| 1. |
- Tattikota, Sudhir G, et al.
(författare)
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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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| 2. |
- Tattikota, Sudhir G., et al.
(författare)
-
miR-184 Regulates Pancreatic beta-Cell Function According to Glucose Metabolism
- 2015
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 290:33, s. 20284-20294
-
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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| 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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