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  • Proceedings of the National Academy of Sciences  (9)
  • 2005-2009  (9)
  • Biodiversity Research  (9)
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  • Proceedings of the National Academy of Sciences  (9)
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  • 2005-2009  (9)
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Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    The GTPase Rab3b/3c-positive recycling vesicles are involved in cross-presentation in dendritic cells
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 37 ( 2009-09-15), p. 15801-15806
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 37 ( 2009-09-15), p. 15801-15806
    Abstract: Antigen cross-presentation in dendritic cells is a complex intracellular membrane transport process, but the underlying molecular mechanisms remain to be thoroughly investigated. In this study, we examined the effect of siRNA-mediated knockdown of 57 Rab GTPases, the key regulators of membrane trafficking, on antigen cross-presentation. Twelve Rab GTPases were identified to be associated with antigen cross-presentation, and Rab3b/3c was indicated to be colocalized with MHC class I molecules at perinuclear tubular structure. Tracing with fluorescence protein-tagged β 2 -microglobulin demonstrated that the MHC class I molecules were internalized from the plasma membrane to Rab3b/3c-positive compartments, which were also colocalized with the internalized transferrin. Moreover, depletion of Rab3b/3c strongly reduced the fast phase recycling rate of transferrin receptors. Furthermore, the Rab3b/3c-positive compartments were colocalized with a fraction of Rab27a at a juxtaposition of phagosomes. Together, these data demonstrate that Rab3b/3c-positive recycling vesicles are involved in and may constitute one of the recycling compartments in exogenous antigen cross-presentation.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0905684106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    A pivotal role for endogenous TGF-β-activated kinase-1 in the LKB1/AMP-activated protein kinase energy-sensor pathway
    Proceedings of the National Academy of Sciences ; 2006
    In:  Proceedings of the National Academy of Sciences Vol. 103, No. 46 ( 2006-11-14), p. 17378-17383
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 103, No. 46 ( 2006-11-14), p. 17378-17383
    Abstract: TGF-β-activated kinase-1 (TAK1), also known as MAPKK kinase-7 (MAP3K7), is a candidate effector of multiple circuits in cardiac biology and disease. Here, we show that inhibition of TAK1 in mice by a cardiac-specific dominant-negative mutation evokes electrophysiological and biochemical properties reminiscent of human Wolff–Parkinson–White syndrome, arising from mutations in AMP-activated protein kinase (AMPK), most notably, accelerated atrioventricular conduction and impaired AMPK activation. To test conclusively the biochemical connection from TAK1 to AMPK suggested by this phenotype, we disrupted TAK1 in mouse embryos and embryonic fibroblasts by Cre-mediated recombination. In TAK1-null embryos, the activating phosphorylation of AMPK at T172 was blocked, accompanied by defective AMPK activity. However, loss of endogenous TAK1 causes midgestation lethality, with defective yolk sac and intraembryonic vasculature. To preclude confounding lethal defects, we acutely ablated floxed TAK1 in culture by viral delivery of Cre. In culture, endogenous TAK1 was activated by oligomycin, the antidiabetic drug metformin, 5-aminoimidazole-4-carboxamide riboside (AICAR), and ischemia, well established triggers of AMPK activity. Loss of TAK1 in culture blocked T172 phosphorylation induced by all three agents, interfered with AMPK activation, impaired phosphorylation of the endogenous AMPK substrate acetyl CoA carboxylase, and also interfered with activation of the AMPK kinase LKB1. Thus, by disrupting the endogenous TAK1 locus, we prove a pivotal role for TAK1 in the LKB1/AMPK signaling axis, an essential governor of cell metabolism.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0604708103
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2006
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Microtubule-binding drugs offset tau sequestration by stabilizing microtubules and reversing fast axonal transport deficits in a tauopathy model
    Proceedings of the National Academy of Sciences ; 2005
    In:  Proceedings of the National Academy of Sciences Vol. 102, No. 1 ( 2005-01-04), p. 227-231
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 102, No. 1 ( 2005-01-04), p. 227-231
    Abstract: We tested the hypothesis that microtubule (MT)-binding drugs could be therapeutically beneficial in tauopathies by functionally substituting for the MT-binding protein tau, which is sequestered into inclusions of human tauopathies and transgenic mouse models thereof. Transgenic mice were treated for 12 weeks with weekly i.p. injections of 10 or 25 mg/m 2 paclitaxel (Paxceed). Both doses restored fast axonal transport in spinal axons, wherein MT numbers and stable (detyrosinated) tubulins were increased, compared with sham treatment, and only Paxceed ameliorated motor impairments in tau transgenic mice. Thus, MT-stabilizing drugs could have therapeutic potential for treating neurodegenerative tauopathies by offsetting losses of tau function that result from the sequestration of this MT-stabilizing protein into filamentous inclusions.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0406361102
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2005
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Mice expressing a humanized form of VEGF-A may provide insights into the safety and efficacy of anti-VEGF antibodies
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 9 ( 2007-02-27), p. 3478-3483
