Retinoic Acid-Induced Protein 14 (RAI14) Promotes mTOR-Mediated Inflammation Under Inflammatory Stress and Chemical Hypoxia in a U87 Glioblastoma Cell Line
Retinoic acid-induced 14 is a developmentally regulated gene induced by retinoic acid and is closely associated with NIK/NF-κB signaling. In the present study, we examined the effect of RAI14 on mTOR-mediated glial inflammation in response to inflammatory factors and chemical ischemia. A U87 cell model of LPS- and TNF-α-induced inflammation was used to investigate the role of RAI14 in glial inflammation. U87 cells were treated with siR-RAI14 or everolimus to detect the correlation between mTOR, RAI14, and NF-κB. CoCl2-stimulated U87 cells were used to analyze the effect of RAI14 on mTOR-mediated NF-κB inflammatory signaling under chemical hypoxia. LPS and TNF-α stimulation resulted in the upregulation of RAI14 mRNA and protein levels in a dose- and time-dependent manner. RAI14 knockdown significantly attenuated the level of pro-inflammatory cytokine via inhibiting the IKK/NF-κB pathway. Treatment with an mTOR inhibitor (everolimus) ameliorated NF-κB activity and IKKα/β phosphorylation via RAI14 signaling. Notably, RAI14 also enhanced mTOR-mediated NF-κB activation under conditions of chemical hypoxia. These findings provide significant insight into the role of RAI14 in mTOR-induced glial inflammation, which is closely associated with infection and ischemia stimuli. Thus, RAI14 may be a potential drug target for the treatment of inflammatory diseases.
KeywordsRAI14 Neuroinflmamation mTOR NF-κB Chemical hypoxia
Eukaryotic initiation factor 4E binding protein1
Central nervous system
Eukaryotic translational initiation factor 4 epsilon
NF-kappa-B inhibitor alpha
Nuclear factor NF-kappa-B inhibitor kinase
Mammalian target of rapamycin
Mammalian target of rapamycin complex
Nuclear factor kappa-light-chain-enhancer of activated B cells
Pathogen-associated molecular patterns
Retinoic acid-induced protein 14
Regulatory-associated protein of mTOR
Quantitative real-time polymerase chain reaction
Small interfering RNA
In this study, JG conceived the general idea. XGS, JRZ, XLZ, YFW, and YFH carried out experiments. XGS, and JG analyzed and interpreted the data and wrote the paper. JG critically reviewed and edited the work. All authors approved the final version of the manuscript.
This work was supported by Grants from the National Natural Science Foundation of China (81573409) and Natural Science Foundation of Jiangsu Province (BK20161574) and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (Integration of Raditional Chinese and Western Medicine).
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors. The manuscript does not contain clinical studies or patient data.
- Caccamo A, Belfiore R, Oddo S (2018) Genetically reducing mTOR signaling rescues central insulin dysregulation in a mouse model of Alzheimer’s disease. Neurobiol Aging 68:59–67. https://doi.org/10.1016/j.neurobiolaging.2018.03.032 CrossRefPubMedGoogle Scholar
- Han R, Gao J, Zhai H, Xiao J, Ding Y, Hao J (2016) RAD001 (everolimus) attenuates experimental autoimmune neuritis by inhibiting the mTOR pathway, elevating Akt activity and polarizing M2 macrophages. Exp Neurol 280:106–114. https://doi.org/10.1016/j.expneurol.2016.04.005 CrossRefPubMedGoogle Scholar
- Liu Y et al (2017) Peripheral immune tolerance alleviates the intracranial lipopolysaccharide injection-induced neuroinflammation and protects the dopaminergic neurons from neuroinflammation-related neurotoxicity. J Neuroinflamm 14:223. https://doi.org/10.1186/s12974-017-0994-3 CrossRefGoogle Scholar
- Subhan F et al (2017) Fish scale collagen peptides protect against CoCl2/TNF-alpha-induced cytotoxicity and inflammation via inhibition of ROS, MAPK, and NF-kappaB pathways in HaCaT cells. Oxid Med Cell Longev 2017:9703609. https://doi.org/10.1155/2017/9703609 CrossRefPubMedPubMedCentralGoogle Scholar