DDX6 Helicase Behavior and Protein Partners in Human Adipose Tissue-Derived Stem Cells during Early Adipogenesis and Osteogenesis.

DDX6 helicase is an RNA-binding protein involved in different aspects of gene expression regulation. The roles played by DDX6 depend on the complexes associated with it. Here, for the first time, we characterize the protein complexes associated with DDX6 in human adipose tissue-derived stem cells (hASCs) and analyze the dynamics of this helicase under different conditions of translational activity and differentiation. The results obtained demonstrated that the DDX6 helicase is associated with proteins involved in the control of mRNA localization, translation and metabolism in hASCs. DDX6 complexes may also assemble into more complex structures, such as RNA-dependent granules, the abundance and composition of which change upon inhibited translational activity. This finding supports the supposition that DDX6 is possibly involved in the regulation of the mRNA life cycle in hASCs. Although there was no significant variation in the protein composition of these complexes during early adipogenic or osteogenic induction, there was a change in the distribution pattern of DDX6: the number of DDX6 granules per cell was reduced during adipogenesis and was enhanced during osteogenesis.