title: PEN-2 enhances gamma-cleavage after presenilin heterodimer formation.
abstract: The presenilin (PS) complex, including PS, nicastrin, APH-1 and PEN-2, is essential for gamma-secretase activity, which is required for amyloid beta-protein (Abeta) generation. However, the precise individual roles of the three cofactors in the PS complex in Abeta generation remain to be clarified. Here, to distinguish the roles of PS cofactors in gamma-secretase activity from those in PS endoproteolysis, we investigated their roles in the gamma-secretase activity reconstituted by the coexpression of PS N- and C-terminal fragments (NTF and CTF) in PS-null cells. We demonstrate that the coexpression of PS1 NTF and CTF forms the heterodimer and restores Abeta generation in PS-null cells. The generation of Abeta was saturable at a certain expression level of PS1 NTF/CTF, while the overexpression of PEN-2 alone resulted in a further increase in Abeta generation. Although PEN-2 did not enhance PS1 NTF/CTF heterodimer formation, PEN-2 expression reduced the IC50 of a specific gamma-secretase inhibitor, a transition state analogue, for Abeta generation, suggesting that PEN-2 expression enhances the affinity or the accessibility of the substrate to the catalytic site. Thus, our results strongly suggest that PEN-2 is not only an essential component of the gamma-secretase complex but also an enhancer of gamma-cleavage after PS heterodimer formation.
authors.affiliation: Department of Dementia Research, National Institute for Longevity Sciences, Morioka, Obu, Aichi, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Shiraishi
authors.forename: Xiaorei
authors.initials: X
authors.lastname: Sai
authors.forename: Hua-Qin
authors.initials: HQ
authors.lastname: Wang
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Maeda
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Kurono
authors.forename: Masaki
authors.initials: M
authors.lastname: Nishimura
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yanagisawa
authors.forename: Hiroto
authors.initials: H
authors.lastname: Komano
mesh_terms: D000409:Alanine / Q000235:genetics; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western / Q000379:methods; D002219:Carbamates / Q000494:pharmacology; D002460:Cell Line; D004151:Dipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005347:Fibroblasts; D005786:Gene Expression Regulation / Q000187:drug effects*; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology; D008565:Membrane Proteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D010446:Peptide Fragments / Q000378:metabolism; D053764:Presenilin-1; D053766:Presenilin-2; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism / Q000494:pharmacology; D011863:Radioimmunoassay / Q000379:methods; D018709:Statistics, Nonparametric; D019076:Transgenes; D014280:Triglycerides / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D002219:Carbamates; D004151:Dipeptides; D004791:Enzyme Inhibitors; C410009:L 685458; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C489428:Myc protein, mouse; D010446:Peptide Fragments; D053764:Presenilin-1; D053766:Presenilin-2; D016271:Proto-Oncogene Proteins c-myc; D014280:Triglycerides; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C413604:nicastrin protein; D001224:Aspartic Acid; D005680:gamma-Aminobutyric Acid; C057077:1,2-dilinolenoyl-3-(4-aminobutyryl)propane-1,2,3-triol; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse; D000409:Alanine