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1.
J Neurochem ; 154(6): 618-634, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32068252

RESUMO

The SynGAP protein is a major regulator of synapse biology and neural circuit function. Genetic variants linked to epilepsy and intellectual disability disrupt synaptic function and neural excitability. SynGAP has been involved in multiple signaling pathways and can regulate small GTPases with very different roles. Yet, the molecular bases behind this pleiotropy are poorly understood. We hypothesize that different SynGAP isoforms will mediate different sets of functions and that deciphering their spatio-temporal expression and subcellular localization will accelerate understanding their multiple functions. Using isoform-specific antibodies recognizing SynGAP in mouse and human samples we found distinctive developmental expression patterns for all SynGAP isoforms in five mouse brain areas. Particularly noticeable was the delayed expression of SynGAP-α1 isoforms, which directly bind to postsynaptic density-95, in cortex and hippocampus during the first 2 weeks of postnatal development. Suggesting that during this period other isoforms would have a more prominent role. Furthermore, we observed subcellular localization differences between isoforms, particularly throughout postnatal development. Consistent with previous reports, SynGAP was enriched in the postsynaptic density in the mature forebrain. However, SynGAP was predominantly found in non-synaptic locations in a period of early postnatal development highly sensitive to SynGAP levels. While, α1 isoforms were always found enriched in the postsynaptic density, α2 isoforms changed from a non-synaptic to a mostly postsynaptic density localization with age and ß isoforms were always found enriched in non-synaptic locations. The differential expression and subcellular distribution of SynGAP isoforms may contribute to isoform-specific regulation of small GTPases, explaining SynGAP pleiotropy.


Assuntos
Encéfalo/crescimento & desenvolvimento , Proteínas Ativadoras de ras GTPase/genética , Animais , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Simulação por Computador , Regulação da Expressão Gênica no Desenvolvimento/genética , Hipocampo/crescimento & desenvolvimento , Hipocampo/metabolismo , Humanos , Isomerismo , Camundongos , Camundongos Endogâmicos C57BL , Isoformas de Proteínas/biossíntese , Isoformas de Proteínas/genética , Proteômica , Frações Subcelulares/metabolismo , Proteínas Ativadoras de ras GTPase/biossíntese
2.
Chromosoma ; 125(2): 337-51, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26525972

RESUMO

Telomeres protect against genome instability and participate in chromosomal movements during gametogenesis, especially in meiosis. Thus, maintaining telomere structure and telomeric length is essential to both cell integrity and the production of germ cells. As a result, alteration of telomere homeostasis in the germ line may result in the generation of aneuploid gametes or gametogenesis disruption, triggering fertility problems. In this work, we provide an overview on fundamental aspects of the literature regarding the organization of telomeres in mammalian germ cells, paying special attention to telomere structure and function, as well as the maintenance of telomeric length during gametogenesis. Moreover, we discuss the different roles recently described for telomerase and TERRA in maintaining telomere functionality. Finally, we review how new findings in the field of reproductive biology underscore the role of telomere homeostasis as a potential biomarker for infertility. Overall, we anticipate that the study of telomere stability and equilibrium will contribute to improve diagnoses of patients; assess the risk of infertility in the offspring; and in turn, find new treatments.


Assuntos
Células Germinativas/metabolismo , Mamíferos/genética , Telômero/genética , Animais , Células Germinativas/citologia , Homeostase , Humanos , Mamíferos/metabolismo , Telomerase/genética , Telomerase/metabolismo , Telômero/metabolismo
3.
Biol Reprod ; 90(5): 103, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24719256

RESUMO

Telomeres are ribonucleoprotein structures at the end of chromosomes composed of telomeric DNA, specific-binding proteins, and noncoding RNA (TERRA). Despite their importance in preventing chromosome instability, little is known about the cross talk between these three elements during the formation of the germ line. Here, we provide evidence that both TERRA and the telomerase enzymatic subunit (TERT) are components of telomeres in mammalian germ cells. We found that TERRA colocalizes with telomeres during mammalian meiosis and that its expression progressively increases during spermatogenesis until the beginning of spermiogenesis. While both TERRA levels and distribution would be regulated in a gender-specific manner, telomere-TERT colocalization appears to be regulated based on species-specific characteristics of the telomeric structure. Moreover, we found that TERT localization at telomeres is maintained throughout spermatogenesis as a structural component without affecting telomere elongation. Our results represent the first evidence of colocalization between telomerase and telomeres during mammalian gametogenesis.


