RESUMO
Retinoblastoma, a pediatric ocular malignancy, presents significant challenges in comprehending its molecular underpinnings and targeted therapeutic approaches. The dysregulated activity of histone deacetylases (HDACs) has been associated with retinoblastoma pathogenesis, influencing critical cellular processes like cell cycle regulation or retinal ganglion cell apoptosis. Through their deacetylase activity, HDACs exert control over key tumor suppressors and oncogenes, influencing the delicate equilibrium between proliferation and cell death. Furthermore, the interplay between HDACs and the retinoblastoma protein pathway, a pivotal aspect of retinoblastoma etiology, reveals a complex network of interactions influencing the tumor microenvironment. The examination of HDAC inhibitors, encompassing both established and novel compounds, offers insights into potential approaches to restore acetylation balance and impede retinoblastoma progression. Moreover, the identification of specific HDAC isoforms exhibiting varying expression in retinoblastoma provides avenues for personalized therapeutic strategies, allowing for interventions tailored to individual patient profiles. This review focuses on the intricate interrelationship between HDACs and retinoblastoma, shedding light on epigenetic mechanisms that control tumor development and progression. The exploration of HDAC-targeted therapies underscores the potential for innovative treatment modalities in the pursuit of more efficacious and personalized management strategies for this disease.
Assuntos
Inibidores de Histona Desacetilases , Histona Desacetilases , Retinoblastoma , Retinoblastoma/genética , Retinoblastoma/metabolismo , Retinoblastoma/patologia , Humanos , Histona Desacetilases/metabolismo , Histona Desacetilases/genética , Inibidores de Histona Desacetilases/uso terapêutico , Inibidores de Histona Desacetilases/farmacologia , Animais , Neoplasias da Retina/genética , Neoplasias da Retina/metabolismo , Neoplasias da Retina/patologia , Epigênese Genética , Acetilação , Microambiente Tumoral , Regulação Neoplásica da Expressão Gênica , Proteína do Retinoblastoma/metabolismo , Proteína do Retinoblastoma/genéticaRESUMO
The family of myocyte enhancer factor 2 (MEF2) transcription factors comprises four highly conserved members that play an important role in the nervous system. They appear in precisely defined time frames in the developing brain to turn on and turn off genes affecting growth, pruning and survival of neurons. MEF2s are known to dictate neuronal development, synaptic plasticity and restrict the number of synapses in the hippocampus, thus affecting learning and memory formation. In primary neurons, negative regulation of MEF2 activity by external stimuli or stress conditions is known to induce apoptosis, albeit the pro or antiapoptotic action of MEF2 depends on the neuronal maturation stage. By contrast, enhancement of MEF2 transcriptional activity protects neurons from apoptotic death both in vitro and in preclinical models of neurodegenerative diseases. A growing body of evidence places this transcription factor in the center of many neuropathologies associated with age-dependent neuronal dysfunctions or gradual but irreversible neuron loss. In this work, we discuss how the altered function of MEF2s during development and in adulthood affecting neuronal survival may be linked to neuropsychiatric disorders.
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Apoptose , Regulação da Expressão Gênica , Fatores de Transcrição MEF2/genética , Encéfalo/metabolismo , Neurônios/metabolismoRESUMO
The activity of specific populations of neurons in different brain areas makes decisions regarding proper synaptic transmission, the ability to make adaptations in response to different external signals, as well as the triggering of specific regulatory pathways to sustain neural function. The endocannabinoid system (ECS) appears to be a very important, highly expressed, and active system of control in the central nervous system (CNS). Functionally, it allows the cells to respond quickly to processes that occur during synaptic transmission, but can also induce long-term changes. The endocannabinoids (eCBs) belong to a large family of bioactive lipid mediators that includes amides, esters, and ethers of long-chain polyunsaturated fatty acids. They are produced "on demand" from the precursors located in the membranes, exhibit a short half-life, and play a key role as retrograde messengers. eCBs act mainly through two receptors, CB1R and CB2R, which belong to the G-protein coupled receptor superfamily (GPCRs), but can also exert their action via multiple non-receptor pathways. The action of eCBs depends on Ca2+, but eCBs can also regulate downstream Ca2+ signaling. In this short review, we focus on the regulation of neuronal calcium channels by the most effective members of eCBs-2-arachidonoylglycerol (2-AG), anandamide (AEA) and originating from AEA-N-arachidonoylglycine (NAGly), to better understand the contribution of ECS to brain function under physiological conditions.
