scholarly journals FERONIA’s sensing of cell wall pectin activates ROP GTPase signaling in Arabidopsis

2018 ◽  
Author(s):  
Wenwei Lin ◽  
Wenxin Tang ◽  
Charles T. Anderson ◽  
Zhenbiao Yang
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Cell Surface Receptor ◽  
Pavement Cell ◽  
Signaling Mechanism ◽  
Rop Gtpase ◽  
Surface Receptor ◽  
A Cell

ABSTRACTPlant cells need to monitor the cell wall dynamic to control the wall homeostasis required for a myriad of processes in plants, but the mechanisms underpinning cell wall sensing and signaling in regulating these processes remain largely elusive. Here, we demonstrate that receptor-like kinase FERONIA senses the cell wall pectin polymer to directly activate the ROP6 GTPase signaling pathway that regulates the formation of the cell shape in the Arabidopsis leaf epidermis. The extracellular malectin domain of FER directly interacts with de-methylesterified pectin in vivo and in vitro. Both loss-of-FER mutations and defects in the pectin biosynthesis and de-methylesterification caused changes in pavement cell shape and ROP6 signaling. FER is required for the activation of ROP6 by de-methylesterified pectin, and physically and genetically interacts with the ROP6 activator, RopGEF14. Thus, our findings elucidate a cell wall sensing and signaling mechanism that connects the cell wall to cellular morphogenesis via the cell surface receptor FER.

scholarly journals gp96 Is a Human Colonocyte Plasma Membrane Binding Protein for Clostridium difficile Toxin A

2008 ◽  
Vol 76 (7) ◽  
pp. 2862-2871 ◽  
Author(s):  
Xi Na ◽  
Ho Kim ◽  
Mary P. Moyer ◽  
Charalabos Pothoulakis ◽  
J. Thomas LaMont
Keyword(s):  
Plasma Membrane ◽  
Clostridium Difficile ◽  
Binding Protein ◽  
Membrane Binding ◽  
Cell Surface Receptor ◽  
Toxin A ◽  
Surface Receptor ◽  
A Cell ◽  
Plasma Membrane Binding

ABSTRACT Clostridium difficile toxin A (TxA), a key mediator of antibiotic-associated colitis, requires binding to a cell surface receptor prior to internalization. Our aim was to identify novel plasma membrane TxA binding proteins on human colonocytes. TxA was coupled with biotin and cross-linked to the surface of HT29 human colonic epithelial cells. The main colonocyte binding protein for TxA was identified as glycoprotein 96 (gp96) by coimmunoprecipitation and mass spectrum analysis. gp96 is a member of the heat shock protein family, which is expressed on human colonocyte apical membranes as well as in the cytoplasm. TxA binding to gp96 was confirmed by fluorescence immunostaining and in vitro coimmunoprecipitation. Following TxA binding, the TxA-gp96 complex was translocated from the cell membrane to the cytoplasm. Pretreatment with gp96 antibody decreased TxA binding to colonocytes and inhibited TxA-induced cell rounding. Small interfering RNA directed against gp96 reduced gp96 expression and cytotoxicity in colonocytes. TxA-induced inflammatory signaling via p38 and apoptosis as measured by activation of BAK (Bcl-2 homologous antagonist/killer) and DNA fragmentation were decreased in gp96-deficient B cells. We conclude that human colonocyte gp96 serves as a plasma membrane binding protein that enhances cellular entry of TxA, participates in cellular signaling events in the inflammatory cascade, and facilitates cytotoxicity.

scholarly journals Antigen 84, an Effector of Pleiomorphism in Mycobacterium smegmatis

2007 ◽  
Vol 189 (21) ◽  
pp. 7896-7910 ◽  
Author(s):  
Liem Nguyen ◽  
Nicole Scherr ◽  
John Gatfield ◽  
Anne Walburger ◽  
Jean Pieters ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Cell Shape ◽  
Gene Disruption ◽  
Gene Encoding ◽  
Peptidoglycan Biosynthesis ◽  
Asymmetrically Distributed ◽  
Cell Wall Expansion

