Evidence for in vivo inhibition of a cell surface protease associated with tumour cells

Electric field pulses are a new approach for drug and gene delivery for cancer therapy. They induce a localized structural alteration of cell membranes. The associated physical mechanisms are well explained and can be safely controlled. A position dependent modulation of the membrane potential difference is induced when an electric field is applied to a cell. Electric field pulses with an overcritical intensity evoke a local membrane alteration. A free exchange of hydrophilic low molecular weight molecules takes place across the membrane. A leakage of cytosolic metabolites and a loading of polar drugs into the cytoplasm are obtained. The fraction of the cell surface which is competent for exchange is a function of the field intensity. The level of local exchange is strongly controlled by the pulse duration and the number of successive pulses. The permeabilised state is long lived. Its lifetime is under the control of the cumulated pulse duration. Cell viability can be preserved. Gene transfer is obtained but its mechanism is not a free diffusion. Plasmids are electrophoretically accumulated against the permeabilised cell surface and form aggregates due to the field effect. After the pulses, several steps follow: translocation to the cytoplasm, traffic to the nucleus and expression. Molecular structural and metabolic changes in cells remain mostly poorly understood. Nevertheless, while most studies were established on cells in culture ( in vitro), recent experiments show that similar effects are obtained on tissue ( in vivo). Transfer remains controlled by the physical parameters of the electrical treatment.

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Involvement of Domain 3 in Oligomerization by the Protective Antigen Moiety of Anthrax Toxin

Journal of Bacteriology ◽

10.1128/jb.183.6.2111-2116.2001 ◽

2001 ◽

Vol 183 (6) ◽

pp. 2111-2116 ◽

Cited By ~ 64

Author(s):

Jeremy Mogridge ◽

Michael Mourez ◽

R. John Collier

Keyword(s):

Cell Surface ◽

Mammalian Cells ◽

Protective Antigen ◽

Anthrax Toxin ◽

Membrane Insertion ◽

A Cell ◽

Domain 3 ◽

Active Fragment ◽

Cell Surface Protease ◽

Pa Domain

ABSTRACT Protective antigen (PA), a component of anthrax toxin, binds receptors on mammalian cells and is activated by a cell surface protease. The resulting active fragment, PA63, forms ring-shaped heptamers, binds the enzymic moieties of the toxin, and translocates them to the cytosol. Of the four crystallographic domains of PA, domain 1 has been implicated in binding the enzymic moieties; domain 2 is involved in membrane insertion and oligomerization; and domain 4 binds receptor. To determine the function of domain 3, we developed a screen that allowed us to isolate random mutations that cause defects in the activity of PA. We identified several mutations in domain 3 that affect monomer-monomer interactions in the PA63 heptamer, indicating that this may be the primary function of this domain.

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Cytotoxicity of a cell-reactive immunotoxin containing ricin A chain is potentiated by an anti-immunotoxin containing ricin B chain.

Journal of Experimental Medicine ◽

10.1084/jem.160.1.341 ◽

1984 ◽

Vol 160 (1) ◽

pp. 341-346 ◽

Cited By ~ 46

Author(s):

E S Vitetta ◽

R J Fulton ◽

J W Uhr

Keyword(s):

Cell Surface ◽

Cell Line ◽

Ricin A Chain ◽

Daudi Cell ◽

A Cell ◽

A Chain ◽

Ricin A

In vitro killing of the human Daudi cell line by either univalent [F(ab')] or divalent (IgG) forms of rabbit anti-human Ig (RAHIg) coupled to ricin A chain can be specifically potentiated by a "piggyback" treatment with ricin B chain coupled to goat anti-rabbit Ig (GARIg). When cells are treated with univalent immunotoxin (IT) [F(ab') RAHIg-A] and then cultured, IT can be detected on the cell surface for at least 5 h, since GARIg-B can still enhance killing at this time. These results provide a strategy for in vivo use of A chain- and B chain-containing IT.

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Cholangiocyte expression of α2β1-integrin confers susceptibility to rotavirus-induced experimental biliary atresia

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00442.2007 ◽

2008 ◽

Vol 295 (1) ◽

pp. G16-G26 ◽

Cited By ~ 30

Author(s):

Mubeen Jafri ◽

Bryan Donnelly ◽

Steven Allen ◽

Alex Bondoc ◽

Monica McNeal ◽

...

Keyword(s):

Monoclonal Antibody ◽

Cell Surface ◽

Biliary Atresia ◽

Cell Lines ◽

Surface Expression ◽

Cell Surface Expression ◽

Newborn Mice ◽

A Cell

Inoculation of BALB/c mice with rhesus rotavirus (RRV) in the newborn period results in biliary epithelial cell (cholangiocyte) infection and the murine model of biliary atresia. Rotavirus infection of a cell requires attachment, which is governed in part by cell-surface expression of integrins such as α2β1. We hypothesized that cholangiocytes were susceptible to RRV infection because they express α2β1. RRV attachment and replication was measured in cell lines derived from cholangiocytes and hepatocytes. Flow cytometry was performed on these cell lines to determine whether α2β1 was present. Cholangiocytes were blocked with natural ligands, a monoclonal antibody, or small interfering RNA against the α2-subunit and were infected with RRV. The extrahepatic biliary tract of newborn mice was screened for the expression of the α2β1-integrin. Newborn mice were pretreated with a monoclonal antibody against the α2-subunit and were inoculated with RRV. RRV attached and replicated significantly better in cholangiocytes than in hepatocytes. Cholangiocytes, but not hepatocytes, expressed α2β1 in vitro and in vivo. Blocking assays led to a significant reduction in attachment and yield of virus in RRV-infected cholangiocytes. Pretreatment of newborn pups with an anti-α2 monoclonal antibody reduced the ability of RRV to cause biliary atresia in mice. Cell-surface expression of the α2β1-integrin plays a role in the mechanism that confers cholangiocyte susceptibility to RRV infection.

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Compartment-Restricted Biotinylation Reveals Novel Features of Prion Protein Metabolism in Vivo

Molecular Biology of the Cell ◽

10.1091/mbc.e10-09-0742 ◽

2010 ◽

Vol 21 (24) ◽

pp. 4325-4337 ◽

Cited By ~ 33

Author(s):

Amy B. Emerman ◽

Zai-Rong Zhang ◽

Oishee Chakrabarti ◽

Ramanujan S. Hegde

Keyword(s):

Cell Surface ◽

Prion Protein ◽

Protein Metabolism ◽

Selective Detection ◽

Wild Type ◽

Selective Labeling ◽

A Cell ◽

Cellular Compartments ◽

Made In

Proteins are often made in more than one form, with alternate versions sometimes residing in different cellular compartments than the primary species. The mammalian prion protein (PrP), a cell surface GPI-anchored protein, is a particularly noteworthy example for which minor cytosolic and transmembrane forms have been implicated in disease pathogenesis. To study these minor species, we used a selective labeling strategy in which spatially restricted expression of a biotinylating enzyme was combined with asymmetric engineering of the cognate acceptor sequence into PrP. Using this method, we could show that even wild-type PrP generates small amounts of the CtmPrP transmembrane form. Selective detection of CtmPrP allowed us to reveal its N-terminal processing, long half-life, residence in both intracellular and cell surface locations, and eventual degradation in the lysosome. Surprisingly, some human disease-causing mutants in PrP selectively stabilized CtmPrP, revealing a previously unanticipated mechanism of CtmPrP up-regulation that may contribute to disease. Thus, spatiotemporal tagging has uncovered novel aspects of normal and mutant PrP metabolism and should be readily applicable to the analysis of minor topologic isoforms of other proteins.

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