Characterization of a region of the X chromosome of Drosophila including multi sex combs (mxc), a Polycomb group gene which also functions as a tumour suppressor

Mol Gen Genet. 1995 Feb 6;246(3):282-90. doi: 10.1007/BF00288600.


Genetic analysis of the 8D3;8D8-9 segment of the Drosophila melanogaster X chromosome has assigned seven complementation groups to this region, three of which are new. A Polycomb group (Pc-G) gene, multi sex combs (mxc), is characterized and mutant alleles are described. Besides common homeotic transformations characteristic of Pc-G mutants that mimic the ectopic gain of function of BX-C and ANT-C genes, mxc mutants show other phenotypes: they zygotically mimic, in males and females, the characteristic lack of germ line seen in progeny of some maternal effect mutants of the so-called posterior group (the grandchildless phenotype). Loss of normal mxc function can promote uncontrolled malignant growth which indicates a possible relationship between Pc-G genes and tumour suppressor genes. We propose that gain-of-function of genes normally repressed by the wild-type mxc product could, in mxc mutants, give rise to an incoherent signal which would be devoid of meaning in normal development. Such a signal could divert somatic and germ line development pathways, provoke the loss of cell affinities, but allow or promote growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Crosses, Genetic
  • Drosophila Proteins*
  • Drosophila melanogaster / genetics*
  • Drosophila melanogaster / growth & development
  • Female
  • Genes, Dominant
  • Genes, Insect / physiology*
  • Genes, Lethal
  • Genes, Tumor Suppressor / physiology*
  • Infertility, Female / genetics
  • Infertility, Male / genetics
  • Male
  • Mutagenesis
  • Phenotype
  • Polycomb Repressive Complex 1
  • Proteins / genetics*
  • X Chromosome*


  • Drosophila Proteins
  • Pc protein, Drosophila
  • Proteins
  • Polycomb Repressive Complex 1