Secretome protein enrichment identifies physiological BACE1 protease substrates in neurons.
Cell surface proteolysis is essential for communication between cells and results in the shedding of membrane-protein ectodomains. However, physiological substrates of the contributing proteases are largely unknown. We developed the secretome protein enrichment with click sugars (SPECS) method, which allows proteome-wide identification of shedding substrates and secreted proteins from primary cells, even in the presence of serum proteins. SPECS combines metabolic glycan labelling and click chemistry-mediated biotinylation and distinguishes between cellular and serum proteins. SPECS identified 34, mostly novel substrates of the Alzheimer protease BACE1 in primary neurons, making BACE1 a major sheddase in the nervous system. Selected BACE1 substrates-seizure-protein 6, L1, CHL1 and contactin-2-were validated in brains of BACE1 inhibitor-treated and BACE1 knock-out mice. For some substrates, BACE1 was the major sheddase, whereas for other substrates additional proteases contributed to total substrate shedding. The new substrates point to a central function of BACE1 in neurite outgrowth and synapse formation. SPECS is also suitable for quantitative secretome analyses of primary cells and may be used for the discovery of biomarkers secreted from tumour or stem cells.
DZNE-German Center for Neurodegenerative Diseases, Munich, Germany.
Peer-Hendrik
PH
Kuhn
Katarzyna
K
Koroniak
Sebastian
S
Hogl
Alessio
A
Colombo
Ulrike
U
Zeitschel
Michael
M
Willem
Christiane
C
Volbracht
Ute
U
Schepers
Axel
A
Imhof
Albrecht
A
Hoffmeister
Christian
C
Haass
Steffen
S
Roßner
Stefan
S
Bräse
Stefan F
SF
Lichtenthaler
D053829:Amyloid Precursor Protein Secretases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism*; D013379:Substrate Specificity; D013569:Synapses / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse