Epigenetic modifications and mRNA levels of the imprinted gene Grb10 in serially passaged fibroblast cells.

The imprinted gene Grb10 influences fetal growth, adult behavior and tumor formation. Investigating this gene often involves consecutive passaging of cells in vitro. We analyzed changes in Grb10 DNA methylation and histone modifications in serially passaged adult mouse tail-tip fibroblast cells with bisulfite genomic sequencing method and chromatin immunoprecipitation (ChIP) respectively. There was a significant reduction in global DNA methylation, but no changes in methylation at CpG island 1 (CGI1) of Grb10. There were no changes in methylation at histone H3K4me2, but less methylated histone H3K27me3 was detected, along with more of the acetylated histones H3Ac and H4Ac. The major-type transcript level of Grb10 in fibroblasts increased mildly after extended cultivation. These results suggest consecutive passaging may affect epigenetic modifications of Grb10 in adult fibroblast cells.