Setser J.W.,7 Massachusetts Avenue |
Lingaraju G.M.,Center for Environmental Health science |
Lingaraju G.M.,Friedrich Miescher Institute for Biomedical Research |
Davis C.A.,7 Massachusetts Avenue |
And 6 more authors.
Biochemistry | Year: 2012
To efficiently repair DNA, human alkyladenine DNA glycosylase (AAG) must search the million-fold excess of unmodified DNA bases to find a handful of DNA lesions. Such a search can be facilitated by the ability of glycosylases, like AAG, to interact with DNA using two affinities: a lower-affinity interaction in a searching process and a higher-affinity interaction for catalytic repair. Here, we present crystal structures of AAG trapped in two DNA-bound states. The lower-affinity depiction allows us to investigate, for the first time, the conformation of this protein in the absence of a tightly bound DNA adduct. We find that active site residues of AAG involved in binding lesion bases are in a disordered state. Furthermore, two loops that contribute significantly to the positive electrostatic surface of AAG are disordered. Additionally, a higher-affinity state of AAG captured here provides a fortuitous snapshot of how this enzyme interacts with a DNA adduct that resembles a one-base loop. © 2011 American Chemical Society.
Brown B.D.,University of Montana |
Harris J.L.,University of Montana |
Parker M.,Rocky Boy Tribal Health |
Ricci C.,University of Montana |
Noonan C.,Center for Environmental Health science
Diabetes Educator | Year: 2010
Purpose The purpose of this study was to use a community-based participatory research (CBPR) approach to translate the original Diabetes Prevention Program (DPP) to be age and culturally specific for American Indian (AI) youth. Methods Tribally enrolled members on 2 Montana Indian reservations conducted focus groups and interviews to discuss community members' perspectives of factors that encouraged or were barriers to healthy diet and exercise behaviors in AI youth. In total, 31 community members, aged 10 to 68 years old, participated in 4 focus groups and 14 individual interviews. Participants were self-identified as elder, cultural expert, tribal health worker, educator, parent/guardian, youth, or school food service worker. Researchers analyzed transcripts based on inductive methods of grounded theory. Results Data analysis revealed translating the DPP to youth was contingent on the lessons incorporating cultural strategies for healthy behaviors in youth such as berry picking, gardening, horseback riding, and dancing; improving knowledge and access to healthy foods and physical activity for youth and their parents; having interactive, hands-on learning activities for healthy lifestyles in the DPP lessons; using a group format and tribal members to deliver the DPP lessons; and having tribal elders talk to youth about the importance of adopting healthy behaviors when they are young. Conclusions A CBPR approach engaged community members to identify strategies inherent in their culture, tradition, and environment that could effectively translate the DPP to Montana Indian youth living in rural reservation communities. © 2010 The Author(s).
Beamer G.L.,Tufts University |
Seaver B.P.,University of Montana |
Jessop F.,University of Montana |
Jessop F.,Center for Environmental Health science |
And 3 more authors.
Frontiers in Immunology | Year: 2016
Numerous studies have examined the relationship between alveolar macrophages (AMs) and crystalline silica (SiO2) using in vitro and in vivo immunotoxicity models; however, exactly how exposure to SiO2 alters the functionality of AM and the potential consequences for immunity to respiratory pathogens remains largely unknown. Because recognition and clearance of inhaled particulates and microbes are largely mediated by pattern recognition receptors (PRRs) on the surface of AM, we hypothesized that exposure to SiO2 limits the ability of AM to respond to bacterial challenge by altering PRR expression. Alveolar and bone marrow-derived macrophages downregulate TLR2 expression following acute SiO2 exposure (e.g., 4 h). Interestingly, these responses were dependent on interactions between SiO2 and the class A scavenger receptor CD204, but not MARCO. Furthermore, SiO2 exposure decreased uptake of fluorescently labeled Pam2CSK4 and Pam3CSK4, resulting in reduced secretion of IL-1β, but not IL-6. Collectively, our data suggest that SiO2 exposure alters AM phenotype, which in turn affects their ability to uptake and respond to bacterial lipoproteins. © 2016 Beamer, Seaver, Jessop, Shepherd and Beamer.
Shaw J.R.,Indiana University Bloomington |
Shaw J.R.,Mt Desert Island Biological Laboratory |
VanderHeide J.,Mt Desert Island Biological Laboratory |
LaCasse T.,Mt Desert Island Biological Laboratory |
And 3 more authors.
