Publications by authors named "Lindsay Evans"

17 Publications

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Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets.

Cell Rep 2021 Nov;37(8):110037

Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston 02115, MA, USA; Department of Medicine, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA. Electronic address:

Glucose metabolism modulates the islet β cell responses to diabetogenic stress, including inflammation. Here, we probed the metabolic mechanisms that underlie the protective effect of glucose in inflammation by interrogating the metabolite profiles of primary islets from human donors and identified de novo glutathione synthesis as a prominent glucose-driven pro-survival pathway. We find that pyruvate carboxylase is required for glutathione synthesis in islets and promotes their antioxidant capacity to counter inflammation and nitrosative stress. Loss- and gain-of-function studies indicate that pyruvate carboxylase is necessary and sufficient to mediate the metabolic input from glucose into glutathione synthesis and the oxidative stress response. Altered redox metabolism and cellular capacity to replenish glutathione pools are relevant in multiple pathologies beyond obesity and diabetes. Our findings reveal a direct interplay between glucose metabolism and glutathione biosynthesis via pyruvate carboxylase. This metabolic axis may also have implications in other settings where sustaining glutathione is essential.
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http://dx.doi.org/10.1016/j.celrep.2021.110037DOI Listing
November 2021

Colistin kills bacteria by targeting lipopolysaccharide in the cytoplasmic membrane.

Elife 2021 04 6;10. Epub 2021 Apr 6.

MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom.

Colistin is an antibiotic of last resort, but has poor efficacy and resistance is a growing problem. Whilst it is well established that colistin disrupts the bacterial outer membrane (OM) by selectively targeting lipopolysaccharide (LPS), it was unclear how this led to bacterial killing. We discovered that MCR-1 mediated colistin resistance in is due to modified LPS at the cytoplasmic rather than OM. In doing so, we also demonstrated that colistin exerts bactericidal activity by targeting LPS in the cytoplasmic membrane (CM). We then exploited this information to devise a new therapeutic approach. Using the LPS transport inhibitor murepavadin, we were able to cause LPS accumulation in the CM of , which resulted in increased susceptibility to colistin in vitro and improved treatment efficacy in vivo. These findings reveal new insight into the mechanism by which colistin kills bacteria, providing the foundations for novel approaches to enhance therapeutic outcomes.
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http://dx.doi.org/10.7554/eLife.65836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8096433PMC
April 2021

Glucose-dependent partitioning of arginine to the urea cycle protects β-cells from inflammation.

Nat Metab 2020 05 11;2(5):432-446. Epub 2020 May 11.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Chronic inflammation is linked to diverse disease processes, but the intrinsic mechanisms that determine cellular sensitivity to inflammation are incompletely understood. Here, we show the contribution of glucose metabolism to inflammation-induced changes in the survival of pancreatic islet β-cells. Using metabolomic, biochemical and functional analyses, we investigate the protective versus non-protective effects of glucose in the presence of pro-inflammatory cytokines. When protective, glucose metabolism augments anaplerotic input into the TCA cycle via pyruvate carboxylase (PC) activity, leading to increased aspartate levels. This metabolic mechanism supports the argininosuccinate shunt, which fuels ureagenesis from arginine and conversely diminishes arginine utilization for production of nitric oxide (NO), a chief mediator of inflammatory cytotoxicity. Activation of the PC-urea cycle axis is sufficient to suppress NO synthesis and shield cells from death in the context of inflammation and other stress paradigms. Overall, these studies uncover a previously unappreciated link between glucose metabolism and arginine-utilizing pathways via PC-directed ureagenesis as a protective mechanism.
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http://dx.doi.org/10.1038/s42255-020-0199-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7568475PMC
May 2020

Identification of a potent small-molecule inhibitor of bacterial DNA repair that potentiates quinolone antibiotic activity in methicillin-resistant Staphylococcus aureus.

Bioorg Med Chem 2019 10 15;27(20):114962. Epub 2019 Jun 15.

Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK. Electronic address:

The global emergence of antibiotic resistance is one of the most serious challenges facing modern medicine. There is an urgent need for validation of new drug targets and the development of small molecules with novel mechanisms of action. We therefore sought to inhibit bacterial DNA repair mediated by the AddAB/RecBCD protein complexes as a means to sensitize bacteria to DNA damage caused by the host immune system or quinolone antibiotics. A rational, hypothesis-driven compound optimization identified IMP-1700 as a cell-active, nanomolar potency compound. IMP-1700 sensitized multidrug-resistant Staphylococcus aureus to the fluoroquinolone antibiotic ciprofloxacin, where resistance results from a point mutation in the fluoroquinolone target, DNA gyrase. Cellular reporter assays indicated IMP-1700 inhibited the bacterial SOS-response to DNA damage, and compound-functionalized Sepharose successfully pulled-down the AddAB repair complex. This work provides validation of bacterial DNA repair as a novel therapeutic target and delivers IMP-1700 as a tool molecule and starting point for therapeutic development to address the pressing challenge of antibiotic resistance.
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http://dx.doi.org/10.1016/j.bmc.2019.06.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6892255PMC
October 2019

Exploitation of Antibiotic Resistance as a Novel Drug Target: Development of a β-Lactamase-Activated Antibacterial Prodrug.

