The tetraspanin CD9 mediates lateral association of MHC class II molecules on the dendritic cell surface

Abstract

antigen presentation ͉ major histocompatibility complex class II ͉ B cell ͉ CD81 ͉ costimulatory molecules

SCIMP, a Transmembrane Adaptor Protein Involved in Major Histocompatibility Complex Class II Signaling

“…MHC-II molecules loaded with specific antigenic peptides appear to be enriched in TEMs (30,47), and it has been suggested that TEMs might increase the chance of successful presentation of a limited pool of MHC-II molecules loaded with specific peptides. This would be in agreement with the observation that tetraspanins are constituents of IS (34).…”

MHC Class II Antigen Presentation by Dendritic Cells Regulated through Endosomal Sorting

“…Perhaps pMHCII uses the clathrinindependent carrier (GLIC)/GPI-AP-enriched early endosomal compartment (GEEC) pathway, an endocytosis route that is also used by lipid raft-associated molecules like GPI-linked proteins and cholera toxin B (Mayor and Pagano 2007;Howes et al 2010). Furthermore, tetraspanin-enriched microdomains have been implicated in clustering and routing of MHCII from the plasma membrane (Hammond et al 1998;Engering and Pieters 2001;Kropshofer et al 2002;Zilber et al 2005;Poloso et al 2006;Unternaehrer et al 2007). Tetraspanins belong to a family of proteins that span the membrane four times and are palmitoylated, a posttranslational modification that stimulates lateral partitioning into protein/lipid domains (Kovalenko et al 2004;Yáñez-Mó et al 2009).…”

Identification and characterization of the first reptilian CD9, and its expression analysis in response to bacterial infection

“…CD9 is such a tetraspanin that could provide co-stimulation to naive T lymphocytes and was preferentially expressed on the human CD4 + CD45RA + naive T cell subset and involved in T cell activation [7,8]. And it was selectively expressed in DCs and necessary for the association of heterologous MHC-II and facilitated the formation of MHC-II multimers expected to enhance TCR stimulation by DCs [9].…”