Regulation of milk protein gene expression

Unraveling the Genomic Association for Milk Production Traits and Signatures of Selection of Cattle in a Harsh Tropical Environment

A study was designed to identify the genomic regions associated with milk production traits in a dairy cattle population reared by smallholder farmers in the harsh and challenging tropical savanna climate of Bengaluru, India. This study is a first-of-its-kind attempt to identify the selection sweeps for the dairy cattle breeds reared in such an environment. Two hundred forty lactating dairy cows reared by 68 farmers across the rural-urban transiting regions of Bengaluru were selected for this study. A genome-wide association study (GWAS) was performed to identify candidate genes for test-day milk yield, solids-not-fat (SNF), milk lactose, milk density and clinical mastitis. Furthermore, the cross-population extended haplotype homozygosity (XP-EHH) methodology was adopted to scan the dairy cattle breeds (Holstein Friesian, Jersey and Crossbred) in Bengaluru. Two SNPs, rs109340659 and rs41571523, were observed to be significantly associated with test-day milk yield. No significant SNPs were observed for the remaining production traits. The GWAS for milk lactose revealed one SNP (rs41634101) that was very close to the threshold limit, though not significant. The potential candidate genes fibrosin-like 1 (FBRSL) and calcium voltage-gated channel auxiliary subunit gamma 3 (CACN) were identified to be in close proximity to the SNP identified for test-day milk yield. These genes were observed to be associated with milk production traits based on previous reports. Furthermore, the selection signature analysis revealed a number of regions under selection for the breed-group comparisons (Crossbred-HF, Crossbred-J and HF-J). Functional analysis of these annotated genes under selection indicated pathways and mechanisms involving ubiquitination, cell signaling and immune response. These findings point towards the probable selection of dairy cows in Bengaluru for thermotolerance.

Diverse roles of glucocorticoids in the ruminant mammary gland: modulation of mammary growth, milk production, and mastitis

As endocrine hormones, glucocorticoids (GCs) play a pivotal role in numerous physiological processes, including mammary growth and lactation, circulatory metabolism, and responses to external stimuli. In the dairy industry, milk production from cows or goats is important for newborns and economic benefits. However, the milk yields from ruminant animals are always affected by the extent of mammary development, mammary disease, stress, or changes in metabolism. Thus, it is necessary to clarify how GCs changes in ruminants affect ruminant mammary gland function and mammary disease. This review summarizes the findings identifying that GCs modulate mammary gland development before lactation, but the stress-induced excessive release of GCs leads to milk production loss. In addition, the manner of GCs release may change under different concentrations of metabolites or during mastitis or inflammatory challenge. Nevertheless, exogenous GCs administration to animals may alleviate the clinical symptoms of mastitis. This review demonstrates that GCs offer a fascinating contribution to both physiologic and pathogenic conditions of the mammary gland in ruminant animals. Characterizing and understanding these changes or functions of endogenous and exogenous GCs in animals will be crucial for developing more endocrine regulators and therapies for improving milk production in ruminants.

Sequencing and Characterization of αs2-Casein Gene (CSN1S2) in the Old-World Camels Have Proven Genetic Variations Useful for the Understanding of Species Diversification

The CSN1S2 gene encodes αs2-casein, the third most abundant protein in camel milk. Despite its importance in foals, human nutrition, and dairy processing, the CSN1S2 gene in camels has received little attention. This study presents the first complete characterization of the CSN1S2 gene sequence in Old-World camels (Camelus bactrianus and Camelus dromedarius). Additionally, the gene promoter, consisting of 752 bp upstream of exon 1, was analyzed. The entire gene comprises 17 exons, ranging in length from 24 bp (exons 4, 8, 11, and 13) to 280 bp (exon 17). Interesting was the identification of the exon 12 in both species. The promoter analysis revealed 24 putative binding sites in the Bactrian camel and 22 in dromedary camel. Most of these sites were typical elements associated with milk protein, such as C/EBP-α, C/EBP-β, Oct-1, and AP1. The SNP discovery showed relatively high genetic diversity compared to other camel casein genes (CSN1S1, CSN2, and CSN3), with a total of 34 polymorphic sites across the two species. Particularly noteworthy is the transition g.311G>A in the CSN1S2 promoter, creating a new putative consensus binding site for a C/EBP-β in the Bactrian camel. At the exon level, two novel variants were found. One was detected in exon 6 of the Bactrian camel (g.3639C>G), resulting in an amino acid replacement, p.36Ile>Met. The second variant was found in noncoding exon 17 of dromedary CSN1S2 (g.1511G>T). Although this mutation occurs in the 3'-UnTranslated Region, it represents the first example of exonic polymorphism in the CSN1S2 for this species. This SNP also affects the binding sites of different microRNAs, including the seed sequence of the miRNA 4662a-3p, highlighting its role as a regulatory factor for CSN1S2 gene. A PCR-RFLP was set up for genotyping a dromedary Tunisian population (n = 157), and the minor allele frequency was found to be 0.27 for the G allele, indicating a potential yield improvement margin. The interspersed elements (INEs) analysis revealed 10 INEs covering 7.34% and 8.14% of the CSN1S2 sequence in the Bactrian and dromedary camels, respectively. Furthermore, six elements (A, B, F, H, I, and L) are shared among cattle and camels and are partially found in other ruminants, suggesting a common ancestral origin of these retrotransposons. Conversely, elements C, D, E, and G are specific to camels.

CEBPA-Regulated Expression of SOCS1 Suppresses Milk Protein Synthesis through mTOR and JAK2-STAT5 Signaling Pathways in Buffalo Mammary Epithelial Cells

Milk protein content is a key quality indicator of milk, and therefore elucidating its synthesis mechanism has been the focus of research in recent years. Suppressor of cytokine signaling 1 (SOCS1) is an important inhibitor of cytokine signaling pathways that can inhibit milk protein synthesis in mice. However, it remains elusive whether SOCS1 plays roles in the milk protein synthesis in the buffalo mammary gland. In this study, we found that the mRNA and protein expression levels of SOCS1 in buffalo mammary tissue during the dry-off period was significantly lower than those during lactation. Overexpression and knockdown experiments of SOCS1 showed that it influenced the expression and phosphorylation of multiple key factors in the mTOR and JAK2-STAT5 signaling pathways in buffalo mammary epithelial cells (BuMECs). Consistently, intracellular milk protein content was significantly decreased in cells with SOCS1 overexpression, while it increased significantly in the cells with SOCS1 knockdown. The CCAAT/enhancer binding protein α (CEBPA) could enhance the mRNA and protein expression of SOCS1 and its promoter activity in BuMECs, but this effect was eliminated when CEBPA and NF-κB binding sites were deleted. Therefore, CEBPA was determined to promote SOCS1 transcription via the CEBPA and NF-κB binding sites located in the SOCS1 promoter. Our data indicate that buffalo SOCS1 plays a significant role in affecting milk protein synthesis through the mTOR and JAK2-STAT5 signaling pathways, and its expression is directly regulated by CEBPA. These results improve our understanding of the regulation mechanism of buffalo milk protein synthesis.

Molecular Characterization and Phylogenetic Analysis of Casein Gene Family in Camelus ferus

Camel milk is known for its exceptional medical uses. It has been used since ancient times to treat infant diarrhea, hepatitis, insulin-dependent diabetes (IDDM), lactose intolerance, alcohol-induced liver damage, allergies, and autism. It has the power to treat several diseases, with cancer being the most significant. This study investigated the evolutionary relationship, physiochemical characteristics, and comparative genomic analysis of the casein gene family (CSN1S1, CSN2, CSN1S2, and CSN3) in Camelus ferus. Molecular phylogenetics showing the camelid species clustered casein nucleotide sequences into four groups: CSN1S1, CSN2, CSN1S2, and CSN3. The casein proteins from camels were evaluated and found to be unstable, thermostable, and hydrophilic. CSN1S2, CSN2, and CSN3 were acidic, but CSN1S1 was basic. CSN1S1 showed positive selection for one amino acid (Q), CSN1S2 and CSN2 for three (T, K, Q), and CSN3 showed no positive selection. We also compared high-milk-output species such as cattle (Bos Tarus) and low-milk-yield species such as sheep (Ovies Aries) with camels (Camel ferus) and discovered that YY1 sites are more frequent in sheep than in camels and very low in cattle. We concluded that the ratio of YY1 sites in these species may affect milk production.

