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  • Life Sciences (General)  (7)
  • Cell Cycle  (1)
  • Cyclin-Dependent Kinase Inhibitor p16/deficiency/genetics/metabolism  (1)
  • 1
    Publication Date: 2013-02-05
    Description: Cancer control by adaptive immunity involves a number of defined death and clearance mechanisms. However, efficient inhibition of exponential cancer growth by T cells and interferon-gamma (IFN-gamma) requires additional undefined mechanisms that arrest cancer cell proliferation. Here we show that the combined action of the T-helper-1-cell cytokines IFN-gamma and tumour necrosis factor (TNF) directly induces permanent growth arrest in cancers. To safely separate senescence induced by tumour immunity from oncogene-induced senescence, we used a mouse model in which the Simian virus 40 large T antigen (Tag) expressed under the control of the rat insulin promoter creates tumours by attenuating p53- and Rb-mediated cell cycle control. When combined, IFN-gamma and TNF drive Tag-expressing cancers into senescence by inducing permanent growth arrest in G1/G0, activation of p16INK4a (also known as CDKN2A), and downstream Rb hypophosphorylation at serine 795. This cytokine-induced senescence strictly requires STAT1 and TNFR1 (also known as TNFRSF1A) signalling in addition to p16INK4a. In vivo, Tag-specific T-helper 1 cells permanently arrest Tag-expressing cancers by inducing IFN-gamma- and TNFR1-dependent senescence. Conversely, Tnfr1(-/-)Tag-expressing cancers resist cytokine-induced senescence and grow aggressively, even in TNFR1-expressing hosts. Finally, as IFN-gamma and TNF induce senescence in numerous murine and human cancers, this may be a general mechanism for arresting cancer progression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Braumuller, Heidi -- Wieder, Thomas -- Brenner, Ellen -- Assmann, Sonja -- Hahn, Matthias -- Alkhaled, Mohammed -- Schilbach, Karin -- Essmann, Frank -- Kneilling, Manfred -- Griessinger, Christoph -- Ranta, Felicia -- Ullrich, Susanne -- Mocikat, Ralph -- Braungart, Kilian -- Mehra, Tarun -- Fehrenbacher, Birgit -- Berdel, Julia -- Niessner, Heike -- Meier, Friedegund -- van den Broek, Maries -- Haring, Hans-Ulrich -- Handgretinger, Rupert -- Quintanilla-Martinez, Leticia -- Fend, Falko -- Pesic, Marina -- Bauer, Jurgen -- Zender, Lars -- Schaller, Martin -- Schulze-Osthoff, Klaus -- Rocken, Martin -- England -- Nature. 2013 Feb 21;494(7437):361-5. doi: 10.1038/nature11824. Epub 2013 Feb 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Dermatology, Eberhard Karls University, Liebermeister Strasse 25, 72076 Tubingen, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23376950" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Polyomavirus Transforming/genetics/metabolism ; Cell Aging/*immunology ; Cell Cycle ; Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor p16/deficiency/genetics/metabolism ; Cytokines/*immunology ; Disease Models, Animal ; Disease Progression ; Female ; Humans ; Interferon-gamma/immunology ; Male ; Mice ; Mice, Inbred NOD ; Mice, SCID ; Mice, Transgenic ; Neoplasms/*immunology/*pathology ; Oncogenes/genetics ; Phosphoserine/metabolism ; Receptors, Tumor Necrosis Factor, Type I/metabolism ; Retinoblastoma Protein/chemistry/metabolism ; STAT1 Transcription Factor/metabolism ; Th1 Cells/*immunology ; Time Factors ; Tumor Cells, Cultured ; Tumor Necrosis Factor-alpha/immunology ; Tumor Suppressor Protein p53/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2011-08-24
    Description: Recently developed molecular and genetic approaches have enabled the identification and functional characterization of novel genes encoding ion channels, ion carriers, and water channels of the plant plasma membrane.
    Keywords: Life Sciences (General)
    Type: Current opinion in cell biology (ISSN 0955-0674); Volume 8; 4; 458-67
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  • 3
    Publication Date: 2011-08-24
    Description: Laser microsurgery can be used to perform both cell biological manipulations, such as targeted cell ablation, and molecular genetic manipulations, such as genetic transformation and chromosome dissection. In this report, we describe a laser microsurgical method that can be used either to ablate single cells or to ablate a small area (1-3 microns diameter) of the extracellular matrix. In plants and microorganisms, the extracellular matrix consists of the cell wall. While conventional patch clamping of these cells, as well as of many animal cells, requires enzymatic digestion of the extracellular matrix, we illustrate that laser microsurgery of a portion of the wall enables patch clamp access to the plasma membrane of higher plant cells remaining situated in their tissue environment. What follows is a detailed description of the construction and use of an economical laser microsurgery system, including procedures for single cell and targeted cell wall ablation. This methodology will be of interest to scientists wishing to perform cellular or subcellular ablation with a high degree of accuracy, or wishing to study how the extracellular matrix affects ion channel function.
