bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential association between irritable bowel syndrome and the gene encoding human intestinal sucrase‐isomaltase (LB131)
Authors: Diekmann Lena , Kuech Eva‐Maria , Phillip Ute , Distl Ottmar , Money Mary E. , Naim Hassan Y. 
Published: June 2021

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by abdominal pain and alterations in bowel pattern with a prevalence of 10‐15 % in humans. The molecular basis of IBS is not well understood.We sequenced the coding region of the sucrase‐isomaltase gene (SI) in a mother and her two children who suffer from IBS. The only polymorphism we found to be homozygous or heterozygous was Val15Phe (V15F, rs9290264, g.7526G>T, c.43G>T). We assessed the role of this exchange at the biochemical, cellular and functional levels by expressing SI containing V15F (SI‐V15F) in COS‐1 cells.The biosynthesis, glycosylation and folding of SI‐V15F were essentially comparable to those in wild type SI. The substitution of Val in the first α‐helix of the transmembrane domain of SI by a bulky Phe may have implications on the mode of association of SI with the inner leaflet of the membrane. For this, we investigated the association of SI‐V15F with lipid rafts by assessment of its solubility towards the non‐ionic detergent Triton X‐100 (TX‐100). In comparison to wild type SI, SI‐V15F is more soluble in TX‐100, i.e. less associated with lipid rafts. Cell surface biotinylation indicated that the trafficking of SI‐V15F to the plasma membrane is reduced by almost 20 % as compared to wild type SI. Finally, SI‐V15F revealed a 35 % decreased sucrase activity.Altogether, the combinatorial effects of reduced cell surface expression and enzymatic activity levels lead to a substantial decrease in the overall digestion capacity of SI‐V15F and strongly suggest an association between IBS and the substitution V15F.
Small transmembrane protein inhibitors of the platelet‐derived growth factor β receptor (LB215)
Authors: Petti Lisa , Talbert‐Slagle Kristina , Chacon Kelly , Hochstrasser Megan , DiMaio Daniel 
Published: June 2021

The platelet‐derived growth factor β receptor (PDGFβR) tyrosine kinase has been implicated in several cancers and is normally activated by binding of ligand to its extracellular domain. In addition, the small E5 transmembrane protein of bovine papillomavirus transforms cells by binding to the transmembrane domain of the PDGFβR and inducing receptor dimerization and activation. By screening retroviral libraries expressing hundreds of thousands of small proteins with randomized transmembrane domains, we identified artificial small transmembrane proteins termed “traptamers”, which specifically activate the PDGFβR and transform cells even though they have little or no sequence similarity to E5. A single conservative amino acid substitution in two traptamers converts them into inhibitors of the PDGFβR. The mutant traptamers bind to the PDGFβR and inhibit the mitogenic and transforming effects of PDGF and its homologue v‐sis by preventing phosphorylation of the receptor at particular tyrosine residues, suggesting that they may alter the conformation of the PDGFβR and/or its interaction with certain signaling proteins. These results validate a new strategy for isolating highly specific short transmembrane protein inhibitors of growth factor receptors, which could be used to gain new insight into growth factor receptor signaling and possibly as prototypes for the development of novel therapeutics.Grant Funding Source: Supported by a grant from the National Cancer Institute (CA37157)
Autophosphorylation by the Histidine kinase CheA (LB222)
Authors: Greenswag Anna , Crane Brian 
Published: June 2021

Chemotaxis is the signal transduction mechanism that allows bacteria to change direction in response to an external stimulus. Detection of an environmental stimulus by the receptors has a cascading effect leading to the flagellar motor changing direction. This results in the tumbling of the bacterium. The receptors form hexagonal lattices at the poles of cells. The histidine kinase CheA and coupling protein CheW are localized to the lattice to form the ternary complex. CheA, the principal enzyme in the chemotaxis signaling pathway, is a multi domain protein comprised of: P1‐histidine phosphotransfer, P2‐regulatory, P3‐dimerization, P4‐kinase, and P5‐regulatory. From previous studies it is known that the transfer of the γ‐phosphate of ATP occurs between the P1 and P4 domain, however how autophosphorylation activity is regulated is not completely understood.To comprehend this transient interaction, variants (ΔP2) of Thermotoga maritima CheA were generated. Small angle X‐ray scattering (SAXS) data has shown that spatial changes occur upon addition of an ATP analog. To determine relative activity of the ΔP2 variants or CheA domains radioisotope assays were used. Point mutations on the full length and ΔP2 CheA showed whether autophosphorylation occurs cis or trans in the dimer. Crosslinking between residues near the active sites in the P4 and P1 domains enabled isolation of the autophosphorylation transfer conformation. The crystal structure of P3P4 domains reveals a more active configuration of the P4 domain. Progress towards understanding how the domains interact to facilitate the transfer of the ATP γ‐phosphate is not clear and will be discussed.
Molecular mechanism underlying nuclear localization of EBP50 (LB225)
Authors: Lim Hooi‐Cheng , Jou Tzuu‐Shuh 
Published: June 2021

