Activation of PDK1 mediates VSMC migration and may contribute to vascular remodeling following injury

Abstract

We hypothesized that increased 3‐phosphoinositide‐dependent kinase 1 (PDK1) activation contributes to arterial wall thickening following vascular injury. Vascular smooth muscle cells (VSMCs) were pretreated with BX‐912, a small molecule inhibitor of PDK1, prior to stimulation with PDGF. Western analysis confirmed inhibition of PDK1 activity in the presence of BX‐912 by decreased phosphorylation of PDK1 (ser241) by ~60% and Akt (thr308) by ~ 70%. Conversely, Akt phosphorylation at ser473 was only mildly affected. To examine VSMC migration, both scratch wound assays and modified Boyden chamber studies were completed. In both instances, wound‐ and PDGF‐induced chemotaxis was attenuated following BX‐912 treatment. Following wire injury of the carotid artery in C57BL6/J mice, in vivo PDK1 phosphorylation (ser 241) was assessed by immunoblotting in both injured and contralateral control carotids at 3, 7, and 14 days post injury. PDK1 phosphorylation was markedly increased at day 3 (~5 fold vs. non‐injured), remained slightly elevated at day 7 (~2 fold) and returned close to baseline by later timepoints following injury. Our findings indicate that BX‐912 is effective in attenuating PDK1 activity and chemotaxis in VSMCs and that increased PDK1 activity occurs following vascular injury. Thus, PDK1 inhibition, via BX‐912 treatment, could potentially be utilized to attenuate wall remodeling in response to injury. Support: NIH HL084159