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. 2009 Nov 19;4(11):e7917.
doi: 10.1371/journal.pone.0007917.

Experimental diabetes mellitus exacerbates tau pathology in a transgenic mouse model of Alzheimer's disease

Yazi D Ke  1 , Fabien Delerue, Amadeus Gladbach, Jürgen Götz, Lars M Ittner
Affiliations

Experimental diabetes mellitus exacerbates tau pathology in a transgenic mouse model of Alzheimer's disease

Yazi D Ke et al. PLoS One. .

Abstract

Diabetes mellitus (DM) is characterized by hyperglycemia caused by a lack of insulin, insulin resistance, or both. There is increasing evidence that insulin also plays a role in Alzheimer's disease (AD) as it is involved in the metabolism of beta-amyloid (Abeta) and tau, two proteins that form Abeta plaques and neurofibrillary tangles (NFTs), respectively, the hallmark lesions in AD. Here, we examined the effects of experimental DM on a pre-existing tau pathology in the pR5 transgenic mouse strain that is characterized by NFTs. pR5 mice express P301L mutant human tau that is associated with dementia. Experimental DM was induced by administration of streptozotocin (STZ), which causes insulin deficiency. We determined phosphorylation of tau, using immunohistochemistry and Western blotting. Solubility of tau was determined upon extraction with sarkosyl and formic acid, and Gallyas silver staining was employed to reveal NFTs. Insulin depletion by STZ administration in six months-old non-transgenic mice causes increased tau phosphorylation, without its deposition or NFT formation. In contrast, in pR5 mice this results in massive deposition of hyperphosphorylated, insoluble tau. Furthermore, they develop a pronounced tau-histopathology, including NFTs at this early age, while the pathology in sham-treated pR5 mice is moderate. Whereas experimental DM did not result in deposition of hyperphosphorylated tau in non-transgenic mice, a predisposition to develop a tau pathology in young pR5 mice was both sufficient and necessary to exacerbate tau deposition and NFT formation. Hence, DM can accelerate onset and increase severity of disease in individuals with a predisposition to developing tau pathology.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Effects of streptozotocin (STZ) administration in mice.
(A) STZ injection in both 4 months old wild-type (WT) and pR5 mice induces chronically high blood glucose levels, while levels in sham-injected WT and pR5 control mice are normal (n = 12). Blood glucose levels remained high until mice were analyzed at 6 months of age. (B) Hematoxylin/eosin staining and (C) immunofluorescence staining with insulin- (green) and glucagon-specific (red) antibodies of pancreatic islets of Langerhans reveals comparable islet architecture in 6 months old sham-injected WT and pR5 mice. However, insulin producing β-cells are absent from both WT and pR5 islets 60 days after STZ administration, whereas glucagon secreting α-cells remained. Nuclei were counterstained with DAPI (blue). Scale bar, 25 µm.
Figure 2
Figure 2. Increased tau phosphorylation in STZ-treated pR5 mice.
Immunohistochemistry with phosphorylation site-specific antibodies reveals several AT8-positive neurons in the amygdala of sham-injected pR5 mice at 6 months of age. Whereas in sham-injected pR5 mice most AT8-positive cells lack PS422 staining (open arrowhead), there is a subset of neurons that also stains with PS422 (arrowhead). Similarly, dystrophic neurites were AT8- but not PS422-positive in sham-injected pR5 mice (inset). In contrast, upon STZ injection virtually all tau-containing neurons (arrowhead), and dystrophic neurites (inset) within the amygdala of pR5 mice stained with both AT8 and PS422, as revealed by overlay (yellow). Quantification of AT8 and PS422 double positive cells confirms significantly increased numbers of AT8/PS422 double positive in the amygdala of STZ-treated compared to sham-injected pR5 mice (**, P<0.001; n = 6). Scale bar, 50 µm.
Figure 3
Figure 3. Increased numbers of NFTs in STZ-treated pR5 mice.
Gallyas silver staining (black) of coronal section revealed abundant numbers of flame-shaped NFTs and dystrophic neurites in the amygdala of STZ-treated pR5 mice. In sham-injected pR5 mice, NFTs were rare. No NFTs are found in sham- and STZ-injected wild-type (WT) mice. Quantification of standardized serial sections showed 8-fold increased numbers of NFTs in pR5 mice upon STZ-treatment (**, P<0.001, n = 6). Scale bar, 50 µm.
Figure 4
Figure 4. STZ administration does not affect transgene expression levels and pattern.
(A) Immunohistochemistry using the human tau specific antibody HT7 reveals a similar expression pattern in the amygdala of STZ-treated or sham-injected pR5 mice (n = 6). Scale bar, 50 µm. (B) Western blotting of protein extracts from amygdala of STZ-treated or sham-injected pR5 mice (n = 6) shows comparable levels of transgenic human (triangle) and endogenous murine (asterisk) tau, as detected by TAU5. GAPDH confirms equal loading and was used to normalize TAU5 band intensities for quantification.
Figure 5
Figure 5. STZ-treatment induces hyperphosphorylation of tau in pR5 and non-transgenic mice, but only in pR5 mice it induced tau insolubility.
(A) Amygdalae of STZ- or sham-injected wild-type (WT) and pR5 mice were extracted with buffers of increasing stringency and separated by SDS-PAGE for Western blotting. RAB fractions contain soluble species of both transgenic human (triangle) and endogenous murine (asterisk) tau, as shown with HT7 and TAU5, respectively. Phosphorylation site-specific tau antibodies AT8, AT270, AT100, 12E8, PHF-1 and PS422 (for details on antibodies see Table 1) reveal increased phosphorylation of transgenic and endogenous tau at multiple sites upon STZ-treatment. In sham-treated controls, tau is slightly more phosphorylated in pR5 than WT mice. GAPDH confirmed equal loading. (B) RIPA fractions of STZ-treated mice contain higher amounts of both transgenic and endogenous tau than in sham-treated controls. Actin confirmed equal loading. (C) Insoluble proteins were extracted with formic acid (FA). In STZ-treated mice, HT7 and TAU5 show insoluble transgenic and endogenous tau, whereas no tau is detectable in STZ-treated non-transgenic (WT) or sham-injected non-transgenic and pR5 mice. (D) Extraction of sarkosyl-insoluble tau from amygdala reveals significant amounts of sarkosyl-insoluble transgenic human tau (HT7) were isolated from STZ-treated, but not sham-injected pR5 mice.
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References

    1. Gotz J, Streffer JR, David D, Schild A, Hoerndli F, et al. Transgenic animal models of Alzheimer's disease and related disorders: histopathology, behavior and therapy. Mol Psychiatry. 2004;9:664–683. - PubMed
    1. Ballatore C, Lee VM, Trojanowski JQ. Tau-mediated neurodegeneration in Alzheimer's disease and related disorders. Nat Rev Neurosci. 2007;8:663–672. - PubMed
    1. Lee VM, Goedert M, Trojanowski JQ. Neurodegenerative tauopathies. Annu Rev Neurosci. 2001;24:1121–1159. - PubMed
    1. Cairns NJ, Bigio EH, Mackenzie IR, Neumann M, Lee VM, et al. Neuropathologic diagnostic and nosologic criteria for frontotemporal lobar degeneration: consensus of the Consortium for Frontotemporal Lobar Degeneration. Acta Neuropathol. 2007;114:5–22. - PMC - PubMed
    1. Selkoe DJ. Alzheimer's disease: genotypes, phenotypes, and treatments. Science. 1997;275:630–631. - PubMed

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