Novel aspects of T-3 actions on GH and TSH synthesis and secretion: physiological implications

Author(s)

Bargi-Souza, P. ^[1] ; Goulart-Silva, F. ^[1] ; Nunes, M. T. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, Sao Paulo, SP - Brazil

• Document type: Review article
• Source: JOURNAL OF MOLECULAR ENDOCRINOLOGY; v. 59, n. 4, p. R166-R177, NOV 2017.
• Web of Science Citations: 4

Abstract

Thyroid hormones (THs) classically regulate the gene expression by transcriptional mechanisms. In pituitary, the encoding genes for growth hormone (GH) and thyroid-stimulating hormone (TSH) are examples of genes regulated by triiodothyronine (T-3) in a positive and negative way, respectively. Recent studies have shown a rapid adjustment of GH and TSH synthesis/secretion induced by T-3 posttranscriptional actions. In somatotrophs, T-3 promotes an increase in Gh mRNA content, poly(A) tail length and binding to the ribosome, associated with a rearrangement of actin cytoskeleton. In thyrotrophs, T-3 reduces Tshb mRNA content, poly(A) tail length and its association with the ribosome. In parallel, it promotes a redistribution of TSH secretory granules to more distal regions of the cell periphery, indicating a rapid effect of T-3 inhibition of TSH secretion. T-3 was shown to affect the content of tubulin and the polymerization of actin and tubulin cytoskeletons in the whole anterior pituitary gland, and to increase intracellular alpha (CGA) content. This review summarizes genomic and non-genomic/posttranscriptional actions of TH on the regulation of several steps of GH and TSH synthesis and secretion. These distinct mechanisms induced by T-3 can occur simultaneously, even though non-genomic effects are promptly elicited and precede the genomic actions, coexisting in a functional network within the cells. (AU)

• FAPESP's process: 09/17813-9 - Rapid actions of Triiodothyronine (T3) on TSH expression and secretion: new mechanisms involved in the negative feedback.
• Grantee: Paula Bargi de Souza
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/05629-4 - Genomic vs nongenomic actions of thyroid hormones: changes of paradigms, physiological implications and therapeutical perspectives
• Grantee: Maria Tereza Nunes
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 14/25888-7 - Characterization of the molecular basis involved on the expression of circadian clock genes in the pituitary at different thyroid states and the consequences for the synthesis/secretion of anterior pituitary hormones
• Grantee: Paula Bargi de Souza
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 12/06643-8 - Rapid actions of triiodothyronine (T3) on intracellular calcium and membrane potential of thyrotrophs and implications on TSH secretion
• Grantee: Paula Bargi de Souza
• Support type: Scholarships abroad - Research Internship - Doctorate