Fascin is essential for mammary gland lactogenesis

Fascin expression has commonly been observed in certain subtypes of breast cancer, where its expression is associated with poor clinical outcome. However, its role in normal mammary gland development has not been elucidated. Here, we used a fascin knockout mouse model to assess its role in normal mammary gland morphogenesis and lactation. Fascin knockout was not embryonically lethal, and its effect on the litter size or condition at birth was minimal. However, litter survival until the weaning stage significantly depended on fascin expression solely in the nursing dams. Accordingly, pups that nursed from fascin^-/- dams had smaller milk spots in their abdomen, suggesting a lactation defect in the nursing dams. Mammary gland whole-mounts of pregnant and lactating fascin^-/- mice showed significantly reduced side branching and alveologenesis. Despite a typical composition of basal, luminal, and stromal subsets of mammary cells and normal ductal architecture of myoepithelial and luminal layers, the percentage of alveolar progenitors (ALDH⁺) in fascin^-/- epithelial fraction was significantly reduced. Further in-depth analyses of fascin^-/- mammary glands showed a significant reduction in the expression of Elf5, the master regulator of alveologenesis, and a decrease in the activity of its downstream target p-STAT5. In agreement, there was a significant reduction in the expression of the milk proteins, whey acidic protein (WAP), and β-casein in fascin^-/- mammary glands. Collectively, our data demonstrate, for the first time, the physiological role of fascin in normal mammary gland lactogenesis, an addition that could reveal its contribution to breast cancer initiation and progression.

Dynamic miRNA Landscape Links Mammary Gland Development to the Regulation of Milk Protein Expression in Mice

Simple Summary

Milk synthesis is vital for maintaining the normal growth of newborn animals. Abnormal mammary gland development leads to a decrease in female productivity and the overall productivity of animal husbandry. This study characterized the dynamic miRNA expression profile during the process of mammary gland development, and identified a novel miRNA regulating expression of β-casein—an important milk protein. The results are valuable for studying mammary gland development, increasing milk production, improving the survival rate of pups, and promoting the development of animal husbandry.

Abstract

Mammary gland morphology varies considerably between pregnancy and lactation status, e.g., virgin to pregnant and lactation to weaning. Throughout these critical developmental phases, the mammary glands undergo remodeling to accommodate changes in milk production capacity, which is positively correlated with milk protein expression. The purpose of this study was to investigate the microRNA (miRNA) expression profiles in female ICR mice’s mammary glands at the virgin stage (V), day 16 of pregnancy (P16d), day 12 of lactation (L12d), day 1 of forced weaning (FW1d), and day 3 of forced weaning (FW3d), and to identify the miRNAs regulating milk protein gene expression. During the five stages of testing, 852 known miRNAs and 179 novel miRNAs were identified in the mammary glands. Based on their expression patterns, the identified miRNAs were grouped into 12 clusters. The expression pattern of cluster 1 miRNAs was opposite to that of milk protein genes in mammary glands in all five different stages. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the predicted target genes of cluster 1 miRNAs were related to murine mammary gland development and lactation. Furthermore, fluorescence in situ hybridization (FISH) analysis revealed that the novel-mmu-miR424-5p, which belongs to the cluster 1 miRNAs, was expressed in murine mammary epithelial cells. The dual-luciferase reporter assay revealed that an important milk protein gene—β-casein (CSN2)—was regarded as one of the likely targets for the novel-mmu-miR424-5p. This study analyzed the expression patterns of miRNAs in murine mammary glands throughout five critical developmental stages, and discovered a novel miRNA involved in regulating the expression of CSN2. These findings contribute to an enhanced understanding of the developmental biology of mammary glands, providing guidelines for increasing lactation efficiency and milk quality.

Terminal differentiation and anti-tumorigenic effects of prolactin in breast cancer

Breast cancer is a major disease affecting women worldwide. A woman has 1 in 8 lifetime risk of developing breast cancer, and morbidity and mortality due to this disease are expected to continue to rise globally. Breast cancer remains a challenging disease due to its heterogeneity, propensity for recurrence and metastasis to distant vital organs including bones, lungs, liver and brain ultimately leading to patient death. Despite the development of various therapeutic strategies to treat breast cancer, still there are no effective treatments once metastasis has occurred. Loss of differentiation and increased cellular plasticity and stemness are being recognized molecularly and clinically as major derivers of heterogeneity, tumor evolution, relapse, metastasis, and therapeutic failure. In solid tumors, breast cancer is one of the leading cancer types in which tumor differentiation state has long been known to influence cancer behavior. Reprograming and/or restoring differentiation of cancer cells has been proposed to provide a viable approach to reverse the cancer through differentiation and terminal maturation. The hormone prolactin (PRL) is known to play a critical role in mammary gland lobuloalveolar development/remodeling and the terminal differentiation of the mammary epithelial cells promoting milk proteins gene expression and lactation. Here, we will highlight recent discoveries supporting an anti-tumorigenic role for PRL in breast cancer as a "pro/forward-differentiation" pathway restricting plasticity, stemness and tumorigenesis.

Effects of Organochlorine Pesticide Residues in Maternal Body on Infants

There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause damage to the lactation capacity of the mammary gland. In addition, because breast milk contains a lot of nutrients, it is the most important food source for new-born babies. If mothers are exposed to organochlorine pesticides (OCPs), the lipophilic organochlorine contaminants can accumulate in breast milk fat and be passed to the infant through breast milk. Therefore, it is necessary to investigate organochlorine contaminants in human milk to estimate the health risks of these contaminants to breastfed infants. In addition, toxic substances in the mother can also be passed to the fetus through the placenta, which is also something we need to pay attention to. This article introduces several types of OCPs, such as dichlorodiphenyltrichloroethane (DDT), methoxychlor (MXC), hexachlorocyclohexane (HCH), endosulfan, chlordane, heptachlorand and hexachlorobenzene (HCB), mainly expounds their effects on women's lactation ability and infant health, and provides reference for maternal and infant health. In addition, some measures and methods for the control of organochlorine pollutants are also described here.

Comparative Genomics, Evolutionary and Gene Regulatory Regions Analysis of Casein Gene Family in Bubalus bubalis

Buffalo is a luxurious genetic resource with multiple utilities (as a dairy, draft, and meat animal) and economic significance in the tropical and subtropical regions of the globe. The excellent potential to survive and perform on marginal resources makes buffalo an important source for nutritious products, particularly milk and meat. This study was aimed to investigate the evolutionary relationship, physiochemical properties, and comparative genomic analysis of the casein gene family (CSN1S1, CSN2, CSN1S2, and CSN3) in river and swamp buffalo. Phylogenetic, gene structure, motif, and conserved domain analysis revealed the evolutionarily conserved nature of the casein genes in buffalo and other closely related species. Results indicated that casein proteins were unstable, hydrophilic, and thermostable, although αs1-CN, β-CN, and κ-CN exhibited acidic properties except for αs2-CN, which behaved slightly basic. Comparative analysis of amino acid sequences revealed greater variation in the river buffalo breeds than the swamp buffalo indicating the possible role of these variations in the regulation of milk traits in buffalo. Furthermore, we identified lower transcription activators STATs and higher repressor site YY1 distribution in swamp buffalo, revealing its association with lower expression of casein genes that might subsequently affect milk production. The role of the main motifs in controlling the expression of casein genes necessitates the need for functional studies to evaluate the effect of these elements on the regulation of casein gene function in buffalo.

Bisphenol A and benzophenone-3 exposure alters milk protein expression and its transcriptional regulation during functional differentiation of the mammary gland in vitro

The plastic monomer and plasticizer bisphenol A (BPA), and the UV-filter benzophenone-3 (BP3) have been shown to have estrogenic activities that could alter mammary gland development. Our aim was to analyze whether BPA or BP3 direct exposure affects the functional differentiation of the mammary gland using an in vitro model. Mammary organoids were obtained and isolated from 8 week-old virgin female C57BL/6 mice and were differentiated on Matrigel with medium containing lactogenic hormones and exposed to: a) vehicle (0.01% ethanol); b) 1 × 10^-9 M or 1 × 10^-6 M BPA; or c) 1 × 10^-12 M, 1 × 10^-9 M or 1 × 10^-6 M BP3 for 72 h. The mRNA and protein expression of estrogen receptor alpha (ESR1) and progesterone receptor (PR) were assessed. In addition, mRNA levels of PR-B isoform, glucocorticoid receptor (GR), prolactin receptor (PRLR) and Stat5a, and protein expression of pStat5a/b were evaluated at 72 h. The mRNA and protein expression of milk proteins and their DNA methylation status were also analyzed. Although mRNA level of PRLR and GR was similar between treatments, mRNA expression of ESR1, total PR, PR-B and Stat5a was increased in organoids exposed to 1 × 10^-9 M BPA and 1 × 10^-12 M BP3. Total PR expression was also increased with 1 × 10^-6 M BPA. Nuclear ESR1 and PR expression was observed in all treated organoids; whereas nuclear pStat5a/b alveolar cells was observed only in organoids exposed to 1 × 10^-9 M BPA and 1 × 10^-12 M BP3. The beta-casein mRNA level was increased in both BPA concentrations and 1 × 10^-12 M BP3, which was associated with hypomethylation of its promoter. The beta-casein protein expression was only increased with 1 × 10^-9 M BPA or 1 × 10^-12 M BP3. In contrast, BPA exposure decreased alpha-lactalbumin mRNA expression and increased DNA methylation level in different methylation-sensitive sites of the gene. Also, 1 × 10^-9 M BPA decreased alpha-lactalbumin protein expression. Our results demonstrate that BPA or BP3 exposure alters milk protein synthesis and its transcriptional regulation during mammary gland differentiation in vitro.