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 9 ( 2007-02-27), p. 3478-3483
    Abstract: VEGF-A is important in tumor angiogenesis, and a humanized anti-VEGF-A monoclonal antibody (bevacizumab) has been approved by the FDA as a treatment for metastatic colorectal and nonsquamous, non-small-cell lung cancer in combination with chemotherapy. However, contributions of both tumor- and stromal-cell derived VEGF-A to vascularization of human tumors grown in immunodeficient mice hindered direct comparison between the pharmacological effects of anti-VEGF antibodies with different abilities to block host VEGF. Therefore, by gene replacement technology, we engineered mice to express a humanized form of VEGF-A (hum-X VEGF) that is recognized by many anti-VEGF antibodies and has biochemical and biological properties comparable with WT mouse and human VEGF-A. The hum-X VEGF mouse model was then used to compare the activity and safety of a panel of VEGF Mabs with different affinities for VEGF-A. Although in vitro studies clearly showed a correlation between binding affinity and potency at blocking endothelial cell proliferation stimulated by VEGF, in vivo experiments failed to document any consistent correlation between antibody affinity and the ability to inhibit tumor growth and angiogenesis in most animal models. However, higher-affinity antibodies were more likely to result in glomerulosclerosis during long-term treatment.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0611492104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Proliferation and invasion: Plasticity in tumor cells
    Proceedings of the National Academy of Sciences ; 2005
    In:  Proceedings of the National Academy of Sciences Vol. 102, No. 30 ( 2005-07-26), p. 10528-10533
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 102, No. 30 ( 2005-07-26), p. 10528-10533
    Abstract: Invasive and proliferative phenotypes are fundamental components of malignant disease, yet basic questions persist about whether tumor cells can express both phenotypes simultaneously and, if so, what are their properties. Suitable in vitro models that allow characterization of cells that are purely invasive are limited because proliferation is required for cell maintenance. Here, we describe glioblastoma cells that are highly invasive in response to hepatocyte growth factor/scatter factor (HGF/SF). From this cell population, we selected subclones that were highly proliferative or displayed both invasive and proliferative phenotypes. The biological activities of invasion, migration, urokinase-type plasminogen activation, and branching morphogenesis exclusively partitioned with the highly invasive cells, whereas the highly proliferative subcloned cells uniquely displayed anchorage independent growth in soft agar and were highly tumorigenic as xenografts in immune-compromised mice. In response to HGF/SF, the highly invasive cells signal through the MAPK pathway, whereas the selection of the highly proliferative cells coselected for signaling through Myc. Moreover, in subcloned cells displaying both invasive and proliferative phenotypes, both signaling pathways are activated by HGF/SF. These results show how the mitogen-activated protein kinase and Myc pathways can cooperate to confer both invasive and proliferative phenotypes on tumor cells and provide a system for studying how transitions between invasion and proliferation can contribute to malignant progression.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0504367102
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2005
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 6
    Online Resource
    Online Resource
    The histone gene activator HINFP is a nonredundant cyclin E/CDK2 effector during early embryonic cell cycles
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 30 ( 2009-07-28), p. 12359-12364
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 30 ( 2009-07-28), p. 12359-12364
    Abstract: Competency for DNA replication is functionally coupled to the activation of histone gene expression at the onset of S phase to form chromatin. Human histone nuclear factor P (HiNF-P; gene symbol HINFP ) bound to its cyclin E/cyclin-dependent kinase 2 (CDK2) responsive coactivator p220 NPAT is a key regulator of multiple human histone H4 genes that encode a major subunit of the nucleosome. Induction of the histone H4 transcription factor (HINFP)/p220 NPAT coactivation complex occurs in parallel with the CDK-dependent release of pRB from E2F at the restriction point. Here, we show that the downstream CDK-dependent cell cycle effector HINFP is genetically required and, in contrast to the CDK2/cyclin E complex, cannot be compensated. We constructed a mouse Hinfp -null mutation and found that heterozygous Hinfp mice survive, indicating that 1 allele suffices for embryogenesis. Homozygous loss-of-function causes embryonic lethality: No homozygous Hinfp -null mice are obtained at or beyond embryonic day (E) 6.5. In blastocyst cultures, Hinfp -null embryos exhibit a delay in hatching, abnormal growth, and loss of histone H4 gene expression. Our data indicate that the CDK2 / cyclin E / p220 NPAT / HINFP / histone gene signaling pathway at the G1/S phase transition is an essential, nonredundant cell cycle regulatory mechanism that is established early in embryogenesis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0905651106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 7
    Online Resource
    Online Resource
    Mechanism for alternating access in neurotransmitter transporters
    Proceedings of the National Academy of Sciences ; 2008
    In:  Proceedings of the National Academy of Sciences Vol. 105, No. 30 ( 2008-07-29), p. 10338-10343
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 105, No. 30 ( 2008-07-29), p. 10338-10343
