GSE130651
Identification of Scrt1, a new transcriptional regulator of   beta-cell maturation using chromatin accessibility variations
Pancreatic beta-cells are highly specialized cells that produce and release insulin in response to nutrients, hormones and neurotransmitters. Glucose-induced insulin secretion, a unique feature of fully differentiated beta-cells, is only acquired after birth and is preceded by a phase of intense beta-cell proliferation. These events occurring in the neonatal period are critical for the establishment of an appropriate functional beta-cell mass covering the insulin needs throughout life. However, key regulators of gene expression and cis-regulatory elements involved in the cellular reprogramming along maturation remain to be elucidated. This project addresses this issue by using ATAC-seq (Assay for Transposase-Accessible Chromatin with high throughput sequencing) permitting a fine genome-wide mapping of chromatin accessibility. This approach is used to compare open chromatin regions in newborn and adult rat beta-cells. We obtained a genome-wide picture of chromatin accessible sites (100000) among which 20% were differentially accessible during maturation. Nearly 60% of these sites were in the proximity of significantly differentially expressed genes. An analysis of transcription factor binding sites revealed key known and unforeseen transcription factors which could explain these changes. We validated a transcriptional repressor named SCRT1, that depicted a significant effect on beta-cell proliferation and targeted several genes implicated in the acquisition of glucose-stimulated insulin secretion function. Thus, we were able to find several known and unforeseen key transcriptional regulators acting at cis-regulatory sites and promoters which depicted a differential accessibility and induced differential gene expression along maturation. These findings could be of interest to induce maturation of surrogate insulin-producing cells. Overall design: RNA-seq of FACS sorted pancreatic beta-cells of adult  rats with siSCRT1 and control (n=5).