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  1. Article ; Online: Rho and Rab Family Small GTPases in the Regulation of Membrane Polarity in Epithelial Cells

    Klaus Ebnet / Volker Gerke

    Frontiers in Cell and Developmental Biology, Vol

    2022  Volume 10

    Abstract: Membrane polarity, defined as the asymmetric distribution of lipids and proteins in the plasma membrane, is a critical prerequisite for the development of multicellular tissues, such as epithelia and endothelia. Membrane polarity is regulated by ... ...

    Abstract Membrane polarity, defined as the asymmetric distribution of lipids and proteins in the plasma membrane, is a critical prerequisite for the development of multicellular tissues, such as epithelia and endothelia. Membrane polarity is regulated by polarized trafficking of membrane components to specific membrane domains and requires the presence of intramembrane diffusion barriers that prevent the intermixing of asymmetrically distributed membrane components. This intramembrane diffusion barrier is localized at the tight junctions (TJs) in these cells. Both the formation of cell-cell junctions and the polarized traffic of membrane proteins and lipids are regulated by Rho and Rab family small GTPases. In this review article, we will summarize the recent developments in the regulation of apico-basal membrane polarity by polarized membrane traffic and the formation of the intramembrane diffusion barrier in epithelial cells with a particular focus on the role of Rho and Rab family small GTPases.
    Keywords apico-basal membrane polarity ; Rab small GTPase ; Rho small GTPase ; tight junctions ; vesicle transport ; Biology (General) ; QH301-705.5
    Subject code 571
    Language English
    Publishing date 2022-07-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Acidification of endothelial Weibel-Palade bodies is mediated by the vacuolar-type H+-ATPase.

    Julian Terglane / Dirk Menche / Volker Gerke

    PLoS ONE, Vol 17, Iss 6, p e

    2022  Volume 0270299

    Abstract: Weibel-Palade bodies (WPB) are unique secretory granules of endothelial cells that store the procoagulant von-Willebrand factor (VWF) in a highly compacted form. Upon exocytosis the densely packed VWF unfurls into long strands that expose binding sites ... ...

    Abstract Weibel-Palade bodies (WPB) are unique secretory granules of endothelial cells that store the procoagulant von-Willebrand factor (VWF) in a highly compacted form. Upon exocytosis the densely packed VWF unfurls into long strands that expose binding sites for circulating platelets and thereby initiate the formation of a platelet plug at sites of blood vessel injury. Dense packing of VWF requires the establishment of an acidic pH in the lumen of maturing WPB but the mechanism responsible for this acidification has not yet been fully established. We show here that subunits of the vacuolar-type H+-ATPase are present on mature WPB and that interference with the proton pump activity of the ATPase employing inhibitors of different chemical nature blocks a reduction in the relative internal pH of WPB. Furthermore, depletion of the V-ATPase subunit V0d1 from primary endothelial cells prevents WPB pH reduction and the establishment of an elongated morphology of WPB that is dictated by the densely packed VWF tubules. Thus, the vacuolar-type H+-ATPase present on WPB is required for proper acidification and maturation of the organelle.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2022-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Weibel Palade Bodies

    Johannes Naß / Julian Terglane / Volker Gerke

    Frontiers in Cell and Developmental Biology, Vol

    Unique Secretory Organelles of Endothelial Cells that Control Blood Vessel Homeostasis

    2021  Volume 9

    Abstract: Vascular endothelial cells produce and release compounds regulating vascular tone, blood vessel growth and differentiation, plasma composition, coagulation and fibrinolysis, and also engage in interactions with blood cells thereby controlling hemostasis ... ...