    Abstract: Crystal structures of LeuT, a bacterial homologue of mammalian neurotransmitter transporters, show a molecule of bound substrate that is essentially exposed to the extracellular space but occluded from the cytoplasm. Thus, there must exist an alternate conformation for LeuT in which the substrate is accessible to the cytoplasm and a corresponding mechanism that switches accessibility from one side of the membrane to the other. Here, we identify the cytoplasmic accessibility pathway of the alternate conformation in a mammalian serotonin transporter (SERT) (a member of the same transporter family as LeuT). We also propose a model for the cytoplasmic-facing state that exploits the internal pseudosymmetry observed in the crystal structure. LeuT contains two structurally similar repeats (TMs1–5 and TMs 6–10) that are inverted with respect to the plane of the membrane. The conformational differences between them result in the formation of the extracellular pathway. Our model for the cytoplasm-facing state exchanges the conformations of the two repeats and thus exposes the substrate and ion-binding sites to the cytoplasm. The conformational change that connects the two states primarily involves the tilting of a 4-helix bundle composed of transmembrane helices 1, 2, 6, and 7. Switching the tilt angle of this bundle is essentially equivalent to switching the conformation of the two repeats. Extensive mutagenesis of SERT and accessibility measurements, using cysteine reagents, are accommodated by our model. These observations may be of relevance to other transporter families, many of which contain internal inverted repeats.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0804659105
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2008
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 8
    Online Resource
    Online Resource
    C-terminal peptides coassemble into Aβ42 oligomers and protect neurons against Aβ42-induced neurotoxicity
    Proceedings of the National Academy of Sciences ; 2008
    In:  Proceedings of the National Academy of Sciences Vol. 105, No. 37 ( 2008-09-16), p. 14175-14180
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 105, No. 37 ( 2008-09-16), p. 14175-14180
    Abstract: Alzheimer's disease (AD) is an age-related disorder that threatens to become an epidemic as the world population ages. Neurotoxic oligomers of Aβ42 are believed to be the main cause of AD; therefore, disruption of Aβ oligomerization is a promising approach for developing therapeutics for AD. Formation of Aβ42 oligomers is mediated by intermolecular interactions in which the C terminus plays a central role. We hypothesized that peptides derived from the C terminus of Aβ42 may get incorporated into oligomers of Aβ42, disrupt their structure, and thereby inhibit their toxicity. We tested this hypothesis using Aβ fragments with the general formula Aβ( x −42) ( x = 28–39). A cell viability screen identified Aβ(31–42) as the most potent inhibitor. In addition, the shortest peptide, Aβ(39–42), also had high activity. Both Aβ(31–42) and Aβ(39–42) inhibited Aβ-induced cell death and rescued disruption of synaptic activity by Aβ42 oligomers at micromolar concentrations. Biophysical characterization indicated that the action of these peptides likely involved stabilization of Aβ42 in nontoxic oligomers. Computer simulations suggested a mechanism by which the fragments coassembled with Aβ42 to form heterooligomers. Thus, Aβ(31–42) and Aβ(39–42) are leads for obtaining mechanism-based drugs for treatment of AD using a systematic structure–activity approach.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0807163105
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2008
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 9
    Online Resource
    Online Resource
    A nonpeptidic agonist of glucagon-like peptide 1 receptors with efficacy in diabetic db / db mice
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 3 ( 2007-01-16), p. 943-948
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 3 ( 2007-01-16), p. 943-948
    Abstract: Peptidic mimics of the gut hormone glucagon-like peptide (GLP) 1, exemplified by the recently approved drug exenatide, show promise as therapies for type 2 diabetes. Such “incretin mimetics” regulate glucose appearance in the plasma and can restore glucose-stimulated insulin secretion without excess risk of hypoglycemia. The need for injection, which may limit the use of peptidic GLP-1 receptor (GLP-1R) agonists, has driven largely unsuccessful efforts to find smaller molecules. The failure to identify orally effective agonists has instead promoted the indirect approach of inhibiting the GLP-1-degrading enzyme dipeptidyl peptidase IV. Here we report a nonpeptidic GLP-1R agonist with sufficient activity to evoke effects in whole animals, including antidiabetic efficacy in db / db mice. Two substituted cyclobutanes (S4P and Boc5) were developed after screening a compound library against a cell line stably cotransfected with GLP-1R and a cAMP-responsive reporter. Each bound to GLP-1R and increased intracellular cAMP. Agonist effects were blocked by the GLP-1R antagonist exendin(9–39). Boc5 amplified glucose-stimulated insulin secretion in isolated rat islets. Both i.p. and oral administration of Boc5 dose-dependently inhibited food intake in mice, an effect that could be blocked by pretreatment with exendin(9–39). Daily injections of Boc5 into db / db mice reduced HbA1c to nondiabetic values, an effect not observed in ad libitum-fed or pair-fed diabetic controls. Thus, Boc5 behaved as a full GLP-1 mimetic in vitro and in vivo . The chemical genus represented by Boc5 may prompt the exploration of orally available GLP-1R agonists with potential utility in diabetes and obesity.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0610173104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
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