RESUMO
Cetaceans represent a natural experiment within the tree of life in which a lineage changed from terrestrial to aquatic habitats. This shift involved phenotypic modifications, representing an opportunity to explore the genetic bases of phenotypic diversity. Among the different molecular systems that maintain cellular homeostasis, ion channels are crucial for the proper physiological functioning of all living species. This study aims to explore the evolution of ion channels during the evolutionary history of cetaceans. To do so, we created a bioinformatic pipeline to annotate the repertoire of ion channels in the genome of the species included in our sampling. Our main results show that cetaceans have, on average, fewer protein-coding genes and a higher percentage of annotated ion channels than non-cetacean mammals. Signals of positive selection were detected in ion channels related to the heart, locomotion, visual and neurological phenotypes. Interestingly, we predict that the NaV1.5 ion channel of most toothed whales (odontocetes) is sensitive to tetrodotoxin, similar to NaV1.7, given the presence of tyrosine instead of cysteine, in a specific position of the ion channel. Finally, the gene turnover rate of the cetacean crown group is more than three times faster than that of non-cetacean mammals.
Assuntos
Cetáceos , Evolução Molecular , Canais Iônicos , Animais , Cetáceos/genética , Cetáceos/fisiologia , Canais Iônicos/genética , Canais Iônicos/metabolismo , Filogenia , Biologia Computacional/métodos , GenomaRESUMO
Objective: To evaluate the expression of UCP1, UCP2, and UCP3 mRNA and encoded proteins in epicardial and mediastinal adipose tissues in patients with coronary artery disease (CAD). Subjects and methods: We studied 60 patients with CAD and 106 patients undergoing valve replacement surgery (controls). Expression levels of UCP1, UCP2, and UCP3 mRNA and encoded proteins were measured by quantitative real-time PCR and Western blot analysis, respectively. Results: : We found increased UCP1, UCP2, and UCP3 mRNA levels in the epicardial adipose tissue in the CAD versus the control group, and higher UCP1 and UCP3 mRNA expression in the epicardial compared with the mediastinal tissue in the CAD group. There was also increased expression of UCP1 protein in the epicardial tissue and UCP2 protein in the mediastinum tissue in patients with CAD. Finally, UCP1 expression was associated with levels of fasting plasma glucose, and UCP3 expression was associated with levels of high-density lipoprotein cholesterol and low-density cholesterol in the epicardial tissue. Conclusion: Our study supports the hypothesis that higher mRNA expression by UCP genes in the epicardial adipose tissue could be a protective mechanism against the production of reactive oxygen species and may guard the myocardium against damage. Thus, UCP levels are essential to maintain the adaptive phase of cardiac injury in the presence of metabolic disorders.
Assuntos
Doença da Artéria Coronariana , Mediastino , Humanos , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Doença da Artéria Coronariana/genética , Canais Iônicos/genética , Canais Iônicos/metabolismo , Tecido Adiposo Marrom/química , Tecido Adiposo Marrom/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Tecido Adiposo/metabolismo , Colesterol , Proteína Desacopladora 3/genética , Proteína Desacopladora 3/metabolismo , Músculo Esquelético , Proteína Desacopladora 2/genética , Proteína Desacopladora 2/metabolismoRESUMO
Myeloid-derived suppressor cells (MDSC) are a heterogeneous cell population with high immunosuppressive activity that proliferates in infections, inflammation, and tumor microenvironments. In tumors, MDSC exert immunosuppression mainly by producing reactive oxygen species (ROS), a process triggered by the NADPH oxidase 2 (NOX2) activity. NOX2 is functionally coupled with the Hv1 proton channel in certain immune cells to support sustained free-radical production. However, a functional expression of the Hv1 channel in MDSC has not yet been reported. Here, we demonstrate that mouse MDSC express functional Hv1 proton channel by immunofluorescence microscopy, flow cytometry, and Western blot, besides performing a biophysical characterization of its macroscopic currents via patch-clamp technique. Our results show that the immunosuppression by MDSC is conditional to their ability to decrease the proton concentration elevated by the NOX2 activity, rendering Hv1 a potential drug target for cancer treatment.
