se Proteome analysis reveals a significant host-specific response in Rhizobium leguminosarum bv viciae endosymbiotic cells By www.mcponline.org Published On :: 2020-11-19 David DuránNov 19, 2020; 0:RA120.002276v1-mcp.RA120.002276Research Full Article
se A proteomics-based assessment of inflammation signatures in endotoxemia By www.mcponline.org Published On :: 2020-12-07 Sean A BurnapDec 7, 2020; 0:RA120.002305v1-mcp.RA120.002305Research Full Article
se Quantitative proteomics reveal neuron projection development genes ARF4, KIF5B and RAB8A associated with Hirschsprung disease By www.mcponline.org Published On :: 2020-11-17 Qin ZhangNov 17, 2020; 0:RA120.002325v1-mcp.RA120.002325Research Full Article
se Proteomic analyses identify differentially expressed proteins and pathways between low-risk and high-risk subtypes of early-stage lung adenocarcinoma and their prognostic impacts By www.mcponline.org Published On :: 2020-11-30 Juntuo ZhouNov 30, 2020; 0:RA120.002384v1-mcp.RA120.002384Research Full Article
se A proteomic approach to understand the clinical significance of acute myeloid leukemia-derived extracellular vesicles reflecting essential characteristics of leukemia By www.mcponline.org Published On :: 2020-11-30 Ka-Won KangNov 30, 2020; 0:RA120.002169v1-mcp.RA120.002169Research Full Article
se Prediction and validation of mouse meiosis-essential genes based on spermatogenesis proteome dynamics By www.mcponline.org Published On :: 2020-11-30 Kailun FangNov 30, 2020; 0:RA120.002081v1-mcp.RA120.002081Research Full Article
se The Mechanism of NEDD8 Activation of CUL5 Ubiquitin E3 Ligases By www.mcponline.org Published On :: 2020-12-02 Ryan J LumpkinDec 2, 2020; 0:RA120.002414v1-mcp.RA120.002414Research Full Article
se Peptidomics-driven strategy reveals peptides and predicted proteases associated with oral cancer prognosis By www.mcponline.org Published On :: 2020-11-11 Leandro Xavier NevesNov 11, 2020; 0:RA120.002227v1-mcp.RA120.002227Research Full Article
se Spatially Resolved Activity-based Proteomic Profiles of the Murine Small Intestinal Lipases By www.mcponline.org Published On :: 2020-12-01 Matthias SchittmayerDec 1, 2020; 19:2104-2114Research Full Article
se Accelerating the field of epigenetic histone modification through mass spectrometry-based approaches By www.mcponline.org Published On :: 2020-11-17 Congcong LuNov 17, 2020; 0:R120.002257v1-mcp.R120.002257Review Full Article
se PTM-Shepherd: analysis and summarization of post-translational and chemical modifications from open search results By www.mcponline.org Published On :: 2020-12-01 Daniel J. GeiszlerDec 1, 2020; 0:TIR120.002216v1-mcp.TIR120.002216Technological Innovation and Resources Full Article
se ProAlanase is an Effective Alternative to Trypsin for Proteomics Applications and Disulfide Bond Mapping By www.mcponline.org Published On :: 2020-12-01 Diana SamodovaDec 1, 2020; 19:2139-2156Technological Innovation and Resources Full Article
se Plasma proteomic data can contain personally identifiable, sensitive information and incidental findings By www.mcponline.org Published On :: 2020-12-17 Philipp Emanuel GeyerDec 17, 2020; 0:RA120.002359v1-mcp.RA120.002359Research Full Article
se Secretory galectin-3 induced by glucocorticoid stress triggers stemness exhaustion of hepatic progenitor cells [Signal Transduction] By www.jbc.org Published On :: 2020-12-04T00:06:06-08:00 Adult progenitor cell populations typically exist in a quiescent state within a controlled niche environment. However, various stresses or forms of damage can disrupt this state, which often leads to dysfunction and aging. We built a glucocorticoid (GC)-induced liver damage model of mice, found that GC stress induced liver damage, leading to consequences for progenitor cells expansion. However, the mechanisms by which niche factors cause progenitor cells proliferation are largely unknown. We demonstrate that, within the liver progenitor cells niche, Galectin-3 (Gal-3) is responsible for driving a subset of progenitor cells to break quiescence. We show that GC stress causes aging of the niche, which induces the up-regulation of Gal-3. The increased Gal-3 population increasingly interacts with the progenitor cell marker CD133, which triggers focal adhesion kinase (FAK)/AMP-activated kinase (AMPK) signaling. This results in the loss of quiescence and leads to the eventual stemness exhaustion of progenitor cells. Conversely, blocking Gal-3 with the inhibitor TD139 prevents the loss of stemness and improves liver function. These experiments identify a stress-dependent change in progenitor cell niche that directly influence liver progenitor cell quiescence and function. Full Article
se Functions of Gle1 are governed by two distinct modes of self-association [Gene Regulation] By www.jbc.org Published On :: 2020-12-04T00:06:06-08:00 Gle1 is a conserved, essential regulator of DEAD-box RNA helicases, with critical roles defined in mRNA export, translation initiation, translation termination, and stress granule formation. Mechanisms that specify which, where, and when DDXs are targeted by Gle1 are critical to understand. In addition to roles for stress-induced phosphorylation and inositol hexakisphosphate binding in specifying Gle1 function, Gle1 oligomerizes via its N-terminal domain in a phosphorylation-dependent manner. However, a thorough analysis of the role for Gle1 self-association is lacking. Here, we find that Gle1 self-association is driven by two distinct regions: a coiled-coil domain and a novel 10-amino acid aggregation-prone region, both of which are necessary for proper Gle1 oligomerization. By exogenous expression in HeLa cells, we tested the function of a series of mutations that impact the oligomerization domains of the Gle1A and Gle1B isoforms. Gle1 oligomerization is necessary for many, but not all aspects of Gle1A and Gle1B function, and the requirements for each interaction domain differ. Whereas the coiled-coil domain and aggregation-prone region additively contribute to competent mRNA export and stress granule formation, both self-association domains are independently required for regulation of translation under cellular stress. In contrast, Gle1 self-association is dispensable for phosphorylation and nonstressed translation initiation. Collectively, we reveal self-association functions as an additional mode of Gle1 regulation to ensure proper mRNA export and translation. This work also provides further insight into the mechanisms underlying human gle1 disease mutants found in prenatally lethal forms of arthrogryposis. Full Article
se Agonist-activated glucagon receptors are deubiquitinated at early endosomes by two distinct deubiquitinases to facilitate Rab4a-dependent recycling [Signal Transduction] By www.jbc.org Published On :: 2020-12-04T00:06:05-08:00 The glucagon receptor (GCGR) activated by the peptide hormone glucagon is a seven-transmembrane G protein–coupled receptor (GPCR) that regulates blood glucose levels. Ubiquitination influences trafficking and signaling of many GPCRs, but its characterization for the GCGR is lacking. Using endocytic colocalization and ubiquitination assays, we have identified a correlation between the ubiquitination profile and recycling of the GCGR. Our experiments revealed that GCGRs are constitutively ubiquitinated at the cell surface. Glucagon stimulation not only promoted GCGR endocytic trafficking through Rab5a early endosomes and Rab4a recycling endosomes, but also induced rapid deubiquitination of GCGRs. Inhibiting GCGR internalization or disrupting endocytic trafficking prevented agonist-induced deubiquitination of the GCGR. Furthermore, a Rab4a dominant negative (DN) that blocks trafficking at recycling endosomes enabled GCGR deubiquitination, whereas a Rab5a DN that blocks trafficking at early endosomes eliminated agonist-induced GCGR deubiquitination. By down-regulating candidate deubiquitinases that are either linked with GPCR trafficking or localized on endosomes, we identified signal-transducing adaptor molecule–binding protein (STAMBP) and ubiquitin-specific protease 33 (USP33) as cognate deubiquitinases for the GCGR. Our data suggest that USP33 constitutively deubiquitinates the GCGR, whereas both STAMBP and USP33 deubiquitinate agonist-activated GCGRs at early endosomes. A mutant GCGR with all five intracellular lysines altered to arginines remains deubiquitinated and shows augmented trafficking to Rab4a recycling endosomes compared with the WT, thus affirming the role of deubiquitination in GCGR recycling. We conclude that the GCGRs are rapidly deubiquitinated after agonist-activation to facilitate Rab4a-dependent recycling and that USP33 and STAMBP activities are critical for the endocytic recycling of the GCGR. Full Article
