Characterization of the evolution of free radicals and TALAs in linseed oil during heat treatment

Various studies have demonstrated that employing ESR spin trapping to detect free radicals yields valuable insights into the vulnerability of bulk oils to oxidation. Consequently, this method can be employed to assess and compare the oxidative stability of different samples. This study was conducted to investigate the production and transformation of free radicals and trans isomers in linseed oil when subjected to different temperatures and durations of heating. These analyses revealed that the peak levels of free radicals PBN adducts were evident in linseed oil heated to 120 °C, while these levels decreased within 90 min and were absent at a higher temperature of 180 °C. Free radical PBN adducts were readily degraded at 180 °C. Levels of heat-induced trans isomers rose in linseed oil samples with rising temperatures but began to degrade at temperatures exceeding 240 °C partially. The content examination of these trans isomers revealed that the double bonds located at positions 9 and 15 exhibited a higher susceptibility to isomerization compared to the double bond at position 12. Furthermore, the values of k and Ea indicated that the synthesis of tri-trans-α-linolenic acid (TALAs) was more challenging compared to double-TALAs, and double-TALAs were more challenging than single-TALAs. This was because the tri-TALAs has a higher Ea value than the mono-TALAs and double-TALAs. The study has demonstrated that subjecting linseed oil to high-temperature heating leads to the production of free radicals and trans isomers. And PBN radical adduct is unstable at 180 °C and the double bonds at positions 9 and 15 could be isomerized more easily than that at position 12. These results indicated that controlling the formation of free radicals and single-TALAs isomers may be the key way to reduce the trans isomers of linolenic acid during cooking oil heating. In the follow-up study, we found that VE, VK3, ethyl caffeic acid and resveratrol had significant inhibitory effects on the formation of TALAs of linolenic acid, and the highest inhibitory rate of resveratrol with 5% addition could be reached to 30.86%. The above substances can be applied to the thermal processing of linseed oil to prevent the formation of TALAs.

Regulating Function of miR-146a Derived from Bone Marrow Mesenchymal Stem Cell (BMSC) in Acute Lung Injury

This study assesses the mechanism of miR-146a derived from Bone marrow mesenchymal stem cell (BMSC) in acute lung injury. The model of ALI rats was established through endotracheal perfusion of LPS followed by analysis histological changes by HE staining. The source of BMSC was detected through flow cytometry and change of miRNA was detected through Array method. The miR-146a level in lung tissue was detected with RT-PCR and expression of Bcl-2, Bax and Capase-9 was detected with IF and Western Blot. A high expression of CD90 and CD105 was found in BMSC with negative CD11bc and CD34 level. 39 downregulated miRNAs and 20 upregulated miRNAs were found in ALI with miR-146a being the most significant. The apoptotic level induced with LPS could be restrained by miR-146a. In addition, miR-146a could upregulate Bcl-2 and downregulate Bax and Caspase-9. In conclusion, ALI could be restrained by the low expression of miR-146a.

Retraction Note: The carcinogenic complex lncRNA FOXP4-AS1/EZH2/LSD1 accelerates proliferation, migration and invasion of gastric cancer

The article "The carcinogenic complex lncRNA FOXP4-AS1/EZH2/LSD1 accelerates proliferation, migration and invasion of gastric cancer, by R.-Y. Chen, Q. Ju, L.-M. Feng, Q. Yuan, L. Zhang, published in Eur Rev Med Pharmacol Sci 2019; 23 (19): 8371-8376-DOI: 10.26355/eurrev_201910_19148-PMID: 31646567" has been retracted by the authors. After publication, the authors raised concerns about the reliability of the data used to conduct the study by stating that some data cannot be repeated by further research. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/19148.

