Spatial regulation of mitochondrial membrane potential by α5β1 integrin engagement in collective cell migration.

The mechanistic links between mechanical forces and bioenergetics remain elusive. We report an increase in mitochondrial membrane potential (MMP) along the leading row of collectively migrating Xenopus laevis mesendoderm cells at sites where fibronectin-α5β1 integrin substrate traction stresses are greatest. Real-time metabolic analyses reveal α5β1 integrin-dependent increases in respiration efficiency in cells on fibronectin substrates. Elevation of metabolic activity is reduced following pharmacologic inhibition of focal adhesion kinase (FAK; also known as PTK2) signaling. Attachment of mesendoderm cells to fibronectin fragments that support differing α5β1 integrin conformational and ligand-binding affinity states, increases MMP when both the Arg-Gly-Asp (RGD) and Pro-Pro-Ser-Arg-Asn (PPSRN) synergy sites of fibronectin are engaged by the receptor. Cell stretch on deformable fibronectin substrates also results in a FAK-dependent increase in MMP. Inhibition of MMP or ATP-synthase activity slows collective cell migration velocity in vivo, further suggesting that integrin-dependent adhesion and signaling contribute to metabolic changes. These data highlight an underexplored link between extracellular matrix (ECM)-integrin adhesion and metabolic activity in embryonic cell migration. We propose that fibronectin-integrin adhesion and signaling help shape the metabolic landscape of collectively migrating cells.