RESUMO
BACKGROUND: Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TH17 cells may be beneficial in psoriasis. We found that Cav1.4, encoded by CACNA1F, was the only Cav1 calcium channel expressed in TH17 cells. OBJECTIVE: We sought to investigate the role of Cav1.4 expression in early TH17-activation events and effector functions, as well as its association with TH17 signature genes in lesional psoriatic (LP) skins. METHODS: Transcriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. Cav1 inhibitor and/or shRNA lentivectors were used to assess the contribution of Cav1.4 in TH17 activation and effector functions in a 3-dimensional skin reconstruction model. RESULTS: CACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4+ and CD4- cells from LP biopsies. Nicardipine, a Cav1 channel antagonist, markedly reduced inflammatory cytokine production by TH17 cells from blood or LP skin. This was associated with decreased TCR-induced early calcium events at cell membrane and proximal signaling events. The knockdown of Cav1.4 in TH17 cells impaired cytokine production. Finally, Cav1 inhibition reduced the expression of the keratinocyte genes characteristic of TH17-mediated psoriasis inflammation in human skin equivalents. CONCLUSIONS: Cav1.4 channels promote TH17-cell functions both at the periphery and in inflammatory psoriatic skin.
Assuntos
Canais de Cálcio , Psoríase , Canais de Cálcio/metabolismo , Citocinas/metabolismo , Humanos , Inflamação/metabolismo , Psoríase/metabolismo , Pele/patologia , Células Th17/patologiaRESUMO
Glioblastoma is the most common malignant brain tumor. The heterogeneity at the cellular level, metabolic specificities and plasticity of the cancer cells are a challenge for glioblastoma treatment. Identification of cancer cells endowed with stem properties and able to propagate the tumor in animal xenografts has opened a new paradigm in cancer therapy. Thus, to increase efficacy and avoid tumor recurrence, therapies need to target not only the differentiated cells of the tumor mass, but also the cancer stem-like cells. These therapies need to be effective on cells present in the hypoxic, slightly acidic microenvironment found within tumors. Such a microenvironment is known to favor more aggressive undifferentiated phenotypes and a slow-growing "quiescent state" that preserves the cells from chemotherapeutic agents, which mostly target proliferating cells. Based on these considerations, we performed a differential screening of the Prestwick Chemical Library of approved drugs on both proliferating and quiescent glioblastoma stem-like cells and identified bisacodyl as a cytotoxic agent with selectivity for quiescent glioblastoma stem-like cells. In the present study we further characterize bisacodyl activity and show its efficacy in vitro on clonal macro-tumorospheres, as well as in vivo in glioblastoma mouse models. Our work further suggests that bisacodyl acts through inhibition of Ca2+ release from the InsP3 receptors.
Assuntos
Bisacodil/farmacologia , Neoplasias Encefálicas/patologia , Sinalização do Cálcio , Glioblastoma/patologia , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Células-Tronco Neoplásicas/patologia , Neoplasias Encefálicas/metabolismo , Linhagem Celular Tumoral , Glioblastoma/metabolismo , Humanos , Células-Tronco Neoplásicas/metabolismoRESUMO
While it is a relatively rare disease, glioblastoma multiform (GBM) is one of the more deadly adult cancers. Following current interventions, the tumor is never eliminated whatever the treatment performed; whether it is radiotherapy, chemotherapy, or surgery. One hypothesis to explain this poor outcome is the "cancer stem cell" hypothesis. This concept proposes that a minority of cells within the tumor mass share many of the properties of adult neural stem cells and it is these that are responsible for the growth of the tumor and its resistance to existing therapies. Accumulating evidence suggests that Ca(2+) might also be an important positive regulator of tumorigenesis in GBM, in processes involving quiescence, maintenance, proliferation, or migration. Glioblastoma tumors are generally thought to develop by co-opting pathways that are involved in the formation of an organ. We propose that the cells initiating the tumor, and subsequently the cells of the tumor mass, must hijack the different checkpoints that evolution has selected in order to prevent the pathological development of an organ. In this article, two main points are discussed. (i) The first is the establishment of a so-called "cellular society," which is required to create a favorable microenvironment. (ii) The second is that GBM can be considered to be an organism, which fights to survive and develop. Since GBM evolves in a limited space, its only chance of development is to overcome the evolutionary checkpoints. For example, the deregulation of the normal Ca(2+) signaling elements contributes to the progression of the disease. Thus, by manipulating the Ca(2+) signaling, the GBM cells might not be killed, but might be reprogrammed toward a new fate that is either easy to cure or that has no aberrant functioning. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.
Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Glioblastoma/metabolismo , Células-Tronco Neoplásicas/metabolismo , Animais , Proliferação de Células/genética , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Glioblastoma/genética , Glioblastoma/terapia , Humanos , Células-Tronco Neoplásicas/patologia , Microambiente Tumoral/genéticaRESUMO
In Xenopus laevis embryos, kidney field specification is dependent on retinoic acid (RA) and coincides with a dramatic increase of Ca(2+) transients, but the role of Ca(2+) signaling in the kidney field is unknown. Here, we identify TRPP2, a member of the transient receptor potential (TRP) superfamily of channel proteins encoded by the pkd2 gene, as a central component of Ca(2+) signaling in the kidney field. TRPP2 is strongly expressed at the plasma membrane where it might regulate extracellular Ca(2+) entry. Knockdown of pkd2 in the kidney field results in the downregulation of pax8, but not of other kidney field genes (lhx1, osr1 and osr2). We further show that inhibition of Ca(2+) signaling with an inducible Ca(2+) chelator also causes downregulation of pax8, and that pkd2 knockdown results in a severe inhibition of Ca(2+) transients in kidney field explants. Finally, we show that disruption of RA results both in an inhibition of intracellular Ca(2+) signaling and of TRPP2 incorporation into the plasma membrane of kidney field cells. We propose that TRPP2-dependent Ca(2+) signaling is a key component of pax8 regulation in the kidney field downstream of RA-mediated non-transcriptional control of TRPP2.
Assuntos
Sinalização do Cálcio/fisiologia , Embrião não Mamífero/embriologia , Rim/embriologia , Fatores de Transcrição Box Pareados/metabolismo , Canais de Cátion TRPP/metabolismo , Proteínas de Xenopus/metabolismo , Animais , Embrião não Mamífero/citologia , Rim/citologia , Fator de Transcrição PAX8 , Fatores de Transcrição Box Pareados/genética , Canais de Cátion TRPP/genética , Proteínas de Xenopus/genética , Xenopus laevisRESUMO
In amphibian embryos, our previous work has demonstrated that calcium transients occurring in the dorsal ectoderm at the onset of gastrulation are necessary and sufficient to engage the ectodermal cells into a neural fate by inducing neural specific genes. Some of these genes are direct targets of calcium. Here we search for a direct transcriptional mechanism by which calcium signals are acting. The only known mechanism responsible for a direct action of calcium on gene transcription involves an EF-hand Ca²âº binding protein which belongs to a group of four proteins (Kcnip1 to 4). Kcnip protein can act in a Ca²âº-dependent manner as a transcriptional repressor by binding to a specific DNA sequence, the Downstream Regulatory Element (DRE) site. In Xenopus, among the four kcnips, we show that only kcnip1 is timely and spatially present in the presumptive neural territories and is able to bind DRE sites in a Ca²âº-dependent manner. The loss of function of kcnip1 results in the expansion of the neural plate through an increased proliferation of neural progenitors. Later on, this leads to an impairment in the development of anterior neural structures. We propose that, in the embryo, at the onset of neurogenesis Kcnip1 is the Ca²âº-dependent transcriptional repressor that controls the size of the neural plate. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
Assuntos
Cálcio/metabolismo , Embrião não Mamífero/embriologia , Proteínas Interatuantes com Canais de Kv/metabolismo , Placa Neural/embriologia , Proteínas Repressoras/metabolismo , Proteínas de Xenopus/metabolismo , Animais , Embrião não Mamífero/citologia , Proteínas Interatuantes com Canais de Kv/genética , Placa Neural/citologia , Neurogênese/fisiologia , Proteínas Repressoras/genética , Elementos de Resposta , Proteínas de Xenopus/genética , Xenopus laevisRESUMO
To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR.
