Endocrine Abstracts

Megalin is a member of the LDL receptor family expressed by several epithelial cells where it mediates endocytosis of ligands. In the thyroid megalin is responsible for transcytosis of hormone-poor thyroglobulin (Tg) molecules. This process favors hormone release by preventing hormone-poor Tg to enter the lysosomal pathway, where hormones are cleaved from hormone-rich Tg molecules. Accordingly, megalin KO mice have a distinct thyroid phenotype with primary hypothyroidism. In r...

RAP (LDL receptor associated protein) is a 44 kDa endoplasmic reticulum (ER) resident molecular chaperone. In the thyroid RAP is required for expression of megalin, an endocytic receptor responsible for transcytosis of thyroglobulin (Tg), but it also binds to Tg itself, suggesting it may affect thyroid function in various manners. Indeed, findings in RAP KO mice indicate that disruption of the RAP gene results in impaired Tg storage into the colloid, suggesting that RAP serves...