endosomallysosomal

Endosomallysosomal is a term used to describe the cellular system that encompasses endosomes and lysosomes, together with the pathways that connect them. It refers to the maturation, trafficking, and degradation of materials internalized by the cell, as well as the turnover of membrane and soluble components. The endosomallysosomal system functions as a central hub for nutrient sensing, signaling, and quality control.

Endosomes arise from endocytosis. Early endosomes act as sorting stations, retaining or recycling cargo; they mature into late endosomes, which progress toward lysosomes. Lysosomes host acidic hydrolases and act as the endpoint of degradation. The maturation and fusion of these compartments are controlled by Rab GTPases, SNAREs, and tethering factors, and by the proton-pumping activity of V-ATPases that lower organelle pH.

Key processes associated with the endosomallysosomal system include endocytosis, endosome maturation, lysosome biogenesis, autophagy, and phagosome-lysosome fusion. The ESCRT machinery sorts ubiquitinated membrane proteins into intraluminal vesicles, aiding degradation. The system also participates in antigen processing, receptor downregulation, and lipid recycling.

Dysfunction of the endosomallysosomal axis is linked to human diseases, notably lysosomal storage disorders and neurodegenerative diseases. Research focuses on understanding trafficking defects, improving delivery of therapeutics to lysosomes, and targeting endolysosomal pathways in disease.