gp96 Is a Human Colonocyte Plasma Membrane Binding Protein for Clostridium difficile Toxin A
| Autor: | J. Thomas Lamont, Ho Kim, Xi Na, Charalabos Pothoulakis, Mary Pat Moyer |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Cytoplasm
Cell signaling Colon Bacterial Toxins Immunology Cell Clostridium difficile toxin A Microbiology Cell Line Cell membrane Enterotoxins Cell surface receptor medicine Humans B-Lymphocytes Membrane Glycoproteins biology Clostridioides difficile Binding protein Cell Membrane Epithelial Cells Molecular Pathogenesis Cell biology Membrane glycoproteins Infectious Diseases medicine.anatomical_structure Biochemistry Membrane protein biology.protein Parasitology HT29 Cells |
| Zdroj: | Infection and Immunity. 76:2862-2871 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.00326-08 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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