Ezrin‐radixin‐moesin (ERM)‐binding phosphoprotein of 50 kDa (EBP50) is a protein that is expressed at the apical surface of luminal organs. EBP50 consists of two tandem PDZ domains and a C‐terminal ezrin biding site, and this architecture allows EBP50 to organize molecules into functional complexes at the membrane periphery. Therefore, the studies of EBP50 were once focused on its regulatory roles at the plasma membrane, such as ion transporters activation, receptors recycling, and microvillar assembly. Later, EBP50 was found localized at the nucleus of cultured epithelial cells and carcinoma specimens, and interacted physically with nuclear proteins. However, the molecular mechanism that regulates nuclear localization of EBP50 remains unclear. A RNA interference‐based screening that coupled with image analysis was carried out to discover signaling pathways specific for trafficking of EBP50. The downstream effector of the mitogen‐activated protein kinase (MAPK) signaling pathway, p90 ribosomal S6 kinase alpha 1 (RSK1) was identified as a potential regulator, in which knockdown of RSK1 reduced the nuclear accumulation of EBP50. Furthermore, in vitro pull‐down assay and co‐immunoprecipitation approach had shown that RSK1 binds to the first PDZ domain of EBP50. RSK phosphorylates its substrate at RXRXXpS/T consensus phosphorylation motif. In vitro kinase assay showed that epidermal growth factor‐activated RSK1 phosphorylates EBP50, at the RXRXXpS/T motif. Collectively, our study identified RSK1 as a novel interacting partner of EBP50 that phosphorylates EBP50 at the RXRXXpS/T motif.Grant Funding Source: Supported by Taiwan National Science Council
Conformational switching in a copper‐sensing operon repressor (CsoR) (LB246)
Authors: Chang Feng‐Ming , Coyne H. , Fang Xianyang , Wang Yun‐Xing , Dann Charles , Giedroc David 
Published: June 2021

Copper is an essential transition metal for living organisms but it is detrimental in excess. The metalloregulatory protein copper‐sensing operon repressor (CsoR) in bacteria has evolved to prevent cytoplasmic copper toxicity. Cu(I)‐binding to tetrameric CsoRs mediates transcriptional derepression of copper resistance genes but the mechanism is unknown. A phylogenetic analysis of 227 DUF156 protein members including biochemically or structurally characterized CsoR/RcnR repressors reveals that Geobacillus thermodenitrificans (Gt) CsoR characterized here is representative of CsoRs from pathogenic bacilli Listeria monocytogenes and Bacillus anthracis. The 2.56 Å structure of Cu(I)‐bound Gt CsoR reveals that Cu(I) binding induces a kink in the α2‐helix between two conserved copper‐ligating residues and folds an N‐terminal tail (residues 12‐19) over the Cu(I) binding site. NMR studies of Gt CsoR reveal that this tail is flexible in the apo‐state with these dynamics quenched upon Cu(I) binding. Small angle X‐ray scattering (SAXS) experiments on an N‐terminally truncated Gt CsoR (∆2‐10) reveal that the Cu(I)‐bound tetramer is hydrodynamically more compact than is the apo‐state. A mutational analysis of residues critical to N‐terminal tail folding reveals that these residues function to stabilize the apoprotein‐DNA complex and/or control the extent of allosteric negative regulation of DNA binding by Cu(I), but to varying degrees. The mechanism of Cu(I)‐mediated allosteric switching in CsoRs is discussed.Grant Funding Source: Supported by NIH grant GM042569
Design of a Stimulus‐responsive Human Serum Albumin‐based Nanoparticle for Photodynamic Therapy (LB249)
Authors: Molina Anna , Benítez Marimar , Berríos Kiara , Griebenow Kai 
Published: June 2021

