title: The cell adhesion protein P-selectin glycoprotein ligand-1 is a substrate for the aspartyl protease BACE1.
abstract: The aspartyl protease BACE1 cleaves the amyloid precursor protein and the sialyltransferase ST6Gal I and is important in the pathogenesis of Alzheimer's disease. The normal function of BACE1 and additional physiological substrates have not been identified. Here we show that BACE1 acts on the P-selectin glycoprotein ligand 1 (PSGL-1), which mediates leukocyte adhesion in inflammatory reactions. In human monocytic U937 and human embryonic kidney 293 cells expressing endogenous or transfected BACE1, PSGL-1 was cleaved by BACE1 to generate a soluble ectodomain and a C-terminal transmembrane fragment. No evidence of the cleavage fragment was seen in primary cells derived from mice deficient in BACE1. By using deletion constructs and enzymatic deglycosylation of the C-terminal PSGL-1 fragments, the cleavage site in PSGL-1 was mapped to the juxtamembrane region within the ectodomain. In an in vitro assay BACE1 catalyzed the formation of the PSGL-1 products seen in vivo. The cleavage occurred at a Leu-Ser peptide bond as identified by mass spectrometry using a synthetic peptide. We conclude that PSGL-1 is an additional substrate for BACE1.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D017931:DNA Primers; D010450:Endopeptidases; D005091:Exons; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D017931:DNA Primers; D008562:Membrane Glycoproteins; C084882:P-selectin ligand protein; D011993:Recombinant Fusion Proteins; D000469:Alkaline Phosphatase; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human