RESUMO
Social memory processing requires functional CA2 neurons, however the specific mechanisms that regulate their activity are poorly understood. Here, we document that SorCS2, a member of the family of the Vps10 family of sorting receptors, is highly expressed in pyramidal neurons of CA2, as well as ventral CA1, a circuit implicated in social memory. SorCS2 specifically localizes to the postsynaptic density and endosomes within dendritic spines of CA2 neurons. We have discovered that SorCS2 is a selective regulator of NMDA receptor surface trafficking in hippocampal neurons, without altering AMPA receptor trafficking. In addition, SorCS2 regulates dendritic spine density in CA2 neurons where SorCS2 expression is enriched, but not in dorsal CA1 neurons, which normally express very low levels of this protein. To specifically test the role of SorCS2 in behavior, we generated a novel SorCS2-deficient mouse, and identify a significant social memory deficit, with no change in sociability, olfaction, anxiety, or several hippocampal-dependent behaviors. Mutations in sorCS2 have been associated with bipolar disease, schizophrenia, and attention deficient-hyperactivity disorder, and abnormalities in social memory are core components of these neuropsychiatric conditions. Thus, our findings provide a new mechanism for social memory formation, through regulating synaptic receptor trafficking in pyramidal neurons by SorCS2.
Assuntos
Memória , Proteínas do Tecido Nervoso , Células Piramidais , Receptores de Superfície Celular , Receptores de N-Metil-D-Aspartato , Animais , Espinhas Dendríticas/metabolismo , Hipocampo/metabolismo , Camundongos , Neurônios/metabolismo , Células Piramidais/metabolismo , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
Biological microscopic analysis is a popular method employed in wastewater treatment plants worldwide for evaluating activated sludge condition. However, many operators still have reservations regarding its reliability. In this study, we evaluated and compared two methods of microscopic sludge investigation: the sludge index (SI) and the Eikelboom-van Buijsen method (EB). We investigated 79 activated sludge samples from nine treatment plants located in southern Poland over a 1-year period. For each sample, sludge volume index values were calculated and compared with the results of evaluation made on the basis of microscopic analysis. Additionally, the effluent quality was analysed in 45 of 79 cases, including investigation of suspended solids, biochemical oxygen demand, chemical oxygen demand, total nitrogen and total phosphorous. The sign test and Wilcoxon matched pairs test showed that a significant difference existed between the two investigated methods. General conclusions from both methods do not provide reliable information concerning nitrogen and phosphorus removal. The EB method had a tendency to be more conservative in its general conclusions than the SI method. Both are highly reliable for estimating activated sludge quality and solid separation properties.
Assuntos
Eliminação de Resíduos Líquidos/métodos , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Nitrogênio/análise , Fósforo/análise , Polônia , Reprodutibilidade dos Testes , Esgotos/químicaRESUMO
Neurons integrate and encode complex synaptic inputs into action potential outputs through a process termed "intrinsic excitability." Here, we report the essential contribution of fibroblast growth factor homologous factors (FHFs), a family of voltage-gated sodium channel binding proteins, to this process. Fhf1-/-Fhf4-/- mice suffer from severe ataxia and other neurological deficits. In mouse cerebellar slice recordings, WT granule neurons can be induced to fire action potentials repetitively (approximately 60 Hz), whereas Fhf1-/-Fhf4-/- neurons often fire only once and at an elevated voltage spike threshold. Sodium channels in Fhf1-/-Fhf4-/- granule neurons inactivate at more negative membrane potential, inactivate more rapidly, and are slower to recover from the inactivated state. Altered sodium channel physiology is sufficient to explain excitation deficits, as tested in a granule cell computer model. These findings offer a physiological mechanism underlying human spinocerebellar ataxia induced by Fhf4 mutation and suggest a broad role for FHFs in the control of excitability throughout the CNS.
Assuntos
Fator 4 de Crescimento de Fibroblastos/fisiologia , Fatores de Crescimento de Fibroblastos/fisiologia , Ativação do Canal Iônico , Neurônios/fisiologia , Canais de Sódio/fisiologia , Potenciais de Ação , Animais , Células Cultivadas , Cerebelo/anatomia & histologia , Cerebelo/citologia , Estimulação Elétrica , Eletrofisiologia , Fator 4 de Crescimento de Fibroblastos/deficiência , Fatores de Crescimento de Fibroblastos/deficiência , Técnicas In Vitro , Potenciais da Membrana , Camundongos , Camundongos Knockout , Modelos Neurológicos , Atividade Motora/fisiologia , Neurônios/citologia , Neurônios/metabolismo , Técnicas de Patch-ClampRESUMO
Deletion of the human SHANK3 gene near the terminus of chromosome 22q is associated with Phelan-McDermid syndrome and autism spectrum disorders. Nearly all such deletions also span the tightly linked IB2 gene. We show here that IB2 protein is broadly expressed in the brain and is highly enriched within postsynaptic densities. Experimental disruption of the IB2 gene in mice reduces AMPA and enhances NMDA receptor-mediated glutamatergic transmission in cerebellum, changes the morphology of Purkinje cell dendritic arbors, and induces motor and cognitive deficits suggesting an autism phenotype. These findings support a role for human IB2 mutation as a contributing genetic factor in Chr22qter-associated cognitive disorders.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Doenças Cerebelares/genética , Transtornos Globais do Desenvolvimento Infantil/genética , Transtornos Globais do Desenvolvimento Infantil/fisiopatologia , Transmissão Sináptica/genética , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Animais , Doenças Cerebelares/metabolismo , Doenças Cerebelares/fisiopatologia , Transtornos Globais do Desenvolvimento Infantil/metabolismo , Cromossomos Humanos Par 22/genética , Transtornos Cognitivos/genética , Transtornos Cognitivos/metabolismo , Transtornos Cognitivos/fisiopatologia , Modelos Animais de Doenças , Feminino , Predisposição Genética para Doença/genética , Humanos , Recém-Nascido , Masculino , Transtornos Mentais/genética , Transtornos Mentais/metabolismo , Transtornos Mentais/fisiopatologia , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Receptores de AMPA/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
Select adhesion molecules connect pre- and postsynaptic membranes and organize developing synapses. The regulation of these trans-synaptic interactions is an important neurobiological question. We have previously shown that the synaptic cell adhesion molecules (SynCAMs) 1 and 2 engage in homo- and heterophilic interactions and bridge the synaptic cleft to induce presynaptic terminals. Here, we demonstrate that site-specific N-glycosylation impacts the structure and function of adhesive SynCAM interactions. Through crystallographic analysis of SynCAM 2, we identified within the adhesive interface of its Ig1 domain an N-glycan on residue Asn(60). Structural modeling of the corresponding SynCAM 1 Ig1 domain indicates that its glycosylation sites Asn(70)/Asn(104) flank the binding interface of this domain. Mass spectrometric and mutational studies confirm and characterize the modification of these three sites. These site-specific N-glycans affect SynCAM adhesion yet act in a differential manner. Although glycosylation of SynCAM 2 at Asn(60) reduces adhesion, N-glycans at Asn(70)/Asn(104) of SynCAM 1 increase its interactions. The modification of SynCAM 1 with sialic acids contributes to the glycan-dependent strengthening of its binding. Functionally, N-glycosylation promotes the trans-synaptic interactions of SynCAM 1 and is required for synapse induction. These results demonstrate that N-glycosylation of SynCAM proteins differentially affects their binding interface and implicate post-translational modification as a mechanism to regulate trans-synaptic adhesion.
