Analysis of remnant reticulocyte mRNA reveals new genes and antisense transcripts expressed in the human erythroid lineage.

BACKGROUND AND OBJECTIVES: We studied the gene expression profile of human purified reticulocytes to provide a transcriptional basis for the study of erythroid biology, differentiation and hematologic disorders. DESIGN AND METHODS: We screened highly purified blood reticulocytes from ten healthy adult volunteers. We chose a modified protocol of serial analysis of gene expression (SAGE), the serial analysis of downsized extracts (SADE).
RESULTS: Data analysis revealed that 64% of gene signatures (tags) matched with known genes; mainly hemoglobin. In addition to the abundant globin mRNA, SAGE analysis identified previously described genes and new transcripts. In reticulocytes, which are poor in mRNA, we also identified 9% of EST and 27% of tags that did not match with any known genes. Mining our data, 70% of the unknown tags and 39% of tags identifying EST were found to be specific to the reticulocyte. We demonstrated the presence of a mRNA that matched with the reverse sequence of the hemoglobin b (HBB) transcript. INTERPRETATION AND
CONCLUSIONS: This is the first description of an antisense transcript of the human HBB gene suggesting regulation by way of sense-antisense pairing. The well-characterized genes found in the SAGE library were genes specific to the blood cell lineage, housekeeping genes and, interestingly, genes not previously described in the reticulocyte. Furthermore the study provides markers of the erythroid lineage regulated during the differentiation process as observed in in vitro experiments.