Abstract
Insulin signaling is essential for glucose metabolism, and insulin decreases insulin receptor (InsR) levels in a dose-dependent and time-dependent manner. However, the regulatory mechanisms of InsR reduction upon insulin stimulation remain poorly understood. Here, we show that Eph receptor B4 (EphB4), a tyrosine kinase receptor that modulates cell adhesion and migration, can bind directly to InsR, and this interaction is markedly enhanced by insulin. Due to the adaptor protein 2 (Ap2) complex binding motif in EphB4, the interaction of EphB4 and InsR facilitates clathrin-mediated InsR endocytosis and degradation in lysosomes. Hepatic overexpression of EphB4 decreases InsR and increases hepatic and systemic insulin resistance in chow-fed mice, whereas genetic or pharmacological inhibition of EphB4 improve insulin resistance and glucose intolerance in obese mice. These observations elucidate a role for EphB4 in insulin signaling, suggesting that EphB4 might represent a therapeutic target for the treatment of insulin resistance and type 2 diabetes.