Obese individuals have an increased risk of developing a variety of diseases, including type-2 diabetes, cardiovascular disease and hypertension. As the incidence of obesity continues to increase in developed countries, a better understanding of adipose tissue homeostasis becomes critical. Our laboratory has found that human adipose tissue, preadipocytes and mature adipocytes produce prolactin (PRL), a 23-kDa protein. We also found that PRL is capable of increasing glucose uptake in 3T3-L1 murine adipocytes. Recently, we generated a novel human adipocytes cell line, named LS14, which expresses and releases PRL. LS14 cells express many adipocyte-specific genes and undergo full differentiation upon exposure to adipogenic medium. This cell line provides us with a unique opportunity to examine both the regulation and functions of PRL in human adipocytes. Our first objective is to determine the control of PRL gene expression in LS14 cells by identifying PRL promoter elements and then examine the effects of putative PRL releasing and inhibitory factors on PRL gene expression and release. Our second objective is to examine the role of PRL in glucose transport in LS14 cells. We will determine the effect of PRL on glucose uptake in LS14 cells and whether this occurs by increasing translocation and/or expression of Glut4, the insulin-dependent glucose transporter which mediates glucose uptake by adipocytes.
