title: BET Bromodomain Proteins Brd2, Brd3 and Brd4 Selectively Regulate Metabolic Pathways in the Pancreatic β-Cell.
abstract: Displacement of Bromodomain and Extra-Terminal (BET) proteins from chromatin has promise for cancer and inflammatory disease treatments, but roles of BET proteins in metabolic disease remain unexplored. Small molecule BET inhibitors, such as JQ1, block BET protein binding to acetylated lysines, but lack selectivity within the BET family (Brd2, Brd3, Brd4, Brdt), making it difficult to disentangle contributions of each family member to transcriptional and cellular outcomes. Here, we demonstrate multiple improvements in pancreatic β-cells upon BET inhibition with JQ1 or BET-specific siRNAs. JQ1 (50-400 nM) increases insulin secretion from INS-1 cells in a concentration dependent manner. JQ1 increases insulin content in INS-1 cells, accounting for increased secretion, in both rat and human islets. Higher concentrations of JQ1 decrease intracellular triglyceride stores in INS-1 cells, a result of increased fatty acid oxidation. Specific inhibition of both Brd2 and Brd4 enhances insulin transcription, leading to increased insulin content. Inhibition of Brd2 alone increases fatty acid oxidation. Overlapping yet discrete roles for individual BET proteins in metabolic regulation suggest new isoform-selective BET inhibitors may be useful to treat insulin resistant/diabetic patients. Results imply that cancer and diseases of chronic inflammation or disordered metabolism are related through shared chromatin regulatory mechanisms.
authors.affiliation: Department of Medicine, Section of Endocrinology, Obesity Research Center, Evans Biomedical Research Center; Boston University School of Medicine, 650 Albany Street, X804, Boston, Massachusetts 02118, United States of America.
authors.forename: Jude T
authors.initials: JT
authors.lastname: Deeney
authors.affiliation: Flow Cytometry Core Facility, Boston University School of Medicine, 650 Albany Street, X326, Boston, Massachusetts 02118, United States of America.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Belkina
authors.affiliation: Department of Medicine, Section of Endocrinology, Obesity Research Center, Evans Biomedical Research Center; Boston University School of Medicine, 650 Albany Street, X804, Boston, Massachusetts 02118, United States of America.
authors.forename: Orian S
authors.initials: OS
authors.lastname: Shirihai
authors.affiliation: Department of Medicine, Section of Endocrinology, Obesity Research Center, Evans Biomedical Research Center; Boston University School of Medicine, 650 Albany Street, X804, Boston, Massachusetts 02118, United States of America.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Corkey
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, and Section of Hematology/ Oncology, Cancer Research Center; Boston University School of Medicine, 72 East Concord Street, K520, Boston, Massachusetts 02118, United States of America.
authors.forename: Gerald V
authors.initials: GV
authors.lastname: Denis
mesh_terms: D000818:Animals; D002460:Cell Line; D055785:Gene Knockdown Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D051381:Rats
chemical_list: D007328:Insulin; D017346:Protein Serine-Threonine Kinases