Aquatic Toxicology | Year: 2010
Seawater acclimation in killifish, Fundulus heteroclitus, is mediated in part by a rapid (1h) translocation of CFTR Cl- channels from an intracellular pool to the plasma membrane in gill and increased CFTR-mediated Cl- secretion. This effect is mediated by serum and glucocorticoid-inducible kinase 1 (SGK1), which is stimulated by plasma hypertonicity rather than cortisol. Since arsenic exposure prevents acclimation to seawater by decreasing CFTR protein levels we tested the hypothesis that arsenic (as sodium arsenite) blocks acclimation to seawater by down regulating SGK1 expression. Freshwater adapted killifish were exposed to arsenic (48h) and transferred to seawater containing arsenic, and SGK and CFTR expression were measured. Arsenic reduced the seawater induced increase in SGK1 mRNA and protein abundance, and reduced both the total amount of CFTR and the amount of CFTR in the plasma membrane. The decrease in membrane CFTR reduced Cl- secretion. Arsenic also increased the amount of ubiquitinated CFTR and its degradation by the lysosome. Thus, we propose a model whereby arsenic reduces the ability of killifish to acclimate to seawater by blocking the seawater induced increase in SGK1, which results in increased ubiquitination and degradation of CFTR. © 2010 Elsevier B.V.
Tsuji T.,Kyoto Prefectural University of Medicine |
Naito Y.,Kyoto Prefectural University of Medicine |
Takagi T.,Kyoto Prefectural University of Medicine |
Kugai M.,Kyoto Prefectural University of Medicine |
And 17 more authors.
International Journal of Molecular Medicine | Year: 2013
Metallothioneins (MTs) are a family of cysteine-rich low molecular-weight proteins that can act as reactive oxygen species scavengers. Although it is known that the induction of MT expression suppresses various inflammatory disorders, the role of MTs in intestinal inflammation remains unclear. In this study, we investigated the effects of dextran sulfate sodium (DSS) administration in mice with targeted deletions of the MT-I/II genes. Acute colitis was induced by 2% DSS in male MT-I/II double knockout (MT-null) and C57BL/6 (wild-type) mice. The disease activity index (DAI) was determined on a daily basis for each animal, and consisted of a calculated score based on changes in body weight, stool consistency and intestinal bleeding. Histology, colon length, myeloperoxidase (MPO) activity and colonic mRNA expression and the concentration of inflammatory cytokines were evaluated by real-time-PCR and enzyme-linked immunosorbent assay (ELISA). The localization of MTs and macrophages was determined by immunohistological and immunofluorescence staining. To investigate the role of MTs in macrophages, peritoneal macrophages were isolated and their responses to lipopolysaccharide were measured. Following DSS administration, the DAI score increased in a time-dependent manner and was significantly enhanced in the MT-I/II knockout mice. Colonic MPO activity levels and inflammatory cytokines [tumor necrosis factor (TNF)-α, interferon (IFN)-γ and interleukin (IL)-17] production increased following DSS administration, and these increases were significantly enhanced in the MT-I/II knockout mice compared with the wild-type mice. MT-positive cells were detected in the lamina propria and submucosal layer by immunohistochemical and immunofluorescence staining, and were mainly co-localized in F4/80-positive macrophages. The production of inflammatory cytokines (TNF-α, IFN-γ and IL-17) from isolated peritoneal macrophages increased following lipopolysaccharide stimulation, and these increases were significantly enhanced in the macrophages obtained from the MT-I/II knockout mice. These data indicate that MTs play an important role in the prevention of colonic mucosal inflammation in a mouse model of DSS-induced colitis, thus suggesting that endogenous MTs play a protective role against intestinal inflammation.
Ebrahimkhani M.R.,Northumbria University |
Ebrahimkhani M.R.,Center for Environmental Health science |
Oakley F.,Northumbria University |
Murphy L.B.,Northumbria University |
And 16 more authors.
Nature Medicine | Year: 2011
Tissue homeostasis requires an effective, limited wound-healing response to injury. In chronic disease, failure to regenerate parenchymal tissue leads to the replacement of lost cellular mass with a fibrotic matrix. The mechanisms that dictate the balance of cell regeneration and fibrogenesis are not well understood 1. Here we report that fibrogenic hepatic stellate cells (HSCs) in the liver are negative regulators of hepatocyte regeneration. This negative regulatory function requires stimulation of the 5-hydroxytryptamine 2B receptor (5-HT 2B) on HSCs by serotonin, which activates expression of transforming growth factor β1 (TGF-β1), a powerful suppressor of hepatocyte proliferation, through signaling by mitogen-activated protein kinase 1 (ERK) and the transcription factor JunD. Selective antagonism of 5-HT 2B enhanced hepatocyte growth in models of acute and chronic liver injury. We also observed similar effects in mice lacking 5-HT 2B or JunD or upon selective depletion of HSCs in wild-type mice. Antagonism of 5-HT 2B attenuated fibrogenesis and improved liver function in disease models in which fibrosis was pre-established and progressive. Pharmacological targeting of 5-HT 2B is clinically safe in humans and may be therapeutic in chronic liver disease.
