Apolipoprotein M: a novel regulator of myocardial Autophagy

项目总结/摘要 心力衰竭（HF）是全球死亡的主要原因， 这是一个迫切的临床需求。我实验室的长期愿景是，载脂蛋白可以用来 治疗HF。我们已经发现，载脂蛋白M（ApoM）的循环水平降低与 人HF的死亡率增加。ApoM的每一个标准差降低都与ApoM的加倍相关。 HF的死亡风险，一种独立于B型利钠肽、冠状动脉疾病 以及其他已知的风险因素。ApoM几乎完全由肝脏产生，由肝细胞分泌， 结合循环中HDL颗粒上的生物活性脂质鞘氨醇-1-磷酸（S1 P），最终 激活各种细胞类型上的G蛋白偶联S1 P受体;然而， ApoM可能增加HF生存率尚不清楚。 为了了解ApoM的心脏保护机制，我们利用阿霉素心脏毒性（DoxTox） 模型Dox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 发现Dox可以减少人类和小鼠的ApoM。在DoxTox模型中，增加ApoM可以改善 存活并防止Dox诱导的心功能障碍。在临床相关的急性髓性白血病模型中， 初步研究表明ApoM不干扰Dox抗癌功效。 我们的初步数据表明，ApoM减弱了Dox诱导的心肌自噬损伤。 我们发现ApoM增加了自噬通量，并保留了核转录因子EB（TFEB），这是一个主要的自噬因子。 与多种心肌病有关的自噬和溶酶体生物发生调节因子。我们的数据表明 ApoM驱动的自噬和核TFEB的保存是可推广到其他细胞的保护机制。 心肌病该R 01提案测试了ApoM通过典型的S1 P信号传导增强ApoM的假设。 心肌自噬并保留核TFEB以减弱DoxTox。目的1检测肝脏S1 P是否 Aim 2测试ApoM介导的心肌自噬是否需要S1 P受体， 自噬需要心肌细胞水平，Aim 3测试心肌细胞TFEB是否需要自噬。 ApoM的心脏保护作用。Aim 3还利用CUT&RUN测序的创新技术， 确定ApoM是否将TFEB导向特定的转录靶点，这将有助于阐明或证实 ApoM引导的TFEB下游的其他途径。这些目标的成功将通过以下方式确定机制： ApoM可以减弱DoxTox并改善HF的结局。

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.