Moderate High Temperature Condition Induces the Lactation Capacity of Mammary Epithelial Cells Through Control of STAT3 and STAT5 Signaling
In lactating mammary glands, alveolar mammary epithelial cells (MECs) synthesize and secrete milk components. MECs also form less permeable tight junctions (TJs) to prevent the leakage of milk components. During lactation, MECs are exposed to temperature changes by metabolic heat production and air ambient temperature. In this study, we investigated whether temperature changes influence milk production ability and TJ barriers in MECs by using two lactating culture models. The results showed that 39 °C treatment activated milk production and enhanced the formation of less-permeable TJs. In contrast, 41 °C treatment caused adverse effects on the TJ barrier and cell viability, although the milk production ability of MECs was temporarily up-regulated. MECs cultured at 37 °C showed relatively low milk production ability and high proliferation activity. Furthermore, we investigated three kinds of transcription factors relating to lactogenesis, signal transducer and activator of transcription 5 (STAT5), STAT3 and glucocorticoid receptor (GR). STAT5 signaling was activated at 39 and 41 °C by an increase in total STAT5. However, long-term treatment led to a decrease in total STAT5. STAT3 signaling was inactivated by high temperature treatment through a decrease in total STAT3 and inhibited phosphorylation of STAT3. GR signaling was continuously activated regardless of temperature. These results indicate that a moderate high temperature condition at 39 °C induces a high lactation capacity of MECs through control of STAT5 and STAT3 signaling. In contrast, long-term exposure at 41 °C leads to a decline in milk production capacity by inactivation of STAT5 and a decrease in the total number of MECs.
KeywordsMammary epithelial cell Heat stress Milk production
We are deeply grateful to Prof. Fumio Nakamura, Laboratory of Animal By-Product Science, Research Faculty of Agriculture, Hokkaido University, for fine instruction on immunohistochemistry techniques and useful discussions.
K.K. conceived the study, participated in the research design and implementation of the study, analyzed and interpreted the data, and drafted the manuscript. T.S. and T.N. participated in the research design and implementation of the study. Y.T. and K.M. performed the experiments and analyzed the data. All authors read and approved the final manuscript.
Compliance with Ethical Standards
The authors declare no competing financial interests.
- 14.Stelwagen K, Farr VC, McFadden HA, Prosser CG, Davis SR. Time course of milk accumulation-induced opening of mammary tight junctions, and blood clearance of milk components. Am J Phys. 1997;273(1 Pt 2):R379–86.Google Scholar
- 22.Kobayashi K, Tsugami Y, Matsunaga K, Oyama S, Kuki C, Kumura H. Prolactin and glucocorticoid signaling induces lactation-specific tight junctions concurrent with beta-casein expression in mammary epithelial cells. Biochim Biophys Acta. 2016;1863(8):2006–16. https://doi.org/10.1016/j.bbamcr.2016.04.023.
- 24.Kobayashi K, Oyama S, Kuki C, Tsugami Y, Matsunaga K, Suzuki T, et al. Distinct roles of prolactin, epidermal growth factor, and glucocorticoids in beta-casein secretion pathway in lactating mammary epithelial cells. Mol Cell Endocrinol. 2017;440:16–24. https://doi.org/10.1016/j.mce.2016.11.006.CrossRefPubMedGoogle Scholar
- 27.Mohammad MA, Hadsell DL, Haymond MW. Gene regulation of UDP-galactose synthesis and transport: potential rate-limiting processes in initiation of milk production in humans. Am J Physiol Endocrinol Metab. 2012;303(3):E365–76. https://doi.org/10.1152/ajpendo.00175.2012.CrossRefPubMedPubMedCentralGoogle Scholar
- 37.Rhoads ML, Rhoads RP, VanBaale MJ, Collier RJ, Sanders SR, Weber WJ, et al. Effects of heat stress and plane of nutrition on lactating Holstein cows: I. Production, metabolism, and aspects of circulating somatotropin. J Dairy Sci. 2009;92(5):1986–97. https://doi.org/10.3168/jds.2008-1641.CrossRefPubMedGoogle Scholar
- 40.Kabotyanski EB, Huetter M, Xian W, Rijnkels M, Rosen JM. Integration of prolactin and glucocorticoid signaling at the beta-casein promoter and enhancer by ordered recruitment of specific transcription factors and chromatin modifiers. Mol Endocrinol. 2006;20(10):2355–68. https://doi.org/10.1210/me.2006-0160.CrossRefPubMedGoogle Scholar
- 41.Qian X, Zhao FQ. Interactions of the ubiquitous octamer-binding transcription factor-1 with both the signal transducer and activator of transcription 5 and the glucocorticoid receptor mediate prolactin and glucocorticoid-induced beta-casein gene expression in mammary epithelial cells. Int J Biochem Cell Biol. 2013;45(3):724–35. https://doi.org/10.1016/j.biocel.2013.01.001.CrossRefPubMedGoogle Scholar
- 45.Reichenstein M, Rauner G, Barash I. Conditional repression of STAT5 expression during lactation reveals its exclusive roles in mammary gland morphology, milk-protein gene expression, and neonate growth. Mol Reprod Dev. 2011;78(8):585–96. https://doi.org/10.1002/mrd.21345.CrossRefPubMedGoogle Scholar
- 46.Kapila N, Sharma A, Kishore A, Sodhi M, Tripathi PK, Mohanty AK, et al. Impact of heat stress on cellular and transcriptional adaptation of mammary epithelial cells in Riverine Buffalo (Bubalus Bubalis). PLoS One. 2016;11(9):e0157237. https://doi.org/10.1371/journal.pone.0157237.CrossRefPubMedPubMedCentralGoogle Scholar
- 54.Dokladny K, Ye D, Kennedy JC, Moseley PL, Ma TY. Cellular and molecular mechanisms of heat stress-induced up-regulation of occludin protein expression: regulatory role of heat shock factor-1. Am J Pathol. 2008;172(3):659–70. https://doi.org/10.2353/ajpath.2008.070522.CrossRefPubMedPubMedCentralGoogle Scholar
- 56.Krug SM, Amasheh S, Richter JF, Milatz S, Gunzel D, Westphal JK, et al. Tricellulin forms a barrier to macromolecules in tricellular tight junctions without affecting ion permeability. Mol Biol Cell. 2009;20(16):3713–24. https://doi.org/10.1091/mbc.E09-01-0080.CrossRefPubMedPubMedCentralGoogle Scholar
- 58.de Nadal E, Ammerer G, Posas F. Controlling gene expression in response to stress. Nat Rev Genet. 2011;12(12):833–45. https://doi.org/10.1038/nrg3055 nrg3055.
- 64.Perotti C, Liu R, Parusel CT, Bocher N, Schultz J, Bork P, et al. Heat shock protein-90-alpha, a prolactin-STAT5 target gene identified in breast cancer cells, is involved in apoptosis regulation. Breast Cancer Res. 2008;10(6):R94. https://doi.org/10.1186/bcr2193.CrossRefPubMedPubMedCentralGoogle Scholar
- 70.Martinez-Rendon J, Sanchez-Guzman E, Rueda A, Gonzalez J, Gulias-Canizo R, Aquino-Jarquin G, et al. TRPV4 regulates tight junctions and affects differentiation in a cell culture model of the corneal epithelium. J Cell Physiol. 2017;232(7):1794–807. https://doi.org/10.1002/jcp.25698.CrossRefPubMedGoogle Scholar