Abstract
Several protein toxins, such as the potent plant toxin ricin, enter mammalian cells by endocytosis and undergo retrograde transport via the Golgi complex to reach the endoplasmic reticulum (ER). In this compartment the catalytic moieties exploit the ER-associated degradation (ERAD) pathway to reach their cytosolic targets. Bacterial toxins such as cholera toxin or Pseudomonas exotoxin A carry KDEL or KDEL-like C-terminal tetrapeptides for efficient delivery to the ER. Chimeric toxins containing monomeric plant ribosome-inactivating proteins linked to various targeting moieties are highly cytotoxic, but it remains unclear how these molecules travel within the target cell to reach cytosolic ribosomes. We investigated the intracellular pathways of saporin, a monomeric plant ribosome-inactivating protein that can enter cells by receptor-mediated endocytosis. Saporin toxicity was not affected by treatment with Brefeldin A or chloroquine, indicating that this toxin follows a Golgi-independent pathway to the cytosol and does not require a low pH for membrane translocation. In intoxicated Vero or HeLa cells, ricin but not saporin could be clearly visualized in the Golgi complex using immunofluorescence. The saporin signal was not evident in the Golgi, but was found to partially overlap with that of a late endosome/lysosome marker. Consistently, the toxicities of saporin or saporin-based targeted chimeric polypeptides were not enhanced by the addition of ER retrieval sequences. Thus, the intracellular movement of saporin differs from that followed by ricin and other protein toxins that rely on Golgi-mediated retrograde transport to reach their retrotranslocation site.
| Original language | English |
|---|---|
| Pages (from-to) | 4983-4995 |
| Number of pages | 13 |
| Journal | FEBS Journal |
| Volume | 272 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - Oct 2005 |
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Keywords
- Anticancer therapy
- Bacterial toxins
- Intracellular trafficking
- KDEL retrieval sequence
- Plant ribosome-inactivating proteins
ASJC Scopus subject areas
- Biochemistry
Cite this
Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells. / Vago, Riccardo; Marsden, Catherine J.; Lord, J. Michael; Ippoliti, Rodolfo; Flavell, David J.; Flavell, Sopsamorn U.; Ceriotti, Aldo; Fabbrini, M. Serena.
In: FEBS Journal, Vol. 272, No. 19, 10.2005, p. 4983-4995.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells
AU - Vago, Riccardo
AU - Marsden, Catherine J.
AU - Lord, J. Michael
AU - Ippoliti, Rodolfo
AU - Flavell, David J.
AU - Flavell, Sopsamorn U.
AU - Ceriotti, Aldo
AU - Fabbrini, M. Serena
PY - 2005/10
Y1 - 2005/10
N2 - Several protein toxins, such as the potent plant toxin ricin, enter mammalian cells by endocytosis and undergo retrograde transport via the Golgi complex to reach the endoplasmic reticulum (ER). In this compartment the catalytic moieties exploit the ER-associated degradation (ERAD) pathway to reach their cytosolic targets. Bacterial toxins such as cholera toxin or Pseudomonas exotoxin A carry KDEL or KDEL-like C-terminal tetrapeptides for efficient delivery to the ER. Chimeric toxins containing monomeric plant ribosome-inactivating proteins linked to various targeting moieties are highly cytotoxic, but it remains unclear how these molecules travel within the target cell to reach cytosolic ribosomes. We investigated the intracellular pathways of saporin, a monomeric plant ribosome-inactivating protein that can enter cells by receptor-mediated endocytosis. Saporin toxicity was not affected by treatment with Brefeldin A or chloroquine, indicating that this toxin follows a Golgi-independent pathway to the cytosol and does not require a low pH for membrane translocation. In intoxicated Vero or HeLa cells, ricin but not saporin could be clearly visualized in the Golgi complex using immunofluorescence. The saporin signal was not evident in the Golgi, but was found to partially overlap with that of a late endosome/lysosome marker. Consistently, the toxicities of saporin or saporin-based targeted chimeric polypeptides were not enhanced by the addition of ER retrieval sequences. Thus, the intracellular movement of saporin differs from that followed by ricin and other protein toxins that rely on Golgi-mediated retrograde transport to reach their retrotranslocation site.
AB - Several protein toxins, such as the potent plant toxin ricin, enter mammalian cells by endocytosis and undergo retrograde transport via the Golgi complex to reach the endoplasmic reticulum (ER). In this compartment the catalytic moieties exploit the ER-associated degradation (ERAD) pathway to reach their cytosolic targets. Bacterial toxins such as cholera toxin or Pseudomonas exotoxin A carry KDEL or KDEL-like C-terminal tetrapeptides for efficient delivery to the ER. Chimeric toxins containing monomeric plant ribosome-inactivating proteins linked to various targeting moieties are highly cytotoxic, but it remains unclear how these molecules travel within the target cell to reach cytosolic ribosomes. We investigated the intracellular pathways of saporin, a monomeric plant ribosome-inactivating protein that can enter cells by receptor-mediated endocytosis. Saporin toxicity was not affected by treatment with Brefeldin A or chloroquine, indicating that this toxin follows a Golgi-independent pathway to the cytosol and does not require a low pH for membrane translocation. In intoxicated Vero or HeLa cells, ricin but not saporin could be clearly visualized in the Golgi complex using immunofluorescence. The saporin signal was not evident in the Golgi, but was found to partially overlap with that of a late endosome/lysosome marker. Consistently, the toxicities of saporin or saporin-based targeted chimeric polypeptides were not enhanced by the addition of ER retrieval sequences. Thus, the intracellular movement of saporin differs from that followed by ricin and other protein toxins that rely on Golgi-mediated retrograde transport to reach their retrotranslocation site.
KW - Anticancer therapy
KW - Bacterial toxins
KW - Intracellular trafficking
KW - KDEL retrieval sequence
KW - Plant ribosome-inactivating proteins
UR - http://www.scopus.com/inward/record.url?scp=26244458686&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=26244458686&partnerID=8YFLogxK
U2 - 10.1111/j.1742-4658.2005.04908.x
DO - 10.1111/j.1742-4658.2005.04908.x
M3 - Article
C2 - 16176271
AN - SCOPUS:26244458686
VL - 272
SP - 4983
EP - 4995
JO - FEBS Journal
JF - FEBS Journal
SN - 1742-464X
IS - 19
ER -