se Integrin and autocrine IGF2 pathways control fasting insulin secretion in {beta}-cells [Signal Transduction] By www.jbc.org Published On :: 2020-12-04T00:06:05-08:00 Elevated levels of fasting insulin release and insufficient glucose-stimulated insulin secretion (GSIS) are hallmarks of diabetes. Studies have established cross-talk between integrin signaling and insulin activity, but more details of how integrin-dependent signaling impacts the pathophysiology of diabetes are needed. Here, we dissected integrin-dependent signaling pathways involved in the regulation of insulin secretion in β-cells and studied their link to the still debated autocrine regulation of insulin secretion by insulin/insulin-like growth factor (IGF) 2–AKT signaling. We observed for the first time a cooperation between different AKT isoforms and focal adhesion kinase (FAK)–dependent adhesion signaling, which either controlled GSIS or prevented insulin secretion under fasting conditions. Indeed, β-cells form integrin-containing adhesions, which provide anchorage to the pancreatic extracellular matrix and are the origin of intracellular signaling via FAK and paxillin. Under low-glucose conditions, β-cells adopt a starved adhesion phenotype consisting of actin stress fibers and large peripheral focal adhesion. In contrast, glucose stimulation induces cell spreading, actin remodeling, and point-like adhesions that contain phospho-FAK and phosphopaxillin, located in small protrusions. Rat primary β-cells and mouse insulinomas showed an adhesion remodeling during GSIS resulting from autocrine insulin/IGF2 and AKT1 signaling. However, under starving conditions, the maintenance of stress fibers and the large adhesion phenotype required autocrine IGF2-IGF1 receptor signaling mediated by AKT2 and elevated FAK-kinase activity and ROCK-RhoA levels but low levels of paxillin phosphorylation. This starved adhesion phenotype prevented excessive insulin granule release to maintain low insulin secretion during fasting. Thus, deregulation of the IGF2 and adhesion-mediated signaling may explain dysfunctions observed in diabetes. Full Article
se Iron-mediated degradation of ribosomes under oxidative stress is attenuated by manganese [Cell Biology] By www.jbc.org Published On :: 2020-12-11T00:06:20-08:00 Protein biosynthesis is fundamental to cellular life and requires the efficient functioning of the translational machinery. At the center of this machinery is the ribosome, a ribonucleoprotein complex that depends heavily on Mg2+ for structure. Recent work has indicated that other metal cations can substitute for Mg2+, raising questions about the role different metals may play in the maintenance of the ribosome under oxidative stress conditions. Here, we assess ribosomal integrity following oxidative stress both in vitro and in cells to elucidate details of the interactions between Fe2+ and the ribosome and identify Mn2+ as a factor capable of attenuating oxidant-induced Fe2+-mediated degradation of rRNA. We report that Fe2+ promotes degradation of all rRNA species of the yeast ribosome and that it is bound directly to RNA molecules. Furthermore, we demonstrate that Mn2+ competes with Fe2+ for rRNA-binding sites and that protection of ribosomes from Fe2+-mediated rRNA hydrolysis correlates with the restoration of cell viability. Our data, therefore, suggest a relationship between these two transition metals in controlling ribosome stability under oxidative stress. Full Article
se Dysregulation of hsa-miR-34a and hsa-miR-449a leads to overexpression of PACS-1 and loss of DNA damage response (DDR) in cervical cancer [Cell Biology] By www.jbc.org Published On :: 2020-12-11T00:06:20-08:00 We have observed overexpression of PACS-1, a cytosolic sorting protein in primary cervical tumors. Absence of exonic mutations and overexpression at the RNA level suggested a transcriptional and/or posttranscriptional regulation. University of California Santa Cruz genome browser analysis of PACS-1 micro RNAs (miR), revealed two 8-base target sequences at the 3' terminus for hsa-miR-34a and hsa-miR-449a. Quantitative RT-PCR and Northern blotting studies showed reduced or loss of expression of the two microRNAs in cervical cancer cell lines and primary tumors, indicating dysregulation of these two microRNAs in cervical cancer. Loss of PACS-1 with siRNA or exogenous expression of hsa-miR-34a or hsa-miR-449a in HeLa and SiHa cervical cancer cell lines resulted in DNA damage response, S-phase cell cycle arrest, and reduction in cell growth. Furthermore, the siRNA studies showed that loss of PACS-1 expression was accompanied by increased nuclear γH2AX expression, Lys382-p53 acetylation, and genomic instability. PACS-1 re-expression through LNA-hsa-anti-miR-34a or -449a or through PACS-1 cDNA transfection led to the reversal of DNA damage response and restoration of cell growth. Release of cells post 24-h serum starvation showed PACS-1 nuclear localization at G1-S phase of the cell cycle. Our results therefore indicate that the loss of hsa-miR-34a and hsa-miR-449a expression in cervical cancer leads to overexpression of PACS-1 and suppression of DNA damage response, resulting in the development of chemo-resistant tumors. Full Article
