The AlkB family of demethylases; putative roles in embryonic stem cell identity and epigenetic reprogramming of the germ line.

This project is initiated primarily based upon the intriguing phenotype and breeding pattern of Alkbh (AlkB homologs) targeted mice. Targeting of mouse Alkbh's (8 in total) cause various degree of sex-ratio distortion and developmental abnormalities incl uding asymmetric left-right eye development. Alkbh1 is highly expressed in embryonic stem (ES) cells and the promoter of the gene is occupied by Oct4 and Nanog, two essential regulators of early development and ES cell identity (Boyer et al., Cell, 2005, 122, 947-956). Furthermore, there are some remarkable similarities between the different AlkB homologs. First, it has been proposed that the very low pI of Alkbh1, 4 and 7 makes them likely candidates for being histone demethylases (Sedgwick et al., DNA r epair, 2007, 6, 429-442). We have shown that these three homologs are dramatically upregulated in pachytene, the third stage of the prophase of male meiosis. All AlkB homologs, apart from homologs 2, 3 and 8 which have known or putative activities for DNA and RNA and therefore are not a part of this proposal, contains a CpG island spanning most of, or the entire, exon 1 (Figure 1). Subprojects include assessing the roles of the remaining Alkb homologs in pluripotent stem cells and germ cells. Experiments are also planned in order to identify their putative roles in hydroxylating histone methyl groups and 5-methyl cytosine in DNA.