RESUMO
The renin-angiotensin system (RAS) plays a key role in blood pressure regulation. The RAS is a complex interconnected system composed of two axes with opposite effects. The pressor arm, represented by angiotensin (Ang) II and the AT1 receptor (AT1R), mediates the vasoconstrictor, proliferative, hypertensive, oxidative, and pro-inflammatory effects of the RAS, while the depressor/protective arm, represented by Ang-(1-7), its Mas receptor (MasR) and the AT2 receptor (AT2R), opposes the actions elicited by the pressor arm. The AT1R, AT2R, and MasR belong to the G-protein-coupled receptor (GPCR) family. GPCRs operate not only as monomers, but they can also function in dimeric (homo and hetero) or higher-order oligomeric states. Due to the interaction with other receptors, GPCR properties may change: receptor affinity, trafficking, signaling, and its biological function may be altered. Thus, heteromerization provides a newly recognized means of modulation of receptor function, as well as crosstalk between GPCRs. This review is focused on angiotensin receptors, and how their properties are influenced by crosstalk with other receptors, adding more complexity to an already complex system and potentially opening up new therapeutic approaches.
Assuntos
Receptores Acoplados a Proteínas G , Sistema Renina-Angiotensina , Humanos , Sistema Renina-Angiotensina/fisiologia , Animais , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/fisiologia , Receptor Cross-Talk/fisiologia , Receptores de Angiotensina/metabolismo , Receptor Tipo 1 de Angiotensina/metabolismo , Pressão Sanguínea/fisiologia , Receptor Tipo 2 de Angiotensina/metabolismoRESUMO
Schizophrenia (SZ) is a multifactorial disorder characterized by volume reduction in gray and white matter, oxidative stress, neuroinflammation, altered neurotransmission, as well as molecular deficiencies such as punctual mutation in DisruptedinSchizophrenia 1 protein. In this regard, it is essential to understand the underlying molecular disturbances to determine the pathophysiological mechanisms of the disease. The signaling pathways activated by G proteincoupled receptors (GPCRs) are key molecular signaling pathways altered in SZ. Convenient models need to be designed and validated to study these processes and mechanisms at the cellular level. Cultured olfactory stem cells are used to investigate neural molecular and cellular alterations related to the pathophysiology of SZ. Multipotent human olfactory stem cells are undifferentiated and express GPCRs involved in numerous physiological functions such as proliferation, differentiation and bioenergetics. The use of olfactory stem cells obtained from patients with SZ may identify alterations in GPCR signaling that underlie dysfunctional processes in both undifferentiated and specialized neurons or derived neuroglia. The present review aimed to analyze the role of GPCRs and their signaling in the pathophysiology of SZ. Culture of olfactory epithelial cells constitutes a suitable model to study SZ and other psychiatric disorders at the cellular level.
Assuntos
Esquizofrenia , Humanos , Esquizofrenia/genética , Esquizofrenia/metabolismo , Células Neuroepiteliais/metabolismo , Neurônios/metabolismo , Receptores Acoplados a Proteínas G , Células-Tronco/metabolismoRESUMO
ABSTRACT Background: Bile acids (BAs) are steroid molecules synthesized exclusively in the liver, being end products of cholesterol catabolism. BAs are known to be involved in several metabolic alterations, including metabolic syndrome and type 2 diabetes mellitus (DM2). DM2 is a chronic degenerative disease characterized by insulin resistance, insulin deficiency due to insufficient production of pancreatic ß-cells, and elevated serum glucose levels leading to multiple complications. Objective: The objective of this study is to investigate the role of BAs in the pathophysiology of DM2, highlighting the possibilities in the development of therapeutic procedures targeting BAs as an optional pathway in the treatment of DM2. Methods: The research was carried out through narrative review and publications on the relationship between BAs and DM2. The databases used for the search include PubMed, Scopus, and Web of Science. The keywords used for the search include bile acids, type 2 diabetes mellitus, metabolic syndrome, and metabolic disorders. Results: The studies have reported the involvement of BAs in the pathophysiology of DM2. BAs act as a ligand for the nuclear farnesoid X receptor, regulating glucose metabolism, lipid metabolism, and cellular energy production. Additionally, BAs modulate the production, elimination, and mobilization of BAs through the farnesoid X receptor. BAs also act as a signaling pathway through Takeda G protein-coupled receptor 5, further contributing to metabolic regulation. These findings suggest that targeting BAs may offer a novel therapeutic approach in the treatment of DM2. Conclusion: This study highlights the important role of BAs in DM2, specifically through their interactions with key metabolic pathways. Targeting BAs may represent an innovative and effective approach to the treatment of DM2.