Photodynamic therapy (PDT) is a promising treatment for cancer. It relies on the accumulation of a photosensitizer (PS) drug in the target area and the subsequent irradiation with a light source to induce the formation of reactive oxygen species that cause cell death. The incorporation of these drugs in drug delivery systems (DDS) has proven to increase selectivity and overall efficiency of the therapy in vivo. We have synthesized a new DDS using human serum albumin nanoparticles (HSA NPs) of a discrete size as carriers. The PS drug Chlorin e6, which has proven to be effective for PDT, was covalently linked onto the NPs to prevent non‐selective release. Our NPs were stabilized with a redox‐sensitive crosslinker for targeted activation of the drug in a reducing environment, such as that of the cell cytoplasm. Absorbance and fluorescence spectroscopy experiments showed that the NPs disintegrated and that the PS photoquenching decreased in a 10 mM glutathione solution, resulting in the activation of the drug. The system was physically characterized in terms of size, shape and drug loading. The size obtained (280‐300 nm) was appropriate for accumulation in cancer tissue. Cell internalization and phototoxicity of the system were tested in HeLa cells by cell viability assays and confocal microscopy, showing efficient accumulation of the drug and dose‐dependent cytotoxicity. Our system demonstrated to be redox‐activated, with efficiency comparable to the free drug in vitro.Grant Funding Source: Supported by NIH Research Initiative for Scientific Enhancement (RISE) Program with grant number: 2R25GM061151‐12.
Geometric factors influencing hydrogen‐deuterium exchange: Detection of mobile water molecules in the peptide‐MHCI ‐ binding interface (LB291)
Authors: Jin Yining , Patil Sachin , von Grafenstein Hermann 
Published: June 2021

Hydrogen deuterium exchange (HDX) has long been used as an important technique to study conformational changes of proteins in solution, protein folding as well as protein ligand interactions. HDX is thought to detect exposure of protein backbone amide (bNH) hydrogens to solvent or internal water. However, it is not known how this exposure is defined in geometric terms, especially for internal water‐filled cavities. The experiments described here was designed to gain a better understanding of the influence of factors like distance and angle of orientation of bNH‐groups relative to internal water pockets. We used Major Histocompatibility Class I (MHCI)‐peptide complexes as a model to address this question. We expressed MHCI heavy and light chains and reconstituted MHCI‐peptide complexes with synthetic immunogenic peptides. We measured HDX using LC‐MS, and characterized structural parameters of water‐filled pockets with the help of computer programs like Pymol and Surfnet. We have successfully developed a model combining both distance and orientation of bNHs relative to nearby gaps which can predict HDX results and explain the HDX data achieved from the LC‐MS experiments. In addition to identifying geometric factors determining HDX, the project is also the first time attempting to correlate peptide‐MHC interface gap properties to the experimental H/D‐exchange in a quantitative manner. These results can be further applied to any other receptor ligand binding system which involves water molecules.Grant Funding Source: Supported by NIH and University of Toledo Financial Award
Differential regulation of adipokine levels after Bariatric surgery (LB345)
Authors: Wijayatunga Nadeeja , Sam Valerie , Blackledge Camille , Siriwardhana Nalin , Mancini Matthew , Mancini Gregory , LeMieux Monique , Moustaid‐Moussa Naima 
Published: June 2021

Bariatric surgery is known to cause significant weight loss, reduction in insulin resistance, cardiovascular disease and mortality. We hypothesized that adipose and systemic inflammation will be decreased post bariatric surgery. Our objective was to study changes in adipokine levels following bariatric surgery. We recruited patients undergoing Roux En Y gastric bypass and laparoscopic gastric band placement. Demographic data and both serum and adipose tissue samples were collected at the time of surgery, 2 weeks and 6 months post operatively. Luminex Human cytokine and adipokine kits were used along with adiponectin, Tumor Necrosis Factor‐α (TNF‐α), leptin and Monocyte Chemotractant Protein‐1 (MCP‐1) ELISAs to measure levels of these cytokines in serum and/or adipose tissues. Percentage changes in adipokines were calculated from time of surgery to each time point after surgery. There was a significant increase in adipose adiponectin at each post‐surgery time. Serum adiponectin showed an increasing trend by 6 months, but was not significant. Serum leptin, TNFα and MCP‐1 all showed decreasing trends from time of surgery to 6 months post surgery, but differences were not statistically significant. The percentage reduction for MCP‐1 at 6 months was significantly higher than for TNF‐α. These findings suggest that serum and adipose adipokine levels are differentially regulated by bariatric surgery. Additional studies are necessary to determine how these changes in tissue and circulating cytokine levels relate to various bariatric surgery outcomes.Grant Funding Source: PMERF (Physician’s Medical Education and Research Foundation, Knoxville, TN) and VPR and COHS Texas Tech University startup funds, Lubbock, TX
The Effect of Gender and National School Lunch Program Participation on Saturated Fat Content of Entrée Items Chosen by Elementary School‐Aged Students (LB379)
Authors: Anderson Annie , Granberg Ellen , Kropp Jaclyn , Peckham Janet , Condrasky Marge , Mroz Tom , Haley‐Zitlin Vivian 
Published: June 2021

