The pattern of gene expression in human myeloid progenitor cells

We performed a genome-wide analysis of gene expression in primary human myeloid progenitor CD 15 + cells. Over 27,000 unique tag sequences with quantitative information have been identified from ~ 67,000 tags by applying SAGE technique in this study. Of these unique tag sequences, 59 (1.6 %) were expressed at over 100 copies, 6181 and 20860 were expressed at 2-99 and 1 copy, respectively. 46% of the 27,000 tags had no match in the genome database and could be novel genes. Among the 59 highly expressed genes, 15 were mitochondrial genes, 19 were ribosomal proteins (ribo), 20 were genes with various functions, and 5 had multiple matches. Among the 20 other genes, 4 are highly expressed ubiquitously, including eukaryotic translational elongation factor 1, ferritin heavy chain and light chain, and translational-controlled tumor protein. The others have various functions in myeloid differentiation, e.g. heat shock 90KD protein 1, MHC class I, class II , karyopherin alpha 4. Comparing the highly expressed genes identified by SAGE in myeloid progenitor cells with mature monocytes ( Blood.94:845-52 1999 ), three patterns appear: 1 ). Genes highly expressed in myeloid progenitor cells but decreased in monocytes. e.g. cytochrome c oxidase subunit H, S100 calcium-binding protein A8, beta-2-microglobulin, and ferritin heavy polypeptide; 2). Genes expressed lower in myeloid but higher in monocytes. e.g. ferritin light polypeptide, CD74, ribo L4land S27; and 3). Genes expressed at similar level between these two types of cells, e.g. ribo S2 and thymosin beta 4. The difference in gene expression level suggests that they may play important roles in cellular differentiation from myelomonocytic stem cells to myeloid cells and monocytic cells. This study provides unique information about genome-wide gene expression in human myeloid progenitor cells. It also provides a baseline for comparison of alterations in gene expression in myeloid diseases, both malignant and non-malignant.