ABSTRACT While in most rod-shaped bacteria, morphology is based on MreB-like proteins that form an actin-like cytoskeletal scaffold for cell wall biosynthesis, the factors that determine the more flexible rod-like shape in actinobacteria such as Mycobacterium species are unknown. Here we show that a Mycobacterium smegmatis protein homologous to eubacterial DivIVA-like proteins, including M. tuberculosis antigen 84 (Ag84), localized symmetrically to centers of peptidoglycan biosynthesis at the poles and septa. Controlled gene disruption experiments indicated that the gene encoding Ag84, wag31, was essential; when overexpressed, cells became longer and wider, with Ag84 asymmetrically distributed at one pole. Many became grossly enlarged, bowling-pin-shaped cells having up to 80-fold-increased volume. In these cells, Ag84 accumulated predominantly at a bulbous pole that was apparently generated by uncontrolled cell wall expansion. In some cells, Ag84 was associated with exceptional sites of cell wall expansion (buds) that evolved into branches. M. bovis BCG Ag84 was able to form oligomers in vitro, perhaps reflecting its superstructure in vivo. These data suggested a role for Ag84 in cell division and modulating cell shape in pleiomorphic actinobacteria.

scholarly journals Minireview: A Novel Pathway of Prostacyclin Signaling—Hanging Out with Nuclear Receptors

Endocrinology ◽  
2002 ◽  
Vol 143 (9) ◽  
pp. 3207-3210 ◽  
Author(s):  
Hyunjung Lim ◽  
Sudhansu K. Dey
Keyword(s):  
Cell Surface ◽  
Nuclear Receptors ◽  
Wide Spectrum ◽  
Binding Pocket ◽  
Cell Surface Receptor ◽  
Lipoxygenase Pathway ◽  
Signaling Mechanism ◽  
Recent Developments ◽  
Surface Receptor

Abstract Prostacylin (PGI2), one of the major prostaglandins, is derived from arachidonic acid by the action of the cyclooxygenase (COX) system coupled to PGI2 synthase (PGIS). The presence of the COX-2/PGIS at the nuclear and endoplasmic reticular membrane suggests differential signaling pathways of PGI2 actions involving both cell surface and nuclear receptors. Although the signaling of PGI2 via its cell surface receptor, prostacyclin receptor (IP), is well documented in vascular biology, its action via nuclear receptors in other physiological responses is gradually being more appreciated. Peroxisomal proliferator-activated receptors (PPARs), PPARα, PPARγ, and PPARδ, though initially cloned as a family of orphan receptors, are now known for their ligand promiscuity. The ligands range from free fatty acids and their derivatives produced by the cyclooxygenase or lipoxygenase pathway to certain hypolipidemic drugs. The predisposition of PPARs to use a wide spectrum of ligands is well explained by their unusually large ligand-binding pocket. The promiscuous ligand usage by PPARs is also reflected by their involvement in various pathophysiological events. Several recent independent reports show that endogenously produced PGI2 indeed activates PPARδ in vivo, indicating that a novel signaling mechanism for this abundant eicosanoid is operative in certain systems. This review attempts to cover recent developments in nuclear actions of PGI2 in diverse biological functions.

scholarly journals Structural basis of peptidoglycan endopeptidase regulation

2020 ◽  
Vol 117 (21) ◽  
pp. 11692-11702 ◽  
Author(s):  
Jung-Ho Shin ◽  
Alan G. Sulpizio ◽  
Aaron Kelley ◽  
Laura Alvarez ◽  
Shannon G. Murphy ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Basis ◽  
Bacterial Cells ◽  
Cell Wall Degradation ◽  
Open Conformation ◽  
Poor Understanding ◽  
A Cell ◽  
Inhibitory Domain

