Stimulation of DNA synthesis in cultures of ovine mammary epithelial cells by insulin and insulin-like growth factors

1989 ◽  
Vol 123 (2) ◽  
pp. 319-326 ◽  
Author(s):  
S. J. Winder ◽  
A. Turvey ◽  
I. A. Forsyth
Keyword(s):  
Epithelial Cells ◽  
Dna Synthesis ◽  
Time Course ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Type I ◽  
Type I Igf Receptor ◽  
Pregnant Sheep ◽  
Igf I

ABSTRACT Ovine mammary epithelial cell clumps (30–90 μm) were plated onto attached gels of rat tail collagen in serum-free medium. Synthesis of DNA by these cultures could be stimulated by insulin-like growth factor-I (IGF-I) with a median effective dose of 5 μg/l, irrespective of stage of pregnancy. The time-course of response, however, was significantly slower in cells prepared from mammary tissue of non-pregnant and early pregnant sheep compared with sheep later in pregnancy. IGF-II had approximately 10% of the potency of IGF-I in stimulating DNA synthesis. Insulin acted over a wide concentration range and produced a maximum rate of stimulation not significantly different from that produced by IGF-I. These results are consistent with actions through the type-I IGF receptor although insulin may also act through its own receptor, possibly stimulating local IGF-I production. It is concluded that IGF-I is an important mitogen for ovine mammary epithelial cells. Journal of Endocrinology (1989) 123, 319–326

scholarly journals The Cyclin-Dependent Kinase Inhibitor p27 (Kip1) Regulates Both DNA Synthesis and Apoptosis in Mammary Epithelium But Is Not Required for Its Functional Development during Pregnancy

2003 ◽  
Vol 17 (12) ◽  
pp. 2436-2447 ◽  
Author(s):  
Elizabeth A. Davison ◽  
Christine S. L. Lee ◽  
Matthew J. Naylor ◽  
Samantha R. Oakes ◽  
Robert L. Sutherland ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Epithelial Cells ◽  
Dna Synthesis ◽  
Cyclin D1 ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Cyclin Dependent Kinase ◽  
Cdk2 Activity ◽  
P27 Kip1

Abstract Decreased expression of the cyclin-dependent kinase (CDK) inhibitor p27(Kip1) is common in breast cancer and is associated with poor prognosis. p27 is also an important mediator of steroidal regulation of cell cycle progression. We have therefore investigated the role of p27 in mammary epithelial cell proliferation. Examination of the two major functions of p27, assembly of cyclin D1-Cdk4 complexes and inhibition of Cdk2 activity, revealed that cyclin D1-Cdk4 complex formation was not impaired in p27−/− mammary epithelial cells in primary culture. However, cyclin E-Cdk2 activity was increased approximately 3-fold, indicating that the CDK inhibitory function of p27 is important in mammary epithelial cells. Increased epithelial DNA synthesis was observed during pregnancy in p27−/− mammary gland transplants, but this was paralleled by increased apoptosis. During pregnancy and at parturition, development and differentiation of p27+/+ and p27−/− mammary tissue were indistinguishable. These results demonstrate a role for p27 in both the proliferation and survival of mammary epithelial cells. However, the absence of morphological and cellular defects in p27−/− mammary tissue during pregnancy raises the possibility that loss of p27 in breast cancer may not confer an overall growth advantage unless apoptosis is also impaired.

Bovine mammary epithelial cells, initiators of innate immune responses to mastitis

2005 ◽  
Vol 45 (8) ◽  
pp. 757 ◽  
Author(s):  
C. Gray ◽  
Y. Strandberg ◽  
L. Donaldson ◽  
R. L. Tellam
Keyword(s):  
Immune Response ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Vital Role ◽  
Mammary Epithelial ◽  
Innate Immune ◽  
Mammary Tissue ◽  
Effector Cells ◽  
Bovine Mammary Epithelial Cells

Innate immunity plays a vital role in the protection of the bovine mammary gland against mastitis. Until recently, the migration of effector cells such as neutrophils and monocytes into the mammary gland was thought to provide the only defence against invading pathogens. However, mammary epithelial cells may also play an important role in the immune response, contributing to the innate defence of the mammary tissue through secretion of antimicrobial peptides and attraction of circulating immune effector cells. This paper reviews the innate immune pathways in mammary epithelial cells and examines their role in the initiation of an innate immune response to Gram-positive and Gram-negative bacteria.

