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Found 35934 matches. Displaying 31-40
Wang YD, Niu YM, Zhang Z, Gable K, Gupta SD, Somashekarappa N, Han GS, Zhao HT, Myasnikov AG, Kalathur RC, Dunn TM, Lee CH
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Structural insights into the regulation of human serine palmitoyltransferase complexes

Cryo-EM structures of the enzyme complexes catalyzing the rate-limiting step in sphingolipid synthesis reveal mechanisms of substrate recognition and modulation by regulatory subunits. Sphingolipids are essential lipids in eukaryotic membranes. In humans, the first and rate-limiting step of sphingolipid synthesis is catalyzed by the serine palmitoyltransferase holocomplex, which consists of catalytic components (SPTLC1 and SPTLC2) and regulatory components (ssSPTa and ORMDL3). However, the assembly, substrate processing and regulation of the complex are unclear. Here, we present 8 cryo-electron microscopy structures of the human serine palmitoyltransferase holocomplex in various functional states at resolutions of 2.6-3.4 angstrom. The structures reveal not only how catalytic components recognize the substrate, but also how regulatory components modulate the substrate-binding tunnel to control enzyme activity: ssSPTa engages SPTLC2 and shapes the tunnel to determine substrate specificity. ORMDL3 blocks the tunnel and competes with substrate binding through its amino terminus. These findings provide mechanistic insights into sphingolipid biogenesis governed by the serine palmitoyltransferase complex.
Coscia EC, Abutaleb NS, Hostetter B, Seleem MN, Breur GJ, McCain RR, Crain CJ, Slaby O, Capoor MN, McDowell A, Ahmed FS, Vijayanpillai V, Narayanan SK, Coscia MF
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Sheep as a Potential Model of Intradiscal Infection by the Bacterium Cutibacterium acnes

VETERINARY SCIENCES 2021 MAR; 8(3):? Article 48
The anaerobic bacterium Cutibacterium acnes has been increasingly linked to the development of degenerative disc disease (DDD), although causality is yet to be conclusively proven. To better study how this organism could contribute to the aetiology of DDD, improved animal models that are more reflective of human disc anatomy, biology and mechanical properties are required. Against this background, our proof-of concept study aimed to be the first demonstration that C. acnes could be safely administered percutaneously into sheep intervertebral discs (IVDs) for in vivo study. Following our protocol, two sheep were successfully injected with a strain of C. acnes (8.3 x 10(6) CFU/disc) previously recovered from a human degenerative disc. No adverse reactions were noted, and at one-month post inoculation all triplicate infected discs in our first animal grew C. acnes, albeit at a reduced load (5.12 x 10(4) to 6.67 x 10(4) CFU/disc). At six months, no growth was detected in discs from our second animal indicating bacterial clearance. This pilot study has demonstrated the feasibility of safe percutaneous injection of C. acnes into sheep IVDs under fluoroscopic guidance. The design of follow-up sheep studies to investigate the potential of C. acnes to drive pathological changes within infected discs should now be pursued.
Hitchman TD, Bayshtok G, Ceraudo E, Moore AR, Lee C, Jia RB, Wang NT, Pachai MR, Shoushtari AN, Francis JH, Guan YX, Chen J, Chang MT, Taylor BS, Sakmar TP, Huber T, Chi P, Chen Y
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Combined Inhibition of G alpha(q) and MEK Enhances Therapeutic Efficacy in Uveal Melanoma

