title: A genetic analysis of extinction: trans-regulation of 16 liver-specific genes in hepatoma-fibroblast hybrid cells.
abstract: Hybrid cells formed by fusing different cell types generally fail to express the tissue-specific products of either parent, a phenomenon termed extinction. We have investigated the generality of this effect by assaying hepatoma-fibroblast hybrids for expression of 16 different liver-specific mRNAs. Fourteen of the mRNAs failed to accumulate in karyotypically complete hybrid clones, and quantitative measurements indicated that steady-state mRNA levels were depressed by a factor of at least 500-1000. However, all 14 liver-specific mRNAs were reexpressed in the hybrids following fibroblast chromosome loss. These data indicate that expression of whole sets of tissue-specific genes is affected in trans in intertypic hybrids and suggest that negative regulation of heterologous functions may be common form of gene control.
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002874:Chromosome Mapping; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006822:Hybrid Cells / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012709:Serum Albumin / Q000235:genetics; D014444:Tyrosine Transaminase / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D012709:Serum Albumin; D000426:Alcohol Dehydrogenase; D014444:Tyrosine Transaminase; D010729:Phosphoenolpyruvate Carboxykinase (GTP)