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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

AIM2 accelerates the atherosclerotic plaque progressions in ApoE−/− mice

Highlights: • Our study demonstrated that AIM2 plays an important role in atherosclerosis. • We found that AIM2 could mediate GSDMD-N and pyroptosis in VSMCs for the first time. • We first found that AIM2 could affect ICAM-1 and macrophage recruitment in atherosclerosis. • We first found that ox-LDL can promote AIM2 expression through NF-κB signaling. Plaque formation is initiated and triggered by cell death in the vascular wall, which gradually leads to the progression of atherosclerosis. Pyroptosis is a newly discovered form of programmed cell death. Absent in melanoma 2 (AIM2), a member of the HIN-200 protein family, plays an important role in activating inflammasomes. However, the role and mechanism of AIM2 in atherosclerotic plaque progression has not been thoroughly elucidated to date. The effect of pyroptosis and the mechanism for this effect were investigated in apolipoprotein E-deficient (ApoE−/−) mice. AIM2 overexpression and inhibition were studied in ApoE−/− mice that were fed a high-fat diet. The specific role of AIM2 in vascular smooth muscle cells (VSMCs) was explored in vitro. The results showed that high fat diet increases the expression of AIM2, ICMA-1, GSDMD-N, which could be mediated by AIM2 expression. The plaque lesion area is lager with AIM2 overexpression. Moreover, TUNEL-positive cells were increased when AIM2 was overexpressed. With increased AIM2, macrophages were enhanced. In vitro studies showed that AIM2 and GSDMD-N expression correlated with ox-LDL levels in a concentration dependent manner. AIM2 expression is associated with NF-κB signaling activity and can be inhibited by NF-κB inhibitor. AIM2 mediated GSDMD activity through ASC, caspase1 pathway. EthD-III and TUNEL staining showed that AIM2 mediates pyroptosis in VSMCs. Our study suggests that AIM2 is not only a regular of inflammasome but also an active participant in atherosclerosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

GSK126 alleviates the obesity phenotype by promoting the differentiation of thermogenic beige adipocytes in diet-induced obese mice

Highlights: • GSK126, a chemical inducer of beige adipocytes, was identified in mice. • GSK126 induced the browning phenotype in subcutaneous and visceral WAT in mice. • Ezh2 and H3K27me3 promoted the differentiation of white adipocytes in mice. • Ezh2 and H3K27me3 inhibited the differentiation of beige adipocytes in mice. • Ezh2 and H3K27me3 played complex roles in brown adipocytes differentiation in mice. A close relationship between epigenetic regulation and obesity has been demonstrated in several recent studies. Histone methyltransferase enhancer of Zeste homolog 2 (Ezh2), which mainly catalyzes trimethylation of histone H3K27 to form H3K27me3 was found to be required for the differentiation of white and brown adipocytes in vitro. Here, we investigated the effects of the Ezh2-specific inhibitor GSK126 in a mouse model of obesity induced by a high-fat diet (HFD). We found that GSK126 treatment reduced body fat, improved glucose tolerance, increased lipolysis and improved cold tolerance in mice by promoting the differentiation of thermogenic beige adipocytes. Moreover, we discovered that GSK126 inhibited the differentiation of white adipocytes, and the decrease of Ezh2 enzymatic activity and H3K27me3 also changed the morphology of brown adipocytes but did not alter the expression of thermogenic genes in these cells. Our results indicated that GSK126 was a novel chemical inducer of beige adipocytes and may be a potential therapeutic agent for the management of obesity. Furthermore, they also prompted that Ezh2 and H3K27me3 play different roles in the differentiation of the white, brown, and beige adipocytes in vivo.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Ifi27 is indispensable for mitochondrial function and browning in adipocytes

Highlights: • Ifi27 is a brown fat-enriched gene and localizes to mitochondria. • The expression of Ifi27 is induced by β3-adrenergic agonist in adipose tissues. • Interferon-α signaling decreases Ifi27 level. • Ifi27 is physiologically required to maintain mitochondrial function and undergo browning. Brown adipose tissue (BAT) is specialized for energy expenditure, but the signaling pathways that regulate BAT metabolism and activity are incompletely understood. Interferon (IFN) signaling is a sophisticated defense mechanism to counteract viral infection. IFNs and interferon-stimulated genes (ISGs) are reported to exert profound effects on adipocytes. IFN-α inducible protein 27 (Ifi27/ISG12a) is a BAT-enriched gene, yet no any studies on its roles in BAT have been reported. Here, we show that Ifi27 protein localizes to mitochondria and the expression of Ifi27 can be induced by β3-adrenergic activation in adipose tissues. Knockdown of Ifi27 leads to reduced expression of key enzymes of tricarboxylic acid cycle (TCA), the subunits of electron transport chain (ETC) and uncoupling protein 1 (Ucp1) in brown and beige adipocytes. Moreover, the browning of subcutaneous white fat induced by β3-adrenergic agonist is also dramatically blocked. Ectopic expression of Ifi27 in brown adipocytes has the opposite effects. Together, these data indicate that Ifi27 regulates mitochondrial function and browning in adipocytes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Leptin regulates the expression of angiopoietin-like 6

Highlights: • High-fat diet results in increased hepatic ANGPTL6 expression. • Leptin treatment upregulates ANGPTL6 expression in hepatocytes. • Exercise training decreases serum ANGPTL6 as well as leptin. Angiopoietin-like 6 (ANGPTL6) is a hepatokine that antagonizes obesity and insulin resistance by increasing energy expenditure. Despite its beneficial effects on metabolism, human studies have shown a paradoxical increase in ANGPTL6 level in the serum of patients with metabolic diseases, which has been interpreted as a compensatory upregulation. However, the regulatory mechanism of ANGPTL6 remains unclear. Since upregulation of ANGPTL6 is induced on metabolic stress, we investigated the hepatic expression of ANGPTL6 by leptin, a representative adipokine of obesity. Mice on a high-fat diet showed increased serum leptin levels and hepatic Angptl6 expression, which were attenuated by exercise training. A single leptin injection also induced hepatic ANGPTL6 expression and increased serum ANGPTL6 levels. In an in vitro model using primary hepatocytes, leptin treatment significantly upregulated ANGPTL6 expression at the mRNA and protein levels, as well as the amount of secreted ANGPTL6 protein in conditioned media. Similarly, exercise training on human participants also showed diminished serum levels of leptin and ANGPTL6. Altogether, these results strongly indicated that hepatic ANGPTL6 expression was determined by leptin.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

DNA-binding activity of STAT3 increased in hypothalamus of DIO mice; the reduction of STAT3 phosphorylation may facilitate leptin signaling

Highlights: • The DNA-binding activity of STAT3 significantly increased, POMC expression decreased in the hypothalamus of DIO mice. • The reduction of STAT3 phosphorylation facilitated leptin-mediated POMC expression in cultured cells. • The DNA-binding activity of STAT3 and the proximal SBE of POMC promoter was essential to leptin-mediated POMC transcription. Leptin-mediated DNA-binding activity of STAT3 in hypothalamus plays crucial roles in the maintenance of energy homeostasis in lean mice; however its effects still remains unclear in case of leptin resistance in mice with diet induced obesity (DIO). In this study significant elevation of both basal and exogenously leptin-treated DNA-binding activity of STAT3 was detected using EMSA in the hypothalamus of male C57BL/6J mice fed high-fat diet for 10 wks, in concomitant with hyperleptinemia, high body weight, high fat mass, and hyperphagia as well as decreased POMC expression. The studies in vitro showed that both DNA binding activity and the proximal SBE of POMC promoter was essential to leptin-mediated POMC expression. However, the diminution of STAT3 phosphorylation, achieved by S3I-201 or a FoxO1 mutant, facilitated leptin-mediated POMC expression. The findings here demonstrated excess STAT3 activity negatively regulated POMC expression in hypothalamus of DIO mice, and suggested the limitation of STAT3 activity may promote leptin signaling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Biomass supply chain equipment for renewable fuels production: A review

The production of renewable fuels is a critical component of global strategies to reduce greenhouse gas (GHG) emissions. Moreover, the collection of raw materials for its production can provide added benefits such as reduction of wildfire risk, additional income for farmers, and decreased disposal costs. Although there is substantial literature on design and modeling of supply chains, the authors were unable to find a single reference with the information needed for the selection and cost estimation of each type of equipment involved in the supply chain. Therefore, the goal of this research is to gather information necessary for the construction and utilization of models that might drive the identification of a feasible supply chain to produce renewable fuels at a commercial scale. The primary objectives are to 1) understand the supply chain of critical feedstocks for renewable fuels production; 2) identify the equipment commercially available for collection and adequation of feedstock; and 3) consolidate information regarding equipment cost, energy consumption, and efficiency, as well as feedstock storage and transportation systems. This paper provides a compilation for five feedstock types studied for sustainable aviation fuel production: 1) agricultural residues and grasses, 2) forest residues, 3) urban wood waste, 4) oilseeds, 5) fats, oils & greases. All the technologies involved from the field to the gate of the preprocessing or conversion unit were reviewed. The information on fats, oils & greases supply chains and equipment purposely designed for forest thinning and pruning was very limited.

: Feedstock, Collection and Adequation, Renewable ↗
DOE OSTI2015

Examining confounding by diet in the association between perfluoroalkyl acids and serum cholesterol in pregnancy

Background: Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have consistently been associated with higher cholesterol levels in cross sectional studies. Concerns have, however, been raised about potential confounding by diet and clinical relevance. Objective: To examine the association between concentrations of PFOS and PFOA and total cholesterol in serum during pregnancy taking into considerations confounding by diet. Methods: 854 Danish women who gave birth in 1988–89 and provided a blood sample and reported their diet in week 30 of gestation. Results: Mean serum PFOS, PFOA and total cholesterol concentrations were 22.3 ng/mL, 4.1 ng/mL and 7.3 mmol/L, respectively. Maternal diet was a significant predictor of serum PFOS and PFOA concentrations. In particular intake of meat and meat products was positively associated while intake of vegetables was inversely associated (P for trend <0.01) with relative difference between the highest and lowest quartile in PFOS and PFOA concentrations ranging between 6% and 25% of mean values. After adjustment for dietary factors both PFOA and PFOS were positively and similarly associated with serum cholesterol (P for trend ≤0.01). For example, the mean increase in serum cholesterol was 0.39 mmol/L (95%CI: 0.09, 0.68) when comparing women in the highest to lowest quintile of PFOA concentrations. In comparison the mean increase in serum cholesterol was 0.61 mmol/L (95%CI: 0.17, 1.05) when comparing women in the highest to lowest quintile of saturated fat intake. Conclusion: In this study associations between PFOS and PFOA with serum cholesterol appeared unrelated to dietary intake and were similar in magnitude as the associations between saturated fat intake and serum cholesterol. - Highlights: • PFOS and PFOA have consistently been linked with raised serum cholesterol • Clinical relevance remains uncertain and confounding by diet has been suggested • The aim of this study was to address these issues in a cohort of 854 pregnant women • With detailed dietary information we found no indication of such confounding • As predictors cholesterol PFOSA and PFOA were similar to other known risk factors.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation

Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Evaluation of Functional Marrow Irradiation Based on Skeletal Marrow Composition Obtained Using Dual-Energy Computed Tomography

Purpose: To develop an imaging method to characterize and map marrow composition in the entire skeletal system, and to simulate differential targeted marrow irradiation based on marrow composition. Methods and Materials: Whole-body dual energy computed tomography (DECT) images of cadavers and leukemia patients were acquired, segmented to separate bone marrow components, namely, bone, red marrow (RM), and yellow marrow (YM). DECT-derived marrow fat fraction was validated using histology of lumbar vertebrae obtained from cadavers. The fractions of RM (RMF = RM/total marrow) and YMF were calculated in each skeletal region to assess the correlation of marrow composition with sites and ages. Treatment planning was simulated to target irradiation differentially at a higher dose (18 Gy) to either RM or YM and a lower dose (12 Gy) to the rest of the skeleton. Results: A significant correlation between fat fractions obtained from DECT and cadaver histology samples was observed (r=0.861, P<.0001, Pearson). The RMF decreased in the head, neck, and chest was significantly inversely correlated with age but did not show any significant age-related changes in the abdomen and pelvis regions. Conformity of radiation to targets (RM, YM) was significantly dependent on skeletal sites. The radiation exposure was significantly reduced (P<.05, t test) to organs at risk (OARs) in RM and YM irradiation compared with standard total marrow irradiation (TMI). Conclusions: Whole-body DECT offers a new imaging technique to visualize and measure skeletal-wide marrow composition. The DECT-based treatment planning offers volumetric and site-specific precise radiation dosimetry of RM and YM, which varies with aging. Our proposed method could be used as a functional compartment of TMI for further targeted radiation to specific bone marrow environment, dose escalation, reduction of doses to OARs, or a combination of these factors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Micro- and nano-scale hollow TiO{sub 2} fibers by coaxial electrospinning: Preparation and gas sensing