Relationship between agrochemical compounds and mammary gland development and breast cancer

The exposure to agrochemical pesticides has been associated with several chronic diseases, including different types of cancer and reproductive disorders. In addition, because agrochemical pesticides may act as endocrine disrupting chemicals (EDCs) during different windows of susceptibility, they can increase the risk of impairing the normal development of the mammary gland and/or of developing mammary lesions. Therefore, the aim of this review is to summarize how exposure to different agrochemical pesticides suspected of being EDCs can interfere with the normal development of the mammary gland and the possible association with breast cancer. It has been shown that the mammary glands of male and female rats and mice are susceptible to exposure to non-organochlorine (vinclozolin, atrazine, glyphosate, chlorpyrifos) and organochlorine (endosulfan, methoxychlor, hexachlorobenzene) pesticides. Some of the effects of these compounds in experimental models include increased or decreased mammary development, impaired cell proliferation and steroid receptor expression and signaling, increased malignant cellular transformation and tumor development and angiogenesis. Contradictory findings have been found as to whether there is a causal link between the exposure or the pesticide body burden and breast cancer in humans. However, an association has been observed between pesticides (especially organochlorine compounds) and specific subtypes of breast cancer. Further studies are needed in both humans and experimental models to understand how agrochemical pesticides can induce or promote changes in the development, differentiation and/or malignant transformation of the mammary gland.

Camellia (Camellia oleifera Abel.) seed oil promotes milk fat and protein synthesis-related gene expression in bovine mammary epithelial cells

Camellia (Camellia oleifera Abel.) seed oil is a commonly used edible oil of China. In ancient Chinese literature, it is mentioned to be helpful for postpartum repair and lactation in women. Research on camellia seed oil (CO) as a feed additive for dairy cattle is less. We investigated the effect of CO on the expression of milk fat and protein syntheses-related genes in differentiated bovine mammary epithelial cells (MAC-T) using soybean oil (SO) as the control. The results showed that CO increased the expression of genes related to de novo synthesis of fatty acids including sterol regulatory element-binding protein 1 (SREBP1), acetyl-CoA carboxylase 1 (ACC), fatty acid synthase (FASN), lipoprotein lipase (LPL), and stearoyl-CoA desaturase (SCD) (p < .05). Among the milk protein genes analyzed, CO increased β-casein mRNA expression (p < .05) and decreased αS1-casein mRNA expression (p < .05) in MAC-T cells. CO upregulated the pathways related to milk protein synthesis with increased mRNA levels of phosphoinositide 3-kinase (PI3K), RAC-alpha serine/threonine-protein kinase (AKT1), and mammalian target of rapamycin (mTOR) (p < .05) in MAC-T cells. Ribosomal protein S6 kinase beta-1 (S6K1) gene was upregulated, and eukaryotic initiation factor 4E (eIF4E) gene (p < .05) was downregulated with CO treatment. The mRNA expression levels of janus kinase 2 (JAK2), activator of transcription 5-β (STAT5-β), and E74-like factor 5 (ELF5) were elevated in MAC-T cells treated with CO (p < .05). Meanwhile, the protein expression levels of S6K1, STAT5-β, phosphorylated mTOR (p-mTOR), p-S6K1, and p-STAT5-β increased in MAC-T cells treated with CO (p < .05). In summary, CO promoted β-casein synthesis by regulating PI3K-mTOR-S6K1 and JAK2-STAT5 signaling pathways and influenced fatty acid synthesis by regulating SREBP1-related genes in MAC-T cells. We need to further confirm the function of CO using in vivo models.

Effect of all-trans retinoic acid on casein and fatty acid synthesis in MAC-T cells

Objective

Caseins and fatty acids of milk are synthesized and secreted by the epithelial cells of the mammary gland. All-trans retinoic acid (ATRA), an active metabolite of vitamin A, has been shown to promote mammary development. This study was conducted to determine the effect of ATRA on casein synthesis and fatty acid composition in MAC-T cells.

Methods

MAC-T cells were allowed to differentiate for 4 d, treated with ATRA (0, 1.0, 1.5, and 2.0 μM), and incubated for 3 d. We analyzed the fatty acid composition, the mRNA expression of casein and fatty acid synthesis-related genes, and the phosphorylation of casein synthesis-related proteins of MAC-T cells by gas chromatography, quantitative polymerase chain reaction, and western blotting, respectively.

Results

In MAC-T cells, ATRA increased the mRNA levels of α_S1-casein and β-casein, janus kinase 2 (JAK2) and E74-like factor 5 of the signal transducer and activator of transcription 5 β (STAT5-β) pathway, ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic translation initiation factor 4E binding protein 1 of the mammalian target of rapamycin (mTOR) pathway, inhibited the mRNA expression of phosphoinositide 3-kinase and eukaryotic initiation factor 4E of the mTOR pathway, and promoted the phosphorylation of STAT5-β and S6K1 proteins. Additionally, ATRA increased the de novo synthesis of fatty acids, reduced the content of long-chain fatty acids, the ratio of monounsaturated fatty acids to saturated fatty acids (SFA), the ratio of polyunsaturated fatty acids (PUFA) to SFA, and the ratio of ω-6 to ω-3 PUFA. The mRNA levels of acetyl-CoA carboxylase 1, fatty acid synthase, lipoprotein lipase, stearoyl-CoA desaturase, peroxisome proliferator-activated receptor gamma, and sterol regulatory element-binding protein 1 (SREBP1) were enhanced by ATRA.

Conclusion

ATRA promotes the synthesis of casein by regulating JAK2/STAT5 pathway and downstream mTOR signaling pathway, and it improves the fatty acid composition of MAC-T cells by regulating SREBP1-related genes.

Hyperprolactinemia-inducing antipsychotics increase breast cancer risk by activating JAK-STAT5 in precancerous lesions

BACKGROUND

Psychiatric medications are widely prescribed in the USA. Many antipsychotics cause serum hyperprolactinemia as an adverse side effect; prolactin-Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) signaling both induces cell differentiation and suppresses apoptosis. It is controversial whether these antipsychotics increase breast cancer risk.

METHODS

We investigated the impact of several antipsychotics on mammary tumorigenesis initiated by retrovirus-mediated delivery of either ErbB2 or HRas or by transgenic expression of Wnt-1.

RESULTS

We found that the two hyperprolactinemia-inducing antipsychotics, risperidone and pimozide, prompted precancerous lesions to progress to cancer while aripiprazole, which did not cause hyperprolactinemia, did not. We observed that risperidone and pimozide (but not aripiprazole) caused precancerous cells to activate STAT5 and suppress apoptosis while exerting no impact on proliferation. Importantly, we demonstrated that these effects of antipsychotics on early lesions required the STAT5 gene function. Furthermore, we showed that only two-week treatment of mice with ruxolitinib, a JAK1/2 inhibitor, blocked STAT5 activation, restored apoptosis, and prevented early lesion progression.

CONCLUSIONS

Hyperprolactinemia-inducing antipsychotics instigate precancerous cells to progress to cancer via JAK/STAT5 to suppress the apoptosis anticancer barrier, and these cancer-promoting effects can be prevented by prophylactic anti-JAK/STAT5 treatment. This preclinical work exposes a potential breast cancer risk from hyperprolactinemia-inducing antipsychotics in certain patients and suggests a chemoprevention regime that is relatively easy to implement compared to the standard 5-year anti-estrogenic treatment in women who have or likely have already developed precancerous lesions while also requiring hyperprolactinemia-inducing antipsychotics.