se Interrogation of kinase genetic interactions provides a global view of PAK1-mediated signal transduction pathways [Gene Regulation] By www.jbc.org Published On :: 2020-12-11T00:06:20-08:00 Kinases are critical components of intracellular signaling pathways and have been extensively investigated with regard to their roles in cancer. p21-activated kinase-1 (PAK1) is a serine/threonine kinase that has been previously implicated in numerous biological processes, such as cell migration, cell cycle progression, cell motility, invasion, and angiogenesis, in glioma and other cancers. However, the signaling network linked to PAK1 is not fully defined. We previously reported a large-scale yeast genetic interaction screen using toxicity as a readout to identify candidate PAK1 genetic interactions. En masse transformation of the PAK1 gene into 4,653 homozygous diploid Saccharomyces cerevisiae yeast deletion mutants identified ∼400 candidates that suppressed yeast toxicity. Here we selected 19 candidate PAK1 genetic interactions that had human orthologs and were expressed in glioma for further examination in mammalian cells, brain slice cultures, and orthotopic glioma models. RNAi and pharmacological inhibition of potential PAK1 interactors confirmed that DPP4, KIF11, mTOR, PKM2, SGPP1, TTK, and YWHAE regulate PAK1-induced cell migration and revealed the importance of genes related to the mitotic spindle, proteolysis, autophagy, and metabolism in PAK1-mediated glioma cell migration, drug resistance, and proliferation. AKT1 was further identified as a downstream mediator of the PAK1-TTK genetic interaction. Taken together, these data provide a global view of PAK1-mediated signal transduction pathways and point to potential new drug targets for glioma therapy. Full Article
se Clearance of intracellular tau protein from neuronal cells via VAMP8-induced secretion [Cell Biology] By www.jbc.org Published On :: 2020-12-18T00:06:18-08:00 In Alzheimer's disease (AD), tau, a microtubule-associated protein (MAP), becomes hyperphosphorylated, aggregates, and accumulates in the somato-dendritic compartment of neurons. In parallel to its intracellular accumulation in AD, tau is also released in the extracellular space, as revealed by its increased presence in cerebrospinal fluid (CSF). Consistent with this, recent studies, including ours, have reported that neurons secrete tau, and several therapeutic strategies aim to prevent the intracellular tau accumulation. Previously, we reported that late endosomes were implicated in tau secretion. Here, we explore the possibility of preventing intracellular tau accumulation by increasing tau secretion. Using neuronal models, we investigated whether overexpression of the vesicle-associated membrane protein 8 (VAMP8), an R-SNARE found on late endosomes, could increase tau secretion. The overexpression of VAMP8 significantly increased tau secretion, decreasing its intracellular levels in the neuroblastoma (N2a) cell line. Increased tau secretion by VAMP8 was also observed in murine hippocampal slices. The intracellular reduction of tau by VAMP8 overexpression correlated to a decrease of acetylated tubulin induced by tau overexpression in N2a cells. VAMP8 staining was preferentially found on late endosomes in N2a cells. Using total internal reflection fluorescence (TIRF) microscopy, the fusion of VAMP8-positive vesicles with the plasma membrane was correlated to the depletion of tau in the cytoplasm. Finally, overexpression of VAMP8 reduced the intracellular accumulation of tau mutants linked to frontotemporal dementia with parkinsonism and α-synuclein by increasing their secretion. Collectively, the present data indicate that VAMP8 could be used to increase tau and α-synuclein clearance to prevent their intracellular accumulation. Full Article
