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Manganese Detoxification by MntE Is Critical for Resistance to Oxidative Stress and Virulence of .
Grunenwald CM, Choby JE, Juttukonda LJ, Beavers WN, Weiss A, Torres VJ, Skaar EP
(2019) MBio 10:
MeSH Terms: Animals, Cation Transport Proteins, Disease Models, Animal, Gene Expression Regulation, Bacterial, Homeostasis, Iron, Manganese, Mice, Inbred BALB C, Microbial Viability, Oxidative Stress, Staphylococcal Infections, Staphylococcus aureus, Transcription Factors, Transcription, Genetic, Virulence
Show Abstract · Added April 2, 2019
Manganese (Mn) is an essential micronutrient critical for the pathogenesis of , a significant cause of human morbidity and mortality. Paradoxically, excess Mn is toxic; therefore, maintenance of intracellular Mn homeostasis is required for survival. Here we describe a Mn exporter in , MntE, which is a member of the cation diffusion facilitator (CDF) protein family and conserved among Gram-positive pathogens. Upregulation of transcription in response to excess Mn is dependent on the presence of MntR, a transcriptional repressor of the Mn uptake system. Inactivation of or leads to reduced growth in media supplemented with Mn, demonstrating MntE is required for detoxification of excess Mn. Inactivation of results in elevated levels of intracellular Mn, but reduced intracellular iron (Fe) levels, supporting the hypothesis that MntE functions as a Mn efflux pump and Mn efflux influences Fe homeostasis. Strains inactivated for are more sensitive to the oxidants NaOCl and paraquat, indicating Mn homeostasis is critical for resisting oxidative stress. Furthermore, and are required for full virulence of during infection, suggesting experiences Mn toxicity Combined, these data support a model in which MntR controls Mn homeostasis by balancing transcriptional repression of and induction of , both of which are critical for pathogenesis. Thus, Mn efflux contributes to bacterial survival and virulence during infection, establishing MntE as a potential antimicrobial target and expanding our understanding of Mn homeostasis. Manganese (Mn) is generally viewed as a critical nutrient that is beneficial to pathogenic bacteria due to its function as an enzymatic cofactor and its capability of acting as an antioxidant; yet paradoxically, high concentrations of this transition metal can be toxic. In this work, we demonstrate utilizes the cation diffusion facilitator (CDF) family protein MntE to alleviate Mn toxicity through efflux of excess Mn. Inactivation of leads to a significant reduction in resistance to oxidative stress and mediated mortality within a mouse model of systemic infection. These results highlight the importance of MntE-mediated Mn detoxification in intracellular Mn homeostasis, resistance to oxidative stress, and virulence. Therefore, this establishes MntE as a potential target for development of anti- therapeutics.
Copyright © 2019 Grunenwald et al.
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15 MeSH Terms
Neurog3-Independent Methylation Is the Earliest Detectable Mark Distinguishing Pancreatic Progenitor Identity.
Liu J, Banerjee A, Herring CA, Attalla J, Hu R, Xu Y, Shao Q, Simmons AJ, Dadi PK, Wang S, Jacobson DA, Liu B, Hodges E, Lau KS, Gu G
(2019) Dev Cell 48: 49-63.e7
MeSH Terms: Animals, Basic Helix-Loop-Helix Transcription Factors, Cell Differentiation, Cell Lineage, Endocrine Cells, Homeodomain Proteins, Insulin-Secreting Cells, Islets of Langerhans, Mice, Nerve Tissue Proteins, Organogenesis, Pancreas, Transcription Factors
Show Abstract · Added February 6, 2019
In the developing pancreas, transient Neurog3-expressing progenitors give rise to four major islet cell types: α, β, δ, and γ; when and how the Neurog3 cells choose cell fate is unknown. Using single-cell RNA-seq, trajectory analysis, and combinatorial lineage tracing, we showed here that the Neurog3 cells co-expressing Myt1 (i.e., Myt1Neurog3) were biased toward β cell fate, while those not simultaneously expressing Myt1 (Myt1Neurog3) favored α fate. Myt1 manipulation only marginally affected α versus β cell specification, suggesting Myt1 as a marker but not determinant for islet-cell-type specification. The Myt1Neurog3 cells displayed higher Dnmt1 expression and enhancer methylation at Arx, an α-fate-promoting gene. Inhibiting Dnmts in pancreatic progenitors promoted α cell specification, while Dnmt1 overexpression or Arx enhancer hypermethylation favored β cell production. Moreover, the pancreatic progenitors contained distinct Arx enhancer methylation states without transcriptionally definable sub-populations, a phenotype independent of Neurog3 activity. These data suggest that Neurog3-independent methylation on fate-determining gene enhancers specifies distinct endocrine-cell programs.
Published by Elsevier Inc.
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Examining How the MAFB Transcription Factor Affects Islet β-Cell Function Postnatally.
Cyphert HA, Walker EM, Hang Y, Dhawan S, Haliyur R, Bonatakis L, Avrahami D, Brissova M, Kaestner KH, Bhushan A, Powers AC, Stein R
(2019) Diabetes 68: 337-348
MeSH Terms: Animals, Cells, Cultured, Chromatin Immunoprecipitation, Chromosomes, Artificial, Bacterial, DNA Methylation, Female, Humans, In Vitro Techniques, Insulin-Secreting Cells, Maf Transcription Factors, Large, MafB Transcription Factor, Mice, Mice, Transgenic, Pregnancy, Tryptophan Hydroxylase
Show Abstract · Added January 8, 2019
The sustained expression of the MAFB transcription factor in human islet β-cells represents a distinct difference in mice. Moreover, mRNA expression of closely related and islet β-cell-enriched MAFA does not peak in humans until after 9 years of age. We show that the MAFA protein also is weakly produced within the juvenile human islet β-cell population and that expression is postnatally restricted in mouse β-cells by de novo DNA methylation. To gain insight into how MAFB affects human β-cells, we developed a mouse model to ectopically express in adult mouse β-cells using transcriptional control sequences. Coexpression of MafB with MafA had no overt impact on mouse β-cells, suggesting that the human adult β-cell MAFA/MAFB heterodimer is functionally equivalent to the mouse MafA homodimer. However, MafB alone was unable to rescue the islet β-cell defects in a mouse mutant lacking MafA in β-cells. Of note, transgenic production of MafB in β-cells elevated tryptophan hydroxylase 1 mRNA production during pregnancy, which drives the serotonin biosynthesis critical for adaptive maternal β-cell responses. Together, these studies provide novel insight into the role of MAFB in human islet β-cells.
© 2018 by the American Diabetes Association.
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15 MeSH Terms
Molecular and epidemiologic characterization of Wilms tumor from Baghdad, Iraq.
Phelps HM, Al-Jadiry MF, Corbitt NM, Pierce JM, Li B, Wei Q, Flores RR, Correa H, Uccini S, Frangoul H, Alsaadawi AR, Al-Badri SAF, Al-Darraji AF, Al-Saeed RM, Al-Hadad SA, Lovvorn Iii HN
(2018) World J Pediatr 14: 585-593
MeSH Terms: Adaptor Proteins, Signal Transducing, Child, Preschool, DNA Topoisomerases, Type II, Female, Homeodomain Proteins, Humans, Immunohistochemistry, Infant, Insulin-Like Growth Factor II, Iraq, Kidney Neoplasms, Male, Multiplex Polymerase Chain Reaction, Mutation, N-Myc Proto-Oncogene Protein, Nerve Tissue Proteins, Neural Cell Adhesion Molecules, Nuclear Proteins, Poly-ADP-Ribose Binding Proteins, Receptors, Retinoic Acid, Sequence Analysis, DNA, Transcription Factors, Tumor Suppressor Protein p53, Tumor Suppressor Proteins, WT1 Proteins, Wilms Tumor, beta Catenin
Show Abstract · Added January 28, 2019
BACKGROUND - Wilms tumor (WT) is the most common childhood kidney cancer worldwide, yet its incidence and clinical behavior vary according to race and access to adequate healthcare resources. To guide and streamline therapy in the war-torn and resource-constrained city of Baghdad, Iraq, we conducted a first-ever molecular analysis of 20 WT specimens to characterize the biological features of this lethal disease within this challenged population.
