Rapid actions of triiodothyronine (T3) on TSH expression and secretion: new mechanisms involved in the negative feedback.

Author(s)

Paula Bargi de Souza

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2015-03-11

Examining board members

Maria Tereza Nunes; Maria Luiza Morais Barreto de Chaves; Maria Izabel Chiamolera; Augusto Ducati Luchessi; Ileana Gabriela Sanchez de Rubio

• Advisor: Maria Tereza Nunes

Abstract

The thyrotropin (TSH) is the main regulator of thyroid hormones (HTs) synthesis and secretion, which in turn, exert a negative feedback in the pituitary gland reducing the synthesis of alpha (Cga) and beta (Tshb) TSH subunits by genomic actions. In parallel, some HTs actions are triggered in the presence of inhibitors of gene transcription and in seconds to minutes, featuring the non genomic actions of HTs. The goal of this study was to evaluate the possible non genomic actions of T3 on expression, posttranscriptional regulation, translation and secretion of TSH, as well as, the participation of calcium and magnesium on this process. The results have shown that the T3, interacts with aVb3 integrin, reduces the content of Tshb mRNA even in the presence of gene transcription inhibitor, decreases the poly(A) tail length, the translation rate of this transcript and the secretion through aVb3- and PI3K-dependent mechanisms. The T3 also increases and does not alter the intracellular concentration of magnesium and calcium, respectively. These data demonstrates the existence of an additional and non genomic mechanism by which the T3 interacts with aVb3 integrin and reduces the synthesis/secretion of TSH, in parallel to the control of Tshb and Cga gene transcription. (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 Opportunities: Scholarships in Brazil - Doctorate