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Found 35934 matches. Displaying 91-100
Marchildon F, Chi JY, O'Connor S, Bediako H, Cohen P
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Beige fat is dispensable for the metabolic benefits associated with myostatin deletion

MOLECULAR METABOLISM 2021 JAN; 43(?):? Article 101120
Objective: Increasing muscle mass and activating beige fat both have great potential for ameliorating obesity and its comorbidities. Myostatin null mice have increased skeletal muscle mass and are protected from obesity and its sequelae. Deletion of myostatin has also been suggested to result in the activation of beige adipocytes, thermogenic fat cells with anti-obesity and anti-diabetes properties. It is not known whether beige fat activation contributes to the protection from obesity in myostatin null mice. Methods: To investigate the role of beige fat activation in the metabolic benefits associated with myostatin deletion, we crossed myostatin null mice to adipocyte-specific PRDM16 knockout mice. We analyzed this new mouse model using molecular profiling, whole mount threedimensional tissue imaging, tissue respiration, and glucose and insulin tolerance tests in models of diet-induced obesity. Results: Here, we report that PRDM16 is required for the activation of beige fat in the absence of myostatin. However, we show in both male and female mice that beige fat activation is dispensable for the protection from obesity, glucose intolerance, insulin resistance, and hepatic steatosis mediated by myostatin deletion. Conclusion: These findings demonstrate that increasing muscle mass can compensate for the inactivation of beige fat and raise the possibility of targeting muscle mass as a therapeutic approach to offset the deleterious effects of adipose tissue dysfunction in obesity and metabolic syndrome. (C) 2020 The Authors. Published by Elsevier GmbH.
Olesen CM, Pavel AB, Wu JN, Mikhaylov D, Del Duca E, Estrada Y, Krueger JG, Zhang N, Clausen ML, Agner T, Guttman-Yassky E
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Tape-strips provide a minimally invasive approach to track therapeutic response to topical corticosteroids in atopic dermatitis patients

Bruno JH, Jarvis ED, Liberman M, Tchernichovski O
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Birdsong Learning and Culture: Analogies with Human Spoken Language

Unlike many species, song learning birds and humans have independently evolved the ability to communicate via learned vocalizations. Both birdsong and spoken language are culturally transmitted across generations, within species-specific constraints that leave room for considerable variation. We review the commonalities and differences between vocal learning bird species and humans, across behavioral, developmental, neuroanatomical, physiological, and genetic levels. We propose that cultural transmission of vocal repertoires is a natural consequence of the evolution of vocal learning and that at least some species-specific universals, as well as species differences in cultural transmission, are due to differences in vocal learning phenotypes, which are shaped by genetic constraints. We suggest that it is the balance between these constraints and features of the social environment that allows cultural learning to propagate. We describe new opportunities for exploring meaningful comparisons of birdsong and human vocal culture.
Hakhverdyan Z, Molloy KR, Keegan S, Herricks T, Lepore DM, Munson M, Subbotin RI, Fenyo D, Aitchison JD, Fernandez-Martinez J, Chait BT, Rout MP
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Dissecting the Structural Dynamics of the Nuclear Pore Complex

MOLECULAR CELL 2021 JAN 7; 81(1):153-165.e7
Cellular processes are largely carried out by macromolecular assemblies, most of which are dynamic, having components that are in constant flux. One such assembly is the nuclear pore complex (NPC), an similar to 50 MDa assembly comprised of similar to 30 different proteins called Nups that mediates selective macromolecular transport between the nucleus and cytoplasm. We developed a proteomics method to provide a comprehensive picture of the yeast NPC component dynamics. We discovered that, although all Nups display uniformly slow turnover, their exchange rates vary considerably. Surprisingly, this exchange rate was relatively unrelated to each Nup's position, accessibility, or role in transport but correlated with its structural role; scaffold-forming Nups exchange slowly, whereas flexible connector Nups threading throughout the NPC architecture exchange more rapidly. Targeted perturbations in the NPC structure revealed a dynamic resilience to damage. Our approach opens a new window into macromolecular assembly dynamics.
Freedenberg AT, Pan CH, Diehl WE, Romeiser JL, Hwang GR, Leiton CV, Muecksch F, Shroyer KR, Bennett-Guerrero E
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Neutralizing activity to SARS-CoV-2 of convalescent and control plasma used in a randomized controlled trial