Integration of GWAS, pathway and network analyses reveals novel mechanistic insights into the synthesis of milk proteins in dairy cows

The quantities and proportions of protein fractions have notable effects on the nutritional and technological value of milk. Although much is known about the effects of genetic variants on milk proteins, the complex relationships among the set of genes and pathways regulating the different protein fractions synthesis and secretion into milk in dairy cows are still not completely understood. We conducted genome-wide association studies (GWAS) for milk nitrogen fractions in a cohort of 1,011 Brown Swiss cows, which uncovered 170 significant single nucleotide polymorphism (SNPs), mostly located on BTA6 and BTA11. Gene-set analysis and the network-based Associated Weight Matrix approach revealed that the milk proteins associated genes were involved in several biological functions, particularly ion and cation transmembrane transporter activity and neuronal and hormone signalling, according to the structure and function of casein micelles. Deeper analysis of the transcription factors and their predicted target genes within the network revealed that GFI1B, ZNF407 and NR5A1 might act as master regulators of milk protein synthesis and secretion. The information acquired provides novel insight into the regulatory mechanisms controlling milk protein synthesis and secretion in bovine mammary gland and may be useful in breeding programmes aimed at improving milk nutritional and/or technological properties.

Cell Synchronization by Rapamycin Improves the Developmental Competence of Porcine SCNT Embryos

The cell cycle stage of donor cells influences the success of somatic cell nuclear transfer (SCNT). This study investigated the effects of rapamycin treatment on synchronization of porcine fibroblasts in comparison with control and serum-starved cells, SCNT donor cell viability, and SCNT-derived embryo development. Porcine fibroblasts were treated with 0.1, 1, 10, and 100 μM rapamycin for 1 or 3 days. The proportion of cells in G0/G1 phase was significantly higher among cells treated with 1 μM rapamycin for 3 days (D3-1R) than among control and serum-starved cells (p < 0.05). In comparison with control cells, rapamycin-treated cells exhibited reduced proliferation, similar to serum-starved cells. The viability (as assessed by the MTT assay) of D3-1R-treated cells was good, similar to control cells, showing their quality was maintained. To confirm nutrient regulation by rapamycin treatment, we checked the transcript levels of nutrient transporter genes (SLC2A2, SLC2A4, SLC6A14, and SLC7A1). These levels were significantly lower in D3-1R-treated cells than in control cells (p < 0.01). We performed SCNT with D3-1R-treated cells (SCNT(D3-1R)) to confirm the effect of cell cycle synchronization by rapamycin treatment. Although SCNT(D3-1R) embryos did not have an increased fusion rate, their cleavage and blastocyst formation rates were significantly higher than those of control embryos (p < 0.05). Regarding embryo quality, the numbers of total and apoptotic cells per blastocyst were increased and decreased, respectively, in SCNT(D3-1R) blastocysts. The mRNA levels of developmental (CDX2 and CDH1) and proapoptotic (FAS and CASP3) genes were significantly higher and lower, respectively, in SCNT(D3-1R) blastocysts than in control blastocysts (p < 0.05). These results demonstrate that rapamycin treatment affects the cell cycle synchronization of donor cells and enhances the developmental potential of porcine SCNT embryos.

Establishment of a 3D cell culture model of primary bovine mammary epithelial cells extracted from fresh milk

For the investigation of molecular processes underlying diseases of the bovine mammary gland, primary bovine mammary epithelial cells (pbMEC) are used. They are known to contribute to the innate immune system of the bovine mammary gland. The functionality of pbMEC depends on the maintenance of in vivo characteristics. So far, the optimization of pbMEC culture conditions was intended in a variety of experiments. For this purpose, most of the studies used stable cell lines or primary cells obtained from udder biopsies of slaughtered animals. By contrast, within our study, pbMEC of healthy and first lactating Brown Swiss cows were non-invasively isolated from fresh milk. The non-invasively isolated pbMEC were cultivated on the extracellular matrix-like scaffold Matrigel®_. Further, they were challenged with different compositions of proliferation media, containing lactogenic hormones and/or the essential amino acid L-lysine. Changes in expression levels of genes coding for milk proteins and for components of the janus kinase/signal transducers and activators of transcription (JAK-STAT) and mTOR pathways were analyzed by RT-qPCR. The secreted proteins were analyzed by LC-MS/MS measurements. We showed for the first time the establishment of a physiologically functional 3D cell culture model of pbMEC isolated from fresh milk. This represents a primary cell culture model system, based on non-invasive cell collection, that can be used to unravel physiological processes in an unbiased manner.

Hormonal regulation of platypus Beta-lactoglobulin and monotreme lactation protein genes

Endocrine regulation of milk protein gene expression in marsupials and eutherians is well studied. However, the evolution of this complex regulation that began with monotremes is unknown. Monotremes represent the oldest lineage of extant mammals and the endocrine regulation of lactation in these mammals has not been investigated. Here we characterised the proximal promoter and hormonal regulation of two platypus milk protein genes, Beta-lactoglobulin (BLG), a whey protein and monotreme lactation protein (MLP), a monotreme specific milk protein, using in vitro reporter assays and a bovine mammary epithelial cell line (BME-UV1). Insulin and dexamethasone alone provided partial induction of MLP, while the combination of insulin, dexamethasone and prolactin was required for maximal induction. Partial induction of BLG was achieved by insulin, dexamethasone and prolactin alone, with maximal induction using all three hormones. Platypus MLP and BLG core promoter regions comprised transcription factor binding sites (e.g. STAT5, NF-1 and C/EBPα) that were conserved in marsupial and eutherian lineages that regulate caseins and whey protein gene expression. Our analysis suggests that insulin, dexamethasone and/or prolactin alone can regulate the platypus MLP and BLG gene expression, unlike those of therian lineage. The induction of platypus milk protein genes by lactogenic hormones suggests they originated before the divergence of marsupial and eutherians.

Mammary cell-activating factor regulates the hormone-independent transcription of the early lactation protein (ELP) gene in a marsupial

The regulation of the tammar wallaby (Macropus eugenii) early lactation protein (ELP) gene is complex. ELP is responsive to the lactogenic hormones; insulin (I), hydrocortisone (HC) and prolactin (PRL) in mammary gland explants but could not be induced with lactogenic hormones in tammar primary mammary gland cells, nor in KIM-2 conditionally immortalised murine mammary epithelial cells. Similarly, ELP promoter constructs transiently-transfected into human embryonic kidney (HEK293T) cells constitutively expressing the prolactin receptor (PRLR) and Signal Transducer and Activator of Transcription (STAT)5A were unresponsive to prolactin, unlike the rat and mouse β-casein (CSN2) promoter constructs. Identification of the minimal promoter required for the hormone-independent transcription of tammar ELP in HEK293Ts and comparative analysis of the proximal promoters of marsupial ELP and the orthologous eutherian colostrum trypsin inhibitor (CTI) gene suggests that mammary cell-activating factor (MAF), an E26 transformation-specific (ETS) factor, may bind to an AGGAAG motif and activate tammar ELP.

Analysis of molecular heterogeneity of prolactin in human systemic lupus erythematosus

Hyperprolactinemia without clinical manifestations has been reported in some patients with systemic lupus erythematosus (SLE) because an increase of prolactin (PRL) is produced due to the BIG/BIG molecular variant (molecular variant, 150 kD). This research project aimed to determine levels of PRL: its bioactive form, the little nonglycosylated form (NGPRL) and variants with decreased bioactivity such as the BIG/BIG and the little glycosylated (GPRL), in 29 women and five men with SLE. PRL was assayed by IRMA with a kit from Immunotech Laboratory, the BIG/BIG form by precipitation with polyethyleneglycol 6000, and the NGPRL and GPRL by chromatography on Concanavalin-A-Sepharose. Increased PRL was detected in seven patients (20.6%) of whom three had increased BIG/BIG, six had increased GPRL and only four had increased NGPRL. The three cases with increased BIG/BIG were contrasted by chromatography on Sephadex G-100. No increased PRL or any of the other variants assayed were found in men. Results were similar when PRL was evaluated in the same blood samples by a different IRMA (DPC Laboratory). The etiology of the hyperprolactinemia in some of these patients is unknown, but their lack of symptoms (galactorrhea or amenorrhea) could be due to the BIG/BIG forms and basically to the glycosylation of the hormone. As for the relation between PRL and SLE activity, we found that hyperprolactinemic patients were younger, had a shorter history of illness, although it was not statistically significant, and a higher SLEDAI score. This would indicate a relation between hyperprolactinemia and lupus activity. The patients with increased BIG/BIG form also had a very active illness at the time of the study.

Targeted Vaccination against Human α-Lactalbumin for Immunotherapy and Primary Immunoprevention of Triple Negative Breast Cancer

We have proposed that safe and effective protection against the development of adult onset cancers may be achieved by vaccination against tissue-specific self-proteins that are “retired” from expression at immunogenic levels in normal tissues as we age, but are overexpressed in emerging tumors. α-Lactalbumin is an example of a “retired” self-protein because its expression in normal tissues is confined exclusively to the breast during late pregnancy and lactation, but is also expressed in the vast majority of human triple negative breast cancers (TNBC)—the most aggressive and lethal form of breast cancer and the predominant form that occurs in women at high genetic risk including those with mutated BRCA1 genes. In anticipation of upcoming clinical trials, here we provide preclinical data indicating that α-lactalbumin has the potential as a vaccine target for inducing safe and effective primary immunoprevention as well as immunotherapy against TNBC.

