Temporal regulation of Stress Granules by circadian clocks and redox oscillations

MALCOLM MELISA; RÍOS MAXIMILIANO; SAAD LUCIA FLORENCIA; GUIDO MARIO EDUARDO; GARBARINO PICO EDUARDO

Córdoba

Congreso; SAIB. LII Reunión Anual. Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2016

Stress granules (SGs) are microscopically visible foci formed by assemblies of untranslating messenger ribonucleoproteins that form in response to stress from mRNAs stalled in translation initiation. Since a number of SG components display circadian rhythms, we had hypothesized that these mRNA granules could be circadianly regulated. Indeed, we have previously shown that SGs induced by oxidative stress display daily changes in their number and size in synchronized NIH3T3 cultures. In order to establish whether the oscillations observed were truly circadian rhythms, we carried out similar experiments in clock defective cells. We utilized fibroblasts from knockout or double knockout mice for different clock genes: Bmal1, Per1/2 and Cry1/2 and their corresponding wt controls. In all cases we found significant changes through time in the number, area, and signal intensity of eIF3 immunolabeled SGs in synchronized cultures. However the period, amplitude, and phase of the oscillations were different in each genotype. Since these parameters are altered in cells without a functional circadian clock, we concluded that the described oscillations are modulated by this timing mechanism but also for some other metabolic rhythm. It has been reported redox rhythms in several systems independently of the canonical clock, thus we presume that they could be responsible of the oscillations we found.