RESUMO Contexto: Os ácidos biliares (ABs) são moléculas esteróides sintetizadas exclusivamente no fígado, sendo produtos finais do catabolismo do colesterol. Os ABs são conhecidos por estarem envolvidos em várias alterações metabólicas, incluindo a síndrome metabólica e o diabetes mellitus tipo 2 (DM2). A DM2 é uma doença crônica degenerativa caracterizada pela resistência insulínica, deficiência de insulina devido à produção insuficiente de células ß pancreáticas e hiperglicemia levando a múltiplas complicações. Objetivo: O objetivo deste estudo é investigar o papel dos ABs na fisiopatologia da DM2, destacando as possibilidades no desenvolvimento de procedimentos terapêuticos visando os ABs como uma via opcional no tratamento da DM2. Métodos: A pesquisa foi realizada por meio de revisão narrativa e publicações sobre a relação entre ABs e DM2. As bases de dados usadas para a pesquisa incluem PubMed, Scopus e Web of Science. As palavras-chave usadas para a pesquisa incluíram: ácidos biliares, diabetes mellitus tipo 2, síndrome metabólica e distúrbios metabólicos. Resultados: Os estudos relataram o envolvimento dos ABs na fisiopatologia da DM2. Os ABs atuam como ligantes para o receptor nuclear farnesoide X, regulando o metabolismo da glicose, metabolismo lipídico e produção de energia celular. Além disso, os ABs regulam a produção, eliminação e mobilização de ABs através do receptor farnesoide X. Os ABs também atuam como uma via de sinalização através do receptor acoplado à proteína G Takeda 5, contribuindo ainda mais para a regulação metabólica. Esses achados sugerem que o ABs pode oferecer uma nova abordagem terapêutica no tratamento da DM2. Conclusão: Este estudo destaca o papel importante do ABs na DM2, especificamente por meio de suas interações com vias metabólicas-chave. O redirecionamento ao ABs pode representar uma abordagem inovadora e eficaz para o tratamento da DM2.
RESUMO
Adhesion G protein-coupled receptors (aGPCRs) possess a unique topology, including the presence of a GPCR proteolysis site (GPS), which, upon autoproteolysis, generates two functionally distinct fragments that remain non-covalently associated at the plasma membrane. A proposed activation mechanism for aGPCRs involves the exposure of a tethered agonist, which depends on cleavage at the GPS. However, this hypothesis has been challenged by the observation that non-cleavable aGPCRs exhibit constitutive activity, thus making the function of GPS cleavage widely enigmatic. In this study, we sought to elucidate the function of GPS-mediated cleavage through the study of G protein coupling with Latrophilin-3/ADGRL3, a prototypical aGPCR involved in synapse formation and function. Using BRET-based G protein biosensors, we reveal that an autoproteolysis-deficient mutant of ADGRL3 retains constitutive activity. Surprisingly, we uncover that cleavage deficiency leads to a signalling bias directed at potentiating the activity of select G proteins such as Gi2 and G12/13. These data unveil the underpinnings of biased signalling for aGPCRs defined by GPS autoproteolysis.
Assuntos
Receptores Acoplados a Proteínas G , Transdução de Sinais , Relação Estrutura-Atividade , Receptores Acoplados a Proteínas G/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Adesão CelularRESUMO
The renin angiotensin system (RAS) plays a major role in blood pressure regulation and electrolyte homeostasis and is mainly composed by two axes mediating opposite effects. The pressor axis, constituted by angiotensin (Ang) II and the Ang II type 1 receptor (AT1R), exerts vasoconstrictor, proliferative, hypertensive, oxidative and pro-inflammatory actions, while the depressor/protective axis, represented by Ang-(1-7), its Mas receptor (MasR) and the Ang II type 2 receptor (AT2R), opposes the actions elicited by the pressor arm. The MasR belongs to the G protein-coupled receptor (GPCR) family. To avoid receptor overstimulation, GPCRs undergo internalization and trafficking into the cell after being stimulated. Then, the receptor may induce other signaling cascades or it may even interact with other receptors, generating distinct biological responses. Thus, control of a GPCR regarding space and time affects the specificity of the signals transduced by the receptor and the ultimate cellular response. The present chapter is focused on the signaling and trafficking pathways of MasR under physiological conditions and its participation in the pathogenesis of numerous brain diseases.
