Lactogenic Differentiation Research Articles

Loss of STING impairs lactogenic differentiation.

Heightened energetic and nutrient demand during lactogenic differentiation of the mammary gland elicits upregulation of various stress responses to support cellular homeostasis. Here, we identify the stimulator of interferon genes (STING) as an immune supporter of the functional development of mouse mammary epithelial cells (MECs). An in vitro model of MEC differentiation revealed that STING is activated in a cGAS-independent manner to produce both type I interferons and proinflammatory cytokines in response to the accumulation of mitochondrial reactive oxygen species. Induction of STING activity was found to be dependent on the breast tumor suppressor gene single-minded 2 (SIM2). Using mouse models of lactation, we discovered that loss of STING activity results in early involution of #3 mammary glands, severely impairing lactational performance. Our data suggest that STING is required for successful functional differentiation of the mammary gland and bestows a differential lactogenic phenotype between #3 mammary glands and the traditionally explored inguinal 4|9 pair. These findings affirm unique development of mammary gland pairs that is essential to consider in future investigations into normal development and breast cancer initiation.

Epigenetic impact of hypothyroidism on the functional differentiation of the mammary gland in rats

Mammary gland (MG) lactogenic differentiation involves epigenetic mechanisms. We have previously shown that hypothyroidism (HypoT) alters the MG transcriptome in lactation. However, the role of thyroid hormones (T3 and T4 a. k.a. THs) in epigenetic differentiation of MG is still unknown. We used a model of post-lactating HypoT rats to study in MG: a) Methylation and expression level of Gata3, Elf5, Stat6, Stat5a, Stat5b; b) Expression of Lalba, IL-4Rα and Ncoa1 mRNA; c) Histone H3 acetylation and d) Estrogen and progesterone concentration in serum. HypoT increases the estrogen serum level, decreases the progesterone level, promotes methylation of Stat5a, Stat5b and Stat6, decreasing their mRNA level and of its target genes (Lalba and IL-4Rα) and increases the Ncoa1 mRNA expression and histone H3 acetylation level. Our results proved that HypoT alters the post-lactation MG epigenome and could compromise mammary functional differentiation.

Nuclear VANGL2 Inhibits Lactogenic Differentiation.

Planar cell polarity (PCP) proteins coordinate tissue morphogenesis by governing cell patterning and polarity. Asymmetrically localized on the plasma membrane of cells, transmembrane PCP proteins are trafficked by endocytosis, suggesting they may have intracellular functions that are dependent or independent of their extracellular role, but whether these functions extend to transcriptional control remains unknown. Here, we show the nuclear localization of transmembrane, PCP protein, VANGL2, in the HCC1569 breast cancer cell line, and in undifferentiated, but not differentiated, HC11 cells that serve as a model for mammary lactogenic differentiation. The loss of Vangl2 function results in upregulation of pathways related to STAT5 signaling. We identify DNA binding sites and a nuclear localization signal in VANGL2, and use CUT&RUN to demonstrate recruitment of VANGL2 to specific DNA binding motifs, including one in the Stat5a promoter. Knockdown (KD) of Vangl2 in HC11 cells and primary mammary organoids results in upregulation of Stat5a, Ccnd1 and Csn2, larger acini and organoids, and precocious differentiation; phenotypes are rescued by overexpression of Vangl2, but not Vangl2ΔNLS. Together, these results advance a paradigm whereby PCP proteins coordinate tissue morphogenesis by keeping transcriptional programs governing differentiation in check.

PAPAS promotes differentiation of mammary epithelial cells and suppresses breast carcinogenesis

Extensive remodeling of the female mammary epithelium during development and pregnancy has been linked to cancer susceptibility. The faithful response of mammary epithelial cells (MECs) to hormone signaling is key to avoiding breast cancer development. Here, we show that lactogenic differentiation of murine MECs requires silencing of genes encoding ribosomal RNA (rRNA) by the antisense transcript PAPAS. Accordingly, knockdown of PAPAS derepresses rRNA genes, attenuates the response to lactogenic hormones, and induces malignant transformation. Restoring PAPAS levels in breast cancer cells reduces tumorigenicity and lung invasion and activates many interferon-regulated genes previously linked to metastasis suppression. Mechanistically, PAPAS transcription depends on R-loop formation at the 3' end of rRNA genes, which is repressed by RNase H1 and replication protein A (RPA) overexpression in breast cancer cells. Depletion of PAPAS and upregulation of RNase H1 and RPA in human breast cancer underpin the clinical relevance of our findings.

