title: Biosynthesis of 3-iodothyronamine (T1AM) is dependent on the sodium-iodide symporter and thyroperoxidase but does not involve extrathyroidal metabolism of T4.
abstract: 3-Iodothyronamine (T(1)AM) is an endogenous thyroid hormone derivative with unknown biosynthetic origins. Structural similarities have led to the hypothesis that T(1)AM is an extrathyroidal metabolite of T(4). This study uses an isotope-labeled T(4) [heavy-T(4) (H-T(4))] that can be distinguished from endogenous T(4) by mass spectrometry, which allows metabolites to be identified based on the presence of this unique isotope signature. Endogenous T(1)AM levels depend upon thyroid status and decrease upon induction of hypothyroidism. However, in hypothyroid mice replaced with H-T(4), the isotope-labeled H-T(3) metabolite is detected, but no isotope-labeled T(1)AM is detected. These data suggest that T(1)AM is not an extrathyroidal metabolite of T(4), yet is produced by a process that requires the same biosynthetic factors necessary for T(4) synthesis.
authors.affiliation: Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, 97239, USA.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Hackenmueller
authors.forename: Maja
authors.initials: M
authors.lastname: Marchini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Saba
authors.forename: Riccardo
authors.initials: R
authors.lastname: Zucchi
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Scanlan
mesh_terms: D000818:Animals; D007037:Hypothyroidism / Q000378:metabolism; D007453:Iodide Peroxidase / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D027981:Symporters / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*; D013970:Thyronines / Q000096:biosynthesis*; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000378:metabolism; D000099209:Sodium-Iodide Symporters
chemical_list: D007453:Iodide Peroxidase; D027981:Symporters; D013970:Thyronines; D013974:Thyroxine; D014284:Triiodothyronine; D000099209:Sodium-Iodide Symporters; C487948:3-iodothyronamine