bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free fatty acid activates MMP‐1 and MMP‐3 through PPAR‐γ mitigation
Authors: Tsai Wei‐Ming , Tsai Kun‐Ling 
Published: November 2023

Obesity is positively related with the prevalence of coronary arterial disease (CAD). It is well known about the plasma concentrations of free fatty acid (FFA) are up‐regulated in cases with obesity. Oleic acid (OA) is known as the most abundant monounsaturated fatty acid in human circulatory system. Several pro‐atherosclerotic responses of OA had been established. Sirtuin 1 (SIRT1) acts a key role in regulation of the normal physical function in smooth muscle cells (SMCs). SIRT1 activation is thought as a novel approach to delay the progression of atherosclerotic injuries. However, the mechanism is still unclear as to whether OA affects SIRT1 expression and activity in SMCs. This study was designed to validate the hypothesis that OA treatment mitigates the expression level of SITR1 and its down‐stream genes, which is a negative regulator of NF‐κB pathway. We confirmed that OA treatment represses SIRT1 and PPAR‐γ levels in SMCs. Moreover, OA enhances transforming growth factor‐β1 (TGF‐b1) release by activation of NF‐κB. OA causes NO production by inducible nitric oxide synthase (iNOS) overexpression, thereby promoting the secretion of matrix metalloproteinases‐1 (MMP‐1) and matrix metalloproteinases‐3 (MMP‐3). Taken together, we suggested OA enhances MMPs activation by SIRT1 down‐regulation. MMPs activation had been shown to positively link with the atherosclerotic plaque generation, therefore, our findings might provide a novel route for developing new therapeutic treatments for FFAs‐related CAD.Support or Funding InformationMOST‐103‐2320‐B‐006‐050
Integrated Analysis of Posttranslational Modification Proteomes Reveals Interactions and Cell Cycle Regulatory Patterns in Toxoplasma gondii
Authors: Silmon de Monerri Natalie C , Yakubu Rama R , Weiss Louis M , Kim Kami 
Published: November 2023

Toxoplasma gondii is a highly successful protozoan parasite that senses and responds to stimuli by altering morphology at different life cycle stages. It is able to replicate inside nearly any type of nucleated cell, and therefore encounters different nutritional availabilities and environments that it must respond to. Given the role of protein posttranslational modifications (PTM) in signaling and sensing in eukaryotes, PTM are likely to play an important role in regulating how T. gondii responds to stimuli and makes life cycle stage transitions. Recent studies have mapped PTM proteomes in T. gondii, including phosphorylation, succinylation, palmitoylation and acetylation. Here, we aimed to gain a global understanding of the function of PTM in T. gondii, using published datasets and new unpublished datasets for ubiquitination, arginine methylation and O‐GlcNAcylation. By performing enrichment analysis using predefined gene sets, we identified pathways and compartments targeted by PTM in this organism. We show that many PTM in T. gondii occur on cell cycle‐regulated proteins whose expression peaks at specific time points during the cell cycle, representing checkpoint control points. Ubiquitination, phosphorylation and palmitoylation are also enriched in proteins upregulated at a critical time point in the transition between S and M phase. To understand how multiple PTM coregulate proteins in T. gondii, we used hypergeometric testing to score interactions between proteomes and interrogate the nature of their interactions. Surprisingly, we found a pool of proteins that are coregulated by both phosphorylation and arginine methylation, representing a novel interaction between these two modifications. A significant proportion of proteins are also coregulated by ubiquitination and palmitoylation. In current work, using protein interaction network analysis of PTM‐modified proteins, we aim to identify protein complex “hubs” that are regulated by multiple PTMs. Together, these analyses aim to detect pathways and hubs modified by PTM in parasites to sense and respond to stimuli.Support or Funding InformationNIH grants AI93220 (L.M.W.), AI092801 (K.K.), and AI087625 (K.K.)
