Effect of PS1 deficiency and an APP gamma-secretase inhibitor on Notch1 signaling in primary mammalian neurons.
Presenilin1 (PS1) has been implicated in normal Notch1 processing and signaling in several experimental systems. In the present study, the relationship between PS1 and Notch1 in mammalian neurons is studied by analyzing Notch1 cleavage and C-terminal nuclear translocation as well as Notch1 signaling via the transactivation of a CBF1-luciferase reporter construct. We show that full-length Notch1 [N1(FL)] transfected into wild type (WT) primary neurons is cleaved in the presence of its biological ligand Delta (Dl) and translocated to the nucleus within 1--3 min of ligand addition. PS1 deficient neurons show normal Notch1 insertion into the cellular membrane, yet lack Notch1 activation resulting in markedly inhibited nuclear translocation of the C-terminal Notch fragment (NICD). PS1 deficient neurons also have impaired Notch1 signaling which can be restored fully or partially to levels seen in WT littermates by transfection with WT or familial Alzheimer's disease-associated M146L mutant PS1, respectively. We also show that pharmacological inhibition of PS1-associated gamma-secretase activity parallels the effects of genetic PS1 deficiency in these assays. These results support the hypothesis that PS1 deficiency blocks neuronal Notch1 processing and signaling.
Alzheimer's Disease Research Laboratory, Department of Neurology, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
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Jack
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Berezovska
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Wolfe
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Hyman
D000544:Alzheimer Disease / Q000378:metabolism / Q000503:physiopathology; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D006624:Hippocampus / Q000166:cytology; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008156:Luciferases / Q000235:genetics; D008322:Mammals; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D009687:Nuclear Proteins; D053764:Presenilin-1; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D014162:Transfection
D016564:Amyloid beta-Protein Precursor; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins; C497762:Notch1 protein, mouse; D009687:Nuclear Proteins; D053764:Presenilin-1; C497571:Rbpj protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D008156:Luciferases; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse