bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intestinal Epithelial TCPTP Deficiency Reduces Expression of the Tight Junction Protein Tricellulin through MEK/ERK Signaling
Authors: Krishnan Moorthy , Chan Alvin Lee , Wong Brandon Matthew , Sayoc Anica , McCole Declan F. 
Published: November 2023

Genome‐wide association studies identified protein tyrosine phosphatase non‐receptor type‐2 (PTPN2) as a susceptibility gene for inflammatory bowel disease (IBD), Diabetes and Celiac disease, while loss of the PTPN2 protein product T‐cell protein tyrosine phosphatase (TCPTP) compromises intestinal epithelial barrier function. The protein composition of tight junctions (TJ) determines the tightness of the barrier and alterations in select TJ proteins leads to increased paracellular permeability. Tricellulin (also called marvelD2) is a recently discovered tight junction (TJ) protein, which is preferentially localized at tricellular contacts. Tricellulin plays an important role in the maintenance of intestinal epithelial barrier function by restricting paracellular permeability to macromolecules. The aim of the present study was to identify the molecular mechanism underlying barrier defects in TCPTP‐deficient intestinal epithelial cells (IEC). For this purpose, we developed Caco2‐BBe and HT‐29 intestinal epithelial cell lines (IECs) expressing short hairpin RNA for TCPTP using a lentiviral system to stably knock down TCPTP expression (TCPTP‐KD). Western blot analysis indicated that TCPTP expression was significantly reduced (by 45 ± 4%, p<0.01, n=3) in TCPTP‐KD cells. FD4 permeability was increased in KD cells (p<0.001; n=3) compared to control cells. Western blot and immunofluorescence studies revealed that the expression of tricellulin expression was decreased (WB: 44 ± 8.8%, p<0.05; n=3) in unchallenged TCPTP‐KD cells compared to control shRNA transfected cells. This decrease was further enhanced by challenge with the pro‐inflammatory cytokine interferon‐gamma (IFN‐g) (n=2). In previous studies, we observed increased basal phosphorylation of the TCPTP substrate ERK1/2 in TCPTP‐KD cells. Moreover, an inverse relationship exists between mitogen‐activated protein kinase kinase kinase 1 (MEKK1) that lies upstream of ERK1/2, and MarvelD3, a member of the same protein family as tricellulin. To investigate whether tricellulin loss in TCPTP‐KD cells occurs through MEK/ERK signaling, TCPTP‐KD IEC were treated with the ERK1/2 inhibitor U0126 (10mM) for 14 hours. ERK inhibition rescued tricellulin expression in TCPTP‐KD cells. In conclusion, we report that tricellulin expression is down regulated, at least in part, by the MEK/ERK pathway and that decreased tricellulin levels could contribute to the increased macromolecule permeability in cells lacking TCPTP.Support or Funding InformationNIH‐R01‐DK‐091281 and Crohn's & Colitis Foundation of America(CCFA) to Declan F. McCole
Dietary Kynurenine, the oxidized metabolite of tryptophan, suppresses osteoprogenitor expression of Hdac3 resulting in increased marrow adiposity and age‐related bone loss
Authors: McGee‐Lawrence Meghan , Pierce Jessica , Yu Kanglun , Davis Colleen , Dukes Amy , Zhong Qing , Xu Jianrui , Bollag Wendy , Elsalanty Mohammed , Kennedy Eileen , Ding Kehong , Hill William , Hamrick Mark W , Isales Carlos 
Published: November 2023

BackgroundAging results in loss of skeletal bone mass resulting in osteoporosis and increased marrow fat although the mechanism remains poorly understood. Our previous studies support Hdac3 as a regulator of this process, as osteoprogenitor Hdac3 expression is decreased in aged vs. young mice, and decreased expression of Hdac3 causes an osteopenic, high marrow fat phenotype with increased lipid storage in osteoprogenitors. However, causative factors for decreased Hdac3 expression with aging are unknown. Our group has shown that aromatic amino acids (tyrosine, phenylalanine, tryptophan) function as antioxidants with a protective role in bone, whereas their oxidized byproducts antagonize this effect and promote bone loss. Circulating levels of kynurenine, the oxidized product of tryptophan, are increased in aged (24mo) vs. mature (12mo) mice, and we recently observed that kynurenine‐treated mice have high marrow fat and low bone mass, mimicking the phenotype of Hdac3‐deficient and aged animals. This raises the possibility that oxidized by products, in particular kynurenine, could be a mechanistic link between aging and bone loss.ObjectiveWe explored intersecting roles of kynurenine and osteoprogenitor Hdac3 in marrow adiposity and osteoprogenitor lipid storage.Methods and ResultsMature (12 months) male C57BL6 mice were fed 18% protein (normal diet), 8% protein+50μM kynurenine or 8% protein+100μM kynurenine for 8 weeks. We also injected young male CD‐1 mice with kynurenine (2 or 20 mg/day) for 10 days to study kynurenine's acute effects. Kynurenine caused bone loss through increased osteoclast activity and decreased osteoblast activity. Bone marrow adiposity was dose‐dependently increased in kynurenine‐fed mice, and osteogenic BMSC cultures from kynurenine‐treated mice showed decreased expression of Hdac3 and co‐factor NCoR1, increased expression of lipid storage genes Cidec and Plin1, and no changes in expression of Pparγ2 or Fasn. These results mimic expression patterns in osteoprogenitors from Hdac3‐insufficient and aged mice.ConclusionAging‐induced increases in kynurenine may suppress Hdac3 which impairs osteoblast function and increases marrow fat with age.
Diacylglycerol and Phosphatidic: Regulation of Levels and Roles in Synaptic Vesicle Cycling
Authors: Goldschmidt Hana , Barber Casey , Huganir Richard , Raben Daniel 
Published: November 2023

Recognition that lipids and lipid metabolism play critical structural and regulatory roles in the central nervous system (CNS) is increasing. The phosphoinositides (PtdIns) have received the most attention but two related lipids, diacylglycerol (DAG) and phosphatidic acid (PtdOH) are also believed to play key roles in neurotransmission. In contrast to inositol lipid metabolism, the enzymes involved in modulating the levels of these lipids, and their regulation are not well studied. Recently we reported evidence demonstrating a role for diacylglycerol kinase‐θ (DGK‐θ) in modulating evoked endocytosis in the in synaptic vesicle cycling in mammalian central nervous system neurons. This enzyme reduces DAG while elevating PtdOH by catalyzing the ATP‐dependent phosphorylation of DAG to PtdOH. Another class of enzymes involved in generating PtdOH in signaling pathways are phospholipases D (PLDs). These enzymes generate PdOH by catalyzing the hydrolysis of phosphatidylcholine (PtdCho) leading to the generation of PtdOH. This PtdOH may in turn be de‐phosphorylated to DAG. Both DGK‐θ and a PLD (PLD1) have been implicated in neurotransmitter release. We have presented some data implicating DGK‐θ in modulating endocytosis during synaptic vesicle cycling. The role of PLD1 in this cycle is less clear. We have been studying the role of both enzymes, and their regulation, in synaptic vesicle cycling and given some attention to the potential involvement of these enzymes in neurons that depend on rapid and repetitive neurotransmitter release as seen in ribbon synapses.Support or Funding InformationNIH R01NS077923
A Fluorogenic Proteostasis Sensor to Monitor Proteome Stress in Real‐Time
Authors: Zhang Xin , Liu Yu 
Published: November 2023

Cellular stress can lead to global misfolding and aggregation of the endogenous proteome, resulting in a disruption of protein homeostasis (proteostasis). Monitoring proteostasis efficacy in response to stress in real time remains one of the major technical challenges facing established sensors of this process. Herein we introduce a fluorogenic proteostasis sensor based on a metastable Halo mutant in which misfolding and aggregation visually reports proteostasis deficiency. For this purpose, a solvatochromic fluorophore was designed to act as a ligand that can form a stable conjugate with Halo. The Halo•ligand conjugate maintains a fluorescent dark state when the Halo protein is folded but fluoresces strongly when the Halo•ligand conjugate misfolds and aggregates. In both E. coli and mammalian cells, we have demonstrated the utility of the sensor in monitoring proteostasis deficiency under a variety of stress conditions including environmental perturbations and incubation with a proteasome inhibitor. We show that the fluorogenic properties of this proteostasis sensor enables facile monitoring the proteome stress and allows us to discover the proteome aggregation that is induced by a series of anti‐cancer drugs. This work highlights the utility of solvatochromic fluorophores in direct visualization of protein misfolding and aggregation in live cells, providing new methodologies for real‐time analyses of cellular proteostasis upon exposure to different types of stress conditions.Support or Funding InformationThis work has been supported by the Burroughs Wellcome Fund Career Award at the Scientific Interface, the Paul Berg Early Career Professorship, and the Lloyd and Dottie Huck Early Career Award.
Imaging developmentally‐regulated secretory granule biogenesis and exocytosis
Authors: Hagen Kelly Ten , Tran Duy T , Ji Suena 
Published: November 2023

Regulated secretion is an essential process by which cells deliver molecules to the cell surface and extracellular space in response to an external signal. We have established a system to directly visualize the secretion of high molecular weight cargo such as mucins in vivo, to define the critical factors at each step in this process. Using Drosophila salivary glands expressing fluorescently‐labeled secretory cargo (Sgs3‐GFP), myosin II (Zipper‐GFP), actin binding protein (Lifeact‐Ruby) or a PIP2 reporter (PLC□PH‐EGFP), we are able to visualize the spatial and temporal dynamics of regulated secretion. Through 4D‐imaging of secreting glands, we show that actin is cleared at the site of vesicle fusion and re‐assembled directionally around secreting granules. Moreover, we demonstrate that fusion pore formation and PIP2 redistribution precede actin and myosin recruitment to fused granules. Additionally, we show a crucial role for the branched actin nucleators Arp2, Arp3 and their nucleation promoting factor WASp in cargo expulsion and integration of the granular membrane with the apical plasma membrane. By combining in vivo and ex vivo imaging of fluorescently‐labeled molecules with the power of Drosophila genetics, we have developed a tractable experimental system for studying the factors that regulate hormone‐induced secretion during development. Ongoing experiments focus on investigating the role of O‐glycosylation in secretory granule biogenesis, morphology and secretion.Support or Funding InformationThis work was supported by the Intramural Research Program of the NIDCR, National Institutes of Health (Z01‐DE‐000713 to K.G.T.H.).
Bacterial fermentation end‐products are related to hepatic steatosis among overweight and obese adults
Authors: Thompson Sharon V. , Berndt Jake W. , Edwards Caitlyn G. , Erdman John W. , Khan Naiman A. , O'Brien William D. , Holscher Hannah D. 
Published: November 2023

BackgroundNonalcoholic fatty liver disease (NAFLD) is an increasingly prevalent manifestation of metabolic dysfunction characterized by elevated hepatic fat accumulation and elevated liver enzymes. Currently it is estimated that NAFLD may affect up to half of the US population. Although previous work has linked excess adiposity with NAFLD, there is a paucity of data examining whether hepatic steatosis is also related to gut microbiota fermentation end‐products, particularly among humans. Discovering this knowledge stands to benefit future dietary approaches to preventing the development of NAFLD in the increasingly overweight and obese US population.MethodsAccordingly, this study aimed to characterize the relationships between hepatic steatosis and markers of liver function, fat mass, and gut microbiota fermentation end‐products. We conducted correlational analyses concerning adiposity (%Fat), volatile fatty acid (VFA) concentrations, and measures of hepatic health within a sample of overweight/obese (BMI ≥ 27.5 kg/m2) adults (N=57, 64.9% females). Whole body and total, visceral, and subcutaneous abdominal adiposity (% Fat Mass) were measured using DXA. Gas chromatography mass spectroscopy was used to assess VFA concentrations, including short‐chain fatty acids (SCFAs; acetate, propionate, butyrate) and branched‐chain fatty acids (BCFAs; isovalerate, valerate, and isobutryate). Hepatic enzyme concentrations (whole blood) were assessed using an automated chemical analyzer. Hepatic steatosis (fat fraction [FF]) was measured using quantitative ultrasound in a subset of participants (n=21). Initial bivariate correlations were conducted to examine relationships between hepatic health measures, adiposity, and bacterial fermentation end products. Subsequently, a partial correlation was conducted to determine whether the relationships between bacterial fermentation end‐products and hepatic measures persisted following the adjustment of adiposity.ResultsElevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), and hepatic FF were present in 16.7%, 13.0%, and 5.1% of participants, respectively. Whole body %Fat was negatively correlated with butyrate concentrations (r=−0.29, p=0.03, n=57). Hepatic FF was positively related to isovalerate (r=0.48, p=0.03, n=21) and tended to correlate with isobutyrate (r=0.40, p=0.07, n=21). Partial correlational analyses revealed that the relationships between hepatic FF and BCFA concentrations may be mediated by BMI and whole body, visceral, and subcutaneous adiposity.ConclusionsResults of the present study indicate that VFA concentrations differ by hepatic health and adiposity status. Further research is needed to determine if these observed relationships are mediated by dietary factors or gastrointestinal microbial abundances.
Correlations of Abdominal Fat and Colonic Sulfidogenic Bacteria in African Americans and Non‐Hispanic Whites with Newly Diagnosed Colorectal Cancer
Authors: Gomez‐Perez Sandra L , Yazici Cemal , Wolf Patricia M , Braunschweig Carol , Xicola Rosa , Llor Xavier , Ellis Nathan , Tussing‐Humphreys Lisa , Mutlu Ece A , Gaskins Rex H 
Published: November 2023