Capacity of chlorogenic acid isomers to modulate oxidative and inflammatory responses in Caco‐2 human enterocyte‐like cells
Authors: Liang Ningjian , Kitts David 
Published: November 2023

Chlorogenic acids (CGAs) are esters formed between caffeic and quinic acids, and represent an abundant group of plant polyphenols present in the human diet. CGAs contain different isomers, including the major ones such as 5‐caffeoylqunic acid (5‐CQA), 3‐caffeoylqunic acid, 4‐caffeoylqunic acid, 3,4‐dicaffeoylqunic acid, 3,5‐dicaffeoylquinic acid, and 4,5‐dicaffeoylqunic acid. The antioxidant and anti‐inflammatory properties of 5‐CQA have been established in both cell and animal studies. However, little is known about the ability of other major CGA isomers to modulate oxidative and inflammatory stresses. In this study, we conducted a pre‐treatment experiment in which Caco‐2 cells were exposed to individual physiological relevant concentrations of CGA isomers for 24 hours and once removed were then challenged with oxidative and inflammatory stresses. We found that the pre‐incubation of CGA isomers promoted pro‐inflammatory cytokine, interleukin 8, and activated the nuclear translocation of nuclear factor kappa B (NF‐κB) pathway. The pre‐incubation did not activate nuclear factor‐E2‐related factor 2 (Nrf2) pathway. A co‐incubation experiment was conducted in which Caco‐2 cells were firstly exposed to individual CGA isomers for 24 hours. Then, fresh CGA isomers were added before cells were challenged with oxidative and inflammatory stresses. Herein, we found that the co‐incubation treatment of CGA isomers showed anti‐inflammatory effect by attenuating the secretion of IL‐8. This was accompanied with an increase in NF‐κB signaling. We also found that CGA co‐incubation treatment significantly increased Nrf2 signaling that corresponded to increased ratio of reduced glutathione to oxidized glutathione; both indicating a mitigated oxidative stress. We proposed that CGA isomers exert anti‐inflammatory activity by activating Nrf2 signaling, even though CGA isomer activated NF‐κB pathway at the early stage of response. Our results suggest that Nrf2 is a secondary event that participates in a later negative loop of NF‐kB regulation. Cross‐talk between NF‐κB and Nrf2 seems apparent in this case.Support or Funding InformationThis work was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant.
Arachidonic Acid Cascade Driven Neurotoxicity in Hypobaric Hypoxia: An invivo Study
Authors: Choudhary Richa , Katyal Anju 
Published: November 2023

BackgroundA continuous supply of oxygen to cerebral tissue is required for maintaining its homeostasis. Any interruption in delivery of oxygen leads to cerebral hypoxia related neuronal damage. . The growing bodies of evidences reveal that cerebral hypoxia induced at high altitude promotes the production of excessive ROS resulting in oxidative stress. Cerebral tissue is prone to oxidative stress damage because of high content of PUFA in their cell membrane and weak antioxidant defence system. Arachidonic acid(C20) is the most abundant form of PUFA which is present in brain. Under stress conditions arachidonic acid is metabolized by cyclooxygenase(COX‐2) and 12/15 Lipoxygenase in cerebral tissue which leads to the production of several prooxidant and anti‐inflammatory molecules. Experimental studies suggest that hypoxia induce oxidative burden which initiate the upregulation of arachodonic acid cascade enzyme 12/15LOX and COX‐2.MethodIn present study we aimed to investigate the modulatory role of 12/15 LOX and COX‐2 by using specific inhibitor of 12/15 LOX (baicalein) and COX‐2 (NS398) on neuronal damage induced by hypobaric hypoxia.ResultsAnimals subjected to hypobaric hypoxia in a specially designed decompression chamber experience cerebral hypoxia as confirmed by the elevated expression of HIF‐1a protein which is universal transcription factor that senses oxygen balance in cellular milieu. Further COX‐2 and 12/15 lipoxygenase gene and protein expression were significantly upregulated in hypoxia condition. Moreover histopathological study showed marked increase in death of neurons in hypoxia condition and inhibitor of 12/15 LOX and COX‐2 attenuated the neurotoxicity during cerebral hypoxia suggesting the contribution of arachidonic acid cascade in hypoxia condition. In addition to above biochemical studies like LDH assay, MDA assay for lipid peroxidation and nitric oxide levels revealed that oxidative stress mediated neuronal damage caused by hypoxia was attenuated significantly by 12/15 LOX and COX‐2 inhibitors confirming involvement of 12/15 LOX and COX‐2. TUNEL analysis confirmed the apoptotic form of cell death in hypoxia as dUTP labeled DNA fragments were significantly increased further 12/15LOX and COX‐2 enzyme inhibitor rescued the neuronal cells from apoptosis.ConclusionThe primary study using pharmacological inhibitors provide the strong evidence towards the contribution of arachidonic acid cascade in pathogenesis of cerebral hypoxia injury .Support or Funding InformationAuthors acknowledge Council for Scientific and Industrial Research (CSIR) India for financial assistance.
