Circadian Regulation of cytoplasmic RNA granules

PUSTERLA JM; LESCANO JI; GARBARINO PICO E

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

SAIB

About 5-20% of the mRNAs expressed in a given tissue show daily oscillations in their levels. Presumably, this is largely generated by changes in the transcription of those genes; however, the contribution of mRNA posttranscriptional processing is unknown. In the cytoplasm, messenger ribonucleoprotein (mRNP) complexes can assemble into cytoplasmic mRNP granules as Pbodies and stress granules (SG). These foci are involved in the regulation of mRNA decay and storage, as well as translation. They are formed by RNA and a number of factors involved in mRNA processing. We have analyzed whether these foci show rhythmicchanges. NIH3T3 cells were synchronized by serum shock. SG and P-bodies were detected at different times by immunocytochemistry (ICC) with antibodies against eIF3 and GE-1 respectively. P-body per cell (number) showed fluctuations peaking 28 h after synchronization and reaching highest areas 14 h after the shock. The number of arsenite-induced SG/cell did not change through time; however the area and perimeter of them showed daily variations with peak 14 h after serum shock. These rhythms are independent of the cell cycle since were observed in quiescent cells. We have also analyzed the temporal expression of several factors that could be responsible of the generation of these rhythms. Our results suggest that P-bodies and SGs, or a subpopulation of them, are regulated by a circadian clock.