se AggreCount: an unbiased image analysis tool for identifying and quantifying cellular aggregates in a spatially defined manner [Methods and Resources] By www.jbc.org Published On :: 2020-12-18T00:06:18-08:00 Protein quality control is maintained by a number of integrated cellular pathways that monitor the folding and functionality of the cellular proteome. Defects in these pathways lead to the accumulation of misfolded or faulty proteins that may become insoluble and aggregate over time. Protein aggregates significantly contribute to the development of a number of human diseases such as amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease. In vitro, imaging-based, cellular studies have defined key biomolecular components that recognize and clear aggregates; however, no unifying method is available to quantify cellular aggregates, limiting our ability to reproducibly and accurately quantify these structures. Here we describe an ImageJ macro called AggreCount to identify and measure protein aggregates in cells. AggreCount is designed to be intuitive, easy to use, and customizable for different types of aggregates observed in cells. Minimal experience in coding is required to utilize the script. Based on a user-defined image, AggreCount will report a number of metrics: (i) total number of cellular aggregates, (ii) percentage of cells with aggregates, (iii) aggregates per cell, (iv) area of aggregates, and (v) localization of aggregates (cytosol, perinuclear, or nuclear). A data table of aggregate information on a per cell basis, as well as a summary table, is provided for further data analysis. We demonstrate the versatility of AggreCount by analyzing a number of different cellular aggregates including aggresomes, stress granules, and inclusion bodies caused by huntingtin polyglutamine expansion. Full Article
se NETosis occurs independently of neutrophil serine proteases [Enzymology] By www.jbc.org Published On :: 2020-12-18T00:06:18-08:00 Neutrophils are primary host innate immune cells defending against pathogens. One proposed mechanism by which neutrophils prevent the spread of pathogens is NETosis, the extrusion of cellular DNA resulting in neutrophil extracellular traps (NETs). The protease neutrophil elastase (NE) has been implicated in the formation of NETs through proteolysis of nuclear proteins leading to chromatin decondensation. In addition to NE, neutrophils contain three other serine proteases that could compensate if the activity of NE was neutralized. However, whether they do play such a role is unknown. Thus, we deployed recently described specific inhibitors against all four of the neutrophil serine proteases (NSPs). Using specific antibodies to the NSPs along with our labeled inhibitors, we show that catalytic activity of these enzymes is not required for the formation of NETs. Moreover, the NSPs that decorate NETs are in an inactive conformation and thus cannot participate in further catalytic events. These results indicate that NSPs play no role in either NETosis or arming NETs with proteolytic activity. Full Article
se GUCY2D mutations in retinal guanylyl cyclase 1 provide biochemical reasons for dominant cone-rod dystrophy but not for stationary night blindness [Cell Biology] By www.jbc.org Published On :: 2020-12-25T00:06:31-08:00 Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB. Full Article
se Distant coupling between RNA editing and alternative splicing of the osmosensitive cation channel Tmem63b [Cell Biology] By www.jbc.org Published On :: 2020-12-25T00:06:30-08:00 Post-transcriptional modifications of pre-mRNAs expand the diversity of proteomes in higher eukaryotes. In the brain, these modifications diversify the functional output of many critical neuronal signal molecules. In this study, we identified a brain-specific A-to-I RNA editing that changed glutamine to arginine (Q/R) at exon 20 and an alternative splicing of exon 4 in Tmem63b, which encodes a ubiquitously expressed osmosensitive cation channel. The channel isoforms lacking exon 4 occurred in ∼80% of Tmem63b mRNAs in the brain but were not detected in other tissues, suggesting a brain-specific splicing. We found that the Q/R editing was catalyzed by Adar2 (Adarb1) and required an editing site complementary sequence located in the proximal 5' end of intron 20. Moreover, the Q/R editing was almost exclusively identified in the splicing isoform lacking exon 4, indicating a coupling between the editing and the splicing. Elimination of the Q/R editing in brain-specific Adar2 knockout mice did not affect the splicing efficiency of exon 4. Furthermore, transfection with the splicing isoform containing exon 4 suppressed the Q/R editing in primary cultured cerebellar granule neurons. Thus, our study revealed a coupling between an RNA editing and a distant alternative splicing in the Tmem63b pre-mRNA, in which the splicing plays a dominant role. Finally, physiological analysis showed that the splicing and the editing coordinately regulate Ca2+ permeability and osmosensitivity of channel proteins, which may contribute to their functions in the brain. Full Article
