Regulation of the cochaperone BAG3 and chaperone-assisted selective autophagy by Hippo kinases

Hippo 激酶对辅助伴侣 BAG3 和伴侣辅助选择性自噬的调节

• 批准号: 279436271
• 负责人: Professor Dr. Jörg Höhfeld
• 金额: --
• 依托单位: Institut für Zellbiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/279436271?language=en
• 关键词: Regulation; cochaperone; BAG3; chaperone; assisted

The cochaperone BAG3 (BCL2-associated athanogene-3) is a key proteostasis factor in muscle, immune and neuronal cells. In addition, its overexpression contributes to oncogenic transformation. BAG3 induces a chaperone-assisted and ubiquitin-dependent autophagy pathway, called CASA (chaperone-assisted selective autophagy). The pathway mediates the lysosomal degradation of nonnative chaperone clients, such as the actin-anchoring protein filamin following its mechanical unfolding in contracting muscles and adherent cells. Besides its degradation-inducing activity, BAG3 also regulates protein synthesis. The cochaperone interacts with components of the Hippo signaling pathway to facilitate filamin expression. The BAG3-mediated coregulation of protein degradation and protein synthesis is essential for maintaining the actin cytoskeleton under mechanical strain. Here we propose to analyze the impact of Hippo signaling on BAG3 function and CASA activity. The project is based on our identification of multiple Hippo kinases in association with BAG3. Our preliminary data show that at least one of these kinases directly controls CASA activity in smooth muscle cells. We will apply biochemical and cell biological assays to verify functional interactions between Hippo kinases and the CASA machinery in muscle and neuronal cells. Phosphoproteomics will be performed to identify Hippo phosphorylation sites in CASA components, and their importance for BAG3 and CASA regulation will be explored. Finally, differentiated skeletal muscle cells, isolated mouse muscles and transgenic D. melanogaster lines will be used to investigate the role of Hippo signaling in BAG3-mediated muscle maintenance. The work should establish key mechanisms for the regulation of protein homeostasis in eukaryotes, relevant for our understanding of muscle weaknesses, neurodegeneration and cancer.

辅助伴侣 BAG3（BCL2 相关的 athanogene-3）是肌肉、免疫和神经元细胞中的关键蛋白稳态因子。此外，其过度表达有助于致癌转化。 BAG3 诱导伴侣辅助和泛素依赖性自噬途径，称为 CASA（伴侣辅助选择性自噬）。该途径介导非天然伴侣蛋白的溶酶体降解，例如肌动蛋白锚定蛋白纤丝蛋白在收缩肌肉和贴壁细胞中机械展开后的溶酶体降解。除了其降解诱导活性外，BAG3 还调节蛋白质合成。辅助伴侣与 Hippo 信号通路的成分相互作用以促进细丝蛋白的表达。 BAG3 介导的蛋白质降解和蛋白质合成的共同调节对于在机械应变下维持肌动蛋白细胞骨架至关重要。在这里，我们建议分析 Hippo 信号传导对 BAG3 功能和 CASA 活性的影响。该项目基于我们对与 BAG3 相关的多种 Hippo 激酶的鉴定。我们的初步数据表明，这些激酶中至少有一种直接控制平滑肌细胞中的 CASA 活性。我们将应用生化和细胞生物学测定来验证 Hippo 激酶与肌肉和神经元细胞中的 CASA 机制之间的功能相互作用。将进行磷酸化蛋白质组学来鉴定 CASA 成分中的 Hippo 磷酸化位点，并探讨它们对 BAG3 和 CASA 调节的重要性。最后，分化的骨骼肌细胞、分离的小鼠肌肉和转基因黑腹果蝇系将用于研究 Hippo 信号在 BAG3 介导的肌肉维持中的作用。这项工作应该建立真核生物中蛋白质稳态调节的关键机制，这与我们对肌肉无力、神经退行性变和癌症的理解相关。