Abstract:
The CXC-Chemokine Receptor Type 4, CXCR4 is a G-protein coupled receptor that helps regulate cell growth and division, differentiation, and migration. CXCR4 can be overexpressed when its trafficking to the lysosome is decreased. Overexpression of CXCR4 is associated with metastasis in cancer and promotes HIV infection. When bound to its CXCL12, CXCR4 is ubiquitylated and downregulated via endocytosis. At the early endosomes, CXCR4 is ubiquitylated by the ubiquitin ligase ITCH and then sorted into multivesicular bodies by the ubiquitin adaptor proteins Hrs and Tsg101. Degradation of CXCR4 occurs in the lysosomes. This project is interested in whether Secretory Carrier Membrane Protein (SCAMP) 3, which interacts with Hrs and Tsg101, regulates CXCR4 trafficking. RNA interference will be used to knockdown SCAMP3 and CXCR4,s localization relative to markers of the early endosome and lysosomes will be monitored through indirect immunofluorescence. Control immunofluorescence assays were performed with pulse chase time of 5, 15, 30, and 60 minutes to examine CXCR4 localization. We have found that CXCR4 accumulates in large compartments, indicative of lysosomes at 60 minutes or later. We are currently working to optimize the assay to accurately measure colocalization with both endosomal and lysosomal markers.
Team Members
Catalina Ordoñez Siza | (Quyen Aoh) | Gannon University
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