Figure 1.

Ability of exogenous follicular TG to modulate TG, TPO, TSHR, NIS, GAPDH, or MHC class I mRNA levels when added to the medium of rat FRTL-5 thyroid cells. FRTL-5 cells in 6H medium were washed with serum-free medium and the incubation continued in serum-free medium containing TG, crystalline BSA, or mannitol. After 48 hr, Northern analyses were performed by using 20 μg total RNA. Blots were sequentially hybridized with probes for TG, TSHR, TPO, NIS, MHC class I, and GAPDH. The ratio of the binding of each probe to GAPDH was calculated, because GAPDH was not changed by TG. Cells exposed to neither BSA, mannitol, or TG were the control; the ratio of binding in these cells was set at 1 for each probe. Experimental values were compared with their corresponding controls; data are the mean ± SD of three different experiments, each performed in duplicate. One, two, or three stars represent a significant TG-induced decrease or increase at P < 0.05, <0.01, or <0.001, respectively. Representative blots are from one experiment.