Assuntos
Endocitose , Proto-Oncogene Mas , Sistema Renina-Angiotensina , Humanos , Angiotensina II/metabolismo , Angiotensina II/farmacologia , Pressão Sanguínea/fisiologia , Proto-Oncogene Mas/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Sistema Renina-Angiotensina/fisiologiaRESUMO
The renin-angiotensin system (RAS) is a classical hormonal system involved in a myriad of cardiovascular functions. This system is composed of many different peptides that act in the heart through different receptors. One of the most important of these peptides is angiotensin II, which in pathological conditions triggers a set of actions that lead to heart failure. On the other hand, another RAS peptide, angiotensin-(1-7) is well known to develop powerful therapeutic effects in many forms of cardiac diseases. In the last decade, two new components of RAS were described, the heptapeptide alamandine and its receptor, the Mas-related G protein-coupled receptor member D (MrgD). Since then, great effort was made to characterize their physiological and pathological function in the heart. In this review, we summarize the latest insights about the actions of alamandine/MrgD axis in the heart, with particular emphasis in the cardiomyocyte. More specifically, we focused on their antihypertrophic and contractility effects, and the related molecular events activated in the cardiomyocyte.
Assuntos
Miócitos Cardíacos , Receptores Acoplados a Proteínas G , Miócitos Cardíacos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Sistema Renina-Angiotensina , Angiotensina II/metabolismo , Angiotensina I/metabolismo , Fragmentos de Peptídeos/metabolismoRESUMO
GPR139 is an orphan G-protein-coupled receptor that is expressed in restricted areas of the nervous system, including the hypothalamus. In this study, we hypothesized that GPR139 could be involved in the regulation of energy balance and metabolism. In the first part of the study, we confirmed that GPR139 is expressed in the hypothalamus and particularly in proopiomelanocortin and agouti-related peptide neurons of the mediobasal hypothalamus. Using a lentivirus with a short-hairpin RNA, we inhibited the expression of GPR139 bilaterally in the mediobasal hypothalamus of mice. The intervention promoted a 40% reduction in the hypothalamic expression of GPR139, which was accompanied by an increase in body mass, a reduction in fasting blood glucose levels, and an increase in insulin levels. In the hypothalamus, inhibition of GPR139 was accompanied by a reduction in the expression of orexin. As previous studies using a pharmacological antagonist of orexin showed a beneficial impact on type 2 diabetes and glucose metabolism, we propose that the inhibition of hypothalamic GPR139 could be acting indirectly through the orexin system to control systemic glucose and insulin. In conclusion, this study advances the characterization of GPR139 in the hypothalamus, demonstrating its involvement in the regulation of body mass, blood insulin, and glycemia.
Assuntos
Diabetes Mellitus Tipo 2 , Insulina , Camundongos , Animais , Orexinas/metabolismo , Insulina/metabolismo , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Hipotálamo/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Proteínas do Tecido Nervoso/metabolismoRESUMO
Activation of nociceptin opioid peptide receptors (NOP, a.k.a. opioid-like receptor-1, ORL-1) by the ligand nociceptin/orphanin FQ, leads to G protein-dependent regulation of Cav2.2 (N-type) voltage-gated calcium channels (VGCCs). This typically causes a reduction in calcium currents, triggering changes in presynaptic calcium levels and thus neurotransmission. Because of the widespread expression patterns of NOP and VGCCs across multiple brain regions, the dorsal horn of the spinal cord, and the dorsal root ganglia, this results in the alteration of numerous neurophysiological features. Here we review the regulation of N-type calcium channels by the NOP-nociceptin system in the context of neurological conditions such as anxiety, addiction, and pain.
