Elucidation of the molecular mechanisms of myocardial autophagy regulation and MAPK pathway inactivation by SPRED proteins

阐明SPRED蛋白调节心肌自噬和MAPK通路失活的分子机制

• 批准号: 447358241
• 负责人: Professor Dr. Kai Schuh
• 金额: --
• 依托单位: Lehrstuhl für Physiologie I - Schwerpunkt vegetative Physiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/447358241?language=en
• 关键词: Elucidation; molecular; mechanisms; myocardial; autophagy

Cardiac functionality is dependent on a balanced protein turnover. Accordingly, regulated protein decay is critical to maintain cardiac function. In this project, we will investigate if deficiency of SPRED2, an intracellular repressor of ERK-MAPK signaling markedly expressed in human heart, results in impaired autophagy, heart failure, and shortened lifespan. SPRED2-deficient mice show cardiomyocyte hypertrophy, cardiac fibrosis, impaired electrical excitability, and severe arrhythmias. Mechanistically, cardiomyocyte dysfunction results from ERK hyperactivation and dysregulated autophagy, observed as accumulation of vesicles, vacuolar structures, and degenerated mitochondria. The diminished autophagic flux in SPRED2-/- hearts was reflected by a reduced LC3-II/LC3-I ratio and by decreased Atg7, Atg4B and Atg16L expression. Furthermore, the autophagosomal adaptors p62 and NBR1 and lysosomal CathepsinD accumulated in SPRED2-/- hearts. However, the molecular mechanisms how SPRED2 regulates autophagy remain enigmatic. SPRED2 has no intrinsic enzymatic activity, which makes an alternative mechanism of regulation of autophagy necessary. In this grant proposal, we would like to investigate in detail the pathways necessary to clarify how SPRED2 regulates vesicle transport required for RTK signaling but also final RTK inactivation by autophagy in cardiac myocytes. Elucidation of these molecular processes in vivo and ex vivo will be relevant in many areas of medical research, as a variety of diseases are triggered by disorders of MAPK pathway inactivation (“Rasopahties”), of intracellular transport, and lack of fusion of lysosomes (“Lysosomal Storage Diseases”).

心脏功能依赖于平衡的蛋白质周转。因此，受调节的蛋白质衰变对于维持心脏功能至关重要。在这个项目中，我们将研究是否SPRED 2，一个细胞内抑制ERK-MAPK信号显着表达在人类心脏，导致受损的自噬，心力衰竭，寿命缩短。SPRED 2缺陷小鼠表现出心肌细胞肥大、心脏纤维化、电兴奋性受损和严重心律失常。从机制上讲，心肌细胞功能障碍是由ERK过度激活和失调的自噬引起的，观察到囊泡、空泡结构和变性线粒体的积累。SPRED 2-/-心脏中减少的自噬通量通过降低的LC 3-II/LC 3-I比率和降低的Atg 7、Atg 4 B和Atg 16 L表达来反映。此外，自噬体衔接子p62和NBR 1以及溶酶体组织蛋白酶D在SPRED 2-/-心脏中积累。然而，SPRED 2如何调节自噬的分子机制仍然是个谜。SPRED 2没有内在的酶活性，这使得调节自噬的替代机制成为必要。在这项资助提案中，我们希望详细研究必要的途径，以澄清SPRED 2如何调节RTK信号传导所需的囊泡运输，以及心肌细胞中自噬导致的最终RTK失活。体内和离体这些分子过程的阐明将在医学研究的许多领域中是相关的，因为多种疾病是由MAPK途径失活（“Rasopahties”）、细胞内转运和缺乏溶酶体融合（“溶酶体贮积病”）的病症触发的。