Effect of dietary supplementation of yeast culture Saccharomyces cerevisiae in lactating female goats

This study was designed to investigate the effects of adding a novel yeast culture, Saccharomyces cerevisiae refermented sorghum distiller's dried grains with solubles (SSDDGS), to the diets of lactating female goats on lactation performance and lamb growth performance. We divided 10 lactating Dazu black goats of similar age, weight, and offspring into two groups: one fed a pelleted diet with 50 g/day SSDDGS (ET), and the other without SSDDGS as a control (EC) for 7 weeks. We monitor the weight changes of each goat and collect blood and milk samples from experimental ewes at specific times for hormone and milk composition determination. We use ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to detect metabolites in the serum of lactating ewes. Our results showed that SSDDGS supplementation significantly reduced female goats' average daily weight loss during weeks 2-4 of lactation and increased serum IGF-1 and prolactin levels at week 4 (p < 0.05). SSDDGS supplementation in early lactation significantly increased milk protein, lactose, and ash content (p < 0.05). UPLC-MS/MS analysis showed that SSDDGS changed the levels of 58 metabolites in the serum of lactating goats. These metabolites were mainly involved in the sohingolipid signaling pathway, and cysteine, methionine, and sphingolipid metabolism. In summary, Yeast culture SSDDGS reduced weight loss, enhanced milk quality, and modified metabolic profiles in early lactation goats, providing insight into the potential regulatory role and mechanism of yeast culture in lactation female goats.

Prolactin Modulates the Proliferation and Secretion of Goat Mammary Epithelial Cells via Regulating Sodium-Coupled Neutral Amino Acid Transporter 1 and 2

The prolactin (PRL) hormone is a major regulator of mammary gland development and lactation. However, it remains unclear whether and how PRL contributes to mammary epithelial cell proliferation and secretion. The Boer and Macheng black crossbred goats are superior in reproduction, meat, and milk, and are popular in Hubei province. To elucidate the mechanisms of PRL on mammary growth and lactation, to improve the local goat economic trade, we have performed studies on these crossbred goats during pregnancy and early lactation, and in goat mammary epithelial cells (GMECs). Here, we first found that the amino acid transporters of SNAT1 and SNAT2 expression in vivo and in vitro were closely associated with PRL levels, the proliferation and secretion of GMECs; knockdown and over-expression of SNAT1/2 demonstrated that PRL modulated the proliferation and lactation of GMECs through regulating SNAT1/2 expression. Transcriptome sequencing and qPCR assays demonstrated the effect of PRL on the transcriptional regulation of SNAT1 and SNAT2 in GMECs. Dual-luciferase reporter gene assays further verified that the binding of the potential PRL response element in the SNAT1/2 promoter regions activated SNAT1/2 transcription after PRL stimulation. Additionally, silencing of either PRLR or STAT5 nearly abolished PRL-stimulated SNAT1/2 promoter activity, suggesting PRLR-STAT5 signaling is involved in the regulation of PRL on the transcriptional activation of SNAT1/2. These results illustrated that PRL modulates the proliferation and secretion of GMECs via PRLR-STAT5-mediated regulation of the SNAT1/2 pathway. This study provides new insights into how PRL affects ruminant mammary development and lactation through regulation of amino acid transporters.

MicroRNA-148a Targets DNMT1 and PPARGC1A to Regulate the Viability, Proliferation, and Milk Fat Synthesis of Ovine Mammary Epithelial Cells

In this study, the expression profiles of miR-148a were constructed in eight different ovine tissues, including mammary gland tissue, during six different developmental periods. The effect of miR-148a on the viability, proliferation, and milk fat synthesis of ovine mammary epithelial cells (OMECs) was investigated, and the target relationship of miR-148a with two predicted target genes was verified. The expression of miR-148a exhibited obvious tissue-specific and temporal-specific patterns. miR-148a was expressed in all eight ovine tissues investigated, with the highest expression level in mammary gland tissue (p < 0.05). Additionally, miR-148a was expressed in ovine mammary gland tissue during each of the six developmental periods studied, with its highest level at peak lactation (p < 0.05). The overexpression of miR-148a increased the viability of OMECs, the number and percentage of Edu-labeled positive OMECs, and the expression levels of two cell-proliferation marker genes. miR-148a also increased the percentage of OMECs in the S phase. In contrast, transfection with an miR-148a inhibitor produced the opposite effect compared to the miR-148a mimic. These results indicate that miR-148a promotes the viability and proliferation of OMECs in Small-tailed Han sheep. The miR-148a mimic increased the triglyceride content by 37.78% (p < 0.01) and the expression levels of three milk fat synthesis marker genes in OMECs. However, the miR-148a inhibitor reduced the triglyceride level by 87.11% (p < 0.01). These results suggest that miR-148a promotes milk fat synthesis in OMECs. The dual-luciferase reporter assay showed that miR-148a reduced the luciferase activities of DNA methyltransferase 1 (DNMT1) and peroxisome proliferator-activated receptor gamma coactivator 1-A (PPARGC1A) in wild-type vectors, suggesting that they are target genes of miR-148a. The expression of miR-148a was highly negatively correlated with PPARGC1A (r = -0.789, p < 0.001) in ovine mammary gland tissue, while it had a moderate negative correlation with DNMT1 (r = -0.515, p = 0.029). This is the first study to reveal the molecular mechanisms of miR-148a underlying the viability, proliferation, and milk fat synthesis of OMECs in sheep.

