Epigenetic regulation of nestin expression during neurogenic differentiation of adipose tissue stem cells

Abstract

Adipose-tissue-derived stem cells (ASCs) have received considerable attention due to their easy access, expansion potential, and differentiation capacity. ASCs are believed to have the potential to differentiate into neurons. However, the mechanisms by which this may occur remain largely unknown. Here, we show that culturing ASCs under active proliferation conditions greatly improves their propensity to differentiate toward osteogenic, adipogenic, and neurogenic lineages. Neurogenic-induced ASCs express early neurogenic genes as well as markers of mature neurons, including voltage-gated ion channels. Nestin, highly expressed in neural progenitors, is upregulated by mitogenic stimulation of ASCs, and as in neural progenitors, then repressed during neurogenic differentiation. Nestin gene (NES) expression under these conditions appears to be regulated by epigenetic mechanisms. The neural-specific, but not muscle-specific, enhancer regions of NES are DNA demethylated by mitogenic stimulation, and remethylated upon neurogenic differentiation. We observe dynamic changes in histone H3K4, H3K9, and H3K27 methylation on the NES locus before and during neurogenic differentiation that are consistent with epigenetic processes involved in the regulation of NES expression. We suggest that ASCs are epigenetically prepatterned to differentiate toward a neural lineage and that this prepatterning is enhanced by demethylation of critical NES enhancer elements upon mitogenic stimulation preceding neurogenic differentiation. Our findings provide molecular evidence that the differentiation repertoire of ASCs may extend beyond mesodermal lineages.