    Keywords: Life Sciences (General)
    Type: Pflugers Archiv : European journal of physiology (ISSN 0031-6768); Volume 433; 6; 832-41
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  • 4
    Publication Date: 2011-08-24
    Description: No abstract available
    Keywords: Life Sciences (General)
    Type: Methods in enzymology (ISSN 0076-6879); Volume 294; 410-41
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  • 5
    Publication Date: 2011-08-24
    Description: Regulation of guard cell ion transport by abscisic acid (ABA) and in particular ABA inhibition of a guard cell inward K(+) current (I(Kin)) is well documented. However, little is known concerning ABA effects on ion transport in other plant cell types. Here we applied patch clamp techniques to mesophyll cell protoplasts of fava bean (Vicia faba cv Long Pod) plants and demonstrated ABA inhibition of an outward K(+) current (I(Kout)). When mesophyll cell protoplast mRNA (mesophyll mRNA) was expressed in Xenopus laevis oocytes, I(Kout) was generated that displayed similar properties to I(Kout) observed from direct analysis of mesophyll cell protoplasts. I(Kout) expressed by mesophyll mRNA-injected oocytes was inhibited by ABA, indicating that the ABA signal transduction pathway observed in mesophyll cells was preserved in the frog oocytes. Co-injection of oocytes with guard cell protoplast mRNA and cRNA for KAT1, an inward K(+) channel expressed in guard cells, resulted in I(Kin) that was similarly inhibited by ABA. However, oocytes co-injected with mesophyll mRNA and KAT1 cRNA produced I(Kin) that was not inhibited by ABA. These results demonstrate that the mesophyll-encoded signaling mechanism could not substitute for the guard cell pathway. These findings indicate that mesophyll cells and guard cells use distinct and different receptor types and/or signal transduction pathways in ABA regulation of K(+) channels.
    Keywords: Life Sciences (General)
    Type: Plant physiology (ISSN 0032-0889); Volume 124; 1; 223-30
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  • 6
    Publication Date: 2019-08-16
    Description: The distribution of calmodulin (CaM) and CaM-binding proteins within Vicia faba was investigated. Both CaM and CaM-binding proteins were found to be differentially distributed among organs, tissues, and protoplast types. CaM levels, on a per protein basis, were found to be the highest in leaf epidermis, containing 3-fold higher levels of CaM than in total leaf. Similarly, guard cell and epidermal cell protoplasts were also found to have higher levels of CaM than mesophyll cell protoplasts. 125I-CaM blot overlay assays were performed to qualitatively examine CaM-binding proteins in these protoplast types as well as in whole tissues and organs. CaM-binding proteins with Mr 52,000, 78,000, and 115,000 were common in all metabolically active plant parts. Unique CaM-binding protein bands were detected in guard cell protoplasts (Mr 39,000, 88,000), stems (Mr 45,000, 60,000, 64,000), and roots (Mr 62,000), suggesting the presence of specialized CaM-dependent processes in these cells and organs.
    Keywords: Life Sciences (General)
    Type: Plant physiology (ISSN 0032-0889); 100; 970-8
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  • 7
    Publication Date: 2019-07-13
    Description: Plasma membranes of guard cells in epidermal peels of Vicia faba and Commelina communis can be made accessible to a patch-clamp pipet by removing a small portion (1-3 micrometers in diameter) of the guard cell wall using a microbeam of ultraviolet light generated by a nitrogen laser. Using this laser microsurgical technique, we have measured channel activity across plasma membranes of V. faba guard cells in both cell-attached and isolated patch configurations. Measurements made in the inside-out patch configuration revealed two distinct K(+)-selective channels. Major advantages of the laser microsurgical technique include the avoidance of enzymatic protoplast isolation, the ability to study cell types that have been difficult to isolate as protoplasts or for which enzymatic isolation protocols result in protoplasts not amenable to patch-clamp studies, the maintenance of positional information in single-channel measurements, reduced disruption of cell-wall-mediated signaling pathways, and the ability to investigate intercellular signaling through studies of cells remaining situated within tissue.
    Keywords: Life Sciences (General)
    Type: Plant physiology (ISSN 0032-0889); 110; 1063-8
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  • 8
    Publication Date: 2019-07-13
    Description: Application of patch clamp techniques to higher-plant cells has been subject to the limitation that the requisite contact of the patch electrode with the cell membrane necessitates prior enzymatic removal of the plant cell wall. Because the wall is an integral component of plant cells, and because cell-wall-degrading enzymes can disrupt membrane properties, such enzymatic treatments may alter ion channel behavior. We compared ion channel activity in enzymatically isolated protoplasts of Vicia faba guard cells with that found in membranes exposed by a laser microsurgical technique in which only a tiny portion of the cell wall is removed while the rest of the cell remains intact within its tissue environment. "Laser-assisted" patch clamping reveals a new category of high-conductance (130 to 361 pS) ion channels not previously reported in patch clamp studies on plant plasma membranes. These data indicate that ion channels are present in plant membranes that are not detected by conventional patch clamp techniques involving the production of individual plant protoplasts isolated from their tissue environment by enzymatic digestion of the cell wall. Given the large conductances of the channels revealed by laser-assisted patch clamping, we hypothesize that these channels play a significant role in the regulation of ion content and electrical signalling in guard cells.
    Keywords: Life Sciences (General)
    Type: Protoplasma (ISSN 0033-183X); 209; 2-Jan; 58-67
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