Itchy, a Nedd4 Ubiquitin Ligase, Downregulates Latent Membrane Protein 2A Activity in B-Cell Signaling

AUTOR(ES)

Ikeda, Akiko

FONTE

American Society for Microbiology

RESUMO

Nedd4 family ubiquitin protein ligases (E3s) specifically associate with latent membrane protein 2A (LMP2A) of Epstein-Barr virus. Our previous studies analyzing LMP2A function in vitro have suggested that Nedd4 family E3s regulate LMP2A function. To determine the role of Nedd4 family E3s in LMP2A B-cell signaling, LMP2A transgenic (LMP2A+) mice were crossed with mice with the Itch-deficient (Itch−/−) background. Itchy, a mouse homologue of human AIP4, is a Nedd4 family E3 and is also the most abundant Nedd4 family E3 found in LMP2A affinity precipitates from B cells. There were significantly fewer B-cell receptor-positive B cells in spleen and bone marrow B cells in LMP2A+ Itch−/− mice than in LMP2A+ mice. In addition, LMP2A+ Itch−/− bone marrow B cells formed larger colonies in cultures treated with interleukin-7 (IL-7) than control bone marrow B cells did. Finally, there was a dramatic increase in tyrosine phosphorylation of LMP2A and Syk in IL-7-cultured LMP2A+ Itch−/− B cells. These results indicate that Nedd4 family E3s, in particular Itchy, downmodulate LMP2A activity in B-cell signaling.

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