The influence of Na,K-ATPase isoforms in ouabain signaling cascade against LPS induced NF-kB activation in glial cells.

Na,K-ATPase é uma proteína de membrana que tem como função manter o equilíbrio osmótico nas células pela hidrólise de ATP. A ouabaína (OUA) se liga a Na,K-ATPase e é capaz de ativar cascatas de sinalização. As subunidades a da Na,K-ATPase possuem 4 isoformas que são distribuídas de forma diferenciada nos tecidos. As células da glia são importantes na resposta contra lesões no cérebro e também controlam a inflamação. Dados na literatura mostram que a OUA tem efeito protetor em alguns tipos de dano. O objetivo do estudo é avaliar a função da isoforma a2 na cultura de células da glia em resposta à OUA e ao LPS. Nós investigamos a ação da OUA em diversas concentrações e LPS (1g/mL) na viabilidade celular (LDH) e proliferação celular (MTT). O LPS foi utilizado como modelo de inflamação e uma das perguntas era se o tratamento prévio com OUA, seria capaz de reverter a ativação do fator de transcrição NF-kB que está envolvido com inflamação. O pré-tratamento com OUA diminuiu a ativação do NF-kB induzida pelo LPS. Após, nós silenciamos a isoforma a2 das células da glia com RNAi. Os nossos dados mostram que o pré-tratamento com OUA reverte o efeito na ativação do NF-kB causado pelo LPS. Provavelmente, a isoforma a2 está relacionada com alguma via de sinalização que interage com a via do LPS.Na,K-ATPase is a conserved membrane protein which maintains the osmotic balance in the cell by the hydrolysis of ATP. Ouabain (OUA) binds to Na,K-ATPase and it can activate signaling pathways. The a subunits of Na,K-ATPase have 4 isoforms which are distributed in a different pattern in the tissues. Glial cells have an important role in the response against injury and they also control inflammation. Some data have reported that OUA can protect against some types of injury. The aim of this study is to evaluate the role of a2 isoform in glial cells in response to OUA and LPS stimulus. We investigated the action of OUA and LPS in cell viability (LDH) and cell proliferation (MTT). LPS was used as a model of inflammation and one of our questions was if the treatment with OUA before LPS was capable of reduce the activation of the transcription factor NF-kB which is involved in inflammation. The pre-treatment with OUA decreased the NF-kB activation induced by LPS. We also silenced the a2 isoform in culture glial cells with iRNA. Taken together our data showed that OUA pretreatment reversed the NF-kB activation induced by LPS in primary cultures of glial cells from mice. Probably,the a2 isoform is related with some signaling pathway that interacts with the LPS pathway

TNFR1 role in ouabain effects in inflammatory pathway in mice hippocampus.

