Multiple effects of aspartate mutant presenilin 1 on the processing and trafficking of amyloid precursor protein.
PS1 deficiency and expression of PS1 with substitutions of two conserved transmembrane aspartate residues ("PS1 aspartate variants") leads to the reduction of Abeta peptide secretion and the accumulation of amyloid precursor protein (APP) C-terminal fragments. To define the nature of the "dominant negative" effect of the PS1 aspartate variants, we stably expressed PS1 harboring aspartate to alanine substitutions at codons 257 (D257A) or 385 (D385A), singly or in combination (D257A/D385A), in mouse neuroblastoma, N2a cells. Expression of the PS1 aspartate variants resulted in marked accumulation of intracellular and cell surface APP C-terminal fragments. While expression of the D385A PS1 variant reduced the levels of secreted Abeta peptides, we now show that neither the PS1 D257A nor D257A/D385A variants impair Abeta production. Surprisingly, the stability of both immature and mature forms of APP is dramatically elevated in cells expressing PS1 aspartate variants, commensurate with an increase in the cell surface levels of APP. These findings lead us to conclude that the stability and trafficking of APP can be profoundly modulated by coexpression of PS1 with mutations at aspartate 257 and aspartate 385.
Kim
S H
SH
Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637, USA.
Leem
J Y
JY
Lah
J J
JJ
Slunt
H H
HH
Levey
A I
AI
Thinakaran
G
G
Sisodia
S S
SS
D000409:Alanine / Q000737:chemistry; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry*; D016282:Aspartic Acid Endopeptidases; D019921:Biotinylation; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003062:Codon; D018076:DNA, Complementary / Q000378:metabolism; D010450:Endopeptidases / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics*; D051379:Mice; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D011233:Precipitin Tests; D053764:Presenilin-1; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D016564:Amyloid beta-Protein Precursor; D003062:Codon; D018076:DNA, Complementary; D008565:Membrane Proteins; D010455:Peptides; D053764:Presenilin-1; D001224:Aspartic Acid; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse; D000409:Alanine