title: Activity of alpha-secretase as the common final effector of protein kinase C-dependent and -independent modulation of amyloid precursor protein metabolism.
abstract: The metabolic fate of the amyloid precursor protein (APP) is one of the key factors in the pathogenesis of Alzheimer's disease (AD). A complex cellular mechanism regulates the rate at which the precursor is cleaved by alpha-secretase and released as soluble protein in the extracellular space. We show here that alpha-secretase constitutes the common final effector of several independent means of stimulation of soluble APP (sAPP) release. The release of sAPP by alpha-secretase resembles that of several other membrane-bound proteins with soluble counterparts, a process that is sensitive to matrix metalloprotease inhibitors. The hydroxamic acid-based compound KD-IX-73-4 inhibits phorbol ester-mediated sAPP release from COS cells with an IC50 of 8 microM, consistent with previous data for the same compound against leukocyte L-selectin shedding. Beyond direct protein kinase C (PKC) activation we show that KD-IX-73-4 inhibits also receptor-mediated sAPP release induced by carbachol in SH-SY5Y cells and by bradykinin in human skin fibroblasts, with the latter being a PKC-independent mechanism. Altogether these data suggest that all pharmacological means of stimulating sAPP release converge to a hydroxamic acid-based inhibitor-sensitive proteolytic enzyme. Moreover, because KD-IX-73-4 was effective in the inhibition of stimulated but not constitutive sAPP release, these data suggest the existence of different enzymes regulating the two metabolic pathways leading to sAPP secretion.
authors.affiliation: IRCCS Centro San Giovanni di Dio-FBF, Brescia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Racchi
authors.forename: D C
authors.initials: DC
authors.lastname: Solano
authors.forename: M
authors.initials: M
authors.lastname: Sironi
authors.forename: S
authors.initials: S
authors.lastname: Govoni
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D001920:Bradykinin / Q000494:pharmacology; D019556:COS Cells; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004151:Dipeptides / Q000494:pharmacology; D010450:Endopeptidases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D009447:Neuroblastoma; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012867:Skin / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D017077:Culture Media, Conditioned; D004151:Dipeptides; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; C099147:KD-IX 73-4; D015240:Phorbol 12,13-Dibutyrate; D002217:Carbachol; D011493:Protein Kinase C; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; D001920:Bradykinin