Glucocorticoids Promote CCL20 Expression in Keratinocytes

Glucocorticoids (GC) are generally envisioned as immunosuppressive, but in conditions such as rosacea and perioral dermatitis they can lead to increased skin inflammation. In lung epithelia, GC promote expression of the pro-inflammatory cytokine CCL20, which contributes to steroid-resistant asthma. In the skin, CCL20 stimulates inflammation by recruiting Th17 T-lymphocytes and dendritic cells and is elevated in papulopustular rosacea. The objective of this study was to understand if and how glucocorticoids affect CCL20 expression in human keratinocytes. CCL20 expression was assessed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and ELISA. Selective inhibition of candidate genes and signaling pathways was performed using RNA interference and chemical inhibitors. The binding of activated glucocorticoid receptor to genomic DNA was determined by chromatin immunoprecipitation, and enhancer activity of genomic sequences was measured with a reporter assay. We found that GC treatment increased CCL20 expression in human keratinocytes and murine skin, both in the undisturbed state and with tumor necrosis factor-α (TNFα) stimulation. GC repressed pro-inflammatory signaling pathways including NFκB and p38/MAPK, but these inhibitory effects were opposed by the direct binding of activated glucocorticoid receptor to the CCL20 enhancer, promoting CCL20 expression. Viewed together, these findings demonstrate a mechanism by which GC induce expression of CCL20 in keratinocytes, which may contribute to the inflammation seen in steroid-exacerbated skin conditions.

The carcinogenic complex lncRNA FOXP4-AS1/EZH2/LSD1 accelerates proliferation, migration and invasion of gastric cancer

OBJECTIVE

To clarify the role of lncRNA FOX4-AS1 in the progression of gastric cancer (GC) via interacting with EZH2/LSD1.

PATIENTS AND METHODS

Relative level of FOXP4-AS1 in GC tissues and adjacent normal tissues was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The potential influences of FOXP4-AS1 on cellular behaviors of GC cells were evaluated via a series of functional experiments. Bioinformatics prediction, RNA immunoprecipitation (RIP) assay, and Western blot were conducted to verify the potential of EZH2/LSD1 as a target of FOXP4-AS1.

RESULTS

FOXP4-AS1 was upregulated in GC tissues relative to controls. Its level was higher in GC patients with stage III-IV than those with stage I-II. The survival rate was lower in GC patients presenting the high expression of FOXP4-AS1 compared with those presenting low expression. Transfection of sh-FOXP4-AS1 1# or sh-FOXP4-AS1 2# attenuated proliferative, migratory, and invasive abilities of AGS and BGC7901 cells. FOXP4-AS1 could bind to LSD1 and EZH2, and positively regulated their expression levels. Transfection of sh-LSD1 or sh-EZH2 reduced the proliferative ability of GC cells.

CONCLUSIONS

FOXP4-AS1 binds to EZH2/LSD1 to form a carcinogenic complex, thus accelerating GC cells to proliferate, migrate and invade.

An analysis of clinical characteristics and prognosis for patients with serum alpha-fetoprotein-positive gastric cancer

AIM

The aim of this analysis was to investigate the clinical characteristics and prognosis of patients with serum alpha-fetoproteinpositive gastric cancer (AFPGC) in order to improve the diagnosis and treatment.

METHODS

A retrospective analysis was performed on the clinical characteristics and survival data of patients with gastric cancer in our hospital between March 2007 and September 2012, to compare the clinical characteristics of patients with serum AFPGC to those of patients with serum AFP-negative gastric cancer. A Cox regression model was used to explore the prognosis factors for gastric cancer.

RESULTS

The 106 patients with serum AFPGC accounted for 8.5% (106/1253) of all the patients during the same period. There were poorer differentiation (64.2% vs. 54.0%), later clinical stage (83.1% vs. 48.6% at III+IV stage), larger tumor volume (78.3% vs. 57.9% with diameter>5 cm), and higher incidence of liver metastases (14.2% vs. 2.8%) and lymph node metastasis (76.4% vs. 52.7%) in patients with serum AFPGC than in those with serum AFP-negative gastric cancer (P<0.05). The 1-, 3-, and 5-year survival rates in patients with serum AFPGC were 52.8%, 31.3%, and 19.8%, respectively, with a median survival time of 14 months, and those in patients with serum alpha-fetoprotein-negative gastric cancer were 78.3%, 54.8%, and 36.8%, respectively, with a median survival time of 40 months. Multivariate Cox regression analysis showed that serum AFP positive (RR=2.70, 95% CI:1.50~4.87) was one of the risk factors of prognosis for patients with gastric cancer.

CONCLUSION

It is more malignant in patients with serum AFPGC than in those with serum alpha-fetoprotein-negative gastric cancer. There are later clinical stage, poorer differentiation, larger tumor volume, and higher incidence of metastasis to the liver and lymph nodes in patients with serum AFPGC, with low survival rate and poor prognosis.

