Hepatic gene expression in multiparous Holstein cows treated with bovine somatotropin and fed n-3 fatty acids in early lactation

Dietary lipid during the transition period to manipulate subcutaneous adipose tissue peroxisome proliferator-activated receptor-γ co-regulator and target gene expression

Objectives were to determine adipose tissue mRNA expression of peroxisome proliferator-activated receptor (PPAR)γ co-regulators, target enzymes and transcription regulators, inflammation-related genes, and adipokines in response to dietary long-chain fatty acids (LCFA). From -21 through 10 d relative to parturition cows were fed no supplemental LCFA (control), saturated LCFA (SFAT; mainly 16:0 and 18:0), or fish oil (FO). Lipid was fed at 250 g/d prepartum or approximately 1.5 to 1.9% of the previous day's dry matter intake postpartum. Transcript profiling of 35 genes via quantitative PCR was conducted on biopsies (n=5 cows/diet) collected at -14 and 11 d from parturition. Despite lower dry matter intake with FO, pre- and postpartal blood nonesterified fatty acids, β-hydroxybutyrate, and liver triacylglycerol were unaffected by treatment but increased after calving regardless of diet. Prepartal expression of adipogenic/lipogenic transcription regulators [CEBPA, CEBPB, RXRA, KLF5, and MLXIPL (formerly ChREBP)] and co-regulators (CARM1, EP300, NCOA1, MED1, NCOR2, and NRIP1) was upregulated by FO and SFAT versus control, whereas most enzymes involved in lipogenesis/triacylglycerol synthesis (FASN, SCD, DGAT2, and LPIN1) had greater expression only with FO. Expression of most adipogenic/lipogenic genes decreased after parturition, but feeding SFAT led to sustained upregulation of CEBPA, CEBPB, RXRA, several PPAR-co-activators, and DGAT2 and SCD, suggesting maintenance of a pro-adipogenic/pro-lipogenic state with SFAT. The co-activator CREBBP was greater in cows fed lipid and did not decrease after parturition, suggesting ligand activation of PPARγ. The greater peripartal expression of NFKB1 and TBK1 due to dietary lipid was suggestive of a local inflammatory response. At amounts fed prepartum, both FO and SFAT were effective in upregulating the adipose tissue PPARγ-gene network. In contrast, only SFAT led to sustaining that response. Overall, the observed expression patterns are suggestive of an adipogenic regulatory mechanism particularly responsive to SFAT.

Expression of genes involved in hepatic carnitine synthesis and uptake in dairy cows in the transition period and at different stages of lactation

Background

In rodents and pigs, it has shown that carnitine synthesis and uptake of carnitine into cells are regulated by peroxisome proliferator-activated receptor α (PPARA), a transcription factor which is physiologically activated during fasting or energy deprivation. Dairy cows are typically in a negative energy balance during early lactation. We investigated the hypothesis that genes of carnitine synthesis and uptake in dairy cows are enhanced during early lactation.

Results

mRNA abundances of PPARA and some of its classical target genes and genes involved in carnitine biosynthesis [trimethyllysine dioxygenase (TMLHE), 4-N-trimethylaminobutyraldehyde dehydrogenase (ALDH9A1), γ-butyrobetaine dioxygenase (BBOX1)] and uptake of carnitine [novel organic cation transporter 2 (SLC22A5)] as well as carnitine concentrations in liver biopsy samples of 20 dairy cows in late pregnancy (3 wk prepartum) and early lactation (1 wk, 5 wk, 14 wk postpartum) were determined. From 3 wk prepartum to 1 wk postpartum, mRNA abundances of PPARΑ and several PPARΑ target genes involved in fatty acid uptake, fatty acid oxidation and ketogenesis in the liver were strongly increased. Simultaneously, mRNA abundances of enzymes of carnitine synthesis (TMLHE: 10-fold; ALDH9A1: 6-fold; BBOX1: 1.8-fold) and carnitine uptake (SLC22A5: 13-fold) and the concentration of carnitine in the liver were increased from 3 wk prepartum to 1 wk postpartum (P < 0.05). From 1 wk to 5 and 14 wk postpartum, mRNA abundances of these genes and hepatic carnitine concentrations were declining (P < 0.05). There were moreover positive correlations between plasma concentrations of non-esterified fatty acids (NEFA) and hepatic carnitine concentrations at 1 wk, 5 wk and 14 wk postpartum (P < 0.05).

