Extracellular ATP Regulates Cell Death of Lymphocytes and Monocytes Induced by Membrane‐Bound Lipoproteins of <i>Mycoplasma fermentans</i> and <i>Mycoplasma salivarium</i>

Into, Takeshi; Okada, Kazutaka; Inoue, Nozomu; Yasuda, Motoaki; Shibata, Kenichiro

doi:10.1111/j.1348-0421.2002.tb02750.x

Cited by 24 publications

(17 citation statements)

References 43 publications

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“…A number of studies have shown that T cells can release ATP in response to various extracellular stimuli, suggesting that purinergic signalling may indeed play an active role in T cell activation 8, 80, 81 . T cells express many members of the P2X, P2Y, and P1 receptor families as well as ENTPD1 82-84 .…”

Section: Purinergic Activation Of Immune Cell Responsesmentioning

confidence: 99%

Immune cell regulation by autocrine purinergic signalling

2011

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Preface Purinergic signalling regulates a wide range of cellular processes. Stimulation of virtually any mammalian cell type leads to the release of cellular ATP and autocrine feedback through a diverse set of different purinergic receptors. Depending on the types of purinergic receptors that are involved, autocrine signalling can promote or inhibit cell activation and fine-tune functional responses. Recent work has shown that autocrine signalling is an important checkpoint in immune cell activation that allows cells to adjust their functional responses based on extracellular cues provided by their environment.

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Section: Purinergic Activation Of Immune Cell Responsesmentioning

confidence: 99%

Immune cell regulation by autocrine purinergic signalling

2011

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“…Into and coworkers found that lipoproteins of Mycoplasma fermentans and Mycoplasma salivarius induced an increase in plasma membrane permeability by which ATP is released. This extracellular ATP regulates the cytotoxicity of the lipoproteins, probably by interaction with ATP receptors such as P2X purinergic receptors (15). It has been demonstrated that extracellular ATP has profound effects on cellular functions, causing plasma membrane depolarization, Ca 2ϩ influx, and cell death (6,41).…”

Section: Discussionmentioning

confidence: 99%

OppA, the Substrate-Binding Subunit of the Oligopeptide Permease, Is the Major Ecto-ATPase ofMycoplasma hominis

Miriam

Henrich

2004

J Bacteriol

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Most ATPases, involved in energy-driven processes, act in the cytoplasm. However, external membranebound ATPases have also been described in parasites and eukaryotic cells. In Mycoplasma hominis, a bacterium lacking a cell wall, the surface-exposed substrate-binding protein OppA of an oligopeptide permease (Opp) contains an ATP binding P-loop structure in the C-terminal region. With ATP affinity chromatography and tryptic digestion in the presence or absence of ATP, the functionality of the Mg 2؉ -dependent ATP binding site is demonstrated. In addition to ATP, ADP also could bind to OppA. The presence of an ATPase activity on the surface of M. hominis is indicated by the inactivation of ATP hydrolyzing activity of intact mycoplasma cells by the impermeable ATPase inhibitor 4,4-diisothiocyanostilbene-2,2-disulfonic acid and influenced by the ATP analog 5-fluorosulfonyl-benzoyladenosine. Comparing equimolar amounts of OppA in intact mycoplasma cells and in the purified form indicated that more than 80% of the surface-localized ATPase activity is derived from OppA, implying that OppA is the main ATPase on the surface of mycoplasma cells. Together, these data present the first evidence that the cytoadhesive substrate binding protein OppA of the oligopeptide permease also functions as an ecto-ATPase in Mycoplasma hominis.The most important high-energy phosphate compounds in living cells are adenosine and guanosine triphosphate (ATP and GTP), which serve as carriers of energy that keeps the organism alive. The mobilization of energy is accomplished by a diverse variety of ATPases (31). In 1982, Walker and coworkers (44) described a sequence similarity in the alpha-and beta-subunits of ATP synthetase. This consensus sequence is also found in myosin, kinases, and other ATP-requiring enzymes. The best conserved of these motifs is a glycine-rich region, [AG]-X(4)-G-K- [ST], which typically forms a flexible loop between a beta-strand and an alpha-helix and interacts extensively with the ␤-and ␥-phosphates of the nucleotide, whereas only limited interactions engaged with the ATP adenine ring. This sequence motif, which is generally referred to as Walker A sequence or P-loop, is present in numerous ATP-or GTP-binding proteins, including the nucleotide-binding subunits of the well known ATP-binding cassette (ABC) transporter.Besides the highly conserved Walker A motif there is also a less conserved Walker B motif that is involved in attacking the ␥-phosphate bond during ATP hydrolysis. Consequently, substitution in the Walker sequences generally impairs ATP hydrolysis to a greater or lesser extent (38). Besides the two hydrophilic peripheral nucleotide-binding subunits, ABC transporters generally consist of two hydrophobic membranespanning subunits and a substrate-binding protein which has been described only in bacteria (1, 12). In gram negative bacteria the substrate-binding protein is located within the periplasmic space, whereas in gram positive bacteria it is surface exposed and tethered to the membrane via a lipid ancho...

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“…However, the exact molecular pathogenesis of M. genitalium is vague [7]. It has been suggested that during mycoplasmal infection, the damage to host cells is not caused by direct lesion but by immunopathogenesis [8–10]. Lipoproteins (LPs) are important proteins exposed on the surface of M. genitalium .…”

Section: Introductionmentioning

confidence: 99%

Mycoplasma genitalium Lipoproteins Induce Human Monocytic Cell Expression of Proinflammatory Cytokines and Apoptosis by Activating Nuclear Factor κB

Qiu

Zeng

et al. 2008

Mediators of Inflammation

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This study was designed to investigate the molecular mechanisms responsible for the induction of proinflammatory cytokines gene expression and apoptosis in human monocytic cell line THP-1 stimulated by lipoproteins (LPs) prepared from Mycoplasma genitalium. Cultured cells were stimulated with M. genitalium LP to analyze the production of proinflammatory cytokines and expression of their mRNA by ELISA and RT-PCR, respectively. Cell apoptosis was also detected by Annexin V-FITC-propidium iodide (PI) staining and acridine orange (AO)-ethidium bromide (EB) staining. The DNA-binding activity of nuclear factor-κB (NF-κB) was assessed by electrophoretic mobility shift assay (EMSA). Results showed that LP stimulated THP-1 cells to produce tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 in a dose-dependent manner. The mRNA levels were also upregulated in response to LP stimulation. LPs were also found to increase the DNA-binding activity of NF-κB, a possible mechanism for the induction of cytokine mRNA expression and the cell apoptosis. These effects were abrogated by PDTC, an inhibitor of NF-κB. Our results indicate that M. genitalium-derived LP may be an important etiological factor of certain diseases due to the ability of LP to produce proinflammatory cytokines and induction of apoptosis, which is probably mediated through the activation of NF-κB.

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Extracellular ATP Regulates Cell Death of Lymphocytes and Monocytes Induced by Membrane‐Bound Lipoproteins of Mycoplasma fermentans and Mycoplasma salivarium

Cited by 24 publications

References 43 publications

Immune cell regulation by autocrine purinergic signalling

Immune cell regulation by autocrine purinergic signalling

OppA, the Substrate-Binding Subunit of the Oligopeptide Permease, Is the Major Ecto-ATPase ofMycoplasma hominis

Mycoplasma genitalium Lipoproteins Induce Human Monocytic Cell Expression of Proinflammatory Cytokines and Apoptosis by Activating Nuclear Factor κB

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