AGE

, Volume 35, Issue 1, pp 83–101

Insulin receptor signaling mediates APP processing and β-amyloid accumulation without altering survival in a transgenic mouse model of Alzheimer’s disease

  • Oliver Stöhr
  • Katharina Schilbach
  • Lorna Moll
  • Moritz M. Hettich
  • Susanna Freude
  • F. Thomas Wunderlich
  • Marianne Ernst
  • Johanna Zemva
  • Jens C. Brüning
  • Wilhelm Krone
  • Michael Udelhoven
  • Markus Schubert
Article

DOI: 10.1007/s11357-011-9333-2

Cite this article as:
Stöhr, O., Schilbach, K., Moll, L. et al. AGE (2013) 35: 83. doi:10.1007/s11357-011-9333-2

Abstract

In brains from patients with Alzheimer’s disease (AD), expression of insulin receptor (IR), insulin-like growth factor-1 receptor (IGF-1R), and insulin receptor substrate proteins is downregulated. A key step in the pathogenesis of AD is the accumulation of amyloid precursor protein (APP) cleavage products, β-amyloid (Aβ)1-42 and Aβ1–40. Recently, we and others have shown that central IGF-1 resistance reduces Aβ accumulation as well as Aβ toxicity and promotes survival. To define the role of IR in this context, we crossed neuron-specific IR knockout mice (nIR−/−) with Tg2576 mice, a well-established mouse model of an AD-like pathology. Here, we show that neuronal IR deficiency in Tg2576 (nIR−/−Tg2576) mice leads to markedly decreased Aβ burden but does not rescue premature mortality of Tg2576 mice. Analyzing APP C-terminal fragments (CTF) revealed decreased α-/β-CTFs in the brains of nIR−/−Tg2576 mice suggesting decreased APP processing. Cell based experiments showed that inhibition of the PI3-kinase pathway suppresses endosomal APP cleavage and decreases α- as well as β-secretase activity. Deletion of only one copy of the neuronal IGF-1R partially rescues the premature mortality of Tg2576 mice without altering total amyloid load. Analysis of Tg2576 mice expressing either a dominant negative or constitutively active form of forkhead box-O (FoxO)1 did not reveal any alteration of amyloid burden, APP processing and did not rescue premature mortality in these mice. Thus, our findings identified IR signaling as a potent regulator of Aβ accumulation in vivo. But exclusively decreased IGF-1R expression reduces AD-associated mortality independent of β-amyloid accumulation and FoxO1-mediated transcription.

Keywords

Insulin receptorInsulin-like growth factor-1 receptorβ-AmyloidAlzheimer’s diseaseTg2576 mice

Supplementary material

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Supplementary Fig. 1

a Mutant FoxO1 constructs. b Cloning strategy of FoxO1DN and FoxO1ADA mice, IRES-internal ribosomal entry site, and WSS westphal stop sequence. c Immunohistochemistry using antibodies against eGFP in Rosa FoxO1DN Syn-Cre mice and respective controls (JPEG 88 kb)

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Supplementary Fig. 2

Insulin-stimulated Akt and Erk-1/-2 phosphorylation is decreased in hippocampi from nIR−/− mice. Isolated hippocampi of WT and nIR−/− mice were stimulated with insulin (5 nM) for 10 min. Hippocampal lysates were subject to SDS-PAGE and Western blotting. Membranes were probed using antbodies against pAktser473, Akt, pErk-1/-2Thr202/Tyr204, and Erk-1/-2 (JPEG 13 kb)

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Supplementary Fig. 3

Characterization of nIR−/−Tg2576 mice and respective controls up to the age of 60 weeks. a Body weight from male and female animals. b Blood glucose levels from male and female animals. Data were assessed from 66 female (50 Tg2576 and 16 nIR−/−Tg2576) and 66 male mice (52 Tg2576 and 14 nIR−/−Tg2576) (JPEG 44 kb)

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Supplementary Fig. 4

Reduced IGF-1R expression and decreased IGF-1-stimulated Akt phosphorylation in isolated hippocampi from nIGF-R+/− mice. a Determination of the abundance of IGF-1Rs from hippocampal lysates of WT and nIGF-R+/− mice using Western blots. b Isolated hippocampi of WT and nIGF-R+/− mice were stimulated with IGF-1 (5 nM) for 10 min. Hippocampal lysates were subject to SDS-PAGE and Western blotting. Membranes were probed using antibodies against pAktser473 and Akt (JPEG 15 kb)

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Supplementary Fig. 5

Characterization of nIGF-R+/−Tg2576 mice and respective controls up to the age of 60 weeks. a Body weight from male and female animals. b Blood glucose levels from male and female animals. Data were assessed from 50 female (40 Tg2576 and 10 nIR−/−Tg2576) and 49 male mice (31 Tg2576 and 18 nIR−/−Tg2576) (JPEG 41 kb)

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Supplementary Fig. 6

Characterization of FoxO1ADATg2576 mice and respective controls up to the age of 60 weeks. a Body weight from male and female animals. b Blood glucose levels from male and female animals. Data were assessed from 50 female (37 Tg2576 and 13 FoxO1ADATg2576) and 39 male mice (37 Tg2576 and 2 FoxO1ADATg2576). c Western blots of hippocampal lysates for the IGF-1R, pAktser473, Akt, pErk-1/-2Thr202/Tyr204, and Erk-1/-2 from female WT, FoxO1ADATg2576, FoxO1ADA, and Tg2576 mice (n = 4 per genotype) (JPEG 36 kb)

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Supplementary Fig. 7

Characterization of FoxO1DNTg2576 mice and respective controls up to the age of 60 weeks. a Body weight from male and female animals. b Blood glucose levels from male and female animals. Data were assessed from 70 female (56 Tg2576 and 14 FoxO1DNTg2576) and 56 male mice (44 Tg2576 and 12 FoxO1DNTg2576). c Western blot analysis for IGF-1R, IR, pAktser473, Akt, pErk-1/-2Thr202/Tyr204, Erk-1/-2, and FoxO1 from hippocampal lysates of WT, FoxO1DNTg2576, FoxO1DN, and Tg2576 mice (n = 4 per genotype) (JPEG 38 kb)

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Copyright information

© American Aging Association 2011

Authors and Affiliations

  • Oliver Stöhr
    • 1
  • Katharina Schilbach
    • 1
  • Lorna Moll
    • 1
  • Moritz M. Hettich
    • 1
    • 4
  • Susanna Freude
    • 1
    • 2
  • F. Thomas Wunderlich
    • 2
    • 3
  • Marianne Ernst
    • 2
    • 5
  • Johanna Zemva
    • 1
  • Jens C. Brüning
    • 1
    • 2
    • 3
    • 5
  • Wilhelm Krone
    • 1
    • 2
  • Michael Udelhoven
    • 1
    • 2
    • 6
  • Markus Schubert
    • 1
    • 2
    • 6
  1. 1.Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), Center for Molecular Medicine Cologne (CMMC)University of CologneCologneGermany
  2. 2.Cologne excellence cluster in Cellular Stress Responses in Aging-Associated Diseases (CECAD)University of CologneCologneGermany
  3. 3.Max Planck Institute for Neurological ResearchCologneGermany
  4. 4.Molecular and Cellular Cognition LabGerman Centre for Neurodegenerative Diseases (DZNE)BonnGermany
  5. 5.Department of Mouse Genetics and MetabolismInstitute for Genetics University of CologneCologneGermany
  6. 6.Center for Endocrinology, Diabetes and Preventive MedicineUniversity of CologneCologneGermany