Circadian regulation of cytoplasmic mRNA-granules

LESCANO JI; GUIDO ME; GARBARINO PICO E

Congreso; XI Latin American Symposium on Chronobiology; 2011

Gene expression is modulated by clocks, 5-20% of the mRNAs expressed in a given tissue show daily oscillations. Presumably, this is largely generated by changes in the transcription of those genes; however, the relative importance of mRNA post-transcriptional processing has not been established. Stress granules (SG) and P-bodies are cytoplasmic subdomains involved in the regulation of translation, mRNA decay and storage. They are formed by RNA and a number of factors involved in mRNA cytoplasmic processing. Considering that some of the SG and P-body components are expressed under circadian basis, we have analyzed whether these foci show rhythmic changes. NIH3T3 cells were synchronized by serum shock and fixed at different times. SG and P-bodies were detected by ICC. P-body per cell (number) showed fluctuations peaking 28 h after synchronization, and reaching highest areas 14 h after the shock. We applied arsenite (oxidative stress) for inducing SG. The number of SG/cell did not change through time; however the area and perimeter of them showed daily variations with peak 14 h after serum shock. Further studies will be carried out with other markers to confirm these results; however they suggest that these foci, or a subpopulation of them, are regulated by a circadian clock.