Inhibition Of MiR-149 On Histone Deacetylase 1 Is Implicated In The Regulation Of Fructo-oligosaccharides In Insulin Degrading Enzyme Expression Of AD Model Mice Brain

Objective: Alzheimer’s disease(AD)is a disease occurs in aged and presenile,and is the most important type of dementia.The insidious onset of AD is mainly manifested in a certain degree of mental symptoms and behavioral disorders.As the disease get worse,the patients’ cognitive function decline and gradually lose the ability to take care of themselves.The theory of amyloid beta is generally accepted about the development of AD,that is,abnormal accumulation of β-amyloid protein(Aβ)in brain caused by imbalance of production and clearance of amyloid beta in brain leads to AD.The main pathological features of AD occur earlier than cognitive impairment,and the accumulation of Aβ is considered to be an important pathological feature of AD.Therefore,early intervention through brain Aβ clearance has become an important method of prevention and treatment of AD.Insulin degrading enzyme(IDE)is one of the major Aβ-degrading enzymes.Studies have confirmed that overexpression of IDE can delay the occurrence of Aβ-related pathological features,while the level of Aβ in the brain of IDE deficient mice increased significantly,and cognitive impairment was improved.Histone acetylation plays an important role in AD.Histone deacetylases(HDACs)inhibitors are molecular targets for the prevention and treatment of AD.HDAC1 can up-regulate the ability of learning and memory.Inhibition of HDAC1 can improve the cognitive impairment of AD.Studies have shown that HDAC1 can participate in the regulation of IDE gene expression by binding to the promoter of IDE,indicating that HDAC1 can up-regulate the expression of IDE in AD brain.Prebiotics is a kind of natural dietary supplements that can promote health by improving the intestinal microflora.Their role in neuroprotection has attracted much attention.Fructo-oligosaccharide(FOS)has been proved to alleviate the deposition of Aβ in AD mice brain and reduce the damage of nerve function.FOS inhibits HDAC1,but whether FOS can inhibit IDE through HDAC1 is still unclear.Micro RNA(miRNA)is a kind of highly conserved non-coding RNA,which is involved in the occurrence and differentiation of neurons.Studies showed that the expression of miR-149 decreased in gray matter.Bioinformatics predicts that miR-149 can inhibit the expression of HDAC1,these finding suggest that the increase expression of HDAC1 in AD brain may be related to the low expression of miR-149.However,whether miR-149 mediates the regulation of HDAC1 expression in AD brain by FOS remains unclear.In conclusion,this study explores the inhibition of miR-149 on HDAC1 and its effect in fructooligosaccharide regulating IDE expression in the brain of AD model mice in vitro and in vivo.The results of our research can provide the prevention and treatment of AD a theoretical basis for explaining the pathogenesis and exploring.Methods:Five-month-old AD model mice and wild type mice were divided into four groups: AD model group,intervention group,wild control group and wild intervention group.Feed the mice in intervention group with water containing 5%FOS,while feed the mice in AD and control group with pure water.After 6 months,the neuroethology of mice was detected by avoiding darkness test.Used Sulfur T staining method to detect the accumulation of Aβ in mice brain.The expression level of miR-149 in brain tissue were measured by q RT-PCR,and the expression level of IDE and HDAC1 in brain tissue were measured by q RT-PCR and Western Blotting.In addition,miR-149 mimics and inhibitors were used to treat SH-SY5 Y cellsin vitro.Then the expression levels of HDAC1 and IDE gene and protein were determined by q RT-PCR and Western Blotting.SiRNA interference technology was used to silence HDAC1 gene in SH-SY5 Y cells,and then q RT-PCR and Western Blotting were used to determine the IDE expression level of cells.Results: 1.No abnormal performance and death in mice was found during the experiment,and there was no significant difference in food and water intake of mice in each group.The weight of mice in each group increased,and there was no significant difference in each group.2.As the avoiding darkness test showed,the latent period in AD model group was decreased and the number of errors was increased compared with those in the wild control group(P<0.01).The latent period in AD intervention group was increased and the number of errors was decreased compared with those in the AD model group(P<0.01).3.The number of Aβ plaques in AD brain tissue was higher than that in brain tissue of wild control group(P<0.01);The number of Aβ plaques in brain was decreased in AD intervention group compared with that in AD model group(P< 0.01).4.The increased expression of IDE was found in the brain tissue of AD mice compared with that in mice of control group(P<0.01);The decreased expression of IDE was found in the brain tissue of mice in AD intervention group compared with that in mice of AD model group(P<0.01).5.The increased expression of HDAC1 was found in the brain tissue of AD mice compared with that in mice of control group(P<0.01);The decreased expression of HDAC1 was found in the brain tissue of mice in AD intervention group compared with that in mice of AD model group(P<0.01).6.Compared with control group,the expression of miR-149 in mice brain tissue was decreased in both AD model group and AD intervention group(P<0.01),while the increased expression of miR-149 was found in the brain tissue of mice in AD intervention group compared with that in mice of AD model group(P<0.01).7.In miR-149 mimics group,the expressions of HDAC1 m RNA and protein were decreased,the expression of IDE m RNA was increased but the protein was decreased.In miR-149 inhibitors group,the expressions of HDAC1 m RNA and protein were increased,the expression of IDE m RNA was decreased but the protein was increased.8.The relative expression of IDE in HDAC1-silenced SH-SY5 Y cells was increased(P<0.01).Conclusion: FOS could alleviate the abnormal accumulation of Aβ in the brain of AD model mice and improve their cognitive impairment.Inhibition of miR-149 on HDAC1 may participate in the regulation of FOS on IDE in AD model mice brain.