Increase of Fatty Acid Oxidation and VLDL Assembly and Secretion Overexpression of PTEN in Cultured Hepatocytes of Newborn Calf

Liang

et al. 2016

Sci Rep

In this study, we investigated the molecular regulatory mechanisms of milk protein production in dairy cows by studying the miRNAomes of five key metabolic tissues involved in protein synthesis and metabolism from dairy cows fed high-and low-quality diets. In total, 340, 338, 337, 330, and 328 miRNAs were expressed in the rumen, duodenum, jejunum, liver, and mammary gland tissues, respectively. Some miRNAs were highly correlated with feed and nitrogen efficiency, with target genes involved in transportation and phosphorylation of amino acid (AA). Additionally, low-quality forage diets (corn stover and rice straw) influenced the expression of feed and nitrogen efficiency-associated miRNAs such as miR-99b in rumen, miR-2336 in duodenum, miR-652 in jejunum, miR-1 in liver, and miR-181a in mammary gland. Ruminal miR-21-3p and liver miR-2285f were predicted to regulate AA transportation by targeting ATP1A2 and SLC7A8, respectively. Furthermore, bovine-specific miRNAs regulated the proliferation and morphology of rumen epithelium, as well as the metabolism of liver lipids and branched-chain AAs, revealing bovine-specific mechanisms. Our results suggest that miRNAs expressed in these five tissues play roles in regulating transportation of AA for downstream milk production, which is an important mechanism that may be associated with low milk protein under lowquality forage feed.Enhancing the protein content in milk is essential for improvement of milk quality in developing countries, especially under a lack of high-quality forage. Milk protein has been considered one of the best protein sources for humans 1 , especially whey protein, whose amino acids (AA) and associated compounds can provide nutrition and bioactive substrates for humans 2 . With the improvement of Chinese quality of life, total milk production has continuously increased, leading to the rapid development of the Chinese dairy industry, which has increased 12.8% annually on average since 2000 [3][4][5] . However, in China, milk production per cow is relatively low compared with that in the developed counties such as the USA 6 . The poor milk quality has been a huge concern due to its low nutrient content, especially protein 7 . Nitrogen (N) metabolism can directly impact milk protein yield and quality. N efficiency, the ratio of milk protein yield to crude protein intake, has been considered a key regulator for milk protein synthesis 8 . When N efficiency is low, a large proportion of N will be excreted through urine, reducing the N flow to the mammary gland for milk protein synthesis 9 . Therefore, N efficiency can also be estimated by measuring the content of milk urea N (MUN), with a lower MUN content representing higher N efficiency 10 . Feed efficiency, the ratio of milk production to dry matter intake, is also an important trait that indicates the efficiency of grocery nutrients transferred to the milk of dairy cows 11 . Therefore, lower feed and N efficiency can not only decrease the nutrients enriched in the milk but also increase the energy waste...

Section: Discussionmentioning

confidence: 99%

Systematic microRNAome profiling reveals the roles of microRNAs in milk protein metabolism and quality: insights on low-quality forage utilization

Liang

et al. 2016

Sci Rep

“…The virus titer ultimately reached 10 10 PFU/ml. The recombinant adenoviruses (AD-GFP- SREBP-1c) were used to infect hepatocytes, and the multiplicity of infections (MOI) were 25, 50, 100, 150, and 200 [9]. A fluorescence confocal microscope and flow cytometer were used to ensure the best AD-GFP-SREBP-1c concentration and the optimal time for GFP expression.…”

Section: Methodsmentioning

confidence: 99%

SREBP-1c Gene Silencing can Decrease Lipid Deposits in Bovine Hepatocytes Cultured <b><i>in Vitro</i></b>

Deng

Yin

et al. 2014

Cell Physiol Biochem

Self Cite

Background: Fatty liver is a major metabolic disorder that occurs during early lactation in high-producing dairy cows. Sterol regulatory element-binding protein-1c (SREBP-1c) is an important transcription factor that regulates lipid synthesis by regulating the expression of lipid metabolism genes. Methods: In this study, we reduced the expression of SREBP-1c by adenovirus-mediated SREBP-1c with a low expression vector (AD-GFP-SREBP-1c) to study the effects of SREBP-1c on lipid deposits in bovine hepatocytes. The expression levels and enzyme activities of SERBP-1c and its target genes were determined by real-time PCR, western blot, and ELISA. Results: These results showed that Ad-GFP-SREBP-1c could inhibit SREBP-1c expression. The expression of the lipid synthesis enzyme acetyl-CoA carboxylase (ACC) was down-regulated. The expression levels of the lipid oxidation enzymes long-chain fatty acyl-COA synthetase (ACSL-1), carnitine palmitoyltransferase І (CPT-І), carnitine palmitoyltransferase II (CPT- II), and β-hydroxyacyl-CoA-DH (HADH) were significantly elevated. Furthermore, the expression levels of factors involved in the assembly and transport of very low-density lipoproteins (VLDLs), such as apolipoprotein B100 (ApoB), apolipoprotein E (ApoE), and microsomal triglyceride transfer protein (MTTP) were decreased comparison with the negative control and the blank control groups, but the low-density lipoprotein receptor (LDLR) was elevated. The concentrations of TG (triglyceride) and VLDL were also reduced. Conclusion: These data suggest that low SREBP-1c expression can decrease lipid synthesis, increase lipid oxidation, and decrease the TG and VLDL content in bovine hepatocytes.

“…At the pathway level, the PTEN-AKT pathway is required for the initiation of lactation through the induction of autocrine prolactin (Chen et al, 2012 ). In addition, PTEN has been shown also to play a vital role in regulating fatty acid metabolism (Fu et al, 2012 ).…”

Section: Plausible Candidate Genes Underlying Css Regionsmentioning

confidence: 99%

An interpretive review of selective sweep studies in Bos taurus cattle populations: identification of unique and shared selection signals across breeds

2015

This review compiles the results of 21 genomic studies of European Bos taurus breeds and thus provides a general picture of the selection signatures in taurine cattle identified by genome-wide selection-mapping scans. By performing a comprehensive summary of the results reported in the literature, we compiled a list of 1049 selection sweeps described across 37 cattle breeds (17 beef breeds, 14 dairy breeds, and 6 dual-purpose breeds), and four different beef-vs.-dairy comparisons, which we subsequently grouped into core selective sweep (CSS) regions, defined as consecutive signals within 1 Mb of each other. We defined a total of 409 CSSs across the 29 bovine autosomes, 232 (57%) of which were associated with a single-breed (Single-breed CSSs), 134 CSSs (33%) were associated with a limited number of breeds (Two-to-Four-breed CSSs) and 39 CSSs (9%) were associated with five or more breeds (Multi-breed CSSs). For each CSS, we performed a candidate gene survey that identified 291 genes within the CSS intervals (from the total list of 5183 BioMart-extracted genes) linked to dairy and meat production, stature, and coat color traits. A complementary functional enrichment analysis of the CSS positional candidates highlighted other genes related to pathways underlying behavior, immune response, and reproductive traits. The Single-breed CSSs revealed an over-representation of genes related to dairy and beef production, this was further supported by over-representation of production-related pathway terms in these regions based on a functional enrichment analysis. Overall, this review provides a comparative map of the selection sweeps reported in European cattle breeds and presents for the first time a characterization of the selection sweeps that are found in individual breeds. Based on their uniqueness, these breed-specific signals could be considered as “divergence signals,” which may be useful in characterizing and protecting livestock genetic diversity.