Altered C>U RNA Editing In Dyslipidemia And The Effect Of Apobec1 Depletion On It

Objective: Dyslipidemia,including abnormal levels of various lipids,is a key risk factor for many important metabolic diseases,such as coronary heart disease,atherosclerosis and nonalcoholic fatty liver disease(NAFLD).RNA editing from cytidine to uridine(C>U)is an important epigenetic process related to lipid metabolism.Apolipoprotein B m RNA editing enzyme(APOBEC),which mediates the editing of this RNA,is a class of evolutionarily conserved cytidine deaminases.Among them,Apolipoprotein B m RNA editing enzyme catalytic subunit 1(Apobec1)is a key gene in lipid metabolism,which can mediate the RNA editing of Apolipoprotein B(Apob)gene C>U in the intestine to produce truncated apo B48 protein,regulating lipid transport and metabolism.The depletion of Apobec1 can lead to abnormal regulation of apo B protein and cause dyslipidemia.However,it is currently unclear about other C>U RNA editing related to dyslipidemia.Therefore,this study analyzed the clinical samples of NAFLD patients and the high-fat diet(HFD)mouse model,as well as the C>U RNA editing of Apobec1 knockout(KO)mice,combined with the dyslipidemia of cynomolgus monkeys and cell models,to explore the changes in C>U RNA editing in dyslipidemia and its potential regulatory mechanisms and functional effects.Methods:(1)RNA editing analysis was performed on liver tissue RNA-Seq data from two NAFLD populations and four HFD mice in the NCBI Gene Expression Omnibus(GEO)database to analyze common changes in APOBEC editing enzymes and C>U editing sites.(2)By feeding wild-type(WT)mice and Apobec1 KO mice with HFD for 8 weeks,changes in Apobec1 editing enzyme and C>U editing events were analyzed using RNA-Seq,and key differential editing sites were screened and validated through Sanger sequencing.(3)The content of fatty acids related to hyperlipidemia(HLP)in the plasma of cynomolgus monkeys and mouse models was detected and analyzed using a gas chromatography-mass spectrometry(GC-MS)system.For this portion of fatty acids,taking palmitic acid(PA)as an example,we analyzed the publicly available RNA Seq data of different cell lines induced by PA in the GEO database to investigate the differences in C>U RNA editing caused by PA.Results:(1)Analysis of liver tissue RNA-Seq data from patients and mouse models showed that dyslipidemia may lead to increased expression of C>U editing enzymes APOBEC3 A and APOBEC3 B in patients,as well as the main C>U editing enzyme Apobec1 in mice,accompanied by more C>U RNA editing changes.A consistent significant difference was found in the data of two or more groups of mice.And in multiple sets of data,the RNA editing levels of Abcd3 and Cyp3a11 were significantly correlated with their expression levels,indicating the presence of cis expression regulation.(2)Compared with normal diet(NCD),HFD mice showed a significant increase in body weight(P < 0.05),with Apobec1 KO mice showing a more significant increase(P < 0.05).Compared with NCD,the plasma total cholesterol(TC)levels in HFD mice were relatively higher(P < 0.05).Compared with WT mice,Apobec1 KO mice showed a significant increase in plasma triglyceride(TG)(P < 0.05).The C>U RNA editing events in the transcriptome of peripheral blood leukocytes of Apobec1 KO mice with HFD were significantly reduced.RNA-Seq data analysis revealed and Sanger sequencing confirmed that HFD increased the C>U editing at Emp1: chr6: 135382527 locus,while the editing event tended to disappear after Apobec1 knockout.(3)GC-MS detection found that the plasma levels of PA in HLP cynomolgus monkeys and mice were significantly increased,while the plasma levels of PA in Apobec1 KO mice were significantly reduced.The relevant data of different cell lines also demonstrate that PA induced cells exhibit significant C>U editing changes.Conclusion: This study started from RNA-Seq data mining in the liver of HFD mice and NAFLD patients,combined with changes in C>U editing enzymes and editing sites in vivo,indicating that dyslipidemia cause a significant increase in RNA editing events in the body.Combining with the Apobec1 KO mouse model induced by HFD,the main regulatory gene for C>U editing changes in dyslipidemia was proposed and validated as Apobec1.And through the significant increase in plasma PA levels in high-fat animal models(mice and cynomolgus monkeys)and the absence of Apobec1 in mice,the plasma PA content was significantly reduced,indicating the important role of Apobec1 in the metabolism of fatty acids such as PA.At the same time,PA can induce significant changes in C>U RNA editing in different cell lines,indicating that PA is an important influencing factor in the increase of C>U editing events in dyslipidemia.This study revealed the changes in C>U RNA editing caused by dyslipidemia based on different HFD animal models and NAFLD patients.At the same time,Apobec1 KO mice and their plasma metabolomics were used to explore the dual effects of Apobec1 on C>U RNA editing,including direct catalytic effects and indirect effects produced by regulating lipid metabolism.