CLINICAL CANCER RESEARCH 2021 MAR 1; 27(5):1476-1490
Purpose: All uveal melanoma and a fraction of other melanoma subtypes are driven by activation of the G-protein alpha-q (G alpha(q)) pathway. Targeting these melanomas has proven difficult despite advances in the molecular understanding of key driver signaling pathways in the disease pathogenesis. Inhibitors of G alpha(q) have shown promising preclinical results, but their therapeutic activity in distinct G alpha(q) mutational contexts and in vivo have remained elusive. Experimental Design: We used an isogenic melanocytic cellular system to systematically examine hotspot mutations in GNAQ (e.g., G48V, R183Q, Q209L) and CYSLTR2 (L129Q) found in human uveal melanoma. This cellular system and human uveal melanoma cell lines were used in vitro and in in vivo xenograft studies to assess the efficacy of G alpha(q) inhibition as a single agent and in combination with MEK inhibition. Results: We demonstrate that the G alpha(q) inhibitor YM-254890 inhibited downstream signaling and in vitro growth in all mutants. In vivo, YM-254890 slowed tumor growth but did not cause regression in human uveal melanoma xenografts. Through comprehensive transcriptome analysis, we observed that YM-254890 caused inhibition of the MAPK signaling with evidence of rebound by 24 hours and combination treatment of YM-254890 and a MEK inhibitor led to sustained MAPK inhibition. We further demonstrated that the combination caused synergistic growth inhibition in vitro and tumor shrinkage in vivo. Conclusions: These data suggest that the combination of G alpha(q) and MEK inhibition provides a promising therapeutic strategy and improved therapeutic window of broadly targeting G alpha(q) in uveal melanoma. See related commentary by Neelature Sriramareddy and Smalley, p. 1217
Mann N, Mzoughi S, Schneider R, Kuhl SJ, Schanze D, Klambt V, Lovric S, Mao YY, Shi SS, Tan WZ, Kuhl M, Onuchic-Whitford AC, Treimer E, Kitzler TM, Kause F, Schumann S, Nakayama M, Buerger F, Shril S, van der Ven AT, Majmundar AJ, Holton KM, Kolb A, Braun DA, Rao J, Jobst-Schwan T, Mildenberger E, Lennert T, Kuechler A, Wieczorek D, Gross O, Ermisch-Omran B, Werberger A, Skalej M, Janecke AR, Soliman NA, Mane SM, Lifton RP, Kadlec J, Guccione E, Schmeisser MJ, Zenker M, Hildebrandt F
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Mutations in PRDM15 Are a Novel Cause of Galloway-Mowat Syndrome

Background Galloway-Mowat syndrome (GAMOS) is characterized by neurodevelopmental defects and a progressive nephropathy, which typically manifests as steroid-resistant nephrotic syndrome. The prognosis of GAMOS is poor, and the majority of children progress to renal failure. The discovery of monogenic causes of GAMOS has uncovered molecular pathways involved in the pathogenesis of disease. Methods Homozygosity mapping, whole-exome sequencing, and linkage analysis were used to identify mutations in four families with a GAMOS-like phenotype, and high-throughput PCR technology was applied to 91 individuals with GAMOS and 816 individuals with isolated nephrotic syndrome. In vitro and in vivo studies determined the functional significance of the mutations identified. Results Three biallelic variants of the transcriptional regulator PRDM15 were detected in six families with proteinuric kidney disease. Four families with a variant in the protein's zinc-finger (ZNF) domain have additional GAMOS-like features, including brain anomalies, cardiac defects, and skeletal defects. All variants destabilize the PRDM15 protein, and the ZNF variant additionally interferes with transcriptional activation. Morpholino oligonucleotide-mediated knockdown of Prdm15 in Xenopus embryos disrupted pronephric development. Human wild-type PRDM15 RNA rescued the disruption, but the three PRDM15 variants did not. Finally, CRISPR-mediated knockout of PRDM15 in human podocytes led to dysregulation of several renal developmental genes. Conclusions Variants in PRDM15 can cause either isolated nephrotic syndrome or a GAMOS-type syndrome on an allelic basis. PRDM15 regulates multiple developmental kidney genes, and is likely to play an essential role in renal development in humans.
Frew JW, Marzano AV, Wolk K, Join-Lambert O, Alavi A, Lowes MA, Piguet V
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A Systematic Review of Promising Therapeutic Targets in Hidradenitis Suppurativa: A Critical Evaluation of Mechanistic and Clinical Relevance

This systematic review identifies and critically evaluates the mechanistic and clinical evidence of new promising therapeutic targets in hidradenitis suppurativa (HS). Evidence for these targets is largely based on observational data with limited ex vivo and translational data from clinical trials. A number of placebo-controlled studies have been completed or are underway utilizing IL-1, IL-23, IL-17, complement, and Jak inhibition, although there is concern regarding elevated placebo response rates and the questionable validity of clinical scores in some participant subsets. Knowledge gaps are identified suggesting a direction for future mechanistic studies in HS, including more comprehensive inflammatory endotype profiling of disease.
Moura-Assis A, Friedman JM, Velloso LA
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Gut-to-brain signals in feeding control

Interoceptive signals from gut and adipose tissue and sensory cues from the environment are integrated by hubs in the brain to regulate feeding behavior and maintain homeostatic control of body weight. In vivo neural recordings have revealed that these signals control the activity of multiple layers of hunger neurons and eating is not only the result of feedback correction to a set point, but can also be under the influence of anticipatory regulations. A series of recent technical developments have revealed how peripheral and sensory signals, in particular, from the gut are conveyed to the brain to integrate neural circuits. Here, we describe the mechanisms involved in gastrointestinal stimulation by nutrients and how these signals act on the hindbrain to generate motivated behaviors. We also consider the organization of multidirectional intra- and extrahypothalamic circuits and how this has created a framework for understanding neural control of feeding.
Boyce WT, Levitt P, Martinez FD, McEwen BS, Shonkoff JP
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Genes, Environments, and Time: The Biology of Adversity and Resilience