O efeito anti-inflamatório da ouabaína tem sido demonstrado no sistema nervoso central. Baixas doses de ouabaína se ligam à Na+,K+-ATPase e ativam vias de sinalização relacionadas a crescimento, apoptose e inflamação. Nosso grupo mostrou que a ouabaína modula a expressão de BDNF, TNF e IL-1b. TNF tem um papel importante na inflamação e possui uma resposta complexa; e pode ser encontrado em duas formas: TNFtm (transmembrana) e TNFsol (solúvel). TNFsol é resultante da clivagem de TNFtm pela enzima TACE/ADAM 17. As duas formas de TNF interagem de forma diferente com os receptores de TNF: TNFR1 e TNFR2. TNFR1 possui um domínio de morte e é relacionado à via clássica de TNF com um perfil pró-inflamatório e pró-apoptótico. O objetivo do presente trabalho foi elucidar o papel do TNFR1 frente a estímulos com ouabaína e LPS. Foram utilizados camundongos TNFR1 KO para estudar o receptor. Os animais foram tratados com ouabaína ou salina seguido de uma segunda injeção de LPS ou salina. Depois de 2 horas da segunda injeção, hipocampo e córtex foram dissecados para os ensaios bioquímicos. Para os testes de comportamento, os animais foram avaliados no teste de campo aberto 1 dia após o tratamento; e no ensaio de esquiva inibitória 3 dias após o desafio. Os resultados mostraram que o LPS aumenta os níveis de TNF no soro dos animais WT e TNFR1 KO, mas a quantidade de TNF liberado no animal TNFR1 KO era superior ao no animal WT. A liberação de TNF é aumentada e a expressão de TNFR2 é diminuída no hipocampo somente nos animais TNFR1 KO tratados com LPS. IL-1b é aumentado apenas no grupo WT tratado com LPS, mostrando que o TNFR1 modula a expressão de IL-1b no hipocampo. O BDNF é aumentado no grupo TNFR1 KO tratado com LPS, mas ao mesmo tempo, a expressão de TrkB não é modulada pelo LPS como no grupo WT. Isto causa mudanças importantes no comportamento como os animais TNFR1 KO tratados com LPS apresentam diminuição na velocidade média e no tempo no centro. Estes dados demonstram que a resposta ao tratamento com LPS é mais severa nestes animais, refletindo maior comportamento ansioso. A ouabaína também aumenta a distância percorrida durante todos os experimentos nos animais WT, o que não foi encontrado nos animais TNFR1 KO, mostrando que o aumento de locomoção e exploração são dependentes de TNFR1. No ensaio de esquiva inibitória, o tratamento com ouabaína no grupo WT levou a um aumento no tempo de latência no dia 2, enquanto que no grupo TNFR1 KO este efeito foi perdido. Entretanto, nos animais TNFR1 KO, houve um aumento no tempo de latência no dia 2 no grupo controle e ouabaína+LPS, mostrando que a ouabaína de alguma forma depende de vias inflamatórias para ser protetora. Logo, nosso estudo mostrou a relevância da sinalização do TNFR1 no hipocampo e como isso pode ser um alvo importante para a neuroinflamação.The anti-inflammatory role of ouabain in central nervous system has been demonstrated. Low doses of ouabain binds to Na+,K+-ATPase and activate signaling pathways related to growth, apoptosis and also inflammation. Our group has shown that ouabain modulates BDNF, TNF and IL-1b expression. TNF has a major role in inflammation and also has a very complex response. TNF can be found in two forms: tmTNF (transmembrane) and solTNF (soluble). SolTNF is a result of tmTNF cleavage by TACE/ADAM 17. Those two forms interact differently between the two TNF receptors: TNFR1 and TNFR2. TNFR1 has a death domain and is related to a canonical TNF pathway with a pro-inflammatory and pro-apoptotic profile. Thus, the objective of our work is to understand the role of TNFR1 in ouabain and as well as in LPS stimulus. To study the receptor, we used TNFR1 KO mice. The animals were treated with ouabain or saline followed by a second injection of LPS or saline. After 2 hours of the second injection, the hippocampus and cortex were dissected for the biochemical assays. For the behavior tests, the animals were evaluated in open field 24 hours after the treatment and after 3 days in passive avoidance. The results showed that LPS increased TNF levels in serum in WT and TNFR1 KO mice, but the amount of TNF released in TNFR1 KO mice was higher than in WT. TNF release was also increased and TNFR2 expression was decreased in hippocampus only in TNFR1 KO mice treated with LPS. IL-1b is increased only in WT group with LPS treatment showing that TNFR1 modulates IL-1b expression in hippocampus. BDNF is increased in TNFR1 KO group treated with LPS but at the same time, TrkB expression is not modulated by LPS as in WT group. This causes important modifications in behavior as TNFR1 KO mice presented in open field test a decrease in mean speed and in time in the center in LPS treated groups. These data demonstrate that LPS treatment is more severe in those animals and that also reflect in more anxious animals. Ouabain also increased distance travelled in the whole experiment in WT mice, which was not found in TNFR1 KO mice, demonstrating the increase in locomotion and exploration are TNFR1 dependent. In passive avoidance, ouabain in WT mice had a higher latency time in day 2 while in TNFR1 KO mice this effect was lost. However, in TNFR1 KO mice there was an increase in latency time in day 2 for control and ouabain+LPS groups showing that ouabain somehow needs inflammatory pathways to be protective. Thus, our study showed the relevance of TNFR1 signaling in the hippocampus and how this could be an important target for neuroprotection

Molecular Dysfunctions of Mitochondria-Associated Membranes (MAMs) in Alzheimer's Disease.

Alzheimer's disease (AD) is a multifactorial neurodegenerative pathology characterized by a progressive decline of cognitive functions. Alteration of various signaling cascades affecting distinct subcellular compartment functions and their communication likely contribute to AD progression. Among others, the alteration of the physical association between the endoplasmic reticulum (ER) and mitochondria, also reffered as mitochondria-associated membranes (MAMs), impacts various cellular housekeeping functions such as phospholipids-, glucose-, cholesterol-, and fatty-acid-metabolism, as well as calcium signaling, which are all altered in AD. Our review describes the physical and functional proteome crosstalk between the ER and mitochondria and highlights the contribution of distinct molecular components of MAMs to mitochondrial and ER dysfunctions in AD progression. We also discuss potential strategies targeting MAMs to improve mitochondria and ER functions in AD

