Inhibition of glutaminyl cyclase alters pyroglutamate formation in mammalian cells.
Mammalian cell lines were examined concerning their Glutaminyl Cyclase (QC) activity using a HPLC method. The enzyme activity was suppressed by a QC specific inhibitor in all homogenates. Aim of the study was to prove whether inhibition of QC modifies the posttranslational maturation of N-glutamine and N-glutamate peptide substrates. Therefore, the impact of QC-inhibition on amino-terminal pyroglutamate (pGlu) formation of the modified amyloid peptides Abeta(N3E-42) and Abeta(N3Q-42) was investigated. These amyloid-beta peptides were expressed as fusion proteins with either the pre-pro sequence of TRH, to be released by a prohormone convertase, or as engineered amyloid precursor protein for subsequent liberation of Abeta(N3Q-42) after beta- and gamma-secretase cleavage during posttranslational processing. Inhibition of QC leads in both expression systems to significantly reduced pGlu-formation of differently processed Abeta-peptides. This reveals the importance of QC-activity during cellular maturation of pGlu-containing peptides. Thus, QC-inhibition should impact bioactivity, stability or even toxicity of pyroglutamyl peptides preventing glutamine and glutamate cyclization.
Cynis
Holger
H
Probiodrug AG, Weinbergweg 22, 06120 Halle/Saale, Germany.
Schilling
Stephan
S
Bodnár
Mandy
M
Hoffmann
Torsten
T
Heiser
Ulrich
U
Saido
Takaomi C
TC
Demuth
Hans-Ulrich
HU
D019881:Aminoacyltransferases / Q000032:analysis / Q000037:antagonists & inhibitors*; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D051379:Mice; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000032:analysis / Q000378:metabolism*
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D019881:Aminoacyltransferases; C059280:glutaminyl-peptide cyclotransferase; D011761:Pyrrolidonecarboxylic Acid