Unknown,Transcriptomics,Genomics,Proteomics

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Profiling microRNA expression in bovine alveolar macrophages using RNA-seq

ABSTRACT: In this study, we determined the miRNA expression profile of bovine alveolar macrophages, using next-generation sequencing strategy. On an Illumina HiSeq 2000 machine, we sequenced 8 miRNA libraries, prepared from small RNA fractions of alveolar macrophages isolated from 8 different healthy animals (Bos taurus). From the data, the potential novel miRNAs were predicted, and the expression levels of the known miRNAs were determined. We report that 80 known bovine miRNAs are expressed in bovine alveolar macrophages with >100 reads per million. The most highly expressed miRNA was bta-miR-21, followed by bta-miR-27a. Additionally, one putatively novel bovine miRNA was identified. To our knowledge, this is the first RNA-seq study to profile miRNA expression in bovine alveolar macrophages and provides an important reference dataset for investigating the regulatory roles miRNAs play in this important immune cell type. Examination of bovine alveolar macrophage miRNA profiles, using RNA-seq. Alveolar macrophages were isolated from lung lavages from 8 animals. Small RNA fractions were prepared from the cells using the Qiagen RNeasy Plus mini kit, and miRNA sequencing libraries were prepared using the Epicentre Scriptminer multiplex kit. The sequencing was performed on an Illumina HiSeq 2000 machine.

ORGANISM(S): Bos taurus

SUBMITTER: Peter Vegh

PROVIDER: E-GEOD-41138 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Purpose: The goal of this RNA-seq study was to profile changes in miRNA expression in bovine alveolar macrophages isolated from Holstein-Friesian and challenged with M. bovis over a 48 hour time course. Background: Mycobacterium bovis, the causative agent of bovine tuberculosis, is a major infectious disease problem for global agriculture, resulting in losses of billions of Euros annually. The bacterium spreads via an airborne route and is taken up by alveolar macrophages in the lung. MicroRNAs (miRNAs) — short non-coding RNAs that post-transcriptionally regulate gene expression — are increasingly being recognised as key regulators of the immune system. There is mounting evidence for the role of miRNAs in regulating the early innate immune response to mycobacterial infections; however, the underlying processes are not fully understood yet. Results: In total, 2.5 billion raw sequencing reads were generated. 93% of post-filtered reads aligned to known miRNAs. The expression of miRNAs varied over a wide range: miR-21 was expressed at approximately 430,000 reads per million (RPM), but the majority were more lowly expressed (1000-10,000 RPM). One, six, and 40 miRNAs were identified as significantly differentially expressed at 2, 24 and 48 h post-infection (hpi), respectively (FDR < 0.05); the differential expression at 48 hpi of three (out of four) of these miRNAs was confirmed by RT-qPCR. No miRNAs were detected to be differentially expressed 6 hpi. Many of the differentially expressed miRNAs have been shown to have a role in the host response to mycobacterial pathogens and other infections in other species. MicroRNA-155, for example, which we observed to be upregulated in response to M. bovis has recently been shown to control autophagy in murine macrophages infected with the human pathogen Mycobacterium tuberculosis. Pathway analysis suggests that upregulated miRNAs target endocytosis and lysosome trafficking, thus potentially enhancing bacterial survival. An independent gene silencing experiment with a bovine macrophage cell line (Bomac) has confirmed downregulation of IRAK1 by miR-146a and miR-146b. Moreover, downregulation of another predicted target, TGFRB2, by miR-146a was also confirmed. These findings support the target prediction and pathway analysis results. Our results suggest that several miRNAs have an important role in the alveolar macrophage response to pathogenic mycobacteria.

Project description:M cells in the follicle-associated epithelium (FAE) of Peyer’s patches (PPs) serve as a main portal for external antigens. Limitation in the number of M cells has hampered identification of their specific molecules until recently. Efforts by us as well as others has gradually unraveled the molecular mechanisms for the development and differentiation of M cells. However, molecular mechanisms of antigen transcytosis and M cell differentiation were not fully elucidated. Recent studies reported that small non-coding RNAs including microRNA (miRNA) regulate gene expression that controls various biological processes such as cellular differentiation and functions. In fact, intestinal epithelial miRNAs play a critical role in goblet cell differentiation and maturation. However, the expression and function of miRNAs in FAE including M cell that function as the sentinels in the mucosal immune system are largely unknown. To address this notion, we performed microarray analysis to characterize expression profiles of miRNA in intestinal villous epithelium (VE) and FAE of PP. We also generated mice with intestinal epithelial cell-specific deletion of Dicer1 (DicerΔIEC), in which intestinal phenotypes including M-cell differentiation and epithelial morphology were examined. The microarray analysis identified that 72 miRNAs were up-regulated whereas 11 miRNAs were down-regulated, in FAE compared to VE. DicerΔIEC mice displayed a prominent decrease in mature M cells, suggesting an essential role of miRNAs in maturation of the cell type. Furthermore, electron micrographs clearly showed that depletion of miRNA caused the loss of endosomal structures in M cells. In addition, antigen uptake in M cells was impaired in DicerΔIEC mice compared to control floxed Dicer mice. These results raised the possibility that miRNAs play a significant role in the regulation of M cells maturation, and consequently secure mucosal immune homeostasis. Follicle associated epithelium or villous epithelium was isolated from Peyer's patch(PP). PP was soaked Hank's balanced salt solution (HBSS;GIBCO) containing 30mM EDTA. After incubation at 4℃ for 20 min, FAE or VE was isolated by manipulation with fine needle under stereomicroscopic monitoring. The isolated epithelial cell sheets were kept in ice-cold HBSS until RNA extraction(n=2).

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Profiling microRNA expression in bovine alveolar macrophages using RNA-seq

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