GARBARINO PICO EDUARDO
Congresos y reuniones científicas
Título:
Processing body and stress granule rhythms in cell cultures.
Autor/es:
MALCOLM M; PENAZZI LG; GARBARINO PICO E
Lugar:
Buenos Aires (VIRTUAL)
Reunión:
Simposio; XVI Latin American Symposium on Chronobiology (LASC); 2021
Resumen:
Stress granules (SGs) and processing bodies (PBs) are membraneless organelles that are formed by liquid-liquid phase transitions in the cytoplasm. They are involved in the regulation of translation, stability and storage of mRNA. These biocondensates share some components such as mRNA and several RNA binding proteins. SGs contain translation initiation factors, the minor subunit of the ribosome (40S) and translation stalled mRNAs. They form in response to different stress stimuli, typically through phosphorylation of the eIF2alpha. PBs, on the other hand, are enriched in factors involved in mRNA degradation, translational repression and RNA-mediated silencing. They are constitutively present, depending on the cell type, although they increase in number under stress conditions. Since stress response has been shown to be circadianly regulated in several models, we wonder whether SGs and PBs oscillate. NIH/3T3 and N2a neuroblastoma cell cultures were synchronized with dexamethasone and harvested every 4 h for 68 h. We induced the formation of SGs with sodium arsenite (oxidative stress). We performed a double immunolabeling of SGs (eIF3 and G3BP1) and PB (GE-1/HEDLS and DDX6) by immunocytochemistry. We also studied the phosphorylation temporal profile of eIF2alpha and eIF3 levels. We observed that NIH/3T3 and N2A cells show daily rhythms in SGs and PBs, respectively, for three variables: number, area, and signal intensity, with the estimated parameters showing periods of approximately 24 h. We found no differences in eIF3 and eIF2α phosphorylation levels over time, thus, they would not be responsible for generating the changes observed in SGs. These findings strongly suggest that the molecular circadian clock controls SGs and PBs. To determine this hypothesis, we analyzed their formation in Bmal1-/- fibroblasts. Surprisingly, the rhythm persisted in these cells. The results presented here reveal new ways in which translation and cytoplasmic mRNA metabolism can be modulated over time. Further studies are needed to demonstrate whether the SG rhythms observed Bmal1-/- cells are true circadian rhythms.
