MicroRNA-124a regulates Foxa2 expression and intracellular signaling in pancreatic beta-cell lines.
MicroRNAs (miRNAs) are short non-coding RNAs that have been implicated in fine-tuning gene regulation, although the precise roles of many are still unknown. Pancreatic development is characterized by the complex sequential expression of a gamut of transcription factors. We have performed miRNA expression profiling at two key stages of mouse embryonic pancreas development, e14.5 and e18.5. miR-124a2 expression was strikingly increased at e18.5 compared with e14.5, suggesting a possible role in differentiated beta-cells. Among the potential miR-124a gene targets identified by biocomputation, Foxa2 is known to play a role in beta-cell differentiation. To evaluate the impact of miR-124a2 on gene expression, we overexpressed or down-regulated miR-124a2 in MIN6 beta-cells. As predicted, miR-124a2 regulated Foxa2 gene expression, and that of its downstream target, pancreatic duodenum homeobox-1 (Pdx-1). Foxa2 has been described as a master regulator of pancreatic development and also of genes involved in glucose metabolism and insulin secretion, including the ATP-sensitive K(+) (K(ATP)) channel subunits, Kir6.2 and Sur-1. Correspondingly, miR-124a2 overexpression decreased, and anti-miR-124a2 increased Kir6.2 and Sur-1 mRNA levels. Moreover, miR-124a2 modified basal and glucose- or KCl-stimulated intracellular free Ca(2+) concentrations in single MIN6 and INS-1 (832/13) beta-cells, without affecting the secretion of insulin or co-transfected human growth hormone, consistent with an altered sensitivity of the beta-cell exocytotic machinery to Ca(2+). In conclusion, whereas the precise role of microRNA-124a2 in pancreatic development remains to be deciphered, we identify it as a regulator of a key transcriptional protein network in beta-cells responsible for modulating intracellular signaling.
Baroukh
Nadine
N
INSERM, U145, Nice, F-06107, France.
Ravier
Magalie A
MA
Loder
Merewyn K
MK
Hill
Elaine V
EV
Bounacer
Ali
A
Scharfmann
Raphaël
R
Rutter
Guy A
GA
Van Obberghen
Emmanuel
E
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism; D051542:Hepatocyte Nuclear Factor 3-beta / Q000096:biosynthesis* / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D038081:Organogenesis / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D000099161:Kcnj11 Channel
D002118:Calcium; D005947:Glucose; D013006:Growth Hormone; D051542:Hepatocyte Nuclear Factor 3-beta; D018398:Homeodomain Proteins; D007328:Insulin; D035683:MicroRNAs; D024661:Potassium Channels, Inwardly Rectifying; D015534:Trans-Activators; D000099161:Kcnj11 Channel; C496503:Foxa2 protein, mouse; C084010:pancreatic and duodenal homeobox 1 protein