BCL11B inactivation in human T-ALL. (A) Array CGH was performed on genomic DNA from diagnostic lymphoblast specimens collected from 47 children with T-ALL. The CGH data are shown as a dChip plot of segmented log2 copy number ratios. Heterozygous deletions involving BCL11B were identified in 6% (n = 3 of 47) primary T-ALL specimens. (B) Sequencing of BCL11B coding sequence was performed in 43 of these cases together with an additional cohort of 70 T-ALL specimens, revealing heterozygous missense BCL11B mutations in 7 primary patient samples, as well as in 19% (n = 3 of 16) of T-ALL cell lines. Taken together, we thus identified monoallelic BCL11B lesions in 9% (n = 10 of 117) of primary T-ALL patient samples. Mutations are shown based on the full-length CCDS9950.1 BCL11B isoform. (C-E) Homology structural modeling of canonical DNA binding by the BCL11B ZF2-ZF3 zinc fingers was performed based on the high-resolution crystal structure of Zif268 in complex with DNA oligonucleotide.20 (C) His445 and His479 are required for coordination of the structural zinc ions of the ZF2 and ZF3 domains, respectively, and their mutations to Tyr are predicted to unfold of the BCL11B zinc fingers. (D-E) Arg447 and Arg472 form salt bridge and hydrogen bonds with the phosphate backbone and nucleotide bases of DNA, respectively, and their mutations to His are predicted to disrupt DNA binding. Yellow dotted lines depict salt bridge and hydrogen bonds.
