scholarly journals Differential expression of α-lactalbumin and casein genes during the onset of lactation in the guinea-pig mammary gland

1981 ◽  
Vol 194 (3) ◽  
pp. 999-1006 ◽  
Author(s):  
L J Burditt ◽  
D Parker ◽  
R K Craig ◽  
T Getova ◽  
P N Campbell
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Post Partum ◽  
Mammary Tissue ◽  
Milk Protein Gene ◽  
Milk Protein Gene Expression ◽  
Gene Transcripts ◽  
Casein Genes ◽  
In Pregnancy ◽  
Alpha Lactalbumin

1. The expression of alpha-lactalbumin and casein genes was examined in guinea-pig mammary tissue taken from animals both pre- and post-partum. 2. Analysis of total RNA by RNA excess hybridization with sequence-specific complementary DNA probes demonstrated that alpha-lactalbumin mRNA was present late in pregnancy, and that maximum concentrations were present at parturition. Casein gene transcripts were absent late in pregnancy (62 days), but by parturition were present at concentrations identical to those found at all time points examined throughout lactation. 3. Studies using mammary explants in organ culture showed that tissue from pregnant animals, or animals at parturition, synthesized and secreted only alpha-lactalbumin. After parturition, at the onset of casein synthesis, differential rates of secretion of alpha-lactalbumin and the caseins were observed. 4. The results are discussed in terms of the multiple intracellular mechanisms involved in the regulation of milk protein gene expression in the guinea-pig mammary gland.

scholarly journals Transgenic mice carrying the guinea-pig α-lactalbumin gene transcribe milk protein genes in their sebaceous glands during lactation

1991 ◽  
Vol 275 (2) ◽  
pp. 459-467 ◽  
Author(s):  
A Maschio ◽  
P M Brickell ◽  
D Kioussis ◽  
A L Mellor ◽  
D Katz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Guinea Pig ◽  
Milk Protein ◽  
Mouse Skin ◽  
Sebaceous Glands ◽  
Milk Protein Gene ◽  
Milk Protein Genes ◽  
Milk Protein Gene Expression ◽  
Alpha Lactalbumin

We have generated transgenic mice carrying the entire guinea-pig alpha-lactalbumin gene. Lactating transgenic mice expressed high levels of correctly initiated and processed guinea-pig alpha-lactalbumin mRNA in the secretory epithelium of their mammary glands, and secreted guinea-pig alpha-lactalbumin in their milk. Transcripts were detectable after 7 days of pregnancy, indicating that the transgene was under correct hormonal control. Whereas no or negligible transcription was detectable in all other tissues tested, high levels of transcripts were found in the skin of lactating transgenic mice. Guinea-pig alpha-lactalbumin protein was undetectable in the skin, however. In situ hybridization analysis showed that expression was localized to the undifferentiated cells in the basal layer of the sebaceous glands. Further studies revealed high levels of endogenous beta-casein mRNA in normal lactating mouse skin, demonstrating that the transcription of milk protein genes in lactating mouse skin is a normal event, and is not peculiar to the transgene. This surprising finding highlights the developmental relationship of the mammary gland to other specialized structures of the skin, supports a role for epithelial-extracellular matrix interactions in the regulation of milk protein gene expression in vivo, and identifies the skin as a particularly accessible model system in which to study the regulation of milk protein gene expression. In addition, the guinea-pig alpha-lactalbumin gene will be a source of regulatory sequences with which to direct heterologous gene expression to the sebaceous glands of transgenic mice.

