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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

Functional characterization of miR-375KO mice with selective re-expression of miR-375 in pancreatic β-cells. a Relative miR-375 expression in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). Data expressed as fold-change over WT controls. b Relative expression of the miR-375 target HuD in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). c Detection of miR-375 and 28S rRNA in pancreatic tissue sections from wildtype (WT), miR-375KO, and β-Rescue mice using miRNA FISH. Green: miR-375, Red: 28S rRNA, Blue: cell nuclei. All data shown are mean ± s.e.m. *p < 0.05, ***p < 0.005
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Fig2: Functional characterization of miR-375KO mice with selective re-expression of miR-375 in pancreatic β-cells. a Relative miR-375 expression in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). Data expressed as fold-change over WT controls. b Relative expression of the miR-375 target HuD in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). c Detection of miR-375 and 28S rRNA in pancreatic tissue sections from wildtype (WT), miR-375KO, and β-Rescue mice using miRNA FISH. Green: miR-375, Red: 28S rRNA, Blue: cell nuclei. All data shown are mean ± s.e.m. *p < 0.05, ***p < 0.005

Mentions: To investigate the specific role of miR-375 in pancreatic β-cells for the metabolic impairment in the global miR-375KO mice, we crossed Tg375 mice with miR-375KO animals in order to re-constitute miR-375 expression selectively in β-cells, while leaving other islet endocrine cells and organs depleted of the miRNA (Tg375/mir-375KO mice are referred to as “β-Rescue” mice). Quantitative PCR (qPCR) indicated that expression of miR-375 was recovered to ≈85 % of wildtype (WT) in β-Rescue islets (Fig. 2a). To further validate the selective reconstitution of miR-375 levels in β-Rescue mice, we measured mRNA levels of HuD, encoding an RNA-binding protein that regulates translation of the insulin2 mRNA [21] and an evolutionarily conserved and experimentally validated miR-375 target in β-cells [10]. This analysis revealed that HuD is upregulated ≈3-fold in miR-375KO islets but downregulated in β-Rescue mice to similar levels than WT animals (Fig. 2b). Finally, in situ hybridization with miR-375 probes confirmed restoration of miR-375 expression in the core of pancreatic islets of β-Rescue mice (Fig. 2c). Together, these results show that the Tg375 transgene could selectively and functionally restore endogenous miR-375 expression in β-cells of miR-375KO mice.Fig. 2


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)

Functional characterization of miR-375KO mice with selective re-expression of miR-375 in pancreatic β-cells. a Relative miR-375 expression in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). Data expressed as fold-change over WT controls. b Relative expression of the miR-375 target HuD in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). c Detection of miR-375 and 28S rRNA in pancreatic tissue sections from wildtype (WT), miR-375KO, and β-Rescue mice using miRNA FISH. Green: miR-375, Red: 28S rRNA, Blue: cell nuclei. All data shown are mean ± s.e.m. *p < 0.05, ***p < 0.005
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4589563&req=5

Fig2: Functional characterization of miR-375KO mice with selective re-expression of miR-375 in pancreatic β-cells. a Relative miR-375 expression in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). Data expressed as fold-change over WT controls. b Relative expression of the miR-375 target HuD in islets of male WT, Tg375, miR-375KO, and β-Rescue mice at 12 weeks of age (n = 4–5). c Detection of miR-375 and 28S rRNA in pancreatic tissue sections from wildtype (WT), miR-375KO, and β-Rescue mice using miRNA FISH. Green: miR-375, Red: 28S rRNA, Blue: cell nuclei. All data shown are mean ± s.e.m. *p < 0.05, ***p < 0.005
Mentions: To investigate the specific role of miR-375 in pancreatic β-cells for the metabolic impairment in the global miR-375KO mice, we crossed Tg375 mice with miR-375KO animals in order to re-constitute miR-375 expression selectively in β-cells, while leaving other islet endocrine cells and organs depleted of the miRNA (Tg375/mir-375KO mice are referred to as “β-Rescue” mice). Quantitative PCR (qPCR) indicated that expression of miR-375 was recovered to ≈85 % of wildtype (WT) in β-Rescue islets (Fig. 2a). To further validate the selective reconstitution of miR-375 levels in β-Rescue mice, we measured mRNA levels of HuD, encoding an RNA-binding protein that regulates translation of the insulin2 mRNA [21] and an evolutionarily conserved and experimentally validated miR-375 target in β-cells [10]. This analysis revealed that HuD is upregulated ≈3-fold in miR-375KO islets but downregulated in β-Rescue mice to similar levels than WT animals (Fig. 2b). Finally, in situ hybridization with miR-375 probes confirmed restoration of miR-375 expression in the core of pancreatic islets of β-Rescue mice (Fig. 2c). Together, these results show that the Tg375 transgene could selectively and functionally restore endogenous miR-375 expression in β-cells of miR-375KO mice.Fig. 2

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