Contribution of NOTCH1 dimers to gene expression in established Notch1-induced human T-cell leukemias

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy characterized by an expansion of T-cell progenitors and DNA mutations that lead to an overactive NOTCH1 signaling in over 50% of T-ALL cases. Even though intracellular Notch1(ICN1) can modulate the target gene expression as a monomer, homodimerization of ICN1 is indispensable for the leukemogenesis of mouse T-cells. To define the gene expression profiling modulated by Notch1 dimers in established human T-cell leukemia, NOTCH1-dE-induced leukemia cells, derived from cord blood, were transduced with lentivectors encoding wild type (wt) intracellular Notch1 domain (ICN1), ICN1-R1984A dimer mutant or empty vector as control. Subsequently, transduced cells were FACS-sorted, seeded in wells coated with lymphoid differentiation material and T-cell expansion media (Stemcell Technologies) and treated with gamma-secretase inhibitor (GSI) for four days to inhibit the signal induced by NOTCH1-dE receptor that still requires a gamma-secretase cleavage to generate ICN1.