Molecular Mechanisms and Treatment of Primary Amyloid AL Cardiomyopathy

描述（由申请人提供）：淀粉样变性是一类人类疾病，其中蛋白质前体表现出二级结构改变，并在组织中形成不溶性蛋白质聚集体。原发性淀粉样变性（AL）是最常见的系统性淀粉样变性，由浆细胞克隆性产生免疫球蛋白轻链（LC）蛋白引发。虽然AL聚集体可在许多器官中形成，但心脏沉积与最差预后有关。由此产生的淀粉样AL型心肌病的独特之处在于，它对标准的心力衰竭治疗方案没有反应，并且伴有超过50%的5年死亡率，与最具侵袭性的癌症类型相当。迄今为止，由于缺乏对这种疾病过程背后的分子机制的理解，除了原位移植之外，还没有治疗AL心肌病的方法。在过去的资助周期中，我们的实验室首次提供了AL心肌病发病机制的见解，并证明了人类淀粉样蛋白LC （AL-LC）通过激活非规范p38 MAPK信号级联引起心脏毒性作用，随后导致细胞氧化应激增加，钙稳态改变，细胞收缩性受损，最终导致细胞死亡。通过使用无偏倚基因组学，我们最近从AL-LC治疗的心肌细胞和外植AL心肌病的人类心脏的全基因组转录组分析中发现了一种新的LC毒性心肌细胞调节剂，STC1。此外，我们发现STC1的上调依赖于上游p38 MAPK的激活，并且STC1定位于心肌细胞线粒体，在那里它通过抑制自噬清除诱导离体成年心肌细胞的ROS生成、细胞功能障碍和死亡。根据我们之前的研究结果和初步数据，在这个竞争性更新应用中，我们建议验证我们的中心假设，即循环AL-LC通过STC1线粒体功能损伤和细胞自噬失调对心肌细胞产生有害影响。利用分子和细胞生物学、生物化学和生理学的多学科方法，结合分离的心肌细胞和体内小鼠模型，我们将确定STC1 （Aim 1）和自噬（Aim 2）在AL-LC诱导的有害事件中的必要性和充分性。这项工作代表了我们对淀粉样蛋白心肌病机制的持续深入研究。

DESCRIPTION (provided by applicant): Amyloidosis represents a group of human diseases in which protein precursors exhibit altered secondary structure and form insoluble protein aggregates in tissues. Primary amyloidosis (AL) is the most common systemic amyloidosis and is initiated by the clonal production of immunoglobulin light chain (LC) proteins by plasma cells. While AL aggregates may form in numerous organs, cardiac deposition is associated with the worst prognosis. The resulting amyloid AL cardiomyopathy is unique in that it is not responsive to standard heart failure regimens and is accompanied by greater than 50% mortality over 5 years, comparable to the most aggressive types of cancers. To date, there is no treatment for AL cardiomyopathy, other than orthotopic transplantation, owing to the lack of understanding of the molecular mechanisms that underlie this disease process. During the past funding cycle, our laboratory has provided the first mechanistic insight into the pathogenesis of AL cardiomyopathy and demonstrated that human amyloidogenic LC (AL-LC) provoke a cardiotoxic effects via activation of non-canonical p38 MAPK signaling cascade and subsequently lead to increase cellular oxidant stress, altered calcium homeostasis, impaired cellular contractility, and, eventually, cell death. Through the use of unbiased genomics we have recently identified a novel cardiomyocyte regulator of LC toxicity, stanniocalcin-1 (STC1), from whole genome transcriptomic analyses of AL-LC treated cardiomyocytes and explanted human hearts with AL cardiomyopathy. Moreover, we find that upregulation of STC1 is dependent upon upstream p38 MAPK activation, and that STC1 localizes to the cardiomyocyte mitochondria, where it induces ROS generation, cellular dysfunction and death in isolated adult cardiomyocytes via the inhibition of autophagy clearance. With our prior findings and preliminary data, in this competitive renewal application, we propose to test our central hypothesis that that circulating AL-LC imparts a deleterious effect on cardiomyocytes via STC1 impairment of mitochondrial function and dysregulation of cellular autophagy. Utilizing a multidisciplinary approach of molecular and cellular biology, biochemistry, and physiology, coupled with isolated cardiomyocyte and in vivo mouse models, we will determine the necessity and sufficiency of STC1 (Aim 1) and the role of autophagy (Aim 2) in AL-LC induced deleterious events. This work represents our continued intensive investigation of the mechanism underlying amyloid cardiomyopathy.