A cytoplasmic motif in HLA-E that drives clathrin-mediated endocytosis and VCP-associated postendocytic trafficking.

He W., Damianou A., Vendrell I., Früh K., Yin DI., Brodsky FM., Kessler BM., Brackenridge S., Borrow P., Gillespie GM., McMichael AJ.

Human Leukocyte Antigen E (HLA-E) is a nonclassical MHC class I molecule that exhibits dual immunological functions in regulating natural killer (NK) cells and T cells through unusual trafficking patterns. We previously reported that HLA-E surface expression is low and transient due to its cytoplasmic tail and dominant VL9 peptide, making it a dynamic indicator of cellular status for NK cell surveillance. Here, we identify a sequence motif in the HLA-E cytoplasmic tail that enables rapid internalization via clathrin-mediated endocytosis (CME) through interaction with the adaptor protein 2 (AP-2) complex. Following internalization, HLA-E is routed to endosomes, where the same cytoplasmic motif and peptide loading together facilitate its reappearance on the cell surface-a process influenced by valosin-containing protein (VCP). Our findings reveal previously unrecognized endosomal trafficking pathways and regulatory mechanisms that distinguish HLA-E from classical HLA class I molecules, with broad implications for understanding the immunoregulatory roles of HLA-E.

DOI

10.1073/pnas.2514956122

Type

Journal article

Publication Date

2025-10-01T00:00:00+00:00

Volume

122

Addresses

Center for Immuno-Oncology, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom.

Keywords

Killer Cells, Natural, Cytoplasm, Endosomes, Humans, Adaptor Protein Complex 2, Clathrin, Histocompatibility Antigens Class I, Endocytosis, Amino Acid Motifs, Protein Transport, HEK293 Cells, Valosin Containing Protein, HLA-E Antigens

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