title: Insulin-like growth factor binding protein-3 interacts with the thyroid hormone receptor α1 and modulates transcription of thyroid hormone responsive gene.
abstract: OBJECTIVE
  To study the interaction between insulin-like growth factor binding protein-3 (IGFBP-3) and thyroid hormone receptor α1 (TRα1) and the modulatory effect of IGFBP-3 on transcription of the thyroid hormone responsive gene.
  
  
  METHODS
  The interaction between IGFBP-3 and TRα1 was detected with glutathione-S-transferase pull-down method, co-immunoprecipitation, fluorescence resonance energy transfer test. The cellular distribution of these two proteins was observed by confocal laser scanning microscopy. The effect of IGFBP-3 on the growth hormone promoter activity stimulated by triiodothyronine (T3) was determined by dual-luciferase reporter assay.
  
  
  RESULTS
  IGFBP-3 interacted with TRα1 both in vivo and in vitro. IGFBP-3 and TRα1 were shown to co-localize in the nucleus of HEK-293 cells. The overexpressed IGFBP-3 inhibited the growth hormone promoter activity stimulated by T3 (P<0.01).
  
  
  CONCLUSIONS
  IGFBP-3 interacts with TRα1 and inhibits T3 responsive gene transcription. This finding further confirms the insulin-like growth factor-independent role of IGFBP-3 in the nucleus.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, CAMS and PUMC, Beijing 100005, China.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Jia
authors.forename: Ma
authors.initials: M
authors.lastname: Xiao-li
authors.forename: Wang
authors.initials: W
authors.lastname: Xin
authors.forename: Chen
authors.initials: C
authors.lastname: Hong
authors.forename: Huang
authors.initials: H
authors.lastname: Bing-ren
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D037021:Thyroid Hormone Receptors alpha / Q000378:metabolism*; D013963:Thyroid Hormones / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D037021:Thyroid Hormone Receptors alpha; D013963:Thyroid Hormones; D014284:Triiodothyronine