    Abstract Vascular endothelial cells produce and release compounds regulating vascular tone, blood vessel growth and differentiation, plasma composition, coagulation and fibrinolysis, and also engage in interactions with blood cells thereby controlling hemostasis and acute inflammatory reactions. These interactions have to be tightly regulated to guarantee smooth blood flow in normal physiology, but also allow specific and often local responses to blood vessel injury and infectious or inflammatory insults. To cope with these challenges, endothelial cells have the remarkable capability of rapidly changing their surface properties from non-adhesive (supporting unrestricted blood flow) to adhesive (capturing circulating blood cells). This is brought about by the evoked secretion of major adhesion receptors for platelets (von-Willebrand factor, VWF) and leukocytes (P-selectin) which are stored in a ready-to-be-used form in specialized secretory granules, the Weibel-Palade bodies (WPB). WPB are unique, lysosome related organelles that form at the trans-Golgi network and further mature by receiving material from the endolysosomal system. Failure to produce correctly matured VWF and release it through regulated WPB exocytosis results in pathologies, most importantly von-Willebrand disease, the most common inherited blood clotting disorder. The biogenesis of WPB, their intracellular motility and their fusion with the plasma membrane are regulated by a complex interplay of proteins and lipids, involving Rab proteins and their effectors, cytoskeletal components as well as membrane tethering and fusion machineries. This review will discuss aspects of WPB biogenesis, trafficking and exocytosis focussing on recent findings describing factors contributing to WPB maturation, WPB-actin interactions and WPB-plasma membrane tethering and fusion.
    Keywords calcium ; exocytosis ; lysosome-related organelle ; secretory organelles ; hemostasis ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2021-12-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Special Issue “Recent Developments in Annexin Biology”

    Ursula Rescher / Volker Gerke / Lina Hsiu Kim Lim / Jyoti K. Jaiswal

    Cells, Vol 9, Iss 2477, p

    2020  Volume 2477

    Abstract: Discovered over 40 years ago, the annexin proteins were found to be a structurally conserved subgroup of Ca 2+ -binding proteins. While the initial research on annexins focused on their signature feature of Ca 2+ -dependent binding to membranes, over the ...

    Abstract Discovered over 40 years ago, the annexin proteins were found to be a structurally conserved subgroup of Ca 2+ -binding proteins. While the initial research on annexins focused on their signature feature of Ca 2+ -dependent binding to membranes, over the years the biennial Annexin conference series has highlighted additional diversity in the functions attributed to the annexin family of proteins. The roles of these proteins now extend from basic science to biomedical research, and are being translated into the clinic. The research on annexins involves a global network of researchers, and the 10th biennial Annexin conference brought together over 80 researchers from ten European countries, USA, Brazil, Singapore, Japan and Australia for 3 days in September 2019. In this conference, the discussions focused on two distinct themes—the role of annexins in cellular organization and in health and disease. The articles published in this Special Issue cover these two main themes discussed at this conference, offering a glimpse into some of the notable findings in the field of annexin biology.
    Keywords Annexin ; inflammation ; membrane ; injury ; exocytosis ; membrane repair ; Biology (General) ; QH301-705.5
    Subject code 333
    Language English
    Publishing date 2020-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Exploring Biased Agonism at FPR1 as a Means to Encode Danger Sensing

    Jieny Gröper / Gabriele M. König / Evi Kostenis / Volker Gerke / Carsten A. Raabe / Ursula Rescher

    Cells, Vol 9, Iss 1054, p

    2020  Volume 1054

    Abstract: Ligand-based selectivity in signal transduction (biased signaling) is an emerging field of G protein-coupled receptor (GPCR) research and might allow the development of drugs with targeted activation profiles. Human formyl peptide receptor 1 (FPR1) is a ... ...

    Abstract Ligand-based selectivity in signal transduction (biased signaling) is an emerging field of G protein-coupled receptor (GPCR) research and might allow the development of drugs with targeted activation profiles. Human formyl peptide receptor 1 (FPR1) is a GPCR that detects potentially hazardous states characterized by the appearance of N-formylated peptides that originate from either bacteria or mitochondria during tissue destruction; however, the receptor also responds to several non-formylated agonists from various sources. We hypothesized that an additional layer of FPR signaling is encoded by biased agonism, thus allowing the discrimination of the source of threat. We resorted to the comparative analysis of FPR1 agonist-evoked responses across three prototypical GPCR signaling pathways, i.e., the inhibition of cAMP formation, receptor internalization, and ERK activation, and analyzed cellular responses elicited by several bacteria- and mitochondria-derived ligands. We also included the anti-inflammatory annexinA1 peptide Ac2-26 and two synthetic ligands, the W-peptide and the small molecule FPRA14. Compared to the endogenous agonists, the bacterial agonists displayed significantly higher potencies and efficacies. Selective pathway activation was not observed, as both groups were similarly biased towards the inhibition of cAMP formation. The general agonist bias in FPR1 signaling suggests a source-independent pathway selectivity for transmission of pro-inflammatory danger signaling.
    Keywords bias analysis ; G protein-coupled receptor (GPCR) ; formyl peptide receptor 1 ; danger-associated molecular pattern (DAMP) ; pathogen-associated molecular pattern (PAMP) ; annexin A1 peptide Ac2-26 ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2020-04-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Modeling of annexin A2-Membrane interactions by molecular dynamics simulations.

