Abstract 14861: Dual Mode Regulation of Directional Cell Migration by AMPK Using Two Substrates With Distinct Kinetics

Abstract

Introduction: Striking feature of the regulation of cell migration by AMP-activated protein kinase (AMPK) activity level is that both suppression and augmentation of AMPK inhibit cell migration. Hypothesis: We have previously revealed that AMPK inhibition perturbs cell migration through the destabilisation of the microtubule cytoskeleton via de-phosphorylation of the microtubule plus-end protein CLIP-170. However, the mechanism for how AMPK activation also perturbs cell migration still remains unknown. Methods and Results: Here we used LC/MS to identify a novel substrate of AMPK: PDZ and LIM domain 5 (PDLIM5) is specifically phosphorylated only when AMPK activity is increased. Vascular smooth muscle cells expressing the phosphomimetic PDLIM5 mutant showed perturbed cell migrations accompanied by enlarged focal adhesions and enhanced stress fibre formation without disturbing the microtubule structures. Interestingly, the phosphorylation of PDLIM5 reduced its affinity for α-actinin, which may mechanistically contribute to actin cytoskeleton reorganisation and consequentially the inhibition of cell migration. Conclusions: We proposed the dual mode model, which regulates the directional cell migration of AMPK using the two substrates CLIP-170 and PDLIM5, with distinct activation kinetics to regulate cell migration separately by sensing the level of AMPK activity between two extremes.