Target intelligence / Profile preview

Iodothyronine deiodinase (main forms: type 1, type 2, and type 3 deiodinase) (DIO1, DIO2, DIO3)

Target: DIO1, DIO2, DIO3
Molecular classification: Enzyme, Selenoprotein

Overview

Peripheral conversion of thyroxine to triiodothyronine describes the enzymatic reactions—mediated by the family of iodothyronine deiodinases—that transform T4 (a prohormone released by the thyroid gland) into T3 (the active hormone) in peripheral tissues. The three deiodinases (type 1, 2, and 3) act with tissue-specific distribution: DIO1 dominates in liver/kidneys/thyroid, DIO2 in CNS/brown fat/skeletal muscle, and DIO3 deactivates T4 and T3. This process is critical for maintaining thyroid hormone action at the cellular level and is subject to modulation by physiological stress, illness, drugs, and developmental programming.

Other names: Deiodinase activityPeripheral deiodinaseThyroid hormone activating enzymeOuter ring deiodination enzymeDIO1DIO2DIO3

Mechanism of action

Inhibition (e.g., propylthiouracil blocks T4 to T3 conversion via DIO1); Supplementation (e.g., levothyroxine and liothyronine bypass natural conversion)

Biological functions

Thyroid hormone activation (T4 to T3 conversion)Thyroid hormone inactivation (T4/T3 degradation to reverse T3 and 3,3'T2)Local control of thyroid hormone signalingMetabolic regulationAdaptation to physiologic conditions (e.g., cold, stress)

Disease associations

HypothyroidismNon-thyroidal illness syndromeMetabolic syndromeObesityChronic fatigue syndromeFibromyalgia

Safety considerations

Difficulty detecting tissue hypothyroidism with standard blood testsRisk of inappropriate thyroid hormone dosing due to altered conversion (can lead to hypo- or hyperthyroid states)Elevated reverse T3 can block T3 activity, causing symptoms not reflected in TSH/thyroid hormone tests

Interacting drugs

Propylthiouracil

2 more in the full profile.

Biomarkers

Serum T3 and reverse T3 concentrationsSerum TSH (indirect, but may be misleading in peripheral conversion disorders)

Beyond the preview

Go deeper on Iodothyronine deiodinase (main forms: type 1, type 2, and type 3 deiodinase) (DIO1, DIO2, DIO3).

Explore the evidence, development activity, and competitive landscape with Gosset’s full data platform.

Drug pipeline

Explore the programs pursuing this target and their development progress.

Drug candidates
Developers
Development stage

Clinical trials

Follow the clinical studies evaluating therapies directed at this target.

Trial design
Status
Readouts

Competitive landscape

Compare approaches across drug candidates, modalities, and indications.

Programs
Modalities
Indications

Literature & evidence

Investigate the research and source evidence behind target biology and development.

Publications
Sources
Analysis

Patents

Explore patent activity around therapies and technologies addressing this target.

Patents
Assignees
Technologies

Research & analysis

Connect target biology, drug development, and emerging evidence in your research.

Biology
Development news
Analysis

Bring the full picture into focus.

See how Gosset can support your research on Iodothyronine deiodinase (main forms: type 1, type 2, and type 3 deiodinase) (DIO1, DIO2, DIO3).

Explore the full profile