehydrogenase (FDH or GSNOR) and mitochondrial aldehyde dehydrogenase 2 (ALDH2) have evolved to oxidize formaldehyde to formate, which can act as a one-carbon source. One-carbon metabolism is essential for generating the building blocks required for amino acid, purine and thymine biosynthesis, but also for generating critical antioxidants and maintaining tetrahydrobiopterin (BH4), which is essential for nitric oxide synthase (NOS) function. Interestingly, female hearts exhibit increased FDH and ALDH2 activity vs. males, as well as higher endothelial NOS (eNOS) activity. Our preliminary findings show that FDH activity and formaldehyde levels decrease with ovariectomy (OVX) in female hearts, suggesting that endogenous formaldehyde is sex hormone- dependent. As such, the formaldehyde-formate arm of the one-carbon cycle may represent a resilient mechanism that benefits and protects female hearts by turning cytotoxic formaldehyde into formate to maintain BH4 levels and NOS activity, but this mechanism has not been examined in female hearts. Furthermore, we were the first to discover that the loss of FDH exacerbates ischemic injury in female hearts, resulting from a two-fold increase in post-ischemic formaldehyde, but ALDH2 activation rescued this injurious phenotype in female FDH-/- hearts. These results suggest that alterations to FDH activity and/or formaldehyde can drive myocardial pathology in females, but additional studies are needed to define a novel role for the formaldehyde-formate one- carbon arm in the biology of the female heart. This proposal will address this important knowledge gap in the following specific aims: 1) define the source and localization of endogenous formaldehyde generation in female hearts and 2) define a potential link between the formaldehyde-formate one-carbon arm and eNOS function in female hearts. If completed successfully, this study will advance our mechanistic understanding of the formaldehyde-formate one-carbon arm in the female heart and provide valuable insight into how this pathway may be targeted for the therapeutic treatment of cardiovascular disease.