J Med Chem 2019 05 1;62(9):4411-4425. Epub 2019 May 1.

MRC Centre for Molecular Bacteriology and Infection , Imperial College London , SW7 2AZ London , United Kingdom.

Expression of β-lactamase is the single most prevalent determinant of antibiotic resistance, rendering bacteria resistant to β-lactam antibiotics. In this article, we describe the development of an antibiotic prodrug that combines ciprofloxacin with a β-lactamase-cleavable motif. The prodrug is only bactericidal after activation by β-lactamase. Bactericidal activity comparable to ciprofloxacin is demonstrated against clinically relevant E. coli isolates expressing diverse β-lactamases; bactericidal activity was not observed in strains without β-lactamase. These findings demonstrate that it is possible to exploit antibiotic resistance to selectively target β-lactamase-producing bacteria using our prodrug approach, without adversely affecting bacteria that do not produce β-lactamase. This paves the way for selective targeting of drug-resistant pathogens without disrupting or selecting for resistance within the microbiota, reducing the rate of secondary infections and subsequent antibiotic use.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511942PMC
May 2019

Privileged Structures and Polypharmacology within and between Protein Families.

ACS Med Chem Lett 2018 Dec 16;9(12):1199-1204. Epub 2018 Nov 16.

Cancer Research UK Cancer Therapeutics Unit and Division of Structural Biology, The Institute of Cancer Research, London SW7 3RP, United Kingdom.

Polypharmacology is often a key contributor to the efficacy of a drug, but is also a potential risk. We investigated two hits discovered via a cell-based phenotypic screen, the CDK9 inhibitor CCT250006 () and the pirin ligand CCT245232 (), to establish methodology to elucidate their secondary protein targets. Using computational pocket-based analysis, we discovered intrafamily polypharmacology for our kinase inhibitor, despite little overall sequence identity. The interfamily polypharmacology of with B-Raf was used to discover a novel pirin ligand from a very small but privileged compound library despite no apparent ligand or binding site similarity. Our data demonstrates that in areas of drug discovery where intrafamily polypharmacology is often an issue, ligand dissimilarity cannot necessarily be used to assume different off-target profiles and that understanding interfamily polypharmacology will be important in the future to reduce the risk of idiopathic toxicity and in the design of screening libraries.
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http://dx.doi.org/10.1021/acsmedchemlett.8b00364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295861PMC
December 2018

Targeting secondary protein complexes in drug discovery: studying the druggability and chemical biology of the HSP70/BAG1 complex.

Chem Commun (Camb) 2017 May;53(37):5167-5170

Cancer Research UK Cancer Therapeutics Unit at The Institute of Cancer Research, London SW7 3RP, UK.

Proteins typically carry out their biological functions as multi-protein complexes, which can significantly affect the affinity of small-molecule inhibitors. HSP70 is an important target in oncology, so to study its chemical biology and the drug discovery potential of the HSP70/BAG1 complex, we designed a high-affinity non-nucleotide fluorescence polarisation probe.
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http://dx.doi.org/10.1039/c7cc01376kDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5708526PMC
May 2017

Discovery of a Chemical Probe Bisamide (CCT251236): An Orally Bioavailable Efficacious Pirin Ligand from a Heat Shock Transcription Factor 1 (HSF1) Phenotypic Screen.

J Med Chem 2017 01 22;60(1):180-201. Epub 2016 Dec 22.

Cancer Research UK Cancer Therapeutics Unit at The Institute of Cancer Research , London SW7 3RP, United Kingdom.

Phenotypic screens, which focus on measuring and quantifying discrete cellular changes rather than affinity for individual recombinant proteins, have recently attracted renewed interest as an efficient strategy for drug discovery. In this article, we describe the discovery of a new chemical probe, bisamide (CCT251236), identified using an unbiased phenotypic screen to detect inhibitors of the HSF1 stress pathway. The chemical probe is orally bioavailable and displays efficacy in a human ovarian carcinoma xenograft model. By developing cell-based SAR and using chemical proteomics, we identified pirin as a high affinity molecular target, which was confirmed by SPR and crystallography.
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http://dx.doi.org/10.1021/acs.jmedchem.6b01055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6014687PMC
January 2017

Investigating Apoptozole as a Chemical Probe for HSP70 Inhibition.

PLoS One 2015 12;10(10):e0140006. Epub 2015 Oct 12.

