Sorted stem/progenitor epithelial cells of pubertal bovine mammary gland present limited potential to reconstitute an organised mammary epithelium after transplantation.

The development and maintenance of mammary gland tissue depend on the proliferation and differentiation of mammary stem and progenitor cells. Here, we investigated populations of mammary epithelial cells that are potential candidates for bovine mammary gland development using xenotransplantation into mice cleared mammary fat pad. Transplanted mammary explants from 17-month-old Holstein heifers developed outgrowths exhibiting the archetypal morphology and molecular marker distributions of the bovine gland.

Mutation of SOCS2 induces structural and functional changes in mammary development.

Lactation is an essential process for mammals. In sheep, the R96C mutation in suppressor of cytokine signaling 2 (SOCS2) protein is associated with greater milk production and increased mastitis sensitivity. To shed light on the involvement of R96C mutation in mammary gland development and lactation, we developed a mouse model carrying this mutation (SOCS2KI/KI).

In silico identification of variations in microRNAs with a potential impact on dairy traits using whole ruminant genome SNP datasets.

MicroRNAs are small noncoding RNAs that have important roles in the lactation process and milk biosynthesis. Some polymorphisms have been studied in various livestock species from the perspective of pathology or production traits. To target variants that could be the causal variants of dairy traits, genetic variants of microRNAs expressed in the mammary gland or present in milk and localized in dairy quantitative trait loci (QTLs) were investigated in bovine, caprine, and ovine species.

Effect of feed restriction on dairy cow milk production: a review.

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes.

Epigenetics: New Insights into Mammary Gland Biology.

The mammary gland undergoes important anatomical and physiological changes from embryogenesis through puberty, pregnancy, lactation and involution. These steps are under the control of a complex network of molecular factors, in which epigenetic mechanisms play a role that is increasingly well described. Recently, studies investigating epigenetic modifications and their impacts on gene expression in the mammary gland have been performed at different physiological stages and in different mammary cell types.

Genomic DNA PCR analysis to assess xenograft development in mouse mammary gland.

The mouse transplantation model remains the most relevant methodology to assess the functional capacities of mammary cells and is particularly appropriate for investigations regarding mammary stem cells, whatever the species studied. Following xenotransplantation in mice mammary fat pad, the development of the xenograft is commonly evaluated by immunohistology. Here, we present a simple and rapid method to control the species specificity of a xenograft based on genomic DNA PCR amplification.

RumimiR: a detailed microRNA database focused on ruminant species.

The ever-increasing use of next-generation sequencing technologies to explore the genome has generated large quantities of data in recent years. Numerous publications have described several thousand sequences of microRNAs, all species included. A new database (RumimiR) has been created from the literature to provide a detailed description of microRNAs for three ruminant species: cattle, goats and sheep.

Puberty is a critical window for the impact of diet on mammary gland development in the rabbit.

Background: Nutritional changes can affect future lactation efficiency. In a rabbit model, an obesogenic diet initiated before puberty and pursued throughout pregnancy enhances mammary differentiation, but when started during the neonatal period can cause abnormal mammary development in early pregnancy. The aim of this study was to investigate the impact of an unbalanced diet administered during the pubertal period only.

Defects of the endoplasmic reticulum and changes to lipid droplet size in mammary epithelial cells due to miR-30b-5p overexpression are correlated to a reduction in Atlastin 2 expression.

During lactation, mammary epithelial cells secrete fat in the form of milk fat globules that originate from intracellular lipid droplets. These droplets may form de novo from the endoplasmic reticulum or be derived from existing lipid droplets; they then either grow because enzymes of triacylglycerol synthesis relocate from the reticulum to their surface, or due to fusion and fission with other droplets. The overexpression of miR-30b-5p in the developing mouse mammary gland impairs lactation, which includes an increase in lipid droplet size.

Sunflower oil supplementation affects the expression of miR-20a-5p and miR-142-5p in the lactating bovine mammary gland.

Oil supplementation in dairy cattle diets is used to modulate milk fat composition, as well as the expression of mammary lipogenic genes, whose regulation remains unclear. MiRNAs are small non-coding RNA considered as crucial regulators of gene expression, offering clues to explain the mechanism underlying gene nutriregulation. The present study was designed to identify miRNAs whose expression in the cow mammary gland is modulated by sunflower oil supplementation.

Phenotypic and Molecular Alterations in the Mammary Tissue of R-Spondin1 Knock-Out Mice during Pregnancy.

R-spondin1 (Rspo1) is a member of a secreted protein family which has pleiotropic functions in development and stem cell growth. Rspo1 knock-out mice are sex-reversed, but some remain sub-fertile, so they fail to nurse their pups. A lack of Rspo1 expression in the mammary gland results in an absence of duct side-branching development and defective alveolar formation.

Food Deprivation Affects the miRNome in the Lactating Goat Mammary Gland.

