title: Phosphorylation of heat shock protein-90 by TSH in FRTL-5 thyroid cells.
abstract: BACKGROUND
  Although it is well established that thyrotropin (TSH) initiates signal transduction systems resulting in protein kinase(s) activation, the phosphorylated targets have not been fully characterized.
  
  
  OBJECTIVE
  In FRTL-5 thyroid cells, we used two-dimensional (2D) gel images of silver-stained proteins isolated from FRTL- 5 thyroid cells following TSH stimulation to identify potential phosphorylation targets.
  
  
  RESULTS
  We characterized a 90 kDa protein that had undergone a pH shift and subsequently identified it as heat shock protein-90 (hsp-90) following in-gel trypsin digestion and mass spectroscopy. This was confirmed by Western blot using a monoclonal antibody against hsp-90. Western blot analysis of the 2D gel images using a polyclonal antibody directed at phosphoserine/threonine sites showed that TSH induced the phosphorylation of hsp-90. Western blotting of hsp-90 following stimulators of the signal transduction systems mediated by TSH indicated that TSH-mediated hsp-90 phosphorylation occurs through protein kinases A and C.
  
  
  CONCLUSIONS
  In summary, we have demonstrated that TSH action stimulates the phosphorylation of hsp-90 in FRTL-5 thyroid cells. Abnormalities of hsp-90 phosphorylation may be a mediator in the development of thyroid disease.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Jody
authors.initials: J
authors.lastname: Ginsberg
authors.forename: Teresa
authors.initials: T
authors.lastname: Labedz
authors.forename: David N
authors.initials: DN
authors.lastname: Brindley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D015180:Electrophoresis, Gel, Two-Dimensional; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010766:Phosphorylation; D051381:Rats; D011916:Rats, Inbred F344; D015398:Signal Transduction; D016622:Silver Staining; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism*
chemical_list: D018841:HSP90 Heat-Shock Proteins; D013972:Thyrotropin