Both cell substratum regulation and hormonal regulation of milk protein gene expression are exerted primarily at the posttranscriptional level

1988 ◽  
Vol 8 (8) ◽  
pp. 3183-3190
Author(s):  
R S Eisenstein ◽  
J M Rosen
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Protein Gene ◽  
Fold Increase ◽  
Collagen Gels ◽  
Mrna Accumulation ◽  
Milk Protein Gene ◽  
Casein Gene ◽  
Beta Casein ◽  
D Cells

The mechanism by which individual peptide and steroid hormones and cell-substratum interactions regulate milk protein gene expression has been studied in the COMMA-D mammary epithelial cell line. In the presence of insulin, hydrocortisone, and prolactin, growth of COMMA-D cells on floating collagen gels in comparison with that on a plastic substratum resulted in a 2.5- to 3-fold increase in the relative rate of beta-casein gene transcription but a 37-fold increase in beta-casein mRNA accumulation. In contrast, whey acidic protein gene transcription was constitutive in COMMA-D cells grown on either substratum, but its mRNA was unstable and little intact mature mRNA was detected. Culturing COMMA-D cells on collagen also promoted increased expression of other genes expressed in differentiated mammary epithelial cells, including those encoding alpha- and gamma-casein, transferrin, malic enzyme, and phosphoenolpyruvate carboxykinase but decreased the expression of actin and histone genes. Using COMMA-D cells, we defined further the role of individual hormones in influencing beta-casein gene transcription. With insulin alone, a basal level of beta-casein gene transcription was detected in COMMA-D cells grown on floating collagen gels. Addition of prolactin but not hydrocortisone resulted in a 2.5- to 3.0-fold increase in beta-casein gene transcription, but both hormones were required to elicit the maximal 73-fold induction in mRNA accumulation. This posttranscriptional effect of hormones on casein mRNA accumulation preceded any detectable changes in the relative rate of transcription. Thus, regulation by both hormones and cell substratum of casein gene expression is exerted primarily at the post transcriptional level.

scholarly journals Both cell substratum regulation and hormonal regulation of milk protein gene expression are exerted primarily at the posttranscriptional level.

1988 ◽  
Vol 8 (8) ◽  
pp. 3183-3190 ◽  
Author(s):  
R S Eisenstein ◽  
J M Rosen
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Protein Gene ◽  
Fold Increase ◽  
Collagen Gels ◽  
Mrna Accumulation ◽  
Milk Protein Gene ◽  
Casein Gene ◽  
Beta Casein ◽  
D Cells

The mechanism by which individual peptide and steroid hormones and cell-substratum interactions regulate milk protein gene expression has been studied in the COMMA-D mammary epithelial cell line. In the presence of insulin, hydrocortisone, and prolactin, growth of COMMA-D cells on floating collagen gels in comparison with that on a plastic substratum resulted in a 2.5- to 3-fold increase in the relative rate of beta-casein gene transcription but a 37-fold increase in beta-casein mRNA accumulation. In contrast, whey acidic protein gene transcription was constitutive in COMMA-D cells grown on either substratum, but its mRNA was unstable and little intact mature mRNA was detected. Culturing COMMA-D cells on collagen also promoted increased expression of other genes expressed in differentiated mammary epithelial cells, including those encoding alpha- and gamma-casein, transferrin, malic enzyme, and phosphoenolpyruvate carboxykinase but decreased the expression of actin and histone genes. Using COMMA-D cells, we defined further the role of individual hormones in influencing beta-casein gene transcription. With insulin alone, a basal level of beta-casein gene transcription was detected in COMMA-D cells grown on floating collagen gels. Addition of prolactin but not hydrocortisone resulted in a 2.5- to 3.0-fold increase in beta-casein gene transcription, but both hormones were required to elicit the maximal 73-fold induction in mRNA accumulation. This posttranscriptional effect of hormones on casein mRNA accumulation preceded any detectable changes in the relative rate of transcription. Thus, regulation by both hormones and cell substratum of casein gene expression is exerted primarily at the post transcriptional level.

scholarly journals Targeted c-myc gene expression in mammary glands of transgenic mice induces mammary tumours with constitutive milk protein gene transcription.

