Molecular analysis of CD26-mediated signal transduction in T cells

CD26 or dipeptidylpeptidase IV (DPP IV) is a cell surface protease involved in T cell activation. It is a type II transmembrane glycoprotein consistin g of a large extracellular part, a single transmembrane region and a short cytoplasmic tail without any common signalling motifs. To eluciate the mech anisms involved in CD26-mediated signalling we have constructed C-terminal deletion mutants of the human CD26 molecule and transfected them into murin e T cell hybridomas. Stimulation experiments show that most of the extracel lular part of CD26 can he deleted without affecting its costimulatory activ ity. Thr membrane proximal glycosylation rich region of CD26 is sufficient to transduce costimulatory signals. Activation of T cells via CD26, however , is not mediated by the important T cell receptor associated adaptor prote ins LAT and TRIM as shown in colocalization assays. (C) 2000 Elsevier Scien ce B.V. All rights reserved.