bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms Linking Mechanotransduction and Cell Metabolism
Authors: DeMali Kris , Salvi Alicia , Bays Jennifer 
Published: April 2020

External forces are sensed by cell surface adhesion receptors, such as E‐cadherin, and trigger robust actin cytoskeletal rearrangements that allow the cell to withstand the force. These actin rearrangements are energetically costly and require approximately half of the ATP in a cell. Previous work in our laboratory demonstrated that in response to force, E‐cadherin signals for enhanced energy production by stimulating AMP‐activated protein kinase (AMPK). AMPK triggers glucose uptake and its oxidation to ATP thereby providing the energy necessary for actin cytoskeletal remodeling. How mechanical force stimulates glucose uptake remains completely unexplored. In this study, we identify glucose transporter‐1 (GLUT1) as a force‐sensitive protein that is highly enriched in the plasma membrane in cells under tension. GLUT1 is necessary for the uptake of glucose and the reinforcement of the actin cytoskeleton that occurs when E‐cadherin experiences force. Intriguingly, GLUT1 is recruited to the cell‐cell junctions and forms a complex with E‐cadherin via a novel linkage mediated by the spectrin adaptor protein, Ankyrin G. Loss of Ankyrin G binding to E‐cadherin inhibits GLUT1 retention to the membrane, glucose uptake, and reinforcement of the actin cytoskeleton in response to force. This study provides the first mechanism for how cell mechanics stimulates the uptake of glucose.Support or Funding InformationThis work is supported by NIH Grant #GM112805.
Toward the solution of the protein‐structure prediction problem
Authors: Zhang Yang 
Published: April 2020

Protein structure prediction aims to determine the spatial location of every atom in protein molecules from the amino acid sequence by computational modeling. Depending on whether homologous structures are found in the Protein Data Bank (PDB), protein structure prediction have been historically categorized into template‐based modeling (TBM) and template‐free modeling (FM, or ab initio folding). In this talk, we first review recent progress in computer‐based protein structure prediction and show that the problem can be solved in principle (but not yet realistically) by TBM in case that fold‐recognition algorithms could identify the best structural templates from the PDB. Next, we discuss protein structure prediction results in the most recent community‐wide blind CASP experiments, showing that new approaches combining ab initio folding and deep neural‐network contact and distance predictions, which are built on residue coevolution data from multiple sequence alignments, can result in consistent and successful folding of proteins with sequence longer than 200–300 amino acids with a root‐mean‐square deviation below 3–4 Angstroms. This progress essentially breaks through the 50‐years‐old modeling border between TBM and FM and makes the success of high‐resolution structure prediction no longer relying on the PDB library. It also demonstrates the promise to solve the problem of protein structure prediction in a foreseeable future, by integrating deep machine learning techniques and the rapid advancement of genome sequencing databases, with the aid of advanced structure assembly simulation algorithms.Support or Funding InformationThis work is supported in part by the National Institute of General Medical Sciences (GM083107, GM116960), the National Institute of Allergy and Infectious Diseases (AI134678), and the National Science Foundation (DBI1564756, IIS1901191).
Lipid Droplet Proteome Dynamics and Lipotoxicity
Authors: Olzmann James 
Published: April 2020

Lipid droplets are ER‐derived neutral lipid storage organelles that function as cellular hubs of lipid metabolism, providing an “on demand” source of fatty acids for energy and sequestering fatty acids to protect cells from lipotoxic damage. Lipid droplet functions are controlled by associated integral and peripheral proteins. To understand the composition of lipid droplet proteomes, we recently developed a proximity labeling strategy to define high confidence lipid droplet proteomes. This approach uses lipid droplet‐targeted ascorbate peroxidase (APEX2), which enables the biotinylation of neighboring proteins in a spatially and temporally defined manner. Employing this method, we defined high confidence lipid droplet proteomes in multiple cell lines and identified pathways that impact lipid droplet proteome composition, uncovering a role for a ubiquitin‐dependent ER‐associated degradation (ERAD) pathway in the clearance of select lipid droplet proteins. A key function of lipid droplets is to sequester fatty acids to prevent lipotoxicity. To further understand how the cell responds to lipotoxic insults, we leveraged whole‐genome CRISPR‐Cas9 screens to dissect pathways that regulate lipid damage. For example, exploiting a synthetic lethal screening strategy, we discovered a new pathway that promotes cancer cell resistance to a regulated form of cell death known as ferroptosis, which involves the iron‐dependent accumulation of oxidatively damaged lipids. This study uncovered an unexpected role for non‐mitochondrial CoQ as a lipophilic antioxidant that prevents membrane damage. Together, our findings highlight the integration of systems level discovery approaches and cell biology methods as a powerful strategy to understand the mechanisms that regulate lipid droplets and lipotoxicity.Support or Funding InformationThis research was supported by grants from the National Institutes of Health (R00DK095921and R01GM112948) and from the American Heart Association (16GRNT30870005).
Cold‐Induced Lipokines in Energy Metabolism
Authors: Tseng Yu-Hua 
Published: April 2020

