Effect of active vitamin D3 on the levels of NADPH-dependent cytosolic 3,5,3'-triiodo-L-thyronine-binding protein.
Effect of 1 alpha-OH-vitamin D3 (1 alpha-OH-D3) and 1,25-(OH)2-vitamin D3 (1,25-(OH)2-dihydroxycholecalciferol)(1,25-(OH)2-D3) on the levels of NADPH-dependent cytosolic 3,5,3'-triiodo-L-thyronine (T3)-binding protein (CTBP) was studied in rats and cultured dRLh cells. Deprivation of rats from vitamin D decreased the activity of cytosolic NADPH-dependent T3 binding in rat kidney and liver. The decrease was restored by administration of 1 alpha-OH-D3(0.2 micrograms/kg). The activity of cytosolic NADPH-dependent T3 binding was increased in the dRLh cells by addition of 1,25-(OH)2-D3 to the culture medium. The maximal binding capacity (MBC) was increased by 1,25-(OH)2-D3 without changes in the affinity constant. These results suggested that active vitamin D3 plays an important role in the regulation of cellular T3 translocation through increasing the binding capacity of NADPH-dependent cytosolic T3-binding protein.
Hashizume
K
K
Department of Geriatrics, Endocrinology and Metabolism, Shinshu University School of Medicine, Matsumoto, Japan.
Suzuki
S
S
Ichikawa
K
K
Takeda
T
T
Kobayashi
M
M
D000818:Animals; D002112:Calcifediol / Q000494:pharmacology*; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000097:blood; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013963:Thyroid Hormones; D014284:Triiodothyronine / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood / Q000378:metabolism; D000097810:Thyroid Hormone-Binding Proteins
D002112:Calcifediol; D002117:Calcitriol; D002118:Calcium; D002352:Carrier Proteins; D008565:Membrane Proteins; D009249:NADP; D013963:Thyroid Hormones; D014284:Triiodothyronine; D000097810:Thyroid Hormone-Binding Proteins