METHODS - Next-generation sequencing of ten target genes associated with WT development and treatment resistance (WT1, CTNNB1, WTX, IGF2, CITED1, SIX2, p53, N-MYC, CRABP2, and TOP2A) was completed. Immunohistochemistry was performed for 6 marker proteins of WT (WT1, CTNNB1, NCAM, CITED1, SIX2, and p53). Patient outcomes were compiled.
RESULTS - Mutations were detected in previously described WT "hot spots" (e.g., WT1 and CTNNB1) as well as novel loci that may be unique to the Iraqi population. Immunohistochemistry showed expression domains most typical of blastemal-predominant WT. Remarkably, despite the challenges facing families and care providers, only one child, with combined WT1 and CTNNB1 mutations, was confirmed dead from disease. Median clinical follow-up was 40.5 months (range 6-78 months).
CONCLUSIONS - These data suggest that WT biology within a population of Iraqi children manifests features both similar to and unique from disease variants in other regions of the world. These observations will help to risk stratify WT patients living in this difficult environment to more or less intensive therapies and to focus treatment on cell-specific targets.
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27 MeSH Terms
Methylglyoxal-derived posttranslational arginine modifications are abundant histone marks.
Galligan JJ, Wepy JA, Streeter MD, Kingsley PJ, Mitchener MM, Wauchope OR, Beavers WN, Rose KL, Wang T, Spiegel DA, Marnett LJ
(2018) Proc Natl Acad Sci U S A 115: 9228-9233
MeSH Terms: Arginine, HEK293 Cells, Histones, Humans, Lactoylglutathione Lyase, Protein Processing, Post-Translational, Pyruvaldehyde, Transcription, Genetic
Show Abstract · Added April 12, 2019
Histone posttranslational modifications (PTMs) regulate chromatin dynamics, DNA accessibility, and transcription to expand the genetic code. Many of these PTMs are produced through cellular metabolism to offer both feedback and feedforward regulation. Herein we describe the existence of Lys and Arg modifications on histones by a glycolytic by-product, methylglyoxal (MGO). Our data demonstrate that adduction of histones by MGO is an abundant modification, present at the same order of magnitude as Arg methylation. These modifications were detected on all four core histones at critical residues involved in both nucleosome stability and reader domain binding. In addition, MGO treatment of cells lacking the major detoxifying enzyme, glyoxalase 1, results in marked disruption of H2B acetylation and ubiquitylation without affecting H2A, H3, and H4 modifications. Using RNA sequencing, we show that MGO is capable of altering gene transcription, most notably in cells lacking GLO1. Finally, we show that the deglycase DJ-1 protects histones from adduction by MGO. Collectively, our findings demonstrate the existence of a previously undetected histone modification derived from glycolysis, which may have far-reaching implications for the control of gene expression and protein transcription linked to metabolism.
Copyright © 2018 the Author(s). Published by PNAS.
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ROCK-nmMyoII, Notch and gene-dosage link epithelial morphogenesis with cell fate in the pancreatic endocrine-progenitor niche.
