Characterization of Endocytosis in T cells

Wednesday, September 24, 2014 — Poster Session IV
10:00 a.m. –12:00 p.m.	FAES Academic Center	NHLBI	CELLBIO-5

Authors

• DL Johnson
• JM Wilson
• JG Donaldson

Abstract

We have characterized clathrin independent endocytosis in the human Jurkat T cell line and compared it with what has been reported in HeLa cells. MHCI is endocytosed separately from the transferrin receptor that enters cells by clathrin-mediated endocytosis. Then, MHCI passed through EEA1 endosomes, prior to trafficking to LAMP positive vesicles for degradation or they were recycled. In contrast, CD98 avoided EEA1 endosomes and was rapidly recycled. Plasma membrane proteins that entered the cell through clathrin independent mechanisms co-localized with the G protein Arf6. We have also shown that cycles of GTP-binding and hydrolysis on Arf6 are important for T cell activation. When Jurkat cells expressing the dominant negative mutant of Arf6 are mixed with an activated antigen presenting cell, the T cell does not form a proper immunological synapse. We are working to determine if Arf6 is important for T cell signaling and also its role in Jurkat cell spreading. Our results confirm that CIE and subsequent endosomal trafficking is a highly conserved process. The cycle of the G Protein Arf6 is also required for proper T cell conjugate formation. Our future goal is to understand how CIE and endosomal trafficking affects T cell signaling and function.

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