Assuntos
Encéfalo/metabolismo , Canais de Cálcio/metabolismo , Cálcio/metabolismo , Endocanabinoides/metabolismo , Transmissão Sináptica , Animais , Humanos , Receptor CB1 de Canabinoide/metabolismo , Receptor CB2 de Canabinoide/metabolismo , Transdução de SinaisRESUMO
Calcium in mammalian neurons is essential for developmental processes, neurotransmitter release, apoptosis, and signal transduction. Incorrectly processed Ca2+ signal is well-known to trigger a cascade of events leading to altered response to variety of stimuli and persistent accumulation of pathological changes at the molecular level. To counterbalance potentially detrimental consequences of Ca2+, neurons are equipped with sophisticated mechanisms that function to keep its concentration in a tightly regulated range. Calcium pumps belonging to the P-type family of ATPases: plasma membrane Ca2+-ATPase (PMCA), sarco/endoplasmic Ca2+-ATPase (SERCA) and secretory pathway Ca2+-ATPase (SPCA) are considered efficient line of defense against abnormal Ca2+ rises. However, their role is not limited only to Ca2+ transport, as they present tissue-specific functionality and unique sensitive to the regulation by the main calcium signal decoding protein-calmodulin (CaM). Based on the available literature, in this review we analyze the contribution of these three types of Ca2+-ATPases to neuropathology, with a special emphasis on mental diseases.
Assuntos
ATPases Transportadoras de Cálcio/metabolismo , Transtornos Mentais/enzimologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Animais , ATPases Transportadoras de Cálcio/química , Humanos , Modelos Moleculares , Doenças do Sistema Nervoso/enzimologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/química , Conformação Proteica , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/químicaRESUMO
cAMP signaling is known to be critical in neuronal survival and axon growth. Increasingly the subcellular compartmentation of cAMP signaling has been appreciated, but outside of dendritic synaptic regulation, few cAMP compartments have been defined in terms of molecular composition or function in neurons. Specificity in cAMP signaling is conferred in large part by A-kinase anchoring proteins (AKAPs) that localize protein kinase A and other signaling enzymes to discrete intracellular compartments. We now reveal that cAMP signaling within a perinuclear neuronal compartment organized by the large multivalent scaffold protein mAKAPα promotes neuronal survival and axon growth. mAKAPα signalosome function is explored using new molecular tools designed to specifically alter local cAMP levels as studied by live-cell FRET imaging. In addition, enhancement of mAKAPα-associated cAMP signaling by isoform-specific displacement of bound phosphodiesterase is demonstrated to increase retinal ganglion cell survival in vivo in mice of both sexes following optic nerve crush injury. These findings define a novel neuronal compartment that confers cAMP regulation of neuroprotection and axon growth and that may be therapeutically targeted in disease.SIGNIFICANCE STATEMENT cAMP is a second messenger responsible for the regulation of diverse cellular processes including neuronal neurite extension and survival following injury. Signal transduction by cAMP is highly compartmentalized in large part because of the formation of discrete, localized multimolecular signaling complexes by A-kinase anchoring proteins. Although the concept of cAMP compartmentation is well established, the function and identity of these compartments remain poorly understood in neurons. In this study, we provide evidence for a neuronal perinuclear cAMP compartment organized by the scaffold protein mAKAPα that is necessary and sufficient for the induction of neurite outgrowth in vitro and for the survival of retinal ganglion cells in vivo following optic nerve injury.
