Gene expression, function, and diversity of Nkx2-4 in the rainbow trout, Oncorhynchus mykiss.
Gen Comp Endocrinol
; 206: 193-202, 2014 Sep 15.
Article
en En
| MEDLINE
| ID: mdl-25051213
ABSTRACT
Nkx2 homeodomain transcription factors are involved in various developmental processes and cell specification e.g. in mammals, NKX2-1 is essential for thyroid-specific gene expression and thyroid morphogenesis. Among Nkx2 proteins, information is still very limited for Nkx2-4. In the present study, we have identified three distinct cDNAs encoding Nkx2-4 isoforms (Nkx2-4a, -b, and -c) from the rainbow trout thyroid tissue, and characterized their transcriptional properties. The trout Nkx2-4 proteins were all predicted to conserve three characteristic domains the tinman-like amino terminal decapeptide, the NK2 homeodomain, and the NK2-specific domain, and also share 75-89% amino acid similarity. It was shown by dual luciferase assay that Nkx2-4a and Nkx2-4b, but not Nkx2-4c, significantly activated transcription from a cotransfected rat thyroglobulin (TG) promoter. An electrophoretic mobility shift assay indicated that all the Nkx2-4 isoforms could bind to the TG promoter, implying that the faint transcriptional activity of Nkx2-4c might result from some critical amino acid substitution(s) outside the homeodomain. RT-PCR analysis revealed similar tissue distribution patterns for Nkx2-4a and Nkx2-4b mRNAs. Both mRNAs were expressed abundantly in the thyroid, and weakly in the testis. On the other hand, Nkx2-4c mRNA was detected in the ovary as well as in the thyroid. The expression sites of Nkx2-4c mRNA were localized, by in situ hybridization histochemistry, to the ovarian granulosa cells and to the thyroid follicular cells. The results suggest that in the rainbow trout, Nkx2-4a and Nkx2-4b might play a major role in TG gene transcription whereas Nkx2-4c might have some functions in the ovary as well as the thyroid.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Factores de Transcripción
/
Proteínas Nucleares
/
Regulación de la Expresión Génica
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Gen Comp Endocrinol
Año:
2014
Tipo del documento:
Article
País de afiliación:
Japón