□ The purpose of this study was to examine participants in a National School Lunch Program (NSLP) school district, and the effect of gender or participation in the NSLP on the selection of high saturated fat content entrée items by the elementary school students. Nutrition information provided to parents often does not include a profile of the fats offered in school lunch items. This was true of this study’s schools. However, new NSLP guidelines focus upon saturated and trans fat content in school lunches. The total kcal limit is <30%/total kcal, and saturated fat is <10%/total kcal, along with 0gms/serving trans fat. So, there is a need to monitor the fat profile of foods offered to ensure schools meet the current guidelines. As a part of a large plate waste study, all entrée items (79, 360) served in February 2013 in 11 elementary schools were analyzed for SFAs, MUFAs, PUFAs, trans fat, total fat and total kcal using “best fit” selection criteria with Nutritionist Pro TM nutritional analysis software based upon matching of nutrient content (kcal, CHO, protein, total fat, and sodium) from the school district and recipes of actual entrée items served. In the offer‐based school lunch service provided, three entrée items/day were served with a constant of vegetarian choice (consisting of cheese stick, yogurt, and cracker product) each day. Student numbers were 5,375 total; and a total of 41, 739 selections were made by males and 37, 621 by females. Total “paid”, “free” and “reduced” meals were 24,654; 50,366; and 4,340, respectively. Percentage of “free”, “reduced” and “paid” status meals for males were 63%, 5%, and 32% respectively and for females were 64%, 5.5%, and 30.5%. Point of Sale data collected during the same time period coupled with lunch dietary analysis data is being used to determine the effect of gender and/or participation in the free and reduced school lunch program on the selection of high saturated fat content entrée items by elementary school aged students and will be presented.□Grant Funding Source: CBBS Health Initiative Pilot Grant, Clemson University
Pharmacokinetics and plasma cellular anti‐oxidative effect of flavanols after oral intake formulating green tea with vitamin C and xylitol in healthy subjects (LB387)
Authors: Shim Soon‐Mi 
Published: June 2021

Soon‐Mi Shim Department of Food Science &amp; Technology and Carbohydrate Bioproduct Research Center, Sejong University, 98 Gunja‐dong, Gwangjin‐gu, Seoul, 143‐747, Republic of Korea The objective of the current study was to characterize pharmacokinetic, plasma cellular antioxidant activity and plasma metabolites of flavanols after oral intake of green tea formulating with vitamin C and xylitol in healthy subjects. Twelve healthy subjects took three green tea tablet (GT) with 100 mL of water and crossed‐over to intake three green tea tablet formulating vitamin C and xylitol (GTVX) with 100 mL of water following a 2‐week wash out period. Liquid Chromatography‐Mass Spectrometry (LC‐MS) was carried out for analysis flavanols in plasma taken at certain time points. The plasma flavanols’ concentration‐time profile for each study subject was determined by using a noncompartmental approach. Total Radical‐Trapping Antioxidant Parameter (TRAP) method was used for measuring total antioxidant activity (TAC) of plasma. Cmax, Tmax, AUC, and t2/1 of favanols in plasma after consumption of GTVX were 2.14 h, 5980.58 ng/mL, 18915.56 h*ng/mL, and 1.13 h, respectively, indicating that GTVX showed higher AUC than GT. The peak of trolox value was found at 3 and 0.5 hr after intake of GT and GTVX, respectively, revealing that they were different from Tmax of total flavanols. TAC of plasma was found to be significantly higher in GTVX than GT at each time point. Measured TAC of plasma was highly correlated with metabolites to gallated flavanols rather than total level of flavanols. Results from our study suggest that formulating green tea with vitamin C and xylitol could increase bioavailability of flavanols, resulting in enhanced biological function such as cellular anti‐oxidative effect.Grant Funding Source: Supported by Korea government (MEST)
Effect of Transforming Growth Factor‐β (TGF‐β) on Sox9 function and chondrocyte phenotype (LB40)
Authors: Perez Jessica , Seo HwaSeon , Serra Rosa 
Published: June 2021