PEDIATRICS 2021 FEB; 147(2):? Article e20201651
Exposures to adverse environments, both psychosocial and physicochemical, are prevalent and consequential across a broad range of childhood populations. Such adversity, especially early in life, conveys measurable risk to learning and behavior and to the foundations of both mental and physical health. Using an interactive gene-environment-time (GET) framework, we survey the independent and interactive roles of genetic variation, environmental context, and developmental timing in light of advances in the biology of adversity and resilience, as well as new discoveries in biomedical research. Drawing on this rich evidence base, we identify 4 core concepts that provide a powerful catalyst for fresh thinking about primary health care for young children: (1) all biological systems are inextricably integrated, continuously "reading" and adapting to the environment and "talking back" to the brain and each other through highly regulated channels of cross-system communication; (2) adverse environmental exposures induce alterations in developmental trajectories that can lead to persistent disruptions of organ function and structure; (3) children vary in their sensitivity to context, and this variation is influenced by interactions among genetic factors, family and community environments, and developmental timing; and (4) critical or sensitive periods provide unmatched windows of opportunity for both positive and negative influences on multiple biological systems. These rapidly moving frontiers of investigation provide a powerful framework for new, science-informed thinking about health promotion and disease prevention in the early childhood period. Advances in biology provide a platform for fresh thinking about health promotion and disease prevention in the early childhood period.
Gordon KB, Foley P, Krueger JG, Pinter A, Reich K, Vender R, Vanvoorden V, Madden C, White K, Cioffi C, Blauvelt A
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Bimekizumab efficacy and safety in moderate to severe plaque psoriasis (BE READY): a multicentre, double-blind, placebo-controlled, randomised withdrawal phase 3 trial

LANCET 2021 FEB 6; 397(10273):475-486
Background Bimekizumab is a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A. This study investigated the efficacy and safety of bimekizumab in patients with moderate to severe plaque psoriasis, the effects of treatment withdrawal, and two maintenance dosing schedules over 56 weeks. Methods BE READY was a phase 3, multicentre, randomised, double-blind, placebo-controlled trial done at 77 sites (hospitals, clinics, private doctor's practices, and dedicated clinical research centres) in nine countries across Asia, Australia, Europe, and North America. Adult patients aged 18 years or older with moderate to severe plaque psoriasis were stratified by region and previous biologic exposure, and randomly assigned (4:1) to receive bimekizumab 320 mg every 4 weeks or placebo every 4 weeks by use of interactive response technology. Coprimary endpoints were the proportion of patients achieving 90% or greater improvement from baseline in the Psoriasis Area Severity Index (PASI90) and the proportion of patients achieving a score of 0 (clear) or 1 (almost clear) on the five-point Investigator's Global Assessment (IGA) scale at week 16 (non-responder imputation). Bimekizumab-treated patients achieving PASI90 at week 16 were re-allocated (1:1:1) to receive bimekizumab 320 mg every 4 weeks, every 8 weeks, or placebo for weeks 16-56. Efficacy analyses were done in the intention-to-treat population; the safety analysis set comprised all patients who received at least one dose of study treatment. This trial is registered with (NCT03410992), and is now completed. Findings Between Feb 5, 2018, and Jan 7, 2020, 435 patients were randomly assigned to receive either bimekizumab 320 mg every 4 weeks (n=349) or placebo every 4 weeks (n=86). Coprimary endpoints were met: at week 16, 317 (91%) of 349 patients receiving bimekizumab 320 mg every 4 weeks achieved PASI90, compared with one (1%) of 86 patients receiving placebo (risk difference 89.8 [95% CI 86.1-93.4]; p<0.0001); and 323 (93%) of 349 patients receiving bimekizumab 320 mg every 4 weeks achieved an IGA score of 0 or 1 versus one (1%) of 86 patients receiving placebo (risk difference 91.5 [95% CI 88.0-94.9]; p<0.0001). Responses were maintained through to week 56 with bimekizumab 320 mg every 8 weeks and every 4 weeks. Treatment-emergent adverse events in the initial treatment period (up to week 16) were reported in 213 (61%) of 349 patients receiving bimekizumab 320 mg every 4 weeks and 35 (41%) of 86 patients receiving placebo every 4 weeks. From week 16 to week 56, treatment-emergent adverse events were reported in 78 (74%) of 106 patients receiving bimekizumab 320 mg every 4 weeks, 77 (77%) of 100 patients receiving bimekizumab 320 mg every 8 weeks, and 72 (69%) of 105 patients receiving placebo. Interpretation Bimekizumab showed high levels of response, which were durable over 56 weeks, with both maintenance dosing schedules (every 4 weeks and every 8 weeks). Moreover, bimekizumab was well tolerated, with no unexpected safety findings. Data presented here further support the therapeutic value of bimekizumab and inhibition of IL-17F in addition to IL-17A for patients with moderate to severe plaque psoriasis.
La Fleur L, Botling J, He F, Pelicano C, Zhou CK, He CF, Palano G, Mezheyeuski A, Micke P, Ravetch JV, Karlsson MCI, Sarhan D
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Targeting MARCO and IL37R on Immunosuppressive Macrophages in Lung Cancer Blocks Regulatory T Cells and Supports Cytotoxic Lymphocyte Function