Regulatory roles of Oct proteins in the mammary gland

The expression of Oct-1 and -2 and their binding to the octamer motif in the mammary gland are developmentally and hormonally regulated, consistent with the expression of milk proteins. Both of these transcription factors constitutively bind to the proximal promoter of the milk protein gene β-casein and might be involved in the inhibition or activation of promoter activity via interactions with other transcription factors or cofactors at different developmental stages. In particular, the lactogenic hormone prolactin and glucocorticoids induce Oct-1 and Oct-2 binding and interaction with both the signal transducer and activator of transcription 5 (STAT5) and the glucocorticoid receptor on the β-casein promoter to activate β-casein expression. In addition, increasing evidence has shown the involvement of another Oct factor, Oct-3/4, in mammary tumorigenesis, making Oct-3/4 an emerging prognostic marker of breast cancer and a molecular target for the gene-directed therapeutic intervention, prevention and treatment of breast cancer. This article is part of a Special Issue entitled: The Oct Transcription Factor Family, edited by Dr. Dean Tantin.

STAT5 plays a critical role in regulating the 5'-flanking region of the porcine whey acidic protein gene in transgenic mice

The mammary gland serves as a valuable bioreactor system for the production of recombinant proteins in lactating animals. Pharmaceutical-grade recombinant protein can be harvested from the milk of transgenic animals that carry a protein of interest under the control of promoter regions genes encoding milk proteins. Whey acidic protein (WAP), for example, is predominantly expressed in the mammary gland and is regulated by lactating hormones during pregnancy. We cloned the 5'-flanking region of the porcine WAP gene (pWAP) to confirm the sequence elements in its promoter that are required for gene-expression activity. In the present study, we investigated how lactogenic hormones--including prolactin, hydrocortisone, and insulin--contribute to the transcriptional activation of the pWAP promoter region in mammalian cells, finding that these hormones activate STAT5 signaling, which in turn induce gene expression via STAT5 binding sites in its 5'-flanking region. To confirm the expression and hormonal regulation of the 5'-flanking region of pWAP in vivo, we generated transgenic mice expressing human recombinant granulocyte colony stimulating factor (hCSF2) in the mammary gland under the control of the pWAP promoter. These mice secreted hCSF2 protein in their milk at levels ranging from 242 to 1,274.8 ng/ml. Collectively, our findings show that the pWAP promoter may be useful for confining the expression of foreign proteins to the mammary gland, where they can be secreted along with milk.

A Neutralizing Prolactin Receptor Antibody Whose In Vivo Application Mimics the Phenotype of Female Prolactin Receptor-Deficient Mice

The prolactin receptor (PRLR) has been implicated in a variety of physiological processes (lactation, reproduction) and diseases (breast cancer, autoimmune diseases). Prolactin synthesis in the pituitary and extrapituitary sites is regulated by different promoters. Dopamine receptor agonists such as bromocriptine can only interfere with pituitary prolactin synthesis and thus do not induce a complete blockade of PRLR signaling. Here we describe the identification of a human monoclonal antibody 005-C04 that blocks PRLR-mediated signaling at nanomolar concentrations in vitro. In contrast to a negative control antibody, the neutralizing PRLR antibody 005-C04 inhibits signal transducer and activator of transcription 5 phosphorylation in T47D cells and proliferation of BaF3 cells stably expressing murine or human PRLRs in a dose-dependent manner. In vivo application of this new function-blocking PRLR antibody reflects the phenotype of PRLR-deficient mice. After antibody administration female mice become infertile in a reversible manner. In lactating dams, the antibody induces mammary gland involution and negatively interferes with lactation capacity as evidenced by reduced milk protein expression in mammary glands and impaired litter weight gain. Antibody-mediated blockade of the PRLR in vivo stimulates hair regrowth in female mice. Compared with peptide-derived PRLR antagonists, the PRLR antibody 005-C04 exhibits several advantages such as higher potency, noncompetitive inhibition of PRLR signaling, and a longer half-life, which allows its use as a tool compound also in long-term in vivo studies. Therefore, we suggest that this antibody will help to further our understanding of the role of auto- and paracrine PRLR signaling in health and disease.

Lactogenic hormone stimulation and epigenetic control of L-amino acid oxidase expression in lactating mammary glands

L-amino acid oxidase (LAO), a classic flavoprotein, shows antibacterial activity by producing hydrogen peroxide. LAO exists in many tissues such as salivary gland, thymus, spleen, small intestine and testis. In particular, LAO was highly expressed in mice milk and plays an important factor in innate immunity of mammary glands. However, the mechanism which LAO expression is regulated spatially and temporally in lactating mammary glands has been unclear. In this study, we showed the contribution of lactogenic hormone and epigenetic control on LAO gene expression. In monolayer of mammary epithelial cells, treatment of lactogenic hormone mixture, dexamethasone, insulin and prolactin, did not induce LAO mRNA expression and its promoter activity, even though one of milk protein β-casein expression was stimulated. However, increase of LAO expression was observed when the cells were treated with lactogenic hormones in a 3-dimensional culture. The results of chromatin immunoprecipitation analysis revealed that histone H3K18 acetylation increased and histone H3K27 tri-methylation decreased with lactation, which is associated with a period of high LAO expression. Moreover, the treatment of histone methylation inhibitor (DZNep) as well as histone deacetylation inhibitor (Trichostatine A) induced LAO expression in monolayer of mammary cells. Taken together, this is the first demonstration showing that LAO expression is induced in cell culture, and stimulation of lactogenic hormone and change of histone modification are promising signals to show highly expression of LAO in lactating mammary glands.

Generation of transgenic fibroblasts producing doxycycline-inducible human interferon-α or erythropoietin for a bovine mammary bioreactor

Interferon α (IFN-α) is a cytokine, produced predominantly in immune cells in response to pathogens, which interferes with viral replication in host cells. Another cytokine hormone, erythropoietin (EPO), is synthesized in interstitial fibroblasts of the kidney and acts as a stimulator for the production of red blood cells. Importantly, the two cytokines have been used in the treatment of certain hematological malignancies, including renal anemia. In the production of recombinant proteins, a transgenic expression system in bovine species is an efficient strategy for pharmaceutical production. In the present study, recombinant constructs capable of producing recombinant human IFN-α and EPO proteins were established and were generated containing the mammary gland-specific αS1-casein promoter region (between -175 and + 796 nt), as this promoter was revealed to have the highest level of activity in a previous promoter study. In order to minimize developmental toxicity by constitutive exogenous expression, a doxycycline (dox)-inducible system was introduced to the IFN-α/EPO-expressing constructs. Therefore, a unitary tetracycline (tet)-on the IFN-α/EPO vector was established, which combined a tet-on activator cassette controlled by the αS1-casein promoter, with a responder cassette encoding the IFN-α/EPO gene, controlled by the tetracycline response element (TRE) promoter. In these systems, the tet-controlled transactivator is affected by mammary gland-specific αS1-casein promoter, and binding of the transcriptional activator to the TRE results in transcription of the downstream IFN-α/EPO genes in the presence of dox. To assess this, the unitary tet-on IFN-α/EPO vector was introduced into a bovine mammary gland cell line (MAC-T), and the cells were then treated with 0.1-1 µg/ml dox. A marked increase was observed in the expression levels of IFN-α/EPO. In addition, bovine transgenic fibroblasts containing a mammary gland-specific and dox-inducible IFN-α/EPO construct were generated. These transgenic fibroblasts may provide a source for somatic cell nuclear transfer for the generation of transgenic cattle producing recombinant human IFN-α/EPO protein during lactation.

An evolutionarily conserved non-coding element in casein locus acts as transcriptional repressor

In mammals, the casein locus consists of stretches of non-coding DNA, the functions of most of which are unknown. These regions are believed to harbour elements responsible for spatio-temporally regulated expression of genes in this locus and so far, only a few such elements have been identified. In this study, we report a novel regulatory element in the casein locus. Comparative analysis of genomic DNA sequences of casein loci from different mammals identified a 147bp long evolutionarily conserved region (ECR) upstream of Odam, a gene in this locus. The ECR was found in close proximity of Odam gene in all the mammals examined. In-silico analysis predicted the ECR as a potential regulatory element. Functional analysis in different cell lines identified it as a unidirectional repressor element. From our findings we speculate that the ECR may be involved in the repression of the Odam expression in the mammary gland during lactation.

