RESUMO
The ability of neurons to rapidly remodel their synaptic structure and strength in response to neuronal activity is highly conserved across species and crucial for complex brain functions. However, mechanisms required to elicit and coordinate the acute, activity-dependent structural changes across synapses are not well understood, as neurodevelopment and structural plasticity are tightly linked. Here, using an RNAi screen in Drosophila against genes affecting nervous system functions in humans, we uncouple cellular processes important for synaptic plasticity and synapse development. We find mutations associated with neurodegenerative and mental health disorders are 2-times more likely to affect activity-induced synaptic remodeling than synapse development. We report that while both synapse development and activity-induced synaptic remodeling at the fly NMJ require macroautophagy (hereafter referred to as autophagy), bifurcation in the autophagy pathway differentially impacts development and synaptic plasticity. We demonstrate that neuronal activity enhances autophagy activation but diminishes degradative autophagy, thereby driving the pathway towards autophagy-based secretion. Presynaptic knockdown of Snap29, Sec22, or Rab8, proteins implicated in the secretory autophagy pathway, is sufficient to abolish activity-induced synaptic remodeling. This study uncovers secretory autophagy as a transsynaptic signaling mechanism modulating synaptic plasticity.
Assuntos
Proteínas de Drosophila , Junção Neuromuscular , Animais , Humanos , Junção Neuromuscular/metabolismo , Sinapses/metabolismo , Drosophila/fisiologia , Neurônios/metabolismo , Autofagia/genética , Plasticidade Neuronal/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Transmissão Sináptica/fisiologia , GTP Fosfo-Hidrolases/metabolismoRESUMO
BACKGROUND: Many pregnant persons in the United States are receiving messenger RNA (mRNA) coronavirus disease 2019 (Covid-19) vaccines, but data are limited on their safety in pregnancy. METHODS: From December 14, 2020, to February 28, 2021, we used data from the "v-safe after vaccination health checker" surveillance system, the v-safe pregnancy registry, and the Vaccine Adverse Event Reporting System (VAERS) to characterize the initial safety of mRNA Covid-19 vaccines in pregnant persons. RESULTS: A total of 35,691 v-safe participants 16 to 54 years of age identified as pregnant. Injection-site pain was reported more frequently among pregnant persons than among nonpregnant women, whereas headache, myalgia, chills, and fever were reported less frequently. Among 3958 participants enrolled in the v-safe pregnancy registry, 827 had a completed pregnancy, of which 115 (13.9%) resulted in a pregnancy loss and 712 (86.1%) resulted in a live birth (mostly among participants with vaccination in the third trimester). Adverse neonatal outcomes included preterm birth (in 9.4%) and small size for gestational age (in 3.2%); no neonatal deaths were reported. Although not directly comparable, calculated proportions of adverse pregnancy and neonatal outcomes in persons vaccinated against Covid-19 who had a completed pregnancy were similar to incidences reported in studies involving pregnant women that were conducted before the Covid-19 pandemic. Among 221 pregnancy-related adverse events reported to the VAERS, the most frequently reported event was spontaneous abortion (46 cases). CONCLUSIONS: Preliminary findings did not show obvious safety signals among pregnant persons who received mRNA Covid-19 vaccines. However, more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform maternal, pregnancy, and infant outcomes.