Assuntos
Canais de Cálcio Tipo N , Doenças do Sistema Nervoso , Humanos , Analgésicos Opioides , Cálcio , Receptor de NociceptinaRESUMO
Cannabidiol (CBD), the major non-psychoactive phytocannabinoid present in the plant Cannabis sativa, has displayed beneficial pharmacological effects in the treatment of several neurological disorders including, epilepsy, Parkinson's disease, and Alzheimer's disease. In particular, CBD is able to modulate different receptors in the endocannabinoid system, some of which belong to the family of G-protein-coupled receptors (GPCRs). Notably, while CBD is able to antagonize some GPCRs in the endocannabinoid system, it also seems to activate others. The details of this dual contrasting functional feature of CBD, that is, displaying antagonistic and (possible) agonistic ligand properties in related receptors, remain unknown. Here, using computational methods, we investigate the interacting determinants of CBD in two closely related endocannabinoid-activated GPCRs, the G-protein-coupled receptor 55 (GPR55) and the cannabinoid type 1 receptor (CB1). While in the former, CBD has been demonstrated to function as an antagonist, the way by which CBD modulates the CB1 receptor remains unclear. Namely, CBD has been suggested to directly trigger receptor's activation, stabilize CB1 inactive conformations or function as an allosteric modulator. From microsecond-length unbiased molecular dynamics simulations, we found that the presence of the CBD ligand in the GPR55 receptor elicit conformational changes associated with antagonist-bound GPCRs. In contrast, when the GPR55 receptor is simulated in complex with the selective agonist ML186, agonist-like conformations are sampled. These results are in agreement with the proposed modulatory function of each ligand, showing that the computational techniques utilized to characterize the GPR55 complexes correctly differentiate the agonist-bound and antagonist-bound systems. Prompted by these results, we investigated the role of the CBD compound on the CB1 receptor using similar computational approaches. The all-atom MD simulations reveal that CBD induces conformational changes linked with agonist-bound GPCRs. To contextualize the results we looked into the CB1 receptor in complex with a well-established antagonist. In contrast to the CBD/CB1 complex, when the CB1 receptor is simulated in complex with the ligand antagonist AM251, inactive conformations are explored, showing that the computational techniques utilized to characterize the CB1 complexes correctly differentiate the agonist-bound and antagonist-bound systems. In addition, our results suggest a previously unknown sodium-binding site located in the extracellular domain of the CB1 receptor. From our detailed characterization, we found particular interacting loci in the binding sites of the GPR55 and the CB1 receptors that seem to be responsible for the differential functional features of CBD. Our work will pave the way for understanding the CBD pharmacology at a molecular level and aid in harnessing its potential therapeutic use.
RESUMO
Cancer progression relies on cellular transition states accompanied by changes in the functionality of adhesion molecules. The gene for adhesion G protein-coupled receptor latrophilin-3 (aGPCR Lphn3 or ADGRL3) is targeted by tumor-specific somatic mutations predominantly affecting the conserved GAIN domain where most aGPCRs are cleaved. However, it is unclear how these GAIN domain-altering mutations impact Lphn3 function. Here, we studied Lphn3 cancer-related mutations as a proxy for revealing unknown GAIN domain functions. We found that while intra-GAIN cleavage efficiency was unaltered, most mutations produced a ligand-specific impairment of Lphn3 intercellular adhesion profile paralleled by an increase in cell-matrix actin-dependent contact structures for cells expressing the select S810L mutation. Aberrant remodeling of the intermediate filament vimentin, which was found to coincide with Lphn3-induced modification of nuclear morphology, had less impact on the nuclei of S810L expressing cells. Notoriously, receptor signaling through G13 protein was deficient for all variants bearing non-homologous amino acid substitutions, including the S810L variant. Analysis of cell migration paradigms revealed a non-cell-autonomous impairment in collective cell migration indistinctly of Lphn3 or its cancer-related variants expression, while cell-autonomous motility was potentiated in the presence of Lphn3, but this effect was abolished in S810L GAIN mutant-expressing cells. These data identify the GAIN domain as an important regulator of Lphn3-dependent cell motility, thus furthering our understanding of cellular and molecular events linking Lphn3 genetic somatic mutations to cancer-relevant pathogenesis mechanisms.
Assuntos
Movimento Celular , Neoplasias , Receptores Acoplados a Proteínas G , Transdução de Sinais , Substituição de Aminoácidos , Linhagem Celular , Humanos , Mutação , Neoplasias/genética , Domínios Proteicos , Receptores Acoplados a Proteínas G/metabolismo , Receptores de PeptídeosRESUMO
Currently, up to 35% off all drugs approved for the treatment of human diseases belong to the G-protein-coupled receptor (GPCR) family. Out of the almost 800 existing GPCRs, 25% have no known endogenous ligands and are regarded as orphan receptors; many of these are currently under investigation as potential pharmacological targets. Here, we hypothesised that orphan GPCRs expressed in the hypothalamus could be targets for the treatment of obesity and other metabolic diseases. Using bioinformatic tools, we identified 78 class A orphan GPCRs that are expressed in the hypothalamus of mice. Initially, we selected two candidates and determined their responsivities to nutritional interventions: GPR162, the GPCR with highest expression in the hypothalamus, and GPR68, a GPCR with intermediate expression in the hypothalamus and that has never been explored for its potential involvement in metabolic regulation. GPR162 expression was not modified by fasting/feeding or by the consumption of a high-fat diet, and was therefore not subsequently evaluated. Conversely, GPR68 expression increased in response to the consumption of a high-fat diet and reduced under fasting conditions. Using immunofluorescence, GPR68 was identified in both proopiomelanocortin-expressing and agouti-related peptide-expressing neurons in the hypothalamic arcuate nucleus. Acute inhibition of GPR68 with an allosteric modulator promoted an increase in the expression of the orexigenic agouti-related peptide and neuropeptide Y, whereas 4- and 12-h inhibition of GPR68 resulted in increased caloric intake. Thus, GPR68 has emerged as an orphan GPCR that is expressed in the hypothalamus and is involved in the regulation of feeding.
Assuntos
Núcleo Arqueado do Hipotálamo , Hipotálamo , Receptores Acoplados a Proteínas G , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Hipotálamo/metabolismo , Camundongos , Neuropeptídeo Y/metabolismo , Pró-Opiomelanocortina/metabolismo , Receptores Acoplados a Proteínas G/metabolismoRESUMO
BACKGROUND: G protein coupled receptor kinase 2 (GRK2) has been demonstrated to play a crucial role in the development of chronic pain. Acupuncture is an alternative therapy widely used for pain management. In this study, we investigated the role of spinal neuronal GRK2 in electroacupuncture (EA) analgesia. METHODS: The mice model of inflammatory pain was built by subcutaneous injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the hind paws. The mechanical allodynia of mice was examined by von Frey test. The mice were subjected to EA treatment (BL60 and ST36 acupuncture points) for 1 week. Overexpression and downregulation of spinal neuronal GRK2 were achieved by intraspinal injection of adeno associated virus (AAV) containing neuron-specific promoters, and microglial activation and neuroinflammation were evaluated by real-time PCR. RESULTS: Intraplantar injection with CFA in mice induced the decrease of GRK2 and microglial activation along with neuroinflammation in spinal cord. EA treatment increased the spinal GRK2, reduced neuroinflammation, and significantly decreased CFA-induced mechanical allodynia. The effects of EA were markedly weakened by non-cell-specific downregulation of spinal GRK2. Further, intraspinal injection of AAV containing neuron-specific promoters specifically downregulated neuronal GRK2, and weakened the regulatory effect of EA on CFA-induced mechanical allodynia and microglial activation. Meanwhile, overexpression of spinal neuronal GRK2 decreased mechanical allodynia. All these indicated that the neuronal GRK2 mediated microglial activation and neuroinflammation, and subsequently contributed to CFA-induced inflammatory pain. CONCLUSION: The restoration of the spinal GRK2 and subsequent suppression of microglial activation and neuroinflammation might be an important mechanism for EA analgesia. Our findings further suggested that the spinal GRK2, especially neuronal GRK2, might be the potential target for EA analgesia and pain management, and we provided a new experimental basis for the EA treatment of pain.
Assuntos
Eletroacupuntura , Quinase 2 de Receptor Acoplado a Proteína G/fisiologia , Microglia/fisiologia , Manejo da Dor , Animais , Inflamação/induzido quimicamente , Inflamação/terapia , Camundongos , Neurônios , Dor/induzido quimicamenteRESUMO
Neuromedin B (NB), a bombesin-like peptide, exerts its specific actions by binding to the neuromedin B receptor (NBR), a G protein-coupled receptor. Female NBR-knockout (NBR-KO) mice exhibit resistance to diet-induced obesity, without hyperphagia, suggesting possible increase in energy expenditure. Skeletal muscle (SM) is crucial for whole body energy homeostasis, however, the presence of NB-NBR signaling and its effects in SM are unknown. Here, we show that male and female wild type express Nmbr and Nmb mRNA in SM, with higher levels in females. Female NBR-KO gastrocnemius showed increased Myh7 mRNA level, which characterizes type I fibers (oxidative profile). Their permeabilized gastrocnemius fibers, studied by high-resolution respirometry, exhibited higher consumption of O2 coupled to ATP synthesis and unaltered uncoupled respiration. NBR-KO gastrocnemius had higher protein levels of ATP-synthase and Nduf9 mRNA, corresponding to mitochondrial complex I subunit. NBR-KO gastrocnemius exhibited slight increase in mitochondria number, increased thickness of Z line at electron microscopy, and unaltered mitochondrial dynamics markers. Therefore, in the females' gastrocnemius, a predominantly glycolytic SM, the NBR absence promotes changes that favor mitochondrial oxidative phosphorylation capacity. In addition, in L6 myocytes, NB treatment (5 µg/mL/16 h) promoted lower O2 consumption coupled to ATP synthesis, suggesting direct action at SM cells. Altogether, the study reinforces the hypothesis that inhibition of NB-NBR signaling enhances the capacity for oxidative phosphorylation of white SM, encouraging future studies to elucidate their contribution on other types of SM and whole body energy expenditure, which may lead to a new target to drug development for obesity treatment.NEW & NOTEWORTHY This study describes neuromedin B (NB) and NB receptor as new regulators of skeletal muscle mitochondrial function. The white skeletal muscle mitochondrial oxidative phosphorylation capacity was increased by NB receptor genetic disruption in female mice. These findings may contribute to the resistance to diet-induced obesity, previously found in these mice, which requires future studies. Thus, investigations are necessary to clarify if blockade of NB receptor may be an approach to develop drugs to combat obesity.
Assuntos
Fosforilação Oxidativa , Receptores da Bombesina , Trifosfato de Adenosina/metabolismo , Animais , Feminino , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Obesidade/metabolismo , RNA Mensageiro/metabolismo , Receptores da Bombesina/genética , Receptores da Bombesina/metabolismoRESUMO
BACKGROUND: G protein coupled receptor kinase 2 (GRK2) has been demonstrated to play a crucial role in the development of chronic pain. Acupuncture is an alternative therapy widely used for pain management. In this study, we investigated the role of spinal neuronal GRK2 in electroacupuncture (EA) analgesia. METHODS: The mice model of inflammatory pain was built by subcutaneous injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the hind paws. The mechanical allodynia of mice was examined by von Frey test. The mice were subjected to EA treatment (BL60 and ST36 acupuncture points) for 1 week. Overexpression and down-regulation of spinal neuronal GRK2 were achieved by intraspinal injection of adeno associated virus (AAV) containing neuron-specific promoters, and microglial activation and neuroinflammation were evaluated by real-time PCR. RESULTS: Intraplantar injection with CFA in mice induced the decrease of GRK2 and microglial activation along with neuroinflammation in spinal cord. EA treatment increased the spinal GRK2, reduced neuroinflammation, and significantly decreased CFA-induced mechanical allodynia. The effects of EA were markedly weakened by non-cell-specific downregulation of spinal GRK2. Further, intraspinal injection of AAV containing neuron-specific promoters specifically downregulated neuronal GRK2, and weakened the regulatory effect of EA on CFA-induced mechanical allodynia and microglial activation. Meanwhile, overexpression of spinal neuronal GRK2 decreased mechanical allodynia. All these indicated that the neuronal GRK2 mediated microglial activation and neuroinflammation, and subsequently contributed to CFA-induced inflammatory pain. CONCLUSION: The restoration of the spinal GRK2 and subsequent suppression of microglial activation and neuroinflammation might be an important mechanism for EA analgesia. Our findings further suggested that the spinal GRK2, especially neuronal GRK2, might be the potential target for EA analgesia and pain management, and we provided a new experimental basis for the EA treatment of pain.
Assuntos
Animais , Camundongos , Eletroacupuntura , Microglia/fisiologia , Quinase 2 de Receptor Acoplado a Proteína G/fisiologia , Manejo da Dor , Dor/induzido quimicamente , Inflamação/induzido quimicamente , Inflamação/terapia , NeurôniosRESUMO
Renal vascular reactivity to vasoconstrictors is preserved in sepsis in opposition to what happens in the systemic circulation. We studied whether this distinct behavior was related to α1 adrenergic receptor density, G protein-coupled receptor kinase 2 (GRK2) and the putative role of nitric oxide (NO). Sepsis was induced in female mice by cecal ligation and puncture (CLP). Wildtype mice were treated with prazosin 12 h after CLP or nitric oxide synthase 2 (NOS-2) inhibitor, 30 min before and 6 and 12 h after CLP. In vivo experiments and biochemistry assays were performed 24 h after CLP. Sepsis decreased the systemic mean arterial pressure (MAP) and the vascular reactivity to phenylephrine. Sepsis also reduced basal renal blood flow which was normalized by treatment with prazosin. Sepsis led to a substantial decrease in GRK2 level associated with an increase in α1 adrenergic receptor density in the kidney. The disappearance of renal GRK2 was prevented in NOS-2-KO mice or mice treated with 1400 W. Treatment of non-septic mice with an NO donor reduced GRK2 content in the kidney. Therefore, our results show that an NO-dependent reduction in GRK2 level in the kidney leads to the maintenance of a normal α1 adrenergic receptor density. The preservation of the density and/or functionality of this receptor in the kidney together with a higher vasoconstrictor tonus in sepsis lead to vasoconstriction. Thus, the increased concentration of vasoconstrictor mediators together with the preservation (and even increase) of the response to them may help to explain sepsis-induced acute kidney injury.
Assuntos
Injúria Renal Aguda/etiologia , Quinase 2 de Receptor Acoplado a Proteína G/metabolismo , Rim/metabolismo , Sepse/complicações , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/patologia , Injúria Renal Aguda/fisiopatologia , Animais , Pressão Arterial , Modelos Animais de Doenças , Feminino , Rim/patologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Miocárdio/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Circulação Renal , Sepse/metabolismo , Sepse/fisiopatologia , Fatores de TempoRESUMO
Megalin-mediated albumin endocytosis plays a critical role in albumin reabsorption in proximal tubule (PT) epithelial cells (PTECs). Some studies have pointed out the modulatory effect of bradykinin (BK) on urinary protein excretion, but its role in PT protein endocytosis has not yet been determined. Here, we studied the possible correlation between BK and albumin endocytosis in PT. Using LLC-PK1 cells, a model of PTECs, we showed that BK specifically inhibited megalin-mediated albumin endocytosis. This inhibitory effect of BK was mediated by B2 receptor (B2R) because it was abolished by HOE140, an antagonist of B2R, but it was not affected by Lys-des-Arg9-BK, an antagonist of B1. BK induced the stall of megalin in EEA1+ endosomes, but not in LAMP1+ lysosomes, leading to a decrease in surface megalin expression. In addition, we showed that BK, through B2R, activated calphostin C-sensitive protein kinase C, which mediated its effect on the surface megalin expression and albumin endocytosis. These results reveal an important modulatory mechanism of PT albumin endocytosis by BK, which opens new possibilities to understanding the effect of BK on urinary albumin excretion.
Assuntos
Albuminas/metabolismo , Bradicinina/farmacologia , Endocitose/efeitos dos fármacos , Túbulos Renais Proximais/efeitos dos fármacos , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Animais , Linhagem Celular , Ativação Enzimática , Túbulos Renais Proximais/metabolismo , Células LLC-PK1 , Proteína Quinase C/metabolismo , Receptor B2 da Bradicinina/metabolismo , SuínosRESUMO
Cutaneous mast cells (MCs) express Mas-related G protein-coupled receptor-X2 (MRGPRX2; mouse ortholog MrgprB2), which is activated by an ever-increasing number of cationic ligands. Antimicrobial host defense peptides (HDPs) generated by keratinocytes contribute to host defense likely by 2 mechanisms, one involving direct killing of microbes and the other via MC activation through MRGPRX2. However, its inappropriate activation may cause pseudoallergy and likely contribute to the pathogenesis of rosacea, atopic dermatitis, allergic contact dermatitis, urticaria, and mastocytosis. Gain- and loss-of-function missense single nucleotide polymorphisms in MRGPRX2 have been identified. The ability of certain ligands to serve as balanced or G protein-biased agonists has been defined. Small-molecule HDP mimetics that display both direct antimicrobial activity and activate MCs via MRGPRX2 have been developed. In addition, antibodies and reagents that modulate MRGPRX2 expression and signaling have been generated. In this article, we provide a comprehensive update on MrgprB2 and MRGPRX2 biology. We propose that harnessing MRGPRX2's host defense function by small-molecule HDP mimetics may provide a novel approach for the treatment of antibiotic-resistant cutaneous infections. In contrast, MRGPRX2-specific antibodies and inhibitors could be used for the modulation of allergic and inflammatory diseases that are mediated via this receptor.