Global changes of miRNA expression indicates an increased reprogramming efficiency of induced mammary epithelial cells by repression of miR-222-3p in fibroblasts

Background

Our previous studies have successfully reported the reprogramming of fibroblasts into induced mammary epithelial cells (iMECs). However, the regulatory relationships and functional roles of MicroRNAs (miRNAs) in the progression of fibroblasts achieving the cell fate of iMECs are insufficiently understood.

Methods

First, we performed pre-and post-induction miRNAs sequencing analysis by using high-throughput sequencing. Following that, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment studies were used to determine the primary roles of the significantly distinct miRNAs and targeted genes. Finally, the effect of miR-222-3p on iMECs fate reprogramming in vitro by transfecting.

Results

As a result goat ear fibroblasts (GEFs) reprogramming into iMECs activates a regulatory program, involving 79 differentially expressed miRNAs. Besides, the programming process involved changes in multiple signaling pathways such as adherens junction, TGF-β signaling pathway, GnRH secretion and the prolactin signaling pathway, etc. Furthermore, it was discovered that the expression of miR-222-3p downregulation by miR-222-3p inhibitor significantly increase the reprogramming efficiency and promoted lipid accumulation of iMECs.

Hormonal regulation of miRNA during mammary gland development

The mammary gland is a unique organ as most of its development occurs after birth through stages of proliferation, differentiation and apoptosis that are tightly regulated by circulating hormones and growth factors. Throughout development, hormonal cues induce the regulation of different pathways, ultimately leading to differential transcription and expression of genes involved in this process, but also in the activation or inhibition of post-transcriptional mechanisms of regulation. However, the role of microRNAs (miRNAs) in the different phases of mammary gland remodeling is still poorly understood. The objectives of this study were to analyze the expression of miRNA in key stages of mammary gland development in mice and to determine whether it could be associated with hormonal variation between stages. To do so, miRNAs were isolated from mouse mammary glands at stages of adulthood, pregnancy, lactation and involution, and sequenced. Results showed that 490, 473, 419, and 460 miRNAs are detected in adult, pregnant, lactating and involuting mice, respectively, most of them being common to all four groups, and 58 unique to one stage. Most genes could be divided into six clusters of expression, including two encompassing the highest number of miRNA (clusters 1 and 3) and showing opposite profiles of expression, reaching a peak at adulthood and valley at lactation, or showing the lowest expression at adulthood and peaking at lactation. GO and KEGG analyses suggest that the miRNAs differentially expressed between stages influence the expression of targets associated with mammary gland homeostasis and hormone regulation. To further understand the links between miRNA expression and hormones involved in mammary gland development, miRNAs were then sequenced in breast cells exposed to estradiol, progesterone, prolactin and oxytocin. Four, 38, 24 and 66 miRNAs were associated with progesterone, estradiol, prolactin, and oxytocin exposure, respectively. Finally, when looking at miRNAs modulated by the hormones, differentially expressed during mammary gland development, and having a pattern of expression that could be correlated with the relative levels of hormones known to be found in vivo, 16 miRNAs were identified as likely regulated by circulating hormones. Overall, our study brings a better understanding of the regulation of miRNAs throughout mammary gland development and suggests that there is a relationship between their expression and the main hormones involved in mammary gland development. Future studies will examine this role more in detail.

DNA methylation of GDF-9 and GHR genes as epigenetic regulator of milk production in Egyptian Zaraibi goat

BACKGROUND

DNA methylation is an epigenetic mechanism that takes place at gene promoters and a potent epigenetic marker to regulate gene expression.

OBJECTIVE

The study aimed to improve the milk production of Zaraibi goats by addressing the methylation pattern of two milk production-related genes: the growth hormone receptor (GHR) and the growth differentiation factor-9 (GDF-9).

METHODS

54 and 46 samples of low and high milk yield groups, respectively, were collected. Detection of methylation was assessed in two CpG islands in the GDF-9 promoter via methylation-specific primer assay (MSP) and in one CpG island across the GHR promoter using combined bisulfite restriction analysis (COBRA).

