Extinction of expression of immunoglobulin genes in myeloma X fibroblast somatic cell hybrids.

Genes activated in the presence of an immunoglobulin enhancer or promoter are negatively regulated by a T-lymphoma cell line.

“…Another kind of evidence for the negative regulation of immunoglobulin genes in non-B cells is the finding that IgH production generally ceases when B-derived cells are fused to either T cells or fibroblasts (9,19,25,40). This observation suggests the existence of a trans-acting negative regulator in non-B cells that can extinguish immunoglobulin gene expression even after the gene has been activated.…”

Novel regulation of transcription initiation of the peptide IX gene of adenovirus 2.

“…The importance of negative regulation in the transcription of eucaryotic genes is becoming increasingly apparent. The existence of repressor molecules was suggested originally by use of cell fusions between differentiated cell types and fibroblasts (2,7,12,22,30). Several lines of evidence indicate that negative regulation of transcription is involved in tissue-or cellspecific and inducible gene expression.…”

Extinction of expression of the translocated myc gene in somatic cell hybrids between mouse myeloma and l‐cells

“…Presence of the translocated myc gene in myeloma x fibroblast somatic cell hybrids All of the myeloma x fibroblast cell hybrids studied in the present report were previously shown to have an adherent phenotype and did not express the K or y Ig genes (Greenberg et al, 1987). Southern blot analysis shows that all of the tested hybrids retained the translocated myc gene derived from the parental myeloma cell (Fig.…”