The novel FKBP51‐Hsp90 interaction inhibitor attenuates high‐fat diet induced cognitive impairment

Abstract Background Obesity increases the risk of several chronic diseases, such as type 2 diabetes mellitus, insulin resistance, and Alzheimer disease. As one of the co‐chaperones of heat shock protein 90 (Hsp90), FK506‐binding protein 51 (FKBP51) is an important regulator of metabolic and cognitive dysfunction. FKBP51 knockout mice are resistant to diet‐induced obesity, exhibit elevated glucose and insulin tolerance and have less endogenous tau. FKBP51 overexpression preserves tau and impairs spatial reversal learning and memory. Our group has identified a new family of FKBP51 inhibitors that can disrupt FKBP51‐Hsp90 interactions. Previous study has shown that our inhibitors can dose‐dependently reduce lipid accumulation in adipocytes differentiated from primary human mesenchymal stem cells and stimulate neurite outgrowth in differentiated neuroblastoma SH‐SY5Y cells. This study aims to investigate the potential roles of our inhibitors on metabolic and cognitive dysfunction in vivo . Methods Pharmacokinetic studies have been performed at first. Plasma and brain samples were collected and analyzed by liquid chromatography‐mass spectrometry. Male C57BL/6J mice were fed either the control or high‐fat diet (HFD) for 4 weeks and then treated with vehicle or inhibitor E8 (20 mg/kg, s.c.) and their respective diets for another 4 weeks. Behaviors, body composition measuremnets by EchoMRI, fasting glucose/insulin detections and glucose/insulin tolerance tests were performed during the last week. Hippocampus was collected for western blot, RNA sequencing and quantitative real‐time PCR analysis. Results After subcutaneous injection, E8 can be quickly absorbed into the blood and penetrate the blood‐brain barrier. In HFD model, E8 can attenuate the impairment of locomotor activity and short‐term memory. But it could neither reduce body weight gain nor improve insulin sensitivity and glucose/insulin tolerance. In the hippocampus, E8 reduces the elevated p‐tau (Ser214)/tau levels induced by HFD but does not show any effects on insulin signaling. It suggests that E8 reverses the behavioral impairments independently of metabolic regulation in vivo . The underlying mechanisms were further investigated by RNA sequencing and quantitative real‐time PCR analysis. Conclusion We showed that inhibiting FKBP51‐Hsp90 interactions with small molecules provides novel therapeutic targets on cognitive dysfunction in obesity.