RESULTS

A positive correlation between the methylation pattern of GDF-9 and GHR and their expression levels was reported. Breeding season was significantly effective on both peak milk yield (PMY) and total milk yield (TMY), where March reported a higher significant difference in PMY than November. Whereas single birth was highly significant on TMY than multiple births. The 3rd and 4th parities reported the highest significant difference in PMY, while the 4th parity was the most effective one on TMY.

CONCLUSION

These results may help improve the farm animals' milk productive efficiency and develop prospective epigenetic markers to improve milk yield by epigenetic marker-assisted selection (eMAS) in goat breeding programs.

The role of breastfeeding in breast cancer prevention: a literature review

Breast cancer stands as the most prevalent malignancy globally. Despite the array of treatment options, its mortality rate continues to rise annually. Thus, reevaluation of factors directly linked to breast cancer emergence is imperative, alongside the development of more effective preventive measures. Estrogen levels, profoundly tied to reproduction, play a pivotal role in breast cancer development. Speculation centers on the potential of breastfeeding to mitigate cancer risk in women. However, the precise mechanism remains elusive. Breastfeeding is a modifiable reproductive factor extensively studied. Studies highlight a direct connection between lack of breastfeeding and breast cancer emergence, potentially linked to DNA methyltransferase expression alteration, aberrant methylation levels, pregnancy-associated plasma protein-A, cellular microenvironment, and oncogenes. This study reviews recent mechanisms underlying breastfeeding's role in reducing breast cancer incidence.

Progress in epigenetic regulation of milk synthesis, with particular emphasis on mRNA regulation and DNA methylation

Inadequate milk secretion and a lack of nutrients in humans and mammals are serious problems. It is of great significance to clarify the mechanisms of milk synthesis and treatment methods. Epigenetic modification, represented by RNA methylation, is an important way of gene expression regulation that profoundly affects human gene expression and participates in various physiological and pathological mechanisms. Epigenetic disorders also have an important impact on the production and secretion of milk. This review systematically summarized the research results of epigenetics in the process of lactation in PubMed, Web of Science, NSTL, and other databases and reviewed the effects of epigenetics on human and mammalian lactation, including miRNAs, circRNAs, lncRNAs, DNA methylations, and RNA methylations. The abnormal expression of miRNAs was closely related to the synthesis and secretion of milk fat, milk protein, and other nutrients in the milk of cattle, sheep, and other mammals. MiRNAs are also involved in the synthesis of human milk and the secretion of nutrients. CircRNAs and lncRNAs mainly target miRNAs and regulate the synthesis of nutrients in milk by ceRNA mechanisms. The abnormal expression of DNA and RNA methylation also has an important impact on milk synthesis. Epigenetic modification has the potential to regulate the milk synthesis of breast epithelial cells. Analyzing the mechanisms of human and mammalian milk secretion deficiency and nutrient deficiency from the perspective of epigenetics will provide a new perspective for the treatment of postpartum milk deficiency in pregnant women and mammalian milk secretion deficiency.

miR-497 Regulates LATS1 through the PPARG Pathway to Participate in Fatty Acid Synthesis in Bovine Mammary Epithelial Cells

Nutrient metabolism is required to maintain energy balance in animal organisms, and fatty acids play an irreplaceable role in fat metabolism. In this study, microRNA sequencing was performed on mammary gland tissues collected from cows during early, peak, and late lactation to determine miRNA expression profiles. Differentially expressed miRNA (miR-497) was selected for functional studies of fatty acid substitution. Simulants of miR-497 impaired fat metabolism [triacylglycerol (TAG) and cholesterol], whereas knockdown of miR-497 promoted fat metabolism in bovine mammary epithelial cells (BMECs) in vitro. In addition, in vitro experiments on BMECs showed that miR-497 could down-regulate C16:1, C17:1, C18:1, and C20:1 as well as long-chain polyunsaturated fats. Thus, these data expand the discovery of a critical role for miR-497 in mediating adipocyte differentiation. Through bioinformatics analysis and further validation, we identified large tumor suppressor kinase 1 (LATS1) as a target of miR-497. siRNA-LATS1 increased concentrations of fatty acids, TAG, and cholesterol in cells, indicating an active role of LATS1 in milk fat metabolism. In summary, miR-497/LATS1 can regulate the biological processes associated with TAG, cholesterol, and unsaturated fatty acid synthesis in cells, providing an experimental basis for further elucidating the mechanistic regulation of lipid metabolism in BMECs.

