Reduced cofilin activity as a mechanism contributing to endothelial cell stiffening in type 2 diabetes

An emerging instigator of endothelial dysfunction in type 2 diabetes (T2D) is the stiffening of the cell. Previous reports suggest that polymerization of filamentous actin (F-actin) is a potential mediator of endothelial stiffening. Actin polymerization is limited by active cofilin, an F-actin-severing protein that can be oxidized, leading to its inactivation and loss of severing capability. Yet, whether these mechanisms are implicated in endothelial stiffening in T2D remains unknown. Herein, we report that endothelial cells exposed to plasma from male and female subjects with T2D, and the aortic endothelium of diabetic male mice (<i>db/db</i>), exhibit evidence of increased oxidative stress, F-actin, and stiffness. Furthermore, we show reactive oxygen species, including H₂O₂, are increased in the endothelium of mesenteric arteries isolated from <i>db/db</i> male mice, and that exposure of endothelial cells to H₂O₂ induces F-actin formation. We also demonstrate, in vitro, that cofilin-1 can be oxidized by H₂O₂, leading to reduced F-actin severing activity. Finally, we provide evidence that genetic silencing or pharmacological inhibition of LIM kinase 1, an enzyme that phosphorylates and thus inactivates cofilin, reduces F-actin and cell stiffness. In aggregate, this work supports the inactivation of cofilin as a potential novel mechanism underlying endothelial stiffening in T2D.<b>NEW & NOTEWORTHY</b> Cell stiffening is an emerging contributor to endothelial dysfunction, a classic feature of type 2 diabetes (T2D). However, the mechanisms underlying endothelial stiffening remain largely unknown. This work provides evidence that oxidative stress-induced inactivation of cofilin, a key F-actin severing protein, may be implicated in increasing endothelial F-actin and cell stiffness in T2D.