Inhibiting SETD7 methyl-transferase activity impairs differentiation, lipid metabolism and lactogenesis in mammary epithelial cells.

SETD7 (SET7/9, KMT7) is a lysine methyltransferase that targets master regulators of cell proliferation and differentiation. Here, the impact of inhibiting SETD7 catalytic activity on mammary epithelial cell differentiation was studied by focusing on genes associated with epithelial differentiation, lactogenesis, and lipid metabolism in HC11 and EpH4 cell lines. Setd7 mRNA and protein levels were induced upon lactogenic differentiation in both cell lines. Inhibition of SETD7 activity by the compound (R)-PFI-2 increased cell proliferation and downregulated E-cadherin, beta-catenin, lactoferrin, insulin-like growth factor binding protein 5, and beta-casein levels. In addition, inhibition of SETD7 activity affected the lipid profile and altered the mRNA expression of the phospholipid biosynthesis-related genes choline phosphotransferase 1, and ethanolamine-phosphate cytidylyltransferase. Altogether, the results suggest that inhibiting SETD7 catalytic activity impairs mammary epithelial and lactogenic differentiation.

Molecular complexity of mammary glands development: a review of lactogenic differentiation in epithelial cells

The mammary gland is a dynamic organ with various physiological processes like cellular proliferation, differentiation, and apoptosis during the pregnancy-lactation-involution cycle. It is essential to understand the molecular changes during the lactogenic differentiation of mammary epithelial cells (MECs, the milk-synthesizing cells). The MECs are organized as luminal milk-secreting cells and basal myoepithelial cells (responsible for milk ejection by contraction) that form the alveoli. The branching morphogenesis and lactogenic differentiation of the MECs prepare the gland for lactation. This process is governed by many molecular mediators including hormones, growth factors, cytokines, miRNAs, regulatory proteins, etc. Interestingly, various signalling pathways guide lactation and understanding these molecular transitions from pregnancy to lactation will help researchers design further research. Manipulation of genes responsible for milk synthesis and secretion will promote augmentation of milk yield in dairy animals. Identifying protein signatures of lactation will help develop strategies for persistent lactation and shortening the dry period in farm animals. The present review article discusses in details the physiological and molecular changes occurring during lactogenic differentiation of MECs and the associated hormones, regulatory proteins, miRNAs, and signalling pathways. An in-depth knowledge of the molecular events will aid in developing engineered cellular models for studies related to mammary gland diseases of humans and animals.

STAT5 confers lactogenic properties in breast tumorigenesis and restricts metastatic potential.

Signal transducer and activator of transcription 5 (STAT5) promotes cell survival and instigates breast tumor formation, and in the normal breast it also drives alveolar differentiation and lactogenesis. However, whether STAT5 drives a differentiated phenotype in breast tumorigenesis and therefore impacts cancer spread and metastasis is unclear. We found in two genetically engineered mouse models of breast cancer that constitutively activated Stat5a (Stat5aca) caused precancerous mammary epithelial cells to become lactogenic and evolve into tumors with diminished potential to metastasize. We also showed that STAT5aca reduced the migratory and invasive ability of human breast cancer cell lines in vitro. Furthermore, we demonstrated that STAT5aca overexpression in human breast cancer cells lowered their metastatic burden in xenografted mice. Moreover, RPPA, Western blotting, and studies of ChIPseq data identified several EMT drivers regulated by STAT5. In addition, bioinformatic studies detected a correlation between STAT5 activity and better prognosis of breast cancer patients. Together, we conclude that STAT5 activation during mammary tumorigenesis specifies a tumor phenotype of lactogenic differentiation, suppresses EMT, and diminishes potential for subsequent metastasis.

Long-term impact of hypothyroidism during gestation and lactation on the mammary gland.

The functional differentiation of the mammary gland (MG) is fundamental for the prevention of mammary pathologies. This process occurs throughout pregnancy and lactation, making these stages key events for the study of pathologies associated with development and differentiation. Many studies have investigated the link between mammary pathologies and thyroid diseases, but most have ignored the role of thyroid hormone (TH) in the functional differentiation of the MG. In this work, we show the long-term impact of hypothyroidism in an animal model whose lactogenic differentiation occurred at low TH levels. We evaluated the ability of the MG to respond to hormonal control and regulate cell cycle progression. We found that a deficit in TH throughout pregnancy and lactation induces a long-term decrease in Rb phosphorylation, increases p53, p21, Cyclin D1 and Ki67 expression, reduces progesterone receptor expression, and induces nonmalignant lesions in mammary tissue. This paper shows the importance of TH level control during mammary differentiation and its long-term impact on mammary function.

