Mechanism Of BC1 And DAPK1 Mediating Learning Memory Impairment

Background Alzheimer's disease?AD?is a progressive neurodegenerative disorder,which is the major form of dementia.The major pathological hallmarks of AD are the extracellular amyloid plaques,intracellular neurofibrillary tangles?NFTs?,neuron loss and brain atrophy.As the disease progresses it can lead to cognitive impairment and eventually dementia.Amyloid-b?Ab?peptides and Tau protein are the mainly component of amyloid plaques and NFTs.For decades,therefore we were focus on Aband tau to treat AD,but recently we have no advance about the therapy.So,we need finding an optional treatment.Long noncoding RNA,lncRNA,that is,RNA longer than 200 nucleotides.LncRNA is mainly involved in X chromosome silencing,genomic imprinting,chromatin modification,transcriptional interference,nuclear transport and other important regulatory processes.Our group previously found that BC1 is a long non-coding RNA,which is widely expressed in the mouse brain.However,it is not clear how the content of BC1 changes in the brain of AD model mice,whether it affects the learning memory ability of mice,and whether it affects the Aband tau protein.Objective To classify the correlation between BC1 level and learning memory ability in AD and how BC1 regulates the amyloid precursor protein?APP?.The interaction between BC1 and APP was blocked by the synthesis of small molecule polypeptide to explore the treatment strategy of AD,providing theoretical basis and experimental data for the development of new AD treatment therapies.Methods We have been built in the pyramidal neurons?PN?specifically expression of green fluorescent protein?GFP?in mice,named PN^GFP+/+mice.AD/PN^GFP+/+mice were obtained by hybridizing the mice with AD model mice?Tg2576?. Illumination high-throughput sequencing was used to investigate the gene expression patterns in the individual PN^GFP+/+cells from two pairs of AD/PN^GFP+/+mice at 6 months old of age and the age-matched controls.qPCR and Western blots ?WB?were used to detect the mRNA and protein levels.The binding sequence of BC1and FMRP was identified by Electrophoretic mobility shift assay.The spatial learning memory were detected by Morris Water Maze?MWM?.The synaptic function was measured by electrophysiological recordings.Results The expression of BC1 is increased in the brain of AD mice,which shows the Abplaques similar to those observed in AD patients.BC1 induces APP mRNA translation via association with a fragile X syndrome protein?FMRP?.Inhibition of BC1 or BC1-FMRP association in AD mice blocks aggregation of Aband protects against the spatial learning memory deficits.Genetic manipulation of the non-transgenic control mice with the expression of exogenous BC1 in excitatory pyramidal neurons (PN^eBC1+/+mice)generates the phenotypes including Abpeptides accumulation and the spatial learning and memory impairments,consistent with those seen in AD mice.Conclusions Our results demonstrate the important role of BC1 in the regulation of APP translation in the pathological events of AD.This study provides a novel mechanism underlying aggregation of Abpeptides via BC1 induction of APP mRNA translation and hence warrants a promising target for AD therapy.Background Since the beginning of the 21 st century,Diabetes mellitus?DM?has become increasingly serious.Diabetes mellitus is a group of metabolic disorders caused by the interaction of genetic and environmental factors.DM is also a risk factor for most human diseases,such as cardiovascular disease and cognitive impairment.Globally,about 200,000 people die every day,of which one in seven deaths is related to DM.DM not only increases the incidence of disease,but also brings heavy burden to the society and family.However,there are no effective measures to alleviate the cognitive impairment of DM. Dendrites are one or more projections from the cell body and radiate out.The main function of dendrites is to receive stimuli and transmit impulses into the cell body.Unlike dendrites,each neuron has only one axon,the longest of which can be up to 1 meter long.The axon's main function is to transmit action potential to the synapse,while in the central nervous system,the axon's main function is to transmit nerve signals.A synapse is a structure in which the impulses of a neuron pass to another neuron or cell.Previous studies of our research group showed that netrin1 is an axon-oriented protein,whose main functions are axon guidance,neuron migration and morphogenesis of different branch structures.So how does netrin1 change in DM? A treatment for netrin1 would help alleviate the DM cognitive impairment?Objective To classify the changes of netrin1 in DM,and the role and mechanism of netrin1 in learning memory.Methods The contents of netrin1 in the mouse brain were detected by Western Blot?WB?and immunofluorescence?IF?at 6 months old of DM model mice.Netrin1 overexpressed virus or inhibitory virus was designed and injected into the hippocampus of adult mice by stereotactic injection.The effects of netrin1 on learning memory were tested by Morris Water Maze and other experiments.Our lab had built DAPK1 DD loxp mice,named DDloxp/loxp,and then breeding with DM model mice,we can obtain DM/DDloxp/loxp,and when breeding with Ca MK?-? cre mice,induced by tamoxifen?TAMF?,we can obtain the excitatory neurons DAPK1 DD knockout mice,named DM/DD-/-.Using the WB,IF and MWM to test the influence of DAPK1DD-/-in DM mice and the relationship between netrin1 and DAPK1.Results 1.In the brain of DM mice,the level of netrin1 drops sharply;2.Injection the netrin1 overexpressed virus into the brain of DM mice will improve the learning memory ability,while injection the netrin1 inhibitory virus into the brain of C57BL/6J will impaire the learning memory ability;3.After the DD was knocked out,the normal development and motor ability of DM mice were not affected,but the learning memory ability of the DM mice was improved;After the DD was knocked out,the level of netrin1 in the DM mice was increased.4.In order to further verify the relationship between netrin1 and DAPK1,we injected netrin1 inhibitory virus into the brains of DM/DD-/-mice and overexpressed netrin1 virus into the brains of DM/DDloxp/loxp mice at the age of 5 months old,then at the age of 6 months old,we will test the mice.The results showed that DM/DD-/-mice had the same memory impairment as ordinary DM mice,while the memory ability of DM/DDloxp/loxp mice was improved.Discussion DAPK1 affects the learning memory ability of DM mice by regulating netrin1,and the decrease of netrin1 may be the key pathophysiological factor of cognitive impairment in DM.