Assuntos
Mastócitos/imunologia , Mutação de Sentido Incorreto , Proteínas do Tecido Nervoso/imunologia , Polimorfismo de Nucleotídeo Único , Receptores Acoplados a Proteínas G/imunologia , Receptores de Neuropeptídeos/imunologia , Dermatopatias , Pele/imunologia , Animais , Anti-Infecciosos/uso terapêutico , Materiais Biomiméticos/uso terapêutico , Humanos , Mastócitos/patologia , Camundongos , Proteínas do Tecido Nervoso/genética , Receptores Acoplados a Proteínas G/genética , Receptores de Neuropeptídeos/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Pele/patologia , Dermatopatias/tratamento farmacológico , Dermatopatias/genética , Dermatopatias/imunologia , Dermatopatias/patologiaRESUMO
Previously we have reported that the G protein-coupled receptor (GPCR)-like PfSR25 in Plasmodium falciparum is a potassium (K+) sensor linked to intracellular calcium signaling and that knockout parasites (PfSR25-) are more susceptible to oxidative stress and antimalarial compounds. Here, we explore the potential role of PfSR25 in susceptibility to the antimalarial compounds atovaquone, chloroquine, dihydroartemisinin, lumefantrine, mefloquine, piperaquine, primaquine, and pyrimethamine and the Medicine for Malaria Venture (MMV) compounds previously described to act on egress/invasion (MMV006429, MMV396715, MMV019127, MMV665874, MMV665878, MMV665785, and MMV66583) through comparative assays with PfSR25- and 3D7 parasite strains, using flow cytometry assays. The IC50 and IC90 results show that lumefantrine and piperaquine have greater activity on the PfSR25- parasite strain when compared to 3D7. For MMV compounds, we found no differences between the strains except for the compound MMV665831, which we used to investigate the store-operated calcium entry (SOCE) mechanism. The results suggest that PfSR25 may be involved in the mechanism of action of the antimalarials lumefantrine and piperaquine. Our data clearly show that MMV665831 does not affect calcium entry in parasites after we depleted their internal calcium pools with thapsigargin. The results demonstrated here shed light on new possibilities on the antimalarial mechanism, bringing evidence of the involvement of the GPCR-like PfSR25.
RESUMO
OBJECTIVE: This review aims to study the receptor's family and functions most related to COVID-19 infection and also suggest the tissue and cell location on which the majority of COVID-19 receptors are mainly expressed. METHODS: This systematic review is according to PRISMA guidelines. PubMed, Cochrane, SciELO, Lilacs, Web of Science, and DOAJ databases were used. Clinical trials and research articles studying receptors related to COVID-19 were included in this review. R programming language was used to elaborate charts and receptors network, and SPSS(26v) software was used to perform statistical analysis (PROSPERO: CRD42020210643). RESULTS: The majority of studies on the involvement of receptors in COVID-19 included plasma receptors and G protein-coupled receptor families (p<0.05). These receptors are highly expressed in the brain (24%) and 80% of them can interact with each other in a protein network, exerting some regulatory effects on various tissues. The main influential receptor in the network of receptors involved in the COVID-19 was the EGFR and the majority of receptors were associated with pathological processes of the disease (p<0.05), including the amplification of inflammatory responses in COVID-19, which may be related to neurological disorders in some cases. Studies on receptors involved in the COVID-19 included mainly patients from the United States, Spain, and Brazil (p<0.05). CONCLUSION: Plasma receptors and G protein-coupled receptors, especially the EGFR, involved in pathological effects of the COVID-19 inflammatory process in the brain have shown significant importance in this review.
Assuntos
COVID-19 , Doenças do Sistema Nervoso , Receptores Acoplados a Proteínas G , Receptores Virais , Encéfalo , Humanos , Doenças do Sistema Nervoso/virologiaRESUMO
INTRODUCTION: In light of the current COVID-19 pandemic, during which the world is confronted with a new, highly contagious virus that suppresses innate immunity as one of its initial virulence mechanisms, thus escaping from first-line human defense mechanisms, enhancing innate immunity seems a good preventive strategy. METHODS: Without the intention to write an official systematic review, but more to give an overview of possible strategies, in this review article we discuss several interventions that might stimulate innate immunity and thus our defense against (viral) respiratory tract infections. Some of these interventions can also stimulate the adaptive T- and B-cell responses, but our main focus is on the innate part of immunity. We divide the reviewed interventions into: 1) lifestyle related (exercise, >7 h sleep, forest walking, meditation/mindfulness, vitamin supplementation); 2) Non-specific immune stimulants (letting fever advance, bacterial vaccines, probiotics, dialyzable leukocyte extract, pidotimod), and 3) specific vaccines with heterologous effect (BCG vaccine, mumps-measles-rubeola vaccine, etc). RESULTS: For each of these interventions we briefly comment on their definition, possible mechanisms and evidence of clinical efficacy or lack of it, especially focusing on respiratory tract infections, viral infections, and eventually a reduced mortality in severe respiratory infections in the intensive care unit. At the end, a summary table demonstrates the best trials supporting (or not) clinical evidence. CONCLUSION: Several interventions have some degree of evidence for enhancing the innate immune response and thus conveying possible benefit, but specific trials in COVID-19 should be conducted to support solid recommendations.