title: Oncogenes and the mammalian X chromosome.
abstract: None of the up to now localized and expressed oncogenes maps to the mammalian X chromosome. This fact is discussed in the light of a trans-acting regulation mechanism for oncogenes. Such a specific regulation mechanism is demonstrated here for a qualitative change--i.e., varying timing of DNA-replication--at the putative c-myc gene locus in band 15E of murine T-cell leukemia. In intraspecific hybrids between tumor and non-tumor cells this qualitative change spreads over to all chromosomes 15 of the same cell, irrespective of their origin. This effect is thought to reflect a binary trans-acting regulation mechanism between homologous chromosomal loci. In the past specific chromosomal aberrations have been described in various tumors but none of these aberrations involve the X chromosome. For the mammalian X chromosome where there is usually only one gene copy per cell active the described kind of binary trans-acting regulation between homologous gene loci is rendered impossible.
mesh_terms: D000818:Animals; D002871:Chromosome Banding; D002874:Chromosome Mapping; D005799:Genes, Dominant; D008040:Genetic Linkage; D006801:Humans; D007621:Karyotyping; D009369:Neoplasms / Q000235:genetics*; D009857:Oncogenes; D014960:X Chromosome