Prenatal betaine exposure modulates hypothalamic expression of cholesterol metabolic genes in cockerels through modifications of DNA methylation

Abstract

Cholesterol is essential for neuronal development and brain function. Previously we reported that in ovo administration of betaine modulates hepatic cholesterol metabolism in the chicken, yet it remains unknown whether maternal betaine affects the cholesterol content and the expression of cholesterol metabolic genes in chicken hypothalamus. In this study, eggs were injected with saline or betaine at 2.5 mg/egg, and the hatchlings were raised under the same condition until 64 d of age. Maternal betaine significantly (P = 0.05) increased the body weight and suppressed aggressive behavior of 64-day-old cockerels, in association with significantly (P < 0.05) up-regulated expression of 5-HTR1A receptor in the hypothalamus. Concurrently, betaine in ovo significantly increased (P < 0.05) the hypothalamic content of total cholesterol and cholesterol ester, which coincided with significantly up-regulated (P < 0.05) hypothalamic expression of cholesterol biosynthetic genes, such as sterol-regulatory element binding protein 2 and 3-hydroxy-3-methyl-glutaryl-CoA reductase as well as acetyl-CoA cholesterol acyltransferase 1, which converts free cholesterol to cholesterol ester for storage. In contrast, low density lipoprotein receptor, which mediates the cholesterol uptake, was significantly down-regulated (P < 0.05). In ovo betaine administration significantly enhanced the expression of betaine-homocysteine methyltransferase and DNA methyltransferase 1 (P < 0.05), which was associated with alterations of CpG methylation on the promoter of modified cholesterol metabolic genes. These results indicate that maternal betaine modulates hypothalamic cholesterol metabolism in cockerels through modifying DNA methylation on the promoter of cholesterol metabolic genes.

Maternal betaine supplementation decreases hepatic cholesterol deposition in chicken offspring with epigenetic modulation of SREBP2 and CYP7A1 genes

“…We previously reported that supplementation of betaine could affect cholesterol metabolism in offspring by affecting carbon metabolism and DNA methylation ( Hu et al., 2015 , Idriss et al., 2017 , Zhao et al., 2019 ). In this study, maternal betaine supplementation significantly enhanced methionine metabolism and methyl transfer genes expression of BHMT, AHCYL, and DNMT1 at protein levels in the offspring chicken liver, which agrees with a previous finding that maternal betaine supplementation causes BHMT and DNMT1 upregulation in the hypothalamus of offspring cockerels ( Idriss et al., 2017 ). It is worth noting that, one carbon metabolism is essential for providing methyl group to the methylation of DNA, RNA, and histone methylation, thus playing a critical role in the epigenetic gene regulation.…”

“…Cholesterol and its metabolites are implicated in the pathogenesis of various human diseases, including atherosclerosis, cancer, neurodegenerative diseases, and non-alcoholic fatty liver disease ( Wu et al., 2013 , Coisne et al., 2016 , Van den Berg et al., 2018 , Ou et al., 2019 ). In the chicken, cholesterol metabolism in the brain and muscle was associated with aggressive behavior and meat quality, respectively ( Attia et al., 2017 , Idriss et al., 2017 ). Importantly, cholesterol level in the liver is an indicator of chicken fatty liver syndrome.…”

Fetal betaine exposure modulates hypothalamic expression of cholesterol metabolic genes in offspring cockerels with modification of promoter DNA methylation

“…Total RNA, genomic DNA, and total protein were isolated from ground chicken hypothalamic samples, and Methylated DNA Immune Precipitation ( MeDIP ) assay was hired to observe the CpG methylation status on the promoter sequences of corresponding genes. Detailed protocols are the same as those described in our previous article ( Idriss et al., 2017 ). To be clear, all of the primers used for quantitative real-time PCR are listed in the first part of Table 1 , and the primers used for MeDIP assay are marked with “- promoter” tails.…”

“…Also, feeding methyl-enriched diet exclusively to F0 boars significantly changed the carcass traits, gene expression and DNA methylation in F2 generation ( Braunschweig et al., 2012 ). Recently, we reported that in ovo administration of betaine modulated hypothalamic expression of cholesterol metabolism genes in chicken ( Idriss et al., 2017 ). However, it remains unknown whether this effect will continue to be transmitted to subsequent generations of chickens.…”

Interaction between early-life pet exposure and methylation pattern of ADAM33 on allergic rhinitis among children aged 3–6 years in China

“…DNA methylation level was analyzed by a multiplex PCR and next-generation sequencing-based targeted CpG methylation analysis method-MethylTarget ™ (Genesky Biotechnologies Inc., Shanghai, China). The validity and reliability of this method have been previously reported [22][23][24]. Specifically, CpG islands located in the promoter of genes of interest were selected according to the following criteria: (1) 200 bp minimum length; (2) above 50% GC-content; (3) above 0.6 ratio of observed/ expected CpG.…”