TGF‐β enhances Sox9 protein expression as well as downstream targets that regulate extracellular matrix production in bovine articular chondrocytes (BACs). The extracellular matrix protein 3‐Prime‐Phoshoadenosine 5‐Prime‐Phosphosulfate Synthase 2 (Papss2) has been associated with spondyloepimetaphyseal dysplasias in humans and is required for proper sulfation of proteoglycans in cartilage. Our work and that of others has shown that TGF‐β can regulate Papss2 expression in articular cartilage. We aim to identify whether Sox9 is involved downstream of TGF‐β in the regulation of Papss2 mRNA expression.Using primary BACs in micromass cultures, we analyzed the effect of TGF‐β (5ng/ml) on chondrocyte phenotype, Sox9 protein expression, stability, cellular localization and activity. We also assessed the effect of TGF‐β and/or Sox9 overexpression on the mRNA expression of Papss2, Prg4 and GAPDH via quantitative real‐time PCR.We found that treatment with TGF‐β enhanced proteoglycan content and delayed chondrocyte hypertrophic differentiation in BACs. We also observed an increase in Sox9 protein levels and stability, without changes in mRNA. The increase in Sox9 protein correlated with enhanced Col2a‐reporter activity. Importantly, we found Papss2 to be upregulated via Sox9 when wild‐type (WT)‐Sox9 was overexpressed via adenoviral transduction (50 MOI/cell). Interestingly, treatment +/‐ TGF‐β when Sox9 was overexpressed did not further increase Papss2 mRNA, supporting the hypothesis that Sox9 works downstream of TGF‐ β. However, TGF‐β, but not Sox9, increased Prg4 mRNA expression, suggesting specificity of signaling. A GAPDH control was examined and remained unchanged in response to either treatment. The regulation of Papss2 by Sox9 represents a novel paradigm involving TGF‐β‐dependent signaling in articular chondrocytes.Grant Funding Source: Supported by NIAMS‐ NIH
Antioxidant Activity of Aster scaber Thunb. With Different Cooking Methods (LB409)
Authors: Kim Gun‐Hee , Choi Hye‐Young , Park Hee Sook 
Published: June 2021

Aster scaber Thunb. is a perennial herb of the compositae family and grows wild in the dry mountain regions of Korea. Aster scaber Thunb. possess many biological activities owing to their potential anticancer, anti‐inflammatory and antioxidant properties. This study investigated the antioxidant effect of Aster scaber Thunb.by various cooking methods and times. The Aster scaber Thunb. cooked by blanching, pan‐frying (1, 3, 5 and 10min) and microwaving (0.5, 1, 2 and 3min). The 70% ethanol extract of Aster scaber Thunb. was performed with ultrasound for 40 min and evaporated. Aster scaber Thunb. evaluated antioxidant activity based on protein degradation by reactive oxygen species including hypochlorite ion (CLO), hydroxyl radical (OH), peroxyl radical (AAPH) and peroxynitrite (ONOO). Our results showed that blanching of Aster scaber Thunb. against hypochlorite ion (CLO) has the highest protective effect by 95.08% at 3min. Antioxidant activity of blanced Aster scaber Thunb. against hydroxyl radical (OH) showed high myoglobin protective effects by 24.30% at 1min. Pan‐frying of Aster scaber Thunb. was showed the highest antioxidant activity against peroxyl radical (AAPH) by 31.98% at 1min. In case of peroxynitrite (ONOO), microwaved Aster scaber Thunb. showed the highest antioxidant effect by 73.87% at 0.5 min. With these results, we identified that the antioxidant capacity of Aster scaber Thunb. was affected by cooking method and time condition. Thus, Aster scaber Thunb. would be a useful dietary food to predict physiological effects.Grant Funding Source: This work was supported by a National