Assuntos
Vacinas contra COVID-19/efeitos adversos , Gravidez , Aborto Espontâneo/epidemiologia , Adolescente , Adulto , Sistemas de Notificação de Reações Adversas a Medicamentos , Vacinas contra COVID-19/imunologia , Feminino , Humanos , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Pessoa de Meia-Idade , Nascimento Prematuro/epidemiologia , Vigilância em Saúde Pública/métodos , Sistema de Registros , Estados Unidos/epidemiologia , Vacinas Sintéticas/efeitos adversos , Adulto Jovem , Vacinas de mRNARESUMO
Whether epigenetic factors such as DNA methylation and microRNAs interact to control adult hippocampal neurogenesis is not fully understood. Here, we show that Down syndrome critical region 1 (DSCR1) protein plays a key role in adult hippocampal neurogenesis by modulating two epigenetic factors: TET1 and miR-124. We find that DSCR1 mutant mice have impaired adult hippocampal neurogenesis. DSCR1 binds to TET1 introns to regulate splicing of TET1, thereby modulating TET1 level. Furthermore, TET1 controls the demethylation of the miRNA-124 promoter to modulate miR-124 expression. Correcting the level of TET1 in DSCR1 knockout mice is sufficient to prevent defective adult neurogenesis. Importantly, restoring DSCR1 level in a Down syndrome mouse model effectively rescued adult neurogenesis and learning and memory deficits. Our study reveals that DSCR1 plays a critical upstream role in epigenetic regulation of adult neurogenesis and provides insights into potential therapeutic strategy for treating cognitive defects in Down syndrome.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Síndrome de Down/genética , Hipocampo/citologia , MicroRNAs/genética , Oxigenases de Função Mista/genética , Proteínas Musculares/metabolismo , Proteínas Proto-Oncogênicas/genética , Splicing de RNA , Animais , Células Cultivadas , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Síndrome de Down/metabolismo , Epigênese Genética , Técnicas de Silenciamento de Genes , Hipocampo/metabolismo , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Proteínas Musculares/genética , Mutação , Neurogênese , Regiões Promotoras GenéticasRESUMO
BACKGROUND: The Global Nutrition Target of reducing low birthweight (LBW) by ≥30% between 2012 and 2025 has led to renewed interest in producing accurate, population-based, national LBW estimates. Low- and middle-income countries rely on household surveys for birthweight data. These data are frequently incomplete and exhibit strong "heaping." Standard survey adjustment methods produce estimates with residual bias. The global database used to report against the LBW Global Nutrition Target adjusts survey data using a new MINORMIX (multiple imputation followed by normal mixture) approach: 1) multiple imputation to address missing birthweights, followed by 2) use of a 2-component normal mixture model to account for heaping of birthweights. OBJECTIVES: To evaluate the performance of the MINORMIX birthweight adjustment approach and alternative methods against gold-standard measured birthweights in rural Nepal. METHODS: As part of a community-randomized trial in rural Nepal, we measured "gold-standard" birthweights at birth and returned 1-24 mo later to collect maternally reported birthweights using standard survey methods. We compared estimates of LBW from maternally reported data derived using: 1) the new MINORMAX approach; 2) the previously used Blanc-Wardlaw adjustment; or 3) no adjustment for missingness or heaping against our gold standard. We also assessed the independent contribution of multiple imputation and curve fitting to LBW adjustment. RESULTS: Our gold standard found 27.7% of newborns were LBW. The unadjusted LBW estimate based on maternal report with simulated missing birthweights was 14.5% (95% CI: 11.6, 18.0%). Application of the Blanc-Wardlaw adjustment increased the LBW estimate to 20.6%. The MINORMIX approach produced an estimate of 26.4% (95% CI: 23.5, 29.3%) LBW, closest to and with bounds encompassing the measured point estimate. CONCLUSIONS: In a rural Nepal validation dataset, the MINORMIX method generated a more accurate LBW estimate than the previously applied adjustment method. This supports the use of the MINORMIX method to produce estimates for tracking the LBW Global Nutrition Target.