Assuntos
Orientação de Axônios , AMP Cíclico/metabolismo , Células Ganglionares da Retina/metabolismo , Transdução de Sinais , Proteínas de Ancoragem à Quinase A/metabolismo , Animais , Axônios/metabolismo , Axônios/fisiologia , Células COS , Células Cultivadas , Chlorocebus aethiops , Feminino , Transferência Ressonante de Energia de Fluorescência , Masculino , Camundongos , Diester Fosfórico Hidrolases/metabolismo , Ratos , Ratos Sprague-Dawley , Células Ganglionares da Retina/citologia , Células Ganglionares da Retina/fisiologiaRESUMO
Ketamine is a non-competitive antagonist of NMDA (N-methyl-D-aspartate) receptor, which has been in clinical practice for over a half century. Despite recent data suggesting its harmful side effects, such as neuronal loss, synapse dysfunction or disturbed neural network formation, the drug is still applied in veterinary medicine and specialist anesthesia. Several lines of evidence indicate that structural and functional abnormalities in the nervous system caused by ketamine are crosslinked with the imbalanced activity of multiple Ca2+-regulated signaling pathways. Due to its ubiquitous nature, Ca2+ is also frequently located in the center of ketamine action, although the precise mechanisms underlying drug's negative or therapeutic properties remain mysterious for the large part. This review seeks to delineate the relationship between ketamine-triggered imbalance in Ca2+ homeostasis and functional consequences for downstream processes regulating key aspects of neuronal function.
Assuntos
Sinalização do Cálcio/efeitos dos fármacos , Cálcio/metabolismo , Ketamina/efeitos adversos , Neurônios/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Animais , Humanos , Neurônios/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/efeitos dos fármacos , Sinapses/metabolismoRESUMO
The aging process is a physiological phenomenon associated with progressive changes in metabolism, genes expression, and cellular resistance to stress. In neurons, one of the hallmarks of senescence is a disturbance of calcium homeostasis that may have far-reaching detrimental consequences on neuronal physiology and function. Among several proteins involved in calcium handling, plasma membrane Ca2+-ATPase (PMCA) is the most sensitive calcium detector controlling calcium homeostasis. PMCA exists in four main isoforms and PMCA2 and PMCA3 are highly expressed in the brain. The overall effects of impaired calcium extrusion due to age-dependent decline of PMCA function seem to accumulate with age, increasing the susceptibility to neurotoxic insults. To analyze the PMCA role in neuronal cells, we have developed stable transfected differentiated PC12 lines with down-regulated PMCA2 or PMCA3 isoforms to mimic age-related changes. The resting Ca2+ increased in both PMCA-deficient lines affecting the expression of several Ca2+-associated proteins, i.e., sarco/endoplasmic Ca2+-ATPase (SERCA), calmodulin, calcineurin, GAP43, CCR5, IP3Rs, and certain types of voltage-gated Ca2+ channels (VGCCs). Functional studies also demonstrated profound changes in intracellular pH regulation and mitochondrial metabolism. Moreover, modification of PMCAs membrane composition triggered some adaptive processes to counterbalance calcium overload, but the reduction of PMCA2 appeared to be more detrimental to the cells than PMCA3.