Most bacteria surround themselves with a cell wall, a strong meshwork consisting primarily of the polymerized aminosugar peptidoglycan (PG). PG is essential for structural maintenance of bacterial cells, and thus for viability. PG is also constantly synthesized and turned over; the latter process is mediated by PG cleavage enzymes, for example, the endopeptidases (EPs). EPs themselves are essential for growth but also promote lethal cell wall degradation after exposure to antibiotics that inhibit PG synthases (e.g., β-lactams). Thus, EPs are attractive targets for novel antibiotics and their adjuvants. However, we have a poor understanding of how these enzymes are regulated in vivo, depriving us of novel pathways for the development of such antibiotics. Here, we have solved crystal structures of the LysM/M23 family peptidase ShyA, the primary EP of the cholera pathogenVibrio cholerae. Our data suggest that ShyA assumes two drastically different conformations: a more open form that allows for substrate binding and a closed form, which we predicted to be catalytically inactive. Mutations expected to promote the open conformation caused enhanced activity in vitro and in vivo, and these results were recapitulated in EPs from the divergent pathogensNeisseria gonorrheaeandEscherichia coli. Our results suggest that LysM/M23 EPs are regulated via release of the inhibitory Domain 1 from the M23 active site, likely through conformational rearrangement in vivo.

Participation of urokinase-type plasminogen activator receptor in the clearance of fibrin from the lung

1999 ◽  
Vol 277 (3) ◽  
pp. L573-L579 ◽  
Author(s):  
Noboru Hattori ◽  
Thomas H. Sisson ◽  
Yin Xu ◽  
Tushar J. Desai ◽  
Richard H. Simon
Keyword(s):  
Plasminogen Activator ◽  
Cell Surface Receptor ◽  
Biologically Relevant ◽  
Knowing That ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Surface Receptor ◽  
Species Specific

In vitro studies have demonstrated that the binding of urokinase-type plasminogen activator (uPA) to its cell surface receptor (uPAR) greatly accelerates plasminogen activation. However, the role of uPAR in clearing abnormal fibrin deposits from the lung is uncertain. Knowing that uPA binding to uPAR is species specific, we used adenoviral vectors to transfer human or murine uPA genes into human or mouse epithelial cells in vitro and to mouse lungs in vivo. By measuring degradation of fluorescein-labeled fibrin, we found that uPA lysed fibrin matrices more efficiently when expressed in cells of the same species. A monoclonal antibody that blocks the binding of human uPA to human uPAR suppressed fibrin degradation by human cells expressing human uPA but not murine uPA. Importantly, 3 days after intratracheal delivery of the vectors, mice receiving murine uPA transgenes degraded fibrin matrices formed within their air spaces more efficiently than animals transduced with human uPA genes. These results show that uPA bound to uPAR increases the efficiency of fibrinolysis on epithelial cell surfaces in a biologically relevant fashion.

Participation of multiple factors, including proliferin, in the inhibition of myogenic differentiation

1989 ◽  
Vol 9 (2) ◽  
pp. 430-441
Author(s):  
E L Wilder ◽  
D I Linzer
Keyword(s):  
Cell Lines ◽  
Myogenic Differentiation ◽  
Gene Promoter ◽  
Myogenic Cell ◽  
Cell Surface Receptor ◽  
Specific Gene ◽  
Amino Acid Residues ◽  
Surface Receptor ◽  
A Cell

Proliferin (PLF) is a secreted glycoprotein in the prolactin-growth hormone family in mice. PLF expression was detected in C3H 10T1/2 fibroblasts, but not in two 10T1/2-derived myogenic cell lines, and was restored in two nondifferentiating variants of one of these myogenic cell lines. Transient expression of one form of PLF (PLF1) inhibited expression from a muscle-specific gene promoter; a second form of PLF, which differed at three amino acid residues, displayed no activity in this transient assay. Introduction of a PLF1 expression construct into both muscle- and 10T1/2-derived myoblasts resulted in cell lines that were no longer myogenic or that differentiated only partially. Analysis of these cell lines revealed that differentiation could be obstructed at several steps and by one or more factors in addition to PLF. Although expected to function in vivo as an extracellular hormone, PLF did not appear to be acting through a cell surface receptor to inhibit differentiation in these cultured myoblasts.

scholarly journals In vivo paracrine interaction between urokinase and its receptor: effect on tumor cell invasion.