Assuntos
Gametogênese/genética , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Meiose/fisiologia , RNA não Traduzido/metabolismo , Telomerase/metabolismo , Telômero/metabolismo , Animais , Feminino , Citometria de Fluxo , Células HeLa , Humanos , Hibridização in Situ Fluorescente , Masculino , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , RNA/química , RNA/genética , RNA não Traduzido/genética , Reação em Cadeia da Polimerase em Tempo Real , Telomerase/genética , Telômero/enzimologia , Telômero/genética
4.
Hum Reprod ; 28(2): 414-22, 2013 02.
Artigo em Inglês | MEDLINE | ID: mdl-23049077

RESUMO

STUDY QUESTION: What is the distribution of telomeric repeat-containing RNA (TERRA) and of telomerase in human fetal oocytes? SUMMARY ANSWER: TERRA forms discrete foci at telomeres of human fetal oocytes and it co-localizes with both the shelterin component telomeric repeat-binding factor 2 (TRF2) and the catalytic subunit of human telomerase at the telomeres of meiotic chromosomes. WHAT IS KNOWN ALREADY: TERRA is a structural element of the telomeric chromatin that has been described in somatic cells of many different eukaryote species. The telomerase enzyme is inactive in adult somatic cells but is active in germ cells, stem cells and in the majority of tumors; however, its distribution in oocytes is still unknown. STUDY DESIGN, SIZE, DURATION: For this study, ovarian samples from four euploid fetuses of 22 gestational weeks were used. These samples were obtained with the consent of the parents and of the Ethics Committee of Hospital de la Vall d'Hebron. PARTICIPANTS/MATERIALS, SETTING, METHODS: We analyzed the distribution of TERRA and telomerase in cells derived from human fetal ovaries. The co-localization of TERRA, telomerase and telomeres was performed by optimizing a combination of immunofluorescence (IF) and RNA-fluorescent in situ hybridization (RNA-FISH) techniques. The synaptonemal complex protein 3 (SYCP3), TRF2 and protein component of telomerase [telomerase reverse transcriptase (TERT)] were detected by IF, whereas TERRA was revealed by RNA-FISH using a (CCCTAA)(3) oligonucleotide. SYCP3 signals allowed us to identify oocytes that had entered meiosis and classify them into the different stages of prophase I, whereas TRF2 indicated the telomeric regions of chromosomes. MAIN RESULTS AND THE ROLE OF CHANCE: We show for the first time the presence of TERRA and the intracellular distribution of telomerase in human fetal ovarian cells. TERRA is present, forming discrete foci, in 75% of the ovarian tissue cells and most of TERRA molecules (≈ 83%) are at telomeres (TRF2 co-localization). TERRA levels are higher in oocytes than in ovarian tissue cells (P = 0.00), and do not change along the progression of the prophase I stage (P = 0.37). TERRA is present on ≈ 23% of the telomeres in all cell types derived from human fetal ovaries. Moreover, ≈ 22% of TERRA foci co-localize with the protein component of telomerase (TERT). LIMITATIONS, REASONS FOR CAUTION: We present a descriptive/qualitative study of TERRA in human fetal ovarian tissue. Given the difficult access and manipulation of fetal samples, the number of fetal ovaries used in this study was limited. WIDER IMPLICATIONS OF THE FINDINGS: This is the first report on TERRA expression in oocytes from human fetal ovaries. The presence of TERRA at the telomeres of oocytes from the leptotene to pachytene stages and its co-localization with the telomerase protein component suggests that this RNA might participate in the maintenance of the telomere structure, at least through the processes that take place during the female meiotic prophase I. Since telomeres in oocytes have been mainly studied regarding the bouquet structure, our results introduce a new viewpoint of the telomeric structure during meiosis.