Assuntos
Canais Iônicos , Células Supressoras Mieloides , Prótons , Linfócitos T , Animais , Canais Iônicos/genética , Canais Iônicos/metabolismo , Camundongos , Células Supressoras Mieloides/imunologia , NADPH Oxidase 2/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Linfócitos T/imunologiaRESUMO
Neuropathic pain is one of the primary forms of chronic pain and is the consequence of the somatosensory system's direct injury or disease. It is a relevant public health problem that affects about 10% of the world's general population. In neuropathic pain, alteration in neurotransmission occurs at various levels, including the dorsal root ganglia, the spinal cord, and the brain, resulting from the malfunction of diverse molecules such as receptors, ion channels, and elements of specific intracellular signaling pathways. In this context, there have been exciting advances in elucidating neuropathic pain's cellular and molecular mechanisms in the last decade, including the possible role that long non-coding RNAs (lncRNAs) may play, which open up new alternatives for the development of diagnostic and therapeutic strategies for this condition. This review focuses on recent studies associated with the possible relevance of lncRNAs in the development and maintenance of neuropathic pain through their actions on the functional expression of ion channels. Recognizing the changes in the function and spatio-temporal patterns of expression of these membrane proteins is crucial to understanding the control of neuronal excitability in chronic pain syndromes.
Assuntos
Dor Crônica , Neuralgia , RNA Longo não Codificante , Animais , Dor Crônica/genética , Modelos Animais de Doenças , Gânglios Espinais/metabolismo , Humanos , Canais Iônicos/genética , Canais Iônicos/metabolismo , Neuralgia/genética , Neuralgia/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismoRESUMO
Voltage-dependent proton-permeable channels are membrane proteins mediating a number of important physiological functions. Here we report the presence of a gene encoding Hv1 voltage-dependent, proton-permeable channels in two species of reef-building corals. We performed a characterization of their biophysical properties and found that these channels are fast-activating and modulated by the pH gradient in a distinct manner. The biophysical properties of these novel channels make them interesting model systems. We have also developed an allosteric gating model that provides mechanistic insight into the modulation of voltage-dependence by protons. This work also represents the first functional characterization of any ion channel in scleractinian corals. We discuss the implications of the presence of these channels in the membranes of coral cells in the calcification and pH-regulation processes and possible consequences of ocean acidification related to the function of these channels.
Assuntos
Antozoários/metabolismo , Canais Iônicos/metabolismo , Prótons , Animais , Recifes de Corais , Concentração de Íons de Hidrogênio , Canais Iônicos/genética , Água do Mar/químicaRESUMO
Pannexin1 (Panx1) channels are ubiquitously expressed in vertebrate cells and are widely accepted as adenosine triphosphate (ATP)-releasing membrane channels. Activation of Panx1 has been associated with phosphorylation in a specific tyrosine residue or cleavage of its C-terminal domains. In the present work, we identified a residue (S394) as a putative phosphorylation site by Ca2+/calmodulin-dependent kinase II (CaMKII). In HeLa cells transfected with rat Panx1 (rPanx1), membrane stretch (MS)-induced activation-measured by changes in DAPI uptake rate-was drastically reduced by either knockdown of Piezo1 or pharmacological inhibition of calmodulin or CaMKII. By site-directed mutagenesis we generated rPanx1S394A-EGFP (enhanced green fluorescent protein), which lost its sensitivity to MS, and rPanx1S394D-EGFP, mimicking phosphorylation, which shows high DAPI uptake rate without MS stimulation or cleavage of the C terminus. Using whole-cell patch-clamp and outside-out excised patch configurations, we found that rPanx1-EGFP and rPanx1S394D-EGFP channels showed current at all voltages between ±100 mV, similar single channel currents with outward rectification, and unitary conductance (â¼30 to 70 pS). However, using cell-attached configuration we found that rPanx1S394D-EGFP channels show increased spontaneous unitary events independent of MS stimulation. In silico studies revealed that phosphorylation of S394 caused conformational changes in the selectivity filter and increased the average volume of lateral tunnels, allowing ATP to be released via these conduits and DAPI uptake directly from the channel mouth to the cytoplasmic space. These results could explain one possible mechanism for activation of rPanx1 upon increase in cytoplasmic Ca2+ signal elicited by diverse physiological conditions in which the C-terminal domain is not cleaved.
