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The hippocampus is a brain region implicated in synaptic plasticity and memory formation; both processes require neuronal Ca

The expression of several hippocampal genes implicated in learning and memory processes requires that Ca(2+) signals generated in dendritic spines, dendrites, or the soma in response to neuronal stimulation reach the nucleus. The diffusion of Ca(2+) in the cytoplasm is highly restricted, so neurons must use other mechanisms to propagate Ca(2+) signals to the nucleus. Here, we present evidence showing that Ca(2+) release mediated by the ryanodine receptor (RyR) channel type-2 isoform (RyR2) contributes to the generation of nuclear Ca(2+) signals induced by gabazine (GBZ) addition, glutamate uncaging in the dendrites, or high-frequency field stimulation of primary hippocampal neurons. Additionally, GBZ treatment significantly increased cyclic adenosine monophosphate response element binding protein (CREB) phosphorylation—a key event in synaptic plasticity and hippocampal memory—and enhanced the expression of Neuronal Per Arnt Sim domain protein 4 (Npas4) and RyR2, two central regulators of these processes. Suppression of RyR-mediated Ca(2+) release with ryanodine significantly reduced the increase in CREB phosphorylation and the enhanced Npas4 and RyR2 expression induced by GBZ. We propose that RyR-mediated Ca(2+) release induced by neuronal activity, through its contribution to the sequential generation of nuclear Ca(2+) signals, CREB phosphorylation, Npas4, and RyR2 up-regulation, plays a central role in hippocampal synaptic plasticity and memory processes.

Neuronal Ca

Astaxanthin (ASX) is a carotenoid pigment with strong antioxidant properties. We have reported previously that ASX protects neurons from the noxious effects of amyloid-&beta, peptide oligomers, which promote excessive mitochondrial reactive oxygen species (mROS) production and induce a sustained increase in cytoplasmic Ca2+ concentration. These properties make ASX a promising therapeutic agent against pathological conditions that entail oxidative and Ca2+ dysregulation. Here, we studied whether ASX protects neurons from N-methyl-D-aspartate (NMDA)-induced excitotoxicity, a noxious process which decreases cellular viability, alters gene expression and promotes excessive mROS production. Incubation of the neuronal cell line SH-SY5Y with NMDA decreased cellular viability and increased mitochondrial superoxide production, pre-incubation with ASX prevented these effects. Additionally, incubation of SH-SY5Y cells with ASX effectively reduced the basal mROS production and prevented hydrogen peroxide-induced cell death. In primary hippocampal neurons, transfected with a genetically encoded cytoplasmic Ca2+ sensor, ASX also prevented the increase in intracellular Ca2+ concentration induced by NMDA. We suggest that, by preventing the noxious mROS and Ca2+ increases that occur under excitotoxic conditions, ASX could be useful as a therapeutic agent in neurodegenerative pathologies that involve alterations in Ca2+ homeostasis and ROS generation.

Aims: Previous studies indicate that hippocampal synaptic plasticity and spatial memory processes entail calcium release from intracellular stores mediated by ryanodine receptor (RyR) channels. In particular, RyR-mediated Ca2+ release is central for the dendritic spine remodeling induced by brain-derived neurotrophic factor (BDNF), a neurotrophin that stimulates complex signaling pathways leading to memory-associated protein synthesis and structural plasticity. To examine if upregulation of ryanodine receptor type-2 (RyR2) channels and the spine remodeling induced by BDNF entail reactive oxygen species (ROS) generation, and to test if RyR2 downregulation affects BDNF-induced spine remodeling and spatial memory. Results: Downregulation of RyR2 expression (short hairpin RNA [shRNA]) in primary hippocampal neurons, or inhibition of nitric oxide synthase (NOS) or NADPH oxidase, prevented agonist-mediated RyR-mediated Ca2+ release, whereas BDNF promoted cytoplasmic ROS generation. RyR2 downregulation ...