TRANSFUSION 2021; ?(?):?
Background There are limited data on the neutralizing activity of convalescent plasma (CP) administered in randomized controlled trials (RCT) of COVID-19 infection. Study Design and Methods As part of an RCT, CP was collected per FDA guidelines from individuals recovered from COVID-19 infection. CP donors had to have >= 145 optical density (OD) units (ideal target >= 300) using a semiquantitative, immunochromatographic test for IgG antibody to the nucleocapsid protein (NP) of SARS-CoV-2 (typical range 0-500 OD units). A random subset of samples [14 control plasma, 12 CP "medium-anti-NP" (145-299 OD units), and 13 CP "high" anti-NP (>= 300 OD units)] were tested for neutralizing antibodies using an established viral luciferase antibody inhibition assay to detect the infection of SARS-CoV-2 pseudovirus that encoded spike protein (SARS2-S-trunc) on a human immunodeficiency virus 1 vector (NL43dEnvNanoLuc), using ACE2-expressing 293 T cells. The titer needed to neutralize 50% of viral activity (NT50) was calculated. Results The uptake of SARS-CoV-2 pseudovirus by 293T(ACE2) cells was inhibited by pretreatment with CP compared to control CP (p < .001) with control plasma having a median (IQR) 50% neutralization titer (NT50) of 1:28 (1:16,1:36) compared to 1:334 (1:130,1:1295) and 1:324 (1:244,1:578), for medium anti-NP and high anti-NP CP units, respectively. The neutralizing activity of CP met minimum FDA criteria with neutralizing antibody titers >1:80 in 100% of randomly selected samples, using a conservative approach that excluded non-specific binding. Discussion Plasma from donors screened using an immunochromatographic test for IgG antibody to SARS-CoV-2 NP exhibited neutralizing activity meeting FDA's minimum standard in all randomly selected COVID-19 CP units.
Kennel PJ, Yahi A, Naka Y, Mancini DM, Marboe CC, Max K, Akat K, Tuschl T, Vasilescu ERM, Zorn E, Tatonetti NP, Schulze PC
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Longitudinal profiling of circulating miRNA during cardiac allograft rejection: a proof-of-concept study

ESC HEART FAILURE 2021; ?(?):?
Aims Allograft rejection following heart transplantation (HTx) is a serious complication even in the era of modern immunosuppressive regimens and causes up to a third of early deaths after HTx. Allograft rejection is mediated by a cascade of immune mechanisms leading to acute cellular rejection (ACR) and/or antibody-mediated rejection (AMR). The gold standard for monitoring allograft rejection is invasive endomyocardial biopsy that exposes patients to complications. Little is known about the potential of circulating miRNAs as biomarkers to detect cardiac allograft rejection. We here present a systematic analysis of circulating miRNAs as biomarkers and predictors for allograft rejection after HTx using next-generation small RNA sequencing. Methods and results We used next-generation small RNA sequencing to investigate circulating miRNAs among HTx recipients (10 healthy controls, 10 heart failure patients, 13 ACR, and 10 AMR). MiRNA profiling was performed at different time points before, during, and after resolution of the rejection episode. We found three miRNAs with significantly increased serum levels in patients with biopsy-proven cardiac rejection when compared with patients without rejection: hsa-miR-139-5p, hsa-miR-151a-5p, and hsa-miR-186-5p. We identified miRNAs that may serve as potential predictors for the subsequent development of ACR: hsa-miR-29c-3p (ACR) and hsa-miR-486-5p (AMR). Overall, hsa-miR-486-5p was most strongly associated with acute rejection episodes. Conclusions Monitoring cardiac allograft rejection using circulating miRNAs might represent an alternative strategy to invasive endomyocardial biopsy.
Karayol R, Medrihan L, Warner-Schmidt JL, Fait BW, Rao MN, Holzner EB, Greengard P, Heintz N, Schmidt EF
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Serotonin receptor 4 in the hippocampus modulates mood and anxiety

Serotonin receptor 4 (5-HT4R) plays an important role in regulating mood, anxiety, and cognition, and drugs that activate this receptor have fast-acting antidepressant (AD)-like effects in preclinical models. However, 5-HT4R is widely expressed throughout the central nervous system (CNS) and periphery, making it difficult to pinpoint the cell types and circuits underlying its effects. Therefore, we generated a Cre-dependent 5-HT4R knockout mouse line to dissect the function of 5-HT4R in specific brain regions and cell types. We show that the loss of functional 5-HT4R specifically from excitatory neurons of hippocampus led to robust AD-like behavioral responses and an elevation in baseline anxiety. 5-HT4R was necessary to maintain the proper excitability of dentate gyrus (DG) granule cells and cell type-specific molecular profiling revealed a dysregulation of genes necessary for normal neural function and plasticity in cells lacking 5-HT4R. These adaptations were accompanied by an increase in the number of immature neurons in ventral, but not dorsal, dentate gyrus, indicating a broad impact of 5-HT4R loss on the local cellular environment. This study is the first to use conditional genetic targeting to demonstrate a direct role for hippocampal 5-HT4R signaling in modulating mood and anxiety. Our findings also underscore the need for cell type-based approaches to elucidate the complex action of neuromodulatory systems on distinct neural circuits.
Hoffmann HH, Schneider WM, Rozen-Gagnon K, Miles LA, Schuster F, Razooky B, Jacobson E, Wu XF, Yi S, Rudin CM, MacDonald MR, McMullan LK, Poirier JT, Rice CM
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TMEM41B Is a Pan-flavivirus Host Factor