    Davit Hakobyan / Volker Gerke / Andreas Heuer

    PLoS ONE, Vol 12, Iss 9, p e

    2017  Volume 0185440

    Abstract: The annexins are a family of Ca2+-regulated phospholipid binding proteins that are involved in membrane domain organization and membrane trafficking. Although they are widely studied and crystal structures are available for several soluble annexins their ...

    Abstract The annexins are a family of Ca2+-regulated phospholipid binding proteins that are involved in membrane domain organization and membrane trafficking. Although they are widely studied and crystal structures are available for several soluble annexins their mode of membrane association has never been studied at the molecular level. Here we obtained molecular information on the annexin-membrane interaction that could serve as paradigm for the peripheral membrane association of cytosolic proteins by Molecular Dynamics simulations. We analyzed systems containing the monomeric annexin A2 (AnxA2), a membrane with negatively charged phosphatidylserine (POPS) lipids as well as Ca2+ ions. On the atomic level we identify the AnxA2 orientations and the respective residues which display the strongest interaction with Ca2+ ions and the membrane. The simulation results fully agree with earlier experimental findings concerning the positioning of bound Ca2+ ions. Furthermore, we identify for the first time a significant interaction between lysine residues of the protein and POPS lipids that occurs independently of Ca2+ suggesting that AnxA2-membrane interactions can also occur in a low Ca2+ environment. Finally, by varying Ca2+ concentrations and lipid composition in our simulations we observe a calcium-induced negative curvature of the membrane as well as an AnxA2-induced lipid ordering.
    Keywords Medicine ; R ; Science ; Q
    Subject code 612
    Language English
    Publishing date 2017-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Membrane recruitment of the polarity protein Scribble by the cell adhesion receptor TMIGD1

    Eva-Maria Thüring / Christian Hartmann / Janesha C. Maddumage / Airah Javorsky / Birgitta E. Michels / Volker Gerke / Lawrence Banks / Patrick O. Humbert / Marc Kvansakul / Klaus Ebnet

    Communications Biology, Vol 6, Iss 1, Pp 1-

    2023  Volume 15

    Abstract: Abstract Scribble (Scrib) is a multidomain polarity protein and member of the leucine-rich repeat and PDZ domain (LAP) protein family. A loss of Scrib expression is associated with disturbed apical-basal polarity and tumor formation. The tumor- ... ...

    Abstract Abstract Scribble (Scrib) is a multidomain polarity protein and member of the leucine-rich repeat and PDZ domain (LAP) protein family. A loss of Scrib expression is associated with disturbed apical-basal polarity and tumor formation. The tumor-suppressive activity of Scrib correlates with its membrane localization. Despite the identification of numerous Scrib-interacting proteins, the mechanisms regulating its membrane recruitment are not fully understood. Here, we identify the cell adhesion receptor TMIGD1 as a membrane anchor of Scrib. TMIGD1 directly interacts with Scrib through a PDZ domain-mediated interaction and recruits Scrib to the lateral membrane domain in epithelial cells. We characterize the association of TMIGD1 with each Scrib PDZ domain and describe the crystal structure of the TMIGD1 C-terminal peptide complexed with PDZ domain 1 of Scrib. Our findings describe a mechanism of Scrib membrane localization and contribute to the understanding of the tumor-suppressive activity of Scrib.
    Keywords Biology (General) ; QH301-705.5
    Subject code 571
    Language English
    Publishing date 2023-07-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Biodegradable and Dual‐Responsive Polypeptide‐Shelled Cyclodextrin‐Containers for Intracellular Delivery of Membrane‐Impermeable Cargo

    Sergej Kudruk / Sharafudheen Pottanam Chali / Anna Livia Linard Matos / Cole Bourque / Clara Dunker / Christos Gatsogiannis / Bart Jan Ravoo / Volker Gerke

    Advanced Science, Vol 8, Iss 18, Pp n/a-n/a (2021)

    2021  

    Abstract: Abstract The transport of membrane impermeable compounds into cells is a prerequisite for the efficient cellular delivery of hydrophilic and amphiphilic compounds and drugs. Transport into the cell's cytosolic compartment should ideally be controllable ... ...