We report the preparation of micro- and nano-scale hollow TiO{sub 2} fibers using a coaxial electrospinning technique and their gas sensing properties in terms of CO. The diameter of hollow TiO{sub 2} fibers can be controlled from 200 nm to several micrometers by changing the viscosity of electrospinning solutions. Lower viscosities produce slim hollow nanofibers. In contrast, fat hollow microfibers are obtained in the case of higher viscosities. A simple mathematical expression is presented to predict the change in diameter of hollow TiO{sub 2} fibers as a function of viscosity. The successful control over the diameter of hollow TiO{sub 2} fibers is expected to bring extensive applications. To test a potential use of hollow TiO{sub 2} fibers in chemical gas sensors, their sensing properties to CO are investigated at room temperature. - Graphical abstract: Microstructures of as-prepared and calcined hollow TiO{sub 2} fibers prepared by the electrospinning technique with a coaxial needle. Dynamic response at various CO concentrations for the sensor fabricated with the hollow TiO{sub 2} fibers. Highlights: > Hollow TiO{sub 2} fibers were synthesized using a coaxial electrospinning technique. > Their diameter can be controlled by changing the viscosity of electrospinning solutions. > Lower viscosities produce slim hollow nanofibers. > In contrast, fat hollow microfibers are obtained in the case of higher viscosities. > Successful control over the diameter of hollow TiO{sub 2} fibers will bring extensive applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Stable expression of lipocalin-type prostaglandin D synthase in cultured preadipocytes impairs adipogenesis program independently of endogenous prostanoids

Lipocalin-type prostaglandin D synthase (L-PGDS) expressed preferentially in adipocytes is responsible for the synthesis of PGD{sub 2} and its non-enzymatic dehydration products, PGJ{sub 2} series, serving as pro-adipogenic factors. However, the role of L-PGDS in the regulation of adipogenesis is complex because of the occurrence of several derivatives from PGD{sub 2} and their distinct receptor subtypes as well as other functions such as a transporter of lipophilic molecules. To manipulate the expression levels of L-PGDS in cultured adipocytes, cultured preadipogenic 3T3-L1 cells were transfected stably with a mammalian expression vector having cDNA encoding murine L-PGDS oriented in the sense direction. The isolated cloned stable transfectants with L-PGDS expressed higher levels of the transcript and protein levels of L-PGDS, and synthesized PGD{sub 2} from exogenous arachidonic acid at significantly higher levels. By contrast, the synthesis of PGE{sub 2} remained unchanged, indicating no influence on the reactions of cyclooxygenase (COX) and PGE synthase. Furthermore, the ability of those transfectants to synthesize {Delta}{sup 12}-PGJ{sub 2} increased more greatly during the maturation phase. The sustained expression of L-PGDS in cultured stable transfectants hampered the storage of fats during the maturation phase of adipocytes, which was accompanied by the reduced gene expression of adipocyte-specific markers reflecting the down-regulation of the adipogenesis program. The suppressed adipogenesis was not rescued by either exogenous aspirin or peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonists including troglitazone and {Delta}{sup 12}-PGJ{sub 2}. Taken together, the results indicate the negative regulation of the adipogenesis program by the enhanced expression of L-PGDS through a cellular mechanism involving the interference of the PPAR{gamma} signaling pathway without the contribution of endogenous pro-adipogenic prostanoids. -- Highlights: Black-Right-Pointing-Pointer Cultured preadipocytes were transfected with sense lipocalin-type PGD synthase. Black-Right-Pointing-Pointer The cloned transfectants had a higher ability to synthesize PGD{sub 2} and PGJ{sub 2} series. Black-Right-Pointing-Pointer The sustained expression of sense L-PGDS hampered the storage of fats. Black-Right-Pointing-Pointer Adipogenesis program was suppressed independently of endogenous prostanoids.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Pancreatic stellate cell activation is regulated by fatty acids and ER stress

