In vivo loss of heterozygosity in T-cells of B6C3F1 Aprt+/− mice

✍ Scribed by Li Liang; Li Deng; Changshun Shao; Peter J. Stambrook; Jay A. Tischfield

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 77 KB
• Volume: 35
• Category: Article
• ISSN: 0893-6692
• DOI: 10.1002/(sici)1098-2280(2000)35:2<150::aid-em10>3.0.co;2-0

✦ Synopsis

We have used B6C3F1 mice heterozygous at Aprt (adenine phosphoribosyltransferase) as a model to study in vivo loss of heterozygosity (LOH) in normal splenic T-lymphocytes. APRT-deficient T-cells were selected in medium containing 50 g/ml 2,6-diaminopurine (DAP), an adenine analog that is toxic only to cells with APRT enzyme activity. DAP-resistant (DAP r ) T-cell variants were recovered at an average frequency of 3 ϫ 10 Ϫ5 from 21 B6C3F1 Aprt ϩ/Ϫ mice. Allele-specific PCR of Aprt showed that about 70% of 122 DAP r colonies were caused by loss of the nontargeted Aprt allele (Aprt ϩ ). Anal- ysis of microsatellite markers along the length of chromosome 8 suggested that mitotic recombina-tion, or chromosome loss, with or without duplication of the remaining chromosome are the predominant mechanisms resulting in loss of Aprt ϩ . DNA sequencing of Aprt RT-PCR products from the DAP r variants that retained Aprt ϩ indicated that point mutation as well as other mechanisms could cause this second class of variants. The high spontaneous frequency of in vivo Aprt LOH in mouse T-cells, mediated by LOH mechanisms that are also known to produce human cancers, suggests that the Aprt heterozygous mouse is a valid model for studying the diversity of mechanisms for in vivo somatic mutagenesis.