Bankaitis ED, Bechard ME, Gu G, Magnuson MA, Wright CVE
(2018) Development 145:
MeSH Terms: Animals, Basic Helix-Loop-Helix Transcription Factors, Cell Differentiation, Cell Movement, Endocrine Cells, Gene Dosage, Mice, Mice, Transgenic, Nerve Tissue Proteins, Organogenesis, Pancreas, Receptors, Notch, Stem Cells, Transcriptional Activation, rho-Associated Kinases
Show Abstract · Added August 24, 2018
During mouse pancreas organogenesis, endocrine cells are born from progenitors residing in an epithelial plexus niche. After a period in a lineage-primed state, progenitors become endocrine committed via upregulation of We find that the to transition is associated with distinct stages of an epithelial egression process: narrowing the apical surface of the cell, basalward cell movement and eventual cell-rear detachment from the apical lumen surface to allow clustering as nascent islets under the basement membrane. Apical narrowing, basalward movement and transcriptional upregulation still occur without Neurog3 protein, suggesting that morphogenetic cues deployed within the plexus initiate endocrine commitment upstream or independently of Neurog3. Neurog3 is required for cell-rear detachment and complete endocrine-cell birth. The ROCK-nmMyoII pathway coordinates epithelial-cell morphogenesis and the progression through -expressing states. NmMyoII is necessary for apical narrowing, basalward cell displacement and upregulation, but all three are limited by ROCK activity. We propose that ROCK-nmMyoII activity, gene-dose and Notch signaling integrate endocrine fate allocation with epithelial plexus growth and morphogenesis, representing a feedback control circuit that coordinates morphogenesis with lineage diversification in the endocrine-birth niche.
© 2018. Published by The Company of Biologists Ltd.
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15 MeSH Terms
Supplementation of p40, a Lactobacillus rhamnosus GG-derived protein, in early life promotes epidermal growth factor receptor-dependent intestinal development and long-term health outcomes.
Shen X, Liu L, Peek RM, Acra SA, Moore DJ, Wilson KT, He F, Polk DB, Yan F
(2018) Mucosal Immunol 11: 1316-1328
MeSH Terms: Animals, Bacterial Proteins, Cell Differentiation, Cell Proliferation, Epithelial Cells, ErbB Receptors, Female, Hydrogels, Immunity, Innate, Immunoglobulin A, Intestinal Mucosa, Lactobacillus rhamnosus, Mice, Mice, Inbred C57BL, Probiotics, T-Lymphocytes, Regulatory, Tight Junctions, Time, Transcriptional Activation
Show Abstract · Added June 8, 2018
The beneficial effects of the gut microbiota on growth in early life are well known. However, knowledge about the mechanisms underlying regulating intestinal development by the microbiota is limited. p40, a Lactobacillus rhamnosus GG-derived protein, transactivates epidermal growth factor receptor (EGFR) in intestinal epithelial cells for protecting the intestinal epithelium against injury and inflammation. Here, we developed p40-containing pectin/zein hydrogels for targeted delivery of p40 to the small intestine and the colon. Treatment with p40-containing hydrogels from postnatal day 2 to 21 significantly enhanced bodyweight gain prior to weaning and functional maturation of the intestine, including intestinal epithelial cell proliferation, differentiation, and tight junction formation, and IgA production in early life in wild-type mice. These p40-induced effects were abolished in mice with specific deletion of EGFR in intestinal epithelial cells, suggesting that transactivation of EGFR in intestinal epithelial cells may mediate p40-regulated intestinal development. Furthermore, neonatal p40 treatment reduced the susceptibility to intestinal injury and colitis and promoted protective immune responses, including IgA production and differentiation of regulatory T cells, in adult mice. These findings reveal novel roles of neonatal supplementation of probiotic-derived factors in promoting EGFR-mediated maturation of intestinal functions and innate immunity, which likely promote long-term beneficial outcomes.
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19 MeSH Terms
Striking parallels between carotid body glomus cell and adrenal chromaffin cell development.