Assuntos
Envelhecimento/metabolismo , Neurônios/enzimologia , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Animais , Humanos , Isoenzimas/metabolismo , Mitocôndrias/metabolismo , Modelos Biológicos , Neurônios/citologiaRESUMO
Calmodulin (CaM) is well known as an activator of calcium/calmodulin-dependent protein kinase II (CaMKII). Voltage-gated sodium channels (VGSCs) are basic signaling molecules in excitable cells and are crucial molecular targets for nervous system agents. However, the way in which Ca2+/CaM/CaMKII cascade modulates NaV1.1 IQ (isoleucine and glutamine) domain of VGSCs remains obscure. In this study, the binding of CaM, its mutants at calcium binding sites (CaM12, CaM34, and CaM1234), and truncated proteins (N-lobe and C-lobe) to NaV1.1 IQ domain were detected by pull-down assay. Our data showed that the binding of Ca2+/CaM to the NaV1.1 IQ was concentration-dependent. ApoCaM (Ca2+-free form of calmodulin) bound to NaV1.1 IQ domain preferentially more than Ca2+/CaM. Additionally, the C-lobe of CaM was the predominant domain involved in apoCaM binding to NaV1.1 IQ domain. By contrast, the N-lobe of CaM was predominant in the binding of Ca2+/CaM to NaV1.1 IQ domain. Moreover, CaMKII-mediated phosphorylation increased the binding of Ca2+/CaM to NaV1.1 IQ domain due to one or several phosphorylation sites in T1909, S1918, and T1934 of NaV1.1 IQ domain. This study provides novel mechanisms for the modulation of NaV1.1 by the Ca2+/CaM/CaMKII axis. For the first time, we uncover the effect of Ca2+, lobe-specificity and CaMKII on CaM binding to NaV1.1.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/química , Cálcio/química , Calmodulina/química , Canal de Sódio Disparado por Voltagem NAV1.1/química , Sequência de Aminoácidos , Sítios de Ligação , Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Calmodulina/genética , Calmodulina/metabolismo , Clonagem Molecular , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Glutationa Transferase/química , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Células HEK293 , Humanos , Cinética , Simulação de Acoplamento Molecular , Mutação , Canal de Sódio Disparado por Voltagem NAV1.1/genética , Canal de Sódio Disparado por Voltagem NAV1.1/metabolismo , Fosforilação , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , TermodinâmicaRESUMO
Chronic N-methyl-D-aspartate receptor (NMDAR) antagonist treatment can provide valuable neurochemical and neuroanatomical models of experimental psychosis. One such antagonist, ketamine, with its short half-time and well-documented psychotomimetic action, has cognitive effects resembling various aspects of schizophrenia-like symptoms. In order to obtain insights into possible relationships between Ca(2+) homeostasis and schizophrenia-related symptoms, we investigate the effects of chronic ketamine administration on intracellular Ca(2+) levels in various brain regions and on the expression level of key members of the neuronal Ca(2+)-handling system in rats. We show increased intracellular [Ca(2+)] in all of the examined brain regions following ketamine treatment but an altered cytosolic Ca(2+) level correlated with hyperlocomotor activity was only established for the cortex and striatum. Our findings also suggest that an imbalance in the expression between the calcium "on" and "off" systems contributes to the deregulation of brain Ca(2+) homeostasis in our ketamine-induced model of experimental psychosis. Identification of the genes whose expression is affected by ketamine treatment indicates their involvement as putative etiological factors in schizophrenia.
Assuntos
Cálcio/metabolismo , Transtornos Psicóticos/metabolismo , Transtornos Psicóticos/patologia , Animais , Comportamento Animal , Encéfalo/metabolismo , Encéfalo/patologia , Separação Celular , Sobrevivência Celular , Modelos Animais de Doenças , Regulação da Expressão Gênica , Homeostase , Espaço Intracelular/metabolismo , Ketamina , Masculino , Atividade Motora , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Ketamine, a high affinity uncompetitive antagonist of voltage-dependent NMDA receptor, has been used for years as a dissociative anesthetic. Although the drug is considered as safe and well-tolerable, it is now evident that it can exert dose-dependent multidirectional effects acting on different cellular targets and pathways. The latest clinical studies also demonstrated its promising antidepressant action. However, the widespread use of this drug in humans is largely limited by a broad range of cognitive adverse effects that resemble some core symptoms of schizophrenia. In line with the hypothesis of unifying role of calcium in schizophrenia symptomology, we used ketamine-induced rat model of experimental psychosis to study the effect of 5-day ketamine treatment (30 mg/kg, ip) on the activity of plasma membrane Ca(2+)-ATPase. Whereas no change in a total amount of the enzyme in cortical synaptosomal membranes was observed, a decrease by â¼50% in hydrolytic activity, as well as lowered phosphointermediate formation were detected. Moreover, ketamine action appeared to be isoform-independent. The experiments on intact Ca(2+)-ATPase purified from vehicle-treated rat cortex revealed dose-dependent inhibition of enzymatic activity. Furthermore, ketamine decreased, but not eliminated, the stimulation by calmodulin. The inhibitory effect, although much weaker, was also evident for truncated form of calcium pump obtained following digestion by trypsin. Our results indicate that plasma membrane Ca(2+)-ATPase is a novel target for ketamine and putative interaction sites may involve central catalytic loop and calmodulin-binding domain.