Assuntos
Aphanomyces/metabolismo , Dano ao DNA , Proteínas de Ligação a DNA/metabolismo , Células Eucarióticas/metabolismo , Medicago truncatula/microbiologia , Proteínas/metabolismo , Sequência de Aminoácidos , Animais , Núcleo Celular/metabolismo , Tamanho Celular , DNA de Plantas/metabolismo , Transferência Ressonante de Energia de Fluorescência , Regulação da Expressão Gênica de Plantas , Microinjeções , Phytophthora/fisiologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Ligação Proteica , Transporte Proteico , Nicotiana/microbiologia , Xenopus laevis/embriologiaRESUMO
In vertebrates, the formation of the nervous system starts at gastrulation with a process called neural induction. This process requires, at least in part, the inhibition of BMP signalling in the ectoderm by noggin, as well as FGF receptor activation and Ca2+ signalling. Our studies with Xenopus embryos suggest that an increase in intracellular Ca2+ concentration ([Ca2+]i), via dihydropyridine-sensitive Ca2+ channels (DHP-sensitive Ca2+ channels) is necessary and sufficient to direct the ectodermal cells toward a neural fate, and that Ca2+ directly controls the expression of neural genes. The mechanism by which the DHP-sensitive Ca2+ channels are activated during neural induction remains unknown. One possible mechanism is via the activation of FGF signalling. Using isolated ectoderm tissue, here we demonstrated that FGF-4 depolarises the membrane of ectodermal cells and induces an increase in [Ca2+]i. This Ca2+ increase can be blocked by SU5402, an FGF receptor inhibitor, and by DHP-sensitive Ca2+ channel antagonists. These inhibitors also block the induction of neural genes. We discuss a possible gating mechanism for the activation of DHP-sensitive Ca2+ channels via the FGF signalling pathway, which involves arachidonic acid and TRPC1 channel activation.
Assuntos
Canais de Cálcio Tipo L/metabolismo , Cálcio/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Transdução de Sinais/fisiologia , Xenopus laevis , Animais , Ácido Araquidônico/metabolismo , Bloqueadores dos Canais de Cálcio/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Embrião não Mamífero/citologia , Embrião não Mamífero/metabolismo , Indução Embrionária , Pirróis/metabolismo , Xenopus laevis/embriologia , Xenopus laevis/genéticaRESUMO
BACKGROUND: Synaptic plasticity associated with an important wave of gene transcription and protein synthesis underlies long-term memory processes. Calcium (Ca2+) plays an important role in a variety of neuronal functions and indirect evidence suggests that it may be involved in synaptic plasticity and in the regulation of gene expression correlated to long-term memory formation. The aim of this study was to determine whether Ca2+ is necessary and sufficient for inducing long-term memory formation. A suitable model to address this question is the Pavlovian appetitive conditioning of the proboscis extension reflex in the honeybee Apis mellifera, in which animals learn to associate an odor with a sucrose reward. RESULTS: By modulating the intracellular Ca2+ concentration ([Ca2+]i) in the brain, we show that: (i) blocking [Ca2+]i increase during multiple-trial conditioning selectively impairs long-term memory performance; (ii) conversely, increasing [Ca2+]i during single-trial conditioning triggers long-term memory formation; and finally, (iii) as was the case for long-term memory produced by multiple-trial conditioning, enhancement of long-term memory performance induced by a [Ca2+]i increase depends on de novo protein synthesis. CONCLUSION: Altogether our data suggest that during olfactory conditioning Ca2+ is both a necessary and a sufficient signal for the formation of protein-dependent long-term memory. Ca2+ therefore appears to act as a switch between short- and long-term storage of learned information.