1988 ◽  
Vol 7 (1) ◽  
pp. 169-175 ◽  
Author(s):  
C. A. Schoenenberger ◽  
A. C. Andres ◽  
B. Groner ◽  
M. van der Valk ◽  
M. LeMeur ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Gene Transcription ◽  
Milk Protein ◽  
Protein Gene ◽  
Mammary Glands ◽  
Milk Protein Gene ◽  
Mammary Tumours ◽  
Myc Gene

scholarly journals Cell proliferation and milk protein gene expression in rabbit mammary cell cultures

1983 ◽  
Vol 96 (5) ◽  
pp. 1435-1442 ◽  
Author(s):  
YML Suard ◽  
M Haeuptle ◽  
E Farinon ◽  
J Kraehenbuhl
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Protein Synthesis ◽  
Milk Protein ◽  
Protein Gene ◽  
Milk Proteins ◽  
Collagen Gels ◽  
Milk Protein Gene ◽  
Milk Protein Genes ◽  
Milk Protein Gene Expression

We analyzed the synthesis of DNA, the rate of cell proliferation, and the expression of milk protein genes in mammary cells grown as primary cultures on or in collagen gels in chemically defined media. We assessed DNA synthesis and cell growth, measured by [(3) H]- thymidine incorporation into acid-insoluble material, DNA content, and cell counts, in a progesterone- and prolactin-containing medium. In some experiments, cultures were pulsed for 1 h with [(3)H]thymidine and dissociated into individual cells which were cytocentrifuged and processed for immunocytochemistry and autoradiography. We analyzed expression of milk protein genes at the transcriptional, translation and posttranslational levels in progesterone-depleted medium in the presence or absence of prolactin. We measured protein secretion by radioimmunoassays with antisera directed against caseins, α-lactalbumin and milk transferrin1. We determined protein synthesis by incorporating radio-labeled amino acids into acid-precipitable material and by immunoprecipitating biosynthetically labeled milk proteins. We assessed the accumulation of casein mRNA by hybridizing total cellular RNA extracted from cultured cells with (32)P-labeled casein cDNA probes. On attached collagen gels, the cells synthesized DNA and replicated until they became confluent. The overall protein synthetic activity was low, and no milk proteins were synthesized or secreted even in the presence of prolactin. The block in milk protein gene expression was not restricted to translational or posttranslational events but also included transcription, since no casein mRNA accumulated in these cells. On floating gels, protein synthesis was threefold higher than in cells from attached gels. Overall protein synthesis as well as casein and α-lactalbumin synthesis and secretion were prolactin-dependent with maximal stimulation at around 10(-9) M. A marked inhibition occurred at higher hormone concentrations. Casein mRNA accumulated in these cells, provided prolactin was present in the medium. In contrast, these cells did not synthesize DNA, nor did they replicate. In embedding gels, the rate of cell proliferation was exponential over 25 d with a doubling time of approximately 70 h. The overall protein synthesis increase was parallel in time with the increase in cell number. Caseins and α-lactalbumin (in contrast to transferrin) were synthesized only in the presence of prolactin. We observed the same hormone dependency as with cells growing on floating gels. The number of casein- and transferring-positive cells was measured after dissociating the cell cultures. At day 12, 60 percent of the total cells stored transferring in small cytoplasmic vesicles, whereas only 25 percent of the cells accumulated casein. Differences in the organization and in the shape of mammary cells depending on cell surface conditions suggest that the geometry of the cells, their interaction with extracellular matrix constituents, and cell-to-cell interactions play a role in the expression of two mammary functions: DNA synthesis and growth, as well as milk protein gene expression.