Suppression of blood glucose level by a new fermented tea obtained by tea-rolling processing of loquat (Eriobotrya japonica) and green tea leaves in disaccharide-loaded Sprague-Dawley rats

BACKGROUND

In the field of food science, much interest has been focused on the development of alternative medicinal foods with the ability to regulate excess blood glucose level (BGL) rise. The authors have successfully developed a new fermented tea product (LG tea) by co-fermentation of loquat (Eriobotrya japonica) leaf and summer-harvested green tea leaf. The objective of this study was to examine the acute suppression effect of LG tea on BGL rise in disaccharide-loaded Sprague-Dawley (SD) rats and to evaluate its possible usage as an antidiabetic functional food material.

RESULTS

As a result of single oral administration of hot water extract of LG tea (50 mg kg(-1)) to maltose-loaded SD rats, BGL at 30 min was significantly decreased by 23.8% (P < 0.01) compared with the control. A corresponding reduction in serum insulin secretion was also observed. The ED(50) value of LG tea (50.7 mg kg(-1)) was estimated to be about 16-fold higher than that of the therapeutic drug acarbose (3.1 mg kg(-1)).

CONCLUSION

No significant change in BGL was observed when sucrose or glucose was administered, suggesting that the suppression effect of LG tea was achieved by maltase inhibition, not by sucrase inhibition or glucose transport inhibition at the intestinal membrane.

Hyperglycemia inhibits endothelial nitric oxide synthase activity by posttranslational modification at the Akt site

Endothelial nitric oxide synthase (eNOS) is activated by phosphorylation of serine 1177 by the protein kinase Akt/PKB. Since hyperglycemia-induced mitochondrial superoxide overproduction increases O-linked N-acetylglucosamine modification and decreases O-linked phosphorylation of the transcription factor Sp1, the effect of hyperglycemia and the hexosamine pathway on eNOS was evaluated. In bovine aortic endothelial cells, hyperglycemia inhibited eNOS activity 67%, and treatment with glucosamine had a similar effect. Hyperglycemia-associated inhibition of eNOS was accompanied by a twofold increase in O-linked N-acetylglucosamine modification of eNOS and a reciprocal decrease in O-linked serine phosphorylation at residue 1177. Both the inhibition of eNOS and the changes in its post-translational modifications were reversed by antisense inhibition of glutamine:fructose-6-phosphate amidotransferase, the rate-limiting enzyme of the hexosamine pathway, or by blocking mitochondrial superoxide overproduction with uncoupling protein-1 (UCP-1) or manganese superoxide dismutase (MnSOD). Immunoblot analysis of cells expressing myc-tagged wild-type human eNOS confirmed the reciprocal increase in O-linked N-acetylglucosamine and decrease in O-linked serine 1177 phosphorylation in response to hyperglycemia. In contrast, when myc-tagged human eNOS carried a mutation at the Akt phosphorylation site (Ser1177), O-linked N-acetylglucosamine modification was unchanged by hyperglycemia and phospho-eNOS was undetectable. Similar changes in eNOS activity and covalent modification were found in aortae from diabetic animals. Chronic impairment of eNOS activity by this mechanism may partly explain the accelerated atherosclerosis of diabetes.

Hyperglycemia inhibits endothelial nitric oxide synthase activity by posttranslational modification at the Akt site

Endothelial nitric oxide synthase (eNOS) is activated by phosphorylation of serine 1177 by the protein kinase Akt/PKB. Since hyperglycemia-induced mitochondrial superoxide overproduction increases O-linked N-acetylglucosamine modification and decreases O-linked phosphorylation of the transcription factor Sp1, the effect of hyperglycemia and the hexosamine pathway on eNOS was evaluated. In bovine aortic endothelial cells, hyperglycemia inhibited eNOS activity 67%, and treatment with glucosamine had a similar effect. Hyperglycemia-associated inhibition of eNOS was accompanied by a twofold increase in O-linked N-acetylglucosamine modification of eNOS and a reciprocal decrease in O-linked serine phosphorylation at residue 1177. Both the inhibition of eNOS and the changes in its post-translational modifications were reversed by antisense inhibition of glutamine:fructose-6-phosphate amidotransferase, the rate-limiting enzyme of the hexosamine pathway, or by blocking mitochondrial superoxide overproduction with uncoupling protein-1 (UCP-1) or manganese superoxide dismutase (MnSOD). Immunoblot analysis of cells expressing myc-tagged wild-type human eNOS confirmed the reciprocal increase in O-linked N-acetylglucosamine and decrease in O-linked serine 1177 phosphorylation in response to hyperglycemia. In contrast, when myc-tagged human eNOS carried a mutation at the Akt phosphorylation site (Ser1177), O-linked N-acetylglucosamine modification was unchanged by hyperglycemia and phospho-eNOS was undetectable. Similar changes in eNOS activity and covalent modification were found in aortae from diabetic animals. Chronic impairment of eNOS activity by this mechanism may partly explain the accelerated atherosclerosis of diabetes.

