Figure 7: Tau phosphorylation correlates with cellular uptake. | Nature Communications

Figure 7: Tau phosphorylation correlates with cellular uptake.

From: Neuronal uptake and propagation of a rare phosphorylated high-molecular-weight tau derived from Alzheimer’s disease brain

Figure 7

(a–c) Non-phosphorylated HMW tau was not taken up by neurons. (a) Tau oligomer mixture solution was prepared from recombinant human tau, followed by SEC and tau ELISA. (b) Phospho-tau levels in SEC fractions and brain extracts (pS396 tau ELISA). (c) Each SEC fraction was incubated with primary neurons. Neurons were immunostained at day 2. (d–f) Dephosphorylation reduced tau uptake. (d) Immunoblot analysis of total (Tau13)- and phospho-tau (pS396) levels in rTg4510 (12-month-old) brain extracts treated with lambda phosphatase. (e) SDD-AGE analysis of brain extracts treated with phosphatase. (f) Tau uptake assay. Phosphatase-treated brain extract was applied to HEK-tau-biosensor cells. (n=3, **P<0.01), unpaired t-test. (g–j) Immunodepletion of phospho-tau reduced neuronal tau uptake. rTg4510 (12-month-old) brain extracts were immunodepleted with total- or phospho-tau specific antibodies. (n=5). (g) Total tau levels in tau-immunodepleted samples (ELISA). **P<0.01 versus control IgG. (h) Tau uptake in primary neurons (day 2). *P<0.05 versus control IgG. (i) Blocking efficiency was defined as the percentage of tau-uptake reduction (versus control IgG) multiplied by tau levels in the immunodepleted brain extracts (% control IgG). *P<0.05 versus total tau (HT7). One-way ANOVA and a subsequent Tukey-Kramer test. (j) Representative images of tau uptake in primary neurons. Scale bar, 50 μm.

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