LIM domain-binding protein 1 (LDB1) binds to the LIM domain of LIM homeodomain proteins which are transcriptional regulators. LDB1 is a multi-adaptor protein that mediates interactions between different classes of transcription factors and their co-regulators, and hence determine cell fate and differentiation []. In erythroid cells LDB1 is recruited to the beta-globin locus via LMO2 and is required for looping of the beta-globin locus control region (LCR) to the active beta-globin promoter [].
Hepatic leukemia factor (HLF) belongs to the PAR (Proline and Acidic amino acid-Rich basic leucine ZIPper) transcription factor family, which consists of HLF, DBP and TEF proteins []. HLF binds DNA specifically as a homodimer or as a heterodimer with other PAR factors. It binds to the consensus sequence 5'-GTTACGTAAT-3' []. In B-precursor acute lymphoblastic leukemia (ALL), it fuses to the N terminus of the E2A protein [], and this chimeric protein promotes cell survival of t(17;19)-ALL cells by aberrantly up-regulating the expression of hematopoiesis transcription regulator LMO2 []. HLF regulates a complex multi-gene transcriptional program that involves upregulation of anti-apoptotic genes and downregulation of pro-apoptotic genes [].
