Molecular Mechanisms and Treatment of Primary Amyloid AL Cardiomyopathy

描述（由申请人提供）：淀粉样变性是一组人类疾病，其中蛋白质前体表现出改变的二级结构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相关。由此产生的淀粉样AL心肌病是独特的，因为它对标准心力衰竭方案没有反应，并且伴随着超过50%的死亡率超过5年，与最具侵袭性的癌症类型相当。到目前为止，除了原位移植外，还没有治疗AL心肌病的方法，这是由于对这种疾病过程的分子机制缺乏了解。在过去的资助周期中，我们的实验室首次对AL心肌病的发病机制进行了深入研究，并证明了人淀粉样蛋白生成性LC（AL-LC）通过激活非经典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，细胞收缩力受损，最终导致细胞死亡。通过使用无偏见的基因组学，我们最近确定了一种新的心肌细胞调节LC毒性，斯钙素-1（STC 1），从全基因组转录组分析AL-LC治疗的心肌细胞和AL心肌病患者的心脏。此外，我们发现STC 1的上调依赖于上游p38 MAPK激活，并且STC 1定位于心肌细胞线粒体，在那里它通过抑制自噬清除诱导分离的成年心肌细胞中的ROS产生、细胞功能障碍和死亡。根据我们先前的发现和初步数据，在这种竞争性更新应用中，我们建议测试我们的中心假设，即循环AL-LC通过STC 1损伤线粒体功能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STC 1（Aim 1）的必要性和充分性以及自噬（Aim 2）在AL-LC诱导的有害事件中的作用。这项工作代表了我们对淀粉样心肌病潜在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.