Assuntos
Feto/citologia , Oócitos/enzimologia , RNA/metabolismo , Telomerase/metabolismo , Células Cultivadas , Feminino , Feto/enzimologia , Células HeLa , Humanos
5.
Cell Rep ; 35(10): 109229, 2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34107264

RESUMO

Hippocampal sclerosis, the major neuropathological hallmark of temporal lobe epilepsy, is characterized by different patterns of neuronal loss. The mechanisms of cell-type-specific vulnerability and their progression and histopathological classification remain controversial. Using single-cell electrophysiology in vivo and immediate-early gene expression, we reveal that superficial CA1 pyramidal neurons are overactive in epileptic rodents. Bulk tissue and single-nucleus expression profiling disclose sublayer-specific transcriptomic signatures and robust microglial pro-inflammatory responses. Transcripts regulating neuronal processes such as voltage channels, synaptic signaling, and cell adhesion are deregulated differently by epilepsy across sublayers, whereas neurodegenerative signatures primarily involve superficial cells. Pseudotime analysis of gene expression in single nuclei and in situ validation reveal separated trajectories from health to epilepsy across cell types and identify a subset of superficial cells undergoing a later stage in neurodegeneration. Our findings indicate that sublayer- and cell-type-specific changes associated with selective CA1 neuronal damage contribute to progression of hippocampal sclerosis.


Assuntos
Epilepsia/patologia , Hipocampo/metabolismo , Doenças Neurodegenerativas/fisiopatologia , Neurônios/patologia , Esclerose/genética , Animais , Humanos , Camundongos
6.
Neuron ; 103(2): 217-234.e4, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31171447

RESUMO

Synapses are fundamental information-processing units of the brain, and synaptic dysregulation is central to many brain disorders ("synaptopathies"). However, systematic annotation of synaptic genes and ontology of synaptic processes are currently lacking. We established SynGO, an interactive knowledge base that accumulates available research about synapse biology using Gene Ontology (GO) annotations to novel ontology terms: 87 synaptic locations and 179 synaptic processes. SynGO annotations are exclusively based on published, expert-curated evidence. Using 2,922 annotations for 1,112 genes, we show that synaptic genes are exceptionally well conserved and less tolerant to mutations than other genes. Many SynGO terms are significantly overrepresented among gene variations associated with intelligence, educational attainment, ADHD, autism, and bipolar disorder and among de novo variants associated with neurodevelopmental disorders, including schizophrenia. SynGO is a public, universal reference for synapse research and an online analysis platform for interpretation of large-scale -omics data (https://syngoportal.org and http://geneontology.org).


Assuntos
Encéfalo/citologia , Ontologia Genética , Proteômica , Software , Sinapses/fisiologia , Animais , Encéfalo/fisiologia , Bases de Dados Genéticas , Humanos , Bases de Conhecimento , Potenciais Sinápticos/fisiologia , Sinaptossomos
7.
Prog Neuropsychopharmacol Biol Psychiatry ; 84(Pt B): 353-361, 2018 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-28941771

RESUMO

Synapses are centrally involved in many brain disorders, particularly in psychiatric and neurodevelopmental ones. However, our current understanding of the proteomic alterations affecting synaptic performance in the majority of mental illnesses is limited. As a result, novel pharmacotherapies with improved neurological efficacy have been scarce over the past decades. The main goal of synaptic proteomics in the context of mental illnesses is to identify dysregulated molecular mechanisms underlying these conditions. Here we reviewed and performed a meta-analysis of previous neuroproteomic research to identify proteins that may be consistently dysregulated in one or several mental disorders. Notably, we found very few proteins reproducibly altered among independent experiments for any given condition or between conditions, indicating that we are still far from identifying key pathophysiological mechanisms of mental illness. We suggest that future research in the field will require higher levels of standardization and larger-scale experiments to address the challenge posed by biological and methodological variability. We strongly believe that more resources should be placed in this field as the need to identify the molecular roots of mental illnesses is highly pressing.


Assuntos
Transtornos Mentais , Proteômica , Sinapses/metabolismo , Animais , Humanos , Transtornos Mentais/genética , Transtornos Mentais/metabolismo , Transtornos Mentais/patologia , Metanálise como Assunto , Sinapses/patologia
8.
Elife ; 72018 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-30465522

RESUMO

Glutamate receptors are divided in two unrelated families: ionotropic (iGluR), driving synaptic transmission, and metabotropic (mGluR), which modulate synaptic strength. The present classification of GluRs is based on vertebrate proteins and has remained unchanged for over two decades. Here we report an exhaustive phylogenetic study of GluRs in metazoans. Importantly, we demonstrate that GluRs have followed different evolutionary histories in separated animal lineages. Our analysis reveals that the present organization of iGluRs into six classes does not capture the full complexity of their evolution. Instead, we propose an organization into four subfamilies and ten classes, four of which have never been previously described. Furthermore, we report a sister class to mGluR classes I-III, class IV. We show that many unreported proteins are expressed in the nervous system, and that new Epsilon receptors form functional ligand-gated ion channels. We propose an updated classification of glutamate receptors that includes our findings.