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.

scholarly journals Suppression of lactation and acceleration of involution in the bovine mammary gland by a selective serotonin reuptake inhibitor

2011 ◽  
Vol 209 (1) ◽  
pp. 45-54 ◽  
Author(s):  
L L Hernandez ◽  
J L Collier ◽  
A J Vomachka ◽  
R J Collier ◽  
N D Horseman
Keyword(s):  
Gene Expression ◽  
Mammary Gland ◽  
Milk Yield ◽  
Milk Protein ◽  
Protein Gene ◽  
Holstein Cows ◽  
Dependent Manner ◽  
Bovine Mammary Gland ◽  
Milk Protein Gene ◽  
Milk Protein Gene Expression

Serotonin (5-HT) is a homeostatic regulator of lactation. Selective 5-HT reuptake inhibitors (SSRI) are commonly prescribed pharmaceuticals that inhibit activity of the 5-HT reuptake transporter, increasing cellular exposure to 5-HT. Use of SSRIs has been shown to alter lactation performance in humans and 5-HT has been shown to reduce milk yield in cattle. However, it has not been determined how SSRI treatments affect the bovine mammary gland. We evaluated the effects of SSRI (fluoxetine (FLX)) administration on tight junctions (TJs) and milk protein gene expression in a lactogenic culture model, using primary bovine mammary epithelial cells (pBMEC). Additionally, we evaluated the effects of intramammary infusions of FLX and 5-hydroxytryptophan on milk production and TJ status in multiparous Holstein cows at dry-off. Treatment of pBMEC cultured on permeable membranes disrupted TJs, as measured by transepithelial resistance and immunostaining for zona occludens 1. Correspondingly, treatment of ‘3D’, collagen-embedded lactogenic cultures of pBMEC with FLX suppressed milk protein gene expression (α-lactalbumin and β-casein) in a concentration-dependent manner. Finally, intramammary treatment of Holstein cows with FLX resulted in an accelerated rate of milk decline. Additionally, TJ permeability increased in FLX-treated animals, as measured by plasma lactose and milk Na+ and K+ levels. Results of these experiments imply that SSRI administration accelerates the rate of mammary gland involution through disassembly of TJs and inhibition of milk protein gene expression in vitro and in vivo, leading to reduction of milk yield.

scholarly journals Cellular localisation of GH receptor in the bovine mammary gland during mammogenesis, lactation and involution

2000 ◽  
Vol 166 (3) ◽  
pp. 503-510 ◽  
Author(s):  
F Sinowatz ◽  
D Schams ◽  
S Kolle ◽  
A Plath ◽  
D Lincoln ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Post Partum ◽  
In Situ Hybridisation ◽  
Alveolar Epithelium ◽  
Mammary Tissue ◽  
Bovine Mammary Gland ◽  
Direct Role ◽  
Gh Receptor ◽  
Gh Receptors

We have used immunohistochemistry and non-radioactive in situ hybridisation to localise the GH receptor and its transcript in the bovine mammary gland during mammogenesis, lactation and involution. We found a characteristic pattern of immunoreactive GH (irGH) receptor distribution in the epithelial and stromal compartments during the different stages of mammary gland development: The ductular epithelium showed a distinct staining for irGH receptor during most stages, whereas the alveolar epithelium contained a modest amount of GH receptor during pregnancy which increased during lactation and galactopoiesis. In dry cows, the immunostaining for GH receptors in the alveolar epithelium was very weak or negative. Curiously, the amount of GH receptor mRNA appeared relatively constant during mammogenesis and lactation. The epithelial cells of the alveoli and ducts as well as the endothelial cells showed a distinct signal in our in situ hy! bridisation studies. The predominant localisation of GH receptors in the epithelium of ducts and alveoli is supportive of a role for GH in epithelial differentiation and maintenance. Furthermore, the increased intensity of immunostaining in bovine mammary tissue post partum suggests a direct role for GH receptor in mediating the effect of GH in milk production and secretion.

scholarly journals The Role of Glucocorticoids in Pregnancy, Parturition, Lactation, and Nurturing in Melanocortin Receptor 2-Deficient Mice

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1652-1660 ◽  
Author(s):  
Dai Chida ◽  
Keiko Miyoshi ◽  
Tsuyoshi Sato ◽  
Tetsuya Yoda ◽  
Takefumi Kikusui ◽  
...  
Keyword(s):  
Mammary Epithelium ◽  
Milk Proteins ◽  
Myoepithelial Cells ◽  
Melanocortin Receptor ◽  
Milk Protein Gene ◽  
Fetal Survival ◽  
Pup Retrieval ◽  
Milk Protein Gene Expression ◽  
In Pregnancy