Assuntos
Cálcio/metabolismo , Membrana Celular/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Esquizofrenia/metabolismo , Sinaptossomos/efeitos dos fármacos , Anestésicos Dissociativos , Animais , Calmodulina/metabolismo , Calmodulina/farmacologia , Domínio Catalítico , Membrana Celular/metabolismo , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Modelos Animais de Doenças , Transporte de Íons , Isoenzimas/química , Isoenzimas/metabolismo , Ketamina , Masculino , ATPases Transportadoras de Cálcio da Membrana Plasmática/química , Ligação Proteica , Estrutura Secundária de Proteína , Ratos , Ratos Wistar , Esquizofrenia/induzido quimicamente , Esquizofrenia/patologia , Sinaptossomos/metabolismoRESUMO
Several lines of evidence suggest the contribution of age-related decline in plasma membrane calcium pump (PMCA) to the onset of neurodegenerative diseases. From four PMCA isoforms, PMCA2, and PMCA3 respond to a rapid removal of Ca(2+) and are expressed predominantly in excitable cells. We have previously shown that suppression of neuron-specific PMCAs in differentiated PC12 cells accelerated cell differentiation, but increased apoptosis in PMCA2-deficient line. We also demonstrated that altered expression of voltage-dependent calcium channels correlated with their higher contribution to Ca(2+) influx, which varied between PMCA-reduced lines. Here, we propose a mechanism unique for differentiated PC12 cells by which PMCA2 and PMCA3 regulate pGAP43/GAP43 ratio and the interaction between GAP43 and calmodulin (CaM). Although down-regulation of PMCA2 or PMCA3 altered the content of GAP43/pGAP43, of paramount importance for the regulatory mechanism is a disruption of isoform-specific inhibitory PMCA/calcineurin interaction. In result, higher endogenous calcineurin (CaN) activity leads to hypophosphorylation of GAP43 in PMCA2- or PMCA3-deficient lines and intensification of GAP43/CaM complex formation, thus potentially limiting the availability of free CaM. In overall, our results indicate that both "fast" PMCA isoforms could actively regulate the local CaN function and CaN-downstream processes. In connection with our previous observations, we also suggest a negative feedback of cooperative action of CaM, GAP43, and CaN on P/Q and L-type channels activity. PMCAs- and CaN-dependent mechanism presented here, may signify a protective action against calcium overload in neuronal cells during aging, as well a potential way for decreasing neuronal cells vulnerability to neurodegenerative insults.
Assuntos
Calcineurina/metabolismo , Calmodulina/metabolismo , Proteína GAP-43/metabolismo , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Animais , Diferenciação Celular , Linhagem Celular , Regulação da Expressão Gênica , Fosforilação , Isoformas de Proteínas/metabolismo , Ratos , Transdução de SinaisRESUMO
Both Ca2+ and protein kinase A (PKA) are multifaceted and ubiquitous signaling molecules, essential for regulating the intricate network of signaling pathways. However, their dynamics within specialized membrane regions are still not well characterized. By using genetically encoded fluorescent indicators specifically targeted to distinct plasma membrane microdomains, we have established a protocol that permits observing Ca2+/PKA dynamics in discrete neuronal microdomains with high spatial and temporal resolution. The approach employs a fluorescence microscope with a sensitive camera and a dedicated CFP/YFP/mCherry filter set, enabling the simultaneous detection of donor-acceptor emission and red fluorescence signal. In this detailed step-by-step guide, we outline the experimental procedure, including isolation of rat primary neurons and their transfection with biosensors targeted to lipid rafts or non-raft regions of plasma membrane. We provide information on the necessary equipment and imaging setup required for recording, along with highlighting critical parameters and troubleshooting guidelines for real-time measurements. Finally, we provide examples of the observed Ca2+ and PKA changes in specific cellular compartments. The application of this technique may have significant implications for studying cross-talk between second messengers and their alterations in various pathological conditions. © 2024 Wiley Periodicals LLC.