Assuntos
Moléculas de Adesão Celular Neuronais/química , Ácido N-Acetilneuramínico/química , Terminações Pré-Sinápticas/química , Animais , Células COS , Adesão Celular/fisiologia , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Chlorocebus aethiops , Cristalografia por Raios X , Glicosilação , Humanos , Espectrometria de Massas , Mutação , Ácido N-Acetilneuramínico/genética , Ácido N-Acetilneuramínico/metabolismo , Terminações Pré-Sinápticas/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Estrutura Terciária de ProteínaRESUMO
Human brain derived neurotrophic factor (BDNF) encodes a protein product consisting of a C-terminal mature domain (mature BDNF) and an N-terminal prodomain, which is an intrinsically disordered protein. A common single nucleotide polymorphism in humans results in a methionine substitution for valine at position 66 of the prodomain, and is associated with memory deficits, depression and anxiety disorders. The BDNF Met66 prodomain, but not the Val66 prodomain, promotes rapid structural remodeling of hippocampal neurons' growth cones and dendritic spines by interacting directly with the SorCS2 receptor. While it has been reported that the Met66 and Val66 prodomains exhibit only modest differences in structural propensities in the apo state, here we show that Val66 and Met66 prodomains differentially bind zinc (Zn). Zn2+ binds with higher affinity and more broadly impacts residues on the Met66 prodomain compared to the Val66 prodomain as shown by NMR and ITC. Zn2+ binding to the Met66 and Val66 prodomains results in distinct conformational and macroscopic differences observed by NMR, light scattering and cryoEM. To determine if Zn2+ mediated conformational change in the Met66 prodomain is required for biological effect, we mutated His40, a Zn2+ binding site, and observed a loss of Met66 prodomain bioactivity. As the His40 site is distant from the known region of the prodomain involved in receptor binding, we suggest that Met66 prodomain bioactivity involves His40 mediated stabilization of the multimeric structure. Our results point to the necessity of a Zn2+-mediated higher order molecular assembly of the Met66 prodomain to mediate neuronal remodeling.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/química , Zinco/química , Sítios de Ligação , Espectroscopia de Ressonância Magnética , Proteínas do Tecido Nervoso/química , Ligação ProteicaRESUMO
A human variant in the BDNF gene (Val66Met; rs6265) is associated with impaired fear extinction. Using super-resolution imaging, we demonstrate that the BDNF Met prodomain disassembles dendritic spines and eliminates synapses in hippocampal neurons. In vivo, ventral CA1 (vCA1) hippocampal neurons undergo similar morphological changes dependent on their transient co-expression of a SorCS2/p75NTR receptor complex during peri-adolescence. BDNF Met prodomain infusion into the vCA1 during this developmental time frame reduces dendritic spine density and prelimbic (PL) projections, impairing cued fear extinction. Adolescent BdnfMet/Met mice display similar spine and PL innervation deficits. Using fiber photometry, we found that, in wild-type mice, vCA1 neurons projecting to the PL encode extinction by enhancing neural activity in threat anticipation and rapidly subsiding their response. This adaptation is absent in BDNFMet/Met mice. We conclude that the BDNF Met prodomain renders vCA1-PL projection neurons underdeveloped, preventing their capacity for subsequent circuit modulation necessary for fear extinction. VIDEO ABSTRACT.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/genética , Região CA1 Hipocampal/patologia , Espinhas Dendríticas/patologia , Extinção Psicológica , Medo , Neurônios/patologia , Sinapses/patologia , Animais , Região CA1 Hipocampal/fisiopatologia , Camundongos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Anandamide (AEA)-dependent signaling is regulated by the catabolic enzyme fatty acid amide hydrolase (FAAH). Several lines of evidence have demonstrated that FAAH and AEA are involved in the behavioral effects of alcohol. Therefore, we investigated whether a selective FAAH inhibitor, URB597 (cyclohexylcarbamic acid 3'-[aminocarbonyl]-[1,1'-biphenyl]-3-yl ester), altered alcohol intake in mice in a voluntary alcohol drinking model. METHODS: Mice, subjected to 3 weeks of chronic intermittent access (IA) in a two-bottle choice paradigm with 24-h access every other day, developed rapid escalation of alcohol intake and high preference. We evaluated the pharmacological effects of URB597 after both acute (1-day) withdrawal from chronic IA and 1-week withdrawal using the alcohol deprivation effect (ADE) model. AEA and N-acyl ethanolamide (NAE) abundances were determined after chronic IA, acute (1-day), or long-term (1 and 2 weeks) withdrawal in four brain regions. RESULTS: Acute pretreatment with URB597 reduced alcohol intake and preference after acute withdrawal. This effect was blocked by pretreatment with a selective type 1 cannabinoid receptor (CB1) antagonist, suggesting a CB1-mediated mechanism. Both single- and multiple-dosing regimens with an effective dose of URB597 prevented the ADE, with no tolerance development after the multi-dosing regimen. AEA and NAE levels were transiently increased in all brain regions measured after acute withdrawal, indicating that the endocannabinoid system is involved in acute alcohol withdrawal stress response. CONCLUSION: FAAH inhibitors reduce alcohol escalation and "relapse" drinking in mice.