1991 ◽  
Vol 115 (4) ◽  
pp. 1107-1112 ◽  
Author(s):  
L Ossowski ◽  
G Clunie ◽  
M T Masucci ◽  
F Blasi
Keyword(s):  
Chorioallantoic Membrane ◽  
Fold Increase ◽  
Cell Types ◽  
Cell Surface Receptor ◽  
In Vivo Model ◽  
Specific Cell ◽  
Upa Receptor ◽  
Surface Receptor

Numerous studies have linked the production of increased levels of urokinase type plasminogen activator (uPA) with the malignant phenotype. It has also been shown that a specific cell surface receptor can bind uPA through a domain distinct and distant from the proteolytic domain. In an in vivo model of invasion, consisting of experimentally modified chorioallantoic membrane (CAM) of a chick embryo, only cells that concurrently expressed both uPA and a receptor for uPA, and in which the receptor was saturated with uPA, were efficient in invasion. To test whether uPA produced by one cell can, in a paracrine fashion, affect the invasive capacity of a receptor-expressing cell, we transfected LB6 mouse cells with human uPA (LB6[uPA]), or human uPA-receptor cDNA (LB6[uPAR]). LB6(uPA) cells released into the medium 1-2 Ploug units of human uPA per 10(6) cells in 24 h. The LB6(uPAR) cells expressed on their surface approximately 12,000 high affinity (Kd 1.7 x 10(-10) M uPA binding sites per cell. Unlabeled LB6(uPA) and 125-IUdR-labeled LB6(uPAR) cells were coinoculated onto experimentally wounded and resealed CAMs and their invasion was compared to that of homologous mixtures of labeled and unlabeled LB6(uPAR) or LB6(uPA) cells. Concurrent presence of both cell types in the CAMs resulted in a 1.8-fold increase of invasion of the uPA-receptor expressing cells. A four-fold stimulation of invasion was observed when cells were cocultured in vitro, prior to in vivo inoculation. Enhancement of invasion was prevented in both sets of experiments by treatment with specific antihuman uPA antibodies, indicating that uPA was the main mediator of the invasion-enhancing, paracrine effect on the receptor-expressing cells.

S100A10 regulates plasminogen-dependent macrophage invasion

Blood ◽  
2010 ◽  
Vol 116 (7) ◽  
pp. 1136-1146 ◽  
Author(s):  
Paul A. O'Connell ◽  
Alexi P. Surette ◽  
Robert S. Liwski ◽  
Per Svenningsson ◽  
David M. Waisman
Keyword(s):  
Cell Surface Receptor ◽  
Macrophage Migration ◽  
Plasminogen Activation System ◽  
Inflammatory Stimuli ◽  
Integral Role ◽  
Surface Receptor ◽  
First Time

Abstract The plasminogen activation system plays an integral role in the migration of macrophages in response to an inflammatory stimulus, and the binding of plasminogen to its cell-surface receptor initiates this process. Although previous studies from our laboratory have shown the importance of the plasminogen receptor S100A10 in cancer cell plasmin production, the potential role of this protein in macrophage migration has not been investigated. Using thioglycollate to induce a peritoneal inflammatory response, we demonstrate, for the first time, that compared with wild-type (WT) mice, macrophage migration across the peritoneal membrane into the peritoneal cavity in S100A10-deficient (S100A10−/−) mice was decreased by up to 53% at 24, 48, and 72 hours. Furthermore, the number of S100A10-deficient macrophages that infiltrated Matrigel plugs was reduced by 8-fold compared with their WT counterpart in vivo. Compared with WT macrophages, macrophages from S100A10−/− mice demonstrated a 50% reduction in plasmin-dependent invasion across a Matrigel barrier and a 45% reduction in plasmin generation in vitro. This loss in plasmin-dependent invasion was in part the result of a decreased generation of plasmin and a decreased activation of pro-MMP-9 by S100A10-deficient macrophages. This study establishes a direct involvement of S100A10 in macrophage recruitment in response to inflammatory stimuli.

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