Protein homeostasis in skeletal muscle

Subproject Speakers                      
Berlin: Jens Fielitz, MD, PD
Paris:  Vincent Mouly, PhD

Patients with sepsis and immobilization often develop a life threatening muscular disorder called critical illness myopathy (CIM), which is characterized by a loss of myosin heavy chain (MHC). CIM prevents patients from being mobilized and enhances their morbidity and mortality. CIM is characterized by an activation of the protein degrading ubiquitin proteasome system (UPS) and its key E3 ubiquitin ligases Muscle RING-finger (MuRF) 1 and 3 that mediate degradation of structural proteins in the diseased skeletal muscle. This activation leads to a reduction in skeletal muscle function and skeletal muscle atrophy. Our previous work showed that MuRF1 and 3 specifically interact with, ubiquitinate, and mediate UPS-dependent degradation of structural proteins, most importantly MHC. Accordingly, mice deficient for MuRF1 and 3 developed a skeletal muscle myopathy characterized by subsarcolemmal MHC accumulation and diminished muscle performance. Our findings identified MuRF1 and 3 as key E3 ligases for the UPS-dependent turnover of MHC and revealed a potential basis for CIM. Inhibition of this pathway could be useful to prevent and treat CIM. However, the precise molecular mechanisms activating MuRF1 and 3 in CIM and its relevance for patients developing CIM are unclear. Furthermore, it is unclear which additional pathological pathways, beside inflammatory cytokines, are activated during sepsis leading to muscular wasting and CIM.

Theses in progress

Completed theses