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) induces complex neuronal signaling cascades that are critical for the cellular changes underlying synaptic plasticity. These pathways include activation of Ca2+ entry via N-methyl-D-aspartate receptors and sequential activation of nitric oxide synthase and NADPH oxidase, which via generation of reactive nitrogen/oxygen species stimulate Ca2+-induced Ca2+ release mediated by Ryanodine Receptor (RyR) channels. These sequential events underlie BDNF-induced spine remodeling and type-2 RyR up-regulation. In addition, BDNF induces the nuclear translocation of the transcription factor Nrf2, a master regulator of antioxidant protein expression that protects cells against the oxidative damage caused by injury and inflammation. To investigate the possible BDNF-induced signaling cascades that mediate Nrf2 nuclear translocation in primary hippocampal cultures, we tested here whether reactive oxygen species, RyR-mediated Ca2+ release, ERK or PI3K contribute to this response. We found that pre-incubation of cultures with inhibitory ryanodine to suppress RyR-mediated Ca2+ release, with the reducing agent N-acetylcysteine or with inhibitors of ERK or PI3K activity, prevented the nuclear translocation of Nrf2 induced by incubation for 6 h with BFNF. Based on these combined results, we propose that the key role played by BDNF as an inducer of neuronal antioxidant responses, characterized by BDNF-induced Nfr2 nuclear translocation, entails crosstalk between reactive oxygen species and RyR-mediated Ca2+ release, and the participation of ERK and PI3K activities.

Introduction: Previous reports have proposed that Periodontal disease (PDis) predisposes to Alzheimer’s disease (AD), both highly prevalent pathologies among the elderly. The bacteria Aggregatibacter actinomycetemcomitans (Aa), associated with the most aggressive forms of PDis, are classified in different serotypes with distinct virulence according to the antigenicity of their lipopolysaccharide (LPS). Methods: Here, we determined the effects of purified LPS, from serotypes a, b or c of Aa, on primary cultures of microglia or mixed hippocampal cells. Results: We found that both culture types exhibited higher levels of inflammatory cytokines (IL-1β, IL-6 and TNFα) when treated with serotype b-LPS, compared with controls, as quantified by qPCR and/or ELISA. Also, cultures treated with serotype a-LPS displayed increased mRNA levels of the modulatory cytokines IL-4 and IL-10. Mixed hippocampal cultures treated with serotype b-LPS exhibited severe neuronal morphological changes and displayed increased levels of secreted Aβ1-42 peptide. These results indicate that LPS from different Aa serotypes triggers discriminatory immune responses, which differentially affect primary hippocampal cells. Conclusion: Altogether, our results show that treatment with serotype b-LPS triggers the secretion of proinflammatory cytokines by microglia, induces neurite shrinking, and increases the extracellular Aβ1-42 levels, all features strongly associated with the etiology of AD.

Neuronal Ca2+ signals are fundamental for synaptic transmission and activity-dependent changes in gene expression. Voltage-gated Ca2+ channels and N-methyl-d-aspartate receptors play major roles in mediating external Ca2+ entry during action potential firing and glutamatergic activity. Additionally, the inositol-1,4,5-trisphosphate receptor (IP3R) and the ryanodine receptor (RyR) channels expressed in the endoplasmic reticulum (ER) also contribute to the generation of Ca2+ signals in response to neuronal activity. The ER forms a network that pervades the entire neuronal volume, allowing intracellular Ca2+ release in dendrites, soma and presynaptic boutons. Despite its unique morphological features, the contributions of ER structure and of ER-shaping proteins such as atlastin - an ER enriched GTPase that mediates homotypic ER tubule fusion - to the generation of Ca2+ signals in dendrites remains unreported. Here, we investigated the contribution of RyR-mediated Ca2+ release to IP3-generated Ca2+ signals in dendrites of cultured hippocampal neurons. We also employed GTPase activity-deficient atlastin-2 (ATL2) mutants to evaluate the potential role of atlastin on Ca2+ signaling and ER-resident Ca2+ channel distribution. We found that pharmacological suppression of RyR channel activity increased the rising time and reduced the magnitude and propagation of IP3-induced Ca2+ signals. Additionally, ATL2 mutants induced specific ER morphological alterations, delayed the onset and increased the rising time of IP3-evoked Ca2+ signals, and caused RyR2 and IP3R1 aggregation and RyR2 redistribution. These results indicate that both RyR and ATL2 activity regulate IP3-induced Ca2+ signal dynamics through RyR-mediated Ca2+-induced Ca2+ release, ER shaping and RyR2 distribution.