Chicken Broth AAC1 as a Dietary Supplement Inhibits Pain Transmission and Decreases Serum C‐Reactive Protein Levels In a Model of TMJ Disorder
Authors: Durham Paul , Hawkins Jordan 
Published: November 2023

ObjectiveThe goal of this study was to determine if the dietary inclusion of the commercially available chicken broth AAC1 could repress nocifensive behaviors and PKA expression associated with a clinically relevant model of temporomandibular joint (TMJ) disorder caused by prolonged jaw opening.BackgroundRoutine dental visits for molar extractions or root canals, or to the orthodontist can result in an injury to the TMJ or muscles of mastication if the jaw is held open for long periods of time or is opened to near maximal even for a short period of time. However, the pathophysiological and cellular mediators that underlie the development of chronic orofacial pain associated with TMJ disorder are not well understood. Chicken broth has been often thought of as having beneficial immune effects and may represent an innovative and safe alternative treatment for chronic inflammatory diseases.MethodsMale Sprague‐Dawley rats were used to investigate the effects AAC1 on behavioral and cellular changes associated with prolonged jaw opening. A surgical retractor was placed around the bottom and top incisors and the jaw held at near maximal opening for 20 minutes. Withdrawal responses to mechanical stimuli were determined following jaw opening for up to 7 days by applying calibrated von Frey filaments to the cutaneous area over the masseter. Some animals received 0.5% solid (w/v) AAC1 dissolved in their drinking water for two weeks prior to jaw opening. After 7 days, animals were euthanized and the upper spinal cord and trigeminal ganglia were removed to study changes in the expression of PKA utilizing immunohistochemistry. Serum samples were collected to determine the levels of C‐reactive protein using an ELISA.ResultsNear maximal jaw opening was induced a sustained increase in the number of nocifensive responses to mechanical stimuli over the masseter area for 7 days. This increased sensitivity correlated with increased levels of PKA expression in both the upper spinal cord and the trigeminal ganglia, and elevated serum levels of C‐reactive protein. Dietary inclusion of AAC1 was able to suppress nocifensive behaviors, PKA expression, and decreased levels of C‐reactive protein associated with prolonged jaw opening.ConclusionOur findings provide evidence that dietary inclusion of chicken broth AAC1 inhibits transmission of pain signals and represses levels of inflammatory mediators in serum and nerve cells and thus, may by a useful nutraceutical supplement to help manage inflammatory pain associated with TMJ disorder.Support or Funding InformationSupport provided by International Dehydrated Foods
Palmitoleate Protection Against Palmitate‐induced Cholangiocyte Lipoapoptosis is Sensitive to Pertussis Toxin
Authors: Natarajan Sathish Kumar , Walker Mary Anne , Toews Myron , Mott Justin L 
Published: November 2023

Non‐alcoholic fatty liver disease (NAFLD) patients have elevated plasma saturated free fatty acid (FFA) levels. Our recent work had demonstrated the role of FoxO3 and its downstream target, PUMA in FFA‐induced cholangiocyte lipoapoptosis and provided insights for biliary damage in a subset of NAFLD patients. Palmitoleate has been shown to be protective against FFA‐induced hepatocyte and pancreatic β‐cell lipoapoptosis and has potential as a dietary therapy. Here, we explored the mechanism of palmitoleate protection against cholangiocyte lipoapoptosis.MethodsApoptosis was assessed by TUNEL, characteristic nuclear morphology staining with DAPI, transmission electron microscopy, and caspase 3/7 activity assay. Cleaved PARP and cleaved caspase 3 were examined by Immunoblot.ResultsTreatment of rat primary cholangiocytes with palmitate (PA) induced lipoapoptosis as evidenced by a