Assuntos
Sinalização do Cálcio , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Conexinas/química , Conexinas/metabolismo , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/metabolismo , Cálcio/metabolismo , Calmodulina/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Conexinas/genética , Citoplasma/metabolismo , Proteínas de Fluorescência Verde/genética , Células HeLa , Humanos , Indóis/farmacocinética , Canais Iônicos/genética , Canais Iônicos/metabolismo , Simulação de Dinâmica Molecular , Proteínas do Tecido Nervoso/genética , Técnicas de Patch-Clamp , Fosforilação , Serina/genética , Serina/metabolismoRESUMO
The dissipation of acute acid loads by the voltage-gated proton channel (Hv1) relies on regulating the channel's open probability by the voltage and the ΔpH across the membrane (ΔpH = pHex - pHin). Using monomeric Ciona-Hv1, we asked whether ΔpH-dependent gating is produced during the voltage sensor activation or permeation pathway opening. A leftward shift of the conductance-voltage (G-V) curve was produced at higher ΔpH values in the monomeric channel. Next, we measured the voltage sensor pH dependence in the absence of a functional permeation pathway by recording gating currents in the monomeric nonconducting D160N mutant. Increasing the ΔpH leftward shifted the gating charge-voltage (Q-V) curve, demonstrating that the ΔpH-dependent gating in Hv1 arises by modulating its voltage sensor. We fitted our data to a model that explicitly supposes the Hv1 voltage sensor free energy is a function of both the proton chemical and the electrical potential. The parameters obtained showed that around 60% of the free energy stored in the ΔpH is coupled to the Hv1 voltage sensor activation. Our results suggest that the molecular mechanism underlying the Hv1 ΔpH dependence is produced by protons, which alter the free-energy landscape around the voltage sensor domain. We propose that this alteration is produced by accessibility changes of the protons in the Hv1 voltage sensor during activation.
Assuntos
Algoritmos , Ativação do Canal Iônico/fisiologia , Canais Iônicos/fisiologia , Modelos Biológicos , Prótons , Sequência de Aminoácidos , Animais , Feminino , Humanos , Concentração de Íons de Hidrogênio , Ativação do Canal Iônico/genética , Canais Iônicos/genética , Canais Iônicos/metabolismo , Potenciais da Membrana/fisiologia , Camundongos , Simulação de Dinâmica Molecular , Mutação , Oócitos/metabolismo , Oócitos/fisiologia , Homologia de Sequência de Aminoácidos , Xenopus laevisRESUMO
BACKGROUND: Uncoupling protein 2 (UCP2) plays an important role in energy expenditure regulation. Previous studies have associated the common -866G/A (rs659366) and Ins/Del polymorphisms in the UCP2 gene with metabolic and obesity-related phenotypes. However, it is still unclear whether these polymorphisms influence weight loss after bariatric surgery. OBJECTIVES: To investigate whether UCP2 -866G/A and Ins/Del polymorphisms are associated with weight loss outcomes after bariatric surgery. SETTING: Longitudinal study in a university hospital. METHODS: We retrospectively evaluated 186 patients who underwent Roux-en-Y gastric bypass (RYGB) surgery for clinical and laboratory characteristics in the preoperative period, 6, 12, and 18 months after RYGB. The -866G/A (rs659366) polymorphism was genotyped using real-time PCR, while the Ins/Del polymorphism was genotyped by direct separation of PCR products in 2.5% agarose gels. RESULTS: Patients with the -866A/A genotype showed higher body mass index (BMI) after 6, 12, and 18 months of surgery and excess body weight after 6 and 12 months compared with G/G patients. They also showed lower excess weight loss (EWL%) after 6 and 12 months of surgery. Ins allele carriers (Ins/Ins + Ins/Del) had lower delta (Δ) BMI 12 months after surgery compared with Del/Del patients. Accordingly, patients carrying haplotypes with ≥2 risk alleles of these polymorphisms had higher BMI and excess weight and lower EWL% during follow-up. CONCLUSION: UCP2 -866A/A genotype is associated with higher BMI and excess weight and lower EWL% during an 18-month follow-up of patients who underwent RYGB, while the Ins allele seems to be associated with lower ΔBMI 12 months after surgery. Further studies are needed to confirm the associations of the -866G/A and Ins/Del polymorphisms with weight loss after bariatric surgery.
