Kang Minkyung, Jeong Wooyoung, Bae Hyocheol, Lim Whasun, Bazer Fuller W, Song Gwonhwa
Institute of Animal Molecular Biotechnology and Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.
Department of Animal Resources Science, Dankook University, Cheonan, Republic of Korea.
J Cell Physiol. 2018 Mar;233(3):2560-2571. doi: 10.1002/jcp.26131. Epub 2017 Sep 11.
Structural and functional development of the mammary gland is constant in the mammary gland life cycle. Eph receptors and their ligands, ephrins, control events through cell-to-cell interactions during embryonic development, and adult tissue homeostasis; however, little information on participation of ephrin A1, a representative ligand of the Eph receptor, in the development and function of normal mammary glands is known. In this study, we demonstrated functional effects of the ephrin A1-Eph system and mechanisms of its action on bovine mammary epithelial (MAC-T) cells. The in vitro cultured MAC-T cells expressed the ephrin A1 ligand and EphA1, A2, A4, A7, and A8 among the eight members of the Eph A family. Our results revealed that ephrin A1 induced MAC-T cell cycle progression and stimulated cell proliferation with abundant expression of nucleic PCNA and cyclin D1 proteins. Additionally, ephrin A1 induced activation of intracellular signaling molecules involved in PI3 K/AKT and MAPK signaling, and the proliferation-stimulating effect of ephrin A1 was mediated by activation of these pathways. Furthermore, ephrin A1 influenced expression and activation of various ER stress-related proteins and protected MAC-T cells from stress-induced cell death. Finally, ephrin A1 alleviated LPS-induced cell death through down-regulation of inflammatory cytokines. In conclusion, the results of this study suggest that the Eph A-ephrin A1 system is a positive factor in the increase and maintenance of epithelial cells in mammary glands of cows; the signaling system contributes to development, remodeling, and functionality of normal mammary glands and could overcome mastitis in cows and other mammals.
乳腺的结构和功能发育在乳腺生命周期中是持续进行的。Eph受体及其配体（ Ephrin）在胚胎发育和成年组织稳态过程中通过细胞间相互作用控制各种事件；然而，关于Eph受体的代表性配体Ephrin A1在正常乳腺发育和功能中的参与情况，所知甚少。在本研究中，我们证明了Ephrin A1-Eph系统对牛乳腺上皮（MAC-T）细胞的功能作用及其作用机制。体外培养的MAC-T细胞表达Ephrin A1配体以及Eph A家族八个成员中的EphA1、A2、A4、A7和A8。我们的结果显示，Ephrin A1诱导MAC-T细胞周期进程，刺激细胞增殖，伴随核酸PCNA和细胞周期蛋白D1蛋白的大量表达。此外，Ephrin A1诱导参与PI3K/AKT和MAPK信号传导的细胞内信号分子激活，并且Ephrin A1的增殖刺激作用是由这些信号通路的激活介导的。此外，Ephrin A1影响各种内质网应激相关蛋白的表达和激活，并保护MAC-T细胞免受应激诱导的细胞死亡。最后，Ephrin A1通过下调炎性细胞因子减轻脂多糖诱导的细胞死亡。总之，本研究结果表明，Eph A-Ephrin A1系统是奶牛乳腺上皮细胞增殖和维持的一个积极因素；该信号系统有助于正常乳腺的发育、重塑和功能，并可克服奶牛和其他哺乳动物的乳腺炎。
