Project Details
Projekt
Regulation of the human proteostasis network under mitochondrial protein import stress
Subject Area
Biochemistry
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 541758684
Mitochondria play a vital role in human metabolism, and their well-functioning is required to keep the cellular proteostasis network in balance. Here, a key aspect is that most mitochondrial proteins are nucleus-encoded and synthesized as precursor proteins at cytosolic ribosomes. Thus, cytosolic protein synthesis is inevitably linked to functional precursor import pathways into mitochondria, and these processes are closely monitored by mitochondria quality control mechanisms and the proteasome. Previous work showed that impaired mitochondrial import leads to accumulation and aggregation of precursors in the cytosol, which provokes cellular defects that eventually lead to human disorders. To counteract mitochondrial precursor accumulation, cytosolic protein synthesis requires reprogramming. Moreover, the proteasome is activated for efficient degradation of mislocalized precursors, along with the removal of stalled precursors in mitochondrial translocases and induction of chaperone-assisted protein folding. However, how protein synthesis and proteasomal degradation are regulated during acute failure of the mitochondrial import system in human cells is still poorly understood. Our preliminary data suggest that intracellular signalling mechanisms involved in the fast regulation of the cytosolic translation machinery and proteasomes in response to acute mitochondrial precursor import stress in human cells. In this project, we will capitalize on the unique expertise of the research team to dissect the regulatory proteostasis network during acute mitochondrial import stress with altered cellular RNA expression, cytosolic protein synthesis, and proteasome activity using combined biochemical approaches and advanced proteomics technologies. In three interconnected work packages, we will first systematically investigate the human proteostasis network activated during acute import stress and establish different mitochondrial stress conditions, involving chemical treatments, siRNA applications or expression of clogger proteins. Second, we will delineate site-specific changes in the phosphorylation landscape of cytosolic ribosomes, which provide a posttranslational mechanism for fast adaptation of the translational program to maintain proteostasis during acute mitochondrial stress. Finally, we will identify the molecular nature of adaptive proteasome changes and whether they contribute to the resolution of mitochondrial import stress.
DFG Programme
Priority Programmes
