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

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.

Maternal betaine suppresses adrenal expression of cholesterol trafficking genes and decreases plasma corticosterone concentration in offspring pullets

Background:Laying hens supplemented with betaine demonstrate activated adrenal steroidogenesis and deposit higher corticosterone(CORT)in the egg yolk.Here we further investigate the effect of maternal betaine on the plasma CORT concentration and adrenal expression of steroidogenic genes in offspring pullets.Results:Maternal betaine significantly reduced(P<0.05)plasma CORT concentration and the adrenal expression of vimentin that is involved in trafficking cholesterol to the mitochondria for utilization in offspring pullets.Concurrently,voltage-dependent anion channel 1 and steroidogenic acute regulatory protein,the two mitochondrial proteins involved in cholesterol influx,were both down-regulated at m RNA and protein levels.However,enzymes responsible for steroid syntheses,such as cytochrome P450 family 11 subfamily A member 1 and cytochrome P450 family 21 subfamily A member 2,were significantly(P<0.05)up-regulated at m RNA or protein levels in the adrenal gland of pullets derived from betaine-supplemented hens.Furthermore,expression of transcription factors,such as steroidogenic factor-1,sterol regulatory element-binding protein 1 and c AMP response element-binding protein,was significantly(P<0.05)enhanced,together with their downstream target genes,such as 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase,LDL receptor and sterol regulatory element-binding protein cleavage-activating protein.The promoter regions of most steroidogenic genes were significantly(P<0.05)hypomethylated,although methyl transfer enzymes,such as AHCYL,GNMT1 and BHMT were up-regulated.Conclusions:These results indicate that the reduced plasma CORT in betaine-supplemented offspring pullets is linked to suppressed cholesterol trafficking into the mitochondria,despite the activation of cholesterol and corticosteroid synthetic genes associated with promoter hypomethylation.

Negative effects of long-term feeding of high-grain diets to lactating goats on milk fat production and composition by regulating gene expression and DNA methylation in the mammary gland

Background： It is well known that feeding a high concentrate（HC） diet to lactating ruminants likely induces subacute ruminal acidosis（SARA） and leads to a decrease in milk fat production. However, the effects of feeding a HC diet for long periods on milk fatty acids composition and the mechanism behind the decline of milk fat still remains poorly understood. The aim of this study was to investigate the impact of feeding a HC diet to lactating dairy goats on milk fat yield and fatty acids composition with an emphasis on the mechanisms underlying the milk fat depression. Seventeen mid-lactating dairy goats were randomly allocated to three groups. The control treatment was fed a low-concentrate diet（35% concentrate, n = 5, LC） and there were two high-concentrate treatments（65% concentrate, HC）, one fed a high concentrate diet for a long period（19 wks, n = 7, HL）; one fed a high concentrate diet for a short period of time（4 wk, n = 5, HS）. Milk fat production and fatty acids profiles were measured. In order to investigate the mechanisms underlying the changes in milk fat production and composition,the gene expression involved in lipid metabolism and DNA methylation in the mammary gland were also analyzed.Results： Milk production was increased by feeding the HC diet in the HS and HL groups compared with the LC diet（P 〈 0.01）, while the percentage of milk fat was lower in the HL（P 〈 0.05） but not in the HS group. The total amount of saturated fatty acids（SFA） in the milk was not changed by feeding the HC diet, whereas the levels of unsaturated fatty acids（UFA） and monounsaturated fatty acids（MUFA） were markedly decreased in the HL group compared with the LC group（P 〈 0.05）. Among these fatty acids, the concentrations of C15：0（P 〈 0.01）, C17：0（P 〈 0.01）, C17：1（P 〈 0.01）, C18：1 n-9 c（P 〈 0.05）, C18：3 n-3 r（P 〈 0.01） and C20：0（P 〈 0.01） were markedly lower in the HL group, and the concentrations of C20：0（P 〈 0.05） and C18：3 n-3 r（P 〈 0.01） were lower in the HS group compared with the LC group. However, the concentrations of C18：2 n-6 c（P 〈 0.05） and C20：4 n-6（P 〈 0.05） in the milk fat were higher in the HS group. Real-time PCR results showed that the m RNA expression of the genes involved in milk fat production in the mammary gland was generally decreased in the HL and HS groups compared with the LC group. Among these genes, ACSL1, ACSS1 ＆ 2, ACACA, FAS, SCD, FADS2, and SREBP1 were downregulated in the mammary gland of the HL group（P 〈 0.05）, and the expressions of ACSS2, ACACA, and FADS2 m RNA were markedly decreased in the HS goats compared with the LC group（P 〈 0.05）. In contrast to the gene expression, the level of DNA methylation in the promoter regions of the ACACA and SCD genes was increased in the HL group compared with the LC group（P 〈 0.05）. The levels of ACSL1 protein expression and FAS enzyme activity were also decreased in the mammary gland of the HL compared with the LC group（P 〈 0.05）.Conclusions： Long-term feeding of a HC diet to lactating goats induced milk fat depression and FAs profile shift with lower MUFAs but higher SFAs. A general down-regulation of the gene expression involved in the milk fat production and a higher DNA methylation in the mammary gland may contribute to the decrease in milk fat production in goats fed a HC diet for long time periods.

