Dietary betaine activates hepatic VTGⅡexpression in laying hens associated with hypomethylation of GR gene promoter and enhanced GR expression  

作　　者：Nagmeldin A.Omer Yun Hu Yan Hu Abdulrahman A.Idriss Halima Abobaker Zhen Hou Haibo Dong Ruqian Zhao 

机构地区：[1]MOE Joint International Research Laboratory of Animal Health&Food Safety,Nanjing Agricultural University,Nanjing 210095,People’s Republic of China [2]Key Laboratory of Animal Physiology&Biochemistry,Nanjing Agricultural University,Nanjing 210095,People’s Republic of China [3]Jiangsu Collaborative Innovation Centre of Meat Production and Processing,Quality and Safety Control,Nanjing 210095,People’s Republic of China [4]Poultry Institute,Chinese Academy of Agriculture Sciences,Yangzhou,Jiangsu,China

出　　处：《Journal of Animal Science and Biotechnology》2018年第2期381-390,共10页畜牧与生物技术杂志（英文版）

基　　金：supported by the National Natural Science Foundation of China(31672512);Special Fund for Agro-scientific Research in the Public Interest(201003011);the Fundamental Research Funds for the Central Universities(KYZ201212);the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)

摘　　要：Background: Vitellogenin(VTG) is a precursor of egg yolk proteins synthesized within the liver of oviparous vertebrates. Betaine is an important methyl donor that is reported to improve egg production of laying hens with an unclear mechanism. In the present study, we fed betaine-supplemented diet(0.5%) to laying hens for 4 wk and investigated its effect on VTGII expression in the liver.Results: Betaine did not affect chicken weight, but significantly(P < 0.05) increased egg laying rate accompanied with a significant(P < 0.05) increase in hepatic concentration and plasma level of VTGI. Plasma estrogen level did not change,but the hepatic expression of estrogen receptor α(ERα) mR NA was significantly(P < 0.05) up-regulated. Betaine did not affect the protein content of ERα, but significantly(P < 0.05) increased hepatic expression of glucocorticoid receptor(GR)at both mR NA and protein levels. Also, ERα/GR interaction tended to be enhanced in the liver nuclear lysates of betainesupplemented hens as determined by co-immunoprecipitation. Furthermore, dietary betaine supplementation significantly increased(P < 0.05) the hepatic expression of methyl-transfer enzymes, such as BHMT, GNMT, and DNMT1,which was associated with higher SAM/SAH ratio and hypomethylation of GR promoter regions.Conclusions: Betaine activates hepatic VTGII expression in association with modified DNA methylation of GR gene promoter, GR expression and ERα/GR interaction. Activation of hepatic VTGII expression may contribute, at least partly, to improved egg production in betaine-supplemented hens.Background: Vitellogenin(VTG) is a precursor of egg yolk proteins synthesized within the liver of oviparous vertebrates. Betaine is an important methyl donor that is reported to improve egg production of laying hens with an unclear mechanism. In the present study, we fed betaine-supplemented diet(0.5%) to laying hens for 4 wk and investigated its effect on VTGII expression in the liver.Results: Betaine did not affect chicken weight, but significantly(P < 0.05) increased egg laying rate accompanied with a significant(P < 0.05) increase in hepatic concentration and plasma level of VTGI. Plasma estrogen level did not change,but the hepatic expression of estrogen receptor α(ERα) mR NA was significantly(P < 0.05) up-regulated. Betaine did not affect the protein content of ERα, but significantly(P < 0.05) increased hepatic expression of glucocorticoid receptor(GR)at both mR NA and protein levels. Also, ERα/GR interaction tended to be enhanced in the liver nuclear lysates of betainesupplemented hens as determined by co-immunoprecipitation. Furthermore, dietary betaine supplementation significantly increased(P < 0.05) the hepatic expression of methyl-transfer enzymes, such as BHMT, GNMT, and DNMT1,which was associated with higher SAM/SAH ratio and hypomethylation of GR promoter regions.Conclusions: Betaine activates hepatic VTGII expression in association with modified DNA methylation of GR gene promoter, GR expression and ERα/GR interaction. Activation of hepatic VTGII expression may contribute, at least partly, to improved egg production in betaine-supplemented hens.

关 键 词：BETAINE Glucocorticoid receptor HYPOMETHYLATION Laying HENS VITELLOGENIN 

分 类 号：S[农业科学]