Endogenous C-terminal fragments of beta-amyloid precursor protein from Xenopus laevis skin exudate.
Using a monoclonal antibody against the entire C-terminal end of human APP(695) (643-695 sequence) and a monoclonal antibody directed against human beta[1-40] amyloid peptide (betaA), we show the existence of endogenous peptides proteolytically derived from APP in skin exudate of the non transgenic Xenopus laevis frog. The majority of the immunoreactivity is found associated with a 30 kDa molecular species. Biochemical fractionation followed by mass spectrometry identification allowed us to assign this molecular species to C-terminal APP fragments containing all or part of betaA. According to the nature of N- and C-terminal amino acids we identified endogenous beta-, gamma-, epsilon-secretase-like activities, caspase-like activity and numerous endogenous cleavage sites within the beta-amyloid sequence at same sites as those observed in human betaA sequence. All these homologies with human indicate that X. laevis skin exudate is a good natural model to study betaA metabolism. In this way, interestingly, we identified endogenous cleavages at prohormone convertase-like sites not yet described at the same sites in human. Finally, all identified peptide fragments were stably associated with a 20.2 kDa protein. These new observed features suggest new research pathways concerning human betaA metabolism and carriage of hydrophobic peptide fragments issued from APP processing.
Clamagirand
Christine
C
Laboratoire de Biochimie des Signaux Régulateurs Cellulaires and Moléculaires, Université Pierre et Marie Curie-Paris6, FRE 2621 CNRS, 96 Bd Raspail, Paris, F-75006 France. clamag@ccr.jussieu.fr
El Abida
Boutaïna
B
Der Garabedian
P Arsene
PA
Hanquez
Chantal
C
Dubost
Lionel
L
Marie
Arul
A
Rholam
Mohamed
M
Friguet
Bertrand
B
Cohen
Paul
P
D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism*; D000818:Animals; D002850:Chromatography, Gel / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005122:Exudates and Transudates / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D043484:Proprotein Convertases / Q000378:metabolism; D020539:Sequence Analysis, Protein; D012867:Skin / Q000737:chemistry*; D029867:Xenopus Proteins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D014982:Xenopus laevis
D016564:Amyloid beta-Protein Precursor; D010446:Peptide Fragments; D029867:Xenopus Proteins; D043484:Proprotein Convertases