endosome transport via multivesicular body sorting pathway

Definition

Target type: biologicalprocess

The directed movement of substances from endosomes to lysosomes or vacuoles by a pathway in which molecules are sorted into multivesicular bodies, which then fuse with the target compartment. [GOC:mah, PMID:12461556, PMID:16689637]

Endosome transport via the multivesicular body (MVB) sorting pathway is a crucial cellular process that enables the delivery of cargo molecules, including transmembrane proteins, lipids, and signaling molecules, to lysosomes for degradation or to other cellular compartments. This pathway plays a pivotal role in regulating a variety of cellular functions, such as signal transduction, immune response, and cellular homeostasis.

The process begins with the formation of early endosomes, small vesicles that bud off from the plasma membrane and engulf incoming cargo molecules. These early endosomes mature into late endosomes, which are characterized by the presence of intraluminal vesicles (ILVs). ILVs are small vesicles that bud from the limiting membrane of the late endosome, encapsulating selected cargo molecules within their lumen. The formation of ILVs is driven by the action of a specialized machinery, including the ESCRT (endosomal sorting complexes required for transport) proteins, which recognize and sort cargo molecules for inclusion in the ILVs.

The late endosome, now containing a population of ILVs, matures into a multivesicular body (MVB). MVBs can then fuse with either lysosomes, where the ILVs are released and their cargo molecules are degraded, or with other cellular compartments, such as the plasma membrane, allowing the release of the cargo molecules outside the cell.

The sorting of cargo molecules into the MVB pathway is tightly regulated and involves a complex interplay of factors, including:

- **Ubiquitination:** Many cargo molecules destined for degradation are tagged with ubiquitin, a small protein that acts as a signal for their inclusion in ILVs.
- **ESCRT proteins:** These proteins function as a molecular machinery that recognizes ubiquitinated cargo and mediates their sorting into ILVs.
- **Lipid composition:** The lipid composition of the endosome membrane influences the formation of ILVs and the recruitment of ESCRT proteins.
- **Rab GTPases:** These small GTPases regulate the trafficking of endosomes and MVBs along microtubules, ensuring efficient transport to their destinations.

The MVB sorting pathway is highly dynamic and interconnected with other cellular pathways, making it essential for maintaining cellular homeostasis. Disruptions in this pathway can lead to a variety of cellular defects and disease states. For example, impaired MVB sorting can contribute to neurodegenerative disorders, cancer, and infectious diseases.'
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Proteins (1)

Compounds (3)