Effect of INSIG1 on the milk fat synthesis of buffalo mammary epithelial cells

2020 ◽  
Vol 87 (3) ◽  
pp. 349-355
Author(s):  
Xinyang Fan ◽  
Lihua Qiu ◽  
Xiaohong Teng ◽  
Yongyun Zhang ◽  
Yongwang Miao
Keyword(s):  
Epithelial Cells ◽  
Milk Fat ◽  
Mammary Epithelial Cells ◽  
Strong Support ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Peak Period ◽  
Fat Synthesis ◽  
Milk Fat Synthesis

AbstractWe hypothesized that insulin-induced gene 1 (INSIG1) affects milk fat synthesis in buffalo. For this reason, the protein abundance of INSIG1 in the mammary tissue of buffalo during the peak period of lactation and dry-off period was evaluated. The results showed that the expression of INSIG1 at the peak of lactation was lower than that in the dry-off period. To explore the role of INSIG1 in milk fat synthesis, the buffalo mammary epithelial cells (BMECs) were isolated and purified from buffalo mammary tissue, and INSIG1 gene were overexpressed and knocked down by constructing the recombinant lentivirus vector of INSIG1 gene and transfecting into BMECs. Results revealed that INSIG1 overexpression decreased the expression of INSIG2, SREBP, PPARG, SCD, GPAM, DGAT2 and AGPAT6, which led to reduction of triglycerides (TAG) content in the cell. In contrast, knockdown of INSIG1 had a positive effect on mRNA expression of the above genes. Overall, the data provide strong support for a key role of INSIG1 in the regulation of milk fat synthesis in BMECs.

Lactogenic response of cultured mouse mammary epithelial cells to mouse placental lactogen

1986 ◽  
Vol 109 (2) ◽  
pp. 263-274 ◽  
Author(s):  
G. Thordarson ◽  
R. Villalobos ◽  
P. Colosi ◽  
J. Southard ◽  
L. Ogren ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Culture Medium ◽  
Mammary Epithelial Cells ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Placental Lactogen ◽  
Basic Medium ◽  
Mammary Tissue ◽  
Collagen Gels ◽  
Ovine Prolactin

ABSTRACT The ability of mouse placental lactogen (mPL), mouse prolactin (mPRL), mouse GH (mGH) and ovine prolactin (oPRL) to stimulate synthesis of α-lactalbumin was tested in a primary culture of mouse mammary gland epithelial cells. Mammary tissue was obtained from 10-day pregnant Swiss Webster mice, enzymatically dissociated and the cells were cultured on floating collagen gels for 5 days. The basic culture medium consisted of Nutrient Mixture F12/Dulbecco's Modified Eagle's Medium (1:1, v/v), containing 10 mg insulin/1, 5 mg cortisol/l, 10 μg epidermal growth factor/l, 5 g bovine serum albumin/l and 50 mg gentamycin/l. Mouse PL, mPRL, mGH and oPRL were added to the basic medium in concentrations from l μg/l to l mg/l. Accumulation of α-lactalbumin in the culture medium was measured. For that purpose, mouse α-lactalbumin was purified from mammary tissue obtained from lactating Swiss Webster mice and a radioimmunoassay was developed. Mouse PL, mPRL and oPRL stimulated a dose-dependent increase in α-lactalbumin secretion. Mouse GH also caused a significant, but dose-independent, increase in α-lactalbumin secretion. Mouse PL showed the greatest activity in stimulating α-lactalbumin secretion. It was concluded that mPL is an important lactogenic hormone in the latter half of pregnancy in the mouse, when circulating mPRL concentrations are low. J. Endocr. (1986) 109, 263–274

scholarly journals Developmental regulation of Bcl-2 family protein expression in the involuting mammary gland

1999 ◽  
Vol 112 (11) ◽  
pp. 1771-1783 ◽  
Author(s):  
A.D. Metcalfe ◽  
A. Gilmore ◽  
T. Klinowska ◽  
J. Oliver ◽  
A.J. Valentijn ◽  
...  
Keyword(s):  
Cell Death ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
De Novo ◽  
Mammary Epithelial Cells ◽  
Expression Profiles ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Pregnancy And Lactation