CELL 2021 JAN 7; 184(1):133-148.e20
Flaviviruses pose a constant threat to human health. These RNA viruses are transmitted by the bite of infected mosquitoes and ticks and regularly cause outbreaks. To identify host factors required for flavivirus infection, we performed full-genome loss of function CRISPR-Cas9 screens. Based on these results, we focused our efforts on characterizing the roles that TMEM41B and VMP1 play in the virus replication cycle. Our mechanistic studies on TMEM41B revealed that all members of the Flaviviridae family that we tested require TMEM41B. We tested 12 additional virus families and found that SARS-CoV-2 of the Coronaviridae also required TMEM41B for infection. Remarkably, single nucleotide polymorphisms present at nearly 20% in East Asian populations reduce flavivirus infection. Based on our mechanistic studies, we propose that TMEM41B is recruited to flavivirus RNA replication complexes to facilitate membrane curvature, which creates a protected environment for viral genome replication.
Merkenschlager J, Finkin S, Ramos V, Kraft J, Cipolla M, Nowosad CR, Hartweger H, Zhang WZ, Olinares PDB, Gazumyan A, Oliveira TY, Chait BT, Nussenzweig MC
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Dynamic regulation of T-FH selection during the germinal centre reaction

NATURE 2021; 591(?):458-463
The germinal centre is a dynamic microenvironment in which B cells that express high-affinity antibody variants produced by somatic hypermutation are selected for clonal expansion by limiting the numbers of T follicular helper cells(1,2). Although much is known about the mechanisms that control the selection of B cells in the germinal centre, far less is understood about the clonal behaviour of the T follicular helper cells that help to regulate this process. Here we report on the dynamic behaviour of T follicular helper cell clones during the germinal centre reaction. We find that, similar to germinal centre B cells, T follicular helper cells undergo antigen-dependent selection throughout the germinal centre reaction that results in differential proliferative expansion and contraction. Increasing the amount of antigen presented in the germinal centre leads to increased division of T follicular helper cells. Competition between T follicular helper cell clones is mediated by the affinity of T cell receptors for peptide-major-histocompatibility-complex ligands. T cells that preferentially expand in the germinal centre show increased expression of genes downstream of the T cell receptor, such as those required for metabolic reprogramming, cell division and cytokine production. These dynamic changes lead to marked remodelling of the functional T follicular helper cell repertoire during the germinal centre reaction.
Santich BH, Cheal SM, Ahmed M, McDevitt MR, Ouerfelli O, Yang GB, Veach DR, Fung EK, Patel M, Vargas DB, Malik AA, Guo HF, Zanzonico PB, Monette S, Michel AO, Rudin CM, Larson SM, Cheung NK
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A Self-Assembling and Disassembling (SADA) Bispecific Antibody (BsAb) Platform for Curative Two-step Pretargeted Radioimmunotherapy

CLINICAL CANCER RESEARCH 2021 JAN 15; 27(2):532-541
Purpose: Many cancer treatments suffer from dose-limiting toxicities to vital organs due to poor therapeutic indices. To overcome these challenges we developed a novel multimerization platform that rapidly removes tumor-targeting proteins from the blood to substantially improve therapeutic index. Experimental Design: The platform was designed as a fusion of a self-assembling and disassembling (SADA) domain to a tandem single-chain bispecific antibody (BsAb, anti-gangliosideGD2 x anti-DOTA). SADA-BsAbs were assessed with multiple in vivo tumor models using two-step pretargeted radioimmunotherapy (PRIT) to evaluate tumor uptake, dosimetry, and antitumor responses. Results: SADA-BsAbs self-assembled into stable tetramers (220 kDa), but could also disassemble into dimers or monomers (55 kDa) that rapidly cleared via renal filtration and substantially reduced immunogenicity in mice. When used with rapidly clearing DOTA-caged PET isotopes, SADA-BsAbs demonstrated accurate tumor localization, dosimetry, and improved imaging contrast by PET/CT. When combined with therapeutic isotopes, two-step SADA-PRIT safely delivered massive doses of alpha-emitting (Ac-225, 1.48 MBq/kg) or beta-emitting (Lu-177, 6,660 MBq/kg) S-2-(4-aminobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid (DOTA) payloads to tumors, ablating them without any short-term or long-term toxicities to the bone marrow, kidneys, or liver. Conclusions: The SADA-BsAb platform safely delivered large doses of radioisotopes to tumors and demonstrated no toxicities to the bone marrow, kidneys, or liver. Because of its modularity, SADA-BsAbs can be easily adapted to most tumor antigens, tumor types, or drug delivery approaches to improve therapeutic index and maximize the delivered dose.