Notch E.G.,Center for Environmental Health science |
Notch E.G.,Western New England University |
Goodale B.C.,Center for Environmental Health science |
Barnaby R.,Center for Environmental Health science |
And 5 more authors.
PLoS ONE | Year: 2015
Arsenic is the number one contaminant of concern with regard to human health according to the World Health Organization. Epidemiological studies on Asian and South American populations have linked arsenic exposure with an increased incidence of lung disease, including pneumonia, and chronic obstructive pulmonary disease, both of which are associated with bacterial infection. However, little is known about the effects of low dose arsenic exposure, or the contributions of organic arsenic to the innate immune response to bacterial infection. This study examined the effects on Pseudomonas aeruginosa (P. aeruginosa) induced cytokine secretion by human bronchial epithelial cells (HBEC) by inorganic sodium arsenite (iAsIII) and two major metabolites, monomethylarsonous acid (MMAIII) and dimethylarsenic acid (DMAV), at concentrations relevant to the U.S. population. Neither iAsIII nor DMAV altered P. aeruginosa induced cytokine secretion. By contrast, MMAIII increased P. aeruginosa induced secretion of IL-8, IL-6 and CXCL2. A combination of iAsIII, MMAIII and DMAV (10 pbb total) reduced IL-8 and CXCL1 secretion. These data demonstrate for the first time that exposure to MMAIII alone, and a combination of iAsIII, MMAIII and DMAV at levels relevant to the U.S. may have negative effects on the innate immune response of human bronchial epithelial cells to P. aeruginosa. Copyright: © 2015 Bastin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PubMed | Dartmouth College and Center for Environmental Health science
Type: Journal Article | Journal: PloS one | Year: 2015
Arsenic is the number one contaminant of concern with regard to human health according to the World Health Organization. Epidemiological studies on Asian and South American populations have linked arsenic exposure with an increased incidence of lung disease, including pneumonia, and chronic obstructive pulmonary disease, both of which are associated with bacterial infection. However, little is known about the effects of low dose arsenic exposure, or the contributions of organic arsenic to the innate immune response to bacterial infection. This study examined the effects on Pseudomonas aeruginosa (P. aeruginosa) induced cytokine secretion by human bronchial epithelial cells (HBEC) by inorganic sodium arsenite (iAsIII) and two major metabolites, monomethylarsonous acid (MMAIII) and dimethylarsenic acid (DMAV), at concentrations relevant to the U.S.Neither iAsIII nor DMAV altered P. aeruginosa induced cytokine secretion. By contrast, MMAIII increased P. aeruginosa induced secretion of IL-8, IL-6 and CXCL2. A combination of iAsIII, MMAIII and DMAV (10 pbb total) reduced IL-8 and CXCL1 secretion. These data demonstrate for the first time that exposure to MMAIII alone, and a combination of iAsIII, MMAIII and DMAV at levels relevant to the U.S. may have negative effects on the innate immune response of human bronchial epithelial cells to P. aeruginosa.
PubMed | Center for Environmental Health science and Mississippi State University
Type: Journal Article | Journal: Toxicological sciences : an official journal of the Society of Toxicology | Year: 2016
Exposure to p,p-DDE (DDE), the main bioaccumulative metabolite of the organochlorine insecticide p,p-DDT, is associated with a higher prevalence of obesity, dyslipidemia, insulin resistance, metabolic syndrome, and immunomodulation. The present study was carried out to determine whether DDE perturbs adipose tissue homeostasis through modulation of macrophage function. Treatment with DDE or a cyclooxygenase-2 inhibitor prior to lipopolysaccharide exposure significantly decreased production of prostaglandins (PG) from J774a.1 macrophages invitro. Similarly, J774A.1 cell lysates incubated with DDE or a specific cyclooxygenase-2 inhibitor (NS-398) produced significantly less PGE2 and PGF2. Macrophage polarization studies revealed a pattern of DDE effects that were not fully consistent with a purely pro- or purely anti- M1 or M2 effect. However, DDE suppressed expression of two M1 markers (induced by an M1 stimulus) and enhanced expression of an M2 marker (induced by an M2 stimulus). Further studies including assessment of macrophage function are needed to fully characterize the effects of DDE on macrophage polarization. Obesity is characterized by an increase in the number of resident adipose tissue macrophages. To assess monocyte/macrophage recruitment to the adipose tissue invivo, male C57Bl/6H mice were treated with 2mg/kg DDE or corn oil vehicle for 5 days by gavage. Epididymal fat pads were digested and macrophage populations were analyzed by flow cytometry. In DDE-treated animals, there was a significant increase (37%) in F4/80(+)CD11b(+) macrophages/g of epididymal adipose over vehicle (P<.05). Together, these results suggest a role for DDE in the enhancement of adipose tissue macrophage recruitment and/or proliferation, as well as modulation of immune cell function that may contribute to the etiology of metabolic diseases associated with organochlorine exposure.