ObjectiveTo determine correlations between abdominal fat distribution (AFD) and abundance of gut microbiota bacterial gene targets in African Americans (AAs) and Non‐Hispanic Whites (NHWs) with incident CRC.MethodsAdults (n=64; AAs=44, NHWs=20) with incident colorectal cancer with a preoperative abdominal computed tomography scan and non‐involved colonic tissue for assessment of gene targets of sulfate‐reducing bacteria [SRB] in the colonic mucosa were included. A cross‐sectional CT slice at mid‐point of L3 vertebra was analyzed for waist circumference (cm) and surface areas (cm2) of abdominal fat: total (TAT), subcutaneous (SAT), superficial subcutaneous (SSAT), deep subcutaneous (DSAT), and visceral (VAT) adipose tissues. Quantitative PCR was used to measure abundance of SRB gene targets in non‐involved colonic mucosa including: pan‐dissimulatory sulfate reductase A (DSR1F4r), Desulfovibrio (DSV), Desulfobacter (DSB), and Desulfotomaculum (DFM). Pearson correlation stratified by race was used to assess relationships between abdominal fat and gut microbiota.ResultsMean age (SD), BMI (SD) and waist circumference (SD) for AA vs. NHW were: 63.4(8.9) vs. 60.2(6.7), 27(5.6) vs 29.2(6.1) and 97.6(11.4) vs 103.9(15.6), respectively. About 60% (27/44) of AAs and 85% (17/20) of NHWs were male. Significant correlations were observed between the abundance gene targets of sulfidogenic bacteria, DSV, DSB, and DFM with cross‐sectional (cm2) levels of SSAT and DSAT. SSAT was negatively associated with the abundance of DSB (r=−0.4985, p=0.0027, n=34) whereas DSAT was negatively associated with abundance of DSV (r=−0.3469, p=0.0262, n=41) and DFM (R=−0.3099, p=0.0486, n=41) in AAs only. No associations for bacterial gene targets and AFD were observed for NHWs.ConclusionsThese findings suggest that AFD may be related to sulfidogenic bacterial species in colonic mucosa differentially in AAs compared to NHWs.Support or Funding InformationFunding: The project described was supported by grant numbers 5R25‐CA057699 and 1R01‐CA204808 from the National Cancer Institute and its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute.
Effects of a 6‐Month Lifestyle Intervention on Dietary Intake and Blood Pressure in Hemodialysis Patients
Authors: Chan Lauren E. , Perez Luis , Burrows Brett , Biruete Annabel , Barnes Jennifer L , Wilund Kenneth R 
Published: November 2023

