Related Experiment Videos
Nongenomic actions of thyroid hormone
Thyroid : Official Journal of the American Thyroid Association
|October 1, 1996
Summary
Thyroid hormone exerts rapid, nongenomic effects outside the cell nucleus, influencing ion transport, kinase activity, and cell structure. These extranuclear actions, distinct from nuclear receptor pathways, impact cellular functions and potentially organ-level physiology.
Area of Science:
- Endocrinology
- Cell Biology
- Molecular Biology
Background:
- Thyroid hormone traditionally acts via nuclear receptors, regulating gene expression.
- Nongenomic actions of thyroid hormone occur independently of nuclear receptors.
- These extranuclear actions are observed at the plasma membrane, organelles, cytoskeleton, and cytoplasm.
Purpose of the Study:
- To review the diverse nongenomic actions of thyroid hormone.
- To discuss the demonstrated physiological significance of these actions at the cellular and organ levels.
- To explore the incompletely understood molecular mechanisms underlying these effects.
Main Methods:
- Literature review and synthesis of existing research on thyroid hormone's nongenomic effects.
- Analysis of studies demonstrating cellular and physiological impacts.
- Examination of proposed molecular pathways and binding sites.
Main Results:
- Nongenomic actions include altered solute transport (Ca2+, Na+, glucose), kinase activity modulation (PKC, PKA, PKM2), and effects on mRNA translation and mitochondrial respiration.
- Regulation of actin polymerization and vascular smooth muscle cell contractility are key extranuclear effects.
- Evidence suggests physiological relevance in myocardiocyte ion currents, red blood cell calcium levels, and potentially acute cardiovascular effects.
Conclusions:
- Nongenomic thyroid hormone actions represent a significant, parallel signaling system to genomic effects.
- While cellular significance is established, organ-level impact requires further elucidation.
- Understanding these pathways is crucial for a comprehensive view of thyroid hormone's physiological roles.