Conclusions

The results of this study show for the first time that the expression of hepatic genes of carnitine synthesis and cellular uptake of carnitine is enhanced in dairy cows during early lactation. These changes might provide an explanation for increased hepatic carnitine concentrations observed in 1 wk postpartum and might be regarded as a physiologic means to provide liver cells with sufficient carnitine required for transport of excessive amounts of NEFA during a negative energy balance.

Nutrigenomics and personalized diets: What will they mean for food?

The modern food system feeds six billion people with remarkable diversity, safety, and nutrition. Yet, the current rise in diet-related diseases is compromising health and devaluing many aspects of modern agriculture. Steps to increase the nutritional quality of individual foods will assist in personalizing health and in guiding individuals to achieve superior health. Nutrigenomics is the scientific field of the genetic basis for varying susceptibilities to disease and the diverse responses to foods. Although some of these genetic determinants will be simple and amenable to personal genotyping as the means to predict health, in practice most will not. As a result, genotyping will not be the secret to personalizing diet and health. Human assessment technologies from imaging to proteomics and metabolomics are providing tools to both understand and accurately assess the nutritional phenotype of individuals. The business models are also emerging to bring these assessment capabilities to industrial practice, in which consumers will know more about their personal health and seek personal solutions.

Plasma FGF21 is elevated by the intense lipid mobilization of lactation

In many mammals, lactation success depends on substantial use of lipid reserves and requires integrated metabolic activities between white adipose tissue (WAT) and liver. Mechanisms responsible for this integration in lactation are poorly understood, but data collected in other conditions of elevated lipid use suggest a role for fibroblast growth factor-21 (FGF21). To address this possibility in the context of lactation, we studied high-yielding dairy cows during the transition from late pregnancy (LP) to early lactation (EL). Plasma FGF21 was nearly undetectable in LP, peaked on the day of parturition, and then stabilized at lower, chronically elevated concentrations during the energy deficit of EL. Plasma FGF21 was similarly increased in the absence of parturition when an energy-deficit state was induced by feed restricting late-lactating dairy cows, implicating energy insufficiency as a cause of chronically elevated FGF21 in EL. Gene expression studies showed that liver was a major source of plasma FGF21 in EL with little or no contribution by WAT, skeletal muscle, and mammary gland. Meaningful expression of the FGF21 coreceptor β-Klotho was restricted to liver and WAT in a survey of 15 tissues that included the mammary gland. Expression of β-Klotho and its subset of interacting FGF receptors was modestly affected by the transition from LP to EL in liver but not in WAT. Overall, these data suggest a model whereby liver-derived FGF21 regulates the use of lipid reserves during lactation via focal actions on liver and WAT.

Effect of dietary n-3 polyunsaturated fatty acid supplementation on bovine uterine endometrial and hepatic gene expression of the insulin-like growth factor system

Supplementation of cattle diets with n-3 polyunsaturated fatty acids (n-3 PUFA) has been suggested to have positive effects on fertility. In addition, the actions of the insulin-like growth factor (IGF) system both systemically and locally have been shown to influence reproductive processes. The objective of this study was to evaluate the effect of dietary n-3 PUFA supplementation on hepatic and endometrial expression of IGF signalling genes in cattle. Beef heifers were supplemented with a rumen protected source of either a saturated fatty acid (palmitic acid; CON) or high n-3 PUFA diet (n-3 PUFA) for 45 days before slaughter and tissue recovery. Transcription level of candidate IGF signalling genes was measured by reverse transcription quantitative real-time PCR (RT-qPCR) in total RNA isolated from uterine endometrial and liver tissue from seven CON and seven n-3 PUFA supplemented animals. Compared to controls, mRNA abundance in n-3 PUFA liver tissues was higher for IGF-2R, IGFBP-1 and IGFBP-5 (P < 0.05); lower for GHR-1A (P < 0.05); and unchanged for IGF-1, IGF-2, IGF-1R, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6, ALS and GHR(total) (P > 0.05). Compared to controls, mRNA abundance in n-3 PUFA endometrial tissues was higher for IGF-2, IGF-1R, IGF-2R and IGFBP-2 (P < 0.05); lower for IGF-1, IGFBP-3 and IGFBP-6 (P < 0.05); and unchanged for IGFBP-1, IGFBP-4, IGFBP-5 and GHR(total) (P > 0.05). Thus, dietary supplementation of cattle with n-3 PUFA affects transcription of genes involved in IGF signalling, in a tissue dependent fashion.