Production of transgenic dairy goat expressing human α-lactalbumin by somatic cell nuclear transfer

Production of human α-lactalbumin (hα-LA) transgenic cloned dairy goats has great potential in improving the nutritional value and perhaps increasing the yield of dairy goat milk. Here, a mammary-specific expression vector 5A, harboring goat β-lactoglobulin (βLG) promoter, the hα-LA gene, neo(r) and EGFP dual markers, was constructed. Then, it was effectively transfected into goat mammary epithelial cells (GMECs) and the expression of hα-LA was investigated. Both the hα-LA transcript and protein were detected in the transfected GMECs after the induction of hormonal signals. In addition, the 5A vector was introduced into dairy goat fetal fibroblasts (transfection efficiency ≈60-70%) to prepare competent transgenic donor cells. A total of 121 transgenic fibroblast clones were isolated by 96-well cell culture plates and screened with nested-PCR amplification and EGFP fluorescence. After being frozen for 8 months, the transgenic cells still showed high viabilities, verifying their ability as donor cells. Dairy goat cloned embryos were produced from these hα-LA transgenic donor cells by somatic cell nuclear transfer (SCNT), and the rates of fusion, cleavage, and the development to blastocyst stages were 81.8, 84.4, and 20.0%, respectively. A total of 726 reconstructed embryos derived from the transgenic cells were transferred to 74 recipients and pregnancy was confirmed at 90 days in 12 goats. Of six female kids born, two carried hα-LA and the hα-LA protein was detected in their milk. This study provides an effective system to prepare SCNT donor cells and transgenic animals for human recombinant proteins.

Collaborative interaction of Oct-2 with Oct-1 in transactivation of lactogenic hormones-induced β-casein gene expression in mammary epithelial cells

Octamer-binding transcription factor-1 (Oct-1) is found to mediate lactogenic hormones (prolactin and glucocorticoids, HP)-induced β-casein gene expression in mammary alveolar secretory epithelial cells (MECs). The mammary gland also expresses Oct-2 isoform. In this study, we show that Oct-2 is also involved in HP-induced β-casein expression. Oct-2 endogenously binds to the β-casein promoter in MECs, and HP induce Oct-2 binding activity via mechanisms other than increasing Oct-2 expression or inducing Oct-2 translocation to the nucleus. Oct-2 transactivates HP-induced β-casein gene expression and this function is exchangeable with Oct-1. In MECs, Oct-2 is found to physically interact with Oct-1 regardless of HP treatment. However, HP induce physical interactions of Oct-2 with both signal transducer and activator of transcription 5 (STAT5) and glucocorticoid receptor (GR). These results provided biochemical evidence that Oct-2 may form a heteromer with Oct-1 in induction of β-casein gene expression by HP in MECs.

Cloning and Molecular Characterization of Porcine β-casein Gene (CNS2)

The production of therapeutic proteins from transgenic animals is one of the most important successes of animal biotechnology. Milk is presently the most mature system for production of therapeutic proteins from a transgenic animal. Specifically, β-casein is a major component of cow, goat and sheep milk, and its promoter has been used to regulate the expression of transgenic genes in the mammary gland of transgenic animals. Here, we cloned the porcine β-casein gene and analyzed the transcriptional activity of the promoter and intron 1 region of the porcine β-casein gene. Sequence inspection of the 5′-flanking region revealed potential DNA elements including SRY, CdxA, AML-a, GATA-3, GATA-1 and C/EBP β. In addition, the first intron of the porcine β-casein gene contained the transcriptional enhancers Oct-1, SRY, YY1, C/EBP β, and AP-1, as well as the retroviral TATA box. We estimated the transcriptional activity for the 5′-proximal region with or without intron 1 of the porcine β-casein gene in HC11 cells stimulated with lactogenic hormones. High transcriptional activity was obtained for the 5′-proximal region with intron 1 of the porcine β-casein gene. The β-casein gene containing the mutant TATA box (CATAAAA) was also cloned from another individual pig. Promoter activity of the luciferase vector containing the mutant TATA box was weaker than the same vector containing the normal TATA box. Taken together, these findings suggest that the transcription of porcine β-casein gene is regulated by lactogenic hormone via intron 1 and promoter containing a mutant TATA box (CATAAAA) has poor porcine β-casein gene activity.

Effects of Arginine concentration on the in vitro expression of Casein and mTOR pathway related genes in mammary epithelial cells from dairy cattle

Arginine (Arg) is a conditionally-essential amino acid that is taken up by bovine mammary gland in excess of its output in milk. In this study we evaluated the effects of Arg concentration on the expression of casein and signaling pathway-related genes in mammary epithelial cells. The treatments (applied for 24 h) were designed to be devoid of Arg 0X (control; 0.00 mg/L), resemble the profile of Arg in casein (Arg 1X; 278.00 mg/L), be deficient [Arg 0.25X (69.50 mg/L) and Arg 0.5X (139.00 mg/L)], or be in excess of the amount in casein [Arg 2X (556.00 mg/L), Arg 4X (1,112 mg/L), and Arg 8X (2,224 mg/L)]. The expression of CSN1S, CSN3 and mTOR in the experimental groups was higher than those of the control group (P<0.05). Except for Arg 0.25X and Arg 8X (P>0.05), the expression of CSN1S2, CSN2 and JAK2 in other experimental groups was higher (P<0.05) than those in the control group. Except for Arg 8X (P>0.05), the expression of STAT5 in the other experimental groups was higher than those of the control (P<0.05). It also was observed that except for Arg 0.5X, the S6K expression was higher in other experimental groups than the control (P<0.05). In contrast, except for Arg 0.25X the other experimental groups resulted in lower 4EBP1 expression than the control (P<0.05). Among groups, the expression of CSN1S1, CSN1S2, CSN2, CSN3, JAK2, STAT5, mTOR and S6K gene was highest with Arg 2X (P<0.05); the reverse was true for 4EBP1 gene, with the lowest expression in this group (P<0.05). Taken together, Arg appears to play an important role in the transcriptional regulation of casein genes and mTOR-related genes in bovine mammary epithelial cells.

Toll-like receptor 4 regulates lipopolysaccharide-induced inflammation and lactation insufficiency in a mouse model of mastitis

Lactation mastitis is a debilitating inflammatory breast disease in postpartum women. Disease severity is associated with markers of inflammation rather than bacterial load, suggesting that immune-signaling pathways activated in the host are important in the disease pathology. The role of the innate pattern recognition receptor toll-like receptor 4 (TLR4) in progression and resolution of mastitislike disease was investigated in a mouse model. Lipopolysaccharide in Matrigel (10 μg/10 μl) was administered into the teat canal of lactating Tlr4 null mutant and wild-type mice to induce a localized area of inflammation. Mastitis induction resulted in a marked influx of RB6-positive neutrophils and F4/80-positive macrophages, which was higher in Tlr4(-/-) mice compared to wild-type mice. Tlr4 null mutation resulted in an altered immune-signaling fingerprint following induction of mastitis, with attenuated serum cytokines, including CXCL1, CCL2, interleukin 1 beta, and tumor necrosis factor alpha compared to wild-type mice. In both genotypes, the localized area of inflammation had resolved after 7 days, and milk protein was evident. However, the mammary glands of wild-type mice exhibited reduced capacity for milk production, with decreased percent area populated with glandular epithelium and decreased abundance of nuclear phosphorylated signal transducer and activator of transcription 5 compared to Tlr4 null mice. This study demonstrates that inflammatory pathways activated in the host are critically important in mastitis disease progression and suggests that lactation insufficiency associated with mastitis may be a consequence of TLR4-mediated inflammation, rather than the bacterial infection itself.

Human chorionic gonadotropin decreases human breast cancer cell proliferation and promotes differentiation

Human chorionic gonadotropin (hCG) is a glycoprotein produced by placental trophoblasts. Previous studies indicated that hCG could be responsible for the pregnancy-induced protection against breast cancer in women. It is reported that hCG decreases proliferation and invasion of breast cancer MCF-7 cells. Our research also demonstrates that hCG can reduce the proliferation of MCF-7 cells by downregulating the expression of proliferation markers, proliferating cell nuclear antigen (PCNA), and proliferation-related Ki-67 antigen (Ki-67). Interestingly, we find here that hCG elevates the state of cellular differentiation, as characterized by the upregulation of differentiation markers, β-casein, cytokeratin-18 (CK-18), and E-cadherin. Inhibition of hCG secretion or luteinizing hormone/hCG receptors (LH/hCGRs) synthesis can weaken the effect of hCG on the induction of cell differentiation. Furthermore, hCG can suppress the expression of estrogen receptor alpha. hCG activated receptor-mediated cyclic adenosine monophosphate/protein kinase A signaling pathway. These findings indicated that a protective effect of hCG against breast cancer may be associated with its growth inhibitory and differentiation induction function in breast cancer cells.

