Thyrotropin modifies the synthesis of actin and other proteins during thyroid cell culture

Abstract

Primary cultures of dog thyroid cells have been used to study the effects of thyrotropin on the synthesis of proteins. The cells were cultured for 4 days in serum‐free and thyrotropin‐free conditions. Thyrotropin was then added for varying periods of time (6–96h). In the absence of thyrotropin, the cells have an elongated flattened aspect. Exposure to thyrotropin for 6–24 h produces retraction and rounding up of cells whereas cells incubated with thyrotropin for longer periods of time have an epithelial cuboidal shape. After varying periods of culture the cells were labelled with [³⁵S]methionine for 6 h and then analyzed by one‐and two‐dimensional gel electrophoresis, followed by autoradiography. The results were as follows. In conclusion, the data obtained in this work might help to explain the molecular mechanisms by which thyrotropin (and cAMP) triggers the changes in cell shape which occur during thyroid cell culture. They also indicate that one of the main effects of thyrotropin takes place at the level of several proteins which belong to the cytoskeleton and which are involved in the definition of the cytostructure of the thyroid cells.