Hematopoietic PBX-interacting protein is a novel regulator of mammary epithelial cell differentiation.

Hematopoietic PBX-interacting protein (HPIP, also known as PBXIP1) is an estrogen receptor (ER) interacting protein that regulates estrogen-mediated breast cancer cell proliferation and tumorigenesis. However, its functional significance in the context of mammary gland development is unexplored. Here, we report that HPIP is required for prolactin (PRL)-induced lactogenic differentiation invitro. Molecular analysis of HPIP expression in mice revealed its induced expression at pregnancy and lactation stages of mammary gland. Moreover, PRL is a lactogenic hormone that controls pregnancy as well as lactation and induces Hpip/Pbxip1 expression in a signal transducer and activator of transcription 5a-dependent manner. Using mammary epithelial and lactogenic-competent cell lines, we further show that HPIP plays a regulatory role in PRL-mediated mammary epithelial cell differentiation, which is measured by acini formation, β-casein synthesis, and lipid droplet formation. Further mechanistic studies using pharmacological inhibitors revealed that HPIP modulates PRL-induced β-casein synthesis via phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) activation. This study also identified HPIP as a critical regulator of autocrine PRL signaling as treatment with the PRL receptor antagonist Δ1-9-G129R-hPRL restrained HPIP-mediated PRL synthesis, AKT activation, and β-casein synthesis in cultured HC11 cells. Interestingly, we also uncovered that microRNA-148a (miR-148a) antagonizes HPIP-mediated mammary epithelial cell differentiation. Together, our study identified HPIP as a critical regulator of PRL signaling and revealed a novel molecular circuitry involving PRL, HPIP, PI3K/AKT, and miR-148a that controls mammary epithelial cell differentiation invitro.

TMT based deep proteome analysis of buffalo mammary epithelial cellsand identification of novel protein signatures during lactogenic differentiation.

The lactating mammary gland harbours numerous matured alveoli with their lumen surrounded by differentiated mammary epithelial cells (MECs), which are exclusively involved in milk synthesis and secretion. Buffalo (Bubalus bubalis) is the second major milk-producing animal, and its physiology is different from cattle. The complete protein machinery involved in MECs differentiation is still not defined in ruminants, in particular, buffalo. Therefore, we have studied the differential expression of regulated proteins in the in vitro grown buffalo MECs (BuMECs) at different time points (on 3, 6, 12, and 15 days) of their differentiation in the presence of lactogenic hormones. TMT-based MS analysis identified 4,934 proteins; of them, 681 were differentially expressed proteins (DEPs). The principal component analysis suggested a highly heterogeneous expression of DEPs at the four-time points of hormone treatment, with most of them (307) attained the highest expression on 12 days. Bioinformatics analysis revealed the association of DEPs with 24 KEGG pathways. We observed few new proteins, namely ABCA13, IVL, VPS37, CZIB, RFX7, Rab5, TTLL12, SMEK1, GDI2, and TMEM131 in BuMECs. The function of one of the highly upregulated proteins, namely involucrin in the differentiation of BuMECs was confirmed based on biochemical inhibition assay. The results further conclude that the proteins with higher abundance can be considered as the potential biomarkers for differentiation, and they may have a significant association with the lactation process in buffalo too. The proteome dataset obtained can be used to understand the species-specific variations among other lactating animals.

DIGE-based identification of preferentially expressed proteins in early stage of lactogenic differentiation in buffalo (Bubalus bubalis) mammary epithelial cells

