title: The actin cytoskeleton mediates the hormonally regulated translocation of type II iodothyronine 5'-deiodinase in astrocytes.
abstract: Thyroid hormone, specifically thyroxine, alters cytoskeletal organization in astrocytes by modulating actin polymerization and, in turn, regulates the turnover of the short-lived membrane protein, type II iodothyronine 5'-deiodinase. In the absence of thyroxine, approximately 35% of the total cellular actin is depolymerized, and greater than 90% of the deiodinase is found in the plasma membrane and not associated with the cytoskeleton. Addition of thyroxine promotes actin polymerization and decreases the depolymerized actin to approximately 10% of the total actin pool, induces binding of the deiodinase to F-actin, and promotes rapid internalization of the enzyme. These data provide direct evidence that the actin cytoskeleton participates in the inactivation pathway of the deiodinase by translocating this short-lived plasma membrane protein to an internal membrane pool.
authors.affiliation: Department of Nuclear Medicine, University of Massachusetts Medical School, Worcester 01655.
authors.forename: A P
authors.initials: AP
authors.lastname: Farwell
authors.forename: R M
authors.initials: RM
authors.lastname: Lynch
authors.forename: W C
authors.initials: WC
authors.lastname: Okulicz
authors.forename: A M
authors.initials: AM
authors.lastname: Comi
authors.forename: J L
authors.initials: JL
authors.lastname: Leonard
mesh_terms: D000199:Actins / Q000378:metabolism*; D000345:Affinity Labels; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001692:Biological Transport; D003994:Bucladesine / Q000494:pharmacology; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007425:Intracellular Membranes / Q000378:metabolism; D007453:Iodide Peroxidase / Q000145:classification / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000737:chemistry; D013974:Thyroxine / Q000494:pharmacology
chemical_list: D000199:Actins; D000345:Affinity Labels; D008565:Membrane Proteins; D003994:Bucladesine; D007453:Iodide Peroxidase; D013974:Thyroxine