title: The host adherens junction molecule nectin-1 is degraded by chlamydial protease-like activity factor (CPAF) in Chlamydia trachomatis-infected genital epithelial cells.
abstract: Nectin-1 is an adhesion protein implicated in the organization of adherens junctions and tight junctions in epithelial cells. Previous studies in our laboratory demonstrated that nectin-1 accumulation was significantly decreased in Chlamydia trachomatis-infected HeLa cells. In the present study, Western blot analyses indicated that nectin-1 down-regulation was C. trachomatis concentration-dependent. The half-life of nectin-1 was also greatly diminished in C. trachomatis-infected cells compared to that observed in mock-infected cells, indicating that nectin-1 was likely down-regulated post-translationally. The chlamydia-secreted protease CPAF is known to degrade several important host proteins; CPAF expression within infected cells correlated with the time-dependent cleavage of nectin-1. Notably, CPAF proteolytic activity is inhibited by lactacystin but not by the proteosome inhibitor MG132. In vivo inhibition experiments demonstrated that nectin-1 down-regulation was blocked by lactacystin exposure. In contrast, MG132 had no effect. Finally, cell-free cleavage assays demonstrated that functional recombinant GST-CPAF(wt) protein degrades nectin-1. This degradation was blocked by lactacystin, as previously observed in vivo. Collectively, these results indicate that nectin-1 is degraded by CPAF in C. trachomatis-infected cells, a novel strategy that chlamydiae may use to aid their dissemination.
authors.affiliation: Department of Microbiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
authors.forename: Jingru
authors.initials: J
authors.lastname: Sun
authors.forename: Robert V
authors.initials: RV
authors.lastname: Schoborg
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D001426:Bacterial Proteins / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002692:Chlamydia trachomatis / Q000201:enzymology / Q000472:pathogenicity*; D015536:Down-Regulation; D010450:Endopeptidases / Q000378:metabolism*; D004847:Epithelial Cells / Q000382:microbiology* / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D000075983:Nectins
chemical_list: D001426:Bacterial Proteins; D015815:Cell Adhesion Molecules; C000619010:NECTIN1 protein, human; D000075983:Nectins; D010450:Endopeptidases