Thyroid Hormones

Thyroid hormones (THs) act principally through nuclear TH receptors (TRs), which are members of the nuclear hormone receptor superfamily, accompanied by gene activation or inactivation of target genes. THs exert their genomic actions such as metabolism, thermogenesis, growth, and development within several hours or days. Recently, actions of THs or their derivatives via plasma membrane receptors or in cytoplasm have been identified. Most of these extranuclear actions appear within minutes. The plasma membrane receptor of THs is located on integrin αvβ3, which transfers the hormonal signal to MAPK (ERK1/2), resulting in the stimulation of protein trafficking, angiogenesis, and cell proliferation. Thyronamines, derivatives of THs, are a newly identified class of signaling molecules. A candidate receptor for thyronamines is a member of the trace amine-associated receptors. The physiological effects of thyronamines are opposite to those found in TH treatment.