Transfection of human pancreatic islets with an anti-apoptotic gene (bcl-2) protects beta-cells from cytokine-induced destruction

Apoptosis has been identified as a mechanism of pancreatic islet beta-cell death in autoimmune diabetes. Proinflammatory cytokines are candidate mediators of beta-cell death in autoimmune diabetes, and these cytokines can induce beta-cell death by apoptosis. In the present study, we examined whether transfection of human islet beta-cells with an anti-apoptotic gene, bcl-2, can prevent cytokine-induced beta-cell destruction. Human islet beta-cells were transfected by a replication-defective herpes simplex virus (HSV) amplicon vector that expressed the bcl-2 gene (HSVbcl-2) and, as a control, the same HSV vector that expressed a beta-galactosidase reporter gene (HSVlac). Two-color immunohistochemical staining revealed that 95+/-3% of beta-cells transfected with HSVbcl-2 expressed Bcl-2 protein compared with 14+/-3% of beta-cells transfected with HSVlac and 19+/-4% of nontransfected beta-cells. The bcl-2-transfected beta-cells were fully protected from impaired insulin secretion and destruction resulting from incubation for 5 days with the cytokine combination of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma. In addition, the bcl-2-transfected islet cells were significantly protected from cytokine-induced lipid peroxidation and DNA fragmentation. These results demonstrate that cytokine-induced beta-cell dysfunction and death involve mechanisms subject to regulation by an anti-apoptotic protein, Bcl-2. Therefore, bcl-2 gene therapy has the potential to protect human beta-cells in pancreatic islets, or islet grafts, from immune-mediated damage in type 1 diabetes.

Transduction of non-dividing adult human pancreatic beta cells by an integrating lentiviral vector

Pancreatic islet cells are terminally differentiated endocrine cells and are refractory to stable infection by retroviral vectors, which require the breakdown of the nuclear membrane during cell division in order to insert the transgene into the host cell genome. Thus, attempts to render beta-cell allografts less immunogenic have had to rely on stable transfection of surrogate cells. Similarly, this problem has precluded the development of conditionally immortalized human beta cells for clinical allotransplantation. In this report, we demonstrate that adult human islet beta cells can be transduced by a new three-plasmid integrating lentiviral vector with an efficiency of 62 +/- 1.8 % at a multiplicity of infection (MOI) of 2.5 in vitro. This work makes genetic engineering of adult human pancreatic beta cells possible for the first time, allowing strategies to render beta-cell allografts non-immunogenic to be optimized and to creating conditionally immortalized human beta cells for clinical transplantation.

A model for transcription termination by RNA polymerase I

The transcription termination site for yeast RNA polymerase I requires not only an 11 bp binding site for Reb1p, but also about 46 bp of 5' flanking sequence. We propose that Reb1p bound to its site is part of a pause element, while the 5' flanking sequence contains a release element. Pausing requires little other than the DNA-binding domain of Reb1p and is not specific for polymerase I. The release element, however, can be polymerase specific. We propose a general model for eukaryotic transcription terminators in which termination occurs when a relatively nonspecific signal induces polymerase to pause in the context of a release element.

