Mutagenesis vol. 19 no. 4 pp. 263-268,
July 2004
© 2004 UK Environmental Mutagen Society/Oxford University Press
Loss of P53 heterozygosity is not responsible for the small colony thymidine kinase mutant phenotype in L5178Y mouse lymphoma cells
University of North Carolina Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC, USA, 1Environmental Carcinogenesis Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA, 2Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA and 3Toxicology and Molecular Biology Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
The mouse lymphoma L5178Y Tk+/– 3.7.2C assay is a well-characterized in vitro system used for the study of somatic cell mutation. It was determined that this cell line has a heterozygous mutation in exon 5 of Trp53. Based on this assumption that the cell line is heterozygous for the Trp53 gene, it was postulated that the small colony thymidine kinase (Tk) mutant phenotype may be due to a newly induced mutation/deletion in both the Trp53 and Tk1 alleles. The resultant Tk–/– mutants would also be Trp53+/0 or Trp53+/+ and would lose their ability to grow at normal rates. Subsequently, we published our evaluation of the Trp53 status in L5178Y cells. This analysis included sequencing of Trp53 exon 4 and determined that the mouse lymphoma cell line has a mutation in both of the Trp53 alleles and, therefore, no wild-type Trp53 allele in either Tk+/– cells or Tk–/– mutants. Because the cells have no wild-type Trp53, it is not possible that the small colony phenotype results from a newly induced loss of both functional Trp53 and Tk. To determine whether small colonies might, however, include the deletion of both Trp53 and Tk we evaluated, using microsatellite marker analysis, a series of small colony mutants. We also utilized in situ hybridization to determine that the Trp53 alleles are, in fact, in their normal chromosome 11 location in Tk+/– 3.7.2C mouse lymphoma cells. From all of these analyses we can conclude that the small colony mutant phenotype is not caused by deletion of both Trp53 and Tk1.
4To whom correspondence should be addressed at: Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, HFT 120, 3900 NCTR Road, Jefferson, AR 72079, USA. Tel: +1 870 543 7050; Fax: +1 870 543 7393; Email: mmmoore{at}nctr.fda.gov
Received on August 16, 2002; revised on February 6, 2004; accepted on March 5, 2004
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. Wang, J. R. Sawyer, L. Chen, T. Chen, M. Honma, N. Mei, and M. M. Moore The Mouse Lymphoma Assay Detects Recombination, Deletion, and Aneuploidy Toxicol. Sci., May 1, 2009; 109(1): 96 - 105. [Abstract] [Full Text] [PDF]
|
|