Generation of mastitis resistance in cows by targeting human lysozyme gene to β-casein locus using zinc-finger nucleases

Mastitis costs the dairy industry billions of dollars annually and is the most consequential disease of dairy cattle. Transgenic cows secreting an antimicrobial peptide demonstrated resistance to mastitis. The combination of somatic cell gene targeting and nuclear transfer provides a powerful method to produce transgenic animals. Recent studies found that a precisely placed double-strand break induced by engineered zinc-finger nucleases (ZFNs) stimulated the integration of exogenous DNA stretches into a pre-determined genomic location, resulting in high-efficiency site-specific gene addition. Here, we used ZFNs to target human lysozyme (hLYZ) gene to bovine β-casein locus, resulting in hLYZ knock-in of approximately 1% of ZFN-treated bovine fetal fibroblasts (BFFs). Gene-targeted fibroblast cell clones were screened by junction PCR amplification and Southern blot analysis. Gene-targeted BFFs were used in somatic cell nuclear transfer. In vitro assays demonstrated that the milk secreted by transgenic cows had the ability to kill Staphylococcus aureus. We report the production of cloned cows carrying human lysozyme gene knock-in β-casein locus using ZFNs. Our findings open a unique avenue for the creation of transgenic cows from genetic engineering by providing a viable tool for enhancing resistance to disease and improving the health and welfare of livestock.

Expression of the mammary gland-specific tammar wallaby early lactation protein gene is maintained in vitro in the absence of prolactin

Marsupial ELP (early lactation protein) and its eutherian orthologue, CTI (colostrum trypsin inhibitor) are expressed in the mammary gland only for the first 100 days postpartum (Phase 2A) in the tammar wallaby and during the bovine and canine colostrogenesis period 24-36h postpartum respectively. The factors which regulate temporal ELP and CTI expression are unknown. A tammar mammary gland explant culture model was used to investigate ELP gene regulation during pregnancy and early- and mid-lactation (Phase 1, 2A and 2B respectively). Tammar ELP expression could only be manipulated in explants in vitro if the gene was already expressed in vivo. ELP expression was maximal in Phase 1 explants treated with lactogenic hormones (insulin, hydrocortisone and prolactin), but unlike LGB (β-lactoglobulin), ELP expression was maintained in insulin or insulin and hydrocortisone over a 12-day culture period. In contrast, ELP was down-regulated when cultured without hormones. ELP could not be induced in explants cultured from mid-lactation which suggested that transcriptional repressors may prevent ELP expression during this period.

Maternal regulation of offspring development in mammals is an ancient adaptation tied to lactation

The developmental origins of health and disease (DOHaD) is a paradigm for understanding metabolic diseases of modern humans. Vulnerability to disease is linked to perturbations in development during critical time periods in fetal and neonatal life. These perturbations are caused by environmental signals, often generated or transduced by the mother. The regulation of mammalian development depends to a large extent on maternal biochemical signals to her offspring. We argue that this adaptation is ancient, and originated with the evolution of lactation. Lactation evolved earlier than live birth and before the extensive placental development of modern eutherian mammals. Milk contains a host of signaling molecules including nutrients, immunoglobulins, growth factors and metabolic hormones. As evidenced by marsupials, lactation originally served to supply the biochemical factors for growth and development for what is essentially a fetus to a weanling transitioning to independent existence. In placental mammals maternal signaling in earliest life is accomplished through the maternal-placental-fetal connection, with more of development shifted to in utero life. However, significant development occurs postpartum, supported by milk. Mothers of all taxa provide biochemical signals to their offspring, but for non-mammalian mothers the time window is short. Developing mammals receive maternal biochemical signals over an extended period. These signals serve to guide normal development, but also can vary in response to environmental conditions. The ancient adaptation of lactation resulted in a lineage (mammals) in which maternal regulation of offspring development evolved to a heightened degree, with the ability to modify development at multiple time points. Modern metabolic diseases may arise due to a mismatch between maternal regulation and eventual circumstances of the offspring, and due to a large proportion of mothers that exceed past evolutionary norms in body fat and pregnancy weight gain such that maternal signals may no longer be within the adaptive range.

Generation of five human lactoferrin transgenic cloned goats using fibroblast cells and their methylation status of putative differential methylation regions of IGF2R and H19 imprinted genes

BACKGROUND

Somatic cell nuclear transfer (SCNT) is a promising technique to produce transgenic cloned mammalian, including transgenic goats which may produce Human Lactoferrin (hLF). However, success percentage of SCNT is low, because of gestational and neonatal failure of transgenic embryos. According to the studies on cattle and mice, DNA methylation of some imprinted genes, which plays a vital role in the reprogramming of embryo in NT maybe an underlying mechanism.

METHODOLOGY/PRINCIPAL FINDINGS

Fibroblast cells were derived from the ear of a two-month-old goat. The vector expressing hLF was constructed and transfected into fibroblasts. G418 selection, EGFP expression, PCR, and cell cycle distribution were applied sequentially to select transgenic cells clones. After NT and embryo transfer, five transgenic cloned goats were obtained from 240 cloned transgenic embryos. These transgenic goats were identified by 8 microsatellites genotyping and southern blot. Of the five transgenic goats, 3 were lived after birth, while 2 were dead during gestation. We compared differential methylation regions (DMR) pattern of two paternally imprinted genes (H19 and IGF2R) of the ear tissues from the lived transgenic goats, dead transgenic goats, and control goats from natural reproduction. Hyper-methylation pattern appeared in cloned aborted goats, while methylation status was relatively normal in cloned lived goats compared with normal goats.

CONCLUSIONS/SIGNIFICANCE

In this study, we generated five hLF transgenic cloned goats by SCNT. This is the first time the DNA methylation of lived and dead transgenic cloned goats was compared. The results demonstrated that the methylation status of DMRs of H19 and IGF2R were different in lived and dead transgenic goats and therefore this may be potentially used to assess the reprogramming status of transgenic cloned goats. Understanding the pattern of gene imprinting may be useful to improve cloning techniques in future.

Buffalo alpha S1-casein gene 5'-flanking region and its interspecies comparison

The expression of milk protein genes is tightly regulated in a spatio-temporal manner through the combinatorial interaction of lactogenic hormones and a set of transcription factors mediating developmental and tissue-specific gene expression. The recruitment of a unique set of transcription factors is determined by the cis-regulatory motifs present in the gene promoter region. Here, we report the isolation, sequencing, structural analysis and interspecies comparison of the 5'cis-regulatory region of the buffalo alpha S1 (αS1)-casein gene. The proximal promoter region of the buffalo αS1-casein gene harbored the insertion of a 72-bp fragment of long interspersed nuclear element of the L1_BT retrotransposon family. Among the core and vertebrate-specific promoter elements, the motifs for the binding of Brn POU domain factors (BRNF), Lim homeodomain factors (LHXF), NK6 homeobox transcription factors (NKX6), nuclear factor kappa B/c-rel (NFKB), AT-rich interactive domain factor (ARID), Brn POU domain factor 5 (BRN5), pancreatic and intestinal homeodomain transcription factor (PDX1), Distal-less homeodomain transcription factors (DLXF), T-cell factor/lymphoid enhancer-binding factor-1 (LEFF) and GHF-1 pituitary-specific POU domain transcription factor (PIT1) were over-represented in the αS1-casein gene regulatory region (Z score >4.0). The Multiple EM for Motif elicitation predicted three motifs which consisted of the sequences known to bind mammary gland factor/signal transducer and activator of transcription 5 (MGF/STAT5), estrogen receptor-related alpha (ERα), steroidogenic factor 1 (SF1) and glucocorticoid receptor (GR), indicating their potential role in the mammary gland-specific gene expression. The interspecies comparison of the proximal promoter region revealed conserved sequences for TATA boxes and MGF/STAT5 in all species, whereas activator protein 1 (AP1), pregnancy-specific mammary nuclear factor (PMF), CCAAT/enhancer binding protein (C/EBP), double-stranded and single-stranded DNA-binding protein 1 (DS1 and SS), ying and yang factor 1 (YY1), and GR half-sites were among ruminants. The functional significance of the L1_BT retrotransposon insertion on the buffalo αS1-casein gene expression needs to be experimentally validated.