Assuntos
Cálcio , Proteínas Quinases Dependentes de AMP Cíclico , Transferência Ressonante de Energia de Fluorescência , Hipocampo , Microdomínios da Membrana , Neurônios , Animais , Neurônios/metabolismo , Hipocampo/metabolismo , Hipocampo/citologia , Ratos , Cálcio/metabolismo , Microdomínios da Membrana/metabolismo , Transferência Ressonante de Energia de Fluorescência/métodos , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Células Cultivadas , Microscopia de Fluorescência/métodos , Técnicas Biossensoriais/métodosRESUMO
The dysregulation of intracellular calcium levels is a critical factor in neurodegeneration, leading to the aberrant activation of calcium-dependent processes and, ultimately, cell death. Ca2+ signals vary in magnitude, duration, and the type of neuron affected. A moderate Ca2+ concentration can initiate certain cellular repair pathways and promote neuroregeneration. While the peripheral nervous system exhibits an intrinsic regenerative capability, the central nervous system has limited self-repair potential. There is evidence that significant variations exist in evoked calcium responses and axonal regeneration among neurons, and individual differences in regenerative capacity are apparent even within the same type of neurons. Furthermore, some studies have shown that neuronal activity could serve as a potent regulator of this process. The spatio-temporal patterns of calcium dynamics are intricately controlled by a variety of proteins, including channels, ion pumps, enzymes, and various calcium-binding proteins, each of which can exert either positive or negative effects on neural repair, depending on the cellular context. In this concise review, we focus on several calcium-associated proteins such as CaM kinase II, GAP-43, oncomodulin, caldendrin, calneuron, and NCS-1 in order to elaborate on their roles in the intrinsic mechanisms governing neuronal regeneration following traumatic damage processes.
Assuntos
Cálcio , Neurônios , Cálcio/metabolismo , Neurônios/metabolismo , Sinalização do Cálcio/fisiologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Regeneração NervosaRESUMO
Retinal ganglion cells (RGCs), neurons transmitting visual information via the optic nerve, fail to regenerate their axons after injury. The progressive loss of RGC function underlies the pathophysiology of glaucoma and other optic neuropathies, often leading to irreversible blindness. Therefore, there is an urgent need to identify the regulators of RGC survival and the regenerative program. In this study, we investigated the role of the family of transcription factors known as nuclear factor of activated T cells (NFAT), which are expressed in the retina; however, their role in RGC survival after injury is unknown. Using the optic nerve crush (ONC) model, widely employed to study optic neuropathies and central nervous system axon injury, we found that NFATc4 is specifically but transiently up-regulated in response to mechanical injury. In the injured retina, NFATc4 immunolocalized primarily to the ganglionic cell layer. Utilizing NFATc4-/- and NFATc3-/- mice, we demonstrated that NFATc4, but not NFATc3, knockout increased RGC survival, improved retina function, and delayed axonal degeneration. Microarray screening data, along with decreased immunostaining of cleaved caspase-3, revealed that NFATc4 knockout was protective against ONC-induced degeneration by suppressing pro-apoptotic signaling. Finally, we used lentiviral-mediated NFATc4 delivery to the retina of NFATc4-/- mice and reversed the pro-survival effect of NFATc4 knockout, conclusively linking the enhanced survival of injured RGCs to NFATc4-dependent mechanisms. In summary, this study is the first to demonstrate that NFATc4 knockout may confer transient RGC neuroprotection and decelerate axonal degeneration after injury, providing a potent therapeutic strategy for optic neuropathies.
