Effects of huperzine A on amyloid precursor protein processing and beta-amyloid generation in human embryonic kidney 293 APP Swedish mutant cells.
The amyloid precursor protein (APP) is cleaved enzymatically by nonamyloidogenic and amyloidogenic pathways. alpha-Secretase (alpha-secretase), cleaves APP within the beta-amyloid (Abeta) sequence, resulting in the release of a secreted fragment of APP (alphaAPPs) and precluding Abeta generation. In this study, we investigated the effects of an acetylcholinesterase inhibitor, huperzine A (Hup A), on APP processing and Abeta generation in human embryonic kidney 293 cells transfected with human APP bearing the Swedish mutation (HEK293 APPsw). Hup A dose dependently (0-10 microM) increased alphaAPPs release and membrane-coupled APP CTF-C83, suggesting increased APP metabolism toward the nonamyloidogenic alpha-secretase pathway. The metalloprotease inhibitor TAPI-2 inhibited the Hup A-induced increase in alphaAPPs release, further suggesting a modulatory effect of Hup A on alpha-secretase activity. The synthesis of full-length APP and cell viability were unchanged after Hup A incubation, whereas the level of Abeta(Total) was significantly decreased, suggesting an inhibitory effect of Hup A on Abeta production. Hup A-induced alphaAPPs release was significantly reduced by the protein kinase C (PKC) inhibitors GF109203X and Calphostin C. These data, together with the finding that the PKCalpha level was enhanced prior to the increase of alphaAPPs secretion, indicate that PKC may be involved in Hup A-induced alphaAPPs secretion by HEK293 APPsw cells. Our data suggest alternative pharmacological mechanisms of Hup A relevant to the treatment of Alzheimer's disease.
Peng
Ying
Y
Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Jiang
Liying
L
Lee
David Y W
DY
Schachter
Steven C
SC
Ma
Zhongze
Z
Lemere
Cynthia A
CA
D000470:Alkaloids; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western / Q000379:methods; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*; D013997:Time Factors
D000470:Alkaloids; D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D018696:Neuroprotective Agents; D012717:Sesquiterpenes; C099410:TAPI-2; C050426:huperzine A; D051571:Protein Kinase C-alpha; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human