Effects of Mitochondrial Unfolded-Protein Response on Aggregation Toxicity of Amyloid-β Protein / 中山大学学报(医学科学版)

ABSTRACT

[Objective] To investigate the effects of mitochondrial unfolded-protein response (UPRmt) on the aggregation toxicity of Aβ protein in Alzheimer's disease (AD).[Methods] By cloning the mitochondrial outer membrane tomm-22,inner membrane E04A4.5 and atfs-1 genes of Caenorhabditis elegans (C.elegans) and constructing the L4440 interference vectors,HT115 competent cells were transformed to prepare tomm-22,E04A4.5 and atfs-1 RNAi bacteria.The effects of tomm-22 and E04A4.5 RNAi on the process of paralysis were investigated through transgenic AD disease models CL4176 and CL2006.The life span of wild type N2 C.elegans was observed after RNAi of tomm-22 and E04A4.5.The regulatory role of ATFS-1 signaling by atfs-1 RNAi in inhibition of Aβ protein aggregation was detected.The dynamic changes of UPRmt in transgenic SJ4100 nematode and the autophagy level in transgenic DA2123 nematodes were analyzed by tomm-22 and E04A4.5 RNAi.[Results] We successfully established the UPRmt model by cloning mitochondrial tomm-22 and E04A4.5 of C.elegans and further constructing RNAi bacteria,and showed that they can suppress aggregation toxicity of Amyloid-β (Aβ) protein in AD model CL4176,and slow down paralysis process.The life span of wild type N2 was significantly shortened after feeding with the tomm-22 and E04A4.5 RNAi bacteria.At the same time,the progressive paralysis AD model CL2006 shows a delayed paralysis in the early stage of life cycle but get acceleration in the late.These results illustrate that the UPRmt can alleviate the mitochondrial stress and improve the function of mitochondria at least in the short term.The atfs-1 RNAi confirmed that delayed paralysis process of AD model CL4176 is not directly related to the ATFS-1 signal.However,tomm-22 and E04A4.5 RNAi can gradually increase the UPRmt response and induce the expression level of autophagy-related molecules LGG-1,suggesting that tomm-22 and E04A4.5 RNAi may play a role in delaying the AD disease process by enhancing the activity of autophagy in C.elegans.[Conclusions] The study found that the UPRmt can inhibit the accumulation of A β protein by coordinating the signal transduction between mitochondria and nucleus,and can help to restore mitochondria and even intracellular protein homeostasis for protecting the normal physiological function of cells,and also provides new targets for prevention and treatment of neurodegenerative diseases such as AD.