Circadian regulation of mRNA granules

GARBARINO PICO E; GUIDO ME

Congreso; L Reunión Anual - SAIB; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Stress granules (SGs) and Processing bodies (PBs) are microscopically visible foci formed by mRNAs, translation factors, RNA-binding proteins, and other proteins involved in the processing of messengers in the cytoplasm. SGs and PBs are intimately related to mRNA translation, degradation and storage. Since a number of P-body and SG components display circadian rhythms, we hypothesized that these mRNA granules could be temporarily regulated. We analyzed PBs and SGs by ICC with anti-GE-1/hedls and anti-eIF3 antibodies respectively, in synchronized NIH3T3 cell cultures. We found that both SGs as PBs display circadian changes in number. We found no changes in phosphorylated eIF2alpha, a protein involved in SG assembly. Then we analyzed by RT-qPCR the temporal expression of the mRNAs of several RNA-binding proteins that are in RNA granules and could be involved in the temporal changes observed. Interesting, Tia1, Brf1, hnRNPQ, and Lark transcripts presented temporal changes in their levels. TIA1 protein has been implicated in SG assembly; we found that its levels also oscillate. LARK, which regulates the translation of the clock protein PER1, also presented temporal variations in its induction by stress. Our results show that PBs and SGs are temporarily regulated and that SGs may be involved in the circadian regulation of stress response.