P-bodies are cytoplasmic foci composed of mRNAs and enzymes involved in mRNA degradation. P-bodies have been found to link to RNA interference and RNA decay mediated by microRNAs (miRNAs) and translational repression. Here, we aim to investigate different effects of overexpressed Dcp1a or GW182 on cytoplasmic aggregates formation and influence on miRNA pathway. Small RNAs were recruited into endogenous foci of P-bodies and aggregates formed by Dcpa1 and GW182 overexpression. However, only overexpressed Dcp1a but not GW182 was colocalized with DDX6, another component of P-bodies and suppressed protein translation. In addition, we investigated the relationship between stress granules and miRNA pathway and found that granules induced by G3BP1 overexpression could recruit small RNAs into the granules and repressed protein translation. As Ago2 is a key component of RNA-induced silencing complex, we also investigated the localization of endogenous Ago2 (edo-Ago2) after Dcp1a and GW182 overexpression, and found that endo-Ago2 did not colocalize with the aggregates induced by overexpression of Dcpla, GW182, and G3BP1. Notably, the ability of miRNA to regulate its target was enhanced by the granules induced by Dcp1a and G3BP1 expression. Our results suggest that overexpressed Dcp1a and GW182 can form different cytoplasmic aggregates and play distinct biological roles in the miRNA pathway.
Keywords: Dcp1a; G3BP1; GW182; P-body; miRNA pathway.