title: Holo-APP and G-protein-mediated signaling are required for sAPPα-induced activation of the Akt survival pathway.
abstract: Accumulating evidence indicates that loss of physiologic amyloid precursor protein (APP) function leads to reduced neuronal plasticity, diminished synaptic signaling and enhanced susceptibility of neurons to cellular stress during brain aging. Here we investigated the neuroprotective function of the soluble APP ectodomain sAPPα (soluble APPα), which is generated by cleavage of APP by α-secretase along the non-amyloidogenic pathway. Recombinant sAPPα protected primary hippocampal neurons and SH-SY5Y neuroblastoma cells from cell death induced by trophic factor deprivation. We show that this protective effect is abrogated in neurons from APP-knockout animals and APP-depleted SH-SY5Y cells, but not in APP-like protein 1- and 2- (APLP1 and APLP2) depleted cells, indicating that expression of membrane-bound holo-APP is required for sAPPα-dependent neuroprotection. Trophic factor deprivation diminished the activity of the Akt survival pathway. Strikingly, both recombinant sAPPα and the APP-E1 domain were able to stimulate Akt activity in wild-type (wt) fibroblasts, SH-SY5Y cells and neurons, but failed to rescue in APP-deficient neurons or fibroblasts. The ADAM10 (a disintegrin and metalloproteinase domain-containing protein 10) inhibitor GI254023X exacerbated neuron death in organotypic (hippocampal) slice cultures of wt mice subjected to trophic factor and glucose deprivation. This cell death-enhancing effect of GI254023X could be completely rescued by applying exogenous sAPPα. Interestingly, sAPPα-dependent Akt induction was unaffected in neurons of APP-ΔCT15 mice that lack the C-terminal YENPTY motif of the APP intracellular region. In contrast, sAPPα-dependent rescue of Akt activation was completely abolished in APP mutant cells lacking the G-protein interaction motif located in the APP C-terminus and by blocking G-protein-dependent signaling with pertussis toxin. Collectively, our data provide new mechanistic insights into the physiologic role of APP in antagonizing neurotoxic stress: they suggest that cell surface APP mediates sAPPα-induced neuroprotection via G-protein-coupled activation of the Akt pathway.
authors.affiliation: Experimental Neurosurgery, Goethe University Hospital, Frankfurt am Main, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Milosch
authors.affiliation: Experimental Neurosurgery, Goethe University Hospital, Frankfurt am Main, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Tanriöver
authors.affiliation: Experimental Neurosurgery, Goethe University Hospital, Frankfurt am Main, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kundu
authors.affiliation: Institute of Cellular and Molecular Anatomy (Anatomie III), Frankfurt University Hospital, Frankfurt am Main, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Rami
authors.affiliation: Inserm and Sorbonne Universities, UPMC, Research Center Saint-Antoine, Paris, France.
authors.forename: J-C
authors.initials: JC
authors.lastname: François
authors.affiliation: Division of Human Biology and Human Genetics, Technical University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Baumkötter
authors.affiliation: Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany.
authors.forename: S W
authors.initials: SW
authors.lastname: Weyer
authors.affiliation: Department of Pharmaceutical Chemistry, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Samanta
authors.affiliation: Department of Pharmaceutical Chemistry, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Jäschke
authors.affiliation: Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, Langen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Brod
authors.affiliation: Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, Langen, Germany.
authors.forename: C J
authors.initials: CJ
authors.lastname: Buchholz
authors.affiliation: Division of Human Biology and Human Genetics, Technical University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kins
authors.affiliation: Institute for Pathobiochemistry, University Medical Center, Mainz University, Mainz, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Behl
authors.affiliation: Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany.
authors.forename: U C
authors.initials: UC
authors.lastname: Müller
authors.affiliation: Experimental Neurosurgery, Goethe University Hospital, Frankfurt am Main, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Kögel
mesh_terms: D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D000072197:ADAM10 Protein; D020816:Amino Acid Motifs; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D037342:Pertussis Toxin / Q000633:toxicity; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D051722:ADAM Proteins; D000072197:ADAM10 Protein; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor; D004151:Dipeptides; D006877:Hydroxamic Acids; D008565:Membrane Proteins; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011994:Recombinant Proteins; C555398:3-(formylhydroxyamino)-2-(3-phenyl-1-propyl)butanoic acid (2,2-dimethyl-1-methylcarbamoyl-1-propyl)amide; C491236:ADAM10 protein, human