Effects of inositol 1,4,5-trisphosphate on calcium release from the endoplasmic reticulum and golgi apparatus in mouse mammary epithelial cells: A comparison during pregnancy and lactation

In lactating mammary epithelial cells, interaction between caseins is believed to occur after their transport out of the endoplasmic reticulum. We show here that, in alpha(S1)-casein-deficient goats, the rate of transport of the other caseins to the Golgi apparatus is highly reduced whereas secretion of whey proteins is not significantly affected. This leads to accumulation of immature caseins in distended rough endoplasmic reticulum cisternae. Casein micelles, nevertheless, were still observed in secretory vesicles. In contrast, no accumulation was found in mammary epithelial cells which lack beta-casein. In mammary epithelial cells secreting an intermediate amount of alpha(S1)-casein, less casein accumulated in the rough endoplasmic reticulum, and the transport of alpha(S1)-casein to the Golgi occurred with kinetics similar to that of control cells. In prolactin-treated mouse mammary epithelial HC11 cells, which do not express alpha(S)-caseins, endoplasmic reticulum accumulation of beta-casein was also observed. The amount of several endoplasmic reticulum-resident proteins increased in conjunction with casein accumulation. Finally, the permeabilization of rough endoplasmic reticulum vesicles allowed the recovery of the accumulated caseins in soluble form. We conclude that optimal export of the caseins out of the endoplasmic reticulum is dependent upon alpha(S1)-casein. Our data suggest that alpha(S1)-casein interacts with the other caseins in the rough endoplasmic reticulum and that the formation of this complex is required for their efficient export to the Golgi.

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Orai calcium release-activated calcium modulator 1 (ORAI1) plays a role in endoplasmic reticulum stress in bovine mammary epithelial cells challenged with physiological levels of ketone bodies

Journal of Dairy Science ◽

10.3168/jds.2019-17422 ◽

2020 ◽

Vol 103 (5) ◽

pp. 4691-4701

Author(s):

Bingbing Zhang ◽

Ming Li ◽

Wei Yang ◽

Juan J. Loor ◽

Shuang Wang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Epithelial Cells ◽

Endoplasmic Reticulum Stress ◽

Calcium Release ◽

Mammary Epithelial Cells ◽

Ketone Bodies ◽

Mammary Epithelial ◽

Bovine Mammary Epithelial Cells

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Detection and regulation of leptin receptor mRNA in ovine mammary epithelial cells during pregnancy and lactation

FEBS Letters ◽

10.1016/s0014-5793(99)01616-6 ◽

1999 ◽

Vol 463 (1-2) ◽

pp. 194-198 ◽

Cited By ~ 61

Author(s):

Karine Laud ◽

Isabelle Gourdou ◽

Lucette Bélair ◽

Duane H. Keisler ◽

Jean Djiane

Keyword(s):

Epithelial Cells ◽

Leptin Receptor ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Receptor Mrna ◽

Pregnancy And Lactation

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

Journal of Cell Science ◽

10.1242/jcs.112.11.1771 ◽

1999 ◽

Vol 112 (11) ◽

pp. 1771-1783 ◽

Cited By ~ 6

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.

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Defects of the endoplasmic reticulum and changes to lipid droplet size in mammary epithelial cells due to miR-30b-5p overexpression are correlated to a reduction in Atlastin 2 expression

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2019.03.022 ◽

2019 ◽

Vol 512 (2) ◽

pp. 283-288 ◽

Cited By ~ 3

Author(s):

Sandrine Le Guillou ◽

Johann Laubier ◽

Christine Péchoux ◽

Etienne Aujean ◽

Johan Castille ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Epithelial Cells ◽

Droplet Size ◽

Lipid Droplet ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Lipid Droplet Size

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Expression of Prolactin mRNA in Rat Mammary Gland During Pregnancy and Lactation

Journal of Histochemistry & Cytochemistry ◽

10.1177/002215540004800308 ◽

2000 ◽

Vol 48 (3) ◽

pp. 389-395 ◽

Cited By ~ 13

Author(s):

Toshiki Iwasaka ◽

Shinobu Umemura ◽

Kochi Kakimoto ◽

Haruko Koizumi ◽

Yoshiyuki R. Osamura

Keyword(s):

