Modulation of inositol 1,4,5-triphosphate concentration by prolyl endopeptidase inhibition.
Prolyl endopeptidase (PEP) is a proline-specific oligopeptidase with a reported effect on learning and memory in different rat model systems. Using the astroglioma cell line U343, PEP expression was reduced by an antisense technique. Measuring different second-messenger concentrations revealed an inverse correlation between inositol 1,4,5-triphosphate [Ins(1,4,5)P3] concentration and PEP expression in the generated antisense cell lines. However, no effect on cAMP generation was observed. In addition, complete suppression of PEP activity by the specific inhibitor, Fmoc-Ala-Pyrr-CN (5 micro m) induced in U343 and other cell lines an enhanced, but delayed, increase in Ins(1,4,5)P3 concentration. This indicates that the proteolytic activity of PEP is responsible for the observed effect. Furthermore, the reduced PEP activity was found to amplify Substance P-mediated stimulation of Ins(1,4,5)P3. The effect of reduced PEP activity on second-messenger concentration indicates a novel intracellular function of this peptidase, which may have an impact on the reported cognitive enhancements due to PEP inhibition.
Schulz
Ingo
I
Probiodrug AG, Halle, Germany; Department of Molecular Biology and Cell Culture Technology, Mannheim University of Applied Sciences, Germany.
Gerhartz
Bernd
B
Neubauer
Antje
A
Holloschi
Andreas
A
Heiser
Ulrich
U
Hafner
Mathias
M
Demuth
Hans-Ulrich
HU
D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D000085822:Prolyl Oligopeptidases; D012697:Serine Endopeptidases / Q000187:drug effects*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction; D013373:Substance P / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D015842:Serine Proteinase Inhibitors; D013373:Substance P; D015544:Inositol 1,4,5-Trisphosphate; D012697:Serine Endopeptidases; C000705287:PREPL protein, human; D000085822:Prolyl Oligopeptidases