Introduction: Pancreatic pathologies are characterized by a progressive fibrosis process. Pancreatic stellate cells (PSC) play a crucial role in pancreatic fibrogenesis. Endoplasmic reticulum (ER) stress emerges as an important determinant of fibrotic remodeling. Overload of fatty acids (FA), typical to obesity, may lead to lipotoxic state and cellular stress. Aim: To study the effect of different lipolytic challenges on pancreatic ER stress and PSC activation. Methods: Primary PSCs were exposed to different FAs, palmitate (pal) and oleate (ole), at pathophysiological concentrations typical to obese state, and in acute caerulein-induced stress (cer). PSC activation and differentiation were analyzed by measuring fat accumulation (oil-red staining and quantitation), proliferation (cells count) and migration (wound- healing assay). PSC differentiation markers (α-sma, fibronectin, tgf-β and collagen secretion), ER stress unfolded protein response and immune indicators (Xbp1, CHOP, TNF-α, IL-6) were analyzed at the transcript and protein expression levels (quantitative RT-PCR and western blotting). Results: PSC exposure to pal and ole FAs (500 µM) increased significantly fat accumulation. Proliferation and migration analysis demonstrated that ole FA retained PSC activation, while exposure to pal FA significantly halted proliferation rate and delayed migration. Cer significantly augmented PSC differentiation markers α- sma, fibronectin and collagen, and ER stress and inflammation markers including Xbp1, CHOP, TNF-α and IL-6. The ole FA treatment significantly elevated PSC differentiation markers α-sma, fibronectin and collagen secretion. PSC ER stress was demonstrated following pal treatment with significant elevation of Xbp1 splicing and CHOP levels. Conclusion: Exposure to pal FA halted PSC activation and differentiation and elevated ER stress markers, while cer and ole exposure significantly induced activation, differentiation and fibrosis. Thus, dietary FA composition should be considered and optimized to regulate PSC activation and differentiation in pancreatic pathologies. - Highlights: • Pancreatic stellate cells (PSC) play a crucial role in pancreatic fibrogenesis. • Endoplasmic reticulum (ER) stress is an important determinant of fibrotic remodeling. • Overload of fatty acids, typical to obesity, may lead to lipotoxicity and cellular stress. • Exposure to pal FA halts PSC activation, differentiation and elevated ER stress. • Cer and ole exposure significantly induced activation, differentiation and fibrosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Silencing of RSPO1 mitigates obesity-related renal fibrosis in mice by deactivating Wnt/β-catenin pathway

Highlights: • Renal RSPO1 expression was increased in mice fed on high-fat diet for 12 weeks. • Silencing RSPO1 remitted kidney dysfunction and renal fibrosis in obesity mice. • Silencing RSPO1 inhibited LGR4 expression and Wnt/β-catenin pathway activation. • RSPO1/LGR4 axis was involved in obesity-related renal fibrosis. Obesity, a global epidemic, is one of the critical causes of chronic kidney disease (CKD). R-spondin1 (RSPO1) possessing the potential to activate Wnt/β-catenin pathway was reported to be elevated in circulation of obesity objects. However, the function of RSPO1 and the latent mechanism in obesity-related CKD are still left to be revealed. In the present study, renal RSPO1 expression was increased in mice fed on high-fat diet (HFD) for 12 weeks. Lentivirus-mediated RSPO1 knockdown partly recovered obesity-related metabolic symptoms, while distinctly remitted kidney dysfunction and renal fibrosis in obesity mice. In vitro, recombinant RSPO1 was found to elevate leucine-rich repeat-containing G protein coupled receptor 4 (LGR4) expression, promote Wnt/β-catenin signaling pathway activation, facilitate epithelial-mesenchymal transition (EMT) and increase collagen deposition in HK2 renal tubular cells. Such pro-fibrotic effect of RSPO1 was diminished by LGR4 siRNA in HK2 cells. In summary, we demonstrate that RSPO1/LGR4 axis is involved in obesity-related renal fibrosis at least through activating Wnt/β-catenin signaling pathway, providing a potential therapeutic target for this disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Microbiome characterization by high-throughput transfer RNA sequencing and modification analysis

