Sex and Tissue Specificity of Peg3 Promoters

The expression of mouse Peg3 (Paternally expressed gene 3) is driven by 4 promoters, including its main and three alternative promoters. The sexual, temporal and spatial specificity of these promoters was characterized in the current study. According to the results, the main promoter displays ubiquitous expression patterns throughout different stages and tissues. In contrast, the expression of Peg3 driven by the alternative promoter U2 was detected mainly in muscle and skin, but not in brain, starting from the late embryonic stage, revealing its tissue and stage specificity. The expression levels of both the main and U2 promoters are also sexually biased: the levels in females start higher but become lower than those in males during early postnatal stages. As an imprinted locus, the paternal alleles of these promoters are active whereas the maternal alleles are silent. Interestingly, deletion of the repressed maternal allele of the main promoter has an unusual effect on the opposite paternal allele, causing the up-regulation of both the main and U2 promoters. Overall, the promoters of Peg3 derive sexually biased and tissue-specific expression patterns.