Ribosome synthesis during the growth cycle of Saccharomyces cerevisiae

We have measured the content of ribosomes, the rate of synthesis of ribosomal RNA, and the level of the mRNA for ribosomal proteins as a culture of Saccharomyces cerevisiae passes through the growth cycle. The transcription of both ribosomal RNA and ribosomal protein genes disappears at an unexpectedly early stage in the growth cycle, accompanied by a decline in the total RNA content of the culture by nearly 50% and a decline in the number of ribosomes per cell to less than 25% of the maximum value. During this time the cells continue to grow through more than two doublings, initially at the normal log growth rate, which then decline gradually for several hours. The data suggest that the cell can sense an unfavorable change within the medium and responds by employing regulation of both synthesis and degradation of its ribosomes. We conclude that the cell regulates ribosome synthesis and content according to its estimate of the potential for growth.

A bipartite DNA-binding domain in yeast Reb1p

The REB1 gene encodes a DNA-binding protein (Reb1p) that is essential for growth of the yeast Saccharomyces cerevisiae. Reb1p binds to sites within transcriptional control regions of genes transcribed by either RNA polymerase I or RNA polymerase II. The sequence of REB1 predicts a protein of 809 amino acids. To define the DNA-binding domain of Reb1p, a series of 5' and 3' deletions within the coding region was constructed in a bacterial expression vector. Analysis of the truncated Reb1p proteins revealed that nearly 400 amino acids of the C-terminal portion of the protein are required for maximal DNA-binding activity. To further define the important structural features of Reb1p, the REB1 homolog from a related yeast, Kluyveromyces lactis, was cloned by genetic complementation. The K. lactis REB1 gene supports active growth of an S. cerevisiae strain whose REB1 gene has been deleted. The Reb1p proteins of the two organisms generate almost identical footprints on DNA, yet the K. lactis REB1 gene encodes a polypeptide of only 595 amino acids. Comparison of the two Reb1p sequences revealed that within the region necessary for the binding of Reb1p to DNA were two long regions of nearly perfect identity, separated in the S. cerevisiae Reb1p by nearly 150 amino acids but in the K. lactis Reb1p by only 40 amino acids. The first includes a 105-amino-acid region related to the DNA-binding domain of the myb oncoprotein; the second bears a faint resemblance to myb. The hypothesis that the DNA-binding domain of Reb1p is formed from these two conserved regions was confirmed by deletion of as many as 90 amino acids between them, with little effect on the DNA-binding ability of the resultant protein. We suggest that the DNA-binding domain of Reb1p is made up of two myb-like regions that, unlike myb itself, are separated by as many as 150 amino acids. Since Reb1p protects only 15 to 20 nucleotides in a chemical or enzymatic footprint assay, the protein must fold such that the two components of the binding site are adjacent.

Topoisomerases and yeast rRNA transcription: negative supercoiling stimulates initiation and topoisomerase activity is required for elongation

Previous work has shown that rRNA synthesis is strongly inhibited in yeast top1-top2 double mutants. Here, we show that inactivation of yeast topoisomerases can have paradoxical effects on transcription by RNA polymerase I. For example, transcription of ribosomal minigenes on extrachromosomal plasmids is greatly stimulated in top1-top2 cells while accumulation of full-length endogenous rRNA is strongly inhibited. We present evidence for a mechanism that can partly account for these opposing effects on transcription. On the one hand, transcription initiation can be stimulated owing to an accumulation of negative superhelicity because polymerase I prefers to initiate on negatively supercoiled templates. Conversely, synthesis of full-length rRNA is inhibited owing to the fact that chain elongation requires a DNA relaxing activity.

Purification and characterization of the yeast rDNA binding protein REB1

In the yeast Saccharomyces cerevisiae, the ribosomal RNA genes are present in a single tandem array. A transcriptional enhancer element lies within the spacer region between each rRNA gene, 2.2 kilobases upstream from the transcription initiation site. We have identified previously two proteins, REB1 and REB2, that bind to specific sites within the enhancer (Morrow, B. E., Johnson, S. P., and Warner, J. R. (1989) J. Biol. Chem. 264, 9061-9068). REB1 binds also to a second, higher affinity site near the promoter, 210 base pairs upstream from the initiation site. This report describes the purification and further characterization of REB1. REB1 is a single polypeptide with an apparent molecular mass of 125,000 Da that binds to the sequence CCGGGTAA. It has been found to bind also within transcriptional control regions of several genes transcribed by RNA polymerase II, such as the UASG of the GAL1-GAL10 spacer. Immunoprecipitation analysis demonstrated that REB1 is phosphorylated.