核酸を分解する膜透過型オートファジーのメカニズムと疾患との関連

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Because already known lysosomal degradation pathways cannot fully account for total levels of lysosomal proteolysis in cells (Tong et al. 2020) and protein accumulation in cells is a hallmark of neurodegenerative diseases, we sought for novel protein degradation pathways in lysosomes.We found that cytosolic proteins are imported into lysosomes by a direct uptake mechanism which is distinct from any known pathways, and then degraded. SIDT2 mediates the translocation and contributes conspicuously to the lysosomal degradation of a wide range of cytosolic proteins in cells at the constitutive level (nutrient-rich condition). We also identified a dominant-negative mutation in SIDT2 which causes familial neuropathy and distal myopathy with rimmed vacuoles in humans and confirmed that Sidt2 knockout mice recapitulate the typical features of the disease.These results reveal previously unknown pathway of proteolysis in lysosomes and highlight the importance of lysosomal degradation of proteins in human physiology and pathophysiology.