Type 3 Deiodinase Enzyme Keeps Thyroid Hormones In Check

Main Category: Endocrinology
Article Date: 14 Jan 2006 - 0:00 PDT

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Thyroid hormones (THs) are secreted by the thyroid gland and play a critical role in growth and development, so much so that reduced or excessive levels of THs during fetal and neonatal development can cause severe abnormalities.

Type 3 deiodinase (D3) is involved in the degradation of thyroid hormones T3 and T4 to biologically inactive forms and as such serves as a modulator of intracellular TH levels and action.

In order to learn more about the actions of D3, Arturo Hernandez and colleagues from Dartmouth Medical School examined mice deficient in the gene encoding D3 and observed marked abnormalities including early mortality, growth retardation, and impaired fertility.

They found that in early life these mice had elevated T3 levels. Later, and into adulthood, the animals has low T3 and T4 levels characteristic of hypothyroidism (deficient thyroid activity). The study, which appears online on January 12 in advance of print publication in the February 2006 issue of the Journal of Clinical Investigation, points to the importance of D3 in physiological processes such as growth, early development, and reproduction.

TITLE: Type 3 deiodinase is critical for the maturation and function of the thyroid axis

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Brooke Grindlinger
press_releases@the-jci.org
Journal of Clinical Investigation
http://www.jci.org

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