MUC1-C oncoprotein activates ERK→C/EBPβ signaling and induction of aldehyde dehydrogenase 1A1 in breast cancer cells

Aldehyde dehydrogenase 1A1 (ALDH1A1) activity is used as a marker of breast cancer stem cells; however, little is known about the regulation of ALDH1A1 expression. Mucin 1 (MUC1) is a heterodimeric protein that is aberrantly overexpressed in most human breast cancers. In studies of breast cancer cells stably silenced for MUC1 or overexpressing the oncogenic MUC1-C subunit, we demonstrate that MUC1-C is sufficient for induction of MEK → ERK signaling and that treatment with a MUC1-C inhibitor suppresses ERK activation. In turn, MUC1-C induces ERK-mediated phosphorylation and activation of the CCAAT/enhancer-binding protein β (C/EBPβ) transcription factor. The results further show that MUC1-C and C/EBPβ form a complex on the ALDH1A1 gene promoter and activate ALDH1A1 gene transcription. MUC1-C-induced up-regulation of ALDH1A1 expression is associated with increases in ALDH activity and is detectable in stem-like cells when expanded as mammospheres. These findings demonstrate that MUC1-C (i) activates a previously unrecognized ERK→C/EBPβ→ALDH1A1 pathway, and (ii) promotes the induction of ALDH activity in breast cancer cells.

Genomic architecture of bovine κ-casein and β-lactoglobulin

The objective of this study was to characterize the genetic architecture underlying the absolute concentrations of 2 important milk proteins, κ-casein (κ-CN) and β-lactoglobulin (β-LG), in a backcross population of (Holstein × Jersey) × Holstein cattle. A genome-wide association analysis was performed using a selective DNA pooling strategy and the Illumina BovineHD BeadChip assay [777,000 (777K) SNP markers; Illumina Inc., San Diego, CA]. After correction for multiple testing, 25 single nucleotide polymorphisms were found to be associated with κ-CN and 36 single nucleotide polymorphisms were associated with β-LG. A pathway association analysis revealed 15 Gene Ontology (GO) terms associated with the κ-CN trait and 28 GO terms associated with β-LG. In addition, several GO terms were associated with both milk proteins. Further analysis revealed that κ-CN and β-LG production is regulated by both kinase and phosphatase activity, including mechanisms regulating the extracellular matrix. These results are in concordance with the complex multihormonal process controlling the expression of milk proteins and interactions between mammary epithelial cells and extracellular matrix components. Although κ-CN and β-LG milk proteins are expressed by single genes, the results from this study showed that many loci are involved in the regulation of the concentration of these 2 proteins.

Comparison of progestin transcriptional profiles in rat mammary gland using Laser Capture Microdissection and whole tissue-sampling

INTRODUCTION

Investigation of molecular mechanisms by gene expression profiling gains increasingly importance in preclinical safety evaluation. However, assigning expressed genes to specific cell populations is nearly impossible if the investigated RNA originates from whole tissue extracts. In this regard, Laser Capture Microdissection (LCM) can be used to detect changes specific to individual cell types. The objective of this study was to investigate the use of LCM for characterisation of progestin-related gene expression changes in the mammary gland. Thus, transcriptional profiles of the mammary gland of rats treated with a non-steroidal progesterone-receptor ligand, promegestone, medroxyprogesterone acetate, progesterone or vehicle were compared using whole tissue homogenates or LCM-captured epithelial cells.

METHODS

Total RNA from 30 mammary glands was isolated from snap-frozen specimen of the whole tissue and from approximately 25.000-30.000 cells of cresyl violet stained frozen sections employing LCM. After amplification of averaged 0.2μg total RNA of LCM-captured samples, RNA was labelled, hybridised to Affymetrix GeneChips and analysed.

RESULTS

LCM-captured samples showed up to 3-fold more differentially expressed probe sets (progesterone) and up to 10-fold more downregulated (promegestone) probe sets than whole tissue samples implying high cell specificity. Moreover, mammary gland specific differentiation markers like whey acidic protein, alpha lactalbumin, casein alpha s1 and casein kappa showed up to 3.4-fold (alpha lactalbumin, vehicle) higher expression values. Multivariate data analyses revealed a clear separation of gene expression profiles according to the method used, suggesting an amplification dependent bias.

DISCUSSION

LCM transcriptional profiling provides highly cell-specific information. An amplification dependent bias was observed. The technical variability was shown to be smaller than the biological variability. For progestin-related transcriptional profiling of the mammary gland, whole tissue-sampling proved to yield more informative results. Therefore LCM should only be considered when cell-type specific gene expression profiles are necessary for an in depth evaluation.

Gene expression analysis of protein synthesis pathways in bovine mammary epithelial cells purified from milk during lactation and short-term restricted feeding

The objective of the study was to investigate selected key regulatory pathways of milk protein biosynthesis in primary bovine mammary epithelial cells (MECs) of dairy cows during the first 155 days of lactation. In addition, cows were exposed to feed restriction for a short period (FR) during different stages of lactation (week 4 and 21 pp) to study adjustment processes of molecular protein biosynthesis to metabolic challenge. Morning milk samples from twenty-four Holstein-Friesian cows were collected throughout the experimental period (n = 10 per animal). MEC from raw milk were purified using an immunomagnetic separation technique and used for real-time quantitative PCR analyses. As was seen in transcript abundances of all major milk proteins, mRNA levels of E74-like factor 5 (ELF5), an enhancer of signal transducer and activator of transcription (STAT) action, concomitantly decreased towards mid-lactation. Expression of ELF5 as well as of all milk protein genes showed a similar increase during FR in early lactation. Occasional changes in expression could be seen in other Janus kinase (JAK)/STAT factors and in mammalian target of rapamycin (mTOR) pathway elements. Amino acid transfer and glucose transporter and the β-casein expression were also partially affected. In conclusion, our findings suggest a pivotal role of the transcription factor ELF5 in milk protein mRNA expression with complementary JAK/STAT and mTOR signalling for the regulation of protein biosynthesis in the bovine mammary gland.

Interactions of the ubiquitous octamer-binding transcription factor-1 with both the signal transducer and activator of transcription 5 and the glucocorticoid receptor mediate prolactin and glucocorticoid-induced β-casein gene expression in mammary epithelial cells

Regulation of milk protein gene expression by lactogenic hormones (prolactin and glucocorticoids) provides an attractive model for studying the mechanisms by which protein and steroid hormones synergistically regulate gene expression. β-Casein is one of the major milk proteins and its expression in mammary epithelial cells is stimulated by lactogenic hormones. The signal transducer and activator of transcription 5 and glucocorticoid receptor are essential downstream mediators of prolactin and glucocorticoid signaling, respectively. Previous studies have shown that mutating the octamer-binding site of the β-casein gene proximal promoter dramatically reduces the hormonal induction of the promoter activity. However, little is known about the underlying molecular mechanisms. In this report, we show that lactogenic hormones rapidly induce the binding of octamer-binding transcription factor-1 to the β-casein promoter and this induction is not mediated by either increasing the expression of octamer-binding transcription factor-1 or inducing its translocation to the nucleus. Rather, lactogenic hormones induce physical interactions between the octamer-binding transcription factor-1, signal transducer and activator of transcription 5, and glucocorticoid receptor to form a ternary complex, and these interactions enhance or stabilize the binding of these transcription factors to the promoter. Abolishing these interactions significantly reduces the hormonal induction of β-casein gene transcription. Thus, our study indicates that octamer-binding transcription factor-1 may serve as a master regulator that facilitates the DNA binding of both signal transducer and activator of transcription 5 and glucocorticoid receptor in hormone-induced β-casein expression, and defines a novel mechanism of regulation of tissue-specific gene expression by the ubiquitous octamer-binding transcription factor-1.

Establishment of transgenic fibroblasts for producing recombinant human interferon-α and erythropoietin in bovine milk

Human interferon α (IFN-α) and erythropoietin (EPO) have been used for a variety of purposes in clinical medicine. Human IFN-α has been used to treat several types of viral infection and cancer, as well as renal anemia, via stimulation of erythrocyte formation in the bone marrow. Transgenic cattle are excellent candidates for pharmaceutical production for humans due to their ability to produce recombinant proteins in milk. The purpose of the present study was to generate bovine transgenic fibroblasts capable of producing recombinant human IFN-α and EPO proteins in transgenic cattle milk. First, we analyzed the promoter activities of various bovine milk protein genes in HC11 mouse mammary epithelial cells. The bovine milk protein gene promoters were cloned into the Luc gene in a promoter-less pGL3-Basic vector. Presence of the αS1-casein promoter (-175 to +796 nt) resulted in an up to 16-fold increase in luciferase activity compared with that of the promoter-less construct. In addition, the human IFN-α and EPO genes were identified as significantly overexpressed in HC11 cells compared with the promoter-less construct. Together, the present results demonstrate that the construct with the αS1-casein promoter may induce secretion of recombinant human IFN-α and EPO into bovine milk. Furthermore, we generated transgenic fibroblasts expressing human IFN-α and EPO cDNA controlled by the αS1-casein promoter and two screening markers, enhanced green fluorescent protein and neomycin resistance. These transgenic fibroblasts may be a source of somatic cells for generating transgenic cattle that produce recombinant human IFN-α and EPO proteins during lactation.