se PDE5 inhibition rescues mitochondrial dysfunction and angiogenic responses induced by Akt3 inhibition by promotion of PRC expression [Bioenergetics] By www.jbc.org Published On :: 2020-12-25T00:06:30-08:00 Akt3 regulates mitochondrial content in endothelial cells through the inhibition of PGC-1α nuclear localization and is also required for angiogenesis. However, whether there is a direct link between mitochondrial function and angiogenesis is unknown. Here we show that Akt3 depletion in primary endothelial cells results in decreased uncoupled oxygen consumption, increased fission, decreased membrane potential, and increased expression of the mitochondria-specific protein chaperones, HSP60 and HSP10, suggesting that Akt3 is required for mitochondrial homeostasis. Direct inhibition of mitochondrial homeostasis by the model oxidant paraquat results in decreased angiogenesis, showing a direct link between angiogenesis and mitochondrial function. Next, in exploring functional links to PGC-1α, the master regulator of mitochondrial biogenesis, we searched for compounds that induce this process. We found that, sildenafil, a phosphodiesterase 5 inhibitor, induced mitochondrial biogenesis as measured by increased uncoupled oxygen consumption, mitochondrial DNA content, and voltage-dependent anion channel protein expression. Sildenafil rescued the effects on mitochondria by Akt3 depletion or pharmacological inhibition and promoted angiogenesis, further supporting that mitochondrial homeostasis is required for angiogenesis. Sildenafil also induces the expression of PGC-1 family member PRC and can compensate for PGC-1α activity during mitochondrial stress by an Akt3-independent mechanism. The induction of PRC by sildenafil depends upon cAMP and the transcription factor CREB. Thus, PRC can functionally substitute during Akt3 depletion for absent PGC-1α activity to restore mitochondrial homeostasis and promote angiogenesis. These findings show that mitochondrial homeostasis as controlled by the PGC family of transcriptional activators is required for angiogenic responses. Full Article
se HIV-1 Gag release from yeast reveals ESCRT interaction with the Gag N-terminal protein region [Molecular Bases of Disease] By www.jbc.org Published On :: 2020-12-25T00:06:30-08:00 The HIV-1 protein Gag assembles at the plasma membrane and drives virion budding, assisted by the cellular endosomal complex required for transport (ESCRT) proteins. Two ESCRT proteins, TSG101 and ALIX, bind to the Gag C-terminal p6 peptide. TSG101 binding is important for efficient HIV-1 release, but how ESCRTs contribute to the budding process and how their activity is coordinated with Gag assembly is poorly understood. Yeast, allowing genetic manipulation that is not easily available in human cells, has been used to characterize the cellular ESCRT function. Previous work reported Gag budding from yeast spheroplasts, but Gag release was ESCRT-independent. We developed a yeast model for ESCRT-dependent Gag release. We combined yeast genetics and Gag mutational analysis with Gag-ESCRT binding studies and the characterization of Gag-plasma membrane binding and Gag release. With our system, we identified a previously unknown interaction between ESCRT proteins and the Gag N-terminal protein region. Mutations in the Gag-plasma membrane–binding matrix domain that reduced Gag-ESCRT binding increased Gag-plasma membrane binding and Gag release. ESCRT knockout mutants showed that the release enhancement was an ESCRT-dependent effect. Similarly, matrix mutation enhanced Gag release from human HEK293 cells. Release enhancement partly depended on ALIX binding to p6, although binding site mutation did not impair WT Gag release. Accordingly, the relative affinity for matrix compared with p6 in GST-pulldown experiments was higher for ALIX than for TSG101. We suggest that a transient matrix-ESCRT interaction is replaced when Gag binds to the plasma membrane. This step may activate ESCRT proteins and thereby coordinate ESCRT function with virion assembly. Full Article
