Low Expression of Sirtuin 1 in the Dairy Cows with Mild Fatty Liver Alters Hepatic Lipid Metabolism

Whole-Genome Resequencing Reveals Selection Signatures of Abigar Cattle for Local Adaptation

Over time, indigenous cattle breeds have developed disease resistance, heat tolerance, and adaptability to harsh environments. Deciphering the genetic mechanisms underlying adaptive traits is crucial for their improvement and sustainable utilization. For the first time, we performed whole-genome sequencing to unveil the genomic diversity, population structure, and selection signatures of Abigar cattle living in a tropical environment. The population structure analysis revealed that Abigar cattle exhibit high nucleotide diversity and heterozygosity, with low runs of homozygosity and linkage disequilibrium, suggesting a genetic landscape less constrained by inbreeding and enriched by diversity. Using nucleotide diversity (Pi) and population differentiation (FST) selection scan methods, we identified 83 shared genes that are likely associated with tropical adaption. The functional annotation analysis revealed that some of these genes are potentially linked to heat tolerance (HOXC13, DNAJC18, and RXFP2), immune response (IRAK3, MZB1, and STING1), and oxidative stress response (SLC23A1). Given the wider spreading impacts of climate change on cattle production, understanding the genetic mechanisms of adaptation of local breeds becomes crucial to better respond to climate and environmental changes. In this context, our finding establishes a foundation for further research into the mechanisms underpinning cattle adaptation to tropical environments.

Complementary hepatic metabolomics and proteomics reveal the adaptive mechanisms of dairy cows to the transition period

The transition period from late pregnancy to early lactation is a vital time of the lifecycle of dairy cows due to the marked metabolic challenges. Besides, the liver is the pivot point of metabolism in cattle. Nevertheless, the hepatic physiological molecular adaptation during the transition period has not been elucidated, especially from the metabolomics and proteomics view. Therefore, the present study aims to investigate the hepatic metabolic alterations in transition cows by using integrative metabolomics and proteomics methods. Gas chromatography quadrupole-time-of-flight mass spectrometry-based metabolomics and data-independent acquisition-based quantitative proteomics methods were used to analyze liver tissues collected from 8 healthy multiparous Holstein dairy cows 21 d before and after calving. In total, 44 metabolites and 250 proteins were identified as differentially expressed from 233 metabolites and 3,539 proteins detected from the liver biopsies during the transition period. Complementary functional analysis of different metabolites and proteins indicated the upregulated gluconeogenesis, tricarboxylic acid cycles, AA degradation, fatty acid oxidation, AMP-activated protein kinase signaling pathway, peroxisome proliferator-activated receptor signaling pathway, and ribosome proteins in postpartum dairy cows. In terms of the metabolites and proteins, glucose-6-phosphate, fructose-6-phosphate, carnitine palmitoyltransferase 1A, and phosphoenolpyruvate carboxykinase played a significant role in these pathways. The upregulated oxidative status may be accompanied by the pathways mentioned above. In addition, the upregulated glucagon and insulin signaling pathways also indicated the significant requirement for glucose in postpartum dairy cows. These outcomes, from the view of global metabolites and proteins, may present a better comprehension of the biology of the transition period, which can be helpful in further developing nutritional regulation strategies targeting the liver to help cows overcome this metabolically challenging time.

AAV-mediated BMP7 gene therapy counteracts insulin resistance and obesity

Type 2 diabetes, insulin resistance, and obesity are strongly associated and are a major health problem worldwide. Obesity largely results from a sustained imbalance between energy intake and expenditure. Therapeutic approaches targeting metabolic rate may counteract body weight gain and insulin resistance. Bone morphogenic protein 7 (BMP7) has proven to enhance energy expenditure by inducing non-shivering thermogenesis in short-term studies in mice treated with the recombinant protein or adenoviral vectors encoding BMP7. To achieve long-term BMP7 effects, the use of adeno-associated viral (AAV) vectors would provide sustained production of the protein after a single administration. Here, we demonstrated that treatment of high-fat-diet-fed mice and ob/ob mice with liver-directed AAV-BMP7 vectors enabled a long-lasting increase in circulating levels of this factor. This rise in BMP7 concentration induced browning of white adipose tissue (WAT) and activation of brown adipose tissue, which enhanced energy expenditure, and reversed WAT hypertrophy, hepatic steatosis, and WAT and liver inflammation, ultimately resulting in normalization of body weight and insulin resistance. This study highlights the potential of AAV-BMP7-mediated gene therapy for the treatment of insulin resistance, type 2 diabetes, and obesity.

