of Proteomic identification of Coxiella burnetii effector proteins targeted to the host cell mitochondria during infection By www.mcponline.org Published On :: 2020-11-11 Laura F FieldenNov 11, 2020; 0:RA120.002370v1-mcp.RA120.002370Research Full Article
of The peptide vaccine of the future By www.mcponline.org Published On :: 2020-12-07 Annika NeldeDec 7, 2020; 0:R120.002309v1-mcp.R120.002309Review Full Article
of 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
of 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
of Mutation-independent Proteomic Signatures of Pathological Progression in Murine Models of Duchenne Muscular Dystrophy By www.mcponline.org Published On :: 2020-12-01 Tirsa L. E. van WesteringDec 1, 2020; 19:2047-2067Research Full Article
of Protein modification characteristics of the malaria parasite Plasmodium falciparum and the infected erythrocytes By www.mcponline.org Published On :: 2020-11-04 Jianhua WangNov 4, 2020; 0:RA120.002375v1-mcp.RA120.002375Research Full Article
of Pluripotency of embryonic stem cells lacking clathrin-mediated endocytosis cannot be rescued by restoring cellular stiffness [Molecular Biophysics] By www.jbc.org Published On :: 2020-12-04T00:06:06-08:00 Mouse embryonic stem cells (mESCs) display unique mechanical properties, including low cellular stiffness in contrast to differentiated cells, which are stiffer. We have previously shown that mESCs lacking the clathrin heavy chain (Cltc), an essential component for clathrin-mediated endocytosis (CME), display a loss of pluripotency and an enhanced expression of differentiation markers. However, it is not known whether physical properties such as cellular stiffness also change upon loss of Cltc, similar to what is seen in differentiated cells, and if so, how these altered properties specifically impact pluripotency. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking Cltc display higher Young's modulus, indicative of greater cellular stiffness, compared with WT mESCs. The increase in stiffness was accompanied by the presence of actin stress fibers and accumulation of the inactive, phosphorylated, actin-binding protein cofilin. Treatment of Cltc knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young's modulus to values similar to those obtained with WT mESCs. However, a rescue in the expression profile of pluripotency factors was not obtained. Additionally, whereas WT mouse embryonic fibroblasts could be reprogrammed to a state of pluripotency, this was inhibited in the absence of Cltc. This indicates that the presence of active CME is essential for the pluripotency of embryonic stem cells. Additionally, whereas physical properties may serve as a simple readout of the cellular state, they may not always faithfully recapitulate the underlying molecular fate. Full Article
of 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
of VBP1 modulates Wnt/{beta}-catenin signaling by mediating the stability of the transcription factors TCF/LEFs [Signal Transduction] By www.jbc.org Published On :: 2020-12-04T00:06:06-08:00 The Wnt/β-catenin pathway is one of the major pathways that regulates embryonic development, adult homeostasis, and stem cell self-renewal. In this pathway, transcription factors T-cell factor and lymphoid enhancer factor (TCF/LEF) serve as a key switch to repress or activate Wnt target gene transcription by recruiting repressor molecules or interacting with the β-catenin effector, respectively. It has become evident that the protein stability of the TCF/LEF family members may play a critical role in controlling the activity of the Wnt/β-catenin signaling pathway. However, factors that regulate the stability of TCF/LEFs remain largely unknown. Here, we report that pVHL binding protein 1 (VBP1) regulates the Wnt/β-catenin signaling pathway by controlling the stability of TCF/LEFs. Surprisingly, we found that either overexpression or knockdown of VBP1 decreased Wnt/β-catenin signaling activity in both cultured cells and zebrafish embryos. Mechanistically, VBP1 directly binds to all four TCF/LEF family members and von Hippel-Lindau tumor-suppressor protein (pVHL). Either overexpression or knockdown of VBP1 increases the association between TCF/LEFs and pVHL and then decreases the protein levels of TCF/LEFs via proteasomal degradation. Together, our results provide mechanistic insights into the roles of VBP1 in controlling TCF/LEFs protein stability and regulating Wnt/β-catenin signaling pathway activity. Full Article
of 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
of The amphipathic helices of Arfrp1 and Arl14 are sufficient to determine subcellular localizations [Cell Biology] By www.jbc.org Published On :: 2020-12-04T00:06:05-08:00 The subcellular localization of Arf family proteins is generally thought to be determined by their corresponding guanine nucleotide exchange factors. By promoting GTP binding, guanine nucleotide exchange factors induce conformational changes of Arf proteins exposing their N-terminal amphipathic helices, which then insert into the membranes to stabilize the membrane association process. Here, we found that the N-terminal amphipathic motifs of the Golgi-localized Arf family protein, Arfrp1, and the endosome- and plasma membrane–localized Arf family protein, Arl14, play critical roles in spatial determination. Exchanging the amphipathic helix motifs between these two Arf proteins causes the switch of their localizations. Moreover, the amphipathic helices of Arfrp1 and Arl14 are sufficient for cytosolic proteins to be localized into a specific cellular compartment. The spatial determination mediated by the Arfrp1 helix requires its binding partner Sys1. In addition, the residues that are required for the acetylation of the Arfrp1 helix and the myristoylation of the Arl14 helix are important for the specific subcellular localization. Interestingly, Arfrp1 and Arl14 are recruited to their specific cellular compartments independent of GTP binding. Our results demonstrate that the amphipathic motifs of Arfrp1 and Arl14 are sufficient for determining specific subcellular localizations in a GTP-independent manner, suggesting that the membrane association and activation of some Arf proteins are uncoupled. Full Article