Hormone-dependent milk protein gene expression in bovine mammary explants from biopsies at different stages of pregnancy

2004 ◽  
Vol 71 (2) ◽  
pp. 135-140 ◽  
Author(s):  
Paul A Sheehy ◽  
James J Della-Vedova ◽  
Kevin R Nicholas ◽  
Peter C Wynn
Keyword(s):  
Gene Expression ◽  
Milk Protein ◽  
Protein Gene ◽  
Bovine Milk ◽  
Mammary Tissue ◽  
Endocrine Regulation ◽  
Surgical Biopsy ◽  
Milk Protein Gene ◽  
Milk Protein Gene Expression

A method for the collection of mammary biopsies developed previously was refined and used to study the endocrine regulation of bovine milk protein gene expression. Our surgical biopsy method used real-time ultrasound imaging and epidural analgesia to enable recovery of a sufficient quantity of mammary tissue from late-pregnant dairy cows for explant culture in vitro. The time of biopsy was critical for prolactin-dependent induction of milk protein gene expression in mammary explants, as only mammary tissue from cows nearing 30 d prepartum was hormone-responsive. This suggests that during the later stages of pregnancy a change in the responsiveness of milk protein gene expression to endocrine stimuli occurred in preparation for lactation. This may relate to the diminution of a putative population of undifferentiated cells that were still responsive to prolactin. Alternatively, the metabolic activity of the tissue had increased to the level whereby the response of the tissue was no longer assessable using this model in vitro.

Effects of compensatory growth on milk protein gene expression and mammary differentiation

1988 ◽  
Vol 2 (10) ◽  
pp. 2619-2624 ◽  
Author(s):  
Chung S. Park ◽  
Yun J. Choi ◽  
Wanda L. Keller ◽  
Robert L. Harrold
Keyword(s):  
Gene Expression ◽  
Compensatory Growth ◽  
Milk Protein ◽  
Protein Gene ◽  
Milk Protein Gene ◽  
Milk Protein Gene Expression

scholarly journals  Gene expression of six major milk proteins in primary bovine mammary epithelial cells isolated from milk during the first twenty weeks of lactation

2012 ◽  
Vol 57 (No. 10) ◽  
pp. 469-480 ◽  
Author(s):  
T. Sigl ◽  
H.H.D. Meyer ◽  
S. Wiedemann
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Milk Protein ◽  
Protein Gene ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Milk Protein Gene ◽  
Bovine Mammary Epithelial Cells ◽  
Milk Protein Genes ◽  
Milk Protein Gene Expression

&nbsp;The objective of the present study was to refine a previously developed method to isolate primary bovine mammary epithelial cells (pBMEC) from fresh milk. Using this method, it was tested whether the number of pBMEC and the relation of recovered pBMEC to total somatic cell count vary within the individual lactation stages. Furthermore, the expression levels of the milk protein genes during the first twenty weeks of lactation were determined by quantitative PCR method. A total number of 152 morning milk samples were obtained from twenty-four Holstein-Friesian cows during the first 20 weeks of lactation (day 8, 15, 26, 43, 57, 113, and 141 postpartum). Numbers of extracted pBMEC were consistent at all time-points (1.1 &plusmn; 0.06 to 1.4 &plusmn; 0.03 &times;10<sup>3</sup>/ml) and an average value of RNA integrity number (RIN) was 6.3 &plusmn; 0.3. Percentage of pBMEC in relation to total milk cells (2.0 &plusmn; 0.2 to 6.7 &plusmn; 1.0%) correlated with milk yield. Expression patterns of the casein genes alpha (&alpha;)<sub>S1</sub>, (&alpha;)<sub>S2</sub>, beta (&beta;), and kappa (&kappa;) (CSN1S1, CSN1S2, CSN2, CSN3, respectively) and the whey protein genes &alpha;-lactalbumin (LALBA) and progestagen-associated endometrial protein (PAEP; known as &beta;-lactoglobulin) were shown to be comparable, i.e. transcripts of all six milk protein genes were found to peak during the first two weeks of lactation and to decline continuously towards mid lactation. However, mRNA levels were different among genes with CSN3 showing the highest and LALBA the lowest abundance. We hypothesized that milk protein gene expression has a pivotal effect on milk protein composition with no influence on milk protein concentration. This paper is the first to describe milk protein gene expression during lactation in pBMEC collected in milk. Future studies will be needed to understand molecular mechanisms in pBMEC including regulation of expression and translation throughout lactation. &nbsp;

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