title: Gamma-secretase activity of presenilin 1 regulates acetylcholine muscarinic receptor-mediated signal transduction.
abstract: Familial Alzheimer's disease (FAD) presenilin 1 (PS1) mutations give enhanced calcium responses upon different stimuli, attenuated capacitative calcium entry, an increased sensitivity of cells to undergo apoptosis, and increased gamma-secretase activity. We previously showed that the FAD mutation causing an exon 9 deletion in PS1 results in enhanced basal phospholipase C (PLC) activity (Cedazo-Minguez, A., Popescu, B. O., Ankarcrona, M., Nishimura, T., and Cowburn, R. F. (2002) J. Biol. Chem. 277, 36646-36655). To further elucidate the mechanisms by which PS1 interferes with PLC-calcium signaling, we studied the effect of two other FAD PS1 mutants (M146V and L250S) and two dominant negative PS1 mutants (D257A and D385N) on basal and carbachol-stimulated phosphoinositide (PI) hydrolysis and intracellular calcium concentrations ([Ca2+]i) in SH-SY5Y neuroblastoma cells. We found a significant increase in basal PI hydrolysis in PS1 M146V cells but not in PS1 L250S cells. Both PS1 M146V and PS1 L250S cells showed a significant increase in carbachol-induced [Ca2+]i as compared with nontransfected or wild type PS1 transfected cells. The elevated carbachol-induced [Ca2+]i signals were reversed by the PLC inhibitor neomycin, the ryanodine receptor antagonist dantrolene, the general aspartyl protease inhibitor pepstatin A, and the specific gamma-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester. The cells expressing either PS1 D257A or PS1 D385N had attenuated carbachol-stimulated PI hydrolysis and [Ca2+]i responses. In nontransfected or PS1 wild type transfected cells, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester and pepstatin A also attenuated both carbachol-stimulated PI hydrolysis and [Ca2+]i responses to levels found in PS1 D257A or PS1 D385N dominant negative cells. Our findings suggest that PS1 can regulate PLC activity and that this function is gamma-secretase activity-dependent.
authors: Section of Experimental Geriatrics, Karolinska Institutet, Neurotec Department, Kliniskt Forskningscentrum, Novum, 141 86 Huddinge, Sweden.
authors: Bogdan O
authors: BO
authors: Popescu
authors: Angel
authors: A
authors: Cedazo-Minguez
authors: Eirikur
authors: E
authors: Benedikz
authors: Takeshi
authors: T
authors: Nishimura
authors: Bengt
authors: B
authors: Winblad
authors: Maria
authors: M
authors: Ankarcrona
authors: Richard F
authors: RF
authors: Cowburn
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000378:metabolism; D003620:Dantrolene / Q000494:pharmacology; D010450:Endopeptidases / Q000378:metabolism*; D005091:Exons; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006801:Humans; D006868:Hydrolysis; D015151:Immunoblotting; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009154:Mutation; D009355:Neomycin / Q000494:pharmacology; D053764:Presenilin-1; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D008565:Membrane Proteins; D009125:Muscle Relaxants, Central; C508853:PSEN1 protein, human; D053764:Presenilin-1; D011976:Receptors, Muscarinic; D002217:Carbachol; D010738:Type C Phospholipases; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; D003620:Dantrolene; D009355:Neomycin; D002118:Calcium