H3K4 Trimethylation Is Required for Postnatal Pancreatic Endocrine Cell Functional Maturation

Abstract

Facility and ethical procedures were followed according to protocols approved by the University of British Columbia Animal Care Committee. All mice were maintained on a regular chow diet ad libitum and housed up to 5 mice per cage on a 12-hour light/dark cycle. Timed matings were used to determine embryonic stages and the morning of vaginal plug discovery was considered embryonic day 0.5 (E0.5). Previously generated Dpy30 flox/flox mice ( 22) were crossed to Neurog3-Cre driver mice ( 23) to obtain conditional deletion of Dpy30 exon 4 in endocrine progenitors. In all studies, knockout mice (Dpy30N; Neurog3-Cre; Dpy30 flox/flox ) were compared to Cre-negative littermate controls (Dpy30 flox/flox or Dpy30 flox/wt ). At noon on the day

Methylation of histone H3 lysine 4 is required for maintenance of beta cell function in adult mice

“…Following washing with PBS and dehydration in ethanol and xylenes, mouse tissues were embedded in paraffin and sectioned with a thickness of 5 μm. Immunofluorescent analyses of tissue sections was performed as previously described 23 in a blinded fashion from 4-6 sections per biological sample. Primary antibodies used were: H3K4me3 (Cell Signaling Technologies, C42D8, 1:500), H3K4me1 (Abcam, ab8895, 1:1,000), H3 (Abcam, ab1791, 1:1,000), DPY30 (Atlas Antibodies, HPA043761, 1:500), Insulin (Agilent, IR-002, 1:4), and Glucagon (Sigma Aldrich, G2654, 1:1,000).…”

“…We previously defined roles for DPY30 during embryonic pancreas development. DPY30 fine-tunes cell fate decisions to decrease endocrine acinar cell specification in favour of exocrine cell specification 21 and helps to activate terminal marker genes during endocrine cell maturation 23 . By contrast, it is not known whether the continuous activity of H3K4 methyltransferases is necessary in terminally differentiated islet cells, where lineage-specific transcription programs have already been established.…”

Lessons from neonatal β-cell epigenomic for diabetes prevention and treatment

“…These epigenetic mechanisms are crucial for activating the expression of genes controlling metabolism and proliferation of immature -cell during the breastfeeding period [32,33]. In immature -cells, the expression of genes involved in cell cycle control and in anaerobic glycolysis correlates with changes in histone 3 trimethylation at lysine 27 and 4 (H3K27me3 and H3K4me3, respectively) [34][35][36]. H3K4 trimethylation at gene promoters and distal regulatory enhancers favours the recruitment of the transcription machinery and of chromatin remodelling complexes [37] and is generally accompanied by H3K27 acetylation and low levels of the repressive H3K27me3 marks.…”

“…Moreover, glucose promotes important changes in the DNA methylation profile of many genes [55]. In mice, increased expression of genes controlling glucose-induced insulin secretion including Znt8, NeuroD1, Glut2, Urocortin 3 (Ucn3) and Kir6.2 relies on H3K4 trimethylation [36]. Elevated transcription of Pdx1, Abcc8, Syt4/7 and Snap25 has been associated with chromatin opening due to H3K27me3.…”

Mechanisms Underlying the Expansion and Functional Maturation of β-Cells in Newborns: Impact of the Nutritional Environment

“…The expression profile of numerous key transcription factors also depends on the methylation status of the genome and the subsequent stability of the transcriptome. The activity of histone methyltransferases such as RNA methyltransferase-like 3/14 (METTL3/14) and Histone H3 lysine K4 (H3K4) has been shown to be essential both for terminal differentiation and expansion of β-cells in the postnatal period via the regulation of the expression of Mafa [42,43].…”