Expression of notch receptors, notch ligands, and fringe genes in hematopoiesis

Objective. Hematopoiesis is the process by which mature blood cell types ar e generated from a small population of pluripotent hematopoietic stem cells , How these cells undergo fate selection, however, is not fully understood, The Notch signaling system is known to mediate cell fate decisions of mult ipotent precursors in a wide range of complex animals throughout developmen t, As Notch signaling involves cell-cell interactions, we sought to determi ne the expression of Notch receptors, ligands, and regulators in individual cell populations along the hematopoietic differentiation pathway. Materials and Methods, Described here is a single cell RT-PCR analysis of N otch1, Notch3, Notch4, Notch ligands (Dll1 and Jagged1), and Fringe gene ex pression in cells of the blood system. As previously described, single cell globally amplified cDNA was generated by RT-PCR from various hematopoietic precursor cells whose potential was known from sibling analysis. A precurs or hierarchy slot blot was created containing these cDNAs as well as sample s from maturing blood cell populations and two fibroblast cell lines. The p recursor slot blot was screened with probes for each of the candidate genes . Results. Macrophage precursors expressed high levels of Notch1 transcript, while maturing macrophages expressed high levels of both Notch1 and Notch4, The Jagged 1 ligand transcript was highly expressed in terminally maturing cells including mast cells and megakaryocytes, In contrast, the Manic Frin ge gene was highly expressed in uncommitted bi- and tri-potential precursor s as well as in committed neutrophil and macrophage precursors. Conclusions. Distinct expression patterns of Jagged1 and Manic Fringe sugge st that their corresponding proteins could regulate cell fate choices durin g hematopoiesis and may be responsible for regulating communication between lineage compartments during hematopoietic development. (C) 2000 Internatio nal Society for Experimental Hematology, Published by Elsevier Science Inc.