Proliferation and differentiation of mammary epithelial cells (MECs) is mediated by a complex cross-talk between cell and matrix, interaction among cells, hormones and growth factors. Differentiation of MECs leads to the synthesis and secretion of milk. The mechanism of switching from proliferation to differentiation is yet to be discovered at the molecular level. Differentiation is indicated by the formation of dome in in vitro cultured MECs, the first-ever change phenotypically. The present study was performed in vitro to identify the proteins expressed during initiation of differentiation of MECs in the early stage of lactogenesis using the buffalo MEC (BuMEC) cell line established in our laboratory. The cell line used was in 25th–30th passage. Differentiation was induced using lactogenic hormones (insulin, prolactin, and cortisol) and subcellular fractions (cytosolic and mitochondrial) from proliferative as well as differentiation stage were used to capture differentially expressed proteins (DEPs) by 2D DIGE and MALDI-TOF mass spectrometry. The signaling pathways associated with the DEPs were observed through bioinformatics analysis. The proteomics data were validated by qPCR analysis of selected proteins. The annexins such as annexin-I, II, and V and the S100 proteins (S100A4, S100A2, and S100A11) may have a crucial role in the initiation of differentiation and subsequently lactogenesis by MECs.

Effect of incubation temperature on lactogenic function of goat milk-derived mammary epithelial cells.

In general, goat mammary epithelial cells (MECs) are cultured in vitro under 37°C. We demonstrated previously that goat MECs differentiate under 37°C although their body temperature is approximately 39°C. This study aimed to investigate the influence of 39°C on lactogenic differentiation of goat milk-derived MECs. The results revealed that HSP70 gene was significantly elevated at 1h after an exposure to 39°C but declined at 48h thereafter. Oxidative stress status was not significantly affected by 39°C. Expressions of CSN2, β-GALT1, α-LA, and Akt genes tended to increase after the differentiation under 39°C. Secretion of lactose under 39°C was not significantly lower than 37°C. In conclusion, incubation temperature at 39°C does not dramatically affect lactogenic function of goat milk-derived MECs.

Serotonin stimulated parathyroid hormone related protein induction in the mammary epithelia by transglutaminase-dependent serotonylation.

Mammary-derived serotonin has been implicated in breast-to-bone communication during lactation by increasing parathyroid hormone related-protein (PTHrP) in the mammary gland. It is well established that PTHrP acts on the bone to liberate calcium for milk synthesis during lactation; however, the mechanism of serotonin’s regulation of PTHrP has not been fully elucidated. Recently, serotonylation has been shown to be involved in a variety of physiological processes mediated by serotonin. Therefore, we investigated whether serotonylation is involved in serotonin’s regulation of PTHrP in the mammary gland using lactogenically differentiated mouse mammary epithelial cells. We investigated the effect of increased intracellular serotonin using the antidepressant fluoxetine or 5-hydroxytryptophan (serotonin precursor), with or without transglutaminase inhibition and the corresponding action on PTHrP induction and activity. Treatment with fluoxetine or 5-hydroxytryptophan significantly increased intracellular serotonin concentrations and subsequently increased PTHrP gene expression, which was reduced with transglutaminase inhibition. Furthermore, we determined that transglutaminase activity is increased with lactogenic differentiation and 5-hydroxytryptophan or fluoxetine treatment. We investigated whether RhoA, Rac1, and Rab4 were potential serotonylation target proteins. We speculate that RhoA is potentially a serotonylation target protein. Our data suggest that serotonin regulates PTHrP induction in part through the process of serotonylation under lactogenic conditions in mouse mammary epithelial cells.

