Integrin Alpha6and Beta4Mediated Laminin And Regulated Mammary Epithelial Cells

The interactions between cell-cell and cell-extracellular matrix (ECM) were mediated by integrin—an important cell adhesion molecules which play a role in receptor-ligand bingding. The development and function of epithelial tissue need to intergrate the signal from local cellular microenvironment and long range hormones. Cells adhering to ECM is the most important in different types of local signals determing cell fate. Integrin is a major cell surface receptor adhering cell to ECM, cell shape was organized by cytoskeleton, they also affect cell fate decisions. Integrin was involved in cell recognition and bingding, activation and signal transduction, involved in cell proliferation, survival, migration, differentiation, and cell extension and transger, it was the physiological basis of immune guide, inflammation, coagulation, tumor metastasis and wound healing in a series of physiological and pathological processes.The new view considered that the extracellular environment was controlled by integrin, thereby, enabiling the cells to have checkpoint of content-dependent growth factor and hormone signaling. However, the exception of the comprehensive understangding of the normal epithelial development and abnormality mechanisms is still an important challenge to faced by researchers, and it was required a cell-extracellular matrix interactions how to connected the biological effect of downstream, and analysis the regulation manner of the specific intermeidiate molecules. The purpose of this study is to reveal the relationship among integrin alpha6and integrin beta4mRNA level expression, protein level expression and mammary gland development and lactation, illuminate the molecular mechanism of between integrin alpha6and integrin beta4expression level and prolactin (PRL), growth hormone (GH), insulin-like growth factor-1(IGF-1) and insulin-linke growth factor-2(IGF-2) and laminin (LN). It will provide the basic data for the research of amimal mammary gland development and lactation mechanism, the feasible technologies and credible theoretical support for milk quality and milk production of the artificial regulation.In this study, the mammary gland of Holstein dairy cows were used as the experimental materials, applying fluorescence quantitative RT-PCR, western blotting techniques and immunofluorescence staining technology, the expression and localization of integrin alpha6and integrin beta4at different stages in dairy cows mammary gland tissue were detected. With dairy cow mammary epithelial cells of lactation culturing in vitro for model, the influence of LN played the role between integrin alpha6and integrin beta4, and the regulation of mammary epithelial cell proliferation and lactation performance of the crosstalk effect with PRL, GH, IGF-1and IGF-2 were determinedResults showed that integrin alpha6and integrin beta4expressed in the different development periods of dairy cow mammary gland, but expression were not consistent. Integrin alpha6is significantly up-regulated in the pregnancy (P<0.05), and the mid of pregnancy reached to the peak. Integrin beta4is significantly up-regulated in the virgin and pregnancy (P<0.05), and the mid of pregnancy reached to the peak. The results are similar to fluorescent quantitative RT-PCR. Though, the integrin alpha6is significantly up-regulated in telophase of pregnancy, and integrin beta4is significantly up-regulated in primary virgin. The levels of mRNA and protein expression of integrin alpha6and integrin beta4were positively correlated.Tissue explant technique successfully obtained dairy cow mammary epithelial cells. The expression level of integrin alpha6and integirn beta4were promoted by LN and different lactation honnones and cell factors, which of GH and IGF-1treated group are significantly up-regulated (P<0.05). Integrin beta4was significantly up-regulated by LN (P<0.05). Results showed that LN encouraged the expression of integrin alpha6and beta4, meanwhile, cell adhesion was induced. IGF-1and IGF-2encouraged cell adhesion. Integrin alpha6and integrin beta4involved in cell proliferation, while there was significantly encouraged cell proliferation with LN (P<0.05), but cell survival was encouraged by PRL and IGF-2that were detectd by MTT. After the lactose secretion and milk fat were detected demonstrate that integrin alpha6and integrin beta4played positive regulatory roles. PRL, GH, IGF-1and IGF-2were positive regulation of lactopretein, while LN was negative regulation of lactose.In summary, series of experiments with the interaction of cell-extracellular was designed in this study, alpha6and beta4subunit from integrin family and their ligands in dairy cows were validated—the regulation mechanism and the role of lactation by laminin. It provides a new research methods and ideas in the field of mammary gland development and the lactation regulation.