hIAN1 and tal-1 mRNA expression in T-ALL.

(A) The hIAN1 and tal-1 mRNAs levels are reciprocally correlated. Northern blot analysis of hIAN1 and TAL-1 mRNA expression was performed on DU528 and Molt-4 (lanes 1 and 2), 2 T-ALL–derived cell lines that expressed TAL-1 after chromosomal rearrangement (DU528) or by a presently unknown mechanism (Molt-4); and on CEM and RPMI 8402 (lanes 5 and 6), and on 2 T-ALL–derived cell lines that harbor the sil-tal rearrangement. Jurkat and Jurkat-ΔCOOH cell lines (lanes 3 and 4) were used as controls. (B) Forced expression of TAL-1 in Jurkat-ΔCOOH does not modulate hIAN1 gene expression. Jurkat-ΔCOOH cells were transfected with a tal-1 expression vector, and 5 subclones (numbered 1 to 5) that expressed various levels of TAL-1 were selected. Total RNAs from Jurkat, Jurkat-ΔCOOH, and the 5 subclones were extracted, and hIAN1 mRNA level was studied by semiquantitative RT-PCR. The amount of cDNA used for PCR was normalized relative to the levels of the S14 gene product.