• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.195-207
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• 2021

Species A rotaviruses (RVAs) replicate and assemble their immature particles within electron dense compartments known as viroplasms, where lipid droplets (LDs) interact with the viroplasm and facilitate viral replication. Despite the importance of LD formation in the life cycle of RVAs, the upstream molecules modulating LD formation remain unclear. This study aimed to find out the role of sterol regulatory element-binding proteins (SREBPs) in reprogramming of LD formation after RVA infection. Here, we demonstrate that RVA infection reprograms the sterol regulatory element-binding proteins (SREBPs)-dependent lipogenic pathways in virus-infected cells, and that both SREBP-1 and -2 transactivated genes, which are involved in fatty acid and cholesterol biosynthesis, are essential for LD formation. Our results showed that pharmacological inhibition of SREBPs using AM580 and betulin and inhibition of their downstream cholesterol biosynthesis (simvastatin for HMG-CoA reductase) and fatty acid enzymes (TOFA) negatively modulated the intracellular triacylglycerides and cholesterol levels and their resulting LD and viroplasm formations. Interestingly, pharmacological inhibition of SREBPs significantly reduced RVA protein synthesis, genome replication and progeny production. This study identified SREBPs-mediated lipogenic reprogramming in RVA-infected host cells, which facilitates virus replication through LD formation and its interaction with viroplasms, suggesting that SREBPs can be a potential target for the development of efficient and affordable therapeutics against RVA infection.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.2
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• pp.160-166
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• 2017

Objective: This study identifies single-nucleotide polymorphisms (SNP) or gene combinations that affect the flavor and quality of Korean cattle (Hanwoo) by using the SNP Harvester method. Methods: Four economic traits (oleic acid [C18:1], saturated fatty acids), monounsaturated fatty acids, and marbling score) were adjusted for environmental factors in order to focus solely on genetic effects. The SNP Harvester method was used to investigate gene combinations (two-way gene interactions) associated with these economic traits. Further, a multifactor dimensionality reduction method was used to identify superior genotypes in gene combinations. Results: Table 3 to 4 show the analysis results for differences between superior genotypes and others for selected major gene combinations using the multifactor dimensionality reduction method. Environmental factors were adjusted for in order to evaluate only the genetic effect. Table 5 shows the adjustment effect by comparing the accuracy before and after correction in two-way gene interactions. Conclusion: The g.3977-325 T>C and (g.2988 A>G, g.3977-325 T>C) combinations of fatty acid-binding protein4 were the superior gene, and the superior genotype combinations across all economic traits were the CC genotype at g.3977-325 T>C and the AACC, GACC, GGCC genotypes of (g.2988 A>G, g.3977-325 T>C).

• Journal of Life Science
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• v.31 no.9
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• pp.796-805
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• 2021

Hepatic endoplasmic reticulum (ER) stress contributes to the development of steatosis and insulin resistance. The components of unfolded protein response (UPR) regulate lipid metabolism. Recent studies have reported an association between ER stress and aberrant cellular lipid control; moreover, research has confirmed the involvement of sterol regulatory element-binding proteins (SREBPs)-the central regulators of lipid metabolism-in the process. However, the exact role of SREBPs in controlling lipid metabolism during ER stress and its contribution to fatty liver disease remain unknown. Here, we show that SREBP-1c deficiency protects against ER stress-induced hepatic steatosis in mice by regulating UPR, inflammation, and fatty acid oxidation. SREBP-1c directly regulated inositol-requiring kinase 1α (IRE1α) expression and mediated ER stress-induced tumor necrosis factor-α activation, leading to a reduction in expression of peroxisome proliferator-activated receptor γ coactivator 1-α and subsequent impairment of fatty acid oxidation. However, the genetic ablation of SREBP-1c prevented these events, alleviating hepatic inflammation and steatosis. Although the mechanism by which SREBP-1c deficiency prevents ER stress-induced inflammatory signaling remains to be elucidated, alteration of the IRE1α signal in SREBP-1c-depleted Kupffer cells might be involved in the signaling. Overall, the results suggest that SREBP-1c plays a crucial role in the regulation of UPR and inflammation in ER stress-induced hepatic steatosis.

• Journal of Life Science
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• v.28 no.10
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• pp.1233-1243
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• 2018

Sterol regulatory-element binding proteins (SREBPs) are a family of transcription factors that regulate lipid homeostasis and metabolism by controlling the expression of enzymes required for endogenous cholesterol, fatty acid (FA), triacylglycerol, and phospholipid synthesis. The three SREBPs are encoded by two different genes. The SREBP1 gene gives rise to SREBP-1a and SREBP-1c, which are derived from utilization of alternate promoters that yield transcripts in which distinct first exons are spliced to a common second exon. SREBP-2 is derived from a separate gene. Additionally, SREBPs are implicated in numerous pathogenic processes, such as endoplasmic reticulum stress, inflammation, autophagy, and apoptosis. They also contribute to obesity, dyslipidemia, diabetes mellitus, and nonalcoholic fatty liver diseases. Genome-wide analyses have revealed that these versatile transcription factors act as important nodes of biological signaling networks. Changes in cell metabolism and growth are reciprocally linked through SREBPs. Anabolic and growth signaling pathways branch off and connect to multiple steps of SREBP activation and form complex regulatory networks. SREBPs are activated through the PI3K-Akt-mTOR pathway in these processes, but the molecular mechanism remains to be understood. This review aims to provide a comprehensive understanding of the role of SREBPs in physiology and pathophysiology at the cell, organ, and organism levels.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.4
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• pp.638-645
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• 2010