significant increase in TUNEL positive cells, apoptotic nuclear morphology changes and caspase 3/7 activity. We also show that PA treatment dramatically increased the levels of caspase substrate like cleaved PARP and cleaved caspase 3 in normal immortalized cholangiocytes, H69 and cell lines derived from cholangiocarcinoma, KMCH, Mz‐ChA‐1 and HuCCT cells. Treatment with palmitoleate, a mono unsaturated omega‐7 fatty acid mitigated cholangiocyte lipoapoptosis caused due to PA exposure. The protection offered by palmitoleate was abolished in cells treated with pertussis toxin, suggesting an involvement of G‐protein‐coupled receptor (GPCR) in mediating palmitoleate protection of against PA‐induced cholangiocyte lipoapoptosis. The specific GPCR that is responsible for the palmitoleate protection is now under investigation.In conclusion, palmitoleate protects PA‐induced cholangiocyte lipoapoptosis possibly via activating Gαi protein coupled receptor for cell survival.
Examining Interactions between Bacterioopsin and Carotenoid Biosynthetic Proteins in the Halophilic Archaeon Halobacterium salinarum
Authors: Plesa Alexandru M. , Peck Ronald F. 
Published: November 2023

Microbial opsins are complexes consisting of integral membrane proteins covalently bound to the retinal cofactor. These complexes undergo a conformational change in response to light and serve various functions including signaling and energy conservation. First identified in Archaea, microbial opsins have now been found in all three domains of life.Bacteriorhodopsin (BR), the first microbial opsin described, acts as a light‐driven proton pump in the halophilic Archaeon Halobacterium salinarum. When cellular respiration is inhibited due to low oxygen, BR generates a proton gradient that provides energy for ATP synthesis, active transport, and other cellular activities.Interestingly, it appears that the BO apoprotein itself plays an important role in regulating the production of the retinal cofactor. When not bound to retinal, BO inhibits the activity of lycopene elongase (Lye), an enzyme that catalyzes the committed step in the synthesis of bacterioruberins. Bacterioruberins are 50‐carbon carotenoids that integrate into the plasma membrane and are believed to increase membrane stability under conditions of osmotic stress. Since bacterioruberins have common precursors with retinal, the inhibition of Lye by BO likely acts to promote retinal synthesis at the expense of bacterioruberin synthesis.Haloferax volcanii is closely related to H. salinarum and inhabits similarly salty environments. H. volcanii produces bacterioruberins, but does not express any microbial opsins. We had previously determined that, despite a 65% identity between the two Lye homologs, the H. volcanii Lye is not inhibited by BO. This difference suggests that the two proteins have evolutionarily diverged to better suit the needs of the organisms. To identify the motifs in Lye that allow or prevent inhibition by BO, we constructed hybrid genes that included sections of both H. salinarum and H. volcanii lye. These hybrid genes were then placed into H. salinarum strains in the presence or absence of BO expression. BR and bacterioruberin levels were assayed to analyze the activity of Lye. Preliminary evidence suggests that only a small portion of the H. salinarum gene allows inhibition by BO.We have also begun to explore interactions between microbial opsins and Lye homologs from other organisms. Briefly, opsin and Lye homolog genes were expressed in H. volcanii and bacterioruberin production was monitored. Our initial findings indicate that the opsin from some organisms inhibit the activity of the Lye homolog from the same organism. Overall, our results suggest a widely‐distributed, and previously undescribed, activity for opsins.Support or Funding InformationFunding was provided by Colby College and the National Institutes of Health (Grant GM094735).
