REGULATION OF SECRETORY CAPACITY IN SPECIALIZED SECRETORY CELLS

GARCIA IA; MARTINEZ, H; SAMPIERI, L; ALVAREZ, C

Rosario, Santa Fe

Exposición; SAIB 2014; 2014

SAIB

Secretion occurs in all cells, with relatively low levels in most cells and extremely high levels in specialized secretory cells. Although the molecular machinery involved in the secretory pathway is well studied, how secretory capacity is selectively upregulated in specialized secretory cells is not clearly understood. It has been demonstrated that CREB3 proteins, which are ER-localized bZip transcription factors, upregulate genes involved in secretory capacity and increased secretion of specific cargos. However, how changes in secretory capacity are coordinated to allow an efficient 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 adaptation to a higher secretory demand. We showed that TSH stimulation enhances the level of proteins required for membrane transport 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, to maintain 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.