Two mechanisms for the extinction of gene expression in hybrid cells

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Science  02 Sep 1988:
Vol. 241, Issue 4870, pp. 1205-1207
DOI: 10.1126/science.2842865


When two different mammalian cell types are fused to generate a stable hybrid cell line, genes that are active in only one of the parents are frequently shut off, a phenomenon called extinction. In this study two distinct, complementary mechanisms for such extinction of growth hormone gene expression were identified. In hybrids formed by fusing fibroblasts to pituitary cells, pituitary-specific proteins that bind to the growth hormone promoter were absent. In addition, a negative regulatory element located near the rat growth hormone promoter was specifically activated.