A Functional Relationship Between Plb1‐Mediated Phosphatidylcholine Turnover and Sphingolipid Homeostasis in Saccharomyces cerevisiae
Authors: Patton‐Vogt Jana , Anaokar Sanket , Brant Jacob , Jonik Benjamin , Nesbitt Nicole , Vera Michael 
Published: November 2023

Plb1 is a B‐type phospholipase that acts on phosphatidylcholine (PC). Localization studies have found Plb1 to be primarily at the endoplasmic reticulum and secreted from the cell. We have shown previously that Plb1 activity and expression are up‐regulated by loss of Ypk1, the yeast homolog of the human serum‐ and glucocorticoid‐ induced kinase (Sgk1). In addition, Plb1 overexpression is known to rescue the lethality of a ypk1ts ypk2Δ mutant. Ypk1 is a serine/threonine protein kinase that affects several membrane events, including plasma membrane flippase activity and sphingolipid homeostasis. Employing the serine palmitoyltransferse inhibitor, myriocin, and genetic mutants, we report that overexpression of Plb1 compensates for diminished sphingolipid biosynthesis in various strain backgrounds. To probe this result further, we examined the effect of Plb1 overexpression on signaling pathways known to affect, or be affected by, altered sphingolipid metabolism. Overexpression of Plb1 results in up‐regulation of the Unfolded Protein Response (UPR) and up‐regulation of INO1, a gene encoding inositol 3‐phosphate synthase, the rate limiting step in inositol biosynthesis. We are examining both the mechanism by which PC turnover up‐regulates the UPR and INO1 expression, as well as how that up‐regulation affects flux through sphingolipid biosynthesis. Our findings indicate a functional relationship between PC turnover and sphingolipid homeostasis.Support or Funding InformationNIH GM104876 to JPV
Novel Interactions of Yeast Glycerol‐3‐Phosphate Acyltransferases
Authors: Shabits Brittney , Tavassoli Marjan , Zaremberg Vanina 
Published: November 2023

Glycerol‐3‐phosphate acyltransferases (GPATs) catalyze the first committed and rate limiting step in the de novo synthesis of glycerophospholipids and neutral triacylglycerols. GPATs transfer an acyl group from acyl‐coenzyme A to the sn‐1 position of glycerol‐3‐phosphate to produce 1‐acyl glycerol‐3‐phosphate (lysophosphatidic acid). Lysophosphatidic acid can then be further acylated by a second acyltransferase to produce phosphatidic acid, a signalling lipid and key intermediate in lipid biosynthesis. In the model organism yeast Saccharomyces cerevisiae two GPATs, Gpt2 and Sct1, have been identified. Both are integral membrane proteins located to the endoplasmic reticulum (ER), differentially enriched in ER domains. Interestingly, we have shown that Gpt2 (but not Sct1) is responsible for channeling oleate (C18:1) into triacylglycerol that is eventually stored in lipid droplets. Furthermore, our studies on oleate metabolism unveiled novel ER structures that surround lipid droplets and are differentially enriched in Gpt2 while devoid of Sct1. In addition, we also uncovered a dynamic post‐translational regulation of Gpt2 and Sct1 through phosphorylation that responds to growth phase, carbon source and cellular GPAT imbalance. The aim of this work was to understand how GPAT interactions with other proteins contribute to their spatial distribution in the ER and to lipid synthesis partitioning. In order to identify potential protein interactors, Gpt2 and Sct1 were overproduced in cells deleted for endogenous GPATs and then isolated from lysates and microsomes using co‐immuno‐affinity and Ni‐NTA affinity chromatography purification techniques. Potential interactors co‐purifying with Gpt2 or Sct1 were identified through liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Our results suggest that Gpt2 and Sct1 differentially associate with ER sites where inter‐organelle transport of lipids occurs. Of importance are the contact sites between ER‐mitochondria, ER‐lipid droplets and the nuclear‐vacuolar junction.Support or Funding InformationThis work was supported by an operating grant from the Natural Sciences and Engineering Research Council of Canada to VZ.
