Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells

Riccardo Vago, Catherine J. Marsden, J. Michael Lord, Rodolfo Ippoliti, David J. Flavell, Sopsamorn U. Flavell, Aldo Ceriotti, M. Serena Fabbrini

Research output: Contribution to journalArticle

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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 languageEnglish
Pages (from-to)4983-4995
Number of pages13
JournalFEBS Journal
Volume272
Issue number19
DOIs
Publication statusPublished - Oct 2005

Fingerprint

Ricin
Cytosol
Ribosome Inactivating Proteins
Endoplasmic Reticulum
Plant Proteins
Golgi Apparatus
Endocytosis
Toxicity
Endoplasmic Reticulum-Associated Degradation
Bacterial Toxins
Brefeldin A
Immunotoxins
Vero Cells
Cholera Toxin
Endosomes
Chloroquine
Lysosomes
saporin
Ribosomes
HeLa Cells

Keywords

  • Anticancer therapy
  • Bacterial toxins
  • Intracellular trafficking
  • KDEL retrieval sequence
  • Plant ribosome-inactivating proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Vago, R., Marsden, C. J., Lord, J. M., Ippoliti, R., Flavell, D. J., Flavell, S. U., ... Fabbrini, M. S. (2005). Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells. FEBS Journal, 272(19), 4983-4995. https://doi.org/10.1111/j.1742-4658.2005.04908.x

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 journalArticle

Vago, R, Marsden, CJ, Lord, JM, Ippoliti, R, Flavell, DJ, Flavell, SU, Ceriotti, A & Fabbrini, MS 2005, 'Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells', FEBS Journal, vol. 272, no. 19, pp. 4983-4995. https://doi.org/10.1111/j.1742-4658.2005.04908.x
Vago, Riccardo ; Marsden, Catherine J. ; Lord, J. Michael ; Ippoliti, Rodolfo ; Flavell, David J. ; Flavell, Sopsamorn U. ; Ceriotti, Aldo ; Fabbrini, M. Serena. / Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells. In: FEBS Journal. 2005 ; Vol. 272, No. 19. pp. 4983-4995.
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