Shiga toxin binding to globotriaosyl ceramide induces intracellular signals that mediate cytoskeleton remodeling in human renal carcinoma-derived cells

Takenouchi, Hisami; Kiyokawa, Nobutaka; Taguchi, Tomoko; Matsui, Jun; Katagiri, Yohko U.; Okita, Hajime; Okuda, Kenji; Fujimoto, Junichiro

doi:10.1242/jcs.01246

Cited by 80 publications

(76 citation statements)

References 62 publications

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“…Several studies have shown that Stx, upon binding or entry into cells, is able to trigger signaling cascades (Katagiri et al, 1999;Ikeda et al, 2000;Mori et al, 2000;Cameron et al, 2003;Takenouchi et al, 2004). However, the main focus has been on Stx-induced apoptosis and signaling related to this late event.…”

Section: Introductionmentioning

confidence: 99%

The Mitogen-activated Protein Kinase p38 Links Shiga Toxin-dependent Signaling and Trafficking

Wälchli¹,

Skånland

Gregers

et al. 2008

MBoC

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Shiga toxin (Stx) binds to the cell, and it is transported via endosomes and the Golgi apparatus to the endoplasmic reticulum and cytosol, where it exerts its toxic effect. We have recently shown that Stx activates the tyrosine kinase Syk, which in turn induces clathrin phosphorylation and up-regulates Stx uptake. Here, we show that toxin-induced signaling can also regulate another step in intracellular Stx transport. We demonstrate that transport of Stx to the Golgi apparatus is dependent on the mitogen-activated protein kinase p38. Treatment of cells with chemical inhibitors or small interfering RNA targeting p38 inhibited Stx transport to the Golgi and reduced Stx toxicity. This p38 dependence is specific to Stx, because transport of the related toxin ricin was not affected by p38 inhibition. Stx rapidly activated p38, and recruited it to early endosomes in a Ca 2؉ -dependent manner. Furthermore, agonist-induced oscillations in cytosolic Ca 2؉ levels were inhibited upon Stx stimulation, possibly reflecting Stx-dependent local alterations in cytosolic Ca 2؉ levels. Intracellular transport of Stx is Ca 2؉ dependent, and we provide evidence that Stx activates a signaling cascade involving cross talk between Ca 2؉ and p38, to regulate its trafficking to the Golgi apparatus.

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Section: Introductionmentioning

confidence: 99%

The Mitogen-activated Protein Kinase p38 Links Shiga Toxin-dependent Signaling and Trafficking

Wälchli¹,

Skånland

Gregers

et al. 2008

MBoC

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“…In addition to activating endocytosis, Shiga toxin may influence signaling important for later trafficking events. After Shiga toxin binds to the cell surface, there is an increase in MT assembly and the number of microfilaments (Takenouchi et al, 2004). STxB stimulates dynein-based motility that may facilitate its own transport to the juxtanuclear Golgi apparatus (Hehnly et al, 2006).…”

