Sodium Iodide Symporter (NIS) of the Thyroid Follicular Cell

Rodrigo Arrangoiz MS, MD, FACS, FSSO
  • The sodium iodide symporter (NIS) gene:
    • Also known as SLC5A5:
      • Encodes a protein that transports iodide into thyroid follicular cells:
        • This process is crucial for thyroid hormone synthesis
  • NIS is a plasma membrane glycoprotein:
    • Located on the basolateral membrane of the thyroid follicular cells
  • Mutations in the SLC5A5 gene:
    • Can cause congenital iodide transport defects:
      • Leading to hypothyroidism
Thyroid Hormone Synthesis in the Thyroid Follicular Cell.
Thyroid hormone synthesis and secretion are activated when Thyroid stimulating hormone (TSH) binds to the TSH receptor on the basolateral membrane. Iodide is transported into the cell via the Na+/I− (NIS) symporter and flows down an electrical gradient, maintained by the sodium-potassium ATPase. Iodide becomes covalently attached to the tyrosyl residues of the precursor thyroid hormone glycoprotein, thyroglobulin, by thyroperoxidase (TPO) to form monoiodotyrosine (MIT) and diiodotyrosine (DIT). These are subsequently coupled by the action of TPO to form the iodothyronine hormones, tetraiodothyronine (T4) and triiodothyronine (T3). In the process of thyroid hormone secretion, Tg enters the cell by pinocytosis, forming colloid droplets. These fuse with lysosomes, forming phagolysosomes in which Tg is broken down by proteolysis, and then T4 and T3 are released and diffuse into circulation. MIT and DIT are formed by the iodination of tyrosyl amino acids on the thyroglobulin molecule. In a subsequent step, two DITs are coupled to form T4, or one DIT and one MIT are coupled to form T3. (From Brent GA, Koenig RJ. Thyroid and antithyroid drugs. In: Brunton L [ed]. Goodman and Gilman’s The Pharmacological Basis of Therapeutics. 13th ed. New York: McGraw-Hill; 2017.)
Rodrigo Arrangoiz, MD (Oncology Surgeon)
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Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO

My name is Rodrigo Arrangoiz I am a breast surgeon/ thyroid surgeon / parathyroid surgeon / head and neck surgeon / surgical oncologist that works at Center for Advanced Surgical Oncology in Miami, Florida. I was trained as a surgeon at Michigan State University from (2005 to 2010) where I was a chief resident in 2010. My surgical oncology and head and neck training was performed at the Fox Chase Cancer Center in Philadelphia from 2010 to 2012. At the same time I underwent a masters in science (Clinical research for health professionals) at the University of Drexel. Through the International Federation of Head and Neck Societies / Memorial Sloan Kettering Cancer Center I performed a two year head and neck surgery and oncology / endocrine fellowship that ended in 2016. Mi nombre es Rodrigo Arrangoiz, soy cirujano oncólogo / cirujano de tumores de cabeza y cuello / cirujano endocrino que trabaja Center for Advanced Surgical Oncology en Miami, Florida. Fui entrenado como cirujano en Michigan State University (2005 a 2010 ) donde fui jefe de residentes en 2010. Mi formación en oncología quirúrgica y e n tumores de cabeza y cuello se realizó en el Fox Chase Cancer Center en Filadelfia de 2010 a 2012. Al mismo tiempo, me sometí a una maestría en ciencias (investigación clínica para profesionales de la salud) en la Universidad de Drexel. A través de la Federación Internacional de Sociedades de Cabeza y Cuello / Memorial Sloan Kettering Cancer Center realicé una sub especialidad en cirugía de cabeza y cuello / cirugia endocrina de dos años que terminó en 2016.

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