Accumulation of pathological tau proteins is a significant hallmark of Alzheimer’s disease. detect the manifestation from the recombinant MM-102 gene and endogenous murine ((woodchuck hepatitis pathogen post-transcriptional regulatory component) series for AAV-derived genes as well as the 3′-UTR series of to reduce cross-reactivity. We recognized mRNA signal in every neurons in the MEC or DG (Fig. 1b c) and mRNA sign in the GFP+ cells in the MEC (Fig. 1b) however not in the GCL (Fig. 1c). Notably HT7+ indicators had been recognized in the GCL by 7 dpi with AAV-GFP/tau mice and improved by 28 dpi (Fig. 1d) displaying hTau transmission through the OML towards the GCL. The transmission is confirmed by these data of hTau however not AAV from MEC neurons to GCL neurons. Shape 1 CYFIP1 Tau propagates towards the DG following the shot of AAV-GFP/tau in the MEC from the mouse mind. (a) C57BL/6 mice at 4 weeks of age had been injected in the MEC with AAV-GFP or AAV-GFP/tau after that sacrificed at 7 or 28 dpi and put through immunofluorescence for … Next we examined tau pathology development by immunofluorescence to T22 (a tau oligomer-specific marker) CP13 (specific to pSer202 pTau) HT7 doublecortin (DCX; an immature neuronal cell marker) NeuN (a mature neuronal marker) P2ry12 (a microglia-specific marker) Iba1 (a mononuclear phagocyte marker) GFAP (an astrocytic marker) and activated caspase-3 (an apoptotic cell marker). We detected T22+ cells in the GCL and some of them colocalized with DCX+ in AAV-GFP/tau mice at both 7 and 28 dpi (Figs. 1e and ?and2a).2a). Co-immunostaining with tau markers and several cellular markers revealed that T22+ cells were 56% NeuN+ mature neurons 35 DCX+ immature neurons and 0.8% GFAP+ astrocytes at 7 dpi and 38% DCX+ immature neurons at 28 dpi (Fig. 2b-g). There was no T22 staining in AAV-GFP mice at either 7 or 28 dpi. CP13+ cells were 81% DCX+ immature neurons MM-102 at 7 dpi which MM-102 was reduced to 29% at 28 dpi (Fig. 2e-g) suggesting the maturation of tau-bearing neurons from CP13+DCX+ to MM-102 AT8+NeuN+ cells. Notably 11 of HT7+ cells colocalized with P2ry12+ microglia (Fig. 2e-g) at 7 dpi showing the phagocytosis of hTau by microglia. At 28 dpi AT8+ cells were 66% NeuN+ mature neurons 34 DCX+ immature neurons 18 P2RY12+ microglia and MM-102 5% GFAP+ astrocytes. Microglia showed accumulation around AT8+mTau+ cells in the DG (Fig. MM-102 2c d). HT7+ cells were 34% and 43% DCX+ immature neurons at 7 and 28 dpi respectively. No cells were stained by MC1 (detecting an immature tau aggregation form preceding oligomerization) or thioflavin-S (filamentous tau) in the GCL at either time point. Moreover 80 of the AT8+ cells in the GCL were positive for activated caspase-3 in AAV-GFP/tau mice at 28 dpi (Fig. 2g and Supplementary Fig. 2a) exhibiting cytopathic changes in tau-bearing neurons in the DG. The number of Iba1+ microglia was unchanged between AAV-GFP and AAV-GFP/tau mice in the DG at 7 and 28 dpi (Supplementary Fig. 3a b). These data corroborate with previously reported studies that microglia phagocytose apoptotic tau-bearing neurons15 16 18 21 22 Figure 2 Immunofluorescence for tau with cellular markers. (a) Stacked sequential confocal microscopy imaging at 7 dpi of the GCL in the C57BL/6 mouse brain injected with AAV-GFP/tau into the MEC. DCX green; T22 red; DAPI blue. Scale bar 20 μm. (b c … Depletion of microglia suppresses tau propagation To determine whether microglia actually phagocytose tau aggregates we performed confocal and electron microscopic imaging of PS19 mice expressing P301S human tau (isoform 1N4R containing four microtubule-binding repeats and lacking exon 3). PS19 mice develop tau aggregation by 3 months of age neuroinflammation by 4 months and hippocampal neurodegeneration by 12 months23. Confocal microscopy imaging revealed colocalization of AT8+ pTau with Iba1+ microglia in the hippocampal region (Fig. 3a and Supplementary Fig. 4a). Consistent with this observation double-immunogold labeling and electron microscopy identified PHF1 (pTau at pSer396 and Ser404)-immunoreactive electron-dense materials within Iba1+ microglial processes (Fig. 3a and Supplementary Fig. 4b). Some microglia engulfing tau aggregates were closely.