Expression profiles of microRNAs from lactating and non-lactating bovine mammary glands
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ABSTRACT: miRNAs have been implicated in the regulation of milk protein synthesis and development of mammary gland. However, the function of miRNAs in regulating lactation is unclear. Therefore, the elucidation of miRNA expression profiles in MG provides a crucial entry into the understanding of the mechanisms of lactation initiation. Our present work is to examine miRNA expression profiles in bovine mammary gland, and to evaluate miRNAs function through the identification of differentially expressed miRNA between lactation and non-lactation mammary gland. Identification of novel miRNAs highlights the important function of low abundance and less conserved miRNAs. An interaction network of known miRNAs and their target genes around the lactation function was constructed to postulate the functional roles of miRNAs in mammary gland. This integrated analysis provides important information that will inspire further experimental investigations into the field of miRNAs and their targets during lactation. Examination of 2 different miRNA expression profilings in bovine mammary gland
Project description:miRNAs have been implicated in the regulation of milk protein synthesis and development of mammary gland. However, the function of miRNAs in regulating lactation is unclear. Therefore, the elucidation of miRNA expression profiles in MG provides a crucial entry into the understanding of the mechanisms of lactation initiation. Our present work is to examine miRNA expression profiles in bovine mammary gland, and to evaluate miRNAs function through the identification of differentially expressed miRNA between lactation and non-lactation mammary gland. Identification of novel miRNAs highlights the important function of low abundance and less conserved miRNAs. An interaction network of known miRNAs and their target genes around the lactation function was constructed to postulate the functional roles of miRNAs in mammary gland. This integrated analysis provides important information that will inspire further experimental investigations into the field of miRNAs and their targets during lactation.
Project description:Background: The mammary gland is a dynamic organ that undergoes important physiological changes during reproductive cycles. Until now, data regarding the characterisation of miRNA in the mammary gland have been scarce and mainly focused on their abnormal expression in breast cancer. Our goal was to characterise the microRNA (miRNA) involved in mechanisms regulating the mammary function, with particular focus on the lactation stage Methodology/principal findings: Using high-throughput sequencing technology, an exhaustive repertoire of miRNA (miRNome) expressed in mouse and bovine mammary glands during established lactation was identified, characterised and compared. Furthermore, in order to obtain more information on miRNA loading in the RNA-induced silencing complex (RISC), the miRNome was compared with that obtained from RNA associated with the AGO2 protein (AGO2-miRNome) in mouse lactating mammary gland. This study enabled the identification of 164 and 167 miRNA in mouse and bovine, respectively. Among the 30 miRNA most highly expressed in each species, 24 were common to both species and six of them tended to be more highly expressed in lactating than in non-lactating mammary gland. The potential functional roles of these 24 miRNA were deduced using DIANA-miRPath software, based on miRNA/mRNA interactions. Moreover, seven putative novel miRNA were identified. Using DAVID analysis, it was concluded that the predicted targets of two of these putative novel miRNA are involved in mammary gland morphogenesis. Conclusion/significance: Our study provides an overview of the characteristics of lactating mouse and bovine mammary gland miRNA expression profiles. Moreover, species-conserved miRNA involved in this fundamental biological function were identified. These miRNomes will new be used as references for further studies during which the impact of animal breeding on the miRNA expression will be analysed. microRNA profiles of mammary glands from 2 FVB/N mice at lactation day-12 and mammary biopsies from 4 Holstein dairy cows at mid-lactation, generated by deep sequencing, using Illumina HiSeq 2000.
Project description:Background: The mammary gland is a dynamic organ that undergoes important physiological changes during reproductive cycles. Until now, data regarding the characterisation of miRNA in the mammary gland have been scarce and mainly focused on their abnormal expression in breast cancer. Our goal was to characterise the microRNA (miRNA) involved in mechanisms regulating the mammary function, with particular focus on the lactation stage Methodology/principal findings: Using high-throughput sequencing technology, an exhaustive repertoire of miRNA (miRNome) expressed in mouse and bovine mammary glands during established lactation was identified, characterised and compared. Furthermore, in order to obtain more information on miRNA loading in the RNA-induced silencing complex (RISC), the miRNome was compared with that obtained from RNA associated with the AGO2 protein (AGO2-miRNome) in mouse lactating mammary gland. This study enabled the identification of 164 and 167 miRNA in mouse and bovine, respectively. Among the 30 miRNA most highly expressed in each species, 24 were common to both species and six of them tended to be more highly expressed in lactating than in non-lactating mammary gland. The potential functional roles of these 24 miRNA were deduced using DIANA-miRPath software, based on miRNA/mRNA interactions. Moreover, seven putative novel miRNA were identified. Using DAVID analysis, it was concluded that the predicted targets of two of these putative novel miRNA are involved in mammary gland morphogenesis. Conclusion/significance: Our study provides an overview of the characteristics of lactating mouse and bovine mammary gland miRNA expression profiles. Moreover, species-conserved miRNA involved in this fundamental biological function were identified. These miRNomes will new be used as references for further studies during which the impact of animal breeding on the miRNA expression will be analysed.
Project description:In this study, two small RNA libraries were constructed using dry period and peak lactation dairy goat mammary gland tissues and sequenced by the Illumina Solexa high-throughput sequencing system. A total of 346 conserved and 95 novel miRNAs were identified in the dairy goat. The expression of miRNAs was confirmed by qRT-PCR in nine tissues and the mammary gland during development cycles. In addition, several candidate miRNAs that may be involved in mammary gland development and lactation were found by the comparison of miRNA expression profiles among different tissue and developmental stages of the mammary gland. This study provides the identification and profile of miRNAs related to the biology of the mammary gland in the dairy goat. The identification of these miRNAs could contribute to understanding the molecular mechanisms of lactation physiology and the development of the mammary gland in the dairy goat.
