Activation of G signaling by Pasteurella multocida toxin inhibits the osteoblastogenic-like actions of Activin A in C2C12 myoblasts, a cell model of fibrodysplasia ossificans progressiva.

The human disease fibrodysplasia ossificans progressiva (FOP) is a rare and highly disabling disorder of extensive heterotopic bone growth that is caused by a point mutation (R206H) in the activation domain of Alk2, a BMP (bone morphogenic protein) type 1 receptor. The mutation leads to extensive BMP-signaling induced by Activin A, which is normally an antagonist for wildtype receptors, resulting in excessive and uncontrolled bone formation. Here, we studied the effects of Pasteurella multocida toxin (PMT), which activates osteoclasts and inhibits osteoblast activity, in C2C12 myoblasts expressing the mutant Alk2(R206H) receptor as model of FOP.

Involvement of Osteocytes in the Action of Toxin.

toxin (PMT) causes progressive atrophic rhinitis with severe turbinate bone degradation in pigs. It has been reported that the toxin deamidates and activates heterotrimeric G proteins, resulting in increased differentiation of osteoclasts and blockade of osteoblast differentiation. So far, the action of PMT on osteocytes, which is the most abundant cell type in bone tissue, is not known.

Salmonella Typhimurium effector SseI inhibits chemotaxis and increases host cell survival by deamidation of heterotrimeric Gi proteins.

Salmonella enterica serotype Typhimurium (S. Typhimurium) is one of the most frequent causes of food-borne illness in humans and usually associated with acute self-limiting gastroenteritis. However, in immunocompromised patients, the pathogen can disseminate and lead to severe systemic diseases.

The two-pore channel TPC1 is required for efficient protein processing through early and recycling endosomes.

Two-pore channels (TPCs) are localized in endo-lysosomal compartments and assumed to play an important role for vesicular fusion and endosomal trafficking. Recently, it has been shown that both TPC1 and 2 were required for host cell entry and pathogenicity of Ebola viruses. Here, we investigate the cellular function of TPC1 using protein toxins as model substrates for distinct endosomal processing routes.

Auranofin Inhibits the Enzyme Activity of Pasteurella multocida Toxin PMT in Human Cells and Protects Cells from Intoxication.

The AB-type protein toxin from (PMT) contains a functionally important disulfide bond within its catalytic domain, which must be cleaved in the host cell cytosol to render the catalytic domain of PMT into its active conformation. Here, we found that the reductive potential of the cytosol of target cells, and more specifically, the activity of the thioredoxin reductase (TrxR) is crucial for this process. This was demonstrated by the strong inhibitory effect of the pharmacological TrxR inhibitor auranofin, which inhibited the intoxication of target cells with PMT, as determined by analyzing the PMT-catalyzed deamidation of GTP-binding proteins (G-proteins) in the cytosol of cells.

A systemic Pasteurella multocida toxin aggravates cardiac hypertrophy and fibrosis in mice.

Pasteurella multocida toxin (PMT) persistently activates heterotrimeric G proteins of the Gαq/11 , Gα12/13 and Gαi family without interaction with G protein-coupled receptors (GPCRs). We show that PMT acts on heart tissue in vivo and on cardiomyocytes and cardiac fibroblasts in vitro by deamidation of heterotrimeric G proteins. Increased normalized ventricle weights and fibrosis were detected after intraperitoneal administration of PMT in combination with the GPCR agonist phenylephrine.

Granzyme A produces bioactive IL-1β through a nonapoptotic inflammasome-independent pathway.

Bacterial components are recognized by the immune system through activation of the inflammasome, eventually causing processing of the proinflammatory cytokine interleukin-1? (IL-1?), a pleiotropic cytokine and one of the most important mediators of inflammation, through the protease caspase-1. Synthesis of the precursor protein and processing into its bioactive form are tightly regulated, given that disturbed control of IL-1? release can cause severe autoinflammatory diseases or contribute to cancer development. We show that the bacterial Pasteurella multocida toxin (PMT) triggers Il1b gene transcription in macrophages independently of Toll-like receptor signaling through RhoA/Rho-kinase-mediated NF-?? activation.

