Thyroid oxidase (THOX2) gene expression in the rat thyroid cell line FRTL-5

A cDNA encoding an NADPH oxidase flavoprotein was isolated from the rat thy roid gland. The predicted 1517-residue polypeptide was 82.5% identical to t he human THOX2/DUOX2 and 74% similar to THOX1/DUOX1, Rat THOX2 lacks a stre tch of 30 residues, corresponding to one exon in the human gene sequence. T HOX2 mRNA was found to be expressed in cultured FRTL-5 cells. The level of THOX2 mRNA was increased by cAMP in these cells and it was decreased in the thyroids of rats treated with the antithyroid drug methimazole, unlike the TPO and NIS mRNAs. Since it was found in the intestine, duodenum, and colo n, in addition to thyroid, we suggest that it be called LNOX, the new famil y of lo ng homologs of NOX flavoproteins rather than THOX and/or DUOX (C) 2 000 Academic Press.