Molecular Bases of Dominant Negative and Loss of Function Mutations at the Murine c-kit/white Spotting Locus: W37, Wv, W41 and W

EMBO J. 1990 Jun;9(6):1805-13.

Abstract

The proto-oncogene c-kit encodes a transmembrane tyrosine protein kinase receptor for an unknown ligand and is allelic with the murine white-spotting locus (W). Mutations at the W locus affect various aspects of hematopoiesis, the proliferation and migration of primordial germ cells and melanoblasts during development. The original W mutation and W37 are severe lethal mutations when homozygous. In the heterozygous state the W mutation has a weak phenotype while W37 has dominant characteristics. Wv and W41 are weak W mutations with dominant characteristics. We have characterized the molecular basis of these four W mutations and determined their effects on mast cell differentiation by using a fibroblast/mast cell co-culture assay. We show that W37, Wv and W41 are the result of missense mutations in the kinase domain of the c-kit coding sequence (W37 E----K at position 582; Wv T----M position 660 and W41 V----M position 831), which affect the c-kit associated tyrosine kinase to varying degrees. The c-kit protein products in homozygous mutant mast cells are expressed normally, although the 160 kd cell membrane form of the c-kitW37 protein displays accelerated turnover characteristics. The W mutation is the result of a 78 amino acid deletion which includes the transmembrane domain of the c-kit protein. A 125 kd c-kit protein was detected in homozygous W/W mast cells which lacks kinase activity and is not expressed on the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cells, Cultured
  • Chromosome Mapping
  • Fibroblasts / physiology
  • Mast Cells / physiology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Mutation*
  • Phenotype
  • Pigmentation / genetics
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism*
  • Proto-Oncogene Proteins / biosynthesis
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins c-kit
  • RNA, Messenger / biosynthesis

Substances

  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Protein-Tyrosine Kinases
  • Proto-Oncogene Proteins c-kit