Noncanonical G-protein-dependent modulation of osteoclast differentiation and bone resorption mediated by Pasteurella multocida toxin.

Unlabelled: Pasteurella multocida toxin (PMT) induces atrophic rhinitis in animals, which is characterized by a degradation of nasal turbinate bones, indicating an effect of the toxin on bone cells such as osteoblasts and osteoclasts. The underlying molecular mechanism of PMT was defined as a persistent activation of heterotrimeric G proteins by deamidation of a specific glutamine residue. Here, we show that PMT acts directly on osteoclast precursor cells such as bone marrow-derived CD14(+) monocytes and RAW246.

A bacterial toxin catalyzing tyrosine glycosylation of Rho and deamidation of Gq and Gi proteins.

Entomopathogenic Photorhabdus asymbiotica is an emerging pathogen in humans. Here, we identified a P. asymbiotica protein toxin (PaTox), which contains a glycosyltransferase and a deamidase domain.

Pasteurella multocida toxin prevents osteoblast differentiation by transactivation of the MAP-kinase cascade via the Gα(q/11)--p63RhoGEF--RhoA axis.

The 146-kDa Pasteurella multocida toxin (PMT) is the main virulence factor to induce P. multocida-associated progressive atrophic rhinitis in various animals. PMT leads to a destruction of nasal turbinate bones implicating an effect of the toxin on osteoblasts and/or osteoclasts.

Pasteurella multocida toxin as a transporter of non-cell-permeating proteins.

The protein toxin Pasteurella multocida toxin (PMT) is the causative agent of atrophic rhinitis in pigs, leading to atrophy of the nasal turbinate bones by affecting osteoblasts and osteoclasts. The mechanism of PMT-induced intoxication is a deamidation of α-subunits of heterotrimeric G proteins, including Gαq, Gα13, and Gαi, thereby causing persistent activation of the G proteins. Here we utilized PMT as a transporter of the non-cell-permeating A domain of diphtheria toxin (DTa).

Substrate specificity of Pasteurella multocida toxin for α subunits of heterotrimeric G proteins.

Pasteurella multocida is the causative agent of a number of epizootic and zoonotic diseases. Its major virulence factor associated with atrophic rhinitis in animals and dermonecrosis in bite wounds is P. multocida toxin (PMT).

Molecular biology of Pasteurella multocida toxin.

Pasteurella multocida toxin (PMT) is the causative agent of progressive atrophic rhinitis in swine. The 146 kDa single-chain toxin harbours discrete domains important for receptor binding, internalisation and biological activity. The molecular basis of the toxin's activity is the deamidation of a specific glutamine residue in the α-subunit of heterotrimeric G proteins.

Cell-free synthesis and characterization of a novel cytotoxic pierisin-like protein from the cabbage butterfly Pieris rapae.

Pierisin-like proteins comprise a growing family of ADP-ribosyltransferases expressed in various species of white butterflies. The prototype pierisin-1 from the cabbage butterfly, Pieris rapae, was identified as a potent apoptosis-inducing agent, acting on various types of carcinoma cell lines by mono-ADP-ribosylation of DNA. The characterization of pierisin-like proteins is hampered by its potent toxicity, which prevents its expression as a recombinant protein in Escherichia coli.

Pasteurella multocida toxin is a potent activator of anti-apoptotic signalling pathways.

Toxigenic Pasteurella multocida strains produce a 146 kDa protein toxin (PMT) that due to its high mitogenic activity is thought to possess carcinogenic properties. PMT affects several signal transduction pathways related to cancer by constitutively stimulating heterotrimeric G proteins. Downstream of Galpha(q), Galpha(13) and Galpha(i), the toxin activates the small GTPase RhoA, MAP kinases and signal transducer and activator of transcription (STAT) proteins.

Pleiotropic role of Rac in mast cell activation revealed by a cell permeable Bordetella dermonecrotic fusion toxin.

To activate the GTPase Rac in rat basophilic leukemia (RBL) cells and mouse bone marrow-derived mast cells (BMMC) a TAT fusion toxin of Bordetella dermonecrotic toxin (DNT-TAT) was constructed. The fusion toxin activated Rac1 and RhoA in vitro but only Rac in RBL cells and BMMC. DNT-TAT caused an increase in inositol phosphate formation, calcium mobilization, ERK activation and degranulation of mast cells.