Assuntos
Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores de Transcrição NFATC , Regeneração Nervosa , Neuroproteção , Traumatismos do Nervo Óptico , Células Ganglionares da Retina , Animais , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/patologia , Traumatismos do Nervo Óptico/metabolismo , Traumatismos do Nervo Óptico/patologia , Fatores de Transcrição NFATC/metabolismo , Regeneração Nervosa/fisiologia , Sobrevivência Celular , Apoptose , Axônios/metabolismo , Axônios/patologia , CamundongosRESUMO
The complex nature of the retina demands well-organized signaling to uphold signal accuracy and avoid interference, a critical aspect in handling a variety of visual stimuli. A-kinase anchoring proteins (AKAPs), known for binding protein kinase A (PKA), contribute to the specificity and efficiency of retinal signaling. They play multifaceted roles in various retinal cell types, influencing photoreceptor sensitivity, neurotransmitter release in bipolar cells, and the integration of visual information in ganglion cells. AKAPs like AKAP79/150 and AKAP95 exhibit distinct subcellular localizations, impacting synaptic transmission and receptor sensitivity in photoreceptors and bipolar cells. Furthermore, AKAPs are involved in neuroprotective mechanisms and axonal degeneration, particularly in retinal ganglion cells. In particular, AKAP6 coordinates stress-specific signaling and promotes neuroprotection following optic nerve injury. As our review underscores the therapeutic potential of targeting AKAP signaling complexes for retinal neuroprotection and enhancement, it acknowledges challenges in developing selective drugs that target complex protein-protein interactions. Overall, this exploration of AKAPs provides valuable insights into the intricacies of retinal signaling, offering a foundation for understanding and potentially addressing retinal disorders.
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Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive functions. While the exact causes of this debilitating disorder remain elusive, numerous investigations have characterized its two core pathologies: the presence of ß-amyloid plaques and tau tangles. Additionally, multiple studies of postmortem brain tissue, as well as results from AD preclinical models, have consistently demonstrated the presence of a sustained inflammatory response. As the persistent immune response is associated with neurodegeneration, it became clear that it may also exacerbate other AD pathologies, providing a link between the initial deposition of ß-amyloid plaques and the later development of neurofibrillary tangles. Initially discovered in T cells, the nuclear factor of activated T-cells (NFAT) is one of the main transcription factors driving the expression of inflammatory genes and thus regulating immune responses. NFAT-dependent production of inflammatory mediators is controlled by Ca2+-dependent protein phosphatase calcineurin (CaN), which dephosphorylates NFAT and promotes its transcriptional activity. A substantial body of evidence has demonstrated that aberrant CaN/NFAT signaling is linked to several pathologies observed in AD, including neuronal apoptosis, synaptic deficits, and glia activation. In view of this, the role of NFAT isoforms in AD has been linked to disease progression at different stages, some of which are paralleled to diminished cognitive status. The use of classical inhibitors of CaN/NFAT signaling, such as tacrolimus or cyclosporine, or adeno-associated viruses to specifically inhibit astrocytic NFAT activation, has alleviated some symptoms of AD by diminishing ß-amyloid neurotoxicity and neuroinflammation. In this article, we discuss the recent findings related to the contribution of CaN/NFAT signaling to the progression of AD and highlight the possible benefits of targeting this pathway in AD treatment.
Assuntos
Doença de Alzheimer , Humanos , Doença de Alzheimer/metabolismo , Calcineurina/metabolismo , Placa Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismoRESUMO
Vitamin C (ascorbic acid) is well known for its potent antioxidant properties, as it can neutralize ROS and free radicals, thereby protecting cellular elements from oxidative stress. It predominantly exists as an ascorbate anion and after oxidation to dehydroascorbic acid and further breakdown, is removed from the cells. In nervous tissue, a progressive decrease in vitamin C level or its prolonged deficiency have been associated with an increased risk of disturbances in neurotransmission, leading to dysregulation in brain function. Therefore, understanding the regulatory function of vitamin C in antioxidant defence and identification of its molecular targets deserves more attention. One of the key signalling ions is calcium and a transient rise in its concentration is crucial for all neuronal processes. Extracellular Ca2+ influx (through specific ion channels) or Ca2+ release from intracellular stores (endoplasmic reticulum, mitochondria) are precisely controlled. Ca2+ regulates the functioning of the CNS, including growth, development, myelin formation, synthesis of catecholamines, modulation of neurotransmission and antioxidant protection. A growing body of evidence indicates a unique role for vitamin C in these processes. In this short review, we focus on vitamin C in the regulation of calcium-involved pathways under physiological and stress conditions in the brain.
