Thyroid hormone regulates the extracellular organization of laminin on astrocytes
UMass Chan Affiliations
Molecular Endocrinology LaboratoryDocument Type
Journal ArticlePublication Date
1999-10-28Keywords
AnimalsAnimals, Newborn
Astrocytes
Cells, Cultured
Electrophoresis, Polyacrylamide Gel
Extracellular Matrix
Immunohistochemistry
Immunosorbent Techniques
Laminin
Mice
Microscopy, Fluorescence
Rats
Sarcoma, Experimental
Thyroid Hormones
Thyroxine
Triiodothyronine
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Astrocytes produce laminin, a key extracellular matrix guidance molecule in the developing brain. Laminin is bound to transmembrane receptors on the surface of astrocytes known as integrins, which are, in turn, bound to the microfilament meshwork inside the astrocyte. Previous studies have shown that T4 regulates the pattern of integrin distribution in astrocytes by modulating the organization of the microfilaments. In this study, the effect of thyroid hormone on the secretion and topology of laminin in astrocytes was examined. Linear arrays of secreted laminin were observed on the surface of the T4-treated astrocytes within 10 h after seeding the cells onto poly-D-lysine-coated coverslips and became an organized meshwork by 24 h. In contrast, little if any laminin was identified on the surface of either hormone-deficient or T3-treated cells until 36 h after seeding and then was restricted to punctate deposits. Secretion of laminin into the medium by hormone-deficient and T3-treated cells was significantly greater than that by T4-treated cells. Conversely, deposition of laminin into the extracellular matrix was significantly greater in T4-treated cells than in hormone-deficient and T3-treated cells. Thyroid hormone had no effect on the production of laminin by astrocytes. These data show that T4 regulates the extracellular deposition and organization of laminin on the surface of astrocytes and provide a mechanism by which this morphogenic hormone can influence neuronal migration and axonal projection in the developing brain.Source
Endocrinology. 1999 Nov;140(11):5014-21.