Biotechnology Centre; University College Dublin
The human MAS proto-oncogene is situated at 6q25.3-26, a region which is homologous to mouse chromosome 17 where two parentally imprinted genes (Mas and Igf2r) have been identified. Although reports indicate that Mas is expressed in mouse and rat testis and brain, there is no evidence to date of its expression or imprinting phenotype in adult human tissue.
MAS expression was assessed using a nested PCR approach. Allelic usage of MAS was determined by sequence analysis of a transcribable polymorphic marker (C900T base-pair substitution). This enabled the differentiation of parental alleles at the transcriptional level. Of 14 breast samples demonstrating a MAS RT PCR product, 4 were informative for the C900T marker. In all 4 cases, MAS expression was mono-allelic indicating the presence of a functional imprint at this locus in human breast tissue. In conclusion, our findings demonstrate firstly that MAS is expressed in breast tissue, secondly, similar to mice, expression is mono-allelic. (The work was sponsored by The Health Research Board, Ireland and the Mater College Foundation Ireland)