CANCER RESEARCH 2021 FEB 15; 81(4):956-967
The progression and metastatic capacity of solid tumors are strongly influenced by immune cells in the tumor microenvironment. In non-small cell lung cancer (NSCLC), accumulation of anti-inflammatory tumor-associated macrophages (TAM) is associated with worse clinical outcome and resistance to therapy. Here we investigated the immune landscape of NSCLC in the presence of protumoral TAMs expressing the macrophage receptor with collagenous structure (MARCO). MARCO-expressing TAM numbers correlated with increased occurrence of regulatory T cells and effector T cells and decreased natural killer (NK) cells in these tumors. Furthermore, transcriptomic data from the tumors uncovered a correlation between MARCO expression and the antiinflammatory cytokine IL37. In vitro studies subsequently showed that lung cancer cells polarized macrophages to express MARCO and gain an immune-suppressive phenotype through the release of IL37. MARCO-expressing TAMs blocked cytotoxic T-cell and NK-cell activation, inhibiting their proliferation, cytokine production, and tumor killing capacity. Mechanistically, MARCO(+) macrophages enhanced regulatory T (Treg) cell proliferation and IL10 production and diminished CD8 T-cell activities. Targeting MARCO or IL37 receptor (IL37R) by antibody or CRISPR knockout of IL37 in lung cancer cell lines repolarized TAMs, resulting in recovered cytolytic activity and antitumoral capacity of NK cells and T cells and down-modulated Treg cell activities. In summary, our data demonstrate a novel immune therapeutic approach targeting human TAMs immune suppression of NK- and T-cell antitumor activities. Significance: This study defines tumor-derived IL37 and the macrophage scavenger receptor MARCO as potential therapeutic targets to remodel the immune-suppressive microenvimnment in patients with lung cancer.
Rostol JT, Xie W, Kuryavyi V, Maguin P, Kao K, Froom R, Patel DJ, Marraffini LA
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The Card1 nuclease provides defence during type III CRISPR immunity

NATURE 2021 FEB 25; 590(7847):?
In the type III CRISPR-Cas immune response of prokaryotes, infection triggers the production of cyclic oligoadenylates that bind and activate proteins that contain a CARF domain(1,2). Many type III loci are associated with proteins in which the CRISPR-associated Rossman fold (CARF) domain is fused to a restriction endonuclease-like domain(3,4). However, with the exception of the well-characterized Csm6 and Csx1 ribonucleases(5,6), whether and how these inducible effectors provide defence is not known. Here we investigated a type III CRISPR accessory protein, which we name cyclic-oligoadenylate-activated single-stranded ribonuclease and single-stranded deoxyribonuclease 1 (Card1). Card1 forms a symmetrical dimer that has a large central cavity between its CRISPR-associated Rossmann fold and restriction endonuclease domains that binds cyclic tetra-adenylate. The binding of ligand results in a conformational change comprising the rotation of individual monomers relative to each other to form a more compact dimeric scaffold, in which a manganese cation coordinates the catalytic residues and activates the cleavage of single-stranded-but not double-stranded-nucleic acids (both DNA and RNA). In vivo, activation of Card1 induces dormancy of the infected hosts to provide immunity against phage infection and plasmids. Our results highlight the diversity of strategies used in CRISPR systems to provide immunity. Structural analyses of the type III CRISPR accessory protein Card1, which induces dormancy in infected hosts to provide immunity against phage infection, reveal the mechanisms by which it cleaves single-stranded RNA and DNA.