Thyroid hormone transporters in the brain.

Area of Science:

• Neuroscience
• Endocrinology
• Molecular Biology

Background:

• Thyroid hormones (THs) are vital for nervous system development and function.
• The active form, triiodothyronine (T3), regulates gene expression via nuclear receptors.
• Mutations in the monocarboxylate transporter 8 (MCT8) cause Allan-Herndon-Dudley syndrome, highlighting TH transport importance.

Purpose of the Study:

• To review the current understanding of thyroid hormone transmembrane transport proteins in the brain.
• To emphasize the growing number of candidate transporters involved in TH neurobiology.
• To underscore the complex pathways THs navigate to reach neuronal targets.

Main Methods:

• Literature review of studies on thyroid hormone transport.
• Analysis of the roles of various transporter families (MCTs, AATs, OATPs).
• Discussion of the cellular and subcellular barriers THs must cross in the brain.

Main Results:

• Several major facilitator superfamily members act as TH transporters.
• Multiple cell types in the brain (neurons, astrocytes, microglia, oligodendrocytes) express TH transporters.
• TH transport across the blood-brain barrier and into neurons involves multiple steps and transporters.

Conclusions:

• Thyroid hormone transport is a complex, multi-step process essential for brain development and function.
• Spatiotemporal expression of various transmembrane transport proteins is critical for THs' roles in the nervous system.
• Further research into TH transporters is warranted due to their significance in neurological health and disease.