REGULATION OF SECRETORY CAPACITY IN SPECIALIZED SECRETORY CELLS

GARCÍA IA; MARTINEZ HE; SAMPIERI L; ALVAREZ CI

Rosario

Congreso; L Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretorycells. Although the molecular machinery involved in the secretory pathway is well studied, how secretory capacity isselectively upregulated in specialized secretory cells is not clearly understood. It has been demonstrated that CREB3proteins, which are ER-localized bZip transcription factors, upregulate genes involved in secretory capacity andincreased secretion of specific cargos. However, how changes in secretory capacity are coordinated to allow anefficient transport process are not well known. Using a thyroid cell line, in which thyroid-stimulating hormone (TSH)stimulates the synthesis of thyroid specific proteins, we analyzed the mechanisms that are involved in the adaptationto a higher secretory demand. We showed that TSH stimulation enhances the level of proteins required for membranetransport and ER folding (chaperones), as well as the Golgi volume, in agreement with an increase in specific cargolevels. Furthermore, we showed that one member of the CREB3 family is regulated by TSH. Our data indicate that, tomaintain cellular homeostasis after stimulation, a global cell response is induced to cope with cargo increase,suggesting that common signaling pathways are able to modulate specific secretory production and traffic-relatedgenes