se Exploitation of dihydroorotate dehydrogenase (DHODH) and p53 activation as therapeutic targets: A case study in polypharmacology [Computational Biology] By www.jbc.org Published On :: 2020-12-25T00:06:30-08:00 The tenovins are a frequently studied class of compounds capable of inhibiting sirtuin activity, which is thought to result in increased acetylation and protection of the tumor suppressor p53 from degradation. However, as we and other laboratories have shown previously, certain tenovins are also capable of inhibiting autophagic flux, demonstrating the ability of these compounds to engage with more than one target. In this study, we present two additional mechanisms by which tenovins are able to activate p53 and kill tumor cells in culture. These mechanisms are the inhibition of a key enzyme of the de novo pyrimidine synthesis pathway, dihydroorotate dehydrogenase (DHODH), and the blockage of uridine transport into cells. These findings hold a 3-fold significance: first, we demonstrate that tenovins, and perhaps other compounds that activate p53, may activate p53 by more than one mechanism; second, that work previously conducted with certain tenovins as SirT1 inhibitors should additionally be viewed through the lens of DHODH inhibition as this is a major contributor to the mechanism of action of the most widely used tenovins; and finally, that small changes in the structure of a small molecule can lead to a dramatic change in the target profile of the molecule even when the phenotypic readout remains static. Full Article
se A kinetic dissection of the fast and superprocessive kinesin-3 KIF1A reveals a predominant one-head-bound state during its chemomechanical cycle [Molecular Biophysics] By www.jbc.org Published On :: 2020-12-25T00:06:30-08:00 The kinesin-3 family contains the fastest and most processive motors of the three neuronal transport kinesin families, yet the sequence of states and rates of kinetic transitions that comprise the chemomechanical cycle and give rise to their unique properties are poorly understood. We used stopped-flow fluorescence spectroscopy and single-molecule motility assays to delineate the chemomechanical cycle of the kinesin-3, KIF1A. Our bacterially expressed KIF1A construct, dimerized via a kinesin-1 coiled-coil, exhibits fast velocity and superprocessivity behavior similar to WT KIF1A. We established that the KIF1A forward step is triggered by hydrolysis of ATP and not by ATP binding, meaning that KIF1A follows the same chemomechanical cycle as established for kinesin-1 and -2. The ATP-triggered half-site release rate of KIF1A was similar to the stepping rate, indicating that during stepping, rear-head detachment is an order of magnitude faster than in kinesin-1 and kinesin-2. Thus, KIF1A spends the majority of its hydrolysis cycle in a one-head-bound state. Both the ADP off-rate and the ATP on-rate at physiological ATP concentration were fast, eliminating these steps as possible rate-limiting transitions. Based on the measured run length and the relatively slow off-rate in ADP, we conclude that attachment of the tethered head is the rate-limiting transition in the KIF1A stepping cycle. Thus, KIF1A's activity can be explained by a fast rear-head detachment rate, a rate-limiting step of tethered-head attachment that follows ATP hydrolysis, and a relatively strong electrostatic interaction with the microtubule in the weakly bound post-hydrolysis state. Full Article
se Hsa-miRNA-23a-3p promotes atherogenesis in a novel mouse model of atherosclerosis By www.jlr.org Published On :: 2020-12-01 Jiayan GuoDec 1, 2020; 61:1764-1775Research Articles Full Article
se Stimulation of ABCB4/MDR3 ATPase activity requires an intact phosphatidylcholine lipid By www.jlr.org Published On :: 2020-12-01 Martin PrescherDec 1, 2020; 61:1605-1616Research Articles Full Article
se A novel phosphoglycerol serine-glycine lipodipeptide of Porphyromonas gingivalis is a TLR2 ligand By www.jlr.org Published On :: 2020-12-01 Frank C. NicholsDec 1, 2020; 61:1645-1657Research Articles Full Article
se PLRP2 selectively localizes synaptic membrane proteins via acyl-chain remodeling of phospholipids By www.jlr.org Published On :: 2020-12-01 Hideaki KugeDec 1, 2020; 61:1747-1763Research Articles Full Article