Autophagy regulates functional differentiation of mammary epithelial cells

ABSTRACT Mitochondria operate as a central hub for many metabolic processes by sensing and responding to the cellular environment. Developmental cues from the environment have been implicated in selective autophagy, or mitophagy, of mitochondria during cell differentiation and tissue development. Mitophagy occurring in this context, termed programmed mitophagy, responds to cell state rather than mitochondrial damage and is often accompanied by a metabolic transition. However, little is known about the mechanisms that engage and execute mitophagy under physiological or developmental conditions. As the mammary gland undergoes post-natal development and lactation challenges mitochondrial homeostasis, we investigated the contribution of mitochondria to differentiation of mammary epithelial cells (MECs). Using lactogenic differentiation of the HC11 mouse MEC line, we demonstrated that HC11 cells transition to a highly energetic state during differentiation by engaging both oxidative phosphorylation and glycolysis. Interestingly, this transition was lost when autophagy was inhibited with bafilomycin A1 or knockdown of Atg7 (autophagy related 7). To evaluate the specific targeting of mitochondria, we traced mitochondrial oxidation and turnover in vitro with the fluorescent probe, pMitoTimer. Indeed, we found that differentiation engaged mitophagy. To further evaluate the requirement of mitophagy during differentiation, we knocked down the expression of Prkn/parkin in HC11 cells. We found that MEC differentiation was impaired in shPrkn cells, implying that PRKN is required for MEC differentiation. These studies suggest a novel regulation of MEC differentiation through programmed mitophagy and provide a foundation for future studies of development and disease associated with mitochondrial function in the mammary gland. Abbreviations: AA: antimycin A; ATG5: autophagy related 5; BAF: bafilomycin A1; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3 like; COX8A: cytochrome c oxidase subunit 8A; CQ: chloroquine; CSN2: casein beta; ECAR: extracellular acidification rate; FCCP: trifluoromethoxy carbonylcyanide phenylhydrazone; FUNDC1: FUN14 domain containing 1; HIF1A: hypoxia inducible factor 1 subunit alpha; L1: lactation day 1; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MEC: mammary epithelial cell; mitoQ: mitoquinol; mROS: mitochondrial reactive oxygen species; OCR: oxygen consumption rate; P: priming; P16: pregnancy day 16; PARP1: poly(ADP-ribose) polymerase 1; PINK1: PTEN induced kinase 1; PPARGC1A: PPARG coactivator 1 alpha; PRKN: parkin RBR E3 ubiquitin protein ligase; shNT: short hairpin non-targeting control; SQSTM1: sequestosome 1; STAT3: signal transducer and activator of transcription 3; TEM: transmission electron microscopy; TFAM: transcription factor A, mitochondrial; U: undifferentiated.

Laminin-binding integrins are essential for the maintenance of functional mammary secretory epithelium in lactation.

Integrin dimers α3/β1, α6/β1 and α6/β4 are the mammary epithelial cell receptors for laminins, which are major components of the mammary basement membrane. The roles of specific basement membrane components and their integrin receptors in the regulation of functional gland development have not been analyzed in detail. To investigate the functions of laminin-binding integrins, we obtained mutant mice with mammary luminal cell-specific deficiencies of the α3 and α6 integrin chains generated using the Cre-Lox approach. During pregnancy, mutant mice displayed decreased luminal progenitor activity and retarded lobulo-alveolar development. Mammary glands appeared functional at the onset of lactation in mutant mice; however, myoepithelial cell morphology was markedly altered, suggesting cellular compensation mechanisms involving cytoskeleton reorganization. Notably, lactation was not sustained in mutant females, and the glands underwent precocious involution. Inactivation of the p53 gene rescued the growth defects but did not restore lactogenesis in mutant mice. These results suggest that the p53 pathway is involved in the control of mammary cell proliferation and survival downstream of laminin-binding integrins, and underline an essential role of cell interactions with laminin for lactogenic differentiation.

TRPS1 acts as a context-dependent regulator of mammary epithelial cell growth/differentiation and breast cancer development.

The GATA-type zinc finger transcription factor TRPS1 has been implicated in breast cancer. However, its precise role remains unclear, as both amplifications and inactivating mutations in TRPS1 have been reported. Here, we used in vitro and in vivo loss-of-function approaches to dissect the role of TRPS1 in mammary gland development and invasive lobular breast carcinoma, which is hallmarked by functional loss of E-cadherin. We show that TRPS1 is essential in mammary epithelial cells, since TRPS1-mediated suppression of interferon signaling promotes in vitro proliferation and lactogenic differentiation. Similarly, TRPS1 expression is indispensable for proliferation of mammary organoids and in vivo survival of luminal epithelial cells during mammary gland development. However, the consequences of TRPS1 loss are dependent on E-cadherin status, as combined inactivation of E-cadherin and TRPS1 causes persistent proliferation of mammary organoids and accelerated mammary tumor formation in mice. Together, our results demonstrate that TRPS1 can function as a context-dependent tumor suppressor in breast cancer, while being essential for growth and differentiation of normal mammary epithelial cells.

Peg1/Mest, an imprinted gene, is involved in mammary gland maturation.

