Effect of t(11;14)(p13;q11) derivative chromosome configuration on LMO2 expression in T-ALL. (A) Schematic diagram depicting the human TCRD locus that is located within the TCRA locus; V, D, and J gene segments and the TCRD enhancer are indicated. Schematic diagram of LMO2; the 6 exons are indicated (I-VI), of which the coding exons (exon IV partly, exons V and VI) are indicated in black and noncoding exons in white. The distal and proximal promoters are indicated by bent arrows, whereas NRE indicates the negative regulatory element located within the distal promoter. Exact breakpoint location of the t(11;14)(p13;q11) cases of the present study are indicated. The 3 major breakpoint regions with regard to LMO2-coding region and NRE are indicated. Arrowheads under the gene indicate molecular characterized LMO2 breakpoint regions involved in TCR-associated translocations as described in the literature: 1 = t(11,14)(p13;q11),9 ; 2 = t(7,11)(q34;p13)19 ; 3 = t(11,14)(p13;q11)6,7 and t(7;11)(q34;p13)8 ; 4 = t(11,14)(p13;q11)4,8 ; 5 = t(11,14)(p13;q11).4,5 White triangles orientated to the left and black triangles orientated to the right as depicted above the LMO2 locus indicate 12-bp cRSS and 23-bp cRSS, respectively, that were identified with the RIC algorithm and that pass the functionality threshold and are orientated in the appropriate direction for potential involvement in t(11;14)(p13;q11). The 25-kb area indicated 3′ of LMO2 contains another 17 23-bp cRSSs and 1 12-bp cRSS. (B) LMO2 RQ-PCR expression in T-ALL with t(11;14)(p13;q11) with different derivative chromosome configurations, as presented in Table 2. (C) LMO2 RQ-PCR expression in consecutive T-cell developmental stages isolated from 6 pooled human thymus samples (aged 6 wk to 3.5 y; median, 11 mo). LMO2 expression in panels B-C is normalized to the expression level of ABL and given as percentages of LMO2 expression relative to ABL expression. (D) One representative thymus demonstrating PCR/Southern blot analyses of total human thymocytes for t(11;14)(p13;q11) coding joints (CJ) due to either the involvement of cRSSa located just downstream of the LMO2 NRE and frequently involved in T-ALL or the involvement of cRSSb located in LMO2 intron 4. In total, 2 of 4 thymi tested contained t(11;14)(p13;q11), each having 2 of 10 positive PCR reactions for t(11;14)(p13;q11) involving cRSSa, whereas 1 had 2 of 10 and the other 3 of 10 positive PCR reactions for t(11;14)(p13;q11) involving cRSSb.
