Cerebral dopamine neurotrophic factor protects microglia by combining with AKT and by regulating FoxO1/mTOR signaling during neuroinflammation

Abstract

Background: The activation of microglia plays a crucial role in neuroinflammation. Previous studies have shown that cerebral dopamine neurotrophic factor (CDNF) has a protective effect on neuroinflammation, but the mechanisms involved have not been fully studied. AKT is a serine-threonine protein kinase widely expressed in mammals through which the downstream pathway FoxO1/mTOR is closely related to cell inflammation, apoptosis, metabolism, etc. Therefore, we examined whether CDNF regulates neuroinflammation through this pathway. Methods: After pretreatment with CDNF and LPS, microglial cells were detected by laser confocal microscopy, coimmunoprecipitation and immunofluorescence to observe whether CDNF was colocalized with AKT. The expression of AKT and its downstream FoxO1/mTOR were determined by Western blot. The effect of CDNF on inflammatory cytokines was detected by ELISA, and the mRNA levels of AKT and FoxO1/mTOR were detected by qRT-PCR. Results: Laser confocal and coimmunoprecipitation experiments significantly reveal the occurrence of interactions between AKT and CDNF in microglia. Western blot results show that CDNF incubation suppressed the activation of AKT/FoxO1/mTOR signaling. Moreover, CDNF clearly decreased the expression of inflammatory cytokines. In qRT-PCR, the expression of mRNA in AKT and its downstream FoxO1/mTOR gradually decreased due to CDNF intervention. Conclusions: CDNF combined with AKT and regulated the downstream pathway FoxO1/mTOR in microglia, eventually suppressing the secretion of inflammatory factors. Therefore, CDNF might play a protective role in the neuroinflammation of microglia via AKT/FoxO1/mTOR signaling.