Browsing by Subject "P2X7"

Now showing 1 - 7 of 7
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    Amino acid residues in the P2X7 receptor that mediate differential sensitivity to ATP and BzATP
    (American Society for Pharmacology and Experimental Therapeutics, 2007) Young, Mark T.; Pelegrin, Pablo; Surprenant, Annmarie; Bioquímica y Biología Molecular B e Inmunología
    Agonist properties of the P2X7 receptor (P2X7R) differ strikingly from other P2X receptors in two main ways: high concentrations of ATP (> 100 microM) are required to activate the receptor, and the ATP analog 2',3'-O-(4-benzoyl-benzoyl)ATP (BzATP) is both more potent than ATP and evokes a higher maximum current. However, there are striking species differences in these properties. We sought to exploit the large differences in ATP and BzATP responses between rat and mouse P2X7R to delineate regions or specific residues that may be responsible for the unique actions of these agonists at the P2X7R. We measured membrane currents in response to ATP and BzATP at wild-type rat and mouse P2X7R, at chimeric P2X7Rs, and at mouse P2X7Rs bearing point mutations. Wild-type rat P2X7R was 10 times more sensitive to ATP and 100 times more sensitive to BzATP than wild-type mouse P2X7R. We found that agonist EC50 values were determined solely by the ectodomain of the P2X7R. Two segments (residues 115-136 and 282-288), when transposed together, converted mouse sensitivities to those of rat. Point mutations through these regions revealed a single residue, asparagine284, in the rat P2X7R that fully accounted for the 10-fold difference in ATP sensitivity, whereas the 100-fold difference in BzATP sensitivity required the transfer of both Lys127 and Asn284 from rat to mouse. Thus, single amino acid differences between species can account for large changes in agonist effectiveness and differentiate between the two widely used agonists at P2X7 receptors.
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    CD14 release induced by P2X7 receptor restrict inflammation and increases survival during sepsis
    (eLife Sciences Publications, 2020-11-26) Alarcón-Vila, Cristina; Baroja-Mazo, Alberto; Torre-Minguela, Carlos de; Martínez-García, Juan J.; Martínez-Banaclocha, Helios; Gracia-Palenciano, Carlos; Martínez Cáceres, Carlos Manuel; Pelegrín Vivancos, Pablo; Bioquímica y Biología Molecular B e Inmunología
    P2X7 receptor activation induces the release of different cellular proteins, such as CD14, a glycosylphosphatidylinositol (GPI)-anchored protein to the plasma membrane important for LPS signaling via TLR4. Circulating CD14 has been found at elevated levels in sepsis, but the exact mechanism of CD14 release in sepsis has not been established. Here we show for first time that P2X7 receptor induces the release of CD14 in extracellular vesicles, resulting in a net reduction in macrophage plasma membrane CD14 that functionally affects LPS, but not monophosphoryl lipid A, pro-inflammatory cytokine production. Also, we found that during a murine model of sepsis, P2X7 receptor activity is important for maintaining elevated levels of CD14 in biological fluids and a decrease in its activity results in higher bacterial load and exacerbated organ damage, ultimately leading to premature deaths. Our data reveal that P2X7 is a key receptor for helping to clear sepsis because it maintains elevated concentrations of circulating CD14 during infection.
