IDENTIFICATION OF GENES EXPRESSED IN HUMAN CD34(+) HEMATOPOIETIC STEMPROGENITOR CELLS BY EXPRESSED SEQUENCE TAGS AND EFFICIENT FULL-LENGTHCDNA CLONING/

Hematopoietic stem/progenitor cells (HSPCs) possess the potentials of self-renewal, proliferation, and differentiation toward different line ages of blood cells. These cells not only play a primordial role in he matopoietic development hut also have important clinical application, Characterization of the gene expression profile in CD34(+) HSPCs may l ead to a better understanding of the regulation of normal and patholog ical hematopoiesis, In the present work, genes expressed in human umbi lical cord blood CD34+ cells were catalogued by partially sequencing a large amount of cDNA clones [or expressed sequence tags (ESTs)] and a nalyzing these sequences with the tools of bioinformatics. Among 9,866 ESTs thus obtained, 4,697 (47.6%) showed identity to known genes in t he GenBank database, 2.603 (26,4%) matched to the ESTs previously depo sited in a public domain database, 1,415 (14.3%) were previously undes cribed ESTs, and the remaining 1,151 (11.7%) were mitochondrial DNA, r ibosomal RNA, or repetitive (Alu or L1) sequences. Integration of ESTs of known genes generated a profile including 855 genes that could be divided into different categories according to their functions. Some ( 8.2%) of the genes in this profile were considered related to early he matopoiesis. The possible function of ESTs corresponding to so far unk nown genes were approached by means of homology and functional motif s earches. Moreover, attempts were made to generate libraries enriched f or full-length cDNAs, to better explore the genes in HSPCs, Nearly 60% of the cDNA clones of mRNA under 2 kb in our libraries had 5' ends up stream of the first ATG codon of the ORF, With this satisfactory resul t, we have developed an efficient working system that allowed fast seq uencing of 32 full-length cDNAs, 16 of them being mapped to the chromo somes with radiation hybrid panels. This work may lay a basis for the further research on the molecular network of hematopoietic regulation,