The nuclear orphan receptor Nur77 is a lipotoxicity sensor regulating glucose-induced insulin secretion in pancreatic β-cells.
The NR4A orphan nuclear receptors Nur77, Nurr1, and Nor1 exert multiple cellular and metabolic functions. These transcriptional regulators are activated in response to extracellular stresses, including lipotoxic fatty acids (FA) and proinflammatory cytokines. The contribution of NR4As to β-cell pathophysiology is, however, unknown. We have therefore examined the role of NR4As as downstream contributors to FA-induced β-cell dysfunctions. Human pancreatic islets and insulinoma β-cells were used to determine transcriptional programs elicited by NR4A, which were compared to those triggered by palmitate treatment. Functional studies evaluated the consequence of an increased NR4A expression on insulin biosynthesis and secretion and cell viability in insulinoma β-cells. FA and cytokine treatment increased NR4A expression in pancreatic β-cells, with Nur77 being most highly inducible in murine β-cells. Nur77, Nurr1, or Nor1 modulated common and distinct clusters of genes involved notably in cation homeostasis and insulin gene transcription. By altering zinc homeostasis, insulin gene transcription, and secretion, Nur77 was found to be a major transcriptional mediator of part of FA-induced β-cell dysfunctions. The repressive role of Nur77 in insulin gene regulation was tracked down to protein-protein interaction with FoxO1, a pivotal integrator of the insulin gene regulatory network. The present study identifies a member of the NR4A nuclear receptor subclass, Nur77/NR4A1, as a modulator of pancreatic β-cell biology. Together with its previously documented role in liver and muscle, its role in β-cells establishes Nur77 as an important integrator of glucose metabolism.
Institut Pasteur de Lille, Faculté de Médecine de Lille-Pôle Recherche; Institut National de la Santé et de la Recherche Médicale (INSERM) U1011-Bâtiment J&K; Boulevard du Pr Leclerc, Lille cedex, France.
Olivier
O
Briand
Audrey
A
Helleboid-Chapman
Maheul
M
Ploton
Nathalie
N
Hennuyer
Rodolphe
R
Carpentier
François
F
Pattou
Brigitte
B
Vandewalle
Ericka
E
Moerman
Valery
V
Gmyr
Julie
J
Kerr-Conte
Jérôme
J
Eeckhoute
Bart
B
Staels
Philippe
P
Lefebvre
D000818:Animals; D002460:Cell Line; D053379:Chromogranin A / Q000378:metabolism; D005227:Fatty Acids / Q000502:physiology; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051473:Maf Transcription Factors, Large / Q000235:genetics / Q000378:metabolism; D051379:Mice; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010179:Pancreas / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013312:Stress, Physiological
D053379:Chromogranin A; C085126:FOXO1 protein, human; D005227:Fatty Acids; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D007328:Insulin; C485159:MAFA protein, human; D051473:Maf Transcription Factors, Large; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D005947:Glucose