Transcriptome and translatome analyses reveal the regulatory role of betaine in high fat diet (HFD)-induced hepatic steatosis

Abstract Non-alcoholic fatty liver disease (NAFLD) is a common disease with a multitude of complications. Increasing evidence shows that the dietary supplement with betaine, a natural chemical molecule, can effectively reduce the fat accumulation in the liver. Translational regulation is considered to play a vital role in gene expression, but whether betaine functions through the regulation of gene translational level is still unclear. To this end, RNC-seq (ribosome-nascent chain complex bound mRNA sequencing) and RNA-seq co-analyses were performed to identify betaine target genes by using the liver samples from high-fat diet + betaine treated and high-fat diet treated mice. The results showed that betaine does play a lipid-lowering role by regulating the expression of gene translation levels; some NAFLD- and lipid metabolism- associated genes were differentially expressed at translational level, for example. And the mRNA translation ratio (TR) of gene significantly increased after betaine treatment. Besides, it is found that the regulation of some genes at transcriptional level is opposite to that at translational level, which indicates that transcriptional regulation and translational regulation may be independent from each other. Finally, we identified several candidate genes, especially Gpc1 , which may mediate the lipid-lowering effect of betaine in the liver. To sum up, this study depicted the molecular portrait of mice liver with or without betaine treatment from the angel of translatome and transcriptome, giving insights into the molecular mechanism of betaine-mediated lipid-lowering effect and also providing new clues for understanding and prevention of NAFLD.