Involvement of the clock gene Rev-erb alpha in the regulation of glucagon secretion in pancreatic alpha-cells

• Published in: PloS one Vol. 8; no. 7; p. e69939
• Main Authors: Vieira, Elaine, Marroquí, Laura, Figueroa, Ana Lucia C, Merino, Beatriz, Fernandez-Ruiz, Rebeca, Nadal, Angel, Burris, Thomas P, Gomis, Ramon, Quesada, Ivan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-07-2013; Public Library of Science (PLoS)
• Subjects: AMP-Activated Protein Kinases - genetics; AMP-Activated Protein Kinases - metabolism; Animals; Beta cells; Biology; Calcium; Calcium (intracellular); Calcium signalling; Cell cycle; Cell Line; Circadian rhythm; Circadian Rhythm - genetics; Circadian rhythms; Citoquines; Clock gene; CLOCK protein; Cytokines; Cytokines - genetics; Cytokines - metabolism; Diabetes; Diabetes mellitus; Endocrinology; Exocytosis; Gene expression; Gene Expression Regulation; Genes; Genètica humana; Glucagon; Glucagon - genetics; Glucagon - metabolism; Glucagon - secretion; Glucagon-Secreting Cells - cytology; Glucagon-Secreting Cells - drug effects; Glucagon-Secreting Cells - secretion; Glucosa; Glucose; Glucose - metabolism; Glucose - pharmacology; Glycine - analogs & derivatives; Glycine - pharmacology; Homeostasis; Human genetics; Inhibition; Insects; Intracellular; Isoquinolines - pharmacology; Kinases; Laboratories; Machinery; Machinery and equipment; Medicine; Metabolism; Metformin; Metformin - pharmacology; Mice; Nicotinamide Phosphoribosyltransferase - genetics; Nicotinamide Phosphoribosyltransferase - metabolism; Nuclear Receptor Subfamily 1, Group D, Member 1 - agonists; Nuclear Receptor Subfamily 1, Group D, Member 1 - antagonists & inhibitors; Nuclear Receptor Subfamily 1, Group D, Member 1 - genetics; Nuclear Receptor Subfamily 1, Group D, Member 1 - metabolism; Obesity; Pancreas; Pàncrees; RNA; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Rodents; Secretion; Signal Transduction; siRNA; SIRT1 protein; Sirtuin 1 - genetics; Sirtuin 1 - metabolism; Thiophenes - pharmacology; Type 2 diabetes; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0069939

Disruption of pancreatic clock genes impairs pancreatic beta-cell function, leading to the onset of diabetes. Despite the importance of pancreatic alpha-cells in the regulation of glucose homeostasis and in diabetes pathophysiology, nothing is known about the role of clock genes in these cells. Here, we identify the clock gene Rev-erb alpha as a new intracellular regulator of glucagon secretion. Rev-erb alpha down-regulation by siRNA (60-70% inhibition) in alphaTC1-9 cells inhibited low-glucose induced glucagon secretion (p<0.05) and led to a decrease in key genes of the exocytotic machinery. The Rev-erb alpha agonist GSK4112 increased glucagon secretion (1.6 fold) and intracellular calcium signals in alphaTC1-9 cells and mouse primary alpha-cells, whereas the Rev-erb alpha antagonist SR8278 produced the opposite effect. At 0.5 mM glucose, alphaTC1-9 cells exhibited intrinsic circadian Rev-erb alpha expression oscillations that were inhibited by 11 mM glucose. In mouse primary alpha-cells, glucose induced similar effects (p<0.001). High glucose inhibited key genes controlled by AMPK such as Nampt, Sirt1 and PGC-1 alpha in alphaTC1-9 cells (p<0.05). AMPK activation by metformin completely reversed the inhibitory effect of glucose on Nampt-Sirt1-PGC-1 alpha and Rev-erb alpha. Nampt inhibition decreased Sirt1, PGC-1 alpha and Rev-erb alpha mRNA expression (p<0.01) and glucagon release (p<0.05). These findings identify Rev-erb alpha as a new intracellular regulator of glucagon secretion via AMPK/Nampt/Sirt1 pathway.