Assuntos
Abelhas/fisiologia , Sinalização do Cálcio/fisiologia , Memória/fisiologia , Animais , Aprendizagem por Associação/efeitos dos fármacos , Cafeína/farmacologia , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/farmacologia , Quelantes/farmacologia , Condicionamento Clássico/efeitos dos fármacos , Álcoois Graxos/farmacologia , Hexanóis/farmacologia , Memória/efeitos dos fármacos , Memória de Curto Prazo/efeitos dos fármacos , Modelos Animais , Odorantes , Condutos Olfatórios/fisiologia , Biossíntese de Proteínas , Olfato/fisiologiaRESUMO
Neural induction is a developmental process that allows cells from the ectoderm (the target tissue) to acquire a neural fate in response to signals coming from a specific adjacent embryonic region, the dorsal mesoderm (the inducing tissue). This process described in 1924 in amphibian embryos has not received a molecular explanation until the mid-1990s. Most of the work on neural induction has been carried out in amphibians. At these times, although the role played by the membrane of the target tissue had been suggested, no definitive work had been performed on the transduction of the neuralizing signal. Between 1990 and 2019 our aim was to decipher this transduction. We have underlined the necessary and sufficient role played by calcium signaling to induce ectoderm cells towards a neural fate from the activation of calcium channels to the direct transcription of early neural genes by calcium.
TITLE: La saga de l'induction neurale : presque un siècle de recherche. ABSTRACT: La formation du système nerveux débute par l'induction neurale, un processus qui permet aux cellules de l'ectoderme (tissu cible) d'acquérir un destin neural en réponse à des signaux provenant du mésoderme dorsal (tissu inducteur). Ce processus, décrit en 1924 sur l'amphibien, n'a reçu une explication moléculaire qu'au milieu des années 1990. Pendant cette période, plusieurs auteurs se sont intéressés au rôle joué par la membrane du tissu cible mais peu de travaux décisifs ont décrit la transduction du signal neuralisant. Entre 1990 et 2019, nous avons disséqué la transduction du signal neuralisant, un sujet très peu abordé alors. Nous avons souligné le rôle nécessaire et suffisant du calcium pour orienter les cellules de l'ectoderme vers un destin neural et établi la cascade moléculaire allant de l'activation de canaux membranaires à la transcription de gènes.
Assuntos
Embriologia/história , Indução Embrionária/fisiologia , Sistema Nervoso/embriologia , Neurogênese/fisiologia , Anfíbios/embriologia , Anfíbios/metabolismo , Animais , Pesquisa Biomédica/história , Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Embrião não Mamífero , História do Século XIX , História do Século XX , História do Século XXI , HumanosRESUMO
In amphibians, the inhibition of bone morphogenetic protein (BMP) in the dorsal ectoderm has been proposed to be responsible for the first step of neural specification, called neural induction. We previously demonstrated that in Xenopus laevis embryos, the BMP signalling antagonist, noggin, triggers an influx of Ca2+ through voltage-dependent L-type Ca2+ channels (LTCCs), mainly via CaV1.2, and we showed that this influx constitutes a necessary and sufficient signal for triggering the expression of neural genes. However, the mechanism linking the inhibition of BMP signalling with the activation of LTCCs remained unknown. Here, we demonstrate that the transient receptor potential canonical subfamily member 1, (Trpc1), is an intermediate between BMP receptor type II (BMPRII) and the CaV1.2 channel. We show that noggin induces a physical interaction between BMPRII and Trpc1 channels. This interaction leads to the activation of Trpc1 channels and to an influx of cations, which depolarizes the plasma membrane up to a threshold sufficient to activate Cav1.2. Together, our results demonstrate for the first time that during neural induction, Ca2+ entry through the CaV1.2 channel results from the noggin-induced interaction between Trpc1 and BMPRII.
Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Sinalização do Cálcio , Embrião não Mamífero/embriologia , Neurogênese , Canais de Cátion TRPC/metabolismo , Proteínas de Xenopus/metabolismo , Animais , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/genética , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/metabolismo , Proteínas Morfogenéticas Ósseas/genética , Membrana Celular/genética , Membrana Celular/metabolismo , Potenciais da Membrana , Canais de Cátion TRPC/genética , Proteínas de Xenopus/genética , Xenopus laevisRESUMO
Modification of proteins by methylation has emerged as a key regulatory mechanism in many cellular processes, including gene control. Eighty to ninety percent of the arginine methylation in the cell is performed by the protein arginine methyl transferase PRMT1. ILF3, a protein involved in gene regulation at several levels, has been shown to be a substrate and regulator of PRMT1 in mammals. Here we show that the Xenopus orthologue of ILF3 (Xilf3) is methylated in vivo, and, at least in vitro, this methylation is carried out by Xprmt1b. The in vitro methylation of Xilf3 inhibits its ability to bind to DNA while leaving RNA binding activity unaltered. Consistent with these activities having a role in vivo, the DNA binding activity of the Xilf3-containing CBTF complex and the transcription of its target gene, Xgata2, are both decreased by overexpression of Xprmt1b in embryos. However, in contrast to other RNA binding proteins, a changing degree of methylation does not alter the subcellular localization of Xilf3. Several other proteins involved in gene regulation can bind both RNA and DNA; these data demonstrate a mechanism by which such binding activities may be controlled independently.
Assuntos
DNA/metabolismo , Metiltransferases/metabolismo , Proteínas do Fator Nuclear 90/metabolismo , Proteínas de Ligação a RNA/metabolismo , RNA/metabolismo , Proteínas de Xenopus/metabolismo , Sequência de Aminoácidos , Animais , Células Cultivadas , DNA/genética , Metilação de DNA , Metiltransferases/genética , Dados de Sequência Molecular , Proteínas do Fator Nuclear 90/genética , Ligação Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , RNA/genética , Xenopus , Proteínas de Xenopus/genéticaRESUMO
Glioblastomas (GBMs) are the most aggressive and lethal primary astrocytic tumors in adults, with very poor prognosis. Recurrence in GBM is attributed to glioblastoma stem-like cells (GSLCs). The behavior of the tumor, including proliferation, progression, invasion, and significant resistance to therapies, is a consequence of the self-renewing properties of the GSLCs, and their high resistance to chemotherapies have been attributed to their capacity to enter quiescence. Thus, targeting GSLCs may constitute one of the possible therapeutic challenges to significantly improve anti-cancer treatment regimens for GBM. Ca2+ signaling is an important regulator of tumorigenesis in GBM, and the transition from proliferation to quiescence involves the modification of the kinetics of Ca2+ influx through store-operated channels due to an increased capacity of the mitochondria of quiescent GSLC to capture Ca2+. Therefore, the identification of new therapeutic targets requires the analysis of the calcium-regulated elements at transcriptional levels. In this review, we focus onto the direct regulation of gene expression by KCNIP proteins (KCNIP1-4). These proteins constitute the class E of Ca2+ sensor family with four EF-hand Ca2+-binding motifs and control gene transcription directly by binding, via a Ca2+-dependent mechanism, to specific DNA sites on target genes, called downstream regulatory element (DRE). The presence of putative DRE sites on genes associated with unfavorable outcome for GBM patients suggests that KCNIP proteins may contribute to the alteration of the expression of these prognosis genes. Indeed, in GBM, KCNIP2 expression appears to be significantly linked to the overall survival of patients. In this review, we summarize the current knowledge regarding the quiescent GSLCs with respect to Ca2+ signaling and discuss how Ca2+ via KCNIP proteins may affect prognosis genes expression in GBM. This original mechanism may constitute the basis of the development of new therapeutic strategies.
