Dynamic cytosolic foci of DPPA4 in human pluripotent stem cells.

ABSTRACT

DPPA4 is essential for the pluripotent stem cell state, yet its function is poorly understood. DPPA4 is localized in the nucleus, where it is associated with active chromatin. We now report that it is also present in the cytosol, where it appears as diffused clouds, distinct foci and sometimes as spaghetti-like structures. This cytosolic localization is dynamic and DPPA4 shuttles between the cytosol and the nucleus. Its presence is almost abolished from the nucleus upon differentiation. Co-immunoprecipitation studies highlighted novel protein interactors, many of which are also found in the cytosol and are implicated in mRNA processing and RNA and protein transport between the cytosol and the nucleus. Finally, the depletion of DPPA4 resulted in cytosolic accumulation of vesicles. The cytosolic presence of DPPA4 highlights unexplored research directions that could significantly advance the understanding of DPPA4 in pluripotent stem cells and in cancer.