Related Experiment Videos
[The basis for the variable effects of thyroid hormones]
1Ustav experimentálnej endokrinológie SAV, Bratislava.
Abstract:
Among physiological reactions of the organism, the multiplicity of action of thyroid hormones is a well known phenomenon. Thyroid hormones (TH) regulate activity of other hormones, receptors for bioactive signals, enzymes, and the function of ion channels. Until triiodothyronine has been identified as a ligand for oncoprotein c-erbA, this broad potency of actions has been mysterious. C-erbA has been recognized to be a transcription factor and an authentic thyroid hormone receptor. Important evidence comes from molecular studies, which have described isoforms of c-erbA and other members of intranuclear receptor family, their heterodimerization, thyroid hormone responsive elements in the target genes, and the existence of the cross-talk mechanism. Till present, much has been learned about TH transcription regulations in vitro. An open question remains whether this regulations are operative also in the intact organism.
Insights
Thyroid hormones (TH) influence numerous physiological processes by regulating other hormones and cellular functions. Their broad actions are explained by their role as ligands for the c-erbA oncoprotein, a thyroid hormone receptor.
Area of Science:
- Endocrinology
- Molecular Biology
- Cellular Physiology
Context:
- Thyroid hormones (TH) exhibit diverse physiological effects, impacting multiple cellular pathways.
- The precise molecular mechanisms underlying TH's broad actions remained elusive until the identification of triiodothyronine as a ligand for the c-erbA oncoprotein.
- C-erbA was subsequently recognized as a transcription factor and a functional thyroid hormone receptor.
Purpose:
- To elucidate the molecular basis of thyroid hormone's widespread physiological influence.
- To connect the known broad potency of thyroid hormones to their interaction with the c-erbA oncoprotein.
- To explore the role of c-erbA as a transcription factor and thyroid hormone receptor.
Summary:
- Molecular studies have detailed c-erbA isoforms and related intranuclear receptors, their heterodimerization, and thyroid hormone-responsive elements in target genes.
- Mechanisms such as cross-talk between signaling pathways have been described.
- While in vitro studies have significantly advanced understanding of TH transcriptional regulation, their in vivo relevance remains an open question.
Impact:
- Provides a molecular framework for understanding the pleiotropic effects of thyroid hormones.
- Highlights the critical role of the c-erbA receptor in mediating thyroid hormone action.
- Establishes a foundation for further research into in vivo thyroid hormone transcriptional regulation.