Obesity and metabolic syndrome are rapidly increasing worldwide, leading to high morbidity and mortality in type 2 diabetes, cardiovascular disease, renal failure, and even some cancers. Centered to these pathologies is the adipose tissue. In addition to the energy‐storing white adipose tissue, brown and brown‐like beige adipose tissue (BAT) are specialized for thermogenic energy expenditure. Due to the high capacity of BAT in consuming glucose and fatty acids to generate heat and dissipate energy and the presence of BAT in adult humans, increasing the amount or activity of BAT has been considered an appealing approach for the treatment or prevention of obesity and its related metabolic disorders. Besides energy dissipation, at least part of the beneficial effects of BAT is due to its secretory function and consequent capacity to affect metabolic functions in other tissues such as muscle, WAT, and liver. Thermogenic adipocytes can synthesize and release factors such as peptides, lipids, or other metabolites, which may act as endocrine, paracrine, or autocrine agents to regulate physiological functions required for adaptive thermogenesis. Cold exposure is one of the most efficient ways to activate BAT and increases energy consumption. Short‐term cold exposure leads to significant improvement in insulin sensitivity. By utilizing mass spectrometry‐based lipidomics, we have identified novel lipid mediators (i.e., lipokines) derived from BAT, whose concentrations are increased in the circulation of cold exposed mice and humans. These lipokines act as a marker and stimulator of thermogenic activity and negatively correlates with body mass index and insulin sensitivity. Mechanistic studies demonstrate that cold‐induced lipokines can regulate glucose and fatty acid metabolism. These findings provide novel therapeutic approaches for the treatment of metabolic diseases by mimicking cold exposure.Support or Funding InformationNIH (R01DK077097, R01DK102898, P30DK036836), US Army (W81XWH‐17‐1‐0428)
Local and systemic actions of hepatic fatty acid oxidation
Authors: Wolfgang Michael J. 
Published: April 2020

Mitochondrial long chain fatty acid beta‐oxidation is required for hepatic ketogenesis and gluconeogensis during fasting, starvation and times of low carbohydrate intake. The liver has a large capacity and dynamic range for fatty acid oxidation to facilitate ketogenesis and gluconeogenesis. To gain a better understanding of the roles of hepatic fatty acid oxidation on liver function, we generated mice with a hepatocyte‐specific knockout of Carnitine Palmitoyltransferase 2 (Cpt2L−/−), an obligate step in mitochondrial long‐chain fatty acid β‐oxidation. Mice with a loss in hepatic fatty acid oxidation were able to maintain systemic glucose homeostasis during a 24hr fast, but did not produce ketone bodies. Systemic energy homeostasis was largely maintained by adaptations in hepatic and systemic oxidative gene expression mediated in part by a robust hepatic transcriptional response. Open chromatin assessed by ATAC‐seq and histone H3K9 ChIP‐seq analysis revealed that many genes induced in fasted Cpt2L−/− mice exhibited Pparα regulatory sites. To understand the contribution of Pparα, we generated Pparα;Cpt2L−/− double knockout mice. The deletion of Pparα in Cpt2L−/− mice largely blunted this transcriptional response, demonstrating the requirement for Pparα. Triglyceride hydrolysis has been shown to be critical for Pparα‐mediated transcriptional control. To determine the requirement of hepatic triglyceride hydrolysis on the Cpt2L−/− transcriptional response, mice were generated with a liver‐specific defect in triglyceride hydrolysis (AtglL−/−) and fatty acid oxidation (AtglL−/−;Cpt2L−/− double knockout). The loss of Cpt2 or Atgl resulted in largely independent effects on hepatocyte morphology, intermediary metabolism and gene expression in response to fasting. However, high fat feeding revealed the interaction of Atgl and Cpt2 as the loss of only one of these genes results in steatosis but the loss of both components resulted in significant inflammation and fibrosis. These data suggest that defects in mitochondrial fatty acid oxidation induce an exaggerated fasting response that initiates lipid dependent transcription to mediate changes in local and systemic physiology.Support or Funding InformationThis work was supported in part by a National Institutes of Health grant R01DK116746 to M.J.W.
Comparison of serum cytokine measurement techniques between ELISA vs Multiplex
Authors: Ungaro Corey T. , Wolfe Anthony S. , Brown Shyretha D. 
Published: April 2020

