Apolipoprotein M: a novel regulator of myocardial Autophagy

项目摘要/摘要 心力衰竭是世界范围内死亡的一个主要原因，正在寻找治疗心力衰竭的新方法。 代表着一种紧急的临床需求。我的实验室的长期愿景是载脂蛋白可以用来 治疗心衰。我们发现，循环中载脂蛋白M(ApoM)水平的降低与 人类心力衰竭死亡率增加。APOM中的每一个标准差减少都与两倍的 心力衰竭的死亡风险，这是一种独立于B型利钠肽、冠心病、 以及其他已知的风险因素。载脂蛋白几乎完全由肝脏制造，由肝细胞分泌，并且 最终将生物活性脂鞘氨醇-1-磷酸(S1P)结合到循环中的高密度脂蛋白颗粒上 激活G蛋白偶联的S1P受体在不同类型的细胞上；然而， APOM可能会增加心衰的存活率，目前尚不清楚。 为了了解apom的心脏保护机制，我们使用了阿霉素心脏毒性(Doxtox)。 模特。DOX被用于治疗多种人类癌症，但其使用受到DoxTox和长期HF的限制。我们 已经发现Dox可以减少人类和小鼠的载脂蛋白。在DoxTox模型中，增加apom可以提高 存活并预防Dox引起的心功能障碍。在一个临床相关的急性髓系白血病模型中， 初步研究表明，载脂蛋白不干扰多柔比星的抗癌效果。 我们的初步数据表明，载脂蛋白可减轻Dox诱导的心肌自噬损伤。 我们发现载脂蛋白增加了自噬通量，并保留了核转录因子EB(TFEB)，这是一种主要的 自噬和溶酶体生物发生的调节因子与多发性心肌病有关。我们的数据显示 APOM驱动的自噬和核TFEB的保存是可推广到其他 心肌病。R01提案测试了apom通过规范的S1P信令增强 心肌自噬并保留核TFEB以减弱DoxTox。AIM 1检测肝脏S1P Apom介导的心肌自噬需要产生；Aim 2测试S1P受体是否在 自噬需要心肌细胞水平，目标3测试心肌细胞TFEB是否需要 载脂蛋白的心脏保护作用。Aim 3还利用创新的切割和运行测序技术来 确定载脂蛋白是否将TFEB定向到特定的转录靶点，这将有助于阐明或确认 TFEB下游的其他通道，由APOM指示。这些目标的成功将通过以下方式确定机制 哪种载脂蛋白可以减弱DoxTox并改善心衰的预后。

PROJECT SUMMARY/ABSTRACT Heart failure (HF) is a major cause of mortality worldwide, and identifying novel therapies to treat HF represents an urgent clinical need. The long-term vision of my laboratory is that apolipoproteins can be used to treat HF. We have discovered that reduced circulating levels of apolipoprotein M (ApoM) are associated with increased mortality in human HF. Each standard deviation reduction in ApoM is associated with a doubling of mortality risk in HF, an association that is independent of B-type natriuretic peptide, coronary artery disease, and other known risk factors. ApoM is made almost exclusively by the liver, secreted by hepatocytes, and binds the bioactive lipid sphingosine-1-phosphate (S1P) on HDL particles in the circulation, ultimately activating G-protein coupled S1P receptors on various cell types; however, the precise mechanism by which ApoM may increase HF survival is unknown. To understand mechanisms of cardioprotection by ApoM, we utilized a doxorubicin cardiotoxicity (DoxTox) model. Dox is utilized to treat multiple human cancers, but its use is limited by DoxTox and long-term HF. We have discovered that Dox reduces ApoM in humans and mice. In DoxTox models, increasing ApoM improves survival and prevents Dox-induced cardiac dysfunction. In a clinically relevant acute myeloid leukemia model, preliminary studies indicate ApoM does not interfere with Dox anti-cancer efficacy. Our preliminary data suggest that ApoM attenuates Dox-induced autophagic impairment in the myocardium. We find ApoM increases autophagic flux and preserves nuclear transcription factor EB (TFEB), a master regulator of autophagy and lysosomal biogenesis implicated in multiple cardiomyopathies. Our data suggest ApoM-driven autophagy and preservation of nuclear TFEB are protective mechanisms generalizable to other cardiomyopathies. This R01 proposal tests the hypothesis that ApoM, via canonical S1P signaling, enhances myocardial autophagy and preserves nuclear TFEB to attenuate DoxTox. Aim 1 tests whether hepatic S1P production is required for ApoM-mediated myocardial autophagy; Aim 2 tests whether the S1P receptor at the level of cardiomyocyte is required for autophagy, and Aim 3 tests whether cardiomyocyte TFEB is required for the cardioprotective effects of ApoM. Aim 3 also utilizes the innovative technique of CUT&RUN sequencing to determine whether ApoM directs TFEB to specific transcriptional targets, which will help elucidate or confirm other pathways downstream of TFEB directed by ApoM. Success of these aims will identify mechanisms by which ApoM can attenuate DoxTox and improve outcomes in HF.