Article ID Journal Published Year Pages File Type
1928846 Biochemical and Biophysical Research Communications 2013 6 Pages PDF
Abstract

•LEDA-1/PIANP is expressed in neural tissues, LSEC and B16 melanoma cells.•Immune inhibitory receptor PILRα can be activated by LEDA-1/PIANP.•Processing of LEDA-1/PIANP includes glycosylation and proteolytic cleavage.•Proprotein convertase cleavage precedes membrane localisation of LEDA-1/PIANP.•Soluble fragments of LEDA-1/PIANP could thus be generated to bind distant receptors.

Liver endothelial differentiation-associated protein-1 (LEDA-1/PIANP) is a type-I-transmembrane protein first identified by us as a putative junctional protein in liver sinusoidal endothelial cells. Others have shown that LEDA-1/PIANP binds and activates immune inhibitory receptor PILRα in trans, a process that requires sialidation of LEDA-1/PIANP. Here we show that LEDA-1/PIANP is subject to O-glycosylation and sialidation as demonstrated in brain tissue as well as in LEDA-1 expressing cell lines by using anti-LEDA-1/PIANP C-terminal antibodies. In addition, analysis of LEDA-1/PIANP processing with His-tags inserted at different positions in the extracellular domain revealed that multiple steps of proteolytic cleavage occur during maturation of the protein. Proteolytic cleavage between aa59 and aa83 preceded sorting of the protein to the plasma membrane. Deletion of aa75–79 and inhibition with Furin inhibitor I confirmed that LEDA-1/PIANP is processed by a Furin-like proprotein convertase. In summary, these findings show that Furin-like proprotein convertase-dependent processing precedes plasma membrane localization of LEDA-1/PIANP that is a pre-requisite of functional receptor–ligand interactions in vitro and in vivo.

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