SCL/TAL1 (stem cell leukemia/T-cell acute lymphoblastic leukemia [T-ALL] 1) is an essential transcription factor in normal and malignant hematopoiesis.
We previously showed that mouse fetal liver (FL) hemato/vascular cells from day 12 of gestation (E12), expressing the Stem Cell Leukaemia (SCL) gene enhancer transgene (SCL-PLAP<sup>+</sup> cells), had robust endothelial engraftment potential when transferred to the blood stream of newborns or adult conditioned recipients, compared to the scarce vascular contribution of adult bone marrow cells.
Actually, in patients, SCL transcription initiated at promoter 1b is restricted to primitive CD34+CD41- progenitor cells, while it is detectable in both cell subsets from healthy subjects; (iii) the full-length isoform of SCL protein is present in patients' CD34+ cells and in PBMC; in the latter the SCL-expressing cells mainly belong to the MK lineage in which its sublocalization is both nuclear and cytoplasmic, which contrasts with the sole nuclear staining observed in normal MK cells.
The interstitial deletion at 1p32 involving SIL (SCL-interrupting locus)/SCL (stem cell leukemia) is a case involving two non-V(D)J sites that have been suggested to be V(D)J recombination mistakes.
The SCL gene, initially discovered at the site of a translocation breakpoint associated with the development of a stem cell leukemia, encodes a protein that contains the highly conserved basic helix-loop-helix (bHLH) motif found in a large array of eukaryotic transcription factors.
This translocation may identify a gene for which we propose the name SCL (stem-cell leukemia) that is important for hemopoietic development and oncogenesis and that has been disrupted or altered in this stem-cell line.
We have identified the human gene, SCL.We discovered this gene because of its involvement in a chromosomal translocation associated with the occurrence of a stem cell leukemia manifesting myeloid and lymphoid differentiation capabilities.