The human cytomegalovirus glycoprotein UL16 traffics through the plasma membrane and the nuclear envelope.
The human cytomegalovirus (HCMV) UL16 gene encodes a glycoprotein that interferes with the immune response to the virus-infected cell. In vitro, UL16 interacts with MICB and ULBPs that are ligands for the stimulatory receptor NKG2D, expressed on NK cells and CD8(+)T cells. UL16 expression has been shown to promote intracellular accumulation of MICB, ULBP1 and 2 and thus, interfere with the immune response to HCMV-infected cells. The mechanism that has been suggested for UL16-mediated MICB downmodulation is retention in the ER. Here, we studied the intracellular localization and maturation of UL16 and MICB in HCMV-infected cells and transfectant systems. UL16 trafficked through the ER, TGN and progressed to the plasma membrane, after which the protein was internalized. Strikingly, UL16 was also observed in the inner nuclear membrane. MICB was also localized in the TGN in HCMV-infected cells. These data suggest that MICB trafficking might be affected after its transit through the ER.
Valés-Gómez
Mar
M
Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK. mv231@mole.bio.cam.ac.uk
Winterhalter
Adam
A
Roda-Navarro
Pedro
P
Zimmermann
Albert
A
Boyle
Louise
L
Hengel
Hartmut
H
Brooks
Andrew
A
Reyburn
Hugh T
HT
D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D003587:Cytomegalovirus / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D009685:Nuclear Envelope / Q000378:metabolism*; D021381:Protein Transport; D014764:Viral Proteins / Q000276:immunology / Q000378:metabolism*
D006023:Glycoproteins; D015395:Histocompatibility Antigens Class I; C098080:MICB antigen; D014764:Viral Proteins