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confidence: 99%

Retrograde Shiga Toxin Trafficking Is Regulated by ARHGAP21 and Cdc42

Hehnly

Longhini

Chen

et al. 2009

MBoC

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Shiga-toxin-producing Escherichia coli remain a food-borne health threat. Shiga toxin is endocytosed by intestinal epithelial cells and transported retrogradely through the secretory pathway. It is ultimately translocated to the cytosol where it inhibits protein translation. We found that Shiga toxin transport through the secretory pathway was dependent on the cytoskeleton. Recent studies reveal that Shiga toxin activates signaling pathways that affect microtubule reassembly and dynein-dependent motility. We propose that Shiga toxin alters cytoskeletal dynamics in a way that facilitates its transport through the secretory pathway. We have now found that Rho GTPases regulate the endocytosis and retrograde motility of Shiga toxin. The expression of RhoA mutants inhibited endocytosis of Shiga toxin. Constitutively active Cdc42 or knockdown of the Cdc42-specific GAP, ARHGAP21, inhibited the transport of Shiga toxin to the juxtanuclear Golgi apparatus. The ability of Shiga toxin to stimulate microtubule-based transferrin transport also required Cdc42 and ARHGAP21 function. Shiga toxin addition greatly decreases the levels of active Cdc42-GTP in an ARHGAP21-dependent manner. We conclude that ARHGAP21 and Cdc42-based signaling regulates the dynein-dependent retrograde transport of Shiga toxin to the Golgi apparatus. INTRODUCTIONEnteritis caused by Shigella dysenteria and pathogenic strains of Escherichia coli is a global health threat. These bacteria secrete Shiga toxin that enters intestinal epithelial cells and kills them by blocking translation. In some cases, the toxin escapes the gut and targets the kidney and vascular endothelium resulting in hemolytic-uremic syndrome (Sandvig and van Deurs, 2000; O'Loughlin and RobinsBrowne, 2001;Proulx et al., 2001;Desch and Motto, 2007). Treatment options for Escherichia coli infection and hemolyticuremic syndrome are limited in part because of an incomplete understanding of the molecular mechanisms underlying Shiga toxin's trafficking within cells.Shiga toxin reaches the cytosol by using retrograde transport through the secretory pathway (Sandvig and van Deurs, 2002;Johannes and Popoff, 2008). Shiga toxin is a heteromultimeric protein containing one A subunit and five B subunits. The A subunit is an N-glycosidase that inhibits protein translation, whereas the Shiga toxin B subunits (STxBs) mediate intracellular targeting. STxB binds to the cell surface via a glycolipid receptor, globotriaosyl ceramide (Gb3). Entry is mediated by clathrin-dependent or -independent endocytosis (Lingwood, 1993;Sandvig and van Deurs, 2000). It is transported from early endosomes to the Golgi complex before undergoing COPI-independent retrograde transport to the endoplasmic reticulum (Mallard et al., 1998;Girod et al., 1999;Falguieres et al., 2001;Luna et al., 2002;Lauvrak et al., 2004;McKenzie et al., 2009). The A subunit exits the endoplasmic reticulum into the cytosol where it cleaves the rRNA (Obrig et al., 1985).Shiga toxin usurps several components of the constitutive trafficking machinery t...

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“…These kinases do not seem to regulate the uptake of the toxin, but rather to be involved in the endosome-to-Golgi transport step (see below). Moreover, Stx has been shown to stimulate microtubule assembly in ACHN cells [38] and in Vero cells [39], and both microtubules and dynein were found to be required for transport of Stx to the Golgi [39]. Notably, it was shown that the Stx-induced activation of microtubuli assembly was not mediated via Syk, suggesting that multiple signaling pathways are induced by Stx.…”

Section: B B Bmentioning

confidence: 99%

The Intracellular Journey of Shiga Toxins

Torgersen¹

2013

TOTNJ

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Abstract:The Shiga toxin family consists of Shiga toxin (Stx) that is produced as a virulence factor by Shigella dysenteriae, and the Shiga-like toxins produced by certain strains of enterohemorrhagic E. coli as well as by some other types of bacteria. Infection with bacteria producing these toxins is a threat to human health even in industrialized countries, as the initial diarrhea caused by the infection might be followed by a complication named hemolytic uremic syndrome. The Shiga toxins consist of a binding moiety that in most cases binds to the glycosphingolipid Gb3 on the surface of susceptible cells, and an A-moiety responsible for the toxic effect in the cytosol. In order to reach its cytosolic target, the toxin must be internalized and then transported via the retrograde pathway to the Golgi complex and further to the endoplasmic reticulum. From the endoplasmic reticulum the enzymatically active part of the A-moiety is translocated to the cytosol, and cellular protein synthesis is inhibited. Although the Shiga toxins are involved in disease, they may also be exploited for medical diagnosis and treatment. Interestingly, the toxin receptor, Gb3, has a limited expression in normal tissues, but is overexpressed in several types of cancer. Thus, the use of Shiga toxin, or the binding part of the toxin, has great potential in cancer diagnostics and treatment. Furthermore, studies of the various uptake mechanisms and intracellular transport pathways exploited by the toxins, provide important insight in basic cell biology processes.

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Shiga toxin binding to globotriaosyl ceramide induces intracellular signals that mediate cytoskeleton remodeling in human renal carcinoma-derived cells

Cited by 80 publications

References 62 publications

The Mitogen-activated Protein Kinase p38 Links Shiga Toxin-dependent Signaling and Trafficking

The Mitogen-activated Protein Kinase p38 Links Shiga Toxin-dependent Signaling and Trafficking

Retrograde Shiga Toxin Trafficking Is Regulated by ARHGAP21 and Cdc42

The Intracellular Journey of Shiga Toxins

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