Project description:Growth hormone (GH) has a well established galactopoietic effect on ruminant lactation, however the molecular mechanisms that mediate these effects are not fully understood. This study aimed to define the effects of GH on the production of milk protein by the bovine mammary gland and to establish the potential molecular mechanisms mediating these effects. Elevated levels of GH increased milk yield with corresponding increases in protein, fat and lactose yield, while milk composition remained unaffected by treatment. Increased yield (but not concentration) of all the individual milk proteins was not accompanied by changes in the levels of the milk protein transcripts, with the exception of S2-casein, suggesting post-transcriptional regulation of the milk protein genes is a main factor in the GH-mediated effects on bovine lactation. There were significant transcriptional changes in a wide range of pathways including cell signaling, cell death, cell growth and proliferation, cell cycle regulation and metabolism, consistent with the broad effects of GH. Differential expression of genes involved in the PI3K, ERK/MAPK, insulin receptor, JAK/STAT and IGF-1 signaling pathways were also evident in response to GH treatment supporting potential cross-talk between the GH and insulin signaling pathways in the bovine mammary gland. Transcript levels of the SHC1 gene were elevated in GH-treated cows. SHC1 activates many pathways including those associated with translational regulation and gene transcription and has been implicated in mediating cross-talk between the insulin and GH signaling pathways, providing some insights into the potential pathways mediating the effects of GH on milk protein synthesis in the bovine mammary gland.
Project description:Previoulsly miRNA expression profiling of the whole mammary gland across different stages of pregnancy and lactation has been performed in mice. Since mammary gland has both epithelial and stromal compartments, to specifically identify the miRNAs involved in the transition from pregnancy to lactation a process termed as secretory activation, expression profiling of isolated mammary epithelial cells (MECs) from four CD1 mice each at Pregnancy day 14 (P14) and Lactation day 2 (L2) was performed in the current study. Statistical analysis of the miRNA changes between P14 and L2 identified 32 miRNAs to be differentially expressed with a fold change greater than or equal to 2, of which, the majority of them declinied at the onset of lactation.
Project description:High throughput sequencing of miRNAs collected from tammar milk at different time points of lactation showed high levels of miRNA secreted in milk and allowed the identification of differentially expressed milk miRNAs during the lactation cycle as putative markers of mammary gland activity and functional candidate signals to assist growth and timed development of the young. Comparative analysis of miRNA distribution in milk and blood serum suggests that milk miRNAs are primarily expressed from mammary gland rather than transferred from maternal circulating blood, likely through a new putative exosomal secretory pathway.
Project description:A series of experiments to establish a bovine developing mammary gland gene expression signature, identify genes differentially expressed in bovine lactating mammary gland, and to establish the false positive rate of the BMAM microarray Keywords = gene expression, differential expression, lactation, development, physiology, bovine, mammary, microarray, EST, cDNA Keywords: repeat sample
Project description:Background: The differential expression pattern of microRNAs (miRNAs) during mammary gland development might provide insights into their role in regulating the homeostasis of the breast epithelium. Our aim was to analyse these regulatory functions by deriving a comprehensive tissue-specific combined miRNA and mRNA expression profile of post-natal mouse mammary gland development. We measured the expression of 318 individual murine miRNAs by bead-based flow-cytometric profiling of whole mouse mammary glands throughout a 16-point developmental time course, including juvenile, puberty, mature virgin, gestation, lactation, and involution stages. In parallel whole-genome mRNA expression data were obtained. Results: One third (n = 102) of all murine miRNAs analysed were present during mammary gland development. MicroRNAs were represented in seven temporally co-expressed clusters, which were enriched for both miRNAs belonging to the same family and breast cancer-associated miRNAs. Global miRNA and mRNA expression was significantly reduced during lactation and the early stages of involution after weaning. For most detected miRNA families we did not observe systematic changes in the expression of predicted targets. For miRNA families whose targets did show significant changes, we observed inverse patterns of miRNA and target expression. The datasets are made publicly available and the combined expression profiles represent an important community resource for mammary gland biology research. Conclusions: MicroRNAs were expressed in co-regulated clusters during mammary gland development. Breast cancer-associated miRNAs were significantly enriched in these clusters. The mechanism and functional consequences of this miRNA co-regulation and its correlation with mRNA expression provide new avenues for research into mammary gland biology and generates candidates for functional validation. This SuperSeries is composed of the following subset Series: GSE15054: Characterisation of microRNA expression in post-natal mouse mammary gland development [gene] GSE15055: Characterisation of microRNA expression in post-natal mouse mammary gland development [miRNA] Refer to individual Series
Project description:High throughput sequencing of miRNAs collected from tammar milk at different time points of lactation showed high levels of miRNA secreted in milk and allowed the identification of differentially expressed milk miRNAs during the lactation cycle as putative markers of mammary gland activity and functional candidate signals to assist growth and timed development of the young. Comparative analysis of miRNA distribution in milk and blood serum suggests that milk miRNAs are primarily expressed from mammary gland rather than transferred from maternal circulating blood, likely through a new putative exosomal secretory pathway. 8 profiles were produced. Duplicates of day175