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    Extracellular ATP activates the NLRP3 inflammasome and is an early danger signal of skin allograft rejection
    (Elsevier, 2017-12-19) Amores Iniesta, Joaquín; Barberá Cremades, María; Parrilla, Pascual; Baroja Mazo, Alberto; Martínez Cáceres, Carlos Manuel; Pelegrín Vivancos, Pablo; Anatomía y Anatomía Patológica Comparadas
    Immune cells are equipped with a number of receptors that recognize sterile injury and pathogens. We find that host immune cells release ATP as an inflammatory signal in response to allogeneic transplantation. ATP then acts via a feedback mechanism on the P2X7 channel to activate the NLRP3 inflammasome and subsequently process and release interleukin (IL)-18. This process is a necessary stage in the deleterious Th1 response against allotransplantation via interferon-γ production. Lack of IL-18 resulted in a decrease in graft-infiltrating CD8 cells but an increase in regulatory T cells. In human liver transplant patients undergoing progressive immunosuppressive drug withdrawal, we found that patients experiencing acute rejection had higher levels of the P2X7 receptor in circulating inflammatory monocytes compared to tolerant patients. These data suggest that the pharmacological inhibition of the P2X7 receptor or the NLRP3 inflammasome will aid in inducing transplant tolerance without complete immunoparalysis.
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    P2X7 receptor activation impairs antitumour activity of natural killer cells
    (Wiley, 2022) Baroja-Mazo, Alberto; Peñín-Franch, Alejandro; Lucas-Ruiz, Fernando; Torre-Minguela, Carlos de; Alarcón-Vila, Cristina; Hernández Caselles, Trinidad; Pelegrín Vivancos, Pablo; Bioquímica y Biología Molecular B e Inmunología
    Background and purpose: A high number of intratumoural infiltrating natural killer (NK) cells is associated with better survival in several types of cancer, constituting an important first line of defence against tumours. Hypoxia in the core of solid tumours induces cellular stress and ATP release into the extracellular space where it triggers purinergic receptor activation on tumour-associated immune cells. The aim of this study was to assess whether activation of the purinergic receptor P2X7 by extracellular ATP plays a role in the NK cells antitumour activity. Experimental approach: We carried out in vitro experiments using purified human NK cells triggered through P2X7 by extracellular ATP. NK cell killing activity against the tumour target cells K562 was studied by means of NK cytotoxicity assays. Likewise, we designed a subcutaneous solid tumour in vivo mouse model. Key results: In this study we found that human NK cells, expressing a functional plasma membrane P2X7, acquired an anergic state after ATP treatment, which impaired their antitumour activity and decreased IFN-γ secretion. This effect was reversed by specific P2X7 antagonists and pretreatment with either IL-2 or IL-15. Furthermore, genetic P2rx7 knockdown resulted in improved control of tumour size by NK cells. In addition, IL-2 therapy restored the ability of NK cells to diminish the size of tumours. Conclusions and implications: Our results show that P2X7 activation represents a new mechanism whereby NK cells may lose antitumour effectiveness, opening the possibility of generating modified NK cells lacking P2X7 but with improved antitumour capacity.
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    P2X7 Receptor-Dependent Intestinal Afferent Hypersensitivity in a Mouse Model of Postinfectious Irritable Bowel Syndrome
    (Sociedad Americana de Inmunología, 2011) Keating, Christopher; Pelegrin, Pablo; Grundy, David; Martínez Cáceres, Carlos Manuel; Bioquímica y Biología Molecular B e Inmunología
    The ATP-gated P2X7 receptor (P2X7R) was shown to be an important mediator of inflammation and inflammatory pain through its regulation of IL-1 processing and release. Trichinella spiralis-infected mice develop a postinflammatory visceral hypersensitivity that is reminiscent of the clinical features associated with postinfectious irritable bowel syndrome. In this study, we used P2X7R knockout mice (P2X7R–/–) to investigate the role of P2X7R activation in the in vivo production of IL-1 and the development of postinflammatory visceral hypersensitivity in the T. spiralis-infected mouse. During acute nematode infection, IL-1–containing cells and P2X7R expression were increased in the jejunum of wild-type (WT) mice. Peritoneal and serum IL-1 levels were also increased, which was indicative of elevated IL-1 release. However, in the P2X7R–/– animals, we found that infection had no effect upon intracellular, plasma, or peritoneal IL-1 levels. Conversely, infection augmented peritoneal TNF- levels in both WT and P2X7R–/– animals. Infection was also associated with a P2X7R-dependent increase in extracellular peritoneal lactate dehydrogenase, and it triggered immunological changes in both strains. Jejunal afferent fiber mechanosensitivity was assessed in uninfected and postinfected WT and P2X7R–/– animals. Postinfected WT animals developed an augmented afferent fiber response to mechanical stimuli; however, this did not develop in postinfected P2X7R–/– animals. Therefore, our results demonstrated that P2X7Rs play a pivotal role in intestinal inflammation and are a trigger for the development of visceral hypersensitivity.