Previous studies have demonstrated a positive correlation between dietary sodium intake and blood pressure (BP) in hemodialysis (HD) patients. High BP is linked to increased cardiovascular (CV) mortality, and CV disease contributes to 41% of deaths among HD patients. To reduce these risks, HD patients are often counseled to restrict their dietary sodium intake, but few studies have examined the efficacy of this strategy.In this study, we aimed to assess the impacts of individualized low sodium dietary counseling in conjunction with a liberalized diet approach on sodium intake and BP. Liberalized dietary guidelines include more whole food consumption, decreasing foods eaten outside the home, and increased food label reading.32 patients (age = 53.8 ± 13.5y, 44% female) enrolled in the study and underwent baseline testing, including three 24‐hour recalls, and standardized BP measurement. Dietary recalls were analyzed using the Nutrition Data System for Research. During the 6‐month intervention, participants received weekly one‐on‐one dietary counseling to reduce sodium intake, address a liberalized diet, and set individual goals. Study coordinators performed counseling, supervised by both research and clinical dietitians. Baseline testing measures were repeated at the end of the 6‐month intervention period.Comparing baseline (BL) measurements to those post‐intervention (6m), average kilocalorie (kcal) intake was not significantly different (BL 1489 ± 968 vs. 6m 1445 ± 484 kcal, p= 0.876). Daily protein intake did not change over 6 months (BL 55.16 ± 21.62 vs. 6m 59.63 ± 21.15 grams, p=0.605). Total sodium intake numerically decreased (BL 2780.4 ± 1112.6 vs 6m 2482.5 ± 1147.6 mg, p=0.297), as did milligrams of sodium normalized per kcal (BL 2.07 ± 0.87 vs 1.68 ± 0.54 mg/kcal, p=0.08). Systolic BP (BL 154.71 ± 26.89 vs. 6m 157.57 ± 25.07 mmHg, p=0.674) and diastolic BP (BL 77.78 ± 20.54 vs 6m 77.85 ± 16.17 mmHg, p= 0.991) showed no significant changes, but total number of BP medications prescribed to patients (BL 2.93 ± 1.26 vs 6m 1.5 ± 1.09 medications) were significantly reduced (p=0.004).Maintenance of energy and protein intake is important for HD patients to preserve their lean mass and serum protein values, a potential challenge during sodium restrictions. Notably, this six‐month dietary intervention was not associated with decreases in kcal and protein intake, although patients remain below recommendations. Though not statistically significant, the modestly reduced sodium intake that was found may suggest developing changes in consumption due to our intervention. Minimal changes in sodium intake had no significant effects on systolic and diastolic BP values, but may have played a role in the significant decrease in number of BP medications. This indicates that a six‐month dietary intervention may be meaningful for both systolic and diastolic BP maintenance with decreased BP medication usage.
Markers of Renal Function are Unchanged in Obese Older Adults Consuming a Higher Protein, Hypocaloric Diet for 6 Months
Authors: Starr Kathryn N Porter , McDonald Shelley R , Orenduff Melissa C , Jarman Aubrey K , Sloane Richard , Pieper Carl F , Bales Connie W 
Published: November 2023

Higher intakes of dietary protein (i.e., exceeding the RDA of 0.8 g/kg body weight/day) are being widely advocated for older adults with the intent of mitigating age‐related loss of muscle mass and strength. However, these recommendations are accompanied by concerns about the potential impact on renal function, especially because kidney function declines with age in many individuals. Yet, there is a lack of evidence on the topic, especially in older adults, leading to ambiguity in the clinical setting about the pros and cons of higher protein diets for high‐risk elders whose function is threatened by sarcopenia or sarcopenic obesity. We analyzed blood indicators of renal function collected in our recent trial of higher protein, hypocaloric (500 kcal deficit) diets for obese (mean BMI= 37.7±6.5 kg/m2), functionally frail (by Short Physical Performance Battery) older (mean age = 68.4±5.3 yr) adults (n=40) with age‐normal renal status (estimated glomerular filtration rate [eGFR] ≥ 45 mL/min/1.73m2) to examine the protein effect during a period of challenge to muscle mass (negative energy balance). Control participants were prescribed 0.8 g protein/kg body weight (bw) and Protein participants 1.2 g protein/kg bw distributed as 30+ grams of lean, high‐quality protein three times a day. The Protein group significantly increased dietary protein intake (3‐day diet record) to 1.12 g/kg/bw, while the Control group maintained a protein intake of 0.90 g/kg/bw; both groups had significantly (P<0.0001) decreased their bw at 6 months (Protein = −7.7±6.0%, Control = −5.7±5.4%). Blood indicators of renal function (eGFR and blood urea nitrogen [BUN]) were assessed at baseline and 6 months. At 6 months, both GFR (Control = 79.7±15.5 and Protein = 77.1±16.6 mL/min/1.73m2, P=0.17) and BUN (Control = 17.1±4.8 and Protein = 18.8±5.1 mg/dL, P=0.56) remained unchanged. While additional studies with subject larger numbers are needed, our finding that renal function was not impaired by the higher protein weight loss intervention has important implications for treatment of sarcopenic obesity and aligns with recent recommendations that older adults consume generous amounts of protein at each meal.Support or Funding InformationThis study was funding by the Beef Checkoff Program and received additional support from the National Institutes of Health (5T32 AG000029; 1P30 AG028716) and the VA Advanced Fellowship Program, GRECC.