| 1. |
- Tattikota, Sudhir G., et al.
(författare)
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miR-184 Regulates Pancreatic beta-Cell Function According to Glucose Metabolism
- 2015
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 290:33, s. 20284-20294
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Tidskriftsartikel (refereegranskat)abstract
- In response to fasting or hyperglycemia, the pancreatic beta-cell alters its output of secreted insulin; however, the pathways governing this adaptive response are not entirely established. Although the precise role of microRNAs (miRNAs) is also unclear, a recurring theme emphasizes their function in cellular stress responses. We recently showed that miR-184, an abundant miRNA in the beta-cell, regulates compensatory proliferation and secretion during insulin resistance. Consistent with previous studies showing miR-184 suppresses insulin release, expression of this miRNA was increased in islets after fasting, demonstrating an active role in the beta-cell as glucose levels lower and the insulin demand ceases. Additionally, miR-184 was negatively regulated upon the administration of a sucrose-rich diet in Drosophila, demonstrating strong conservation of this pathway through evolution. Furthermore, miR-184 and its target Argonaute2 remained inversely correlated as concentrations of extracellular glucose increased, underlining a functional relationship between this miRNA and its targets. Lastly, restoration of Argonaute2 in the presence of miR-184 rescued suppression of miR-375-targeted genes, suggesting these genes act in a coordinated manner during changes in the metabolic context. Together, these results highlight the adaptive role of miR-184 according to glucose metabolism and suggest the regulatory role of this miRNA in energy homeostasis is highly conserved.
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| 2. |
- Tattikota, Sudhir G, et al.
(författare)
-
Argonaute2 Mediates Compensatory Expansion of the Pancreatic β Cell.
- 2014
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 19:1, s. 122-134
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic β cells adapt to compensate for increased metabolic demand during insulin resistance. Although the microRNA pathway has an essential role in β cell proliferation, the extent of its contribution is unclear. Here, we report that miR-184 is silenced in the pancreatic islets of insulin-resistant mouse models and type 2 diabetic human subjects. Reduction of miR-184 promotes the expression of its target Argonaute2 (Ago2), a component of the microRNA-induced silencing complex. Moreover, restoration of miR-184 in leptin-deficient ob/ob mice decreased Ago2 and prevented compensatory β cell expansion. Loss of Ago2 during insulin resistance blocked β cell growth and relieved the regulation of miR-375-targeted genes, including the growth suppressor Cadm1. Lastly, administration of a ketogenic diet to ob/ob mice rescued insulin sensitivity and miR-184 expression and restored Ago2 and β cell mass. This study identifies the targeting of Ago2 by miR-184 as an essential component of the compensatory response to regulate proliferation according to insulin sensitivity.
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| 3. |
- Tattikota, Sudhir G, et al.
(författare)
-
MiR-184 regulates pancreatic β-cell function according to glucose metabolism.
- 2015
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 290:33, s. 20284-20294
-
Tidskriftsartikel (refereegranskat)abstract
- In response to fasting or hyperglycemia, the pancreatic β-cell alters its output of secreted insulin; however the pathways governing this adaptive response are not entirely established. While the precise role of microRNAs (miRNAs) is also unclear, a recurring theme emphasizes their function in cellular stress responses. We recently showed that miR-184, an abundant miRNA in the β-cell, regulates compensatory proliferation and secretion during insulin resistance. Consistent with previous studies showing miR-184 suppresses insulin release, expression of this miRNA was increased in islets after fasting, demonstrating an active role in the β-cell as glucose levels lower and the insulin demand ceases. Additionally, miR-184 was negatively regulated upon administration of a sucrose-rich diet in Drosophila demonstrating strong conservation of this pathway through evolution. Furthermore, miR-184 and its target Argonaute2 (Ago2) remained inversely correlated as concentrations of extracellular glucose increased, underlining a functional relationship between this miRNA and its targets. Lastly, restoration of Ago2 in the presence of miR-184 rescued suppression of miR-375-targeted genes suggesting these genes act in a coordinated manner during changes in the metabolic context. Together, these results highlight the adaptive role of miR-184 according to glucose metabolism and suggest the regulatory role of this miRNA in energy homeostasis is highly conserved.
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| 4. |
- Yan, Xin, et al.
(författare)
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Differential Impact of Glucose Administered Intravenously and Orally on Circulating miR-375 Levels in Human Subjects
- 2017
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 102:10, s. 3749-3755
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundTo date, numerous nucleic acid species have been detected in the systemic circulation including microRNAs (miRNAs); however, their functional role in this compartment remains unclear.ObjectiveThe aim of this study was to determine whether systemic levels of miRNAs abundant in blood, including the neuroendocrine tissue-enriched miR-375, are altered in response to a glucose challenge.DesignTwelve healthy males were recruited for an acute crossover study that consisted of two tests each following an 8-hour fasting period. An oral glucose tolerance test (OGTT) was performed, and blood samples were collected over a 3-hour period. Following a period of at least 1 week, the same participants were administered an isoglycemic intravenous glucose infusion (IIGI) with the same blood-collection protocol.ResultsThe glucose response curve following the IIGI mimicked that obtained after the OGTT, but as expected, systemic insulin levels were lower during the IIGI compared with the OGTT (P < 0.05). miR-375 levels in circulation were increased only in response to an OGTT and not during an IIGI. In addition, the response to the OGTT also coincided with the transient increase of circulating glucagon-like peptide (GLP)-1, GLP-2, and glucose-dependent insulinotropic polypeptide.ConclusionsThe present findings show levels of miR-375 increase following administration of an OGTT and, in light of its enrichment in cells of the gut, suggest that the gastrointestinal tract may play an important role in the abundance and function of this miRNA in the blood.
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