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) induces complex neuronal signaling cascades that are critical for the cellular changes underlying synaptic plasticity. These pathways include activation of Ca

Background: RCM (reflectance confocal microscopy) is a noninvasive, high-resolution technology that has been proven to improve the diagnostic accuracy over clinical examination in several skin diseases. Objective: The aim of this article is to describe the morphologic features of halo nevi (HN) observed with RCM and correlate them with their dermoscopic characteristics. Method: Nine patients with the clinical diagnosis of HN were assessed with RCM. A second assessment was performed up to 12 months later. Dermoscopic global patterns were obtained and correlated with the RCM findings. Results: In five (55.6%) cases, pagetoid cells were observed. Nonedged dermal papilla and junctional thickening were found in three (33%) cases. Nucleated cells in the dermal papillae and plump bright cells were observed in seven (77.8%) and six (66.7%) cases, respectively. Conclusion: Our study shows that HN observed by RCM can show atypical features that overlap with those observed on atypical melanocytic lesions and malignant melanoma.

Amyloid β peptide oligomers (AβOs), toxic aggregates with pivotal roles in Alzheimer’s disease, trigger persistent and low magnitude Ca2+ signals in neurons. We reported previously that these Ca2+ signals, which arise from Ca2+ entry and subsequent amplification by Ca2+ release through ryanodine receptor (RyR) channels, promote mitochondrial network fragmentation and reduce RyR2 expression. Here, we examined if AβOs, by inducing redox sensitive RyR-mediated Ca2+ release, stimulate mitochondrial Ca2+-uptake, ROS generation and mitochondrial fragmentation, and also investigated the effects of the antioxidant N-acetyl cysteine (NAC) and the mitochondrial antioxidant EUK-134 on AβOs-induced mitochondrial dysfunction. In addition, we studied the contribution of the RyR2 isoform to AβOs-induced Ca2+ release, mitochondrial Ca2+ uptake and fragmentation. We show here that inhibition of NADPH oxidase type-2 prevented the emergence of RyR-mediated cytoplasmic Ca2+ signals induced by AβOs in primary hippocampal neurons. Treatment with AβOs promoted mitochondrial Ca2+ uptake and increased mitochondrial superoxide and hydrogen peroxide levels; ryanodine, at concentrations that suppress RyR activity, prevented these responses. The antioxidants NAC and EUK-134 impeded the mitochondrial ROS increase induced by AβOs. Additionally, EUK-134 prevented the mitochondrial fragmentation induced by AβOs, as previously reported for NAC and ryanodine. These findings show that both antioxidants, NAC and EUK-134, prevented the Ca2+-mediated noxious effects of AβOs on mitochondrial function. Our results also indicate that Ca2+ release mediated by the RyR2 isoform causes the deleterious effects of AβOs on mitochondrial function. Knockdown of RyR2 with antisense oligonucleotides reduced by about 50% RyR2 mRNA and protein levels in primary hippocampal neurons, decreased by 40% Ca2+ release induced by the RyR agonist 4-chloro-m-cresol, and significantly reduced the cytoplasmic and mitochondrial Ca2+ signals and the mitochondrial fragmentation induced by AβOs. Based on our results, we propose that AβOs-induced Ca2+ entry and ROS generation jointly stimulate RyR2 activity, causing mitochondrial Ca2+ overload and fragmentation in a feed forward injurious cycle. The present novel findings highlight the specific participation of RyR2-mediated Ca2+ release on AβOs-induced mitochondrial malfunction.

Increased reactive oxygen species (ROS) generation and the ensuing oxidative stress contribute to Alzheimer’s disease pathology. We reported previously that amyloid-βpeptide oligomers (AβOs) produce aberrant Ca2+signals at sublethal concentrations and decrease the expression of type-2 ryanodine receptors (RyR2), which are crucial for hippocampal synaptic plasticity and memory. Here, we investigated whether the antioxidant agent astaxanthin (ATX) protects neurons from AβOs-induced excessive mitochondrial ROS generation, NFATc4 activation, and RyR2 mRNA downregulation. To determine mitochondrial H2O2production or NFATc4 nuclear translocation, neurons were transfected with plasmids coding for HyperMito or NFATc4-eGFP, respectively. Primary hippocampal cultures were incubated with 0.1 μM ATX for 1.5 h prior to AβOs addition (500 nM). We found that incubation with ATX (≤10 μM) for ≤24 h was nontoxic to neurons, evaluated by the live/dead assay. Preincubation with 0.1 μM ATX also prevented the neuronal mitochondrial H2O2generation induced within minutes of AβOs addition. Longer exposures to AβOs (6 h) promoted NFATc4-eGFP nuclear translocation and decreased RyR2 mRNA levels, evaluated by detection of the eGFP-tagged fluorescent plasmid and qPCR, respectively. Preincubation with 0.1 μM ATX prevented both effects. These results indicate that ATX protects neurons from the noxious effects of AβOs on mitochondrial ROS production, NFATc4 activation, and RyR2 gene expression downregulation.

