| Poptosis is the programmed cell death regulated by gene,and the disorder of apoptosis process is directly or indirectly related to the occurrence of many diseases.Such as tumors,autoimmune diseases,neurodegenerative diseases,etc.,have important biological significance and complex molecular biological mechanisms.It involves the activation,expression and regulation of a series of genes.Alzheimer’s disease(AD),A neurodegenerative disease,is characterized by cerebral cortex atrophy accompanied by deposition of beta amyloid protein(A),neurofibrillary tangles,and degeneration and apoptosis of memory neurons.Studies have shown that the non-reproducibility of neurons makes the brain function decline caused by neuronal apoptosis an irreversible process.One of the important directions of current treatment is how to block the degeneration and apoptosis of a large number of neurons.However,the mechanism of neuronal apoptosis is still unclear.Presenilin 1(PS1)is a risk gene for Alzheimer’s disease.Mutations in PS1 can be detected in 50% of familial Alzheimer’s disease,and overexpression of PS1 can be detected in many AD patients.PS1 has the properties of-secretase and can be involved in shearing APP to produce Aβ.The aggregation of Aβ is also closely related to neuronal apoptosis.Presenilin1-Associated Protein(PSAP)is a mitochondria-specific pro-apoptotic protein that is also highly expressed in patients with Alzheimer’s disease and can interact with PS1.We have demonstrated that PS1 induces apoptosis through both its gamma-secretase activity and the PSAP mitochondrial pathway.DR6 is a member of the death receptor family.Overexpression of DR6 in cells induces apoptosis.A 2009 paper in Nature showed that DR6 can combine with N-APP,the precursor of Aβ,to cause the deformation and degeneration of neurons.In addition,another paper demonstrated that DR6 was associated with apoptosis of tumor cells.A large number of literatures and our previous experiments have shown that DR6 is closely related to apoptosis.This paper mainly discusses the role and interrelationship of PS1,PSAP and DR6 in the apoptosis associated with Alzheimer’s disease.In cells treated with TNFα in combination with CHX,DR6 was shown to interact with PSAP,which was discovered by interacting with PS1,which plays an important role in PS1-induced apoptosis.Therefore,in order to clarify the role of PSAP in DR6-induced apoptosis,we used siRNA technology to reduce the protein expression level of PSAP,and the results showed that the production of DR6-induced PARP protein cleavage and the activation of caspases were almost completely inhibited,proving that PSAP plays a important role in DR6-induced apoptosis.The formation of PSAP-DR6 and PSAP-Bax complex was detected by immunoprecipitation technology.In this paper,only DR6-Bax complex was detected in cytoplasmic components,while Bax-PSAP complex was detected in mitochondrial components,and it was found that PSAP could regulate the transfer of Bax from cytoplasm to mitochondria.Although PSAP can block DR6-induced PARP cleavage and caspase activation,they cannot affect the formation of DR6-induced related complexes.Although both PSAP and Bax can block DR6-induced PARP cleavage and caspase activation,they cannot affect the formation of DR6-induced related complexes.In order to further explore the relevant molecular mechanism,we further studied the role of PS1 in DR6-induced apoptosis.In this paper,the interaction between DR6 and PS1 and the interaction between PS1 and Bax were detected in dr6-induced apoptosis through immunoprecipitation technology.When the protein expression of PS1 was decreased,DR6-induced apoptosis was completely inhibited.Unlike PSAP,the deletion of PS1 blocked the formation of DR6-induced PSAP-DR6,PSAP-Bax and Bax-DR6 complex,which proved that PS1 played a crucial role in DR6-induced apoptosis.In order to further clarify the molecular mechanism of the interaction between DR6 and PS1 and PSAP,mitochondria and mitochondria-associated ER membranes(MAM)were isolated by sucrose concentration gradient centrifugation method,and DR6 and PS1 were found to be expressed in mitochondria and MAM.This indicates that as a transmembrane protein,the interaction between DR6 and mitochondrial related protein PSAP may occur on MAM,and the interaction between DR6 and PS1 may also occur on MAM,providing strong evidence for the search for the binding location of the interaction between DR6,PSAP and PS1,which is the basis of their interaction.In this paper,our research is helpful to further clarify the pathogenic mechanism of Alzheimer’s disease.It could help develop new drugs to prevent or delay Alzheimer’s disease. |
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