Project description:Stem cell-derived islet (SC-islet) organoids offer hope for cell replacement therapy in diabetes, but their immature function remains a challenge. Mature islet function requires the β-cell circadian clock, yet how the clock regulates maturation is unclear. Here, we show that a circadian transcription factor specific to maturing SC-β cells, DEC1, regulates insulin responsiveness to glucose. SC-islet organoids form normally from DEC1-ablated human pluripotent stem cells, but their insulin release capacity and glucose threshold fail to increase during in vitro culture and upon transplant. This deficit reflects downregulation of maturity-linked effectors of glucose utilization and insulin exocytosis, blunting glycolytic and oxidative metabolism, and is rescued by increasing metabolic flux. Moreover, DEC1 is needed to boost SC-islet maturity by synchronizing circadian glucose-responsive insulin secretion rhythms and clock machinery. Thus, DEC1 links circadian control to human β-cell maturation, highlighting its vitality to foster fully functional SC-islets.
Project description:The transcription factor PAX6 is involved in the development of the eye and pancreatic islets, besides being associated with sleep-wake cycles. Here, we investigated a point mutation in the RED subdomain of PAX6, previously described in a human patient, to present a comprehensive study of a homozygous Pax6 mutation in the context of adult mammalian metabolism and circadian rhythm. Pax6Leca2 mice lack appropriate retinal structures for light perception and do not display normal daily rhythmic changes in energy metabolism. Despite β cell dysfunction and decreased insulin secretion, mutant mice have normal glucose tolerance. This is associated with reduced hepatic glucose production possibly due to altered circadian variation in expression of clock and metabolic genes, thereby evading hyperglycemia. Hence, our findings show that while the RED subdomain is important for β cell functional maturity, the Leca2 mutation impacts peripheral metabolism via loss of circadian rhythm, thus revealing pleiotropic effects of PAX6.
Project description:Identification of cyclical expressed coding and non-coding genes during the circadian rhythm in NIH3T3 cells. NIH3T3 cells were synchronized for their circadian rhythm and RNA sequencing were performed at several time points along the rhythm. This data was used to identify cyclical expressed genes as well as long intergenic non-coding RNAs.
Project description:Identification of cyclical expressed coding and non-coding genes during the circadian rhythm in NIH3T3 cells. NIH3T3 cells were synchronized for their circadian rhythm and RNA sequencing were performed at several time points along the rhythm. This data was used to identify cyclical expressed genes as well as long intergenic non-coding RNAs. NIH3T3 cells were synchronized with 100 nM Dexamethasone for 2 hours, then medium was changed to normal culture medium (0h). Every 4 hours cells were harvested, RNA isolated and RNAseq performed.
Project description:Molecular analysis of circadian rhythm in mice. Liver tissue of wildtype, Clock mutant and Cry deficient C57BL/6 8- to 10-week-old male mice examined. Keywords = circadian rhythm Keywords: other
Project description:The circadian clock attunes metabolism to daily energy cycles, but how it regulates metabolic tissue maturation is not well understood. Here we show that DEC1, a clock transcription factor induced in adult islet β cells, coordinates their glucose responsiveness by synchronizing energetic and secretory rhythms. DEC1 binds maturity-linked genes regulating integration of energy metabolism and insulin exocytosis, and β-cell Dec1 ablation disrupts their transcription synchrony. Dec1-disrupted mice develop lifelong glucose intolerance and insulin deficiency, despite normal islet formation and intact CLOCK/BMAL1 genes. Metabolic dysfunction upon β-cell Dec1 loss stems from poor coupling of insulin secretion to glucose metabolism, reminiscent of fetal/neonatal immaturity. We find that stunted maturation reflects an energetic deficit, marked by reduced glycolysis and compromised mitochondrial dynamics and respiration, which is rescued by increasing metabolic flux. Thus, DEC1 links circadian clockwork to β-cell metabolic maturation, revealing a hierarchy for how the clock programs metabolic tissue specialization.
Project description:The weaning period consist of a critical postnatal window for structural and physiologic maturation of rat beta cells. To investigate transcriptome changes involved in the maturation of beta cells neighboring this period we performed microarray analysis in FACS beta cell enriched populations to detail the global programme of gene expression to identify its changes during this process. Male Wistar rats were selected at the initial point of a postnatal critical period (postnatal 20d) for pancreatic maturation for RNA extraction and hybridization on Affymetrix microarrays. We obtained immature and mature beta cell-enriched populations from postnatal 20d and 2 months animals in order to compare their expression profiles. To that end, we used primary cultured FACS-enriched beta cell populations according to their FSC, SSC and autoflourescence. We used three replicates for each condition.