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miR-375 gene dosage in pancreatic β-cells: implications for regulation of β-cell mass and biomarker development.

Latreille M, Herrmanns K, Renwick N, Tuschl T, Malecki MT, McCarthy MI, Owen KR, Rülicke T, Stoffel M - J. Mol. Med. (2015)

Bottom Line: Furthermore, acute and profound β-cell destruction is sufficient to detect elevations of miR-375 levels in the blood.Together, our data support an essential role for miR-375 in the maintenance of β-cell mass and provide in vivo evidence for release of miRNAs from pancreatic β-cells.Circulating miR-375 levels are not a biomarker for pancreatic β-cell function.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH Zurich), Otto-Stern Weg. 7, 8093, Zurich, Switzerland.

ABSTRACT

Unlabelled: MicroRNAs play a crucial role in the regulation of cell growth and differentiation. Mice with genetic deletion of miR-375 exhibit impaired glycemic control due to decreased β-cell and increased α-cell mass and function. The relative importance of these processes for the overall phenotype of miR-375KO mice is unknown. Here, we show that mice overexpressing miR-375 exhibit normal β-cell mass and function. Selective re-expression of miR-375 in β-cells of miR-375KO mice normalizes both, α- and β-cell phenotypes as well as glucose metabolism. Using this model, we also analyzed the contribution of β-cells to the total plasma miR-375 levels. Only a small proportion (≈1 %) of circulating miR-375 originates from β-cells. Furthermore, acute and profound β-cell destruction is sufficient to detect elevations of miR-375 levels in the blood. These findings are supported by higher miR-375 levels in the circulation of type 1 diabetes (T1D) subjects but not mature onset diabetes of the young (MODY) and type 2 diabetes (T2D) patients. Together, our data support an essential role for miR-375 in the maintenance of β-cell mass and provide in vivo evidence for release of miRNAs from pancreatic β-cells. The small contribution of β-cells to total plasma miR-375 levels make this miRNA an unlikely biomarker for β-cell function but suggests a utility for the detection of acute β-cell death for autoimmune diabetes.

Key messages: • Overexpression of miR-375 in β-cells does not influence β-cell mass and function. • Increased α-cell mass in miR-375KO arises secondarily to loss of miR-375 in β-cells. • Only a small proportion of circulating miR-375 levels originates from β-cells. • Acute β-cell destruction results in measurable increases of miR-375 in the blood. Circulating miR-375 levels are not a biomarker for pancreatic β-cell function.

No MeSH data available.


Related in: MedlinePlus

Metabolic characterization of β-cell-specific miR-375 transgenic mice. a Relative miR-375 expression in islets and indicated organs of male wildtype (WT) and Tg375 mice at 12 weeks of age (n = 5 for islets, n = 2 for all other tissues). b Relative expression of validated miR-375 targets in islets of male Tg375 mice and WT controls at 12 week of age. c Body weight of Tg375 (white circles) and WT (black circles) mice (n = 10). d Ad libitum-fed blood glucose levels in Tg375 and control littermate mice (n = 10). e Intraperitoneal Glucose Tolerance Test (IPGTT; 2 g/kg) in overnight fasted Tg375 (white circles) and WT (black circles) mice at 10 weeks of age (n = 11). f Static insulin secretion performed with 10-week-old control and Tg375 islets (n = 5) at 3.3 mmol/l (white bars) and 16.7 mmol/l (black bars) glucose concentrations. All data shown are mean ± s.e.m., except for panel c and d where s.d. is shown. *p < 0.05, **p < 0.01
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Fig1: Metabolic characterization of β-cell-specific miR-375 transgenic mice. a Relative miR-375 expression in islets and indicated organs of male wildtype (WT) and Tg375 mice at 12 weeks of age (n = 5 for islets, n = 2 for all other tissues). b Relative expression of validated miR-375 targets in islets of male Tg375 mice and WT controls at 12 week of age. c Body weight of Tg375 (white circles) and WT (black circles) mice (n = 10). d Ad libitum-fed blood glucose levels in Tg375 and control littermate mice (n = 10). e Intraperitoneal Glucose Tolerance Test (IPGTT; 2 g/kg) in overnight fasted Tg375 (white circles) and WT (black circles) mice at 10 weeks of age (n = 11). f Static insulin secretion performed with 10-week-old control and Tg375 islets (n = 5) at 3.3 mmol/l (white bars) and 16.7 mmol/l (black bars) glucose concentrations. All data shown are mean ± s.e.m., except for panel c and d where s.d. is shown. *p < 0.05, **p < 0.01

Mentions: To further characterize the β-cell growth promoting activity of miR-375, we generated transgenic miR-375 mice in which the pre-miR-375 was cloned downstream of the insulin promoter (referred to as Tg375). Two founder lines were derived from pronuclei microinjections, and both lines displayed ≈2-fold overexpression of miR-375 in pancreatic islets, without “leakage” in other organs such lung, spleen, muscle, colon, kidney, or heart, except minor escape in the brain, consistent with leakage of the insulin promoter in selected hypothalamic neurons (Fig. 1a). We confirmed that expression of validated mRNA targets of miR-375 such as Gphn, Chsys, Insig2, Mtpn, and Eef1e1 were downregulated in Tg375 islets (Fig. 1b) [10]. Surprisingly, metabolic characterization of Tg375 did not reveal significant changes in weight, blood glucose, glucose tolerance, or pancreatic endocrine function as compared to control littermate mice (Figs. 1c–f, 3, and 4). These results indicate that increased miR-375 gene dosage in pancreatic β-cells of mice does not alter pancreatic endocrine cell composition and glucose tolerance.Fig. 1


miR-375 gene dosage in pancreatic β-cells: implications for regulation of β-cell mass and biomarker development.

