Page:Human wild-type full-length tau accumulation disrupts mitochondrial dynamics and the functions via increasing mitofusins.pdf/4

https://www.nature.com/srep/

'''Expression of htau induces mitochondrial accumulation and elongation. (a-e)''' mito-DsRed2 was transfected into S293tau and S293vec cells respectively for 24 h, and then the cellular area devoid of mitochondria (b) (p < 0.0001), the cell population with normal or abnormal mitochondrial distribution (c) (p$normal$ < 0.0001, p$abnormal$ < 0.0001), the mitochondrial length (d) (p < 0.0001), and the cell population with different type of mitochondria (e) (p$normal$ < 0.0001, p$elongated$ < 0.0001, p$fragmented$ = 0.0038) were analyzed. (f–j) HEK293 cells were co-transfected with eGFP-labeled human tau or the vectors and mito-DsRed2 (T293tau or T293vec) for 24 h, and then analyzed as indicated. ((g) p < 0.0001; (h) p$normal$ < 0.0001, p$abnormal$ < 0.0001; (i) p < 0.0001; (j) p$normal$ < 0.0001, p$elongated$ < 0.0001, p$fragmented$ < 0.0001). (k–m) The rat primary hippocampal neurons (7 div) were co-transfected with eGFP-labeled human tau or the vector and mito-DsRed2 for 24 h, and then the mitochondrial length and number (counted in the neuronal processes 100 to 300 μm away from the cell body) were measured. The data were expressed as mean ± SD, at least 100 HEK293 cells or 60 primary neurons were counted in each group. ((l) p < 0.0001; (m) p < 0.0001). ***,p < 0.001 vs vec.

downregulation of OPA1 to ~50% of the control level did not rescue the htau-induced mitochondrial impairment (Fig. S9). Simultaneously, knockdown of Mfn1/2 ameliorated the htau-induced mitochondrial dysfunction with restoration of cell viability at 72 h after tau overexpression (Fig. 5i,j). These data indicate that accumulation of the mitofusins mediates the htau-induced mitochondrial and cellular impairments.

Mitofusin accumulation and mitochondrial dysfunction were detected in the brains of htau transgenic mice Finally, we found that levels of Mfn1, Mfn2, and OPA1 were also significantly increased in hippocampus of 6 month-old htau transgenic mice (STOCK Mapttm1(EGFP)Klt Tg(MAPT)8cPdav/J) compared with the age-matched littermates (Fig. 6a,b), simultaneously, the perinuclear mitochondrial accumulation were also shown by electron microscopy and mitochondrial dysfunctions were found (Fig. 6c–f). Scientific Reports