Autophagy
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Restoration of BECN1/Beclin 1-dependent autophagy and depletion of SQSTM1/p62 by genetic manipulation or autophagy-stimulatory proteostasis regulators, such as cystamine, have positive effects on mouse models of human cystic fibrosis (CF). These measures rescue the functional expression of the most frequent pathogenic CFTR mutant, F508del, at the respiratory epithelial surface and reduce lung inflammation in Cftr(F508del) homozygous mice. Cysteamine, the reduced form of cystamine, is an FDA-approved drug. ⋯ Importantly, this cysteamine effect after washout was further sustained by the sequential administration of epigallocatechin gallate (EGCG), a green tea flavonoid, both in vivo, in mice, and in vitro, in primary epithelial cells from CF patients. In a pilot clinical trial involving 10 F508del-CFTR homozygous CF patients, the combination of cysteamine and EGCG restored BECN1, reduced SQSTM1 levels and improved CFTR function from nasal epithelial cells in vivo, correlating with a decrease of chloride concentrations in sweat, as well as with a reduction of the abundance of TNF/TNF-alpha (tumor necrosis factor) and CXCL8 (chemokine [C-X-C motif] ligand 8) transcripts in nasal brushing and TNF and CXCL8 protein levels in the sputum. Altogether, these results suggest that optimal schedules of cysteamine plus EGCG might be used for the treatment of CF caused by the F508del-CFTR mutation.
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Dysregulation of autophagy contributes to neuronal cell death in several neurodegenerative and lysosomal storage diseases. Markers of autophagy are also increased after traumatic brain injury (TBI), but its mechanisms and function are not known. Following controlled cortical impact (CCI) brain injury in GFP-Lc3 (green fluorescent protein-LC3) transgenic mice, we observed accumulation of autophagosomes in ipsilateral cortex and hippocampus between 1 and 7 d. ⋯ This was accompanied by appearance of SQSTM1 and ubiquitin-positive puncta in the affected cells, suggesting that, similar to the situation observed in neurodegenerative diseases, impaired autophagy may contribute to neuronal injury. Consistently, GFP-LC3 and SQSTM1 colocalized with markers of both caspase-dependent and caspase-independent cell death in neuronal cells proximal to the injury site. Taken together, our data indicated for the first time that autophagic clearance is impaired early after TBI due to lysosomal dysfunction, and correlates with neuronal cell death.