Iodothyronine deiodinases are important enzymes for metabolism of thyroid hormones. These enzymes which are expressed in a variety of tissues are able to catalyze removal of iodine from thyroid hormones. Iodothyronine deiodinases I and II (DIO1 and DIO2) remove iodine from T4 to convert it to a more biologically active T3. The relative contribution of different tissue deiodinases to the establishment of a euthyroid state (proper production and concentration of T3) is not known. The objective of this study was to quantitate the amounts of transcription of DIO1 and DIO2 deiodinases in different ovine tissues. Using real-time reverse transcription polymerase chain reaction (RT-qPCR) and a comparative cycle threshold analysis, we found that DIO1 deiodinase is transcribed in skeletal muscle, kidney, and heart, more than thyroid, in diaphragm in quantities very similar to thyroid, and in liver, spleen, lung, and mammary gland lower than thyroid. We also found that the level of DIO2 transcription in all other tissues was lower than that in thyroid. Skeletal muscle, heart, and diaphragm transcribed between 84% to 87%; liver, kidney and lung transcribed between 62% to 72%; and spleen and mammary gland transcribed around 40% of DIO2 amount which is transcribed by thyroid. The biological significance of the relative expression of DIO1 and DIO2 enzymes in different ovine tissues awaits further studies. However in clinical settings, measurement of DIO1 and DIO2 expression in a given tissue may provide important clues on the intensity of selenium deficiency and its effects on the metabolism of thyroid hormones.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details unavailable.
05 - 09 May 2012
European Society of Endocrinology