Demethylation of Epiregulin Gene by Histone Demethylase FBXL11 and BCL6 Corepressor Inhibits Osteo/dentinogenic Differentiation

Mesenchymal stem cells (MSCs) are a reliable resource for tissue regeneration, but the molecular mechanism underlying directed differentiation remains unclear; this has restricted potential MSC applications. Histone methylation, controlled by histone methyltransferases and demethylases, may play a key role in MSC differentiation. Here, we investigated FBXL11, a histone demethylase, lysine (K)-specific demethylase 2A, which is evolutionarily conserved, ubiquitously expressed, and a member of the JmjC-domain-containing histone demethylase family. We tested whether FBXL11 could inhibit the osteo/dentinogenic differentiation potential in MSC cells with gain-and loss-of-function assays. We found that FBXL11 regulated osteo/dentinogenic differentiation in MSC cells. Furthermore, we found that the gene encoding the epidermal growth factor, Epiregulin (EREG), was a downstream target of FBXL11, and that EREG mediated FBXL11 regulation of MSC differentiation. Moreover, we found that the FBXL11 histone demethylase function was activated by associating with BCL6 corepressor, and this complex could repress EREG transcription by increasing histone K4/36 methylation in the EREG promoter. In conclusion, our results elucidated a new function for FBXL11 and EREG, explored the molecular mechanism underlying directed differentiation in MSC cells, and identified potential target genes for improving tissue regeneration techniques. STEM CELLS 2013;31:126-136