Extinction of hematopoietic specific transcription factor genes in cell hybrids between hematopoietic and non-hematopoietic cells

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We previously reported that expression of T cell receptor/CD3 genes in cell hybrids between mouse T lymphoma cells and fibroblasts (Mol.Cell biol., 13 : 1943-195,1993 ; Eur.J.Immunol., 25 : 2710-2713,1995). In athe present study, we have found expression of the 1ck gene and the immunoglobulin (Ig) gene was suppressed in T x fibroblast and B x embryonal carcinoma (EC) cell hybrids, respectively. The targets of the suppression were their enhancers and promoters. Expression of the hematopoietic transcription factor genes responsible for TCR/CD3 and Ig promoters and enhancers, such as the LEF-1, GATA-3, Ikaros/LyF-1, c-myb, Elf-1, PU./Spi-B,c-Ets-1, Oct-2and OCABgenes, was extinguished or suppressed in the hybrids, while expression of ubiquitously expressed transcription factor genes was not suppressed at all in the hybrids.These results suggest that putative repressors in non-hematopoietic cells shut off the expression of several hematopoietic cell-specific transcription factors and consequentlydownregulate expression of the lymphoid-specific structural genes.