Fig. 1.

Tax is associated with centrosomes and induces abnormal centrosome morphology and number. Tax associates with centrosome during mitosis. (A) Asynchronous MEFs were transiently transfected with GFP–Tax and fixed with methanol. Signals from GFP–Tax (Alexa Fluor 488), γ-tubulin (Alexa Fluor 568), and DNA (Hoechst 33342) were merged. (B and C) Three hours after transfection, cells were synchronized for 24 h with 2 mM hydroxyurea (B) or 0.2 mg/ml nocodazole (C) and fixed with methanol. GFP–Tax and pericentrin were revealed with Alexa Fluor 488- and 568-conjugated secondary antibodies, respectively. Signals were then merged and are shown. The histograms show a parallel set of cells that were fixed in 70% ethanol and stained with propidium iodide for FACS. (D and E) Tax induces abnormal centrosome amplification. MEFs were transiently transfected with HTLV-1 Tax C-terminally fused to GFP (GFP–Tax). (E) Several enlarged examples of fragmentation of Tax-associated centrosomes. GFP–Tax and pericentrin were revealed with Alexa Fluor 488- and 568-conjugated secondary antibodies, respectively. DNA was counterstained with Hoechst 33342. (F) Centrosomal aberration was many fold higher in Tax-expressing cells than in control cells (300 cells were counted). Arrows point to centrosomes.