Abstract Maternal glucocorticoids are critical for fetal development, but overexpression can be deleterious. Previously we established a mouse line deficient in melanocortin receptor 2 (MC2R). MC2R−/− mice have undetectable levels of corticosterone despite high levels of ACTH and defects resembling those in patients with familial glucocorticoid deficiency. Here we analyzed the role of glucocorticoids in pregnancy, parturition, lactation, and nurturing in MC2R−/− mice. MC2R−/− mice were fertile and produced normal litters when crossed with MC2R+/+ mice. However, MC2R−/− females crossed with MC2R−/− males had no live births, and approximately 20% of the embryos at d 18.5 of pregnancy were of normal body size but were dead when born. MC2R−/− pregnant females crossed with MC2R+/+ males had detectable serum corticosterone levels, suggesting the transplacental passage of corticosterone from fetus to mother. MC2R+/− pups delivered from MC2R−/− females crossed with MC2R+/+ males mice thrived poorly with MC2R−/− mothers but grew to adulthood when transferred to foster mothers after birth, suggesting that MC2R−/− females are poor mothers or cannot nurse. MC2R−/− females had normal alveoli, but penetration of mammary epithelium into fat pads and expression of milk proteins were reduced. Myoepithelial cells, which force milk out of the alveoli, were fully developed and differentiated. Pup retrieval behavior was normal in MC2R−/− mice. Exogenous corticosterone rescued expression of milk proteins in MC2R−/− mothers, and the pups of treated mothers grew to adulthood. Our results reveal the importance of glucocorticoids for fetal survival late in pregnancy, mammary gland development, and milk protein gene expression.

Progressive changes in milk protein gene expression and prolactin binding during lactation in the tammar wallaby (Macropus eugenii)

1994 ◽  
Vol 13 (2) ◽  
pp. 117-125 ◽  
Author(s):  
P H Bird ◽  
K A K Hendry ◽  
D C Shaw ◽  
C J Wilde ◽  
K R Nicholas
Keyword(s):  
Gene Expression ◽  
Milk Protein ◽  
Protein Gene ◽  
Tammar Wallaby ◽  
Mammary Tissue ◽  
Phase 2 ◽  
Phase 3 ◽  
Milk Protein Gene ◽  
Macropus Eugenii ◽  
Milk Protein Gene Expression

ABSTRACT Changes in milk protein gene expression and specific prolactin binding were quantified in mammary tissue from the tammar wallaby (Macropus eugenii) at different stages of lactation. The transition from early (phase 2) lactation to late (phase 3) lactation was characterized by the induction of the gene for late lactation protein, a novel whey protein. During the same period, the levels of β-lactoglobulin and β-casein gene expression increased, whereas there was no change in the levels of expression of α-lactalbumin and α-casein genes. Prolactin binding in the mammary gland doubled during the latter half of phase 2 of lactation but declined significantly during the transition to phase 3 of lactation. These changes in prolactin binding resulted from changes in the number of receptors and not from a change in the affinity of the receptor for prolactin. Treatment of membranes with concanavalin A increased the number of prolactin-binding sites by 40% in membranes from phase 2 mammary tissue but decreased binding by 40% in membranes from phase 3 tissue, indicating that significant changes had occurred in the membranes of cells during this period. The tammar wallaby can secrete phase 2 and phase 3 milk from adjacent mammary glands (asynchronous concurrent lactation) and the developmental changes in milk protein gene expression and prolactin binding observed during lactation were reflected in these individual glands. Taken collectively, these findings suggest that mammary development and milk secretion in the tammar wallaby are regulated by both endocrine and local (intramammary) mechanisms.