Prolactin promotes crop epithelial proliferation of domestic pigeons (Columba livia) through the Hippo signaling pathway

The purpose of this study was to investigate whether prolactin (PRL) regulates the proliferation of pigeon crop epithelium through the Hippo signaling pathway during the breeding cycle. Twenty-four pairs of adult pigeons were allotted to four groups by different breeding stages, and their crops and serum were sampled. Eighteen pairs of young pigeons were selected and divided into three groups for the injection experiments. The results showed that the serum PRL content and crop epithelial thickness of pigeons increased significantly at day 17 of incubation (I17) and day 1 of chick-rearing (R1). In males, the mRNA levels of yes-associated transcriptional regulator (YAP) and snail family transcriptional repressor 2 (SNAI2) were peaked at I17, and the gene levels of large tumor suppressor kinase 1 (LATS1), serine/threonine kinase 3 (STK3), TEA domain transcription factor 3 (TEAD3), connective tissue growth factor (CTGF), MYC proto-oncogene (c-Myc) and SRY-box transcription factor 2 (SOX2) reached the maximum value at R1. In females, the gene expression of YAP, STK3, TEAD3, and SOX2 reached the greatest level at I17, the expression profile of SAV1, CTGF, and c-Myc were maximized at R1. In males, the protein levels of LATS1 and YAP were maximized at R1 and the CTGF expression was upregulated at I17. In females, LATS1, YAP, and CTGF reached a maximum value at I17, and the expression level of phosphorylated YAP was minimized at I17 in males and females. Subcutaneous injection of prolactin (injected for 6 d, 10 μg per kg body weight every day) on the left crop of pigeons can promote the proliferation of crop epithelium by increasing the CTGF level and reducing the phosphorylation level of YAP. YAP-TEAD inhibitor verteporfin (injection for 6 d, 2.5 mg per kg body weight every day) can inhibit the proliferation of crop epithelium induced by prolactin by inhibiting YAP and CTGF expression. In conclusion, PRL can participate in crop cell proliferation of pigeons by promoting the expression of YAP and CTGF in Hippo pathway.

Melatonin Maintains Homeostasis and Potentiates the Anti-inflammatory Response in Staphylococcus aureus-Induced Mastitis through microRNA-16b/YAP1

Staphylococcus aureus is a highly infectious pathogen and is a considerable threat to food hygiene and safety. Although melatonin is thought to exert an ameliorative effect on bovine mastitis, the regulatory mechanisms are unclear. In this study, we first verified the therapeutic effect of melatonin against S. aureus in vitro and in vivo, a screening of differentially expressed miRNAs and mRNAs among the blank, and S. aureus and melatonin + S. aureus groups by high-throughput sequencing identified miR-16b and YAP1, which exhibited 1.95-fold upregulated and 1.05-fold downregulated expression, respectively. Moreover, epigenetic studies showed that S. aureus inhibited miR-16b expression by methylation (increased DNMT1 expression). Additionally, the DNMT1 expression level was significantly decreased by melatonin treatment, which might indicate that the inhibition of DNMT1 by melatonin reduces the effect of S. aureus on miR-16b. The flow cytometry, scanning and transmission electron microscopy, EdU assay, and cell morphology results indicated that miR-16b in bovine mammary epithelial cells (in vitro) and in mice (in vivo) can modulate the maintenance of homeostasis and potentiate the anti-inflammatory response. In addition, YAP1 was demonstrated to be the target gene of miR-16b through quantitative real-time polymerase chain reaction, western blot, RNA immunoprecipitation, and functional assays. This study indicates that melatonin inhibits S. aureus-induced inflammation via microRNA-16b/YAP1-mediated regulation, and these findings might provide a new strategy for the prevention of bovine mastitis, facilitating further studies good of zoonotic diseases caused by S. aureus infection.

Hormone supply to the pituitary gland: A comprehensive investigation of female‑related tumors (Review)

The hypothalamus acts on the pituitary gland after signal integration, thus regulating various physiological functions of the body. The pituitary gland includes the adenohypophysis and neurohypophysis, which differ in structure and function. The hypothalamus-hypophysis axis controls the secretion of adenohypophyseal hormones through the pituitary portal vein system. Thyroid-stimulating hormone, adrenocorticotropic hormone, gonadotropin, growth hormone (GH), and prolactin (PRL) are secreted by the adenohypophysis and regulate the functions of the body in physiological and pathological conditions. The aim of this review was to summarize the functions of female-associated hormones (GH, PRL, luteinizing hormone, and follicle-stimulating hormone) in tumors. Their pathophysiology was described and the mechanisms underlying female hormone-related diseases were investigated.

