Journal of Biological Chemistry (J Biol Chem )

Publisher: American Society for Biochemistry and Molecular Biology, American Society for Biochemistry and Molecular Biology


Complete content of the Journal of Biological Chemistry as of April 1995.

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  • 5-year impact
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  • Website
    Journal of Biological Chemistry website
  • Other titles
    Journal of biological chemistry (Online), Journal of biological chemistry, JBC online, JBC
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  • Material type
    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

American Society for Biochemistry and Molecular Biology

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    • Author cannot archive a pre-print version
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    • Author cannot archive a post-print version
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    • 12 months
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    • Authors accepted peer-reviewed manuscript may be posted on an institutional repository
    • Publisher copyright and source must be acknowledged with set phrase: "This research was originally published in Journal Name. Author(s). Title. Journal Name. Year. Vol:pp-pp. © the American Society for Biochemistry and Molecular Biology"
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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: The basic helix-loop-helix transcription factor hASH1, encoded by the ASCL1 gene, plays an important role in neurogenesis and tumor development. Recent findings indicate that the local oxygen tension is a critical determinant for the progression of neuroblastomas. Here we investigated the molecular mechanisms underlying the oxygen-dependent expression of hASH1 in neuroblastoma cells. Exposure of human neuroblastoma-derived Kelly cells to 1% O2 significantly decreased ASCL1 mRNA and hASH1 protein levels. Using reporter gene assays, we show that the response of hASH1 to hypoxia is mediated mainly by post-transcriptional inhibition via the ASCL1 mRNA 5’- and 3’-UTRs, while additional inhibition of the ASCL1 promoter was observed under prolonged hypoxia. By RNA pull-down experiments followed by MALDI/TOF-MS analysis, we identified heterogeneous nuclear ribonucleoprotein (hnRNP)-A2/B1 and hnRNP-R as interactors binding directly to the ASCL1 mRNA 5’- and 3’-UTRs and influencing its expression. We further demonstrate that hnRNP-A2/B1 is a key positive regulator of ASCL1, findings that were also confirmed by analysis of a large compilation of gene expression data. Our data suggest that a prominent downregulation of hnRNP-A2/B1 during hypoxia is associated with the post-transcriptional suppression of hASH1 synthesis. This novel post-transcriptional mechanism for regulating hASH1 levels will have important implications in neural cell fate development and disease.
    Journal of Biological Chemistry 08/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Collagen IV is a family of 6 chains (α1-α6), which form triple-helical protomers that assemble into supramolecular networks. Two distinct networks with chain compositions of α121 and α345 have been established. These oligomerize into separate α121 and α345 networks by a homotypic interaction through their trimeric noncollagenous (NC1) domains, forming α121 and α345 NC1-hexamers, respectively. These are stabilized by novel sulfilimine (-S=N-) crosslinks, a covalent crosslink that forms between Met93 and Hyl211. at the trimer-trimer interface. A third network with a composition of α1256 has been proposed, but its supramolecular organization has not been established. In this study, we investigated the supramolecular organization of this network by determining the chain identity of sulfilimine-crosslinked NC1 domains derived from the α1256 NC1 hexamer. High-resolution mass spectrometry analyses of peptides revealed that sulfilimine bonds specifically crosslink α1 to α5 and α2 to α6 NC1 domains, thus providing the spatial orientation between interacting α121 and α565 trimers. Using this information, we constructed a 3D homology model in which the α565 trimer shows a good chemical and structural complementarity to the α121 trimer. Our studies provide the first chemical evidence for an α565 protomer and its heterotypic interaction with the α121 protomer. Moreover, our findings, in conjunction with our previous studies, establish that the six collagen IV chains are organized into three canonical protomers α121, α345, and α565 forming three distinct networks: α121, α345 and α121-α565, each of which is stabilized by sulfilimine bonds between their C-terminal NC1 domains.
