Researchers from the Katholieke Universiteit Leuven have found a thyroid hormone transporter that is required for early stages of brain development. The work was published recently in The Journal of Neuroscience.
When humans are deficient of monocarboxylate transporter 8 (MCT8), they end up developing Allan-Herndon-Dudley Syndrome. Without this transporter, thyroid hormones are unable to help with the proper development of the cortex. Although a role for MTC8 has been demonstrated at the blood-brain barrier and in the formation of neural circuits, according to researchers it has not been established at the role of progenitor cells before they differentiate into neuronal and glial cells.
Veerle Darras, the Katholieke Universiteit Leuven, and colleagues studied the development of the optic tectum, a layered region that shares features with the mammalian cerebral cortex, in chick embryos. They modified MCT8 expression and found that MCT8-deficient cells were not able to migrate to the outer layers of the optic tectum. The MCT8 deficiency also disrupted the cell cycle and reduced the generation of new cells.
From this study, the authors suggest that in order to tackle Allan-Herndon-Dudley Syndrome, treatments may need to be started before birth.
Image: Section through the optic tectum of a chicken embryo, showing that MCT8-deficient cells (right panel) fail to migrate to their normal position. Image courtesy of Pieter Vancamp.