RESUMO
Quiescence is a reversible cell-cycle arrest which allows cancer stem-like cells to evade killing following therapies. Here, we show that proliferating glioblastoma stem-like cells (GSLCs) can be induced and maintained in a quiescent state by lowering the extracellular pH. Through RNAseq analysis we identified Ca2+ signalling genes differentially expressed between proliferating and quiescent GSLCs. Using the bioluminescent Ca2+ reporter EGFP-aequorin we observed that the changes in Ca2+ homeostasis occurring during the switch from proliferation to quiescence are controlled through store-operated channels (SOC) since inhibition of SOC drives proliferating GSLCs to quiescence. We showed that this switch is characterized by an increased capacity of GSLCs' mitochondria to capture Ca2+ and by a dramatic and reversible change of mitochondrial morphology from a tubular to a donut shape. Our data suggest that the remodelling of the Ca2+ homeostasis and the reshaping of mitochondria might favours quiescent GSLCs' survival and their aggressiveness in glioblastoma.
Assuntos
Sinalização do Cálcio/fisiologia , Glioblastoma/metabolismo , Mitocôndrias/metabolismo , Células-Tronco Neoplásicas/citologia , Adulto , Apoptose/fisiologia , Divisão Celular/fisiologia , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Sobrevivência Celular/fisiologia , Humanos , Transdução de Sinais/fisiologia , Adulto JovemRESUMO
Development of the vertebrate embryonic nervous system is characterized by a cascade of signalling events. In Xenopus, the initial step in this cascade results from signals emanating from the dorsal mesoderm that divert the fate of the ectoderm from an epidermal to a neural lineage. These signals include extracellular antagonists of the bone morphogenetic protein (BMP). Experiments performed with isolated ectoderm suggest that epidermis is induced by BMP, whereas neural fates arise by default following BMP inhibition; however, we show that this mechanism is not sufficient for neural determination. Ca2+ imaging of intact Xenopus embryos reveals patterns of Ca2+ transients in the dorsal ectoderm but not in the ventral ectoderm. These increases in intracellular calcium concentration ([Ca2+](i)), which occur via the activation of dihydropyridine (DHP)-sensitive Ca2+ channels, are necessary and sufficient to orientate the ectodermal cells toward a neural fate. On the one hand, the treatments that antagonize the increase in [Ca2+](i), inhibit neuralization, while on the other hand, an artificial increase in [Ca2+](i), whatever its origin, neuralizes the ectoderm. Using these properties, we have constructed a subtractive cDNA library between untreated ectoderm and caffeine-treated ectoderm. The caffeine stimulates an increase in [Ca2+](i) and thus orientates the cells towards the neural pathway. We have identified early Ca2+ target genes expressed in neural territories. One of these genes, an arginine methyl transferase, controls the expression of the early proneural gene, Zic3. Here, we discuss an alternative model where Ca2+ plays a central regulatory role in early neurogenesis. This model integrates the activation of a Ca2+ -dependent signalling pathway due to an influx of Ca2+ through DHP-Ca2+ channels. While Ca2+ is required for neural determination, epidermal determination occurs when Ca2+ -dependent signalling pathways are inactive.
Assuntos
Sinalização do Cálcio , Cálcio/fisiologia , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Sistema Nervoso/embriologia , Xenopus laevis/embriologia , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/genética , Canais de Cálcio/fisiologia , Xenopus laevis/genéticaRESUMO
During embryogenesis, a rise in intracellular Ca(2+) is known to be a widespread trigger for directing stem cells towards a specific tissue fate, but the precise Ca(2+) signalling mechanisms involved in achieving these pleiotropic effects are still poorly understood. In this review, we compare the Ca(2+) signalling events that appear to be one of the first steps in initiating and regulating both neural determination (neural induction) and kidney development (nephrogenesis). We have highlighted the necessary and sufficient role played by Ca(2+) influx and by Ca(2+) transients in the determination and differentiation of pools of neural or renal precursors. We have identified new Ca(2+) target genes involved in neural induction and we showed that the same Ca(2+) early target genes studied are not restricted to neural tissue but are also present in other tissues, principally in the pronephros. In this review, we also described a mechanism whereby the transcriptional control of gene expression during neurogenesis and nephrogenesis might be directly controlled by Ca(2+) signalling. This mechanism involves members of the Kcnip family such that a change in their binding properties to specific DNA sites is a result of Ca(2+) binding to EF-hand motifs. The different functions of Ca(2+) signalling during these two events illustrate the versatility of Ca(2+) as a second messenger.
Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Rim/citologia , Rim/metabolismo , Neurogênese , Células-Tronco/citologia , Células-Tronco/metabolismo , Animais , Humanos , Rim/embriologia , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismoRESUMO
The calcium (Ca(2+)) signaling pathways have crucial roles in development from fertilization through differentiation to organogenesis. In the nervous system, Ca(2+) signals are important regulators for various neuronal functions, including formation and maturation of neuronal circuits and long-term memory. However, Ca(2+) signals are also involved in the earliest steps of neurogenesis including neural induction, differentiation of neural progenitors into neurons, and the neuro-glial switch. This review examines when and how Ca(2+) signals are generated during each of these steps with examples taken from in vivo studies in vertebrate embryos and from in vitro assays using embryonic and neural stem cells (NSCs). During the early phases of neurogenesis few investigations have been performed to study the downstream targets of Ca(2+) which posses EF-hand in their structure. This opens an entire field of research. We also discuss the highly specific nature of the Ca(2+) signaling pathway and its interaction with the other signaling pathways involved in early neural development.
Assuntos
Sinalização do Cálcio , Cálcio/fisiologia , Ectoderma/enzimologia , Metiltransferases/biossíntese , Proteínas de Xenopus/biossíntese , Animais , Blástula/enzimologia , Proteína Morfogenética Óssea 4 , Receptores de Proteínas Morfogenéticas Ósseas/fisiologia , Proteínas Morfogenéticas Ósseas/fisiologia , Cafeína/farmacologia , Proteínas de Transporte/fisiologia , Diferenciação Celular , Quelantes/farmacologia , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Indução Enzimática/efeitos dos fármacos , Gástrula/enzimologia , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Metiltransferases/genética , Sistema Nervoso/embriologia , Técnicas de Cultura de Órgãos , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Proteínas de Xenopus/genética , Xenopus laevis/embriologiaRESUMO
The calcium (Ca(2+)) signaling pathways have crucial roles in development from fertilization through differentiation to organogenesis. In the nervous system, Ca(2+) signals are important regulators for various neuronal functions, including formation and maturation of neuronal circuits and long-term memory. However, Ca(2+) signals are mainly involved in the earliest steps of nervous system development including neural induction, differentiation of neural progenitors into neurons, and the neuro-glial switch. This review examines when and how Ca(2+) signals are generated during each of these steps with examples taken from in vivo studies in vertebrate embryos and from in vitro assays using embryonic and neural stem cells. Also discussed is the highly specific nature of the Ca(2+) signaling pathway and its interaction with the other signaling pathways involved in early neural development.
Assuntos
Sinalização do Cálcio , Sistema Nervoso/embriologia , Animais , Proliferação de Células , Células-Tronco Embrionárias/metabolismo , Células-Tronco Embrionárias/fisiologia , Gastrulação , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Sistema Nervoso/citologia , Sistema Nervoso/metabolismo , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/fisiologia , NeurogêneseRESUMO
In amphibian embryos, calcium (Ca(2+)) signalling is a necessary and sufficient event to induce neural fate. Transient elevations of [Ca(2+)]i are recorded in neural tissue precursor cells in whole embryos during gastrulation. Using a subtractive cDNA library between control ectoderm (animal caps) and ectoderm induced toward a neural fate by Ca(2+) release, we have isolated several Ca(2+)-induced target genes. Among the isolated genes, Xp54nrb encodes a protein which exhibits the RRM domains characteristic of RNA binding proteins, and is implicated in pre-mRNA splicing steps. Here we show that the Xp54nrb transcripts are expressed throughout early developmental stages, specifically in the neural and sensorial territories and that Xp54nrb could be involved in anterior neural patterning.