Fig. 1. The Aiolos gene codes multiple isoforms. (A) A representative RT-PCR with primers corresponding to exon 1 and 7 in hematopoietic cell lines derived from human B leukemic (697, RAMOS, RS11;846, REH) and T leukemic (JURKAT, SUPT11) cells and the NKL cell line, derived from natural killer (NK) cells. (B) Schematic representation of Aiolos isoforms. Green boxes in exons 3-5 indicate the four N-terminal zinc finger motifs involved in DNA binding and the two violet boxes in exon 7 indicate the C-terminal motifs required for dimer formation. The two Aiolos isoforms (at the bottom) contain an alternative exon, which we have named exon 5a (see Results). Aiolos isoforms have been named according to the exons missing from the full-length isoform. Ikaros full-length isoform Ik-1 is also shown at the bottom. Nine novel Aiolos isoforms are indicated on the right by asterisks. (C) RT-PCR analysis of non-hematopoietic human cell lines (monkey SV40-transformed fibroblast cell line COS-7, breast cell line MCF 7, liver cell line HEPG2, a neuroblastoma-derived cell line SHSY-5Y and kidney cell line HEK) also show the presence of multiple Aiolos isoforms. Molecular weight (MW) markers are included. PCR products were transferred onto a nylon membrane and hybridized with a specific C-terminal Aiolos probe in order to confirm the identity of the PCR bands (bottom panel). (D) Representative RT-PCR analysis of B cells including B-cell-derived lymphoblastoid cells (B-PBL), and samples from healthy subjects (N1-N4) and individuals with systemic lupus erythematosus (SLE1-SLE4) and rheumatoid arthritis (RA1-RA4).