MODULATION OF PROLIFERATIVE ACTIVITY AND AMINO-ACID-TRANSPORT IN CHICK-EMBRYO HEPATOCYTES BY EGF AND RETINOIC ACID

In this work, the proliferative activity of chick embryo hepatocytes a nd its regulation by factors affecting cell growth, such as epidermal growth factor (EGF) and retinoic acid, were studied, The transport of nutritional molecules, like amino acids, was also investigated; in par ticular, the uptake mediated by the Na+-dependent system A, known to b e under hormonal and growth factor control. Moreover, some steps in th e transduction pathway of mitogenic signal were analyzed, both for EGF and retinoic acid treatment. Results obtained suggest that chick embr yo hepatocytes growth in an exclusive serum dependent way shows an ear ly sensibility to EGF stimulation as regards to the proliferative acti vity and amino acid transport, responds to retinoic acid treatment and lack of contact inhibition. Moreover, as far as the signal transducti on is concerned, at early stages, they do not seem co be able to utili ze the same signal molecules as observed in adult life.