CRISPR/Cas9-Induced Knockout of miR-24 Reduces Cholesterol and Monounsaturated Fatty Acid Content in Primary Goat Mammary Epithelial Cells

In nonruminants, microRNA (miRNA)-24 plays an important role in lipid metabolism in adipose tissue and the liver. Although the abundance of miR-24 in ruminant mammary glands is the highest during peak lactation, its potential role in regulating the synthesis and secretion of fat into milk is unclear. This study aimed to identify the function of miR-24 in these processes using CRISPR/Cas9 technology in primary goat mammary epithelial cells (GMEC). A single clone containing a 66-nucleotide deletion between two sgRNAs mediating double-strand break (DSB) sites was obtained. The abundance of miR-24-3p and miR-24-5p encoded by the deleted sequence was decreased, whereas the target genes INSIG1 and FASN increased. In addition, miR-24 knockout reduced the gene abundance of genes associated with fatty acid and TAG synthesis and transcription regulator. Similarly, the content of cholesterol and monounsaturated fatty acid (MUFA) C18:1 decreased, whereas that of polyunsaturated fatty acids (PUFA) C18:2, C20:3, C20:4 and C20:5 increased. Subsequently, knocking down of INSIG1 but not FASN reversed the effect of miR-24 knockout, indicating that miR-24 modulated cholesterol and fatty acid synthesis mainly by targeting INSIG1. Overall, the present in vitro data demonstrated a critical role for miR-24 in regulating lipid and fatty acid synthesis and highlighted the possibility of manipulating milk components in dairy goats.

Organelles coordinate milk production and secretion during lactation: Insights into mammary pathologies

The mammary gland undergoes a spectacular series of changes during its development and maintains a remarkable capacity to remodel and regenerate during progression through the lactation cycle. This flexibility of the mammary gland requires coordination of multiple processes including cell proliferation, differentiation, regeneration, stress response, immune activity, and metabolic changes under the control of diverse cellular and hormonal signaling pathways. The lactating mammary epithelium orchestrates synthesis and apical secretion of macromolecules including milk lipids, milk proteins, and lactose as well as other minor nutrients that constitute milk. Knowledge about the subcellular compartmentalization of these metabolic and signaling events, as they relate to milk production and secretion during lactation, is expanding. Here we review how major organelles (endoplasmic reticulum, Golgi apparatus, mitochondrion, lysosome, and exosome) within mammary epithelial cells collaborate to initiate, mediate, and maintain lactation, and how study of these organelles provides insight into options to maintain mammary/breast health.

The Role of microRNAs in the Mammary Gland Development, Health, and Function of Cattle, Goats, and Sheep

Milk is an integral and therefore complex structural element of mammalian nutrition. Therefore, it is simple to conclude that lactation, the process of producing milk, is as complex as the mammary gland, the organ responsible for this biochemical activity. Nutrition, genetics, epigenetics, disease pathogens, climatic conditions, and other environmental variables all impact breast productivity. In the last decade, the number of studies devoted to epigenetics has increased dramatically. Reports are increasingly describing the direct participation of microRNAs (miRNAs), small noncoding RNAs that regulate gene expression post-transcriptionally, in the regulation of mammary gland development and function. This paper presents a summary of the current state of knowledge about the roles of miRNAs in mammary gland development, health, and functions, particularly during lactation. The significance of miRNAs in signaling pathways, cellular proliferation, and the lipid metabolism in agricultural ruminants, which are crucial in light of their role in the nutrition of humans as consumers of dairy products, is discussed.

Molecular mechanisms of mammary gland remodeling: A review of the homeostatic versus bisphenol a disrupted microenvironment

Mammary gland (MG) undergoes critical points of structural changes throughout a woman's life. During the perinatal and pubertal stages, MG develops through growth and differentiation to establish a pre-mature feature. If pregnancy and lactation occur, the epithelial compartment branches and differentiates to create a specialized structure for milk secretion and nurturing of the newborn. However, the ultimate MG modification consists of a regression process aiming to reestablish the smaller and less energy demanding structure until another production cycle happens. The unraveling of these fascinating physiologic cycles has helped the scientific community elucidate aspects of molecular regulation of proliferative and apoptotic events and remodeling of the stromal compartment. However, greater understanding of the hormonal pathways involved in MG developmental stages led to concern that endocrine disruptors such as bisphenol A (BPA), may influence these specific development/involution stages, called "windows of susceptibility". Since it is used in the manufacture of polycarbonate plastics and epoxy resins, BPA is a ubiquitous chemical present in human everyday life, exerting an estrogenic effect. Thus, descriptions of its deleterious effects on the MG, especially in terms of serum hormone concentrations, hormonal receptor expression, molecular pathways, and epigenetic alterations, have been widely published. Therefore, allied to a didactic description of the main physiological mechanisms involved in different critical points of MG development, the current review provides a summary of key mechanisms by which the endocrine disruptor BPA impacts MG homeostasis at different windows of susceptibility, causing short- and long-term effects.