Pasteurella multocida toxin activates various heterotrimeric G proteins by deamidation.

Pasteurella multocida produces a 146-kDa protein toxin (Pasteurella multocida toxin, PMT), which stimulates diverse cellular signal transduction pathways by activating heterotrimeric G proteins. PMT deamidates a conserved glutamine residue of the α-subunit of heterotrimeric G proteins that is essential for GTP-hydrolysis, thereby arresting the G protein in the active state. The toxin substrates are Gα(q) Gα(13) and the Gα(i)-family proteins.

Pasteurella multocida toxin activation of heterotrimeric G proteins by deamidation.

Pasteurella multocida toxin is a major virulence factor of Pasteurella multocida, which causes pasteurellosis in men and animals and atrophic rhinitis in rabbits and pigs. The approximately 145 kDa protein toxin stimulates various signal transduction pathways by activating heterotrimeric G proteins of the Galpha(q), Galpha(i), and Galpha(12/13) families by using an as yet unknown mechanism. Here, we show that Pasteurella multocida toxin deamidates glutamine-205 of Galpha(i2) to glutamic acid.

Pasteurella multocida toxin activates Gbetagamma dimers of heterotrimeric G proteins.

The mitogenic Pasteurella multocida toxin (PMT) is a major virulence factor of P. multocida, which causes Pasteurellosis in man and animals. The toxin activates the small GTPase RhoA, the MAP kinase ERK and STAT proteins via the stimulation of members of two G protein families, G(q) and G(12/13).

Activation of Galpha (i) and subsequent uncoupling of receptor-Galpha(i) signaling by Pasteurella multocida toxin.

Bacterial protein toxins are powerful tools for elucidating signaling mechanisms in eukaryotic cells. A number of bacterial protein toxins, e.g.

Action of Pasteurella multocida toxin on Galpha(q) is persistent and independent of interaction with G-protein-coupled receptors.

Pasteurella multocida toxin (PMT) activates Galpha(q) and facilitates stimulation of inositol phosphate accumulation induced by agonists via G(q)-coupled membrane receptors. Here, we studied the effects of PMT on agonist-induced GTPgammaS binding to G(q) in cell membranes and a role of G-protein-coupled receptors in the action of PMT. Pre-treatment of Swiss 3T3 cells with PMT increased bombesin or vasopressin-induced GTPgammaS-binding in cell membranes by about 50 to 150%.

Modulation of host cell gene expression through activation of STAT transcription factors by Pasteurella multocida toxin.

The Pasteurella multocida toxin (PMT) is highly mitogenic and has potential carcinogenic properties. PMT causes porcine atrophic rhinitis that is characterized by bone resorption and loss of nasal turbinates, but experimental nasal infection also leads to excess proliferation of bladder epithelial cells. PMT acts intracellularly and activates phospholipase C-linked signals and MAPK pathways via the heterotrimeric Galpha(q) and Galpha(12/13) proteins.

Pasteurella multocida toxin-induced activation of RhoA is mediated via two families of G{alpha} proteins, G{alpha}q and G{alpha}12/13.

Pasteurella multocida toxin (PMT) is a potent mitogen, which is known to activate phospholipase Cbeta by stimulating the alpha-subunit of the heterotrimeric G protein G(q). PMT also activates RhoA and RhoA-dependent pathways. Using YM-254890, a specific inhibitor of G(q/11), we studied whether activation of RhoA involves G proteins other than G(q/11).

Action of Pasteurella multocida toxin depends on the helical domain of Galphaq.

Pasteurella multocida produces a 146-kDa protein toxin (PMT), which activates multiple cellular signal transduction pathways, resulting in the activation of phospholipase Cbeta, RhoA, Jun kinase, and extracellular signal-regulated kinase. Using Galpha(q)/Galpha(11) -deficient cells, it was shown that the PMT-induced pleiotropic effects are mediated by Galpha(q) but not by the highly related Galpha(11) protein (Zywietz, A., Gohla, A.