Hockman D, Adameyko I, Kaucka M, Barraud P, Otani T, Hunt A, Hartwig AC, Sock E, Waithe D, Franck MCM, Ernfors P, Ehinger S, Howard MJ, Brown N, Reese J, Baker CVH
(2018) Dev Biol 444 Suppl 1: S308-S324
MeSH Terms: Adrenal Glands, Animals, Basic Helix-Loop-Helix Transcription Factors, Body Patterning, Carotid Body, Cell Differentiation, Cell Hypoxia, Chick Embryo, Chickens, Chromaffin Cells, Mice, Mice, Knockout, Myelin Proteolipid Protein, Neural Crest, Neurons, Pericytes, Transcription Factors
Show Abstract · Added May 30, 2018
Carotid body glomus cells mediate essential reflex responses to arterial blood hypoxia. They are dopaminergic and secrete growth factors that support dopaminergic neurons, making the carotid body a potential source of patient-specific cells for Parkinson's disease therapy. Like adrenal chromaffin cells, which are also hypoxia-sensitive, glomus cells are neural crest-derived and require the transcription factors Ascl1 and Phox2b; otherwise, their development is little understood at the molecular level. Here, analysis in chicken and mouse reveals further striking molecular parallels, though also some differences, between glomus and adrenal chromaffin cell development. Moreover, histology has long suggested that glomus cell precursors are 'émigrés' from neighbouring ganglia/nerves, while multipotent nerve-associated glial cells are now known to make a significant contribution to the adrenal chromaffin cell population in the mouse. We present conditional genetic lineage-tracing data from mice supporting the hypothesis that progenitors expressing the glial marker proteolipid protein 1, presumably located in adjacent ganglia/nerves, also contribute to glomus cells. Finally, we resolve a paradox for the 'émigré' hypothesis in the chicken - where the nearest ganglion to the carotid body is the nodose, in which the satellite glia are neural crest-derived, but the neurons are almost entirely placode-derived - by fate-mapping putative nodose neuronal 'émigrés' to the neural crest.
Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
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17 MeSH Terms
ARID1A Maintains Differentiation of Pancreatic Ductal Cells and Inhibits Development of Pancreatic Ductal Adenocarcinoma in Mice.
Kimura Y, Fukuda A, Ogawa S, Maruno T, Takada Y, Tsuda M, Hiramatsu Y, Araki O, Nagao M, Yoshikawa T, Ikuta K, Yoshioka T, Wang Z, Akiyama H, Wright CV, Takaori K, Uemoto S, Chiba T, Seno H
(2018) Gastroenterology 155: 194-209.e2
MeSH Terms: Adenocarcinoma in Situ, Animals, Carcinogenesis, Carcinoma, Pancreatic Ductal, Cell Culture Techniques, Cell Differentiation, DNA-Binding Proteins, Mice, Nuclear Proteins, Pancreatic Ducts, Pancreatic Neoplasms, Proto-Oncogene Proteins p21(ras), SOX9 Transcription Factor
Show Abstract · Added April 3, 2018
BACKGROUND & AIMS - The ARID1A gene encodes a protein that is part of the large adenosine triphosphate (ATP)-dependent chromatin remodeling complex SWI/SNF and is frequently mutated in human pancreatic ductal adenocarcinomas (PDACs). We investigated the functions of ARID1A during formation of PDACs in mice.
METHODS - We performed studies with Ptf1a-Cre;Kras mice, which express activated Kras in the pancreas and develop pancreatic intraepithelial neoplasias (PanINs), as well as those with disruption of Aird1a (Ptf1a-Cre;Kras;Arid1a mice) or disruption of Brg1 (encodes a catalytic ATPase of the SWI/SNF complex) (Ptf1a-Cre;Kras; Brg1mice). Pancreatic ductal cells (PDCs) were isolated from Arid1a mice and from Arid1a;SOX9OE mice, which overexpress human SOX9 upon infection with an adenovirus-expressing Cre recombinase. Pancreatic tissues were collected from all mice and analyzed by histology and immunohistochemistry; cells were isolated and grown in 2-dimensional and 3-dimensional cultures. We performed microarray analyses to compare gene expression patterns in intraductal papillary mucinous neoplasms (IPMNs) from the different strains of mice. We obtained 58 samples of IPMNs and 44 samples of PDACs from patients who underwent pancreatectomy in Japan and analyzed them by immunohistochemistry.