Assuntos
Consumo de Bebidas Alcoólicas/tratamento farmacológico , Amidoidrolases/antagonistas & inibidores , Amidoidrolases/metabolismo , Benzamidas/farmacologia , Carbamatos/farmacologia , Consumo de Bebidas Alcoólicas/metabolismo , Alcoolismo/tratamento farmacológico , Alcoolismo/enzimologia , Animais , Benzamidas/uso terapêutico , Carbamatos/uso terapêutico , Endocanabinoides/metabolismo , Etanol/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Distribuição Aleatória , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB1 de Canabinoide/metabolismo , RecidivaRESUMO
Recent studies in humans and in genetic mouse models have identified Slit- and NTRK-like family (Slitrks) as candidate genes for neuropsychiatric disorders. All Slitrk isotypes are highly expressed in the CNS, where they mediate neurite outgrowth, synaptogenesis, and neuronal survival. However, the molecular mechanisms underlying these functions are not known. Here, we report that Slitrk5 modulates brain-derived neurotrophic factor (BDNF)-dependent biological responses through direct interaction with TrkB receptors. Under basal conditions, Slitrk5 interacts primarily with a transsynaptic binding partner, protein tyrosine phosphatase δ (PTPδ); however, upon BDNF stimulation, Slitrk5 shifts to cis-interactions with TrkB. In the absence of Slitrk5, TrkB has a reduced rate of ligand-dependent recycling and altered responsiveness to BDNF treatment. Structured illumination microscopy revealed that Slitrk5 mediates optimal targeting of TrkB receptors to Rab11-positive recycling endosomes through recruitment of a Rab11 effector protein, Rab11-FIP3. Thus, Slitrk5 acts as a TrkB co-receptor that mediates its BDNF-dependent trafficking and signaling.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptor trkB/metabolismo , Animais , Corpo Estriado/metabolismo , Endossomos/metabolismo , Células HEK293 , Humanos , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Ligação Proteica , Transporte Proteico , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/metabolismo , Transdução de Sinais , Proteínas rab de Ligação ao GTP/metabolismoRESUMO
Drugs of abuse have acute and persistent effects on synapse structure and addiction-related behaviors. Trans-synaptic interactions can control synapse development, and synaptic cell adhesion molecule (SynCAM) proteins (also named nectin-like molecules) are immunoglobulin adhesion proteins that span the synaptic cleft and induce excitatory synapses. Our studies now reveal that the loss of SynCAM 1 in knockout (KO) mice reduces excitatory synapse number in nucleus accumbens (NAc). SynCAM 1 additionally contributes to the structural remodeling of NAc synapses in response to the psychostimulant cocaine. Specifically, we find that cocaine administration increases the density of stubby spines on medium spiny neurons in NAc, and that maintaining this increase requires SynCAM 1. Furthermore, mushroom-type spines on these neurons are structurally more plastic when SynCAM 1 is absent, and challenging drug-withdrawn mice with cocaine shortens these spines in SynCAM 1 KO mice. These effects are correlated with changes on the behavioral level, where SynCAM 1 contributes to the psychostimulant effects of cocaine as measured after acute and repeated administration, and in drug-withdrawn mice. Together, our results provide evidence that the loss of a synapse-organizing adhesion molecule can modulate cocaine effects on spine structures in NAc and increases vulnerability to the behavioral actions of cocaine. SynCAM-dependent pathways may therefore represent novel points of therapeutic intervention after exposure to drugs of abuse.