of Site-specific contacts enable distinct modes of TRPV1 regulation by the potassium channel Kv{beta}1 subunit [Molecular Biophysics] By www.jbc.org Published On :: 2020-12-11T00:06:21-08:00 Transient receptor potential vanilloid 1 (TRPV1) channel is a multimodal receptor that is responsible for nociceptive, thermal, and mechanical sensations. However, which biomolecular partners specifically interact with TRPV1 remains to be elucidated. Here, we used cDNA library screening of genes from mouse dorsal root ganglia combined with patch-clamp electrophysiology to identify the voltage-gated potassium channel auxiliary subunit Kvβ1 physically interacting with TRPV1 channel and regulating its function. The interaction was validated in situ using endogenous dorsal root ganglia neurons, as well as a recombinant expression model in HEK 293T cells. The presence of Kvβ1 enhanced the expression stability of TRPV1 channels on the plasma membrane and the nociceptive current density. Surprisingly, Kvβ1 interaction also shifted the temperature threshold for TRPV1 thermal activation. Using site-specific mapping, we further revealed that Kvβ1 interacted with the membrane-distal domain and membrane-proximal domain of TRPV1 to regulate its membrane expression and temperature-activation threshold, respectively. Our data therefore suggest that Kvβ1 is a key element in the TRPV1 signaling complex and exerts dual regulatory effects in a site-specific manner. Full Article
of 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
of 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
of 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
of 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
of AMPK{beta}1 and AMPK{beta}2 define an isoform-specific gene signature in human pluripotent stem cells, differentially mediating cardiac lineage specification [Cell Biology] By www.jbc.org Published On :: 2020-12-18T00:06:18-08:00 AMP-activated protein kinase (AMPK) is a key regulator of energy metabolism that phosphorylates a wide range of proteins to maintain cellular homeostasis. AMPK consists of three subunits: α, β, and γ. AMPKα and β are encoded by two genes, the γ subunit by three genes, all of which are expressed in a tissue-specific manner. It is not fully understood, whether individual isoforms have different functions. Using RNA-Seq technology, we provide evidence that the loss of AMPKβ1 and AMPKβ2 lead to different gene expression profiles in human induced pluripotent stem cells (hiPSCs), indicating isoform-specific function. The knockout of AMPKβ2 was associated with a higher number of differentially regulated genes than the deletion of AMPKβ1, suggesting that AMPKβ2 has a more comprehensive impact on the transcriptome. Bioinformatics analysis identified cell differentiation as one biological function being specifically associated with AMPKβ2. Correspondingly, the two isoforms differentially affected lineage decision toward a cardiac cell fate. Although the lack of PRKAB1 impacted differentiation into cardiomyocytes only at late stages of cardiac maturation, the availability of PRKAB2 was indispensable for mesoderm specification as shown by gene expression analysis and histochemical staining for cardiac lineage markers such as cTnT, GATA4, and NKX2.5. Ultimately, the lack of AMPKβ1 impairs, whereas deficiency of AMPKβ2 abrogates differentiation into cardiomyocytes. Finally, we demonstrate that AMPK affects cellular physiology by engaging in the regulation of hiPSC transcription in an isoform-specific manner, providing the basis for further investigations elucidating the role of dedicated AMPK subunits in the modulation of gene expression. Full Article
of 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
of PTPN2 regulates the activation of KRAS and plays a critical role in proliferation and survival of KRAS-driven cancer cells [Signal Transduction] By www.jbc.org Published On :: 2020-12-25T00:06:31-08:00 RAS genes are the most commonly mutated in human cancers and play critical roles in tumor initiation, progression, and drug resistance. Identification of targets that block RAS signaling is pivotal to develop therapies for RAS-related cancer. As RAS translocation to the plasma membrane (PM) is essential for its effective signal transduction, we devised a high-content screening assay to search for genes regulating KRAS membrane association. We found that the tyrosine phosphatase PTPN2 regulates the plasma membrane localization of KRAS. Knockdown of PTPN2 reduced the proliferation and promoted apoptosis in KRAS-dependent cancer cells, but not in KRAS-independent cells. Mechanistically, PTPN2 negatively regulates tyrosine phosphorylation of KRAS, which, in turn, affects the activation KRAS and its downstream signaling. Consistently, analysis of the TCGA database demonstrates that high expression of PTPN2 is significantly associated with poor prognosis of patients with KRAS-mutant pancreatic adenocarcinoma. These results indicate that PTPN2 is a key regulator of KRAS and may serve as a new target for therapy of KRAS-driven cancer. Full Article
