Transmembrane signaling through B cell MHC class II molecules: anti-Ia antibodies induce protein kinase C translocation to the nuclear fraction.
Among receptors of immunologic importance, antigen receptors on B cells (mIg) and T cells (Ti/T3), as well as receptors for IL 2 and IL 3, appear to utilize a transmembrane signal transduction mechanism that involves protein kinase C (PKC) translocation from the cytosol to the plasma membrane. Here we report evidence that B cell surface type II major histocompatibility molecules (I-A and I-E) can act as signal transducing molecules, as evidenced by the ability of soluble ligands that bind these molecules to stimulate rapid translocation (less than 2 min) of cytosolic PKC. This phenomenon differs qualitatively from translocation induced by anti-Ig antibodies and all other ligands thus far studied, in involving an apparent translocation of protein kinase C to the nucleus. Data suggest that I-A/E molecules may play an active role in T cell-dependent B cell activation. They also provide an explanation for the previously observed suppressive effects of soluble I-A and I-E binding ligands on B cell activation in demonstrating that these ligands (anti-IA/E) deplete the cytosolic reservoir of PKC normally translocated to the plasma membrane after anti-Ig or LPS stimulation.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000502:physiology*; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D007072:Immunoglobulin D / Q000276:immunology; D007518:Isoantibodies / Q000276:immunology; D051379:Mice; D008861:Microsomes / Q000201:enzymology; D011493:Protein Kinase C / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D011971:Receptors, Immunologic / Q000502:physiology*; D013997:Time Factors
D000888:Antibodies, Anti-Idiotypic; D000949:Histocompatibility Antigens Class II; D007072:Immunoglobulin D; D007518:Isoantibodies; D011947:Receptors, Antigen, B-Cell; D011971:Receptors, Immunologic; D011493:Protein Kinase C