Mammary Gland ◽

Epithelial Cells ◽

Mammary Epithelial Cells ◽

Late Pregnancy ◽

Mammary Epithelial ◽

Rt Pcr ◽

Pregnancy And Lactation ◽

Rat Mammary Gland ◽

Pcr Method

We studied the expression of prolactin (PRL) mRNA in the mammary gland of resting, pregnant, lactating, and weanling rats using in situ and solution reverse transcriptase-polymerase chain reaction (RT-PCR). In mid- to late pregnancy and throughout lactation, PRL mRNA was detected in both in situ and solution RT-PCR. These PRL mRNA signals were clearly identified in the cytoplasm of alveolar and ductal mammary epithelial cells by the in situ RT-PCR method. In mid- to late pregnancy, such as at the initiating point of PRL mRNA expression, we confirmed in some cases a lack of PRL mRNA by solution RT-PCR. In addition, in the early weaning phase, no signals were detected by solution RT-PCR. However, slight focal signals were detected in some poorly vacuolated cytoplasm of regressing acinar cells by in situ RT-PCR. These findings suggest that PRL mRNA in rat mammary gland begins in mid- to late pregnancy in parallel with the development of the mammary gland, continues throughout lactation, and declines in the early phase of weaning, with regression of mammary epithelial cells.

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RagD regulates amino acid mediated-casein synthesis and cell proliferation via mTOR signalling in cow mammary epithelial cells

Journal of Dairy Research ◽

10.1017/s0022029918000146 ◽

2018 ◽

Vol 85 (2) ◽

pp. 204-211 ◽

Cited By ~ 2

Author(s):

Ying Mu ◽

Dongmei Zheng ◽

Cong Wang ◽

Wei Yu ◽

Xiaonan Zhang

Keyword(s):

Cell Proliferation ◽

Amino Acid ◽

Epithelial Cells ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Mammary Tissue ◽

Lactation Period ◽

Mtor Inhibition ◽

Pregnancy And Lactation ◽

Casein Synthesis

This research paper addresses the hypothesis that RagD is a key signalling factor that regulates amino acid (AA) mediated-casein synthesis and cell proliferation in cow mammary epithelial cells (CMECs). The expression of RagD was analysed at different times during pregnancy and lactation in bovine mammary tissue from dairy cows. We showed that expression of RagD at lactation period was higher (P < 0·05) than that at pregnancy period. When CMECs were treated with methionine (Met) or lysine (Lys), expression of RagD, β-casein (CSN2), mTOR and p-mTOR, and cell proliferation were increased. Further, when CMECs were treated to overexpress RagD, expression of CSN2, mTOR and p-mTOR, and cell proliferation were up-regulated. Furthermore, the increase in expression of CSN2, mTOR and p-mTOR, and cell proliferation in response to Met or Lys supply was inhibited by inhibiting RagD, and those effects were reversed in the overexpression model. When CMECs were treated with RagD overexpression together with mTOR inhibition or conversely with RagD inhibition together with mTOR overexpression, results showed that the increase in expression of CSN2 and cell proliferation in response to RagD overexpression was prevented by inhibiting mTOR, and those effects were reversed by overexpressing mTOR. The interaction of RagD with subunit proteins of mTORC1 was analysed, and the result showed that RagD interacted with Raptor. CMECs were treated with Raptor inhibition, and the result showed that the increase in expression of mTOR and p-mTOR in response to RagD overexpression was inhibited by inhibiting Raptor.In conclusion, our study showed that RagD is an important activation factor of mTORC1 in CMECs, activating AA-mediated casein synthesis and cell proliferation, potentially acting via Raptor.

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Alterations in the Golgi Apparatus of the Breast Gland of the Rat During Pregnancy, Lactation, and Involution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066887 ◽

1971 ◽

Vol 29 ◽

pp. 566-567

Author(s):

Tariq M. Murad

Keyword(s):

Endoplasmic Reticulum ◽

Mammary Gland ◽

Epithelial Cells ◽

Golgi Apparatus ◽

Rough Surface ◽

Functional State ◽

Secretory Activity ◽

Pregnant Rats ◽

Pregnancy And Lactation ◽

Breast Gland

The mammary gland proliferates and differentiates into its functional state under the influence of various hormones secreted during pregnancy and lactation. Lipid, protein, and carbohydrates, which are important constituents of milk, are known to be secreted by this gland. These substances are synthesized and secreted by the mammary gland in varying concentrations during the gestation and lactation periods. The Golgi apparatus is known to play an important role in the secretory activity of the cells. It is the site of the formation of glycoprotein on the rough surface of the endoplasmic reticulum. In a previous study we were able to show the formation of two types of proteins formed in the epithelial cells of the mammary ductules of pregnant rats that were secreted into the lumina before parturition. The Golgi apparatus played no part in the formation of these particles.

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