γ2-Adaptin is functioning in the late endosomal sorting pathway and interacts with ESCRT-I and -III subunits.
γ2-Adaptin is a clathrin adaptor-related protein with unclear physiological function. Previous studies indicated that γ2-adaptin might act within the multivesicular body (MVB) protein-sorting pathway that is central to receptor down-regulation, lysosome biogenesis, and budding of enveloped viruses. Here, we have analyzed the effects of excess and deficit γ2-adaptin on exogenous and endogenous MVB cargoes and on the MVB machinery itself. Foreign cargoes, like retroviral Gags, are entrapped by overexpressed γ2-adaptin in detergent-insoluble polymers and blocked in budding. When viral budding involves MVB/endosomal structures, excess γ2-adaptin acts by accelerating lysosomal Gag destruction. Consistently, depletion of γ2-adaptin avoids Gag routing to the lysosome and increases viral production. Functional studies with natural MVB cargoes support a role of γ2-adaptin in MVB-to-lysosome transition. Furthermore, we show that different members of the endosomal sorting complex required for transport (ESCRT) that drive sorting from endosomes to lysosomes are sequestered upon γ2-adaptin overexpression. If sequestered irreversibly, they are targeted to enhanced lysosomal degradation. The participation of γ2-adaptin in MVB sorting is further suggested by our finding that it specifically interacts with the ESCRT subunits Vps28 and CHMP2A. These observations identify γ2-adaptin as a critical factor in MVB trafficking, which likely is involved in endosome-to-lysosome maturation.
Döring
Tatjana
T
Department of Medicine Microbiology and Hygiene, Universitätsmedizin der Johannes Gutenberg-Universität Mainz, Augustusplatz, Mainz, Germany.
Gotthardt
Katherina
K
Stieler
Jens
J
Prange
Reinhild
R
D033982:Adaptor Protein Complex gamma Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008856:Microscopy, Fluorescence; D057146:Multivesicular Bodies / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D034622:RNA Interference; D012190:Retroviridae / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection
D033982:Adaptor Protein Complex gamma Subunits; D014408:Biomarkers, Tumor; C507674:CHMP2A protein, human; D056827:Endosomal Sorting Complexes Required for Transport; D015683:Gene Products, gag; D008164:Luminescent Proteins; C476409:VPS28 protein, human