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. This has led to the establishment of a role for epigenetic marks in milk component biosynthesis. This review aims to summarize the available knowledge regarding the involvement of the four main molecular mechanisms in epigenetics: DNA methylation, histone modifications, polycomb protein activity and non-coding RNA functions.

IGF-1 regulates the growth of fibroblasts and extracellular matrix deposition in pelvic organ prolapse

This study was carried out to observe the impact of insulin-like growth factor-1 (IGF-1) on human vaginal fibroblasts (HVFs) in the context of pelvic organ prolapse (POP) and to explore its effects on mitogen-activated protein kinases (MAPK) and nuclear factor-κB (NF-κB) signaling pathways. First, it was found that IGF-1 expression reduced in the vaginal wall tissues derived from POP compared to that in non-POP cases. Then the role of IGF-1 was explored in HVFs and thiazolyl blue tetrazolium bromide (MTT) and flow cytometry were used to detect cell viability and cell apoptosis. Western blot assay and quantitative real-time polymerase chain reaction were used to detect the protein and mRNA expression. The results showed that knockdown of IGF-1 inhibited the cell viability of HVFs, promoted the cell apoptosis of HVFs, and decreased the expression of types I and III collagen in HVFs, which was through inhibiting the expression of IGF-1 receptor and MAPK/NF-κB pathways. However, IGF-1 plasmid had the opposite effects on HVFs. In conclusion, our results showed that IGF-1 could activate MAPK and NF-κB pathways, thereby enhancing collagen metabolism and the growth of vaginal wall fibroblasts then to inhibit POP development.

Modulating Cytokine Production via Select Packaging and Secretion From Extracellular Vesicles

Cytokines are soluble factors that play vital roles in systemic function due to their ability to initiate and mediate cell-to-cell communication. Another important mechanism of intercellular communication that has gained significant attention in the past 10 years is the release of extracellular vesicles (EVs). EVs are released by all cells during normal physiology, in states of resting and activation, as well as during disease. Accumulating evidence indicates that cytokines may be packaged into EVs, and the packaging of cytokines into EVs, along with their ultimate secretion, may also be regulated by cytokines. Importantly, the repertoire of biomolecules packaged into EVs is shaped by the biological state of the cell (resting vs. activated and healthy vs. disease) and the EV biogenesis pathway involved, thus providing mechanisms by which EV packaging and secretion may be modulated. Given the critical role of cytokines in driving acute and chronic inflammatory and autoimmune diseases, as well as their role in establishing the tumor immune microenvironment, in this review, we will focus on these disease settings and summarize recent progress and mechanisms by which cytokines may be packaged within and modulated by EVs, as a therapeutic option for regulating innate and adaptive immunity.

PRL/microRNA-183/IRS1 Pathway Regulates Milk Fat Metabolism in Cow Mammary Epithelial Cells

The aim of the study was to understand the internal relationship between milk quality and lipid metabolism in cow mammary glands. A serial of studies was conducted to assess the molecular mechanism of PRL/microRNA-183/IRS1 (Insulin receptor substrate) pathway, which regulates milk fat metabolism in dairy cows. microRNA-183 (miR-183) was overexpressed and inhibited in cow mammary epithelial cells (CMECs), and its function was detected. The function of miR-183 in inhibiting milk fat metabolism was clarified by triglycerides (TAG), cholesterol and marker genes. There is a CpG island in the 5'-flanking promoter area of miR-183, which may inhibit the expression of miR-183 after methylation. Our results showed that prolactin (PRL) inhibited the expression of miR-183 by methylating the 5' terminal CpG island of miR-183. The upstream regulation of PRL on miR-183 was demonstrated, and construction of the lipid metabolism regulation network of microRNA-183 and target gene IRS1 was performed. These results reveal the molecular mechanism of PRL/miR-183/IRS1 pathway regulating milk fat metabolism in dairy cows, thus providing an experimental basis for the improvement of milk quality.

miR-497 regulates fatty acid synthesis via LATS2 in bovine mammary epithelial cells

Both mRNA and miRNA play an important role in the regulation of mammary fatty acid metabolism and milk fat synthesis.

FOXA1 Protein Expression in ER+ and ER- Breast Cancer in Relation to Parity and Breastfeeding in Black and White Women

BACKGROUND

Forkhead box protein A1 (FOXA1) promotes luminal differentiation, and hypermethylation of the gene can be a mechanism of developing estrogen receptor-negative (ER^-) breast cancer. We examined FOXA1 in breast tumor and adjacent normal tissue in relation to reproductive factors, particularly higher parity and no breastfeeding, that are associated with ER^- tumors.