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Cellular calcium homeostasis is controlled predominantly by the plasma membrane calcium pump (PMCA). From four PMCA isoforms, PMCA1 and PMCA4 are ubiquitous, while PMCA2 and PMCA3 are found in excitable cells. We have previously shown that suppression of neuron-specific PMCAs in non-differentiated PC12 cells changed the cell morphology and triggered neuritogenesis. Using the microarrays, real-time PCR and immunodetection, we analyzed the effect of PMCA2 or PMCA3 reduction in PC12 cells on gene expression, with emphasis on calmodulin (CaM), neuromodulin (GAP43) and MAP kinases. In PMCA-suppressed lines total CaM increased, and the calm I and calm II genes appeared to be responsible for this effect. mRNA and protein levels of GAP43 were increased, however, the amount of phosphorylated form was lower than in control cells. Localization of CaM/GAP43 and CaM/pGAP43 differed between control and PMCA-reduced cells. In both PMCA-modified lines, amounts of ERK1/2 increased. While pERK1 decreased, the pERK2 level was similar in all examined lines. PMCA suppression did not change the p38 amount, but the p-p38 diminished. JNK2 protein decreased in both PMCA-reduced cells without changes in pJNK level. Microarray analysis revealed distinct expression patterns of certain genes involved in the regulation of cell cycle, proliferation, migration, differentiation, apoptosis and cell signaling. Suppression of neuron-specific PMCA isoforms affected the phenotype of PC12 cells enabling adaptation to the sustained increase in cytosolic Ca(2+) concentration. This is the first report showing function of PMCA2 and PMCA3 isoforms in the regulation of signaling pathways in PC12 cells.
Assuntos
Calmodulina/metabolismo , Proteína GAP-43/metabolismo , ATPases Transportadoras de Cálcio da Membrana Plasmática/genética , Regulação para Cima , Animais , Cálcio/metabolismo , Sinalização do Cálcio , Calmodulina/genética , Fenômenos Fisiológicos Celulares/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteína GAP-43/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Células PC12 , Fosforilação , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Isoformas de Proteínas/metabolismo , Transporte Proteico , RatosRESUMO
Calmodulin (CaM) is a sensor protein, which takes part in calcium-dependent signaling, regulating processes like growth, differentiation, proliferation and motility. Calmodulin binds calcium ions during induction of intracellular signaling. It is also involved in silencing of calcium signal through activation of plasma membrane Ca(2+)-ATPase (directly) or SERCA pump (indirectly). Calmodulin may affect various channels, e.g. voltage gated calcium channels (VGCCs), transient receptor potential channels (TRPCs), NMDA receptors, calcium channels dependent on cyclic nucleotides or these located in endoplasmic reticulum (ryanodine receptors and all isoforms of IP3-dependent receptors).
Assuntos
Sinalização do Cálcio/fisiologia , Calmodulina/metabolismo , Animais , Canais de Cálcio/metabolismo , Diferenciação Celular/fisiologia , Membrana Celular/metabolismo , Movimento Celular/fisiologia , Proliferação de Células , Retículo Endoplasmático/metabolismo , Humanos , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Canais de Potencial de Receptor Transitório/metabolismoRESUMO
It is commonly accepted that the role of astrocytes exceeds far beyond neuronal scaffold and energy supply. Their unique morphological and functional features have recently brough much attention as it became evident that they play a fundamental role in neurotransmission and interact with synapses. Synaptic transmission is a highly orchestrated process, which triggers local and transient elevations in intracellular Ca2+, a phenomenon with specific temporal and spatial properties. Presynaptic activation of Ca2+-dependent adenylyl cyclases represents an important mechanism of synaptic transmission modulation. This involves activation of the cAMP-PKA pathway to regulate neurotransmitter synthesis, release and storage, and to increase neuroprotection. This aspect is of paramount importance for the preservation of neuronal survival and functionality in several pathological states occurring with progressive neuronal loss. Hence, the aim of this review is to discuss mutual relationships between cAMP and Ca2+ signaling and emphasize those alterations at the Ca2+/cAMP crosstalk that have been identified in neurodegenerative disorders, such as Alzheimer's and Parkinson's disease.