Stress granules and Processing bodies oscillate in mammalian fibroblasts

MALCOLM MELISA; SAAD LUCÍA FLORENCIA; GARBARINO PICO EDUARDO

Córdoba

Congreso; XXXIII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

Sociedad Argentina de Investigación en Neurosciencias

Stress granules (SG) and Processing bodies (PB) are cytoplasmic membraneless organelles in which mRNA and mRNA-binding proteins are stored. SGs are formed by translational machinery components, like minor ribosomal subunit, and translation initiation factors, and assemble when cells undergoes a stress. PBs are formed by factors involved in mRNA silencing and enzymes involved in mRNA decay. It has been observed that several components of both SGs and PBs are rhythmically expressed, in a circadian fashion. For this reason we hypothesized that these structures oscillates. We show that the number and area of SGs induced by oxidative stress, as well as the PB number, exhibit daily oscillations in NIH3T3 cells. TIA-1, a protein with a prion-like domain that induces SG nucleation, is also expressed rhythmically. To test whether SG temporal changes were controlled by the transcriptional translational feedback loops (TTFLs) that form the molecular circadian clock, we analyzed SGs in wt and Bmal1-/- fibroblasts. Unexpectedly, we found oscillations in the number, area and signal intensity of SGs in both genotypes. The period and phase of the oscillations were similar in both cell lines, but the amplitude was higher in Bmal1-/- cells, suggesting that the TTFLs modulate the strength of the response at different times. We thought that the SG rhythms could be generated by redox or translational rhythms that have been shown previously in Bmal1-/- cells