Fig 1.
Normal body weight in aged tauGFP/GFP mice.
(A) Knockin strategy of eGFP into the MAPT locus of tauGFP/GFP mice (adopted from Tucker et al. 2001). (B) Breeding strategy to obtain aged tauGFP/GFP, tau+/GFP and tau+/+ mice. All genotypes were obtained at Mendelian distribution as indicated as % of total mice. (C) Genotyping of MAPT and eGFP in tauGFP/GFP (–/–), tau+/GFP (+/–) and tau+/+ (+/+) mice. (D) Western blotting of tauGFP/GFP, tau+/GFP and tau+/+ brain extracts, showing reduction/loss of tau and expression of GFP in tau+/GFP and tauGFP/GFP mice. (E) No significant differences in body weight between tauGFP/GFP, tau+/GFP and tau+/+ mice or both genders at 16 months of age.
Fig 2.
Normal brain imaging in aged tauGFP/GFP mice.
(A) Representative coronal MRI scan showing no morphological changes in 19–20 month-old tauGFP/GFP (–/–) and tau+/GFP (+/–) compared to tau+/+ (+/+) mice. (B) Whole organ rendering of MRI brain scans from tauGFP/GFP, tau+/GFP and tau+/+ mice, revealed unchanged brain volumes in tauGFP/GFP and tau+/GFP compared to tau+/+ mice (n = 3/genotype/gender). (C) Representative R2* relaxation images of tauGFP/GFP, tau+/GFP and tau+/+ MRI scans. White boxes demark area used for determining R2* relaxation extinction co-efficient in amygdala, hippocampus and cortex (see D). (D) Comparable R2* relaxation curves for amygdala (AMY), hippocampus (HIP) and cortex (CTX) in tauGFP/GFP, tau+/GFP and tau+/+ mice. (E) R2* relaxation rates were indistinguishable in AMY, HIP and CTX of tauGFP/GFP, tau+/GFP and tau+/+ mice (n = 6).
Fig 3.
Absence of motor, memory and behavioral deficits in aged tauGFP/GFP mice.
Eight male and 12 female tauGFP/GFP (–/–), 18 male and 20 female tauGFP/+ (+/–), and 12 male and 15 female tau+/+ (+/+) mice were tested, unless otherwise stated; (A) Similar latencies to fall on the accelerating Rota-Rod presented by tauGFP/GFP, tau+/GFP and tau+/+ mice of both genders over 3 test days. (B) Comparable latency to fall off the inverted wire suggesting similar grip strength in tauGFP/GFP, tau+/GFP and tau+/+ mice. (C) Examples of swim paths in the Morris water maze from tauGFP/GFP, tau+/GFP and tau+/+ mice (small circle indicates position of submerged escape platform). Similar improvements in the latency to find the submerged platform in female and male tauGFP/GFP, tau+/GFP and tau+/+ mice suggesting normal memory formation (1 female tauGFP/GFP, 2 female tau+/GFP and 4 female tau+/+ mice were excluded due to floating behavior). (D) Both, female and male tauGFP/GFP, tau+/GFP and tau+/+ mice spent comparable times in the target quadrant during probe trials. (E) All mice found the marked platform similarly fast and average swim speed during MWM testing was comparable between genotypes, suggesting normal vision and swimming performance. (F) Examples of exploration paths of tauGFP/GFP, tau+/GFP and tau+/+ mice in the open field arena during the first minute of 10 minute trials. Activity of all mice were comparable, as determined by distance travelled per minute. (G) No differences in time spent in the inner zone during OF testing of tauGFP/GFP, tau+/GFP and tau+/+ mice. (H) During elevated plus maze testing, both female and male tauGFP/GFP, tau+/GFP and tau+/+ mice predominantly spent time in the closed arms, with no differences between genotypes, suggesting no changes in anxiety/disinhibition.
Fig 4.
No loss of substantia nigra neurons and synaptic proteins in aged tauGFP/GFP mice.
(A) Stereological assessment of serial coronal sections of tauGFP/GFP (–/–), tau+/GFP (+/–) and tau+/+ (+/+) brains stained with a tyrosine hydroxylase (TH)-specific antibody revealed indistinguishable numbers of dopaminergic SN neurons (n = 5/genotype). Representative stainings are shown. (B) Western blotting of brain extracts from cortex and hippocampus of 20 month-old tauGFP/GFP, tau+/GFP and tau+/+ mice showed no significant changes in levels of PSD-95, drebrin, NR1 and NR2B, and due to reduction of tau levels (and expression of GFP). Gapdh was probed to confirm equal loading. Quantification of blots was done from independent animals (n = 5; One-way ANOVA: **P<0.01, ***P<0.001, ****P<0.0001; Student’s t-test: *P<0.05 vs WT; ns, not significant (P-values provided)).