Rutin Supplementation Reduces Oxidative Stress, Inflammation and Apoptosis of Mammary Gland in Sheep During the Transition Period

Rutin, a common dietary flavonoid, exhibits remarkable pharmacological activities such as antioxidant and anti-inflammatory functions. Metabolic stress in mammals during the transition period affects mammary gland health. The aim of this experiment was to evaluate the protective effect of rutin supplementing against metabolic stress in the mammary glands of sheep during the transition period, particularly after parturition. Transition Hu sheep (2-3 years old with 62.90 ± 2.80 kg) were randomly divided into three groups, the control group was fed a diet without rutin, while rutin (50 and 100 mg/kg body weight/day) was administered to the two treatment groups (-28 day to +28 day relative to parturition). Serum and blood samples were collected from jugular vein on days -14, -7, +1, +2, +7, +14, +21, +28 relative to parturition. Mammary tissue biopsy samples of four sheep from the treatment group were harvested on day +28 postpartum. Compared to that in the control group, rutin supplementation resulted in lower β-hydroxybutyrate (BHBA) while increasing the concentrations of non-esterified fatty acids (NEFA) and globulin after lactation. Furthermore, rutin treatment led to lower hydrogen peroxide (H2O2) and malonaldehyde (MDA) levels, resulting in increased catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and total antioxidant potential (T-AOC). Compared to that in the control group, rutin inhibits the mRNA expression of inflammatory markers such as tumor necrosis factor-α (TNF-α). In addition, rutin markedly downregulated the ratio of phosphorylated NF-κB p65 (p-p65) to total NF-κB p65 (p65). Meanwhile, rutin supplementation resulted in high mRNA abundance of the nuclear factor erythroid 2-like 2 (NFE2L2, formerly NRF2) and its target gene, heme oxygenase-1 (HO-1), which plays critical roles in maintaining the redox balance of the mammary gland. Furthermore, rutin treatment lowered the levels of various downstream apoptotic markers, including Bax, caspase3 and caspase9, while upregulating anti-apoptotic Bcl-2 protein. These data indicate the positive effect of rutin against inflammation, oxidative stress status, and anti-apoptotic activity in the mammary gland. The mechanism underlying these responses merits further study.

An Overview of Waste Milk Feeding Effect on Growth Performance, Metabolism, Antioxidant Status and Immunity of Dairy Calves

Waste milk (WM) is a part of the milk produced on dairy farms, which is usually unsuitable for human consumption. The WM contains transition milk, mastitis milk, colostrum, milk with somatic cells, blood (Hemolactia), harmful pathogens, pathogenic and antibiotic residues. Due to the high cost of milk replacer (MR), dairy farmers prefer raw WM to feed their calves. It has been well established that WM has a greater nutritive value than MR. Hence WM can contribute to improved growth, rumen development, and immune-associated parameters when fed to dairy calves. However, feeding raw WM before weaning has continuously raised some critical concerns. The pathogenic load and antibiotic residues in raw WM may increase the risk of diseases and antibacterial resistance in calves. Thus, pasteurization has been recommended as an effective method to decrease the risk of diseases in calves by killing/inhibiting the pathogenic microorganisms in the raw WM. Altogether, the current review provides a brief overview of the interplay between the positive role of raw WM in the overall performance of dairy calves, limitations of raw WM as a feed source and how to overcome these issues arising from feeding raw WM.

Sirtuin function and metabolism: Role in pancreas, liver, and adipose tissue and their crosstalk impacting bone homeostasis

Mammalian sirtuins (SIRT1-7) are members of the nicotine adenine dinucleotide (NAD+)-dependent family of enzymes critical for histone deacetylation and posttranslational modification of proteins. Sirtuin family members regulate a wide spectrum of biological processes and are best known for maintaining longevity. Sirtuins are well characterized in metabolic tissues such as the pancreas, liver and adipose tissue (AT). They are regulated by a diverse range of stimuli, including nutrients and metabolic changes within the organism. Indeed, nutrient-associated conditions, such as obesity and anorexia nervosa (AN), were found to be associated with bone fragility development in osteoporosis. Interestingly, it has also been demonstrated that sirtuins, more specifically SIRT1, can regulate bone activity. Various studies have demonstrated the importance of sirtuins in bone in the regulation of bone homeostasis and maintenance of the balance between bone resorption and bone formation. However, to understand the molecular mechanisms involved in the negative regulation of bone homeostasis during overnutrition (obesity) or undernutrition, it is crucial to examine a wider picture and to determine the pancreatic, liver and adipose tissue pathway crosstalk responsible for bone loss. Particularly, under AN conditions, sirtuin family members are highly expressed in metabolic tissue, but this phenomenon is reversed in bone, and severe bone loss has been observed in human subjects. AN-associated bone loss may be connected to SIRT1 deficiency; however, additional factors may interfere with bone homeostasis. Thus, in this review, we focus on sirtuin activity in the pancreas, liver and AT in cases of over- and undernutrition, especially the regulation of their secretome by sirtuins. Furthermore, we examine how the secretome of the pancreas, liver and AT affects bone homeostasis, focusing on undernutrition. This review aims to lead to a better understanding of the crosstalk between sirtuins, metabolic organs and bone. In long term prospective it should contribute to promote improvement of therapeutic strategies for the prevention of metabolic diseases and the development of osteoporosis.