Assuntos
Recém-Nascido de Baixo Peso , População Rural , Peso ao Nascer , Humanos , Recém-Nascido , Nepal/epidemiologia , PrevalênciaRESUMO
Highly developed meningeal lymphatics remove waste products from the brain. Disruption of meningeal lymphatic vessels in a mouse model of amyloid pathology (5XFAD) accelerates the accumulation of amyloid plaques in the meninges and brain, and causes learning and memory deficits, suggesting that clearance of toxic wastes by lymphatic vessels plays a key role in neurodegenerative diseases. Here, we discovered that DSCR1 (Down syndrome critical region 1, known also as RCAN1, regulator of calcineurin 1) facilitates the drainage of waste products by increasing the coverage of dorsal meningeal lymphatic vessels. Furthermore, upregulation of DSCR1 in 5XFAD mice diminishes Aß pathology in the brain and improves memory defects. Surgical ligation of cervical lymphatic vessels afferent to dcLN blocks the beneficial effects of DSCR1 on Aß accumulation and cognitive function. Interestingly, intracerebroventricular delivery of AAV1-DSCR1 to 5XFAD mice is sufficient to rebuild the meningeal lymphatic system and re-establish cognitive performance. Collectively, our data indicate that DSCR1 facilitates the growth of dorsal meningeal lymphatics to improve drainage efficiency and protect against Alzheimer's disease (AD) pathologies, further highlighting that improving meningeal lymphatic function is a feasible treatment strategy for AD. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Doença de Alzheimer/patologia , Proteínas de Ligação ao Cálcio/metabolismo , Dura-Máter/metabolismo , Vasos Linfáticos , Proteínas Musculares/metabolismo , Placa Amiloide/patologia , Animais , Sistema Glinfático/metabolismo , Camundongos , Camundongos Transgênicos , Regulação para CimaRESUMO
BACKGROUND: The intrapartum period is a time of high mortality risk for newborns and mothers. Numerous interventions exist to minimize risk during this period. Data on intervention coverage are needed for health system improvement. Maternal report of intrapartum interventions through surveys is the primary source of coverage data, but they may be invalid or unreliable. METHODS: We assessed the reliability of maternal report of delivery and immediate newborn care for a sample of home and health facility births in Sarlahi, Nepal. Mothers were visited as soon as possible following delivery (< 72 h) and asked to report circumstances of labor and delivery. A subset was revisited 1-24 months after delivery and asked to recall interventions received using standard household survey questions. We assessed the reliability of each indicator by comparing what mothers reported immediately after delivery against what they reported at the follow-up survey. We assessed potential variation in reliability of maternal report by characteristics of the mother, birth event, or intervention prevalence. RESULTS: One thousand five hundred two mother/child pairs were included in the reliability study, with approximately half of births occurring at home. A higher proportion of women who delivered in facilities reported "don't know" when asked to recall specific interventions both initially and at follow-up. Most indicators had high observed percent agreement, but kappa values were below 0.4, indicating agreement was primarily due to chance. Only "received any injection during delivery" demonstrated high reliability among all births (kappa: 0.737). The reliability of maternal report was typically lower among women who delivered at a facility. There was no difference in reliability based on time since birth of the follow-up interview. We observed over-reporting of interventions at follow-up that were more common in the population and under-reporting of less common interventions. CONCLUSIONS: This study reinforces previous findings that mothers are unable to report reliably on many interventions within the peripartum period. Household surveys which rely on maternal report, therefore, may not be an appropriate method for collecting data on coverage of many interventions during the peripartum period. This is particularly true among facility births, where many interventions may occur without the mother's full knowledge.
Assuntos
Trabalho de Parto/psicologia , Rememoração Mental , Mães/psicologia , Período Periparto/psicologia , Autorrelato , Adulto , Feminino , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Visita Domiciliar , Humanos , Nepal , Gravidez , Apoio Social , Adulto JovemRESUMO
There is increasing evidence that children and adolescents can efficiently transmit SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (1-3). During July-August 2020, four state health departments and CDC investigated a COVID-19 outbreak that occurred during a 3-week family gathering of five households in which an adolescent aged 13 years was the index and suspected primary patient; 11 subsequent cases occurred.
Assuntos
Infecções por Coronavirus/epidemiologia , Surtos de Doenças , Família , Pneumonia Viral/epidemiologia , Adolescente , Adulto , Idoso , COVID-19 , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Estados Unidos/epidemiologia , Adulto JovemRESUMO
Limited data are available about transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), among youths. During June 17-20, an overnight camp in Georgia (camp A) held orientation for 138 trainees and 120 staff members; staff members remained for the first camp session, scheduled during June 21-27, and were joined by 363 campers and three senior staff members on June 21. Camp A adhered to the measures in Georgia's Executive Order* that allowed overnight camps to operate beginning on May 31, including requiring all trainees, staff members, and campers to provide documentation of a negative viral SARS-CoV-2 test ≤12 days before arriving. Camp A adopted most components of CDC's Suggestions for Youth and Summer Camps§ to minimize the risk for SARS-CoV-2 introduction and transmission. Measures not implemented were cloth masks for campers and opening windows and doors for increased ventilation in buildings. Cloth masks were required for staff members. Camp attendees were cohorted by cabin and engaged in a variety of indoor and outdoor activities, including daily vigorous singing and cheering. On June 23, a teenage staff member left camp A after developing chills the previous evening. The staff member was tested and reported a positive test result for SARS-CoV-2 the following day (June 24). Camp A officials began sending campers home on June 24 and closed the camp on June 27. On June 25, the Georgia Department of Public Health (DPH) was notified and initiated an investigation. DPH recommended that all attendees be tested and self-quarantine, and isolate if they had a positive test result.
