2008 Rustbelt RNA Meeting
The PMR1 mRNA endonuclease catalyzes the selective decay of a limited number of mRNAs. It participates in multiple complexes, including one containing c-Src, its activating kinase, and one containing its substrate mRNA. We used tandem affinity (TAP) chromatography to identify proteins in HeLa cell S100 associated with the mature 60 kDa form of Xenopus PMR1 (xPMR60). Unexpectedly this identified a number of cytoskeleton-associated proteins, most notably the Ena family proteins mammalian Enabled (Mena) and vasodilator stimulated phosphoprotein (VASP). These are regulators of actin dynamics that are concentrated at the leading edge in lamellepodia. We show that only a portion of xPMR60 interacts with Mena and VASP in vivo, and that this interaction is independent of the cytoskeleton and RNA. Mena interacts with both c-Src and xPMR60 and sediments with xPMR60 on glycerol gradients in the functional complex containing xPMR60 and its substrate mRNA. To address the function of the xPMR60-Mena interaction, wound healing experiments were performed and showed that cells expressing xPM60R have a more invasive phenotype than those not expressing xPMR60. Confocal microscopy was used to look at the interaction of PMR, actin and VASP in cells. Our results point to an interaction of xPMR60 with the Ena family proteins that localizes the decay of specific mRNAs at the leading edge of the cell.
Keywords: PMR, cytoskeleton-associated proteins