Spinal Muscular Atrophy autophagy profile is tissue-dependent: differential regulation between muscle and motoneurons.
Alba SansaIvan HidalgoMaria P MirallesSandra de la FuenteM Jose Perez-GarciaFrancina MunellRosa M SolerAna GarceraPublished in: Acta neuropathologica communications (2021)
Spinal muscular atrophy (SMA) is a neuromuscular genetic disease caused by reduced survival motor neuron (SMN) protein. SMN is ubiquitous and deficient levels cause spinal cord motoneurons (MNs) degeneration and muscle atrophy. Nevertheless, the mechanism by which SMN reduction in muscle contributes to SMA disease is not fully understood. Therefore, studies evaluating atrophy mechanisms in SMA muscles will contribute to strengthening current knowledge of the pathology. Here we propose to evaluate autophagy in SMA muscle, a pathway altered in myotube atrophy. We analized autophagy proteins and mTOR in muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients and in gastrocnemius muscles from a severe SMA mouse model. Human MNs differentiated from SMA and unaffected control iPSCs were also included in the analysis of the autophagy. Muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients showed reduction of the autophagy marker LC3-II. In SMA mouse gastrocnemius, we observed lower levels of LC3-II, Beclin 1, and p62/SQSTM1 proteins at pre-symptomatic stage. mTOR phosphorylation at Ser2448 was decreased in SMA muscle cells. However, in mouse and human cultured SMA MNs mTOR phosphorylation and LC3-II levels were increased. These results suggest a differential regulation in SMA of the autophagy process in muscle cells and MNs. Opposite changes in autophagy proteins and mTOR phosphorylation between muscle cells and neurons were observed. These differences may reflect a specific response to SMN reduction, which could imply diverse tissue-dependent reactions to therapies that should be taken into account when treating SMA patients.
Keyphrases
- skeletal muscle
- cell death
- endoplasmic reticulum stress
- induced apoptosis
- end stage renal disease
- signaling pathway
- spinal cord
- oxidative stress
- cell cycle arrest
- newly diagnosed
- ejection fraction
- chronic kidney disease
- endothelial cells
- mouse model
- prognostic factors
- cell proliferation
- spinal cord injury
- peritoneal dialysis
- gene expression
- patient reported outcomes
- early onset
- genome wide
- neuropathic pain
- extracellular matrix
- pi k akt
- drug induced
- amino acid
- protein protein
- tandem mass spectrometry