Sirtuin 1 is involved in oleic acid-induced calf hepatocyte steatosis via alterations in lipid metabolism-related proteins

Sirtuin 1 (SIRT1), an NAD-dependent protein deacetylase, plays a central role in the control of lipid metabolism in nonruminants. However, the role of SIRT1 in hepatic lipid metabolism in dairy cows with fatty liver is not well known. Thus, we used isolated primary bovine hepatocytes to determine the role of SIRT1 in protecting cells against oleic acid (OA)-induced steatosis. Recombinant adenoviruses to overexpress (AD-GFP-SIRT1-E) or knockdown (AD-GFP-SIRT1-N) SIRT1 were used for transduction of hepatocytes. Calf hepatocytes isolated from five female calves (1 d old, 30 to 40 kg) were used to determine both time required and the lowest dose of OA that could induce triacylglycerol (TAG) accumulation. Analyses indicated that 0.25 mM OA for 24 h was suitable to induce TAG accumulation. In addition, OA not only led to an increase in TAG, but also upregulated mRNA and protein abundance of sterol regulatory element-binding transcription factor 1 (SREBF1) and downregulated SIRT1 and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PPARGC1A). Thus, these in vitro conditions were deemed optimal for subsequent experiments. Calf hepatocytes were cultured and incubated with OA (0.25 mM) for 24 h, followed by adenoviral AD-GFP-SIRT1-E or AD-GFP-SIRT1-N transduction for 48 h. Overexpression of SIRT1 led to greater protein and mRNA abundance of SIRT1 along with fatty acid oxidation-related genes including PPARGC1A, peroxisome proliferator-activated receptor alpha (PPARA), retinoid X receptor α (RXRA), and ratio of phospho-acetyl-CoA carboxylase alpha (p-ACACA)/total acetyl-CoA carboxylase alpha (ACACA). In contrast, it resulted in lower protein and mRNA abundance of genes related to lipid synthesis including SREBF1, fatty acid synthase (FASN), apolipoprotein E (APOE), and low-density lipoprotein receptor (LDLR). The concentration of TAG decreased due to SIRT1 overexpression. In contrast, silencing SIRT1 led to lower protein and mRNA abundance of SIRT1, PPARGC1A, PPARA, RXRA, and greater protein and mRNA abundance of SREBF1, FASN, APOE, and LDLR. Further, those responses were accompanied by greater content of cellular TAG and total cholesterol (TC). Overall, data from these in vitro studies indicated that SIRT1 is involved in the regulation of lipid metabolism in calf hepatocytes subjected to an increase in the supply of OA. Thus, it is possible that alterations in SIRT1 abundance and activity in vivo contribute to development of fatty liver in dairy cows.

Proteome analysis identified proteins associated with mitochondrial function and inflammation activation crucially regulating the pathogenesis of fatty liver disease

Background

Fatty liver disease prevalently occurs in commercial postpartum dairies, resulting in a worldwide high culling rate because of their subsequent limitations of production and reproduction performance.

Results

Fatty liver-specific proteome and acetylome analysis revealed that energy metabolism suppression closely associated with mitochondrial dysfunction and inflammation activation were shown to be remarkable biological processes underlying the development of fatty liver disease, furthermore, acetylation modification of proteins could be one of the main means to modulate these processes. Twenty pivotal genetic factors/genes that differentially expressing and being acetylation modified in liver were identified and proposed to regulate the pathogenesis of fatty liver dairies. These proteins were confirmed to be differentially expressing in individual liver tissue, eight of which being validated via immunohistochemistry assay.

