The actin cytoskeleton mediates the hormonally regulated translocation of type II iodothyronine 5'-deiodinase in astrocytes.
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.
Farwell
A P
AP
Department of Nuclear Medicine, University of Massachusetts Medical School, Worcester 01655.
Lynch
R M
RM
Okulicz
W C
WC
Comi
A M
AM
Leonard
J L
JL
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
D000199:Actins; D000345:Affinity Labels; D008565:Membrane Proteins; D003994:Bucladesine; D007453:Iodide Peroxidase; D013974:Thyroxine