TSHR: Receptor for thyrothropin. Plays a central role in controlling thyroid cell metabolism. The activity of this receptor is mediated by G proteins which activate adenylate cyclase. Also acts as a receptor for thyrostimulin (GPA2+GPB5). Defects in TSHR are found in patients affected by hyperthyroidism with different etiologies. Somatic, constitutively activating TSHR mutations and/or constitutively activating G(s)alpha mutations have been identified in toxic thyroid nodules (TTNs) that are the predominant cause of hyperthyroidism in iodine deficient areas. These mutations lead to TSH independent activation of the cAMP cascade resulting in thyroid growth and hormone production. TSHR mutations are found in autonomously functioning thyroid nodules (AFTN), toxic multinodular goiter (TMNG) and hyperfunctioning thyroid adenomas (HTA). TMNG encompasses a spectrum of different clinical entities, ranging from a single hyperfunctioning nodule within an enlarged thyroid, to multiple hyperfunctioning areas scattered throughout the gland. HTA are discrete encapsulated neoplasms characterized by TSH- independent autonomous growth, hypersecretion of thyroid hormones, and TSH suppression. Defects in TSHR are also a cause of thyroid neoplasms (papillary and follicular cancers). Autoantibodies against TSHR are directly responsible for the pathogenesis and hyperthyroidism of Graves disease.
Antibody interaction with TSHR results in an uncontrolled receptor stimulation. Defects in TSHR are the cause of congenital hypothyroidism non-goitrous type 1 (CHNG1); also known as congenital hypothyroidism due to TSH resistance. CHNG1 is a non-autoimmune condition characterized by resistance to thyroid- stimulating hormone (TSH) leading to increased levels of plasma TSH and low levels of thyroid hormone. CHNG1 presents variable severity depending on the completeness of the defect. Most patients are euthyroid and asymptomatic, with a normal sized thyroid gland. Only a subset of patients develop hypothyroidism and present a hypoplastic thyroid gland. Defects in TSHR are the cause of familial gestational hyperthyroidism (HTFG). HTFG is a condition characterized by abnormally high levels of serum thyroid hormones occurring during early pregnancy. Defects in TSHR are the cause of hyperthyroidism non- autoimmune (HTNA). It is a condition characterized by abnormally high levels of serum thyroid hormones, thyroid hyperplasia, goiter and lack of anti-thyroid antibodies. Typical features of Graves disease such as exophthalmia, myxedema, antibodies anti-TSH receptor and lymphocytic infiltration of the thyroid gland are absent. Belongs to the G-protein coupled receptor 1 family. FSH/LSH/TSH subfamily. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Membrane protein, multi-pass; Membrane protein, integral; Receptor, GPCR; GPCR, family 1
Chromosomal Location of Human Ortholog: 14q31
Cellular Component: cell surface; integral to plasma membrane; plasma membrane; receptor complex
Molecular Function: peptide receptor activity, G-protein coupled; protein binding
Biological Process: adenylate cyclase activation; cell-cell signaling; G-protein coupled receptor protein signaling pathway; G-protein signaling, adenylate cyclase activating pathway; G-protein signaling, coupled to cyclic nucleotide second messenger; hormone-mediated signaling; nervous system development; positive regulation of cell proliferation
Disease: Hyperthyroidism, Familial Gestational; Hyperthyroidism, Nonautoimmune; Hypothyroidism, Congenital, Nongoitrous, 1