Assuntos
Acampamento , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/transmissão , Surtos de Doenças , Pneumonia Viral/epidemiologia , Pneumonia Viral/transmissão , Adolescente , Adulto , COVID-19 , Criança , Feminino , Georgia/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Adulto JovemRESUMO
The Method Information Index (MII) is calculated from contraceptive users' responses to questions regarding counseling content-whether they were informed about methods other than the one they received, told about method-specific side effects, and advised what to do if they experienced side effects. The MII is increasingly reported in national surveys and used to track program performance, but little is known about its properties. Using additional questions, we assessed the consistency between responses and the method received in a prospective, multicountry study. We employed two definitions of consistency: (1) presence of any concordant response, and (2) absence of discordant responses. Consistency was high when asking whether users were informed about other methods and what to do about side effects. Responses were least consistent when asking whether side effects were mentioned. Adjusting for inconsistency, scores were up to 50 percent and 30 percent lower in Pakistan and Uganda, respectively, compared to unadjusted MII scores. Additional questions facilitated better understanding of counseling quality.
Assuntos
Anticoncepção , Aconselhamento/normas , Educação de Pacientes como Assunto/normas , Qualidade da Assistência à Saúde , Adolescente , Adulto , Estudos de Coortes , Feminino , Humanos , Pessoa de Meia-Idade , Paquistão , Estudos Prospectivos , Inquéritos e Questionários , Uganda , Adulto JovemRESUMO
Stem cells depend critically on the surrounding microenvironment, or niche, for their maintenance and self-renewal. While much is known about how the niche regulates stem cell self-renewal and differentiation, mechanisms for how the niche is maintained over time are not well understood. At the apical tip of the Drosophila testes, germline stem cells (GSCs) and somatic stem cells share a common niche formed by hub cells. Here we demonstrate that a novel protein named Shriveled (Shv) is necessary for the maintenance of hub/niche integrity. Depletion of Shv protein results in age-dependent deterioration of the hub structure and loss of GSCs, whereas upregulation of Shv preserves the niche during aging. We find Shv is a secreted protein that modulates DE-cadherin levels through extracellular activation of integrin signaling. Our work identifies Shv as a novel activator of integrin signaling and suggests a new integration model in which crosstalk between integrin and DE-cadherin in niche cells promote their own preservation by maintaining the niche architecture.
Assuntos
Caderinas/genética , Diferenciação Celular/genética , Proteínas de Drosophila/genética , Integrinas/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Nicho de Células-Tronco/genética , Animais , Caderinas/metabolismo , Adesão Celular/genética , Autorrenovação Celular/genética , Microambiente Celular/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Células Germinativas/crescimento & desenvolvimento , Integrinas/biossíntese , Masculino , Testículo/crescimento & desenvolvimento , Testículo/metabolismoRESUMO
Activity-induced synaptic structural modification is crucial for neural development and synaptic plasticity, but the molecular players involved in this process are not well defined. Here, we report that a protein named Shriveled (Shv) regulates synaptic growth and activity-dependent synaptic remodeling at the Drosophila neuromuscular junction. Depletion of Shv causes synaptic overgrowth and an accumulation of immature boutons. We find that Shv physically and genetically interacts with ßPS integrin. Furthermore, Shv is secreted during intense, but not mild, neuronal activity to acutely activate integrin signaling, induce synaptic bouton enlargement, and