METHODS

We performed IHC for FOXA1 in breast tumors (n = 1,329) and adjacent normal tissues (n = 298) in the Women's Circle of Health Study (949 Blacks and 380 Whites). Protein expression levels were summarized by histology (H) scores. Generalized linear models were used to assess FOXA1 protein expression in relation to reproductive factors by ER status.

RESULTS

ER-positive (ER⁺) versus ER^- tumors had higher FOXA1 protein expression (P < 0.001). FOXA1 expression was higher in tumor versus paired adjacent normal tissue in women with ER⁺ or non-triple-negative cancer (both P < 0.001), but not in those with ER^- or triple-negative cancer. Higher number of births (1, 2, and 3+) was associated with lower FOXA1 protein expression in ER⁺ tumors [differences in H score, or β = -8.5; 95% confidence interval (CI), -15.1 to -2.0], particularly among parous women who never breastfed (β = -10.4; 95% CI, -19.7 to -1.0), but not among those who breastfed (β = -7.5; 95% CI, -16.9 to 1.8). The associations for ER^- tumors were similar, although they were not statistically significant.

CONCLUSIONS

In this tumor-based study, higher parity was associated with lower FOXA1 expression in ER⁺ tumors, and breastfeeding may ameliorate the influence.

IMPACT

These findings contribute to our understanding of FOXA1 methylation and breast cancer etiology.

Screening candidate microR-15a- IRAK2 regulatory pairs for predicting the response to Staphylococcus aureus-induced mastitis in dairy cows

We established a mastitis model using exogenous infection of the mammary gland of Chinese Holstein cows with Staphylococcus aureus and extracted total RNA from S. aureus-infected and healthy mammary quarters. Differential expression of genes due to mastitis was evaluated using Affymetrix technology and results revealed a total of 1230 differentially expressed mRNAs. A subset of affected genes was verified via Q-PCR and pathway analysis. In addition, Solexa high-throughput sequencing technology was used to analyze profiles of miRNA in infected and healthy quarters. These analyses revealed a total of 52 differentially expressed miRNAs. A subset of those results was verified via Q-PCR. Bioinformatics techniques were used to predict and analyze the correlations among differentially expressed miRNA and mRNA. Results revealed a total of 329 pairs of negatively associated miRNA/mRNA, with 31 upregulated pairs of mRNA and 298 downregulated pairs of mRNA. Differential expression of miR-15a and interleukin-1 receptor-associated kinase-like 2 (IRAK2), were evaluated by western blot and luciferase reporter assays. We conclude that miR-15a and miR-15a target genes (IRAK2) constitute potential miRNA-mRNA regulatory pairs for use as biomarkers to predict a mastitis response.

MiR-16a Regulates Milk Fat Metabolism by Targeting Large Tumor Suppressor Kinase 1 (LATS1) in Bovine Mammary Epithelial Cells

Milk contains a number of beneficial fatty acids including short and medium chain and unsaturated conjugated and nonconjugated fatty acids. In this study, microRNA sequencing of mammary tissue collected in early-, peak-, mid-, and late-lactation periods was performed to determine the miRNA expression profiles. miR-16a was one of the differentially expressed miRNA and was selected for in-depth functional studies pertaining to fatty acid metabolism. The mimic of miR-16a impaired fat metabolism [triacylglycerol (TAG) and cholesterol] while knock-down of miR-16a promoted fat metabolism in vitro in bovine mammary epithelial cells (BMECs). In addition, the in vitro work with BMECs also revealed that miR-16a had a negative effect on the cellular concentration of cis 9-C18:1, total C18:1, C20:1, and C22:1 and long-chain polyunsaturated fatty acids. Therefore, these data suggesting a negative effect on fatty acid metabolism extend the discovery of the key role of miR-16a in mediating adipocyte differentiation. Through a combination of bioinformatics analysis, target gene 3' UTR luciferase reporter assays, and western blotting, we identified large tumor suppressor kinase 1 (LATS1) as a target of miR-16a. Transfection of siRNA-LATS1 into BMECs led to increases in TAG, cholesterol, and cellular fatty acid concentrations, suggesting a positive role of LATS1 in mammary cell fatty acid metabolism. In summary, data suggest that miR-16a regulates biological processes associated with intracellular TAG, cholesterol, and unsaturated fatty acid synthesis through LATS1. These data provide a theoretical and experimental framework for further clarifying the regulation of lipid metabolism in mammary cells of dairy cows.

Analysis of longissimus muscle quality characteristics and associations with DNA methylation status in cattle

BACKGROUND

As cattle represent one of the most important livestock species for meat production, control of muscle development in regards to quality is an important research focus.

OBJECTIVES

In this study, the phenotypic quality traits and its associations with DNA methylation levels of the longissimus muscle in two cattle breeds were studied.