ResumenEl cáncer de piel no-melanoma incluye principalmente las neoplasias queratinocíticas (carcinoma basocelular y espinocelular) y tumores de menor frecuencia tales como: linfomas cutáneos, carcinoma de células de Merkel, sarcoma de Kaposi, angiosarcomas, enfermedad de Paget, e histiocistomas malignos entre otros. En este artículo revisaremos la epidemiología, patogénesis, clínica, histopatología, diagnóstico y modalidades terapéuticas de los dos principales cánceres de la piel no melanoma: basocelular y espinocelular.SummaryThe non-melanoma skin cancer refers mainly to the queratinocitic neoplasias (basal cell carcinoma and spinous cell carcinoma) and less frequently tumours like: lymphomas, Merkel cell carcinoma, Kaposi’s Sarcoma, angio sarcomas, Paget disease and malignant hystiocitomas. In this article we will review the epidemiology, pathogenesis, clinical picture, histopathology, diagnosis and treatment of the two more frequent non-melanoma skin cancers: basal cell carcinoma and squamous cell carcinoma.

Glucagonomas are alpha pancreatic islet cell tumors that, when they are active, produce a syndrome characterized by necrolytic migratory erythema, diabetes mellitus, weight loss, anemia, glossitis, thromboembolism, neuropsychiatric disturbances and hyperglucagonemia. We report a 43 years old male presenting with a five years history of dermatological lesions, associated with weight loss, glossitis and onicodystrophy. Serum glucagon was 2200 pg/ml and a CAT scan showed a tumor in the tail of the pancreas. The tumor was surgically excised but one year later, hepatic metastases were found. These were excised surgically, treated with long acting octeotride and finally treated with radiotherapy using Y-DOTATOC. In the last control in November, 2001, the patient is asymptomatic.

ResumenEn el campo de la dermatología en los últimos años se han producido grandes avances en el diagnóstico y tratamiento de las enfermedades cutáneas.La extensión del tegumento, su gran diversidad celular y su fácil accesibilidad han estimulado la realización de múltiples estudios e investigación. De gran relevancia han sido los que han utilizado células madre mesenquimáticas de la piel, ya que tendrán un gran impacto en la medicina de este siglo en relación al aporte terapéutico que esto implica.La farmacogenética, que es el estudio del efecto de la variabilidad genética en un individuo para aumentar las posibilidades de una respuesta terapéutica y disminuir las chances de una reacción adversa a drogas, se acerca al ideal de una medicina personalizada y se ha constituido en una realidad en algunas enfermedades de la piel. Finalmente la fotonanodermatología (interface entre fotobiología, dermatología y nanotecnología), es una tecnología que ha crecido rápidamente en el campo de la medicina y especialmente la dermatología, donde tiene aplicaciones múltiples tanto en productos para la protección de la piel, como en el diagnóstico y tratamiento de enfermedades cutáneas.SummaryIn the dermatology field in the last years, there have been great advances in the diagnosis and treatment of cutaneous diseases. The skin with their large surface and easy accesibility has stimulated the realization of multiplestudies and research.The skin mesenchymal stems cells research is expected to have a great impact on the medicine of the 21st century, specially related with their therapeutic implications.Pharmacogenetics refers to the study of the genetic variability between patients that is been used to optimizate drug efficacy, minimizing toxicity is near the ideal of a personalized medicine and it is being used in some skin diseases. Finally photonanodermatology (interface of photobiology, dermatology and nanotechnology) is a technology that has grown quickly in medicine and specially dermatology, where it has multiple uses in skin protection products and in diagnosis and treatment of skin diseases.