Background: Nutrition affects milk composition thus influencing its nutritional properties. Nutrition also modifies the expression of mammary genes, whose regulation is not fully understood. MicroRNAs (miRNA) are small non coding RNA which are important post-transcriptional regulators of gene expression by targeting messenger RNAs.

Annotation of the goat genome using next generation sequencing of microRNA expressed by the lactating mammary gland: comparison of three approaches.

Background: MicroRNAs (miRNA) are small endogenous non-coding RNA involved in the post-transcriptional regulation of specific mRNA targets. The first whole goat genome sequence became available in 2013, with few annotations. Our goal was to establish a list of the miRNA expressed in the mammary gland of lactating goats, thus enabling implementation of the goat miRNA repertoire and considerably enriching annotation of the goat genome.

No effect of an elevated miR-30b level in mouse milk on its level in pup tissues.

Recent reports have shown that ingested microRNAs may be transferred to blood, accumulate in tissues and exert canonical regulation on endogenous transcripts. In spite of several attempts to replicate these findings, they have not been confirmed and several questions remain. By using a transgenic mouse model presenting a high level of miR-30b in milk, the horizontal delivery of this microRNA via oral ingestion was studied in pups.

Characterisation and comparison of lactating mouse and bovine mammary gland miRNomes.

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.

Preeclampsia-like symptoms induced in mice by fetoplacental expression of STOX1 are reversed by aspirin treatment.

Preeclampsia (PE) is a common human-specific pregnancy disorder defined by hypertension and proteinuria during gestation and responsible for maternal and fetal morbimortality. STOX1, encoding a transcription factor, was the first gene associated with PE as identified by positional cloning approaches. Its overexpression in choriocarcinoma cells mimics the transcriptional consequences of PE in the human placenta.

Overexpression of miR-30b in the developing mouse mammary gland causes a lactation defect and delays involution.

Background: MicroRNA (miRNA) are negative regulators of gene expression, capable of exerting pronounced influences upon the translation and stability of mRNA. They are potential regulators of normal mammary gland development and of the maintenance of mammary epithelial progenitor cells. This study was undertaken to determine the role of miR-30b on the establishment of a functional mouse mammary gland.

Prion protein and Shadoo are involved in overlapping embryonic pathways and trophoblastic development.

The potential requirement of either the Prion or Shadoo protein for early mouse embryogenesis was recently suggested. However, the current data did not allow to precise the developmental process that was affected in the absence of both proteins and that led to the observed early lethal phenotype. In the present study, using various Prnp transgenic mouse lines and lentiviral vectors expressing shRNAs that target the Shadoo-encoding mRNA, we further demonstrate the specific requirement of at least one of these two PrP-related proteins at early developmental stages.

Expression of the prion-like protein Shadoo in the developing mouse embryo.

The prion-like protein Shadoo has been suggested to compensate for the lack of PrP in Prnp-knockout mice, explaining their lack of extreme phenotype. In adult mice, both PrP and Shadoo have shown overlapping expression patterns and shared functions. Their expression in the mouse embryo has also been suggested to be complementary, as invalidation of both genes results in embryonic lethality.

Generation of Sprn-regulated reporter mice reveals gonadic spatial expression of the prion-like protein Shadoo in mice.

The protein Shadoo (Sho) is a paralogue of prion protein, and encoded by the gene Sprn. Like prion protein it is primarily expressed in central nervous system, and has been shown to have a similar expression pattern in certain regions of the brain. We have generated reporter mice carrying a transgene encompassing the Sprn promoter, exon 1, intron 1 and the 5'-end of exon 2 driving expression of either the LacZ or GFP reporter gene to study the expression profile of Shadoo in mice.

Transcriptomic analysis brings new insight into the biological role of the prion protein during mouse embryogenesis.

The biological function of the Prion protein remains largely unknown but recent data revealed its implication in early zebrafish and mammalian embryogenesis. To gain further insight into its biological function, comparative transcriptomic analysis between FVB/N and FVB/N Prnp knockout mice was performed at early embryonic stages. RNAseq analysis revealed the differential expression of 73 and 263 genes at E6.

Brain transcriptional stability upon prion protein-encoding gene invalidation in zygotic or adult mouse.

Background: The physiological function of the prion protein remains largely elusive while its key role in prion infection has been expansively documented. To potentially assess this conundrum, we performed a comparative transcriptomic analysis of the brain of wild-type mice with that of transgenic mice invalidated at this locus either at the zygotic or at the adult stages.

Results: Only subtle transcriptomic differences resulting from the Prnp knockout could be evidenced, beside Prnp itself, in the analyzed adult brains following microarray analysis of 24 109 mouse genes and QPCR assessment of some of the putatively marginally modulated loci.

Zinc finger nuclease technology heralds a new era in mammalian transgenesis.

Non-mouse mammalian transgenesis is limited by its overall inefficiency and technical hurdles. Recent years have seen the emergence of two approaches that are applicable to most mammals. The first, based on lentivirus vectors, allows efficient generation of transgenic founders, most of them expressing the transgene.