THE REGULATORY ROLE OF TRIIODOTHYRONINE ON THE PRODUCTION OF ALPHA-FETOPROTEIN AND ALBUMIN BY MOUSE FETAL LIVER-CELLS

The purpose of this study was to assess possible effects of triiodothy ronine (T3) on the production of alpha fetoprotein (AFP) and albumin b y mouse fetal liver cells. AFP from serum-free conditioned media of TI B73 mouse fetal liver cells was measured by immunoradiometric assay an d albumin was measured by chromogenic assay. The expression of mRNAs w as quantified by Northern blotting analysis. A marked inhibition of AF P secretion was found as well as an increase in albumin produced by T3 in a dose-dependent manner. The effects of T3 AFP and albumin secreti on paralleled the effects of T3 on the steady-state expression of mRNA s encoding albumin and AFP. These data may point to a possible role of T3 in the transcriptional switch from AFP to albumin during fetal dev elopment and may explain the observation of high levels of AFP in case s of congenital hypothyroidism.