Overexpression of TIS11b.

Overexpression of TIS11b induced G-CSF–dependent proliferation of L-G cells but did not block their terminal differentiation as completely as AML1-MTG8. (A) G-CSF–dependent growth of control (LNSX and LNCX) and AML1-MTG8- and TIS11b-expressing L-G cells. Three infections were independently performed for each construct. These infected cells were separately cultured in the presence of 10 ng/mL G-CSF instead of IL-3. The averages of these 3 experiments are shown. Error bars indicate standard deviations. (B) Comparison of the expression of TIS11bby Northern blotting analysis in control (LNSX and LNCX) and AML1-MTG8- and TIS11b-expressing L-G cells. The membrane was successively hybridized with mouse TIS11b cDNA and human G3PDH cDNA. The positions of bands representing the endogenous TIS11b and the exogenousTIS11b genes, whose expression was directed by the LTR (upper) and the CMV promoter (lower) of the LNCX vector, are indicated on the right. The signal of the lower exogenous TIS11b gene transcript was about 10-fold higher than that of the endogenous TIS11bgene transcript in control cells. (C) Western blotting analysis of the expression of AML1-MTG8 and TIS11b in the infected L-G cells. Each protein was detected with anti-HA antibody. The positions of bands of AML1-MTG8 and TIS11b are indicated on the right. (D) Nuclear morphology of the L-G infectants when cultured in the presence of G-CSF. The cells cultured in the presence of G-CSF were stained with May-Grünwald and Giemsa solutions at the indicated days.