Assuntos
Evolução Molecular , Variação Genética , Receptores Ionotrópicos de Glutamato/genética , Receptores de Glutamato Metabotrópico/genética , Sequência de Aminoácidos , Animais , Teorema de Bayes , Sítios de Ligação/genética , Células HEK293 , Humanos , Modelos Moleculares , Filogenia , Domínios Proteicos , Receptores Ionotrópicos de Glutamato/química , Receptores Ionotrópicos de Glutamato/classificação , Receptores de Glutamato Metabotrópico/química , Receptores de Glutamato Metabotrópico/classificação , Homologia de Sequência de Aminoácidos
9.
Nat Commun ; 8: 14613, 2017 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-28252024

RESUMO

The proteome of human brain synapses is highly complex and is mutated in over 130 diseases. This complexity arose from two whole-genome duplications early in the vertebrate lineage. Zebrafish are used in modelling human diseases; however, its synapse proteome is uncharacterized, and whether the teleost-specific genome duplication (TSGD) influenced complexity is unknown. We report the characterization of the proteomes and ultrastructure of central synapses in zebrafish and analyse the importance of the TSGD. While the TSGD increases overall synapse proteome complexity, the postsynaptic density (PSD) proteome of zebrafish has lower complexity than mammals. A highly conserved set of ∼1,000 proteins is shared across vertebrates. PSD ultrastructural features are also conserved. Lineage-specific proteome differences indicate that vertebrate species evolved distinct synapse types and functions. The data sets are a resource for a wide range of studies and have important implications for the use of zebrafish in modelling human synaptic diseases.


Assuntos
Encéfalo/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteoma/metabolismo , Proteoma/ultraestrutura , Sinapses/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Encéfalo/ultraestrutura , Feminino , Duplicação Gênica , Genoma , Masculino , Camundongos , Microscopia Eletrônica de Transmissão , Modelos Biológicos , Proteínas do Tecido Nervoso/genética , Densidade Pós-Sináptica/metabolismo , Proteoma/genética , Especificidade da Espécie , Sinapses/ultraestrutura , Sinaptossomos/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/genética
10.
Fertil Steril ; 102(3): 728-738.e1, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24996497

RESUMO

OBJECTIVE: To study whether the telomere structure of germ cells from idiopathic infertile men is altered and if this impairment is influenced by meiotic recombination and telomere length. DESIGN: We performed a detailed analysis of both telomeric repeat-containing RNA (TERRA) and telomerase distribution in testis cell spreads by combining immunofluorescence and RNA fluorescent in situ hybridization. In addition we analyzed meiotic recombination between homologous chromosomes by immunofluorescence and telomere length by quantitative fluorescent in situ hybridization. SETTING: University. PATIENT(S): Men consulting for fertility problems. INTERVENTION(S): Unilateral testicular biopsies. MAIN OUTCOME MEASURE(S): We observed that TERRA levels and its nuclear distribution were compromised in infertile patients. In addition, the presence of the protein component of telomerase at telomeres decreased in the affected patients. However, neither telomerase-TERRA association nor telomere length was altered in spermatocytes I of infertile samples compared with control individuals. In addition, we observed that meiotic recombination was reduced in infertile individuals. RESULT(S): Telomere homeostasis is impaired in infertile patients, and this was translated into a decrease in TERRA levels together with an alteration of the TERRA-protein component of telomerase telomeric association in primary spermatocytes. CONCLUSION(S): This study demonstrates for the first time that telomere structure and homeostasis in germ cells is compromised in infertile individuals. In the light of our results we propose that the analysis of telomeric structure (i.e., TERRA levels and telomere association with TERRA and telomerase) would provide new tools for our understanding of the origin of human infertility.


Assuntos
Infertilidade Masculina/genética , Espermatócitos/metabolismo , Homeostase do Telômero , Estudos de Casos e Controles , Núcleo Celular/genética , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Células HeLa , Humanos , Masculino , Recombinação Genética , Telomerase/metabolismo , Telômero/metabolismo , Fatores de Transcrição/metabolismo
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