Augmentation of thyroid hormone receptor-mediated transcription by Ca2+/calmodulin-dependent protein kinase type IV.
Thyroid hormone receptor (TR), a ligand-mediated transcription factor, binds to a DNA sequence known as a thyroid-hormone response element (TRE) to activate or repress transcription of target genes. Recently, studies have shown that Ca2+/calmodulin-dependent protein kinases (CaMKs) may be involved in regulating gene transcription via phosphorylation of specific transcription factors, including RORalpha, a retinoic acid-related orphan nuclear hormone receptor. In this light, we examined the effect of CaMK type IV (CaMKIV) and RORalpha, which also shown to influence thyroid hormone action, on TR-mediated transcription using a transient transfection assay. Expression vectors containing TR, vitamin D receptor (VDR), and estrogen receptor (ER) were cotransfected in CV-1 cells with RORalpha and/or constitutively active CaMKIV and thymidine kinase promotor-luciferase reporter vector containing their cognate response elements. When CaMKIV or RORalpha was co-transfected with TR, the T3-induced transcription was significantly augmented compared to that induced by TR alone. When both were co-transfected with TR, T3-induced transcription was augmented additively. In contrast, the augmentation by CaMKIV or ROR on ligand-induced transcription was not detected with VDR and ER. Hence, these results indicate that the augmentation mediated by CaMKIV and RORalpha is specific for TR-mediated transcription on TRE. Our results suggest that CaMKIV, as well as RORalpha, play important roles in TR-mediated transcription on TREs.
Kuno-Murata
M
M
Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Koibuchi
N
N
Fukuda
H
H
Murata
M
M
Chin
W W
WW
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D011401:Promoter Regions, Genetic; D051381:Rats; D018167:Receptors, Calcitriol / Q000235:genetics / Q000502:physiology; D011960:Receptors, Estrogen / Q000235:genetics / Q000502:physiology; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000502:physiology; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins; D013937:Thymidine Kinase / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014284:Triiodothyronine / Q000494:pharmacology
D007527:Isoenzymes; D018167:Receptors, Calcitriol; D011960:Receptors, Estrogen; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D011993:Recombinant Fusion Proteins; D014284:Triiodothyronine; D008156:Luciferases; D013937:Thymidine Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases