Epigenetic regulation of neurogenic differentiation of adipose tissue stem cells

Abstract

Mesenchymal stem cells (MSCs) derived from adipose tissue are multipotent stem cells able to give rise into multiple cell types, not only of the mesodermal lineage, but also of the neuroectodermal lineage. In this study, we show that there is an epigenetic basis related to the capacity of adipose tissue stem cells (ASCs) to differentiate towards the neurogenic pathway. Neurogenic differentiation was induced by a step of mitogenic stimulation (step 1), followed by neurogenic induction (step 2), and shown at the gene and protein expression levels. Nestin has been extensively used as a marker for neurogenesis. The DNA methylation status of several regions of the nestin (NES) gene, including the promoter, a muscle-specific enhancer in the first intron, and a neural enhancer in the second intron, was determined by bisulphite genomic sequencing prior to and after induction of proliferation (step 1) and neurogenic differentiation (step 2). There was a global demethylation of the second intron upon proliferation induction and this was followed by a strong upregulation of nestin expression at the mRNA and protein level. We observed re-methylation of these regions after induction of neurogenic differentiation in vitro, and that was accompanied by a steep decline in nestin expression at the mRNA and protein level. These data are consistent with nestin being a marker of early neurogenesis. Analysis of post-translational histone modifications by chromatin immunoprecipitation reveals dynamic changes at the NES locus and on the promoter of a housekeeping gene (GAPDH) associated with step 1 and step 2. Our data suggest an epigenetic ‘priming’ of ASCs (at least at the NES locus) towards neurogenic differentiation, which is primarily elicited by mitogenic stimulation.