increase postsynaptic glutamate receptor abundance. Consequently, loss of Shv prevents activity-induced synapse maturation and abolishes post-tetanic potentiation, a form of synaptic plasticity. Our data identify Shv as a novel trans-synaptic signal secreted upon intense neuronal activity to promote synapse remodeling through integrin receptor signaling.SIGNIFICANCE STATEMENT The ability of neurons to rapidly modify synaptic structure in response to neuronal activity, a process called activity-induced structural remodeling, is crucial for neuronal development and complex brain functions. The molecular players that are important for this fundamental biological process are not well understood. Here we show that the Shriveled (Shv) protein is required during development to maintain normal synaptic growth. We further demonstrate that Shv is selectively released during intense neuronal activity, but not mild neuronal activity, to acutely activate integrin signaling and trigger structural modifications at the Drosophila neuromuscular junction. This work identifies Shv as a key modulator of activity-induced structural remodeling and suggests that neurons use distinct molecular cues to differentially modulate synaptic growth and remodeling to meet synaptic demand.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila/anatomia & histologia , Drosophila/fisiologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Junção Neuromuscular/citologia , Junção Neuromuscular/fisiologia , Plasticidade Neuronal/fisiologia , Potenciais de Ação/fisiologia , Animais , Células Cultivadas , Transdução de Sinais/fisiologiaRESUMO
UNLABELLED: The rapid replenishment of synaptic vesicles through endocytosis is crucial for sustaining synaptic transmission during intense neuronal activity. Synaptojanin (Synj), a phosphoinositide phosphatase, is known to play an important role in vesicle recycling by promoting the uncoating of clathrin following synaptic vesicle uptake. Synj has been shown to be a substrate of the minibrain (Mnb) kinase, a fly homolog of the dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A); however, the functional impacts of Synj phosphorylation by Mnb are not well understood. Here we identify that Mnb phosphorylates Synj at S1029 in Drosophila We find that phosphorylation of Synj at S1029 enhances Synj phosphatase activity, alters interaction between Synj and endophilin, and promotes efficient endocytosis of the active cycling vesicle pool (also referred to as exo-endo cycling pool) at the expense of reserve pool vesicle endocytosis. Dephosphorylated Synj, on the other hand, is deficient in the endocytosis of the active recycling pool vesicles but maintains reserve pool vesicle endocytosis to restore total vesicle pool size and sustain synaptic transmission. Together, our findings reveal a novel role for Synj in modulating reserve pool vesicle endocytosis and further indicate that dynamic phosphorylation and dephosphorylation of Synj differentially maintain endocytosis of distinct functional synaptic vesicle pools. SIGNIFICANCE STATEMENT: Synaptic vesicle endocytosis sustains communication between neurons during a wide range of neuronal activities by recycling used vesicle membrane and protein components. Here we identify that Synaptojanin, a protein with a known role in synaptic vesicle endocytosis, is phosphorylated at S1029 in vivo by the Minibrain kinase. We further demonstrate that the phosphorylation status of Synaptojanin at S1029 differentially regulates its participation in the recycling of distinct synaptic vesicle pools. Our results reveal a new role for Synaptojanin in maintaining synaptic vesicle pool size and in reserve vesicle endocytosis. As Synaptojanin and Minibrain perturbations are associated with various neurological disorders, such as Parkinson's, autism, and Down syndrome, understanding mechanisms modulating Synaptojanin function provides valuable insights into processes affecting neuronal communication.
