Purinergic Signalling最新文献

Purinergic signaling regulates many metabolic functions and is implicated in liver physiology and pathophysiology. Liver functionality is modulated by ionotropic P2X and metabotropic P2Y receptors, specifically P2Y1, P2Y2, and P2Y6 subtypes, which physiologically exert their influence through calcium signaling, a key second messenger controlling glucose and fat metabolism in hepatocytes. Purinergic receptors, acting through calcium signaling, play an important role in a range of liver diseases. Ionotropic P2X receptors, such as the P2X7 subtype, and certain metabotropic P2Y receptors can induce aberrant intracellular calcium transients that impact normal hepatocyte function and initiate the activation of other liver cell types, including Kupffer and stellate cells. These P2Y- and P2X-dependent intracellular calcium increases are particularly relevant in hepatic disease states, where stellate and Kupffer cells respond with innate immune reactions to challenges, such as excess fat accumulation, chronic alcohol abuse, or infections, and can eventually lead to liver fibrosis. This review explores the consequences of excessive extracellular ATP accumulation, triggering calcium influx through P2X4 and P2X7 receptors, inflammasome activation, and programmed cell death. In addition, P2Y2 receptors contribute to hepatic steatosis and insulin resistance, while inhibiting the expression of P2Y6 receptors can alleviate alcoholic liver steatosis. Adenosine receptors may also contribute to fibrosis through extracellular matrix production by fibroblasts. Thus, pharmacological modulation of P1 and P2 receptors and downstream calcium signaling may open novel therapeutic avenues.

Ongoing cardiac remodeling can lead to negative outcomes, such as cardiac failure and diminished myocardial function, although the remodeling process initially protects the heart as a compensatory mechanism[1] . Importantly, ferroptosis appears to be a critical process in the development of cardiac disease. In a recent publication in Redox Biology, (Zhong et al. [2] showed that reactive oxygen species (ROS) generation and cardiac ferroptosis may be the mechanisms underlying angiotensin II (Ang II)-induced cardiac remodeling, as well as that ferroptosis is required for heart impairment and cardiac dysfunction induced by Ang II. Moreover, this study provides evidence that Ang II increases the expression of P2X7 receptors (P2X7R) in cardiac tissues and that both silencing and pharmacological inhibition of P2X7R significantly inhibited Ang II-induced ferroptosis and hypertrophy. Also, this work confirmed that P2X7R deficiency mitigated the Ang II-induced deterioration of cardiac injury in mice fed an iron-rich diet. Most interestingly, this study revealed that Ang II directly interacts with the P2X7R to activate and induce nucleocytoplasmic shuttling of human antigen R (HuR), which in turn controls the stability of the mRNA of heme oxygenase 1 (HO-1) and GPX4 and subsequent ROS production, which translated to induction of myocardial ferroptosis and remodeling.

Moxibustion, traditional Chinese medicine treatment, involves the warming of specific acupuncture points of the body using ignited herbal materials. Evidence suggests beneficial effects of moxibustion in several brain diseases including epilepsy, however, whether moxibustion pretreatment impacts on seizures and what are the underlying mechanisms remains to be established. Evidence has suggested the purinergic ATP-gated P2X7 receptor (P2X7R) to be involved in the actions of moxibustion. Moreover, P2X7R signalling is now well established to contribute to long-lasting brain hyperexcitability underlying epilepsy development. Whether P2X7R signalling is involved in the seizure-reducing actions of moxibustion has not been investigated to date. For our studies we used C57BL/6 male mice that received moxibustion pre-treatments at the acupoints Zusanli (ST36) and Dazhui (GV14) once daily for either 7, 14, or 21 days. This was followed by an intraperitoneal injection of kainic acid (KA, 30 mg/kg) to induce status epilepticus. Behavioral changes during KA-induced status epilepticus were analyzed according to the Racine scale. Changes in electrographic seizures were analyzed via cortical implanted electroencephalogram (EEG) electrodes. While no effect on seizure severity was observed following 7 days of moxibustion pre-treatment, moxibustion pre-treatment at both ST36 and GV14 for 14 or 21 days significantly reduced KA-induced behavior seizures at a similar rate. Cortical EEG recordings showed that 14 days of moxibustion pre-treatments also reduced electrographic seizures, confirming the anticonvulsant actions of moxibustion pre-treatment. To determine whether moxibustion impacts the pro-convulsant actions of P2X7R signaling, mice were treated with the P2X7R agonist BzATP or P2X7R antagonist A438079. While treatment with the P2X7R agonist BzATP exacerbated seizure severity, treatment with the P2X7R antagonist reduced seizure severity. We further found that moxibustion pre-treatment attenuated epileptic seizures by counteracting the effects of BzATP. These results suggest that moxibustion pre-treatment at the acupoints ST36 and GV14 for 14 days has anti-epileptic effects, which may counteract the proconvulsant functions of the P2X7R.

The mechanism of neuropathic pain induced by nerve injury is complex and there are no effective treatment methods. P2X4 receptor expression is closely related to the occurrence of pain. Schwann cells (SCs) play a key protective role in the repair of peripheral nerve injury and myelin sheath regeneration. However, whether SCs can affect the expression of P2X4 receptor and play a role in pathological pain is still unclear. Therefore, this study investigated the effect of SCs on whether they can down regulate the expression of P2X4 receptor to affect pain. The results showed that in the neuropathic pain induced by sciatic nerve injury model, the expression of P2X4 receptor in spinal cord tissue was significantly increased and the pain sensation of rats was increased. While SCs transplantation could down regulate the expression of P2X4 receptors in spinal cord and increase the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of rats. These data indicate that SCs can reduce the expression of P2X4 receptors to alleviate neuropathic pain, indicating that SCs can mediate P2X4 receptor signalling as a new target for pain treatment.

P2X7 receptor (P2X7R) has been found to contribute to the peripheral mechanism of acupuncture analgesia (AA). However, whether it plays an important role in central mechanism remains unknown. In this study, we aimed to reveal the role of astrocytic P2X7R in retrosplenial cortex (RSC) in AA and provide new evidence for underlying the central mechanism of AA. We applied the chemogenetic receptors hM3Dq to stimulate or hM4Di to inhibit astrocytes ligand clozapine-N-oxide (CNO) following injection of adeno-associated virus (AAV) into the bilateral RSC, or pharmacologically intervened in the activity of the purinergic receptor P2X7R. Current data indicated that chemogenetic inhibition of astrocytes or injection of P2X7R agonist Bz-ATP in the bilateral RSC significantly reverses the analgesic effect of electroacupuncture (EA) in formalin tests while the bilateral injection of the P2X7R antagonist A438079 alleviated formalin-induced nociceptive behavior. Additionally, chemogenetic suppression of astrocytic P2X7R by injection of AAV in the bilateral RSC decreased hind paw flinches induced by formalin in the mice. These findings indicate the participation of both astrocytes and P2X7R in the RSC in EA analgesic. Moreover, P2X7R on astrocytes in the RSC appears to play a critical role in the ability of EA to attenuate formalin-induced pain responses in mice.

Cardiovascular diseases (CVDs), including hypertension, atherosclerosis, myocardial ischemia, and myocardial infarction, constitute the primary cause of mortality worldwide. Transcription factors play critical roles in the development of CVDs and contribute to the pathophysiology of these diseases by coordinating the transcription of many genes involved in inflammation, oxidative stress, angiogenesis, and glycolytic metabolism. One important regulator of hemostasis in both healthy and pathological settings has been identified as a purinergic signalling pathway. Research has demonstrated that several signalling networks implicated in the pathophysiology of CVDs are formed by transcription factors that are regulated by purinergic substances. Here, we briefly summarize the roles and mechanisms of the transcription factors regulated by purinergic pathways in various types of CVD. This information will be essential for discovering novel approaches for CVD treatment and prevention.

Adenosine receptor (AR) suppresses inflammation and fibrosis by activating cyclic adenosine monophosphate (cAMP) signaling. We investigated whether altered AR expression contributes to the development of fibrotic diseases and whether A_2AAR and A_2BAR upregulation inhibits fibrotic responses. Primary human lung fibroblasts (HLFs) from normal (NHLFs) or patients with idiopathic pulmonary fibrosis (DHLF) were used for in vitro testing. Murine models of fibrotic liver or pulmonary disease were developed by injecting thioacetamide intraperitoneally, by feeding a high-fat diet, or by intratracheal instillation of bleomycin. Modafinil, which activates cAMP signaling via A_2AAR and A_2BAR, was administered orally. The protein amounts of A_2AAR, A_2BAR, and exchange protein directly activated by cAMP (Epac) were reduced, while collagen and α-smooth muscle actin (α-SMA) were elevated in DHLFs compared to NHLFs. In liver or lung tissue from murine models of fibrotic diseases, A_2AAR and A_2BAR were downregulated, but A₁AR and A₃AR were not. Epac amounts decreased, and amounts of collagen, α-SMA, K_Ca2.3, and K_Ca3.1 increased compared to the control. Modafinil restored the amounts of A_2AAR, A_2BAR, and Epac, and reduced collagen, α-SMA, K_Ca2.3, and K_Ca3.1 in murine models of fibrotic diseases. Transforming growth factor-β reduced the amounts of A_2AAR, A_2BAR, and Epac, and elevated collagen, α-SMA, K_Ca2.3, and K_Ca3.1 in NHLFs; however, these alterations were inhibited by modafinil. Our investigation revealed that A_2AAR and A_2BAR downregulation induced liver and lung fibrotic diseases while upregulation attenuated fibrotic responses, suggesting that A_2AAR and A_2BAR-upregulating agents, such as modafinil, may serve as novel therapies for fibrotic diseases.

This study was designed to investigate the potential of extracellular adenosine 5'-triphosphate (ATP) via the P2 X 7 receptor to activate the renal fibrotic processes in rats. The present study demonstrates that administration of ATP rapidly activated transforming growth factor-β (TGF-β) to induce phosphorylation of Smad-2/3. Renal connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA and protein expressions were also increased following ATP administration. A decrease in TGF-β amount in serum as well as renal Smad-2/3 phosphorylation was noticed in animals pre-treated with the specific antagonist of P2 X 7 receptor, A 438,079. In addition, a significant reduction in mRNA and protein expression of CTGF and TIMP-1were also observed in the kidneys of those animals. Collectively, the current findings demonstrate that ATP has the ability to augment TGF-β-mediated Smad-2/3 phosphorylation and enhance the expression of the pro-fibrotic genes, CTGF and TIMP-1, an effect that is largely mediated via P2 X 7 receptor.