GSE60237
A hyper-dynamic nature of bivalent promoter states underlies coordinated developmental gene expression modules
Adipose stem cells (ASCs) and adipocytes play a crucial role in maintaining energy balance. We aim to examine the temporal relationship between gene expression and histone modification transitions during in vitro differentiation of human ASCs into adipocytes. Here, we examine by RNAseq proliferating ASCs (Day -2 prior to adipogenic induction), confluent ASCs (Day 0, adipogenic induction), pre-adipocytes (Day 3) and maturing adipocytes (Day 9). We find 1060, 5452 and 2216 genes differentially expressed between D-2/D0, D0/D3 and D3/D9 respectively. We identify gene clusters with distinct and dynamic expression patterns. In particular, adipogenic induction is marked by temporal waves of gene induction and downregulation. We report two types of transcriptional waves: (i) those showing transient induction or inactivation at D0, D3 or D9, and involved in sensory perception and immune response functions; and (ii) those showing long-lived induction or repression at these time points. Our data reveal a dynamic network of gene regulation during adipogenesis, involving signaling, immune and developmental processes. We identify 15 unique epigenetic states using Hidden Markov Modeling which reflects an epigenetically highly organised genome showing enhancer states are commonly consecutive. A heatmap for the abundance of epigenetic states for the expression clusters reveals a link between expression and epigenetic marking of the state suggesting an increase in the number of number of chromatin states with increase in expression. Our data point to a model of increased epigenetic complexity associated with gene expression. Overall design: Examination of expression of profiles of ASCs across differentiation