of Therapeutic targeting of pancreatic cancer stem cells by dexamethasone modulation of the MKP-1-JNK axis [Cell Biology] By www.jbc.org Published On :: 2020-12-25T00:06:31-08:00 Postoperative recurrence from microscopic residual disease must be prevented to cure intractable cancers, including pancreatic cancer. Key to this goal is the elimination of cancer stem cells (CSCs) endowed with tumor-initiating capacity and drug resistance. However, current therapeutic strategies capable of accomplishing this are insufficient. Using in vitro models of CSCs and in vivo models of tumor initiation in which CSCs give rise to xenograft tumors, we show that dexamethasone induces expression of MKP-1, a MAPK phosphatase, via glucocorticoid receptor activation, thereby inactivating JNK, which is required for self-renewal and tumor initiation by pancreatic CSCs as well as for their expression of survivin, an anti-apoptotic protein implicated in multidrug resistance. We also demonstrate that systemic administration of clinically relevant doses of dexamethasone together with gemcitabine prevents tumor formation by CSCs in a pancreatic cancer xenograft model. Our study thus provides preclinical evidence for the efficacy of dexamethasone as an adjuvant therapy to prevent postoperative recurrence in patients with pancreatic cancer. Full Article
of 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
of 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
of 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
of 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
of 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
of Palmitoylation of acetylated tubulin and association with ceramide-rich platforms is critical for ciliogenesis By www.jlr.org Published On :: 2020-12-30 Priyanka TripathiDec 30, 2020; 0:jlr.RA120001190v1-jlr.RA120001190Research Articles Full Article
of High resolution structure of human apolipoprotein (a) kringle IV type 2: beyond the lysine binding site By www.jlr.org Published On :: 2020-12-01 Alice SantonastasoDec 1, 2020; 61:1687-1696Research Articles Full Article
of Nuclear translocation ability of Lipin differentially affects gene expression and survival in fed and fasting Drosophila By www.jlr.org Published On :: 2020-12-01 Stephanie E. HoodDec 1, 2020; 61:1720-1732Research Articles Full Article
of 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
of 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
of 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
of 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
of 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
of Bioavailability and spatial distribution of fatty acids in the rat retina after dietary omega-3 supplementation By www.jlr.org Published On :: 2020-12-01 Elisa VidalDec 1, 2020; 61:1733-1746Research Articles Full Article
of 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
of A review of phosphatidate phosphatase assays By www.jlr.org Published On :: 2020-12-01 Prabuddha DeyDec 1, 2020; 61:1556-1564Reviews Full Article
of 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
of 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
of Myeloid deletion and therapeutic activation of AMPK do not alter atherosclerosis in male or female mice By www.jlr.org Published On :: 2020-12-01 Nicholas D. LeBlondDec 1, 2020; 61:1697-1706Research Articles Full Article
of 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
of The anti-tubercular activity of simvastatin is mediated by cholesterol-driven autophagy via the AMPK-mTORC1-TFEB axis By www.jlr.org Published On :: 2020-12-01 Natalie BruinersDec 1, 2020; 61:1617-1628Research Articles Full Article
of Identification of unusual phospholipids from bovine heart mitochondria by HPLC-MS/MS By www.jlr.org Published On :: 2020-12-01 Junhwan KimDec 1, 2020; 61:1707-1719Research Articles Full Article
of 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
of Mutation in the distal NPxY motif of LRP1 alleviates dietary cholesterol-induced dyslipidemia and tissue inflammation By www.jlr.org Published On :: 2020-12-09 Anja JaeschkeDec 9, 2020; 0:jlr.RA120001141v1-jlr.RA120001141Research Articles Full Article
of Membrane-bound sn-1,2-diacylglycerols explain the dissociation of hepatic insulin resistance from hepatic steatosis in MTTP knockout mice By www.jlr.org Published On :: 2020-12-01 Abudukadier AbuliziDec 1, 2020; 61:1565-1576Research Articles Full Article
of 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
of rHDL modelling and the anchoring mechanism of LCAT activation By www.jlr.org Published On :: 2020-12-02 Tommaso LaurenziDec 2, 2020; 0:jlr.RA120000843v1-jlr.RA120000843Research Articles Full Article
of Insights on the kinetics and dynamics of the furin-cleaved form of PCSK9 By www.jlr.org Published On :: 2020-11-17 Carlota OleagaNov 17, 2020; 0:jlr.RA120000964v1-jlr.RA120000964Research Articles Full Article
of 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
of 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