Conclusions

This study provided a comprehensive proteome and acetylome profile of fatty liver of dairy cows, and revealed potential important biological processes and essential regulators in the pathogenesis of fatty liver disease. Expectantly, understanding the molecular mechanisms of the pathogenesis of fatty liver disease in dairies, as an animal model of non-alcoholic fatty liver disease (NAFLD) in human beings, which is a clinico-pathologically defined process associated with metabolic syndrome, could inspire and facilitate the development of efficacious therapeutic drugs on NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07950-2.

Glucose and Fatty Acid Metabolism of Dairy Cows in a Total Mixed Ration or Pasture-Based System During Lactation

In this study, we explored mechanisms related to glucose and fatty acid metabolism in Holstein–Friesian multiparous dairy cows during lactation under two feeding strategies. From 0 to 180 days postpartum, cows were fed total mixed ration (TMR) ad libitum (non-grazing group, G0) or grazed Festuca arundinacea or Medicago sativa and were supplemented with 5.4 kg DM/d of an energy-protein concentrate (grazing group, G1). From 180 to 250 days postpartum, all cows grazed F. arundinacea and were supplemented with TMR. Plasma samples and liver biopsies were collected at −14, 35, 60, 110, 180, and 250 days in milk (DIM) for metabolite, hormone, gene expression, and western blot analysis. Our results showed increased levels of negative energy balance markers: plasma non-esterified fatty acids (NEFA), liver triglyceride and plasma β-hydroxybutyrate (BHB) (P < 0.01), triglyceride and β-hydroxybutyrate concentration were especially elevated for G1 cows. Also, hepatic mRNA expression of gluconeogenic enzymes was upregulated during early lactation (P < 0.05). In particular, methymalonyl-CoA mutase expression was increased for G0 cows (P < 0.05) while pyruvate carboxylase (PC) expression was increased for G1 cows (P < 0.05), suggesting differential gluconeogenic precursors for different feeding strategies. Phosphorylation of AMP-activated protein kinase was increased in early lactation vs. late lactation (P < 0.01) and negatively correlated with PC mRNA levels. The positive association of gluconeogenic genes with proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) hepatic expression supported the importance of this transcription factor in glucose metabolism. The peroxisome proliferator-activated receptor alpha (PPARA) mRNA was increased during early lactation (P < 0.05), and was positively associated to PPARGC1A, carnitine palmitoyl-transferase 1, and hydroxymethylglutaryl-CoA synthase 2 (HMGCS2) mRNA expression. Alongside, hepatic mRNA expression of FABP was decreased for G1 vs. G0 cows (P < 0.05), possibly linked to impaired fatty acid transport and related to accumulation of liver triglycerides, evidencing G1 cows fail to adapt to the demands of early lactation. In sum, our results showed that metabolic adaptations related to early lactation negative energy balance can be affected by feeding strategy and might be regulated by the metabolic sensors AMPK, SIRT1, and coordinated by transcription factors PPARGC1A and PPARA.

Protein acetylation in mitochondria plays critical functions in the pathogenesis of fatty liver disease

BACKGROUND

Fatty liver is a high incidence of perinatal disease in dairy cows caused by negative energy balance, which seriously threatens the postpartum health and milk production. It has been reported that lysine acetylation plays an important role in substance and energy metabolism. Predictably, most metabolic processes in the liver, as a vital metabolic organ, are subjected to acetylation. Comparative acetylome study were used to quantify the hepatic tissues from the severe fatty liver group and normal group. Combined with bioinformatics analysis, this study provides new insights for the role of acetylation modification in fatty liver disease of dairy cows.

RESULTS

We identified 1841 differential acetylation sites on 665 proteins. Among of them, 1072 sites on 393 proteins were quantified. Functional enrichment analysis shows that higher acetylated proteins are significantly enriched in energy metabolic pathways, while lower acetylated proteins are significantly enriched in pathways related to immune response, such as drug metabolism and cancer. Among significantly acetylated proteins, many mitochondrial proteins were identified to be interacting with multiple proteins and involving in lipid metabolism. Furthermore, this study identified potential important proteins, such as HADHA, ACAT1, and EHHADH, which may be important regulatory factors through modification of acetylation in the development of fatty liver disease in dairy cows and possible therapeutic targets for NAFLD in human beings.

CONCLUSION

This study provided a comprehensive acetylome profile of fatty liver of dairy cows, and revealed important biological pathways associated with protein acetylation occurred in mitochondria, which were involved in the regulation of the pathogenesis of fatty liver disease. Furthermore, potential important proteins, such as HADHA, ACAT1, EHHADH, were predicted to be essential regulators during the pathogenesis of fatty liver disease. The work would contribute to the understanding the pathogenesis of NAFLD, and inspire in the development of new therapeutic strategies for NAFLD.