title: Human immunodeficiency virus type 1 Vpu protein interacts with CD74 and modulates major histocompatibility complex class II presentation.
abstract: The human immunodeficiency virus type 1 (HIV-1) Vpu accessory protein is a transmembrane protein that down regulates CD4 expression and promotes the release of new virions. We screened a human leukocyte-specific yeast two-hybrid expression library to discover novel Vpu-interacting cellular proteins. The major histocompatibility complex class II (MHC II) invariant chain, also called Ii or CD74, was found to be one such protein. We show direct binding of Vpu and CD74 by using a yeast two-hybrid assay and coimmunoprecipitation from HIV-1-infected cells. The cytoplasmic region of Vpu was found to interact with the 30-amino-acid cytoplasmic tail of CD74. Human monocytic U937 cells infected with wild-type or Vpu-defective HIV-1 and transfected cells showed that Vpu down modulated the surface expression of mature MHC II molecules. The reduction in cell surface mature MHC II molecules correlated with decreased antigen presentation to T cells in culture. Thus, the Vpu protein also contributes to viral persistence by attenuating immune responses during HIV infection. This report further exemplifies the rich diversity and redundancy shown by HIV in immune evasion.
authors.affiliation: Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Amjad
authors.initials: A
authors.lastname: Hussain
authors.forename: Clement
authors.initials: C
authors.lastname: Wesley
authors.forename: Mohammad
authors.initials: M
authors.lastname: Khalid
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Chaudhry
authors.forename: Shahid
authors.initials: S
authors.lastname: Jameel
mesh_terms: D017951:Antigen Presentation / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D002460:Cell Line; D015497:HIV-1 / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D054298:Human Immunodeficiency Virus Proteins / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D009000:Monocytes / Q000821:virology; D011485:Protein Binding; D025941:Protein Interaction Mapping; D020798:Two-Hybrid System Techniques; D054334:Viral Regulatory and Accessory Proteins / Q000378:metabolism*; D000086082:Viroporin Proteins
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D054298:Human Immunodeficiency Virus Proteins; D054334:Viral Regulatory and Accessory Proteins; C045084:invariant chain; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins