INDUCTION OF ERYTHROID GENE-EXPRESSION BY MICROCELL FUSION

The molecular events which underlie lineage commitment and differentia tion in hematopoietic cells are still incompletely understood. Microce ll fusion is a versatile technique which has been utilized in characte rizing and mapping genes involved in tumor suppression, cell senescenc e, and certain aspects of differentiation. Microcell fusion has the po tential to contribute to the understanding of hematopoietic differenti ation; however, application of this technique is limited by the need t o use adherent cells as microcell donors, by the need to tag candidate chromosomes with a selectable marker, and by the need for prolonged s election of fused cells prior to characterization of their phenotype. We developed a modified technique of microcell fusion using square wav e electroporation, which allows higher efficiency fusion than polyethy lene glycol fusion. By using cross-species fusion and species-specific PCR primers, we were able to detect new gene induction events 48 h af ter microcell fusion. To study erythroid gene expression, we fused mic rocells from human erythroid K562 cells to murine B-lymphoid SP-2 cell s. We found that microcell fusion induced the nonerythroid recipient c ells to express alpha-globin mRNA in a dose-dependent manner. They als o expressed RNA. for beta-globin, GATA-1, and NF-EB. In contrast, ther e was no expression of heart- or liver-specific genes. We conclude tha t microcells from erythroid cells contain all the information necessar y to induce expression of multiple erythroid genes, Analysis of the co mponents of the microcells responsible for this new gene induction may allow the characterization of cellular factors responsible for erythr oid-specific gene expression. (C) 1997 Academic Press.