Insulin and insulin-like growth factor I regulate a thyroid-specific nuclear protein that binds to the thyroglobulin promoter.
Mol Endocrinol
; 6(8): 1310-7, 1992 Aug.
Article
em En
| MEDLINE
| ID: mdl-1406708
ABSTRACT
The mechanism responsible for the stimulation of thyroglobulin (Tg) gene expression by insulin and insulin-like growth factor I (IGF-I) in rat thyroid FRTL-5 cells has been investigated. Both insulin and IGF-I stimulate transcription from the Tg promoter in a transient transfection assay demonstrating that the promoter used contains the DNA signals necessary for insulin and IGF-I regulation. Promoter mutations that interfere with the binding of thyroid transcription factor 1 (TTF-1), TTF-2, and the ubiquitous transcription factor abolish the insulin/IGF-I response, indicating that the three factors may be involved in the observed transcriptional control. Protein-DNA binding studies did not reveal any effect of insulin/IGF-I on the ubiquitous transcription factor and the TTF-1 binding capacity. Instead, TTF-2 is absent in nuclear extracts from cells depleted of serum and insulin. Addition of insulin or IGF-I restores the TTF-2 concentration to normal levels and requires ongoing protein synthesis. The insulin effect was maximal at 24 h and at a concentration of 1 microgram/ml. The same effect was observed with a 10-fold lower concentration of IGF-I. These results suggest that insulin (probably through the IGF-I receptor) and IGF-I modulate the levels of TTF-2, which results in an increased expression of the Tg gene.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tireoglobulina
/
Glândula Tireoide
/
Fator de Crescimento Insulin-Like I
/
Proteínas Nucleares
/
Regiões Promotoras Genéticas
/
Proteínas de Ligação a DNA
/
Insulina
Limite:
Animals
Idioma:
En
Revista:
Mol Endocrinol
Assunto da revista:
BIOLOGIA MOLECULAR
/
ENDOCRINOLOGIA
Ano de publicação:
1992
Tipo de documento:
Article
País de afiliação:
Espanha