Latreille M, Herrmanns K, Renwick N, Tuschl T, Malecki MT, McCarthy MI, Owen KR, Rülicke T, Stoffel M - J. Mol. Med. (2015)

Metabolic characterization of β-cell-specific miR-375 transgenic mice. a Relative miR-375 expression in islets and indicated organs of male wildtype (WT) and Tg375 mice at 12 weeks of age (n = 5 for islets, n = 2 for all other tissues). b Relative expression of validated miR-375 targets in islets of male Tg375 mice and WT controls at 12 week of age. c Body weight of Tg375 (white circles) and WT (black circles) mice (n = 10). d Ad libitum-fed blood glucose levels in Tg375 and control littermate mice (n = 10). e Intraperitoneal Glucose Tolerance Test (IPGTT; 2 g/kg) in overnight fasted Tg375 (white circles) and WT (black circles) mice at 10 weeks of age (n = 11). f Static insulin secretion performed with 10-week-old control and Tg375 islets (n = 5) at 3.3 mmol/l (white bars) and 16.7 mmol/l (black bars) glucose concentrations. All data shown are mean ± s.e.m., except for panel c and d where s.d. is shown. *p < 0.05, **p < 0.01
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig1: Metabolic characterization of β-cell-specific miR-375 transgenic mice. a Relative miR-375 expression in islets and indicated organs of male wildtype (WT) and Tg375 mice at 12 weeks of age (n = 5 for islets, n = 2 for all other tissues). b Relative expression of validated miR-375 targets in islets of male Tg375 mice and WT controls at 12 week of age. c Body weight of Tg375 (white circles) and WT (black circles) mice (n = 10). d Ad libitum-fed blood glucose levels in Tg375 and control littermate mice (n = 10). e Intraperitoneal Glucose Tolerance Test (IPGTT; 2 g/kg) in overnight fasted Tg375 (white circles) and WT (black circles) mice at 10 weeks of age (n = 11). f Static insulin secretion performed with 10-week-old control and Tg375 islets (n = 5) at 3.3 mmol/l (white bars) and 16.7 mmol/l (black bars) glucose concentrations. All data shown are mean ± s.e.m., except for panel c and d where s.d. is shown. *p < 0.05, **p < 0.01
Mentions: To further characterize the β-cell growth promoting activity of miR-375, we generated transgenic miR-375 mice in which the pre-miR-375 was cloned downstream of the insulin promoter (referred to as Tg375). Two founder lines were derived from pronuclei microinjections, and both lines displayed ≈2-fold overexpression of miR-375 in pancreatic islets, without “leakage” in other organs such lung, spleen, muscle, colon, kidney, or heart, except minor escape in the brain, consistent with leakage of the insulin promoter in selected hypothalamic neurons (Fig. 1a). We confirmed that expression of validated mRNA targets of miR-375 such as Gphn, Chsys, Insig2, Mtpn, and Eef1e1 were downregulated in Tg375 islets (Fig. 1b) [10]. Surprisingly, metabolic characterization of Tg375 did not reveal significant changes in weight, blood glucose, glucose tolerance, or pancreatic endocrine function as compared to control littermate mice (Figs. 1c–f, 3, and 4). These results indicate that increased miR-375 gene dosage in pancreatic β-cells of mice does not alter pancreatic endocrine cell composition and glucose tolerance.Fig. 1

Bottom Line: Furthermore, acute and profound β-cell destruction is sufficient to detect elevations of miR-375 levels in the blood.Together, our data support an essential role for miR-375 in the maintenance of β-cell mass and provide in vivo evidence for release of miRNAs from pancreatic β-cells.Circulating miR-375 levels are not a biomarker for pancreatic β-cell function.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH Zurich), Otto-Stern Weg. 7, 8093, Zurich, Switzerland.

ABSTRACT

Unlabelled: MicroRNAs play a crucial role in the regulation of cell growth and differentiation. Mice with genetic deletion of miR-375 exhibit impaired glycemic control due to decreased β-cell and increased α-cell mass and function. The relative importance of these processes for the overall phenotype of miR-375KO mice is unknown. Here, we show that mice overexpressing miR-375 exhibit normal β-cell mass and function. Selective re-expression of miR-375 in β-cells of miR-375KO mice normalizes both, α- and β-cell phenotypes as well as glucose metabolism. Using this model, we also analyzed the contribution of β-cells to the total plasma miR-375 levels. Only a small proportion (≈1 %) of circulating miR-375 originates from β-cells. Furthermore, acute and profound β-cell destruction is sufficient to detect elevations of miR-375 levels in the blood. These findings are supported by higher miR-375 levels in the circulation of type 1 diabetes (T1D) subjects but not mature onset diabetes of the young (MODY) and type 2 diabetes (T2D) patients. Together, our data support an essential role for miR-375 in the maintenance of β-cell mass and provide in vivo evidence for release of miRNAs from pancreatic β-cells. The small contribution of β-cells to total plasma miR-375 levels make this miRNA an unlikely biomarker for β-cell function but suggests a utility for the detection of acute β-cell death for autoimmune diabetes.

Key messages: • Overexpression of miR-375 in β-cells does not influence β-cell mass and function. • Increased α-cell mass in miR-375KO arises secondarily to loss of miR-375 in β-cells. • Only a small proportion of circulating miR-375 levels originates from β-cells. • Acute β-cell destruction results in measurable increases of miR-375 in the blood. Circulating miR-375 levels are not a biomarker for pancreatic β-cell function.

No MeSH data available.


Related in: MedlinePlus