Endothelial nitric oxide synthase signaling pathway (eNOS-PI3K-Akt pathway)

The eNOS-PI3K-Akt pathway is a critical signaling axis in the vascular endothelium that regulates the production of nitric oxide (NO), a key mediator of vascular health [1, 9]. The pathway is typically activated by mechanical stimuli like shear stress or chemical agonists such as vascular endothelial growth factor (VEGF) and insulin [1]. These stimuli trigger phosphoinositide 3-kinase (PI3K), which subsequently activates the serine/threonine kinase Akt (Protein Kinase B) [1, 4]. Activated Akt then phosphorylates endothelial nitric oxide synthase (eNOS) at the Ser1177 residue, significantly increasing its enzymatic activity to produce NO from L-arginine [4, 5]. NO diffuses into the underlying smooth muscle cells to induce vasorelaxation and also acts within the vessel lumen to inhibit platelet aggregation and leukocyte adhesion [9, 12]. Dysregulation of this pathway leads to endothelial dysfunction, a precursor to major cardiovascular conditions such as atherosclerosis, hypertension, and diabetic vasculopathy [2, 3]. Many cardiovascular drugs, including statins and ACE inhibitors, exert their beneficial effects in part by upregulating or restoring the activity of this pathway [3, 9].

Other names

eNOS/PI3K/Akt axisPI3K/Akt/eNOS pathwayEndothelial NO synthase pathwayeNOS-PI3K-Akt signaling pathway

The pathway operates through the sequential activation of PI3K and Akt, leading to the phosphorylation of eNOS at the Ser1177 residue, which enhances enzymatic activity and increases nitric oxide production to promote vasodilation and vascular protection [1, 4, 5].