End-organ effects of thyroid hormones: subcellular interactions in cultured cells.

Both actinomycin D and puromycin suppress the formation of colonies by cultured human kidney epithelial cells (T-l), but inactivation by puromycin is partially reversed with thyroid hormones. Uptake by the cells of L-thyroxine labeled with iodine-125, 60 to 80 percent of which is nuclear, is depressed by actinomycin and enhanced by puromycin. Genome and possibly nuclear membrane are implicated as initiating loci.