Fourier Transform Infrared Spectroscopy Detection of Lipid Ion‐Pairing in the Staphylococcus aureus Plasma Membrane
Authors: Duran Andrea T , Marbach Helene , Rasul Bahar , Andrew Chan K. L. , Harvey Richard D 
Published: November 2023

Ion‐pairing between lipids in the Staphylococcus aureus plasma membrane has been hypothesized to aid survival of this bacterium at low pH and potentially facilitate antimicrobial drug resistance through increased lipid ordering. Fourier transform infrared spectroscopy (FTIR) is a useful and rapid technique that can potentially characterize the physical properties of phospholipid membranes. The purpose of this study was to determine if FTIR can detect ion‐pairing in natural lipids extracted from bacteria grown under different conditions and also in representative synthetic models. S. aureus reference strain 476 and methicillin‐resistant S. aureus (MRSA) strain A7 were cultured in Brain Heart Infusion broth at pH 7.4 and pH 5.5. The phospholipids were isolated from each of the samples using an organic solvent extraction process. Synthetic lipid models composed of binary mixtures of dipalmitoyl‐3‐aza‐dehydroxy‐lysyl‐phosphatidylglycerol (DP3adLPG) and dipalmitoylphosphatidylglycerol (DPPG) were also created, to mimic the compositions of the S. aureus plasma membrane at pH 7.4 (DP3adLPG/DPPG [30:70]) and pH 5.5 (DP3adLPG/DPPG [60:40]). Humidity chambers containing saturated NaCl solutions were created from T25 flasks, onto which two CaF2 FTIR windows were fixed, onto the inner face of one, the dried lipid sample films were deposited from solution in chloroform. Ion‐pairing was detected by FTIR analysis in both the lipid extracts and synthetic models, by analyzing the ν (PO4)− symmetric and ν (PO4)− asymmetric stretch regions of each FTIR spectrum. The DP3adLPG/DPPG [30:70] model had a ν (PO4)− symmetric (1056.41 cm−1) in between that of the DPPG (1052.93 cm−1) and DP3adLPG (1063.84 cm−1) standards, with a peak closer to that of DPPG. The ν (PO4)− symmetric stretch of the DP3ad‐LPG/DPPG [30:70] model suggests that both ion‐pairing between the two lipids took place, as well as self‐pairing within the headgroup of the DP3adLPG. These results are similar to the ν (PO4)− symmetric stretch observed in Strain A7 at pH 7.4 (1055.34 cm−1), demonstrating that, in terms of the lipid interactions, the synthetic model accurately represents the S. aureus membrane at pH 7.4. The results of the current study established that FTIR can be used to detect ion‐pairing in S. aureus lipid extracts. Furthermore, the similar ν (PO4)− symmetric in the DP3adLPG/DPPG models relevant to the lipid extracts at pH 7.4 and pH 5.5 provides physicochemical evidence that the synthetic DP3adLPG/DPPG models can accurately represent ion‐pairing within the S. aureus membrane.Support or Funding InformationSupported in part by grant MHIRT 2T37MD001368 from the National Institute on Minority Health and Health Disparities, National Institute of Health