Enzyme‐linked immunosorbent assay (ELISA) has been classically described as the gold standard for serum cytokine analysis. However, multiplex array technologies are increasing in popularity, likely because of their ability to analyze large numbers of analytes with low sample volume compared to ELISA. However, few studies have directly compared serum cytokine results from ELISA and multiplex analytical techniques. Therefore, the purpose of this study was to determine differences in serum cytokine concentrations between ELISA and Multiplex techniques. Blood samples were collected from the antecubital vein of professional American football players during a competitive season. After clotting, blood was centrifuged and three 300 μL aliquots of serum were frozen at −80°C. IL‐1β, IL‐6, and TNF‐α were measured using ELISA (EMD Millipore, Sigma Aldrich) and Multiplex (EMD Millipore, MagPix) kits. For standardization, one technician carried out the respective protocol under the same laboratory conditions on the same samples. Descriptive statistics are shown as mean ± SD. Coefficients of variation (CV%), paired samples t‐test with 95% CI, and Pearson’s product‐moment correlations were used to compare cytokine analysis techniques. Results indicated that serum cytokine concentrations were not comparable between ELISA and Multiplex analytical techniques. IL‐1β (n=15) displayed significant variability between techniques with a CV% of 119.9 with ELISA reading 36.8 ± 32.4 pg/mL, intra‐assay CV%= 7.6 and Multiplex showing 1.1 ± 1.2 pg/mL, intra‐assay CV%= 6.8. IL‐6 (n=33) demonstrated substantial variability between techniques with a CV% of 126.9 with ELISA reading 340.2 ± 460.5 pg/mL, intra‐assay CV%= 15.3 and Multiplex showing 11.8 ± 20.2 pg/mL, intra‐assay CV%= 4.8. For TNF‐α (n=36) all ELISA samples were below the detection limit of 0.31 with the Multiplex detecting 8.8 ± 3.2 pg/mL, intra‐assay CV%= 7.9. Moreover, paired samples t‐tests showed considerable mean differences between analysis techniques for IL‐1β (−35.8 pg/mL, (95% CI, −51.6 to −19.9) t(17) = −4.8, p < 0.001) and IL‐6 (−328.4 pg/mL (95% CI,−490.0 to −166.7), t(32)= −4.1, p < 0.001. Pearson’s correlation between ELISA and Multiplex was not significant for IL‐1β [r(13) = 0.44, p = 0.068] or IL‐6 [r(31) = 0.25, p = 0.157]. The results suggest that differences in blocking agents between both techniques may be the source of erraticism. According to the results from this study comparisons between analytical techniques should be avoided.Support or Funding InformationThis study was funded by and the authors are employed by the Gatorade Sports Science Institute, a division of PepsiCo, Inc. The views expressed in this abstract are those of the authors and do not necessarily reflect the position or policy of PepsiCo, Inc.
The Zn2+‐Transporter ZnT6 Plays Important Role on Regulation of Cytosolic Free Zn2+ Through Modulation of Mitochondrial Zn2+ in Hyperglycemic Cardiomyocytes
Authors: Tuncay Erkan , Turan Belma 
Published: April 2020

