The Mediating Role And Mechanism Of LINGO-1in Aβ Deposition Caused By Sleep Deprivation

Alzheimer’s disease (AD) is a common neurodegenerative disease in the elderly, and isthe most common cause of dementia. Epidemiological studies have discovered that,44%of patients with AD are associated with sleep and (or) circadian rhythm disorders. Nowthere are growing evidence indicate that ISF Aβ levels exhibit diurnal fluctuation, andsleep disorders will accelerate Aβ deposition, it was thought that this may be related tochanges in neuronal activity, oxidative stress and melatonin levels in sleep disorders,however, the specific mechanism is not clear.LINGO-1(LRR and Ig domain-containing, Nogo Receptor interacting protein1) isencoded by chromosome15(15q24.3, GI:15029689), and is central nervous systemtransmembrane specific, function as a negative regulator of neuronsurvival, axonalregeneration and myelination, thus palys a crucial role innervous system development,nervous system repairment, and is tightly related to Parkinson’s disease, idiopathic tremorand multiply sclerosis. Recently, it was reported that, LINGO-1also involved in theregulation of AD pathological process, and it can interact with APP, facilite the cleavage ofBACE1, However, its mechanism is not yet been elucidated, Lingo1may either promotethe activity or expression of the β-secretase enzyme, or inhibit the action of the enzymeα-secretase.However, the regulatory mechanism of LINGO-1is still not clear, the increased expre-ssion was seen in PD patients, PD animal model, model of central nervous system injuryand patients carrying lingo1rs9652490allele, neuron damage and death will lead to increa-sed expression of LINGO-1.Thus, Zhou et.al thought that LINGO-1expression maybeassociated with oxidative stress and gene mutations. Trifunovski confirmed the increasedneuronal activity can promote the expression of LINGO-1. sleep/wake state is closelyrelated to neuronal activity, and studies have shown that sleep deprivation can lead to thebody’s sustained activation of the default mode network function.The evidence above suggests that sleep/wake may affect the expression of LINGO-1by affectting neuronal activity. LINGO-1may play a mediated role in Abeta depositioninduced by sleep deprivation.This study consists of two parts. The first part is to idetify whether sleep/wakeregulate LINGO-1expression by means of Western blot and fragment sleep deprivationmodels, secondly, using RNA interference and co-immunoprecipitation method,we try to confirm whether LINGO-1play a mediated role Aβ deposition caused by sleep deprivation,and to explore its possible mechanism.The main results of this study are as follows:1. Fragment sleep can lead to upregulation of LINGO-1in different brain regions ina time-dependent way. After3days fragment sleep deprivation, ICR mice weresacrificed, Western blot was performed to test the expression of LINGO-1in frontal lobe,temporal lobe, hippocampus and hypothalamus. Compared with the control group, therewas a significant increase of expression of LINGO-1. Then ICR mice were given1、3、5、7day sleep deprivation, respectively and then detect the expression of LINGO-1,wefound that LINGO-1expression and the duration of fragments sleep deprivation werepositively correlated.2. The expression of LINGO-1displays circadian rhythm. Western blot wasperformed to test the experssion of LINGO-1at time point0:00、4:00、8:00、12:00、16:00、20：00. We found that LINGO-1expression at4am was significantly higher thanthat of other time points.3. Fragments sleep deprivation can lead to increased expression of BACE1. After3days fragment sleep deprivation, ICR mice were sacrificed. Western blot was perfo-rmed to test the expression of BACE1in the temporal lobe, we found that there was aincreased BACE1expression compared with control group.4. LINGO-1involved in the regulation of BACE1expression. Neurons were tran-sfected with lingo-1RNAi lentivirals, Western blot was performed to test the expres-sion of BACE1, we found that there was a down regulation of BACE1after endo-genous interference of lingo-1expression5. Immunoprecipitation shows LINGO-1and BACE1dose not interact with eachother in vivo.6. Fragment sleep deprivation can lead to the decreased phosphorylation of GSK3β.After three days of fragment sleep deprivation, temporal lobe was taken,p-GSK3β andtotal-GSK3β expression were detected by Western blot, compared with the controlgroup,GSK3β phosphorylation decreased.7. LINGO-1involved in the regulation of GSK3β phosphorylation. Neurons weretransfected with lingo-1RNAi lentivirals,,p-GSK3β and total-GSK3β expression weredetected by Western blot, compared with the control group, GSK3phosphorylationincreased. 8．Immunoprecipitation shows endogenous GSK3β interacts with LINGO一1inmouse brain tissue.In conclusion, we found that, LINGO-1expression is regulated by the sleep/wakestate; LINGO-1indirectly regulates BACE1expression by regulating GSK3βphosphorylation levels, which mediates APP processing regulated by sleep deprivation.