In ovo leptin administration affects hepatic lipid metabolism and microRNA expression in newly hatched broiler chickens

Background： A leptin-like immunoreactive substance has been found in chicken eggs and has been implicated in serving as a maternal signal to program offspring growth and metabolism. In the present study, we investigated the effects of in ovo leptin administration on hatch weight, serum and hepatic concentrations of metabolites and hormones, as well as on the expression of genes involved in hepatic lipid metabolism and the predicted microRNAs （miRNAs） targeting the affected genes. To this end we injected fertile eggs with either 0.5 μg of recombinant murine leptin or vehicle （PBS） before incubation.Results： Prenatally leptin-exposed chicks showed lower hatch weight, but higher liver weight relative to the body weight, compared to the control group. In ovo leptin treatment increased the hepatic content and serum concentration of leptin in newly hatched chickens. The hepatic contents of triglycerides （TG） and total cholesterol （Tch） were decreased, whereas the serum levels of TG, Tch and apolipoprotein B （ApoB） were increased. The hepatic mRNA expression of sterol regulator element binding protein 1 （SREBP-1c）, SREBP-2, hydroxy-3-methylglutaryl coenzyme A reductase （HMGCR） and cholesterol 7a-hydroxylase 1 （CYP7A1） was significantly up-regulated, as was the protein content of both SREBP-1 c and SREBP-2 in hepatic nuclear extracts of leptin-treated chickens. Moreover, out of 12 miRNAs targeting SREBP-1c and/or HMGCR, five were significantly up-regulated in liver of leptin-treated chicks, including gga-miR-200b and gga-miR-429, which target both SREBP-1c and HMGCR.Conclusions： These results suggest that leptin in ovo decreases hatch weight, and modifies hepatic leptin secretion and lipid metabolism in newly hatched broiler chickens, possibly via microRNA-mediated gene regulation.

Whole transcriptome analysis of RNA expression profiles reveals the potential regulating action of long noncoding RNA in lactating cows fed a high concentrate diet

Subacute ruminal acidosis(SARA)is a common metabolic disease in the dairy farming industry which is usually caused by an excessive amount of high concentrate diet.SARA not only threatens animal welfare but also leads to economic losses in the farming industry.The liver plays an important role in the distribution of nutritional substances and metabolism;however,a high concentrate diet can cause hepatic metabolic disorders and liver injury.Recently,noncoding RNA has been considered as a critical regulator of hepatic disease,however,its role in the bovine liver is limited.In this study,12 mid-lactating dairy cows were randomly assigned to a control(CON)group(40% concentrate of dry matter,n=6)and a SARA group(60% concentrate of dry matter,n=6).After 21 d of treatment,all cows were sacrificed,and liver tissue samples were collected.Three dairy cows were randomly selected from the CON and SARA groups respectively to perform whole transcriptome analysis.More than 20,000 messenger RNA(mRNA),10,000 long noncoding RNA(lncRNA),3,500 circular RNA(circRNA)and 1,000 micro RNA(miRNA)were identified.Furthermore,43 mRNA,121 lncRNA and 3 miRNA were differentially expressed,whereas no obvious differentially expressed circRNA were detected between the 2 groups.Gene Ontology(GO)annotation revealed that the differentially expressed genes were mainly enriched in oxidoreductase activity,stress,metabolism,the immune response,cell apoptosis,and cell proliferation.Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis showed that the deferentially expressed genes were highly enriched in the phosphatidylinositol 3 kinase(PI3) K-serine/threonine kinase(AKT)signaling pathway(P<0.05).According to KEGG pathway analysis,the differentially expressed lncRNA(DElncRNA)target genes were mainly related to proteasomes,peroxisomes,and the hypoxia-inducible factor-1 signaling pathway(P<0.005).Further bioinformatics and integrative analyses revealed that the lncRNA were strongly correlated with mRNA;therefore,it is reasonable to speculate that lncRNA potentially play important roles in the liver dysfunction induced by SARA.Our study provides a valuable resource for future investigations on the mechanisms of SARA to facilitate an understanding of the importance of lncRNA,and offer functional RNA information.

Maternal butyrate supplementation affects the lipid metabolism and fatty acid composition in the skeletal muscle of offspring piglets

Maternal sodium butyrate(SB)intake has important effects on offspring growth and development.This study aimed to investigate the impacts of maternal SB supplementation during gestation and lactation on fatty acid composition and lipid metabolism in the offspring skeletal muscle of pigs.Twenty sows(Yorkshire,parity 2 to 3)were assigned to the control group(diets without SB,n=10)and SB group(diets with 0.1%SB,n=10).The results showed maternal SB supplementation throughout gestation and lactation increased(P<0.05)body weight of offspring piglets at weaning.The concentrations of triglyceride in plasma and milk were enhanced(P<0.05).Maternal SB induced(P<0.05)lipid accumulation with increased expression of peroxisome proliferator activated receptorγ(PPARγ)by enrichment of the acetylation of H3 acetylation K27(H3 K27)in offspring skeletal muscle.Meanwhile,the concentrations of C18:2 n-6,C18:3 n-3,total polyunsaturated fatty acid(PUFA),n-6 PUFA and n-3 PUFA decreased(P<0.05)in skeletal muscle of weaning piglets derived from SB sows.Together,these results showed that maternal SB supplementation could influence offspring growth performance,lipid metabolism and fatty acid composition of the skeletal muscle.