Endothelial cell biomechanical adaptation to altered connexin 43 expression under fluid shear stress

We examined how pharmacological modulation of connexin 43 (Cx43) regulates endothelial biomechanics under static conditions and laminar fluid shear stress (FSS). Cx43 activity was either inhibited with 2',5'-dihydroxychalcone (chalcone) or enhanced with retinoic acid (RA), and biomechanical responses were quantified by measuring tractions, intercellular stress, and cell velocity. Low-dose chalcone increased tractions and intercellular stresses under both static and FSS conditions, whereas high-dose chalcone attenuated these stresses. In contrast, low-dose RA reduced tractions and intercellular stresses under static conditions but enhanced them under FSS, while high-dose RA consistently suppressed mechanical stresses. Chalcone treatment caused dose-dependent reductions in f-actin stress fibers and a reduction in gap junction intercellular communication (GJIC). RA treatment preserved actin organization and increased GJIC up to a threshold concentration, beyond which GJIC declined. Together, these findings demonstrate that Cx43 may regulate endothelial biomechanics in a dose-dependent and flow-dependent manner, supporting a role for gap junctions in endothelial mechanoadaptation to fluid shear stress.