Expression of rat liver cell membrane transporters for thyroid hormone in Xenopus laevis oocytes.

The present study was conducted to explore the possible use of Xenopus laevis oocytes for the expression cloning of cell membrane transporters for iodothyronines. Injection of stage V-VI X. laevis oocytes with 23 ng Wistar rat liver polyadenylated RNA (mRNA) resulted after 3-4 days in a highly significant increase in [125I]T3 (5 nM) uptake from 6.

Uptake and metabolism of 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine by human liver-derived cells: HepG2 cells as a model for thyroid hormone handling by human liver.

The uptake and metabolism of T3 and rT3 was studied in human liver-derived HepG2 cells. The results showed a saturable, time-dependent, and ouabain-sensitive increase in nuclear bound T3. The effects of ouabain (0.

Reduced T3 deiodination by the human hepatoblastoma cell line HepG2 caused by deficient T3 sulfation.

Type I deiodination of T3 sulfate occurs at a Vmax that is 30-fold higher as compared to T3, both in rat and in human liver homogenates. We now present data showing lack of T3 deiodination by a human liver derived hepatoblastoma cell line, HepG2, caused by deficient T3 sulfation. Cellular entry of T3 was assessed by its nuclear binding after whole cell incubation.