METHODS

The pH value, water loss rate, fat and protein and fatty acid content were measured in three beef cattle breeds of longissimus mucle; The longissimus mucle was analyzed by MethylRAD-seq and RNA-seq. The differentially methylated and differentially expressed related genes were subjected to BSP.

RESULTS

Methylation status of longissimus mucle was analyzed by MethylRAD-seq. Compared with Simmental, there were 39 differentially methylated and expressed genes in muscle of Yunling cattle, and 123 differentially methylated and expressed genes in Wenshan muscle. A combined analysis of MethylRAD-seq and RNA-seq results revealed differential methylation and expression level of 18 genes between Simmental and Wenshan cattle, and 14 genes between Simmental and Yunling cattle. In addition, 28 genes were differentially methylated between Wenshan and Yunling cattle. Results of promoter methylation analysis of ACAD11, FADS6 and FASN showed that the overall degree of DNA methylation of FADS6 and FASN was negatively correlated with their expression levels. Methylation level of FASN in Simmental was greater than Yunling and Wenshan. The degree of methylation at the FADS6 CpG4 site was significantly higher in Simmental than that in Yunling. The levels of methylation at the CpG7 locus of the Simmental and Yunling breeds were greater than Wenshan cattle. A negative correlation was detected between the methylation levels and the expression of FASN CpG1, CpG2, CpG3, CpG5, CpG7, and CpG10.

CONCLUSION

The functional and molecular regulatory mechanism of the genes related to meat quality can be revealed systematically from aspects of the genetic and epigenetic regulation. These studies will help to further explore the molecular mechanisms and phenotypic differences that regulate growth and quality of different breeds of cattle.

MicroRNA-145 regulates immune cytokines via targeting FSCN1 in Staphylococcus aureus-induced mastitis in dairy cows

Dairy cow mastitis is a detrimental factor in milk quality and food safety. Mastitis generally refers to inflammation caused by infection by pathogenic microorganisms. Our studies in recent years have revealed the role of miRNA regulation in Staphylococcus aureus-induced mastitis. In the present study, we overexpressed and suppressed miR-145 to investigate the function of miR-145 in Mac-T cells. Flow cytometry, ELISA and EdU staining were used to detect changes in the secretion of several Mac-T cytokines and in cell proliferation. We found that overexpression of miR-145 in Mac-T cells significantly reduced the secretion of IL-12 and TNF-α, but increased the secretion of IFN-γ; the proliferation of bovine mammary epithelial cells was also inhibited. Using quantitative real-time PCR (qRT-PCR), Western blotting and luciferase multiplex verification techniques, we found that miR-145 targeted and regulated FSCN1. Knock-down of FSCN1 significantly increased the secretion of IL-12, while the secretion of TNF-α was significantly downregulated in Mac-T cells. Upon S. aureus infection of mammary gland tissue, the body initiated inflammatory responses; Bta-miR-145 expression was downregulated, which reduced the inhibitory effect on the FSCN1 gene; and upregulation of FSCN1 expression promoted mammary epithelial cell proliferation to allow the recovery of damaged tissue. The results of the present study will aid in understanding the immune mechanism opposing S. aureus infection in dairy cows and will provide a laboratory research basis for the prevention and treatment of mastitis.

MicroRNA-106b Regulates Milk Fat Metabolism via ATP Binding Cassette Subfamily A Member 1 ( ABCA1) in Bovine Mammary Epithelial Cells

Research on the mechanisms that regulate milk fat synthesis in dairy cows is essential to identify potential molecular targets that in the long term can help develop appropriate molecular breeding programs. Although some studies have revealed that microRNA (miRNA) affect lipid metabolism by targeting specific genes, joint analysis of miRNA and target mRNA data from bovine mammary tissue has revealed few clues regarding the underlying mechanisms controlling milk fat synthesis. The objective of the present study was to use high-throughput sequencing and bioinformatics analysis to identify miRNA and mRNA pairs and explore further their potential roles in regulating milk fat synthesis. A total of 233 pairs of negatively associated miRNA and mRNA pairs were detected. Among those, there were 162 pairs in which the miRNAs were down-regulated and the target mRNAs were up-regulated. Among the identified miRNA, miR-106b can bind the 3'-UTR of the ATP binding cassette subfamily A member 1 ( ABCA1), a gene previously identified as having a positive association with bovine milk fat synthesis. The overexpression of miR-106b in bovine mammary epithelial cells caused a decrease in triglyceride and cholesterol content while the inhibition of miR-106b increased triglyceride and cholesterol content, confirming its role in lipid metabolism. The present study allowed for the construction of a miR-106b- ABCA1 regulatory network map, thus providing a theoretical basis to target this gene in the molecular breeding of dairy cows.