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Molecular basis involved in the regulation of sodium-iodide symporter (NIS) expression by iodide in thyrocytes.

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Author(s):
Caroline Serrano do Nascimento
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
Defense date:
Examining board members:
Maria Tereza Nunes; Denise Pires de Carvalho; Edna Teruko Kimura; Anselmo Sigari Moriscot; Ileana Gabriela Sanchez de Rubio
Advisor: Maria Tereza Nunes
Abstract

Iodide reduces NIS mRNA expression, poly(A) tail length and transcription rate, after 30 min of treatment. The present study aimed to caracterize the molecular basis involved in these inhibitory effects. PCCl3 cells were treated with NaI (10-3M) and assays were performed to evaluate: NIS transcript half-life; the role of NIS mRNA 3\'UTR/5\'UTR; the involvement of transcriptional events; the organization of actin cytoskeleton; the total content, half-life, degradation, internalization and activity of NIS; the activation of PI3K/Akt pathaway. The results indicatred that iodide excess: reduces NIS transcript half-life and interacts with its 3\'UTR portion; inhibits NIS promoter activity; disrupts the actin cytoskeleton; reduces NIS total and membrane content, NIS half-life and NIS activity; induces the internalization of NIS through clathrin and its degradation through lisosomes; activates the PI3K/Akt pathway. In conclusion, iodide activates different molecular mechanisms, transcriptional and post-transcriptional, to promoter the inhibitory effect on NIS expression. (AU)