Free zinc ion (Zn2+), have physiological importance for mammals and is found to be less than 1‐nM in cytosol. However, intracellular free Zn2+ levels ([Zn2+]i) can increase dramatically under pathological conditions including hyperglycemia and cancer. Any increase in [Zn2+]i can also cause significant changes in several intracellular signaling pathways. However, that [Zn2+]i is well regulated by various ways in physiological conditions and that value can fluctuate dynamically in cardiomyocytes. It is accepted that there are two‐types of Zn2+‐transporters, one group of them is responsible Zn2+‐influx from extracellular space and/or organelles to cytosol (ZIPs) and the other group is responsible Zn2+‐efflux from cytosol (ZnTs). Since it is not known whether the Zn2+‐transporter ZnT6 has a role in the regulation of [Zn2+]i in cardiomyocytes under hyperglycemia, we used control and ZnT6 overexpressed H9c2 cells (rat embryonic ventricular cell lines) to investigate its role. In addition, H9c2 cells are incubated with normal (5.5‐mM; control) and high glucose (25‐mM; hyperglycemic) for 24‐h. Following the treatment, control and ZnT6‐overexpressed cells are transfected with Zn+2‐sensitive as well as cytosole, sarco/endoplasmic reticulum S(ER) or mitochondria targeted Förster resonance energy transfer (FRET) sensors to measure cytosolic, S(ER) and mitochondrial [Zn2+], respectively. Furthermore, we examined the mRNA, protein expression levels and intracellular localizations by using molecular, biochemical and immunofluorescence methods. Our results demonstrated that ZnT6 but not ZnT5 mRNA and protein level is increased under hyperglycemia, while ZnT6 overexpression caused increase of ZnT5 protein level. Our immunofluorescence/precipitation experiments showed that ZnT6 localized on mitochondria together with ZnT5 in H9c2 cells. Furthermore, our [Zn2+] measurements by fluorescence imaging showed that cytosolic and mitochondrial [Zn2+] are increased and S(E)R [Zn2+] is decreased in hyperglycemic H9c2 cells. We also found that, ZnT6‐overexpression caused mitochondrial [Zn2+] increase and decrease in cytosolic [Zn2+], without changing the S(E)R [Zn2+]. To understand the role of excess [Zn2+] on mitochondrial function, we used ZnT6 overexpressed or high Zn2+ incubated H9c2 cell lines to measure mitochondrial‐membrane‐potential (MMP), ROS and ATP production. We found that excess intracellular or mitochondrial [Zn2+] caused depolarization of MMP, increase in ROS and decrease in ATP production. Overall, our results showed that ZnT6 has a significant role on [Zn2+]i by modulating mitochondrial [Zn2+] and function in hyperglycemia.Support or Funding InformationTUBITAK‐SBAG‐117S386TUBITAK‐SBAG‐119S661
Ameliorative Effect of Gum Acacia on Water Pipe Smoke ‐ Induced Testicular Impairment in Mice
Authors: Ali Badreldin H. , Al-Salam Suhail , Al-Balushi Khalid M. , Al-Za’abi Mohammed H. , Nemmar Abdeerrahim 
Published: April 2020

We investigated some effects of water pipe smoke (WPS) exposure (30 min/day, for 30 days) in male mice, and the possible ameliorative of gum acacia (GA) coadministration thereon. Controls were exposed to air‐only (AE). Twenty‐four hours post last exposure, the levels of some plasma reproductive hormones, biochemical markers of inflammation, oxidative and nitrosative stress and testicular histopathology were assessed. The concentration of cotinine, the predominant metabolite of nicotine, was also measured in urine. WPS exposure induced a significant decreases in testosterone, estradiol, luteinizing hormone, and androgen binding protein. Inhibin B concentration was significantly increased. Plasma alkaline phosphatase, lipopolysaccharide binding protein, uric acid, and lactate dehydrogenase were all significantly increased following WPS exposure. In testicular homogenate, NF‐κB p65, Nrf2, interleukin‐1β, interleukin‐6, tumor necrosis factor –α, and transforming growth factor‐β1 were all significantly elevated after WPS exposure. WPS exposure decreased nitrite and total nitrite, glutathione reductase activity, and increased lipid peroxidation, cytochrome C, and 8‐Oxo‐2′‐deoxyguanosine. Histopathologically, there was slight reduction in the diameter of the seminiferous tubules with disorganized spermatogenesis. Cotinine concentration was significantly increased in the WPS‐exposed group compared with the control group. GA co‐administration mitigated the adverse actions of WPS measured. We conclude that daily exposure to WPS at the above dose induced damaging effects to the reproductive system in male mice, and that GA co‐administration mitigated the adverse actions of WPS measured.Support or Funding InformationSupported by a joint grant from Sultan Qaboos University and United Arab Emirates University (CL/SQU ‐ UAEU/18/01).
Eicosapentaenoic Acid Reduces Hepatic Steatosis Independently of UCP1
Authors: Albracht-Schulte Kembra , Wilson Savanna , Pahlavani Mandana , Ramalingam Latha , Festuccia William , Scoggin Shane , Moustaid-Moussa Naima 
Published: April 2020

