EN
Autophagy is a process responsible for the degradation and recycling of cytoplasmic content by lysosomes. It is thought to facilitate cell survival during periods of nutrient starvation, but it can also be involved in other physiological processes including regulation of protein homeostasis, degrading intracellular bacteria, tumor suppression and regulation of programmed cell death. Our group was the first to report autophagy in bovine mammary epithelial cells, both in vitro, on BME-UV1 mammary epithelial cell line, and in vivo. The highest intensity of autophagy in bovine mammary glands is noted during dry periods, when the gland undergoes intensive involution and the deprivation of bioactive compounds (hormones, growth factors, cytokines) and nutrients occur. Our studies on the regulation of autophagy show that the conditions observed during bovine mammary gland involution, such as: 1) decrease in the release of lactogenic hormones and growth factors (prolactin, GH and IGF-I); 2) increase of apoptogenic factors (i.e. TGF-β₁) and their receptors, 3) increased synthesis of sex steroids (17-β estradiol, progesterone); and 4) the enhanced competition of intensively developing fetus and mother organism for nutritional and bioactive compounds, may create a state of temporary malnutrition of mammary epithelial cells that forces the cells to the induction of autophagy as a mechanism stabilizing intracellular supplies of energy and aminoacids, especially during the enhanced activity of apoptogenic factors.