Advances in high-throughput sequencing have facilitated remarkable insights into the diversity and functioning of naturally occurring microbes; however, current sequencing strategies are insufficient to reveal physiological states of microbial communities associated with protein translation dynamics. Transfer RNAs (tRNAs) are core components of protein synthesis machinery, present in all living cells, and are phylogenetically tractable, which make them ideal targets to gain physiological insights into environmental microbes. Here we report a direct sequencing approach, tRNA-seq, and a software suite, tRNA-seq-tools, to recover sequences, abundance profiles, and post-transcriptional modifications of microbial tRNA transcripts. Our analysis of cecal samples using tRNA-seq distinguishes high-fat-and low-fat-fed mice in a comparable fashion to 16S ribosomal RNA gene amplicons, and reveals taxon- and diet-dependent variations in tRNA modifications. Our results provide taxon-specific in situ insights into the dynamics of tRNA gene expression and post-transcriptional modifications within complex environmental microbiomes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Ligand dependent interaction between PC-TP and PPARδ mitigates diet-induced hepatic steatosis in male mice

Phosphatidylcholine transfer protein (PC-TP; synonym StarD2) is a soluble lipid-binding protein that transports phosphatidylcholine (PC) between cellular membranes. To better understand the protective metabolic effects associated with hepatic PC-TP, we generated a hepatocyte-specific PC-TP knockdown (L-Pctp -/- ) in male mice, which gains less weight and accumulates less liver fat compared to wild-type mice when challenged with a high-fat diet. Hepatic deletion of PC-TP also reduced adipose tissue mass and decreases levels of triglycerides and phospholipids in skeletal muscle, liver and plasma. Gene expression analysis suggest that the observed metabolic changes are related to transcriptional activity of peroxisome proliferative activating receptor (PPAR) family members. An in-cell protein complementation screen between lipid transfer proteins and PPARs uncovered a direct interaction between PC-TP and PPARδ that was not observed for other PPARs. We confirmed the PC-TP– PPARδ interaction in Huh7 hepatocytes, where it was found to repress PPARδ-mediated transactivation. Mutations of PC-TP residues implicated in PC binding and transfer reduce the PC-TP-PPARδ interaction and relieve PC-TP-mediated PPARδ repression. Reduction of exogenously supplied methionine and choline reduces the interaction while serum starvation enhances the interaction in cultured hepatocytes. Together our data points to a ligand sensitive PC-TP– PPARδ interaction that suppresses PPAR activity.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Extraction and characterization of elastin from poultry skin

Poultry by-products have a great economic potential that need to be exploited. Poultry skin could be utilized to produce elastin, which is often incorporated in the production of functional food or medicine due to its antioxidative properties. This study was conducted to determine the physicochemical and microstructural characteristics of elastins isolated from broiler and spent hen skin. Analyses including proximate and amino acid composition along with transmission electron microscopy (TEM) were carried out. In this study, elastin was successfully extracted from broiler and spent hen skin using three successive solvents extract of NaCl, acetone and NaOH respectively. It was apparent that the fat content of extracted elastin from broiler skin was higher (P < 0.05) than spent hen’s, with both samples recording less than 1% fat. Moreover, broiler skin elastin also had a higher protein content (68.3%) than spent hen’s (67.8%). Both skin sources contained glycine as the major amino acid (19–20%), followed by glutamic acid, proline, alanine and arginine. The results of TEM indicated that the use of collagenase enzyme or further purification efforts should be incorporated along with the extraction methods used because of the presence of collagen and other debris in the resultant elastin.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Metabolite Regulation of Nuclear Localization of Carbohydrate-response Element-binding Protein (ChREBP): Role of AMP as an Allosteric Inhibitor

The carbohydrate-response element-binding protein (ChREBP) is a glucose-responsive transcription factor that plays an essential role in converting excess carbohydrate to fat storage in the liver. In response to glucose levels, ChREBP is regulated by nuclear/cytosol trafficking via interaction with 14-3-3 proteins, CRM-1 (exportin-1 or XPO-1), or importins. Nuclear localization of ChREBP was rapidly inhibited when incubated in branched-chain α-ketoacids, saturated and unsaturated fatty acids, or 5-aminoimidazole-4-carboxamide ribonucleotide. Here, we discovered that protein-free extracts of high fat-fed livers contained, in addition to ketone bodies, a new metabolite, identified as AMP, which specifically activates the interaction between ChREBP and 14-3-3. The crystal structure showed that AMP binds directly to the N terminus of ChREBP-α2 helix. Our results suggest that AMP inhibits the nuclear localization of ChREBP through an allosteric activation of ChREBP/14-3-3 interactions and not by activation of AMPK. As a result, AMP and ketone bodies together can therefore inhibit lipogenesis by restricting localization of ChREBP to the cytoplasm during periods of ketosis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