title: Novel regulation of MHC class II function in B cells.
abstract: The presence of post-translational regulation of MHC class II (MHC II) under physiological conditions has been demonstrated recently in dendritic cells (DCs) that potently function as antigen-presenting cells (APCs). Here, we report that MARCH-I, an E3 ubiquitin ligase, plays a pivotal role in the post-translational regulation of MHC II in B cells. MARCH-I expression was particularly high in B cells, and the forced expression of MARCH-I induced the ubiquitination of MHC II. In B cells from MARCH-I-deficient mice (MARCH-I KO), the half-life of surface MHC II was prolonged and the ubiquitinated form of MHC II completely disappeared. In addition, MARCH-I-deficient B cells highly expressed exogenous antigen-loaded MHC II on their surface and showed high ability to present exogenous antigens. These results suggest that the function of MHC II in B cells is regulated through ubiquitination by MARCH-I.
authors.affiliation: Laboratory for Infectious Immunity, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Matsuki
authors.forename: Mari
authors.initials: M
authors.lastname: Ohmura-Hoshino
authors.forename: Eiji
authors.initials: E
authors.lastname: Goto
authors.forename: Masami
authors.initials: M
authors.lastname: Aoki
authors.forename: Mari
authors.initials: M
authors.lastname: Mito-Yoshida
authors.forename: Mika
authors.initials: M
authors.lastname: Uematsu
authors.forename: Takanori
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Koseki
authors.forename: Osamu
authors.initials: O
authors.lastname: Ohara
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakayama
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.forename: Ken
authors.initials: K
authors.lastname: Matsuoka
authors.forename: Hak
authors.initials: H
authors.lastname: Hotta
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishido
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D053595:Embryonic Stem Cells; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D011499:Protein Processing, Post-Translational / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044767:Ubiquitin-Protein Ligases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000949:Histocompatibility Antigens Class II; C545340:MARCH1 protein, mouse; D044767:Ubiquitin-Protein Ligases