title: Regulation of thymosin beta10 expression by TSH and other mitogenic signals in the thyroid gland and in cultured thyrocytes.
abstract: OBJECTIVE
  To investigate the expression of thymosin beta10 - a small conserved acidic protein involved in the inhibition of actin polymerization - in human and experimental thyroid goiters as well as the regulation exerted by TSH on thymosin beta10 expression in thyroid follicular cells both in vivo and in vitro.
  
  
  METHODS
  To this aim, we have used 5 bioptic specimens from patients affected by thyroid goiter, a well known experimental model of thyroid goitrogenesis (rat fed with the drug propylthiouracil) and a cultured rat thyroid cell line (PC Cl 3 cells) as a model system.
  
  
  RESULTS
  We report that the mRNA expression of thymosin beta10 is markedly enhanced in human goiters compared with normal thyroid. In vivo results showed that the steady-state level of thymosin beta10 mRNA is up-regulated in the thyroid gland of propylthiouracil-fed rats in parallel with follicular cell proliferation: iodide administration to goitrous rats, which induced a marked involution of thyroid hyperplasia, reduced the mRNA level of thymosin beta10. Finally, in vitro studies showed that in cultured rat thyrocytes, the expression of thymosin beta10 mRNA is induced in a time- and dose-dependent manner by the activation of pathways which are mitogenic for thyroid cells (i.e. the protein kinase (PK) A and PKC pathways).
  
  
  CONCLUSIONS
  Taken together, the findings reported here demonstrate that thymosin beta10 expression is regulated by extracellular signals that stimulate growth of thyroid cells both in vitro and in vivo, and suggest a role for this protein in thyroid diseases characterized by proliferation of follicular cells.
authors.affiliation: Istituto Nazionale dei Tumori di Napoli, Fondazione Senatore Pascale, Via M. Semmola, 80131 Napoli, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Viglietto
authors.forename: D
authors.initials: D
authors.lastname: Califano
authors.forename: P
authors.initials: P
authors.lastname: Bruni
authors.forename: G
authors.initials: G
authors.lastname: Baldassarre
authors.forename: M T
authors.initials: MT
authors.lastname: Vento
authors.forename: B
authors.initials: B
authors.lastname: Belletti
authors.forename: M
authors.initials: M
authors.lastname: Fedele
authors.forename: G
authors.initials: G
authors.lastname: Santelli
authors.forename: A
authors.initials: A
authors.lastname: Boccia
authors.forename: G
authors.initials: G
authors.lastname: Manzo
authors.forename: M
authors.initials: M
authors.lastname: Santoro
authors.forename: A
authors.initials: A
authors.lastname: Fusco
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D006042:Goiter / Q000235:genetics*; D006801:Humans; D007454:Iodides / Q000008:administration & dosage; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D015398:Signal Transduction; D013947:Thymosin / Q000235:genetics*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013972:Thyrotropin / Q000494:pharmacology*
chemical_list: D007454:Iodides; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D013947:Thymosin; C039302:thymosin beta(10); D013972:Thyrotropin