    Abstract Abstract The transport of membrane impermeable compounds into cells is a prerequisite for the efficient cellular delivery of hydrophilic and amphiphilic compounds and drugs. Transport into the cell's cytosolic compartment should ideally be controllable and it should involve biologically compatible and degradable vehicles. Addressing these challenges, nanocontainers based on cyclodextrin amphiphiles that are stabilized by a biodegradable peptide shell are developed and their potential to deliver fluorescently labeled cargo into human cells is analyzed. Host–guest mediated self‐assembly of a thiol‐containing short peptide or a cystamine‐cross‐linked polypeptide shell on cyclodextrin vesicles produce short peptide‐shelled (SPSVss) or polypeptide‐shelled vesicles (PPSVss), respectively, with redox‐responsive and biodegradable features. Whereas SPSVss are permeable and less stable, PPSVss effectively encapsulate cargo and show a strictly regulated release of membrane impermeable cargo triggered by either reducing conditions or peptidase treatment. Live cell experiments reveal that the novel PPSVSS are readily internalized by primary human endothelial cells (human umbilical vein endothelial cells) and cervical cancer cells and that the reductive microenvironment of the cells’ endosomes trigger release of the hydrophilic cargo into the cytosol. Thus, PPSVSS represent a highly efficient, biodegradable, and tunable system for overcoming the plasma membrane as a natural barrier for membrane‐impermeable cargo.
    Keywords biodegradable ; cyclodextrin ; dual‐responsive ; intracellular delivery ; polypeptides ; Science ; Q
    Subject code 571
    Language English
    Publishing date 2021-09-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Membrane Binding Promotes Annexin A2 Oligomerization

    Anna Lívia Linard Matos / Sergej Kudruk / Johanna Moratz / Milena Heflik / David Grill / Bart Jan Ravoo / Volker Gerke

    Cells, Vol 9, Iss 1169, p

    2020  Volume 1169

    Abstract: Annexin A2 (AnxA2) is a cytosolic Ca 2+ regulated membrane binding protein that can induce lipid domain formation and plays a role in exocytosis and endocytosis. To better understand the mode of annexin-membrane interaction, we analyzed membrane-bound ... ...

    Abstract Annexin A2 (AnxA2) is a cytosolic Ca 2+ regulated membrane binding protein that can induce lipid domain formation and plays a role in exocytosis and endocytosis. To better understand the mode of annexin-membrane interaction, we analyzed membrane-bound AnxA2 assemblies by employing a novel 3-armed chemical crosslinker and specific AnxA2 mutant proteins. Our data show that AnxA2 forms crosslinkable oligomers upon binding to membranes containing negatively charged phospholipids. AnxA2 mutants with amino acid substitutions in residues predicted to be involved in lateral protein–protein interaction show compromised oligomer formation, albeit still being capable of binding to negatively charged membranes in the presence of Ca 2+ . These results suggest that lateral protein–protein interactions are involved in the formation of AnxA2 clusters on a biological membrane.
    Keywords annexin A2 ; microdomain ; cross-linker ; quartz crystal microbalance with dissipation monitoring (QCM-D) ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Author Correction

    Anna L. L. Matos / Fabian Keller / Tristan Wegner / Carla Elizabeth Cadena del Castillo / David Grill / Sergej Kudruk / Anne Spang / Frank Glorius / Andreas Heuer / Volker Gerke

    Communications Biology, Vol 4, Iss 1, Pp 1-

    CHIMs are versatile cholesterol analogs mimicking and visualizing cholesterol behavior in lipid bilayers and cells

    2021  Volume 1

    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2021-08-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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