Phosphorylation of GMFγ by c-Abl coordinates lamellipodial and focal adhesion dynamics to regulate airway smooth muscle cell migration.pdf

<div>Airway smooth muscle cells require coordinated protrusion and focal adhesion dynamics to</div><div>migrate properly. However, the signaling cascades that connect these two processes remain</div><div>incompletely understood. GMFγ has been implicated in inducing actin debranching and inhibiting</div><div>nucleation. In this study, we discovered that GMFγ phosphorylation at Y104 regulates human</div><div>airway smooth muscle cell migration. Utilizing high-resolution microscopy coupled with 3D-object</div><div>based quantitative image analysis software Imaris 9.2.0, phosphomimetic mutant Y104D-GMFγ</div><div>was enriched at nascent adhesions along the leading edge where it recruited activated N-WASP</div><div>(pY256) to promote actin-branch formation, which enhanced lamellipodial dynamics and limited</div><div>the growth of focal adhesions. Unexpectedly, we found that non-phosphorylated mutant Y104FGMFγ</div><div>was enriched in growing adhesions where it promoted a linear branch organization, focal</div><div>adhesion clustering, and recruited zyxin to increase maturation, thus inhibiting lamellipodial</div><div>dynamics and cell migration. The localization of GMFγ between the leading edge and focal</div><div>adhesions was dependent upon myosin activity. Furthermore, c-Abl tyrosine kinase regulated the</div><div>GMFγ phosphorylation-dependent processes. Together, these results unveil the importance of</div><div>GMFγ phosphorylation in coordinating lamellipodial and focal adhesion dynamics to regulate cell</div><div>migration.</div>