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation

1992 ◽  
Vol 263 (6) ◽  
pp. E1077-E1085 ◽  
Author(s):  
M. Rakopoulos ◽  
S. J. Vargas ◽  
M. T. Gillespie ◽  
P. W. Ho ◽  
H. Diefenbach-Jagger ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Parathyroid Hormone ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Related Protein ◽  
Sprague Dawley ◽  
Parathyroid Hormone Related Protein ◽  
Pregnancy And Lactation ◽  
Rat Mammary Gland ◽  
In Pregnancy

Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E1077-E1085, 1992.--Production of parathyroid hormone-related protein (PTHrP) by the mammary gland of Sprague-Dawley rats has been examined using immunohistochemistry and in situ hybridization to detect PTHrP and PTHrP mRNA, respectively. PTHrP and PTHrP mRNA could be demonstrated in nests of epithelial cells of the developing mammary gland at day 14 of pregnancy and in the epithelial secretory cells lining the alveoli during the latter stages of pregnancy and during lactation. A specific radioimmunoassay was also used to measure the concentration of PTHrP secreted in the milk throughout lactation. The concentration of PTHrP in milk was relatively low initially but increased during the latter stages of lactation, whereas calcium concentrations remained virtually constant throughout lactation. No correlation was found between the concentrations of calcium and PTHrP in rat milk. These results show that PTHrP is present in rat milk and also in mammary tissue before parturition, and therefore it may assist in the development of the mammary gland during pregnancy.

scholarly journals Guinea-pig milk-protein synthesis. Isolation and characterization of messenger ribonucleic acids from lactating mammary gland and identification of caseins and pre-α-lactalbumin as translation products in heterologous cell-free systems

1976 ◽  
Vol 160 (1) ◽  
pp. 57-74 ◽  
Author(s):  
R K Craig ◽  
P A Brown ◽  
O S Harrison ◽  
D McIlreavy ◽  
P N Campbell
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Guinea Pig ◽  
Wheat Germ ◽  
Milk Proteins ◽  
N Terminus ◽  
Lactating Mammary Gland ◽  
Heterologous Cell ◽  
Alpha Lactalbumin

1. The major milk proteins synthesized by the lactating mammary gland of the guinea pig were identified and designated as caseins A, B and C and alpha-lactalbumin, with estimated mol.wts. of 28000, 25500, 20500 and 14500 respectively. 2. Antisera to the total casein fraction and to alpha-lactalbumin were prepared from rabbits. The milk proteins were also iodinated with either 131I or 125I. 3. A poly(A)-rich RNA fraction was isolated from lactating guinea-pig mammary glands. Isolation was by affinity chromatography on oligo(dT)-cellulose. 4. Examination of this RNA fraction by electrophoresis on polyacrylamide gels containing formamide indicated three major species 1, 2 and 3, with estimated wol.wts. of 5.4 × 10(5) and 3.3 × 10(5), and the apparent absence of rRNA species. 5. The poly(A)-rich RNA stimulated protein synthesis in heterologous cell-free systems based on wheat germ, Krebs II ascites-tumour cells, and the latter supplemented with an initiation factor-3 fraction from rabbit reticulocyte ribosomes. 6. Between 80 and 90% of the protein synthesis directed by the mRNA was for milk proteins. 7. Analysis of the proteins immunoprecipitated by the alpha-lactalbumin antiserum showed in the wheat-germ system that the product was a protein with a molecular weight greater than that of alpha-lactalbumin, whereas in the ascites-tumour-cell systems both this protein and alpha-lactalbumin were found. When the larger protein was treated with CNBr and the resulting peptides were examined, it was shown that the extra peptide was at the N-terminus. This and other evidence is adduced for the initial translation product of alpha-lactalbumin being a precursor with an addition of about ten amino acids at the N-terminus. 8. Similar analysis of the casein immlnospecific proteins produced under the direction of mRNA indicated that the products had a molecular weight that was apparently a littel smaller than that of the caseins synthesized in vivo. This was not consistent with higher-molecular weight casein precursors. 9. Possible explanations for the results obtained are discussed, especially in terms of the physiological significance of the pre-alpha-lactalbumin as a secretory protein.

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