Epithelial cells within the mammary gland undergo developmental programmes of proliferation and apoptosis during the pregnancy cycle. After weaning, secretory epithelial cells are removed by apoptosis. To determine whether members of the Bcl-2 gene family could be involved in regulating this process, we have examined whether changes in their expression occur during this developmental apoptotic program in vivo. Bax and Bcl-x were evenly expressed throughout development. However, expression of Bak and Bad was increased during late pregnancy and lactation, and the proteins were present during the time of maximal apoptotic involution. Thereafter, their levels declined. In contrast, Bcl-w was expressed in pregnancy and lactation but was downregulated at the onset of apoptosis. Bcl-2 was not detected in lactating or early involuting mammary gland. Thus, the pro-apoptotic proteins Bax, Bak and Bad, as well as the death-suppressors Bcl-x, Bcl-2 and Bcl-w, are synthesised in mouse mammary gland, and dynamic changes in the expression profiles of these proteins occurs during development. To determine if changes in Bak and Bcl-w expression could regulate mammary apoptosis, their effect on cultured mouse mammary epithelial cells was examined in transient transfection assays. Enforced expression of Bak induced rapid mammary apoptosis, which could be suppressed by coexpression of Bcl-w. In extracts of mammary tissue in vivo, Bak heterodimerized with Bcl-x whereas Bax associated with Bcl-w, but Bak/Bcl-w heterodimers were not detected. Thus, Bak and Bcl-w may regulate cell death through independent pathways. These results support a model in which mammary epithelial cells are primed for apoptosis during the transition from pregnancy to lactation by de novo expression of the death effectors Bak and Bad. It is suggested that these proteins are prevented from triggering apoptosis by anti-apoptotic Bcl-2 family proteins until involution, when the levels of Bcl-w decline. Our study provides evidence that regulated changes in the expression of cell death genes may contribute to the developmental control of mammary apoptosis.

scholarly journals Muramyl Dipeptide Synergizes with Staphylococcus aureus Lipoteichoic Acid To Recruit Neutrophils in the Mammary Gland and To Stimulate Mammary Epithelial Cells

2010 ◽  
Vol 17 (11) ◽  
pp. 1797-1809 ◽  
Author(s):  
Salim Bougarn ◽  
Patricia Cunha ◽  
Abdallah Harmache ◽  
Angélina Fromageau ◽  
Florence B. Gilbert ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Synergistic Effects ◽  
Muramyl Dipeptide ◽  
Lipoteichoic Acid ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Chemokine Production

ABSTRACT Staphylococcus aureus, a major pathogen for the mammary gland of dairy ruminants, elicits the recruitment of neutrophils into milk during mastitis, but the mechanisms are incompletely understood. We investigated the response of the bovine mammary gland to muramyl dipeptide (MDP), an elementary constituent of the bacterial peptidoglycan, alone or in combination with lipoteichoic acid (LTA), another staphylococcal microbial-associated molecular pattern (MAMP). MDP induced a prompt and marked influx of neutrophils in milk, and its combination with LTA elicited a more intense and prolonged influx than the responses to either stimulus alone. The concentrations of several chemoattractants for neutrophils (CXCL1, CXCL2, CXCL3, CXCL8, and C5a) increased in milk after challenge, and the highest increases followed challenge with the combination of MDP and LTA. MDP and LTA were also synergistic in inducing in vitro chemokine production by bovine mammary epithelial cells (bMEpC). Nucleotide-binding oligomerization domain 2 (NOD2), a major sensor of MDP, was expressed (mRNA) in bovine mammary tissue and by bMEpC in culture. The production of interleukin-8 (IL-8) following the stimulation of bMEpC by LTA and MDP was dependent on the activation of NF-κB. LTA-induced IL-8 production did not depend on platelet-activating factor receptor (PAFR), as the PAFR antagonist WEB2086 was without effect. In contrast, bMEpC and mammary tissue are known to express Toll-like receptor 2 (TLR2) and to respond to TLR2 agonists. Although the levels of expression of the inflammatory cytokines tumor necrosis factor alpha (TNF-α) and IL-1β were increased by LTA and MDP at the mRNA level, no protein could be detected in the bMEpC culture supernatant. The level of induction of IL-6 was low at both the mRNA and protein levels. These results indicate that MDP and LTA exert synergistic effects to induce neutrophilic inflammation in the mammary gland. These results also show that bMEpC could contribute to the inflammatory response by recognizing LTA and MDP and secreting chemokines but not proinflammatory cytokines. Overall, this study indicates that the TLR2 and NOD2 pathways could cooperate to trigger an innate immune response to S. aureus mastitis.

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