Cancer Research UK Cancer Therapeutics Unit at The Institute of Cancer Research, London SW7 3RP, United Kingdom.

The use of chemical tools to validate clinical targets has gained in popularity over recent years and the importance of understanding the activity, selectivity and mechanism of action of these compounds is well recognized. Dysregulation of the HSP70 protein family has been linked to multiple cancer types and drug resistance, highlighting their importance as popular targets for anti-cancer drug development. Apoptozole is a recently identified small molecule, which has been reported to possess strong affinity for the HSP70 isoforms HSP72 and HSC70. We investigated apoptozole as a potential chemical tool for HSP70 inhibition. Unfortunately, using both biochemical and biophysical techniques, we were unable to find any experimental evidence that apoptozole binds to HSP70 in a specific and developable way. Instead, we provide experimental evidence that apoptozole forms aggregates under aqueous conditions that could interact with HSP70 proteins in a non-specific manner.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0140006PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4601772PMC
July 2016

Concurrent and Short-Term Prospective Relations among Neurocognitive Functioning, Coping, and Depressive Symptoms in Youth.

J Clin Child Adolesc Psychol 2016 4;45(1):6-20. Epub 2015 Feb 4.

a Department of Psychology and Human Development , Vanderbilt University.

The present short-term longitudinal study examined the concurrent and prospective relations among executive functioning (i.e., working memory and cognitive flexibility), coping (primary and secondary control coping), and depressive symptoms in children. Participants were 192 children between 9 and 15 years old (M age = 12.36 years, SD = 1.77) recruited from the community. Youth were individually administered neuropsychological measures of executive functioning and intelligence and completed self-report measures of executive dysfunction, coping, and depressive symptoms in small groups; the latter two measures were completed again 4 months later (Time 2 [T2]). Linear regression analyses were used to examine direct associations among executive functions, coping, and depressive symptoms, and a bootstrapping procedure was used to test indirect effects of executive functioning on depressive symptoms through coping. Significant prospective relations were found between working memory measured at Time 1 (T1) and both primary and secondary control coping measured at T2, controlling for T1 coping. T1 cognitive flexibility significantly predicted T2 secondary control coping, controlling for T1 coping. Working memory deficits significantly predicted increases in depressive symptoms 4 months later, controlling for T1 depressive symptoms. Bootstrap analyses revealed that primary and secondary control coping each partially mediated the relation between working memory and depressive symptoms; secondary control coping partially mediated the relation between cognitive flexibility and depressive symptoms. Coping may be one pathway through which deficits in executive functioning contribute to children's symptoms of depression.
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http://dx.doi.org/10.1080/15374416.2014.982282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4799276PMC
September 2016

Longitudinal relations between stress and depressive symptoms in youth: coping as a mediator.

J Abnorm Child Psychol 2015 Feb;43(2):355-68

Department of Psychology and Human Development, Vanderbilt University, 0552 Peabody, 230 Appleton Place, Nashville, TN, 37203-5721, USA,

The present prospective study examined the relations among stressful life events, coping, and depressive symptoms in children at varied risk for depression. Participants were 227 children between 7 and 17 years old (mean age = 12.13 years, SD = 2.31, 54.6 % female) who were part of a longitudinal study of depressed and nondepressed parents and their children. Youth completed measures assessing stressful life events and coping strategies at four time points over 22 months. Children's depressive symptoms were assessed at each time point by clinical interviews of parents and children, and children's self-report. Structural equation modeling indicated that stressful life events significantly predicted subsequent depressive symptoms. Bootstrap analyses of the indirect effects in three different models revealed that primary control engagement coping and disengagement coping strategies partially mediated the relation between stressful life events and children's depressive symptoms across time. Regarding the direction of effects, more consistent relations were found for coping as a mediator of the link from stress to depressive symptoms than from symptoms to stress. Thus, one potential mechanism by which stressful life events may contribute to depressive symptoms in children is through less use of primary control coping and greater use of disengagement coping strategies. This is consistent with the view that the adverse effects of stress may contribute to impairments in the ability to cope effectively.
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http://dx.doi.org/10.1007/s10802-014-9906-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284153PMC
February 2015

Executive function moderates the relation between coping and depressive symptoms.

Anxiety Stress Coping 2015 17;28(1):31-49. Epub 2014 Jun 17.

a Department of Family and Community Medicine , Meharry Medical College , Nashville , TN , USA.

Background And Objectives: Identifying risk factors early in the course of depression has important implications for prevention, given that the likelihood of recurrence increases with each successive episode.

Design: This study examined relations among coping, executive functioning, and depressive symptom trajectories in a sample of remitted-depressed (n = 32) and never-depressed (ND; n = 36) young adults (aged 18-31).

