| First Author | Hauser JT | Year | 2014 |
| Journal | J Leukoc Biol | Volume | 96 |
| Issue | 5 | Pages | 843-55 |
| PubMed ID | 25024398 | Mgi Jnum | J:220136 |
| Mgi Id | MGI:5632273 | Doi | 10.1189/jlb.2A0713-353R |
| Citation | Hauser JT, et al. (2014) Coalescence of B cell receptor and invariant chain MHC II in a raft-like membrane domain. J Leukoc Biol 96(5):843-55 |
| abstractText | The BCR binds antigen for processing and subsequent presentation on MHC II molecules. Polyvalent antigen induces BCR clustering and targeting to endocytic processing compartments, which are also accessed by Ii-MHC II. Here, we report that clustered BCR is able to team up with Ii-MHC II already at the plasma membrane of mouse B-lymphocytes. Colocalization of BCR and Ii-MHC II on the cell surface required clustering of both types of molecules. The clustering of only one type did not trigger the recruitment of the other. Ii-bound MIF (a ligand of Ii) also colocalized with clustered BCR upon oligomerization of MIF on the surface of the B cell. Abundant surface molecules, such as B220 or TfnR, did not cocluster with the BCR. Some membrane raft-associated molecules, such as peptide-loaded MHC II, coclustered with the BCR, whereas others, such as GM1, did not. The formation of a BCR- and Ii-MHC II-containing membrane domain by antibody-mediated clustering was independent of F-actin and led to the coendocytosis of its constituents. With a rapid Brij 98 extraction method, it was possible to capture this membrane domain biochemically as a DRM. Ii and clustered BCR were present on the same DRM, as shown by immunoisolation. The coalescence of BCR and Ii-MHC II increased tyrosine phosphorylation, indicative of enhanced BCR signaling. Our work suggests a novel role for MIF and Ii-MHC II in BCR-mediated antigen processing. |