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    Potential role of P2X7 receptor in neurodegenerative processes in a murine model of glaucoma
    (Elsevier, 2019) Pérez de Lara, María J.; Avilés Trigueros, Marcelino; Guzmán-Aránguez, Ana; Valiente Soriano, Francisco Javier; de la Villa, Pedro; Vidal-Sanz, Manuel; Pintor, Jesús; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    Glaucoma is a common cause of visual impairment and blindness, characterized by retinal ganglion cell (RGC) death. The mechanisms that trigger the development of glaucoma remain unknown and have gained significant relevance in the study of this neurodegenerative disease. P2X7 purinergic receptors (P2X7R) could be involved in the regulation of the synaptic transmission and neuronal death in the retina through different pathways. The aim of this study was to characterize the molecular signals underlying glaucomatous retinal injury. The time-course of functional, morphological, and molecular changes in the glaucomatous retina of the DBA/2J mice were investigated. The expression and localization of P2X7R was analysed in relation with retinal markers. Caspase-3, JNK, and p38 were evaluated in control and glaucomatous mice by immunohistochemical and western-blot analysis. Furthermore, electroretinogram recordings (ERG) were performed to assess inner retina dysfunction. Glaucomatous mice exhibited changes in P2X7R expression as long as the pathology progressed. There was P2X7R overexpression in RGCs, the primary injured neurons, which correlated with the loss of function through ERG measurements. All analyzed MAPK and caspase-3 proteins were upregulated in the DBA/2J retinas suggesting a pro-apoptotic cell death. The increase in P2X7Rs presence may contribute, together with other factors, to the changes in retinal functionality and the concomitant death of RGCs. These findings provide evidence of possible intracellular pathways responsible for apoptosis regulation during glaucomatous degeneration.
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    Role of acupuncture in improving the outcome of sepsis-induced lung injury
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Li, Peng; Li, Fangfang; Chen, Si; Ma, Qiulei; Wang, Jie; Ma, Bingquan; Xu, Jin
    Objective. The purpose of this study was to investigate the effect of serum exosomes of mice after acupuncture (acu-exo) on acute lung injury (ALI) in sepsis in vitro and in vivo. Methods. Serum exosomes (acu-exo) of normal mice were prepared after acupuncture. Lipopolysaccharide (LPS) was used to establish the model of ALI in vivo and in vitro. Immunohistochemistry, western blot, and immunofluorescence were used to evaluate the mechanism of acu-exo on ALI. P2X7 knockout mice and P2X7 siRNA were used to verify the mechanism. Results. Compared with normal mice, serum exosomes were significantly increased in normal mice after acupuncture. The results showed that P2X7 was increased in the lung of septic mice as compared with the WT group. It was also found that the increase in NLRP3 and NF-κB was accompanied by the activation of P2X7. Increased P2X7 led to activation of the P2X7 receptor causing mitochondrial dysfunctions in lung tissue of septic mice. Knockout of P2X7 or silenced P2X7 markedly decreased NLRP3 and NF-κB and led to mitochondrial function recovery in lung tissue of sepsis. At the same time, acu-exo significantly restored the above changes in the lung tissue of septic mice. Conclusions. Inhibition of P2X7 led to mito-chondrial function recovery of lung tissue by inhibiting NLRP3 and NF-κB. At the same time, acu-exo could improve ALI by decreasing NLRP3 and NF-κB activation