RESULTS - Ptf1a-Cre;Kras mice developed PanINs, whereas Ptf1a-Cre;Kras;Arid1a mice developed IPMNs and PDACs; IPMNs originated from PDCs. ARID1A-deficient IPMNs did not express SOX9. ARID1A-deficient PDCs had reduced expression of SOX9 and dedifferentiated in culture. Overexpression of SOX9 in these cells allowed them to differentiate and prevented dilation of ducts. Among mice with pancreatic expression of activated Kras, those with disruption of Arid1a developed fewer PDACs from IPMNs than mice with disruption of Brg1. ARID1A-deficient IPMNs had reduced activity of the mTOR pathway. Human IPMN and PDAC specimens had reduced levels of ARID1A, SOX9, and phosphorylated S6 (a marker of mTOR pathway activation). Levels of ARID1A correlated with levels of SOX9 and phosphorylated S6.
CONCLUSIONS - ARID1A regulates expression of SOX9, activation of the mTOR pathway, and differentiation of PDCs. ARID1A inhibits formation of PDACs from IPMNs in mice with pancreatic expression of activated KRAS and is down-regulated in IPMN and PDAC tissues from patients.
Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.
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13 MeSH Terms
B Cell-Intrinsic mTORC1 Promotes Germinal Center-Defining Transcription Factor Gene Expression, Somatic Hypermutation, and Memory B Cell Generation in Humoral Immunity.
Raybuck AL, Cho SH, Li J, Rogers MC, Lee K, Williams CL, Shlomchik M, Thomas JW, Chen J, Williams JV, Boothby MR
(2018) J Immunol 200: 2627-2639
MeSH Terms: Animals, B-Lymphocytes, Cell Differentiation, Gene Expression, Germinal Center, Immunity, Humoral, Immunoglobulin G, Immunologic Memory, Lymphocyte Activation, Mechanistic Target of Rapamycin Complex 1, Mice, Mice, Inbred C57BL, Mutation, Plasma Cells, Proto-Oncogene Proteins c-bcl-6, Signal Transduction, Transcription Factors
Show Abstract · Added March 14, 2018
B lymphocytes migrate among varied microenvironmental niches during diversification, selection, and conversion to memory or Ab-secreting plasma cells. Aspects of the nutrient milieu differ within these lymphoid microenvironments and can influence signaling molecules such as the mechanistic target of rapamycin (mTOR). However, much remains to be elucidated as to the B cell-intrinsic functions of nutrient-sensing signal transducers that modulate B cell differentiation or Ab affinity. We now show that the amino acid-sensing mTOR complex 1 (mTORC1) is vital for induction of Bcl6-a key transcriptional regulator of the germinal center (GC) fate-in activated B lymphocytes. Accordingly, disruption of mTORC1 after B cell development and activation led to reduced populations of Ag-specific memory B cells as well as plasma cells and GC B cells. In addition, induction of the germ line transcript that guides activation-induced deaminase in selection of the IgG1 H chain region during class switching required mTORC1. Expression of the somatic mutator activation-induced deaminase was reduced by a lack of mTORC1 in B cells, whereas point mutation frequencies in Ag-specific GC-phenotype B cells were only halved. These effects culminated in a B cell-intrinsic defect that impacted an antiviral Ab response and drastically impaired generation of high-affinity IgG1. Collectively, these data establish that mTORC1 governs critical B cell-intrinsic mechanisms essential for establishment of GC differentiation and effective Ab production.
Copyright © 2018 by The American Association of Immunologists, Inc.
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17 MeSH Terms