    Journal of Biological Chemistry 07/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The amyloid precursor protein (APP) and the APP-like proteins 1 and 2 (APLP1 and APLP2) are a family of multi-domain transmembrane proteins possessing homo- and heterotypic contact sites in their ectodomains. We previously reported that divalent metal ions dictate the conformation of the extracellular APP E2 domain (Dahms et al., 2012), but unresolved is the nature and functional importance of metal ion binding to APLP1 and APLP2. We presently found that zinc ions bound to APP and APLP1 E2 domains and mediated their oligomerization, whereas the APLP2 E2 domain interacted more weakly with zinc possessing a less surface-exposed zinc-binding site, and stayed monomeric. Copper ions bound to E2 domains of all three proteins. Fluorescence resonance energy transfer (FRET) analyses examined the effect of metal ion binding to APP and APLPs in the cellular context in real-time. Zinc ions specifically induced APP and APLP1 oligomerization and forced APLP1 into multimeric clusters at the plasma membrane consistent with zinc concentrations in the blood and brain. The observed effects were mediated by a novel zinc-binding site within the APLP1 E2 domain as APLP1 deletion mutants revealed. Based upon its cellular localization and its dominant response to zinc ions, APLP1 is mainly affected by extracellular zinc amongst the APP family proteins. We conclude that zinc-binding and APP/APLP oligomerization are intimately linked and propose this represents a novel mechanism for regulating APP/APLP protein function at the molecular level.
    Journal of Biological Chemistry 07/2014; 289(27):19019-19030.
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    ABSTRACT: Innate monocytes and macrophages can be dynamically programmed into distinct states depending upon the strength of external stimuli. Innate programming may bear significant relevance to the pathogenesis and resolution of human inflammatory diseases. However, systems analyses with regard to the dynamic programming of innate leukocytes are lacking. In this study, we focused on the dynamic responses of human promonocytic THP-1 cells to lipopolysaccharide (LPS). We observed that varying dosages of LPS differentially modulate the expression of selected pro- and anti- inflammatory mediators such as IL-6 and IL-33. Super-low dosages of LPS preferentially induced the pro-inflammatory mediator IL-6, while higher dosages of LPS induced both IL-6 and IL-33. Mechanistically, we demonstrated that super-low and high doses of LPS cause differential activation of GSK3 and Akt, as well as the transcription factors FoxO1 and CREB. Inhibition of GSK3 enabled THP-1 cells to express IL-33 when challenged with super-low dose LPS. On the other hand, activation of CREB with adenosine suppressed IL-6 expression. Taken together, our study reveals a dynamic modulation of monocytic cells in response to varying dosages of endotoxin, and may shed light on our understanding of the dynamic balance that controls pathogenesis and resolution of inflammatory diseases.
    Journal of Biological Chemistry 06/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Many cancer cells rely more on aerobic glycolysis (the Warburg effect) than mitochondrial oxidative phosphorylation and catabolize glucose at a high rate. Such a metabolic switch is suggested to be due in part to functional attenuation of mitochondria in cancer cells. However, how oncogenic signals attenuate mitochondrial function and promote the switch to glycolysis remains unclear. We previously reported that tyrosine phosphorylation activates and inhibits mitochondrial pyruvate dehydrogenase kinase (PDK) and phosphatase (PDP), respectively, leading to enhanced inhibitory serine phosphorylation of pyruvate dehydrogenase (PDH) and consequently inhibition of pyruvate dehydrogenase complex (PDC) in cancer cells. In particular, Y381 phosphorylation of PDP1 dissociates deacetylase SIRT3 and recruits acetyltransferase ACAT1 to PDC, resulting in increased inhibitory lysine acetylation of PDHA1 and PDP1. Here we report that phosphorylation at another tyrosine residue, Y94, inhibits PDP1 by reducing the binding ability of PDP1 to lipoic acid, which is covalently attached to the L2 domain of dihydrolipoyl acetyl-transferase (E2) to recruit PDP1 to PDC. We found that multiple oncogenic tyrosine kinases directly phosphorylated PDP1 at Y94, and Y94 phosphorylation of PDP1 was common in diverse human cancer cells and primary leukemia cells from patients. Moreover, expression of a phosphorylation-deficient PDP1 Y94F mutant in cancer cells resulted in increased oxidative phosphorylation, decreased cell proliferation under hypoxia, and reduced tumor growth in mice. Together, our findings suggest that phosphorylation at different tyrosine residues inhibits PDP1 through independent mechanisms, which act in concert to regulate PDC activity and promote the Warburg effect.