Hepatic steatosis is characterized by excessive accumulation of triglyceride (TG). Mitochondrial membrane uncoupling proteins (UCPs) are potential targets for obesity treatment, given their ability to dissipate energy as heat. Previous studies in our lab have indicated that the omega‐3 polyunsaturated fatty acid, eicosapentaenoic acid (EPA), reduced obesity, inflammation and hepatic steatosis, and upregulated brown adipose tissue UCP1 protein in high fat (HF) fed mice housed at ambient temperature (22–23°C). However, EPA‐mediated improvements were attenuated and were independent of UCP1 when mice were housed in a thermoneutral environment (28–30°C). Thus, the objective of this work is to determine mechanisms of EPA‐mediated improvements in liver steatosis in UCP1 Knockout (KO) mice. Wild type (WT) and UCP1‐KO B6 mice were fed a HF diet with 36 g/kg AlaskOmega, 800mg/g fish oil of EPA (WT‐EPA, KO‐EPA) or without EPA (WT‐HF, KO‐HF) for 14 weeks. Mice were metabolically phenotyped during the feeding period, and histology and molecular analyses were performed in the liver after euthanasia. The KO‐HF group were highest in body weight, while KO‐HF, WT‐HF and WT‐EPA were comparable. Surprisingly, EPA attenuated weight gain in the KO‐EPA group compared to KO‐HF. Further, liver TG levels were significantly reduced in the KO‐EPA group compared to the KO‐HF. Consistent with this finding, EPA upregulated fatty acid beta‐oxidation markers only in the KO‐EPA group, indicated by significant increases in peroxisome proliferator activated receptor‐alpha (Ppara) and carnitine palmitoyltransferase (Cpt) 1a compared to KO‐HF. In conclusion, EPA rescued the detrimental effects of UCP1 deficiency in the livers of HF fed mice in a thermoneutral environment. Further studies are ongoing to dissect mechanistic basis for UCP1‐independent beneficial effects of EPA in liver steatosis. Our promising findings warrant further EPA supplementation studies in humans with obesity, given the limited activity of brown adipose tissue and downregulation of UCP1 in this population.Support or Funding InformationFunded by NIH/NCCIH grant #R15AT008879‐01A1 (N.M.M.)
Bioengineered Human Acellular Vessels as Dialysis Access Grafts
Authors: Niklason Laura 
Published: April 2020

Cardiovascular regenerative medicine has taken many avenues. One approach currently in clinical trials does not require any cells from the patient, and is an engineered tissue that is available “off‐the‐shelf”. Our approach to vascular engineering involves seeding allogeneic vascular cells onto a degradable substrate to culture vascular tissues in a biomimetic bioreactor. After a period of 8–10 weeks, engineered tissues are then decellularized to produce an engineered extracellular matrix‐based graft. The advantage of using allogeneic cells for graft production is that no biopsy need be harvested from the patient, and no patient‐specific culture time is required. These grafts are currently being tested in a Phase III clinical trial in Europe and in the US. Early experience supports the potential utility of this novel tissue engineered vascular graft to provide vascular access for hemodialysis.The decellularization approach has also allowed us to generate scaffolds to support whole lung regeneration. Using rat, porcine and human sources of organs, lungs have been subjected to a range of decellularization procedures, with the goal of removing a maximal amount of cellular material while retaining matrix constituents. Next‐generation proteomics approaches have shown that gentle decellularization protocols result in near‐native retention of key matrix molecules involved in cell adhesion, including proteoglycans and glycoproteins. Repopulation of the acellular lung matrix with mixed populations of neonatal lung epithelial cells results in regio‐specific epithelial seeding in correct anatomic locations. Survival and differentiation of lung epithelium is enhanced by culture in a biomimetic bioreactor that is designed to mimic some aspects of the fetal lung environment, including vascular perfusion and liquid ventilation. Current challenges involve the production of a uniformly recellularized scaffold within the vasculature, in order to shield blood elements from the collagenous matrix which can stimulate clot formation. In addition, we have developed methods to quantify barrier function of acellular and repopulated matrix, in order to predict functional gas exchange in vivo.Support or Funding InformationNIH R01 HL127386 (Niklason)