Expression and Localization of microRNAs in Perinatal Rat Pancreas: Role of miR-21 in Regulation of Cholesterol Metabolism

Louise Larsen,Louise T Dalgaard,Christina M Dahmcke,Jens H Nielsen,Annika Bagge,Maiken W Rosenstierne,Louise W Gaarn,Lykke Pedersen

doi:10.1371/journal.pone.0025997

Louise Larsen, Louise T Dalgaard + Show 6 more

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https://doi.org/10.1371/journal.pone.0025997

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Journal: PloS one	Publication Date: Oct 11, 2011
Citations: 66	License type: CC BY 4.0

Affiliation: University of Copenhagen, Roskilde University

Abstract

ObjectiveTo investigate the expression of pancreatic microRNAs (miRNAs) during the period of perinatal beta-cell expansion and maturation in rats, determine the localization of these miRNAs and perform a pathway analysis with predicted target mRNAs expressed in perinatal pancreas.Research Design and MethodsRNA was extracted from whole pancreas at embryonic day 20 (E20), on the day of birth (P0) and two days after birth (P2) and hybridized to miRNA microarrays. Differentially expressed miRNAs were verified by northern blotting and their pancreatic localization determined by in situ hybridization. Pathway analysis was done using regulated sets of mRNAs predicted as targets of the miRNAs. Possible target genes were tested using reporter-gene analysis in INS-1E cells.ResultsNine miRNAs were differentially expressed perinatally, seven were confirmed to be regulated at the level of the mature miRNA. The localization studies showed endocrine localization of six of these miRNAs (miR-21, -23a, -29a, -125b-5p, -376b-3p and -451), and all were expressed in exocrine cells at one time point at least. Pathways involving metabolic processes, terpenoid and sterol metabolism were selectively affected by concomitant regulation by miRNAs and mRNAs, and Srebf1 was validated as a target of miR-21.ConclusionsThe findings suggest that miRNAs are involved in the functional maturation of pancreatic exocrine and endocrine tissue following birth. Pathway analysis of target genes identify changes in sterol metabolism around birth as being selectively affected by differential miRNA expression during this period.

Highlights

MicroRNAs are small, single-stranded non-coding RNA molecules involved in post-transcriptional control of geneexpression of a wide number of genes
Terpenoid and sterol metabolism were selectively affected by concomitant regulation by miRNAs and mRNAs, and Srebf1 was validated as a target of miR-21
The findings suggest that miRNAs are involved in the functional maturation of pancreatic exocrine and endocrine tissue following birth

Summary

Introduction

MicroRNAs (miRNAs) are small, single-stranded non-coding RNA molecules involved in post-transcriptional control of geneexpression of a wide number of genes. MiRNAs have been found to regulate many animal developmental events such as proliferation, differentiation and apoptosis [4]. Development of pancreas and islets of Langerhans is highly dependent on developmental timing controlling specification, neogenesis, proliferation and differentiation of individual cell types [5]. Removal of endogenous miRNAs at different embryonic time-points using Dicer(flox/flox) mice illustrate that miRNAs are involved in the fetal development of pancreas, most notably the beta-cell lineage [6]. MiR-375 is one of few miRNAs (along with miR-7) expressed mainly in adult islets and only marginally elsewhere [10,11,12,13], and controls a cluster of genes regulating cellular growth and proliferation, evident from studies of miR-375(2/2) mice, which are hyperglycemic and have decreased beta-cell mass [11]. MiRNAs have important functions in mature beta-cells and for fetal development of beta-cells

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