Methods: Participants completed a clinical interview, a measure of coping, and tasks assessing two components of executive function - inhibition and cognitive flexibility. Participants were reassessed regarding the timing and severity of depressive symptoms that had occurred during the interval period (mean = 35.16 weeks, SD = 9.03).

Results: Among ND individuals, less primary control coping (e.g., problem-solving) and greater disengagement coping (e.g., avoidance) predicted increases in depressive symptoms. Greater secondary control coping (e.g., acceptance) predicted decreases in depressive symptoms and was unrelated to depression history. Higher inhibition scores predicted less increase in depressive symptoms for individuals reporting less primary control coping or more disengagement coping. Higher cognitive flexibility scores predicted less increase in depressive symptoms among individuals reporting less secondary control coping.

Conclusions: Interventions aiming to enhance either coping strategies or executive functions may reduce risk of depression recurrence.
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http://dx.doi.org/10.1080/10615806.2014.925545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236259PMC
July 2015

A simplified methodology for identifying the function of elopement.

J Appl Behav Anal 2013 20;46(1):256-70. Epub 2013 Feb 20.

University of Houston-Clear Lake.

Functional analyses of elopement (i.e., leaving a specific area without permission) are challenging to conduct because clients must have repeated opportunities to elope from one room (or area) to another safely. These analyses often require two or more adjoining rooms and retrieval of the client following each instance of elopement (e.g., Piazza et al., 1997). These room arrangements may be impractical in some settings, and therapist delivery of attention or demands during retrieval may confound the results. To address these issues, we evaluated the viability of conducting a functional analysis (FA) of elopement within a single room. Participants were 2 children and 2 adults with developmental disabilities who eloped from rooms at their day programs. Results of the single-room assessments were compared to those of a second FA that was conducted using methods similar to those described in previous studies. Function-based treatments were implemented for each participant. Results suggest that the single-room assessment may be a viable alternative for identifying the function of elopement.
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http://dx.doi.org/10.1002/jaba.22DOI Listing
May 2014

N-N bond-forming cyclization for the one-pot synthesis of N-aryl[3,4-d]pyrazolopyrimidines.

Org Lett 2012 Jul 26;14(13):3546-9. Epub 2012 Jun 26.

Division of Cancer Therapeutics, The Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, UK.

An efficient one-pot synthesis of N-aryl[3,4-d]pyrazolopyrimidines in good yield and under mild reaction conditions is described. By exploiting electron-deficient hydroxylamines, the substituted oxime products were formed with very high E-diastereoselectivity. The key step utilizes a cyclization reaction upon an oxime derived from hydroxylamine-O-sulfonic acid to form the N-N bond of the product.
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http://dx.doi.org/10.1021/ol301561aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3390909PMC
July 2012

Ovarian hormones are not required for PRL-induced mammary tumorigenesis, but estrogen enhances neoplastic processes.

J Endocrinol 2009 Oct 27;203(1):99-110. Epub 2009 Jul 27.

Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.

Epidemiologic studies have demonstrated that increased prolactin (PRL) exposure raises the risk of invasive estrogen receptor alpha (ERalpha)-positive breast cancer in women. However, the mechanism(s) whereby this occurs and the interactions with estrogen itself in this disease remain poorly understood. In order to investigate the role of ovarian hormones in the disease process, we employed a transgenic model neu-related lipocalin (NRL)-PRL in which transgenic PRL is directed to mammary epithelial cells by the PRL- and estrogen-insensitive NRL promoter, mimicking the endogenous PRL expression within the breast observed in women. This high local exposure leads to mammary lesion development and eventually carcinomas. Ovariectomy (ovx), shortly after puberty, did not alter the incidence or latency of PRL-induced mammary carcinomas, consistent with the independence of PRL from circulating estrogens as a risk factor for invasive breast cancer in women. However, chronic estrogen administration to ovx NRL-PRL females decreased the latency of both ERalpha-positive and -negative tumors. We identified multiple mechanisms that may underlie this observation. Elevated estrogen exposure cooperated with PRL to increase epithelial proliferation and myoepithelial abnormalities, increasing the incidence of preneoplastic lesions. Critical components of the extracellular matrix secreted by the myoepithelium were reduced with age, and transgenic PRL raised transcripts for tenascin-C and maspin, both associated with tumor progression and poor prognosis in subclasses of clinical breast tumors. Mammary pERK1/2 and pAkt, but not phosphorylated Stat5, were markedly elevated by local PRL. Together, these findings indicate that PRL employs multiple mechanisms to promote mammary tumorigenesis.
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http://dx.doi.org/10.1677/JOE-09-0221DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841967PMC
October 2009

Regulatory and legislative attempts at limiting medical resident work hours.

Authors:
Lindsay Evans

J Leg Med 2002 Jun;23(2):251-67

Southern Illinois University School of Law, Illinois 62901, USA.

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http://dx.doi.org/10.1080/01947640252987312DOI Listing
June 2002
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