Imprinted genes, which are specific to mammals, play important roles in cell proliferation, differentiation, ontogeny, and other phenomena. Moreover, these genes are considered crucial in the research of mammalian evolution. In the current study, we investigated the association between the expression of paternally imprinted gene paternally expressed 1/mesoderm-specific transcript (Peg1/Mest) and the maturation of the mammary gland. Quantitative real-time polymerase chain reaction analysis of Peg1/Mest gene expression at different stages of mouse mammary gland maturation revealed that its expression increased during gestation but decreased during lactation. Immunohistochemical staining demonstrated that Peg1/Mest was expressed in mammary epithelial cells. We measured expression levels of Peg1/Mest and E-cadherin during mammary alveoli formation using immunofluorescence staining a cell model for mammary alveoli formation in a 3D culture system. We found that the onset of E-cadherin expression roughly coincided with the peak of Peg1/Mest expression. Moreover, we discovered that the formation and proliferation of alveoli were suppressed in Peg1/Mest knockdown mammary epithelial cells. These results suggest that Peg1/Mest plays a certain role in mammary alveoli formation. To clarify the role of Peg1/Mest in the lactogenic differentiation of mammary epithelial cells, we examined the lactogenic differentiation capability of Peg1/Mest-overexpressing HC11 cells. Application of a differentiation-inducing stimulus did not increase β-casein expression in Peg1/Mest-overexpressing HC11 cells. The current study for the first time reports the involvement of an imprinted gene in mammary gland maturation.

R-spondin3 Is Associated with Basal-Progenitor Behavior in Normal and Tumor Mammary Cells.

R-spondin3 (RSPO3) is a member of a family of secreted proteins that enhance Wnt signaling pathways in diverse processes, including cancer. However, the role of RSPO3 in mammary gland and breast cancer development remains unclear. In this study, we show that RSPO3 is expressed in the basal stem cell-enriched compartment of normal mouse mammary glands but is absent from committed mature luminal cells in which exogenous RSPO3 impairs lactogenic differentiation. RSPO3 knockdown in basal-like mouse mammary tumor cells reduced canonical Wnt signaling, epithelial-to-mesenchymal transition-like features, migration capacity, and tumor formation in vivo Conversely, RSPO3 overexpression, which was associated with some LGR and RUNX factors, highly correlated with the basal-like subtype among patients with breast cancer. Thus, we identified RSPO3 as a novel key modulator of breast cancer development and a potential target for treatment of basal-like breast cancers.Significance: These findings identify RSPO3 as a potential therapetuic target in basal-like breast cancers.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/16/4497/F1.large.jpg Cancer Res; 78(16); 4497-511. ©2018 AACR.

Comprehensive profiling of transcriptional networks specific for lactogenic differentiation of HC11\xa0mammary epithelial stem-like cells

The development of mammary gland as a lactogenic tissue is a highly coordinated multistep process. The epithelial cells of lactiferous tubules undergo profound changes during the developmental window of puberty, pregnancy, and lactation. Several hormones including estrogen, progesterone, glucocorticoids and prolactin act in concert, and orchestrate the development of mammary gland. Understanding the gene regulatory networks that coordinate proliferation and differentiation of HC11 Mammary Epithelial stem-like Cells (MEC) under the influence of lactogenic hormones is critical for elucidating the mechanism of lactogenesis in detail. In this study, we analyzed transcriptome profiles of undifferentiated MEC (normal) and compared them with Murine Embryonic Stem Cells (ESC) using next-generation mRNA sequencing. Further, we analyzed the transcriptome output during lactogenic differentiation of MEC following treatment with glucocorticoids (primed state) and both glucocorticoids and prolactin together (prolactin state). We established stage-specific gene regulatory networks in ESC and MEC (normal, priming and prolactin states). We validated the top up-and downregulated genes in each stage of differentiation of MEC by RT-PCR and found that they are comparable with that of RNA-seq data. HC11 MEC display decreased expression of Pou5f1 and Sox2, which is crucial for the differentiation of MEC, which otherwise ensure pluripotency to ESC. Cited4 is induced during priming and is involved in milk secretion. MEC upon exposure to both glucocorticoids and prolactin undergo terminal differentiation, which is associated with the expression of several genes, including Xbp1 and Cbp that are required for cell growth and differentiation. Our study also identified differential expression of transcription factors and epigenetic regulators in each stage of lactogenic differentiation. We also analyzed the transcriptome data for the pathways that are selectively activated during lactogenic differentiation. Further, we found that selective expression of chromatin modulators (Dnmt3l, Chd9) in response to glucocorticoids suggests a highly coordinated stage-specific lactogenic differentiation of MEC.

Spatiotemporal Dynamics of 3D Genome Architecture and Gene Expression during Lactogenic Differentiation of Murine Mammary Epithelial Cells

Spatiotemporal Dynamics of 3D Genome Architecture and Gene Expression during Lactogenic Differentiation of Murine Mammary Epithelial Cells