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  • The Phosphoinositide Kinase PIKfyve Promotes Cathepsin-S-Mediated Major Histocompatibility Complex Class II Antigen Presentation.

The Phosphoinositide Kinase PIKfyve Promotes Cathepsin-S-Mediated Major Histocompatibility Complex Class II Antigen Presentation.

iScience (2019-01-07)
Maksim V Baranov, Frans Bianchi, Anastasiya Schirmacher, Melissa A C van Aart, Sjors Maassen, Elke M Muntjewerff, Ilse Dingjan, Martin Ter Beest, Martijn Verdoes, Samantha G L Keyser, Carolyn R Bertozzi, Ulf Diederichsen, Geert van den Bogaart
ABSTRACT

Antigen presentation to T cells in major histocompatibility complex class II (MHC class II) requires the conversion of early endo/phagosomes into lysosomes by a process called maturation. Maturation is driven by the phosphoinositide kinase PIKfyve. Blocking PIKfyve activity by small molecule inhibitors caused a delay in the conversion of phagosomes into lysosomes and in phagosomal acidification, whereas production of reactive oxygen species (ROS) increased. Elevated ROS resulted in reduced activity of cathepsin S and B, but not X, causing a proteolytic defect of MHC class II chaperone invariant chain Ii processing. We developed a novel universal MHC class II presentation assay based on a bio-orthogonal "clickable" antigen and showed that MHC class II presentation was disrupted by the inhibition of PIKfyve, which in turn resulted in reduced activation of CD4+ T cells. Our results demonstrate a key role of PIKfyve in the processing and presentation of antigens, which should be taken into consideration when targeting PIKfyve in autoimmune disease and cancer.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-Cathepsin B (Ab-1) Mouse mAb (CA10), lyophilized, clone CA10, Calbiochem®
Sigma-Aldrich
Anti-LAMP1 antibody produced in rabbit, affinity isolated antibody, buffered aqueous solution