Revisiting available knowledge on teleostean thyroid hormone receptors

Area of Science:

• Comparative endocrinology
• Molecular biology
• Fish biology

Background:

• Teleosts, the most diverse vertebrate class, share conserved molecular and endocrine systems.
• Thyroid hormones regulate key physiological processes in fish, similar to other vertebrates.
• Thyroid hormone receptors (TRs) mediate these effects by regulating gene expression.

Purpose of the Study:

• To propose a systematic nomenclature for teleost thyroid hormone receptor (THR) isoforms.
• To summarize the unique structural and functional characteristics of teleost THR isoforms.
• To provide insights into teleost thyroid signaling from a comparative perspective.

Main Methods:

• Literature review and comparative analysis of existing data on teleost THR isoforms.
• Systematic proposal of nomenclature for identified THR isoforms.
• Summarization of functional data available for these isoforms.

Main Results:

• Teleosts exhibit diverse THR isoforms, including multiple copies of thra and sometimes thrb genes.
• Some teleost THR isoforms possess unique structural features like deletions or insertions.
• Certain isoforms display altered ligand-binding properties and distinct functional roles.
• Regulation of some isoforms is linked to metamorphic climax and developmental transitions.

Conclusions:

• Teleost THR diversity contributes to their varied adaptations and developmental strategies.
• A standardized nomenclature is crucial for understanding and comparing teleost THR functions.
• Further research is needed to functionally characterize novel teleost THR isoforms.