se Progression of chronic kidney disease in familial LCAT deficiency: a follow-up of the Italian cohort By www.jlr.org Published On :: 2020-12-01 Chiara PavanelloDec 1, 2020; 61:1784-1788Patient-Oriented and Epidemiological Research Full Article
se Depletion of essential isoprenoids and ER stress induction following acute liver-specific deletion of HMG-CoA reductase By www.jlr.org Published On :: 2020-12-01 Marco De GiorgiDec 1, 2020; 61:1675-1686Research Articles Full Article
se A review of phosphatidate phosphatase assays By www.jlr.org Published On :: 2020-12-01 Prabuddha DeyDec 1, 2020; 61:1556-1564Reviews Full Article
se Human glucocerebrosidase mediates formation of xylosyl-cholesterol by {beta}-xylosidase and transxylosidase reactions. By www.jlr.org Published On :: 2020-12-23 Daphne E.C. BoerDec 23, 2020; 0:jlr.RA120001043v1-jlr.RA120001043Research Articles Full Article
se Spatial profiling of gangliosides in mouse brain by mass spectrometry imaging By www.jlr.org Published On :: 2020-12-01 Douglas A. AndresDec 1, 2020; 61:1537-1537Images in Lipid Research Full Article
se LDL apheresis as an alternate method for plasma LPS purification in healthy volunteers and dyslipidemic and septic patients By www.jlr.org Published On :: 2020-12-01 Auguste DargentDec 1, 2020; 61:1776-1783Research Articles Full Article
se Lipid signature of advanced human carotid atherosclerosis assessed by mass spectrometry imaging By www.jlr.org Published On :: 2020-12-23 Astrid M. MoermanDec 23, 2020; 0:jlr.RA120000974v1-jlr.RA120000974Research Articles Full Article
se Deletion of lysophosphatidylcholine acyltransferase3 in myeloid cells worsens hepatic steatosis after a high fat diet By www.jlr.org Published On :: 2020-12-11 Thibaut BourgeoisDec 11, 2020; 0:jlr.RA120000737v1-jlr.RA120000737Research Articles Full Article
se Human CETP lacks lipopolysaccharide transfer activity, but worsens inflammation and sepsis outcomes in mice By www.jlr.org Published On :: 2020-12-09 Aloïs DusuelDec 9, 2020; 0:jlr.RA120000704v1-jlr.RA120000704Research Articles Full Article
se SCD1 promotes lipid mobilization in subcutaneous white adipose tissue By www.jlr.org Published On :: 2020-12-01 Ying ZouDec 1, 2020; 61:1589-1604Research Articles Full Article
se Structure dynamics of ApoA-I amyloidogenic variants in small HDL increase their ability to mediate cholesterol efflux By www.jlr.org Published On :: 2020-11-17 Oktawia NilssonNov 17, 2020; 0:jlr.RA120000920v1-jlr.RA120000920Research Articles Full Article
se Distinct patterns of apolipoprotein C-I, C-II and C-III isoforms are associated with markers of Alzheimers disease By www.jlr.org Published On :: 2020-12-11 Yueming HuDec 11, 2020; 0:jlr.RA120000919v1-jlr.RA120000919Research Articles Full Article
se Generation and validation of a conditional knockout mouse model for the study of the Smith-Lemli-Opitz Syndrome By www.jlr.org Published On :: 2020-11-17 Babunageswararao KanuriNov 17, 2020; 0:jlr.RA120001101v1-jlr.RA120001101Research Articles Full Article
se Multi-modal Functional Imaging of Brown Adipose Tissue By www.jlr.org Published On :: 2020-11-18 Amanda D.V. MacCannellNov 18, 2020; 0:jlr.ILR120001204v1-jlr.ILR120001204Images in Lipid Research Full Article
se Problem Notes for SAS®9 - 66438: You see the message "The informat $ could not be loaded, probably due to insufficient memory" after attempting to insert data into a MySQL database By Published On :: Wed, 2 Sep 2020 10:39:14 EST For data that is being loaded from a SAS Stored Process Server, an insertion process might fail to a MySQL database with a warning, as well as an error message that says "During insert: Incorrect datetime value " Full Article BASE+Base+SAS
se Problem Notes for SAS®9 - 66539: A new calculated variable that you create in the Edit Value dialog box is not available for selection in SAS Customer Intelligence Studio By Published On :: Tue, 1 Sep 2020 13:44:23 EST In SAS Customer Intelligence Studio, you can choose to create a new calculated variable in the Edit Value dialog box when you populate a treatment custom detail. Following creation of the new calculated Full Article CAMPAIGNSDO+SAS+Customer+Intelligence+St
se Problem Notes for SAS®9 - 66527: Updating counts in a Link node in SAS Customer Intelligence Studio produces the error "Link: MAIQService:executeFastPath:" By Published On :: Tue, 1 Sep 2020 10:53:01 EST In SAS Customer Intelligence Studio, the following error is displayed when you update a new Link node in a diagram: imgalt="Link: MAIQService:executeFastPath:" src="{fusion_665 Full Article CAMPAIGNSDO+SAS+Customer+Intelligence+St