    Journal of Biological Chemistry 06/2014; jbc.M114.581124..
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    ABSTRACT: Translesion (TLS) DNA polymerases are specialized, error-prone enzymes that synthesize DNA across bulky, replication-stalling DNA adducts. In so doing, they facilitate the progression of DNA synthesis and promote cell proliferation. In order to potentiate the effect of cancer chemotherapeutic regimens, we sought to identify inhibitors of TLS DNA polymerases. We screened five libraries of ~3000 small molecules, including one comprising ~600 nucleoside analogs, for their effect on primer extension activity of DNA Polymerase η (Pol η). We serendipitously identified sphingosine, a lipid-signaling molecule that robustly stimulates the activity of Pol η by ~100-fold at low micromolar concentrations, but inhibits it at higher concentrations. This effect is specific to the Y-family DNA Polymerases, Pols -η, -κ, and -ι. The addition of a single phosphate group on sphingosine completely abrogates this effect. Likewise, the inclusion of other sphingolipids, including ceramide and sphingomyelin to extension reactions does not elicit this response. Sphingosine increases the rate of correct and incorrect nucleotide incorporation, while having no effect on polymerase processivity. Endogenous Pol η activity is modulated similarly as the recombinant enzyme. Importantly, sphingosine-treated cells exhibit increased lesion bypass activity, and sphingosine tethered to membrane lipids mimics the effects of free sphingosine. Our studies have uncovered sphingosine as a modulator of TLS DNA polymerase activity; this property of sphingosine may be associated with its known role as a signaling molecule in regulating cell proliferation in response to cellular stress.
    Journal of Biological Chemistry 06/2014;
  • Journal of Biological Chemistry 06/2014; 289:16526.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The lymphatic system plays an important role in cancer metastasis and inhibition of lymphangiogenesis could be valuable in fighting cancer dissemination. Podoplanin (Pdpn) is a small, transmembrane glycoprotein expressed on the surface of lymphatic endothelial cells (LEC). During mouse development, binding of Pdpn to the C-type lectin-like receptor 2 (CLEC-2) on platelets is critical for the separation of the lymphatic and blood vascular systems. Competitive inhibition of Pdpn functions with a soluble form of the protein, Pdpn-Fc, leads to reduced lymphangiogenesis in vitro and in vivo. However, the transgenic overexpression of human Pdpn-Fc in mouse skin causes disseminated intravascular coagulation (DIC) due to platelet activation via CLEC-2. In the present study, we produced and characterized a mutant form of mouse Pdpn-Fc, in which threonin 34, which is considered essential for CLEC-2 binding, was mutated to alanine (PdpnT34A-Fc). Indeed, PdpnT34A-Fc displayed a 30-fold reduced binding affinity for CLEC-2 compared to Pdpn-Fc. This also translated into fewer side effects due to platelet activation in vivo. Mice showed less prolonged bleeding time and fewer embolized vessels in the liver, when PdpnT34A-Fc was injected intravenously. However, PdpnT34A-Fc was still as active as wild-type Pdpn-Fc in inhibiting lymphangiogenesis in vitro and also inhibited lymphangiogenesis in vivo. These data suggest that the function of Pdpn in lymphangiogenesis does not depend on threonine 34 in the CLEC-2 binding domain and that PdpnT34A-Fc might be an improved inhibitor of lymphangiogenesis with fewer toxic side effects.
    Journal of Biological Chemistry 06/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: New antiviral agents bind to a site on HIV integrase protein also bound by the cellular protein LEDGF/p75. Results: Compound GSK1264 binds to this site, but has surprising properties—it inhibits late during HIV replication, not early during integration, and it promotes abnormal multimerization. Conclusion: GSK1264 provides new insight into HIV replication. Significance: These observations inform the design of improved antiviral agents
    Journal of Biological Chemistry 06/2014;