CD69 in resting and activated T lymphocytes. Its association with a GTP binding protein and biochemical requirements for its expression.
CD69 is a phosphorylated disulfide-linked homodimer that appears on the surface of human T, B cells and thymocytes in the early steps of activation; its molecular mass is 28 to 34 kDa under reducing conditions. This molecule is able to mediate positive signals to the lymphocytes as the anti-CD69 mAb (MLR3, AIM, Leu 23) in synergism with phorbol esters induce IL-2 production and proliferation of lymphocytes. Here we show that this molecule is associated to a GTP binding protein that is a substrate for Bordetella pertussis toxin. The relevance of CD69 in the activation process is also suggested by the broad range of signals able to modulate CD69 on T cells. In fact, not only the mitogens or the CD3-promoted activation, but also the alternative pathways mediated by CD2 or CD28 are accompanied by CD69 expression; moreover a very rapid and transient appearance of CD69 on the cell surface is observed also in response to a stimulus not specifically involved in T cell activation such as heat shock. Finally we demonstrate that CD69 is present in the cytoplasm of nonactivated T cells; accordingly its surface expression at the onset of activation is independent on a new RNA or protein synthesis.
Risso
A
A
Istituto Scientifico Tumori, Genova, Italy.
Smilovich
D
D
Capra
M C
MC
Baldissarro
I
I
Yan
G
G
Bargellesi
A
A
Cosulich
M E
ME
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D015703:Antigens, CD / Q000032:analysis* / Q000502:physiology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000502:physiology; D018106:CD28 Antigens; D002478:Cells, Cultured; D003593:Cytoplasm / Q000276:immunology; D019204:GTP-Binding Proteins / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000502:physiology; D012313:RNA / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000099192:CD69 Antigens
D000246:Adenosine Diphosphate Ribose; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D019204:GTP-Binding Proteins; D037181:Lectins, C-Type; D011493:Protein Kinase C; D012313:RNA; D013755:Tetradecanoylphorbol Acetate; D000099192:CD69 Antigens