The influence of Na+,K+-ATPase on glutamate signaling in neurodegenerative diseases and senescence

Decreased Na+,K+-ATPase (NKA) activity causes energy deficiency, which is commonly observed in neurodegenerative diseases. The NKA is constituted of three subunits: α, β and γ, with four distinct isoforms of the catalytic α subunit (α1-4). Genetic mutations in the ATP1A2 gene and ATP1A3 gene, encoding the α2 and α3 subunit isoforms, respectively can cause distinct neurological disorders, concurrent to impaired NKA activity. Within the central nervous system (CNS), the α2 isoform is expressed mostly in glial cells and the α3 isoform is neuron-specific. Mutations in ATP1A2 gene can result in familial hemiplegic migraine (FHM2), while mutations in the ATP1A3 gene can cause Rapid-onset dystonia-Parkinsonism (RDP) and alternating hemiplegia of childhood (AHC), as well as the cerebellar ataxia, areflexia, pescavus, optic atrophy and sensorineural hearing loss (CAPOS) syndrome. Data indicates that the central glutamatergic system is affected by mutations in the α2 isoform, however further investigations are required to establish a connection to mutations in the α3 isoform, especially given the diagnostic confusion and overlap with glutamate transporter disease. The age-related decline in brain α2/3 activity may arise from changes in the cyclic guanosine monophosphate (cGMP) and cGMP‐dependent protein kinase (PKG) pathway. Glutamate, through nitric oxide synthase (NOS), cGMP and PKG, stimulates brain α2/3 activity, with the glutamatergic N-methyl-D-aspartate (NMDA) receptor cascade able to drive an adaptive, neuroprotective response to inflammatory and challenging stimuli, including amyloid‐β. Here we review the NKA, both as an ion pump as well as a receptor that interacts with NMDA, including the role of NKA subunits mutations. Failure of the NKA-associated adaptive response mechanisms may render neurons more susceptible to degeneration over the course of aging

Consequences of the Lack of TNFR1 in Ouabain Response in the Hippocampus of C57BL/6J Mice

Ouabain is a cardiac glycoside that has a protective effect against neuroinflammation at low doses through Na+/K+-ATPase signaling and that can activate tumor necrosis factor (TNF) in the brain. TNF plays an essential role in neuroinflammation and regulates glutamate receptors by acting on two different receptors (tumor necrosis factor receptor 1 [TNFR1] and TNFR2) that have distinct functions and expression. The activation of constitutively and ubiquitously expressed TNFR1 leads to the expression of pro-inflammatory cytokines. Thus, this study aimed to elucidate the effects of ouabain in a TNFR1 knockout (KO) mouse model. Interestingly, the hippocampus of TNFR1 KO mice showed a basal increase in both TNFR2 membrane expression and brain-derived neurotrophic factor (BDNF) release, suggesting a compensatory mechanism. Moreover, ouabain activated TNF-α-converting enzyme/a disintegrin and metalloprotease 17 (TACE/ADAM17), decreased N-methyl-D-aspartate (NMDA) receptor subunit 2A (NR2A) expression, and induced anxiety-like behavior in both genotype animals, independent of the presence of TNFR1. However, ouabain induced an increase in interleukin (IL)-1β in the hippocampus, a decrease in IL-6 in serum, and an increase in NMDA receptor subunit 1 (NR1) only in wild-type (WT) mice, indicating that TNFR1 or TNFR2 expression may be important for some effects of ouabain. Collectively, our results indicate a connection between ouabain signaling and TNFR1, with the effect of ouabain partially dependent on TNFR1

Influence of N-methyl-D-aspartate receptors on ouabain activation of nuclear factor-kappa B in the rat hippocampus

