Nutrient regulation of the islet epigenome controls adaptive insulin secretion

Adaptation of the islet β-cell insulin secretory response to changing insulin demand is critical for blood glucose homeostasis, yet the mechanisms underlying this adaptation are unknown. Here, we have shown that nutrient-stimulated histone acetylation plays a key role in adapting insulin secretion through regulation of genes involved in β-cell nutrient sensing and metabolism. Nutrient regulation of the epigenome occurred at sites occupied by the chromatin-modifying enzyme Lysine-specific demethylase 1 (Lsd1) in islets. β-cell-specific deletion of Lsd1 led to insulin hypersecretion, aberrant expression of nutrient response genes, and histone hyperacetylation. Islets from mice adapted to chronically increased insulin demand exhibited shared epigenetic and transcriptional changes. Moreover, we found that genetic variants associated with type 2 diabetes were enriched at LSD1-bound sites in human islets, suggesting that interpretation of nutrient signals is genetically determined and clinically relevant. Overall, these studies revealed that adaptive insulin secretion involves Lsd1-mediated coupling of nutrient state to regulation of the islet epigenome

Alicyclobacillus tengchongensis sp. nov., a thermo-acidophilic bacterium isolated from hot spring soil

A thermo-acidophilic bacterium, designated strain ACK006T, was isolated from the soil of a hot sp.ing at Tengchong in China. Cells were Gram-staining-positive, motile, catalasepositive and oxidase-negative, sp.re-forming rods. The isolate grew aerobically at 30-50°C (optimum at 45°C), pH 2.0-6.0 (optimum pH 3.2) and 0-5.0% (w/v) NaCl (optimum 1% NaCl). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain ACK006T belongs to the genus Alicyclobacillus with the sequence similarity of 92.3, 92.4, 92.5, and 92.8% to Alicyclobacillus cycloheptanicus SCHT, Alicyclobacillus ferrooxydans TC-34T, Alicyclobacillus contaminans 3-A191T and Alicyclobacillus disulfidooxidans SD-11T, respectively. Similarity to other sp.cies of the genus Alicyclobacillus was 90.3-92.8% and similarity to sp.cies of the genus Tumebacillus was 85.9-87.8%. The genomic DNA G+C content was 53.7 mol%. The predominant menaquinone was MK-7. Major fatty acids were ω-cycloheptane C18:0, iso-C17:0 and anteiso-C17:0. The cell-wall peptidoglycan was the Alγ type; containing meso-diaminopimelic acid as the diagnostic diamino acid. On the basis of polyphasic analysis from this study, strain ACK006T represents a nov.l sp.cies of the genus Alicyclobacillus for which the name Alicyclobacillus tengchongensis sp. nov. is proposed. The type strain is ACK006T (=KCTC 33022T =DSM 25924T).open