Assuntos
Derivação Gástrica , Obesidade Mórbida , Índice de Massa Corporal , Humanos , Canais Iônicos/genética , Estudos Longitudinais , Proteínas Mitocondriais/genética , Obesidade Mórbida/genética , Obesidade Mórbida/cirurgia , Estudos Retrospectivos , Proteína Desacopladora 2/genética , Redução de Peso/genéticaRESUMO
NALCN encodes a sodium ion leak channel expressed in the nervous system that conducts a persistent influx of sodium ions to facilitate action potential formation. Homozygous or compound heterozygous loss of function variants in NALCN cause infantile hypotonia with psychomotor retardation and characteristic facies-1 (IHPRF1; OMIM 615419). Through exome and Sanger sequencing, we found two siblings of Afro-Caribbean ancestry who are homozygous for a known NALCN pathogenic variant, p.Arg735Ter, leading to failure to thrive, severe hypotonia, and dolichocephaly. The older sibling died suddenly without a known etiology after evaluation but before molecular diagnosis. An international collaboration originating from a resource limited Caribbean island facilitated molecular diagnosis. Due to its small population, geographical isolation, and low socioeconomic status, the island lacks many specialty medical services, including clinical genetics. Descriptions of genetic disorders affecting individuals of Afro-Caribbean ancestry are rarely reported in the medical literature. Diagnosis of IHPRF1 is important, as individuals with biallelic pathogenic NALCN variants are severely affected and potentially are at risk for cardiorespiratory arrest. Additionally, knowing the pathogenic variants allows the possibility of prenatal or preimplantation genetic diagnosis.
Assuntos
Predisposição Genética para Doença , Canais Iônicos/genética , Proteínas de Membrana/genética , Hipotonia Muscular/genética , Transtornos Psicomotores/genética , Região do Caribe , Exoma/genética , Feminino , Homozigoto , Humanos , Lactente , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Deficiência Intelectual/patologia , Masculino , Hipotonia Muscular/diagnóstico , Hipotonia Muscular/patologia , Mutação de Sentido Incorreto/genética , Transtornos Psicomotores/diagnóstico , Transtornos Psicomotores/patologia , IrmãosRESUMO
BACKGROUND: Bariatric surgery is currently the most effective treatment for patients with severe obesity. Uncoupling proteins (UCP) 1, 2, and 3 play key roles in the regulation of energy balance and weight. Previous studies have suggested that changes in UCP1-3 genes could influence weight loss after bariatric surgery. However, it is still unclear if these UCPs are indeed involved in weight loss variability after surgery. Therefore, we performed a systematic review aiming to summarize the results of studies on this subject. METHODS: A literature search was performed for all studies that evaluated associations of UCP1-3 expressions and their polymorphisms with obesity-related outcomes after bariatric surgery. RESULTS: Twenty-six studies were eligible for inclusion in this systematic review. Among them, 18 evaluated UCP1-3 expressions while 8 studies investigated the association between UCP1-3 polymorphisms and weight loss after bariatric surgery. In general, UCP2 and UCP3 expressions in adipose tissue and skeletal muscle seem to be affected by metabolic changes of bariatric surgery, which might be influenced by the surgery type. Data on UCP1 expression in adipose tissue is still inconclusive. Only few studies investigated the association between polymorphisms in UCP1-3 genes and weight loss after bariatric surgery, with contradictory results. CONCLUSION: Available studies suggest that changes caused by bariatric surgery could influence UCP2 and UCP3 expressions in adipose tissue and muscles, consequently affecting weight loss. However, because of the reduced number of studies, further studies are needed to confirm whether these UCPs and their polymorphisms are indeed involved in weight loss after bariatric surgery.