It has been shown that ouabain (OUA) can activate the Na,K-ATPase complex and mediate intracellular signaling in the central nervous system (CNS). Inflammatory stimulus increases glutamatergic transmission, especially at N-methyl-D-aspartate (NMDA) receptors, which are usually coupled to the activation of nitric oxide synthase (NOS). Nuclear factor-kappa B (NF-kappa B) activation modulates the expression of genes involved in development, plasticity, and inflammation. The present work investigated the effects of OUA on NF-kappa B binding activity in rat hippocampus and the influence of this OUA-Na,K-ATPase signaling cascade in NMDA-mediated NF-kappa B activation. The findings presented here are the first report indicating that intrahippocampal administration of OUA, in a concentration that did not alter Na,K-ATPase or NOS activity, induced an activation of NF-kappa B, leading to increases in brain-derived neurotrophic factor (Bdnf), inducible NOS (iNos), tumor necrosis factor-alpha (Tnf-alpha), and B-cell leukemia/lymphoma 2 (Bcl2) mRNA levels. This response was not linked to any significant signs of neurodegeneration as showed via Fluoro-Jade B and Nissl stain. Intrahippocampal administration of NMDA induced NF alpha B activation and increased NOS and alpha 2/3-Na,K-ATPase activities. NMDA treatment further increased OUA-induced NF-kappa B activation, which was partially blocked by MK-801, an antagonist of NMDA receptor. These results suggest that OUA-induced NF-kappa B activation is at least in part dependent on Na,K-ATPase modulatory action of NMDA receptor in hippocampus. The interaction of these signaling pathways could be associated with biological mechanisms that may underlie the basal homeostatic state linked to the inflammatory signaling cascade in the brain. (c) 2011 Wiley Periodicals, Inc.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP [2003/08989-0]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq [485953-2007-2]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Universidade de Sao PauloUniversidade de Sao Paul

Accumulation of amyloid precursor protein C-terminal fragments triggers mitochondrial structure, function, and mitophagy defects in Alzheimer's disease models and human brains.

Several lines of recent evidence indicate that the amyloid precursor protein-derived C-terminal fragments (APP-CTFs) could correspond to an etiological trigger of Alzheimer's disease (AD) pathology. Altered mitochondrial homeostasis is considered an early event in AD development. However, the specific contribution of APP-CTFs to mitochondrial structure, function, and mitophagy defects remains to be established. Here, we demonstrate in neuroblastoma SH-SY5Y cells expressing either APP Swedish mutations, or the β-secretase-derived APP-CTF fragment (C99) combined with β- and γ-secretase inhibition, that APP-CTFs accumulation independently of Aβ triggers excessive mitochondrial morphology alteration (i.e., size alteration and cristae disorganization) associated with enhanced mitochondrial reactive oxygen species production. APP-CTFs accumulation also elicit basal mitophagy failure illustrated by enhanced conversion of LC3, accumulation of LC3-I and/or LC3-II, non-degradation of SQSTM1/p62, inconsistent Parkin and PINK1 recruitment to mitochondria, enhanced levels of membrane and matrix mitochondrial proteins, and deficient fusion of mitochondria with lysosomes. We confirm the contribution of APP-CTFs accumulation to morphological mitochondria alteration and impaired basal mitophagy in vivo in young 3xTgAD transgenic mice treated with γ-secretase inhibitor as well as in adeno-associated-virus-C99 injected mice. Comparison of aged 2xTgAD and 3xTgAD mice indicates that, besides APP-CTFs, an additional contribution of Aβ to late-stage mitophagy activation occurs. Importantly, we report on mitochondrial accumulation of APP-CTFs in human post-mortem sporadic AD brains correlating with mitophagy failure molecular signature. Since defective mitochondria homeostasis plays a pivotal role in AD pathogenesis, targeting mitochondrial dysfunctions and/or mitophagy by counteracting early APP-CTFs accumulation may represent relevant therapeutic interventions in AD

Linfoma cutâneo de células B: relato de caso Cutaneous B-cell lymphoma: a case report

Os linfomas cutâneos são classificados em linfomas de células B ou de células T, sendo os primeiros menos freqüentes. O linfoma cutâneo de células B (LCCB) pode ser primário ou secundário, tendo o último história natural mais agressiva, com pior prognóstico. Os autores apresentam um caso de LCCB secundário com três anos de evolução, curso indolente, sem envolvimento de outros órgãos além da pele, com ótima resposta ao tratamento quimioterápico. A distinção entre LCCB primário e secundário é muito difícil de ser realizada, uma vez que eles são clínica e histopatologicamente indistinguíveis. Deve-se sempre pesquisar o acometimento de órgãos internos para então definir o prognóstico.<br>Cutaneous lymphomas are classified as either type B cell or T cell lymphoma, the former type being less frequent. Cutaneous B cell lymphoma (CBCL) may be primary or secondary. The latter has a more aggressive natural history with a worse prognostic. In this paper, the authors present a secondary CBCL case with a three-year evolution, indolent course, without involvement of other organs beside the skin and with optimal response to chemotherapeutic treatment. The distinction between primary and secondary CBCL is very difficult to determine insofar as they are clinically and histopathologically indistinguishable. It is always necessary to investigate whether internal organs have been affected prior to defining the prognosis

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora