In vivo loss of heterozygosity in T-cells of B6C3F1 Aprt(+/-) mice.
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 microg/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 x 10(-5) from 21 B6C3F1 Aprt(+/-) 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(+)). Analysis of microsatellite markers along the length of chromosome 8 suggested that mitotic recombination, or chromosome loss, with or without duplication of the remaining chromosome are the predominant mechanisms resulting in loss of Aprt(+). DNA sequencing of Aprt RT-PCR products from the DAP(r) variants that retained Aprt(+) 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.
Liang
L
L
Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
Deng
L
L
Shao
C
C
Stambrook
P J
PJ
Tischfield
J A
JA
D000228:Adenine Phosphoribosyltransferase / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D006801:Humans; D019656:Loss of Heterozygosity; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000201:enzymology*
D017931:DNA Primers; D000228:Adenine Phosphoribosyltransferase