Nicotinamide adenine dinucleotide phosphate-dependent cytosolic T(3) binding protein as a regulator for T(3)-mediated transactivation.
Nicotinamide adenine dinucleotide phosphate (NADPH)- dependent cytosolic T(3) binding protein (CTBP) plays a role in the regulation of nuclear transport of T(3) in vitro. However, it is not known whether CTBP regulates the T(3) action. In this study, we examined the effects of CTBP on cellular translocation of T(3) and on transcriptional activation using established CTBP-expressing CHO or GH3 cells. The expression of CTBP increased cellular and nuclear uptake of T(3) in the CTBP-expressing cells. The efflux rate was decreased by induction of CTBP. Efflux from nuclei also inhibited by induction of CTBP. Expression of CTBP suppressed the T(3)-regulated luciferase activity in GH3 cells. Suppression was observed to be related to the expression level of CTBP. T(3) induction of rat GH mRNA was lower in the cells expressing CTBP than that in CTBP-null cells. These results suggest that CTBP regulates the T(3)-induced gene expression, with which an increase in the nuclear content of the T(3) is associated. Because we observed that a part of CTBP could be transported into nuclei and that acceptor protein for CTBP is present in nuclei as previously reported, interaction of CTBP with certain proteins, including transcription factors or nuclear T(3) receptor, may contribute to the regulation.
Mori
Jun-ichirou
J
Department of Aging Medicine and Geriatrics, Shinshu University School of Medicine, 3-1-1, Asahi, Matsumoto, 390-8621, Japan.
Suzuki
Satoru
S
Kobayashi
Mutsuhiro
M
Inagaki
Takeshi
T
Komatsu
Ai
A
Takeda
Teiji
T
Miyamoto
Takahide
T
Ichikawa
Kazuo
K
Hashizume
Kiyoshi
K
D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism*; D006207:Half-Life; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D013963:Thyroid Hormones; D015533:Transcriptional Activation / Q000502:physiology; D014284:Triiodothyronine / Q000235:genetics / Q000502:physiology*; D000097810:Thyroid Hormone-Binding Proteins
D002352:Carrier Proteins; D008156:Luciferases; D008565:Membrane Proteins; D012313:RNA; D013963:Thyroid Hormones; D014284:Triiodothyronine; D000097810:Thyroid Hormone-Binding Proteins