MRNA Profiling Reveals The Potential Mechanism Of TIPE2 In Attenuating Cognitive Deficits In APP/PS1 Mice

Objective:Alzheimer’s disease(AD)is a chronic progressive neurodegenerative disease.In recent years,with the deepening of research,it has been found that chronic neuroinflammation in the brain of patients is important for the pathogenesis and progression of AD.Overexpression of tumor necrosis factor-α(TNFα)-inducible protein 8-like 2(TIPE2),a novel immunoregulatory protein,reverses cognitive dysfunction in APP/PS1 mice.However,the mRNA profile changes in TIPE2overexpression APP/PS1 mice and the molecular mechanism of cognitive attenuation remain unknown.In this study,after the Y-maze testing the short-term spatial learning of the APP/PS1 mice and the TIPE2 overexpression APP/PS1 mice,RNA sequencing with reference genome was performed on hippocampus tissues and analyzed the genes.We hope to find out molecular expression profiles and signaling pathways related to the improvement of cognitive dysfunction by TIPE2 in the hippocampus.Methods:Groups:TIPE2 over-expressed APP/PS1 mice(APP/PS1+OE),APP/PS1 mice without TIPE2 overexpression(APP/PS1+NC),APP/PS1 mice and wild-type(WT)mice.1.Brain stereotactic injection of adeno-associated cirus(AAV)overexpressed TIPE2in bilateral hippocampus of 7~thh month APP/PS1 mice.Control APP/PS1 mice of the same age were injected with the same dose of the AAV without TIPE2.2.The Y-maze spontaneous alternation experiment was used to assess the short-term spatial learning and memory of the WT mice,APP/PS1+NC mice and TIPE2+OE mice at 0,1,2,3 and 3.5 months after the injection of AAV.3.At 3.5 months after the injection of AAV,RNA sequencing was performed on APP/PS1+OE mice,APP/PS1+NC mice,wild-type mice,and APP/PS1 mice hippocampus tissues for analysis of mRNA profiles.4.Quantitative real-time RT-PCR(qPCR)was performed to verify differentially expressed genes(DEGs)in the sequencing results.Results:1.After the overexpression of TIPE2 in the 7-month-old APP/PS1 mice,the cognitive function of the transgenic mice was significantly improved compared with the negative control APP/PS1 mice,and this phenomenon continued at least until 3.5months after AAV injection,that is,11 months old.2.On average,80.40%reads were mapped,and the mapping results of each sample indicates that the samples are comparable.3.Between APP/PS1+OE mice and APP/PS1+NC mice in their RPKM values,183DEGs were detected,including 144 up-regulated DEGs and 39 down-regulated DEGs.4.Between the wild-type mice and APP/PS1 mice,214 DEGs were detected,including 91 up-regulated mRNAs and 123 down-regulated mRNAs.5.In the joint analysis of DEGs from APP/PS1+NC vs APP/PS1+OE and DEGs from wild-type vs APP/PS1,20 genes were detected as DEGs in both comparisons.The transcription level of 19 DEGs were reversed after TIPE2 overexpression,among which,18 were up-regulated and 1 was down-regulated by TIPE2.6.We selected Ttr,Lepr,Angptl2,Otx2,Clic6,Clo4a3 and Wfdc for validation by qPCR.The result of qPCR analysis is consistent with the results of mRNA sequencing.Conclusions:The cognitive deficits in APP/PS1 mice could be attenuated by TIPE2 overexpression.Transcriptional sequencing and bioinformatics analysis indicate that the attenuation of cognitive deficits was attributed to the recovery of certain genes.