Involvement of the clock gene Rev-erb alpha in the regulation of glucagon secretion in pancreatic alpha-cells.
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.
Instituto de Bioingeniería, Universidad Miguel Hernandez de Elche, Elche, Spain. evieira@ciberdem.org
Elaine
E
Vieira
Laura
L
Marroquí
Ana Lucia C
AL
Figueroa
Beatriz
B
Merino
Rebeca
R
Fernandez-Ruiz
Angel
A
Nadal
Thomas P
TP
Burris
Ramon
R
Gomis
Ivan
I
Quesada
D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002940:Circadian Rhythm / Q000235:genetics*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D005934:Glucagon / Q000235:genetics / Q000378:metabolism*; D050416:Glucagon-Secreting Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D054409:Nicotinamide Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism; D056953:Nuclear Receptor Subfamily 1, Group D, Member 1 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism; D013876:Thiophenes / Q000494:pharmacology
D016207:Cytokines; C572356:GSK4112; D007546:Isoquinolines; C498262:Nr1d1 protein, mouse; D056953:Nuclear Receptor Subfamily 1, Group D, Member 1; D034741:RNA, Small Interfering; C558456:SR 8278; D013876:Thiophenes; D005934:Glucagon; D008687:Metformin; D054409:Nicotinamide Phosphoribosyltransferase; C495867:nicotinamide phosphoribosyltransferase, mouse; D055372:AMP-Activated Protein Kinases; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1; D005947:Glucose; D005998:Glycine