Assuntos
Endocitose/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Junção Neuromuscular/fisiologia , Monoéster Fosfórico Hidrolases/metabolismo , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/fisiologia , Aciltransferases/genética , Aciltransferases/metabolismo , Fosfatase Alcalina/farmacologia , Animais , Animais Geneticamente Modificados , Ciclosporina/farmacologia , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Endocitose/efeitos dos fármacos , Endocitose/genética , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Imunoprecipitação , Técnicas In Vitro , Larva , Espectrometria de Massas , Mesencéfalo/citologia , Mesencéfalo/metabolismo , Microscopia Confocal , Mutagênese Sítio-Dirigida , Proteínas do Tecido Nervoso/genética , Junção Neuromuscular/efeitos dos fármacos , Técnicas de Patch-Clamp , Fosfatos de Fosfatidilinositol/metabolismo , Monoéster Fosfórico Hidrolases/genética , Fosforilação/genética , Serina/metabolismo , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/genética , Vesículas Sinápticas/genéticaRESUMO
Aging individuals with Down syndrome (DS) have an increased risk of developing Alzheimer's disease (AD), a neurodegenerative disorder characterized by impaired memory. Memory problems in both DS and AD individuals usually develop slowly and progressively get worse with age, but the cause of this age-dependent memory impairment is not well understood. This study examines the functional interactions between Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. Using Drosophila as a model, we find that overexpression of nebula (fly homolog of DSCR1) initially protects against APP-induced memory defects by correcting calcineurin and cAMP signaling pathways but accelerates the rate of memory loss and exacerbates mitochondrial dysfunction in older animals. We report that transient upregulation of Nebula/DSCR1 or acute pharmacological inhibition of calcineurin in aged flies protected against APP-induced memory loss. Our data suggest that calcineurin dyshomeostasis underlies age-dependent memory impairments and further imply that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory impairments in AD in DS. SIGNIFICANCE STATEMENT: Most Down syndrome (DS) individuals eventually develop Alzheimer's disease (AD)-like dementia, but mechanisms underlying this age-dependent memory impairment remain poorly understood. This study examines Nebula/Down syndrome critical region 1 (DSCR1) and amyloid-precursor protein (APP), proteins upregulated in both DS and AD, in regulating memory. We uncover a previously unidentified role for Nebula/DSCR1 in modulating APP-induced memory defects during aging. We show that upregulation of Nebula/DSCR1, an inhibitor of calcineurin, rescues APP-induced memory defects in young flies but enhances memory loss of older flies. Excitingly, transient Nebula/DSCR1 overexpression or calcineurin inhibition in aged flies ameliorates APP-mediated memory problems. These results suggest that chronic Nebula/DSCR1 upregulation may contribute to age-dependent memory loss in DS and AD and points to correcting calcineurin signaling as a means to improve memory during aging.
Assuntos
Doença de Alzheimer/metabolismo , Síndrome de Down/metabolismo , Proteínas de Drosophila/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Transtornos da Memória/metabolismo , Precursor de Proteína beta-Amiloide , Animais , Calcineurina/metabolismo , Proteínas de Ligação ao Cálcio , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster , Peptídeos e Proteínas de Sinalização Intracelular/genética , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/genética , Regulação para CimaRESUMO
Most common genetic factors known to cause intellectual disability are Down syndrome and Fragile X syndrome. However, the underlying cellular and molecular mechanisms of intellectual disability remain unclear. Recently, dendritic spine dysmorphogenesis and impaired local protein synthesis are posited to contribute to the cellular mechanisms of intellectual disability. Here, we show that Down syndrome critical region1 (DSCR1) interacts with Fragile X mental retardation protein (FMRP) and regulates both dendritic spine morphogenesis and local protein synthesis. Interestingly, decreasing the level of FMRP restores the DSCR1-induced changes in dendritic spine morphology. Our results imply that DSCR1 is a novel regulator of FMRP and that Fragile X syndrome and Down syndrome may share disturbances in common pathways that regulate dendritic spine morphology and local protein synthesis.
Assuntos
Espinhas Dendríticas/metabolismo , Proteína do X Frágil da Deficiência Intelectual/fisiologia , Regulação da Expressão Gênica , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Proteínas Musculares/fisiologia , Animais , Região CA1 Hipocampal , Proteínas de Ligação ao Cálcio , Proteínas de Ligação a DNA , Síndrome de Down/genética , Síndrome de Down/metabolismo , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/metabolismo , Células HEK293 , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional/métodos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Morfogênese , Proteínas Musculares/metabolismo , Neurônios/metabolismo , Fosforilação , RNA Interferente Pequeno/metabolismoRESUMO
Post-mortem brains from Down syndrome (DS) and Alzheimer's disease (AD) patients show an upregulation of the Down syndrome critical region 1 protein (DSCR1), but its contribution to AD is not known. To gain insights into the role of DSCR1 in AD, we explored the functional interaction between DSCR1 and the amyloid precursor protein (APP), which is known to cause AD when duplicated or upregulated in DS. We find that the Drosophila homolog of DSCR1, Nebula, delays neurodegeneration and ameliorates axonal transport defects caused by APP overexpression. Live-imaging reveals that Nebula facilitates the transport of synaptic proteins and mitochondria affected by APP upregulation. Furthermore, we show that Nebula upregulation protects against axonal transport defects by restoring calcineurin and GSK-3ß signaling altered by APP overexpression, thereby preserving cargo-motor interactions. As impaired transport of essential organelles caused by APP perturbation is thought to be an underlying cause of synaptic failure and neurodegeneration in AD, our findings imply that correcting calcineurin and GSK-3ß signaling can prevent APP-induced pathologies. Our data further suggest that upregulation of Nebula/DSCR1 is neuroprotective in the presence of APP upregulation and provides evidence for calcineurin inhibition as a novel target for therapeutic intervention in preventing axonal transport impairments associated with AD.
Assuntos
Doença de Alzheimer/genética , Precursor de Proteína beta-Amiloide/genética , Calcineurina/genética , Síndrome de Down/genética , Proteínas de Drosophila/genética , Quinase 3 da Glicogênio Sintase/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Doença de Alzheimer/patologia , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Transporte Axonal/genética , Axônios/metabolismo , Axônios/patologia , Calcineurina/metabolismo , Proteínas de Ligação ao Cálcio , Proteínas de Ligação a DNA , Síndrome de Down/patologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Proteínas Musculares/genética , Transdução de Sinais , Regulação para CimaRESUMO
The proper distribution of mitochondria is particularly vital for neurons because of their polarized structure and high energy demand. Mitochondria in axons constantly move in response to physiological needs, but signals that regulate mitochondrial movement are not well understood. Aside from producing ATP, Ca(2+) buffering is another main function of mitochondria. Activities of many enzymes in mitochondria are also Ca(2+)-dependent, suggesting that intramitochondrial Ca(2+) concentration is important for mitochondrial functions. Here, we report that mitochondrial motility in axons is actively regulated by mitochondrial matrix Ca(2+). Ca(2+) entry through the mitochondrial Ca(2+) uniporter modulates mitochondrial transport, and mitochondrial Ca(2+) content correlates inversely with the speed of mitochondrial movement. Furthermore, the miro1 protein plays a role in Ca(2+) uptake into the mitochondria, which subsequently affects mitochondrial movement.
Assuntos
Axônios/metabolismo , Sinalização do Cálcio , Cálcio/metabolismo , Mitocôndrias/metabolismo , Animais , Canais de Cálcio/metabolismo , Motivos EF Hand , Humanos , Camundongos , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Movimento , Mutação/genéticaRESUMO
When exposed to new experiences or changes in the environment, neurons rapidly remodel their synaptic structure and function in a process called activity-induced synaptic remodeling. This process is necessary for transforming transient experiences into stable, lasting memories. The molecular mechanisms underlying acute, activity-dependent synaptic changes are not well understood, partly because processes regulating synaptic plasticity and neurodevelopment are intricately linked. By using an RNAi screen in Drosophila targeting genes associated with human nervous system function, we found that while macroautophagy (referred to as autophagy) is fundamental for both synapse development and synaptic plasticity, activity-induced synaptic remodeling does not rely on genes associated with lysosomal degradation. These findings suggest a requirement for the unconventional secretory autophagy pathway in regulating synaptic plasticity, wherein autophagosomes, instead of fusing with lysosomes for degradation, fuse with the plasma membrane to release their contents extracellularly. To test this hypothesis, we knocked down Sec22, Snap29, and Rab8, molecular components required for secretory autophagy, all of which disrupted structural and functional plasticity. Additionally, by monitoring autophagy, we demonstrated that neuronal activity suppresses degradative autophagy to shift the pathway toward secretory autophagy release. Our work unveils secretory autophagy as a novel trans-synaptic signaling mechanism crucial for activity-induced synaptic remodeling.
RESUMO
The ability of neurons to rapidly remodel their synaptic structure and strength in response to neuronal activity is highly conserved across species and crucial for complex brain functions. However, mechanisms required to elicit and coordinate the acute, activity-dependent structural changes across synapses are not well understood. Here, using an RNAi screen in Drosophila against genes affecting nervous system functions in humans, we uncouple cellular processes important for synaptic plasticity from synapse development. We find mutations associated with neurodegenerative and mental health disorders are 2-times more likely to affect activity-induced synaptic remodeling than synapse development. We further demonstrate that neuronal activity stimulates autophagy activation but diminishes degradative autophagy, thereby driving the pathway towards autophagy-based secretion. Presynaptic knockdown of Snap29, Sec22, or Rab8, proteins implicated in the secretory autophagy pathway, is sufficient to abolish activity-induced synaptic remodeling. This study uncovers secretory autophagy as a novel trans-synaptic signaling mechanism modulating structural plasticity.
RESUMO
At the neuronal level of Down syndrome (DS) brains, there are evidences of altered shape, number, and density of synapses, as well as aberrant endocytosis associated with accumulation of enlarged endosomes, suggesting that proteins involved in synaptic vesicle recycling may play key roles in DS neurons. However, the exact mechanism underlying those anomalies is not well understood. We hypothesize that overexpression of three genes, dap160/itsn1, synj/synj1, and nla/dscr1, located on human chromosome 21 play important roles in DS neurons. Here, we systematically investigate the effects of multiple gene overexpression on synaptic morphology and endocytosis to identify possible dominant gene or genes. We found that overexpression of individual genes lead to abnormal synaptic morphology, but all three genes are necessary to cause impaired vesicle recycling and affect locomotor vigor. Furthermore, we report that dap160 overexpression alters the subcellular distribution of synaptojanin, and overexpression of nla regulates the phosphoinositol 5' phosphatase activity of synaptojanin. These findings imply that restoring the level of any one of these genes may reduce endocytic defects seen in DS.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Terminações Pré-Sinápticas/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Animais Geneticamente Modificados , Western Blotting , Proteínas de Ligação ao Cálcio , Cromossomos Humanos Par 21/genética , Proteínas de Ligação a DNA , Síndrome de Down/genética , Síndrome de Down/metabolismo , Síndrome de Down/fisiopatologia , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Endocitose , Potenciais Evocados , Potenciais Pós-Sinápticos Excitadores , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Larva/genética , Larva/metabolismo , Larva/fisiologia , Modelos Biológicos , Atividade Motora/fisiologia , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Neurônios/fisiologia , Monoéster Fosfórico Hidrolases/genética , Terminações Pré-Sinápticas/fisiologia , Regulação para Cima , Proteínas de Transporte Vesicular/genéticaRESUMO
OBJECTIVES: Zika virus (ZIKV) can be sexually transmitted, and ZIKV infection during pregnancy can cause birth defects. Contraception is a medical countermeasure to reduce unintended pregnancy and ZIKV-associated birth defects. We estimated the prevalence of condom use and associated factors among women at risk for unintended pregnancy in Puerto Rico during the 2016 ZIKV outbreak. DESIGN: Secondary analysis of a cross-sectional, population-based, cell-phone survey. SETTING AND PARTICIPANTS: Women, 18-49 years, living in Puerto Rico during July-November 2016. We limited our analytical sample (n=1840) to women at risk for unintended pregnancy, defined as those who were sexually active with a man in the last 3 months and did not report menopause, hysterectomy, current pregnancy or desiring pregnancy. OUTCOME MEASURES: We estimated the weighted prevalence of any condom use among women at risk for unintended pregnancy. We calculated crude and adjusted prevalence ratios (aPRs) to examine the association between condom use and ZIKV-related factors, stratified by use of more effective versus less effective or no contraception. RESULTS: Overall, 32.7% (95% CI: 30.2% to 35.1%) of women reported any condom use in the last 3 months. Among women using more effective contraception, condom use was higher for women who received ZIKV counselling (aPR: 1.61, 95% CI: 1.15 to 2.25) and those worried about having a child with a ZIKV-associated birth defect (aPR: 1.47, 95% CI: 1.03 to 2.10). Among women using less effective or no contraception, condom use was associated with being worried (aPR: 1.20, 95% CI: 1.01 to 1.43) compared with those not worried about ZIKV infection or with a previous known infection. CONCLUSIONS: During the 2016 ZIKV outbreak, one in three women at risk for unintended pregnancy reported any condom use. Counselling to promote consistent and correct condom use may address concerns regarding ZIKV among women of reproductive age, which may differ by use of effective contraception.