The aim of this study was to investigate the effect of Taeeumjowuitanggagam-bang (TJV) on the mRNA expression of Sterol regulatory element binding proteins (SREBPs), Tumor necrosis factor-$\alpha$ (TNF-$\alpha$) and Interlukin-6 (IL-6) that are considered to play an important role in lipid and glucose metabolism. For diet-induced obese studies, we split mice into 2 groups. The low fat diet group (LFD, n=8) were supplied with general diet for 10 weeks and the high fat diet group (HFD, n=18) were supplied with 60 kcal% fat diet for 10 weeks. And then The HFD group, the diet-induced obese group, were divided into 3 groups ; a group supplied with normal saline, a group treated with TJV 200 mg/kg and a group treated with TJV 500 mg/kg. They were treated orally with TJV and measured their body weight every day during 10 weeks. After that, we measured mRNA expressions of TNF-$\alpha$, IL-6 and SREBP-1c in liver, and blood concentrations of glucose, total cholesterol and triglyceride too. The results are as follows. The TJV reduced glucose and total cholesterol of blood concentration. The TJV reduced the mRNA expressions of TNF-$\alpha$ and SREBPs in liver. However, We couldn't find the TJV effects on the mRNA expression of IL-6, triglyceride blood concentration, and body weight among groups. The TJV stained liver tissue less red than control group. These results suggest that TJV may be effective for regulation of lipid and glucose metabolism in liver.

• Natural Product Sciences
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• v.26 no.3
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• pp.200-206
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• 2020

The ability of the total extract from Physalis angulata; three fractions after partitioning with n-hexane, ethyl acetate (TBE), and water; and four withanolides (compounds 1 - 4) to phosphorylate 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells was evaluated. The TBE fraction (50 ㎍/mL) activated p-ACC and p-AMPK expression most strongly. Compounds 1 - 4 (10 μM) upregulated p-ACC expression at different levels. Compound 4 induced the most significant changes in p-AMPK expression, followed by 1 and 2. Sterol regulatory element-binding proteins (SREBPs) play a functional role in the transcriptional regulation of the lipogenic pathway, including fatty acid synthase (FAS) and ACC. The effects of compounds 2 and 4 (10 μM) on FAS and SREBP-1c expression under high glucose conditions (30 mM) in HepG2 cells were evaluated further. Both dose-dependently inhibited FAS and SREBP-1c expression as well as lipid accumulation (1 - 10 μM) were compared to high-concentration glucose control, which upregulated FAS and SREBP-1c. These results suggest that compounds 2 and 4 upregulate AMPK, suppress FAS and SREBP-1c, and have potential effects on glucose and lipid metabolism.

• Korean Journal of Poultry Science
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• v.43 no.1
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• pp.47-54
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• 2016

The aim of this study was to investigate the expression patterns of key genes involved in lipid metabolism in response to dietary Coenzyme Q10 (CoQ10) in hens. A total of 36 forty week-old Lohmann Brown were randomly allocated into 3 groups consisting of 4 replicates of 3 birds. Laying hens were subjected to one of following treatments: Control (BD, basal diet), T1 (BD+ CoQ10 100 mg/kg diet) and T2 (BD+ micellar of CoQ10 100 mg/kg diet). Birds were fed ad libitum a basal diet or the basal diet supplemented with CoQ10 for 5 weeks. Total RNA was extracted from the liver for quantitative RT-PCR. The mRNA levels of HMG-CoA reductase(HMGCR) and sterol regulatory element-binding proteins(SREBP)2 were decreased more than 30~50% in the liver of birds fed a basal diet supplemented with CoQ10 (p<0.05). These findings suggest that dietary CoQ10 can reduce cholesterol levels by the suppression of the hepatic HMGCR and SREBP2 genes. The gene expressions of liver X receptor (LXR) and SREBP1 were down regulated due to the addition of CoQ10 to the feed (p<0.05). The homeostasis of cholesterol can be regulated by LXR and SREBP1 in cholesterol-low-conditions. The supplement of CoQ10 caused a decreased expression of lipid metabolism-related genes including $PPAR{\gamma}$, XBP1, FASN, and GLUTs in the liver of birds (p<0.05). These data suggest that CoQ10 might be used as a dietary supplement to reduce cholesterol levels and to regulate lipid homeostasis in laying hens.