Mitochondrial Unfolded-Protein Response Inhibit Aggregation Toxicity Of Amyloid-? Protein

As the world's population ages,neurodegenerative diseases are receiving much attention.However,there are currently no drugs that can completely cure these neurodegenerative diseases.Although there is a deeper understanding of the pathogenesis of Alzheimer's disease?AD?,its exact pathogenesis remains unclear.Many studies have shown that mitochondrial dysfunction is closely related to some neurodegenerative diseases in human body.The protein homeostasis of mitochondria is closely related to the pathological processes of AD and Parkinson's disease?PD?.Therefore,regulation of mitochondrial homeostasis is expected to be an effective strategy to interfere with the pathological process of such diseases.Mitochondrial unfolded protein response(UPR^mt)is a conserved stress response signaling pathway in mitochondria,which is an early protective response to mitochondria when functional damage occurs,and AD patients are accompanied by mitochondrial functional damage.Therefore,UPR^mt has the potential for neuroprotection.In this paper,a plant-specific nematode RNA interference bacterium capable of triggering UPR^mt was constructed.The model of Caenorhabditis elegans?C.elegans?expressing hsp-6::GFP was used to verify the effective effect of the constructed RNA interference bacteria on triggering UPR^mt.Then,the effect of UPRmt on behavioral dysfunction of AD nematode model was evaluated by using the transgenic nematode model of A?expression,and the content of A?protein in nematodes was quantitatively detected by thioflavin T staining.The effect of UPR^mt on the lifespan of the wild-type nematode model was evaluated using wild-type C.elegans.The COPAS platform was then used to quantitatively detect the size of the interfered and un interfered AD nematode models and evaluate their development.The ATP content and reactive oxygen species in the AD model nematodes affected by UPR^mt were detected.An transgenic C.elegans model was used to detect the activation of DAF-16 transcription factor after UPR^mt initiation and the activation of it's downstream genes sod-3.Finally,the inhibition mechanism of UPR^mt on A?protein toxicity was further studied by mRNA sequencing of AD nematode model.Experiments with the hsp-6::GFP-expressing C.elegans transgenic model SJ4100 showed that all those four RNA-interfering bacteria constructed could trigger UPR^mt and significantly reduce the mRNA levels of interfered gene?tomm-22,E04A4.5,cco-1 and uno-1?.Experiments using the C.elegans AD model CL4176 showed that activated UPR^mt can reduce the paralysis rate of CL4176 nematodes and reduce the A?protein content in the nematodes.At the same time,experiments using COPAS to detect the size of the interfered CL4176 nematodes showed that the anti-A?protein aggregation induced by mitochondrial gene silencing was not related to the developmental delay caused by mitochondrial gene silencing.Indicators showed that activated UPRmt reduced ATP content and reactive oxygen species in CL4176 nematodes,indicated that UPRmt may alleviate the toxicity of A?aggregation by alleviating oxidative stress.Experiments using wild type C.elegans N2 have shown that activation of UPR^mt can extend lifespan.Experiments using the daf-16::GFP-expressing C.elegans transgenic model GR1352 showed that UPR^mt can promote the entry of DAF-16 transcription factor into the nucleus.Meanwhile,experiments using the C.elegans transgenic model,expressing sod-3::GFP,CF1553,showed that UPR^mt can also promote the activation of sod-3.Further,mRNA sequencing results of AD model CL4176 showed that UPR^mt's delay of the process of AD may be associated to the related signaling pathways of autophagy and apoptosis.In summary,UPR^mt can not only alleviate the behavioral dysfunction of the AD model caused by A?accumulation,it can also reduce A?protein content in nematodes and prolong the lifespan of C.elegans.These results provide a preliminary basis for further understanding and expansion of UPR^mt's therapeutic mechanisms for neurodegenerative diseases.The use of drugs or treatments that target mitochondrial unfolded protein response may be an effective treatment for diseases such as neurodegenerative diseases.