Triggering by thyrotropin of an increased synthesis of triglycerides in cultured human thyroid cells

Effects of thyrotropin and thyroid stimulating immunoglobulins on gangliosides labelling of human thyroid cultured pathological cells

Gangliosides are known to play an important role in different cell processes. We have investigated the effect of TSH on [14C] glucosamine incorporation into gangliosides of cultured pathological cells isolated from colloid nodular goiter, follicular adenoma, and toxic adenoma. The effect of thyroid stimulating immunoglobulins (TSI) has also been similarly studied on primary cultures from colloid nodular goiter and from porcine thyroid cells. Immunoglobulins were purified from sera of Graves' disease patients. Cells were cultured with or without either stimulator and labelled with [14C] glucosamine during 24 h. Total lipid extracts were fractionated on DEAE Sephadex A 25. Eluted gangliosides were analysed by thin layer chromatography, detected by autoradiography and scraped off for radioactivity measurement. Radioactivity was related to the free cholesterol content. The ganglioside pattern of human thyroid cells in primary cultures is found to vary and to closely reflect the ganglioside pattern of the corresponding gland. No ganglioside pattern could be related to a specific thyroid disorder. When cells are treated with TSH, the amount of [14C] glucosamine incorporated in total gangliosides varies according to diseases. The radioactivity incorporated in gangliosides from colloid nodular goiter cells is not similarly affected by TSH and TSI. In porcine thyroid cells, TSH and TSI have the same effect on glucosamine incorporation into gangliosides. Thus it appears that TSH and TSI may differently affect the gangliosides labelling according to the origin of the thyroid cells.

Chronic regulation by thyrotropin of arachidonic acid incorporation in cholesteryl esters of cultured thyroid cells

During short term incubations, radioactive arachidonic acid and palmitic acid were incorporated in the cholesteryl ester fraction of the lipids of cultured thyroid cells. Three times more arachidonic than palmitic acid was incorporated and the incorporation of both was dependent upon the culture conditions: the presence of 1 mU/ml thyrotropin in the culture medium during four days almost completely inhibited the subsequent incorporation of the two fatty acids in the cholesteryl ester fraction whereas the total cholesterol and cholesteryl ester content of the cells was not affected.