RESUMO
Neuronal mitochondria play important roles beyond ATP generation, including Ca2+ uptake, and therefore have instructive roles in synaptic function and neuronal response properties. Mitochondrial morphology differs significantly between the axon and dendrites of a given neuronal subtype, but in CA1 pyramidal neurons (PNs) of the hippocampus, mitochondria within the dendritic arbor also display a remarkable degree of subcellular, layer-specific compartmentalization. In the dendrites of these neurons, mitochondria morphology ranges from highly fused and elongated in the apical tuft, to more fragmented in the apical oblique and basal dendritic compartments, and thus occupy a smaller fraction of dendritic volume than in the apical tuft. However, the molecular mechanisms underlying this striking degree of subcellular compartmentalization of mitochondria morphology are unknown, precluding the assessment of its impact on neuronal function. Here, we demonstrate that this compartment-specific morphology of dendritic mitochondria requires activity-dependent, Ca2+ and Camkk2-dependent activation of AMPK and its ability to phosphorylate two direct effectors: the pro-fission Drp1 receptor Mff and the recently identified anti-fusion, Opa1-inhibiting protein, Mtfr1l. Our study uncovers a signaling pathway underlying the subcellular compartmentalization of mitochondrial morphology in dendrites of neurons in vivo through spatially precise and activity-dependent regulation of mitochondria fission/fusion balance.
Assuntos
Neurônios , Células Piramidais , Neurônios/metabolismo , Células Piramidais/fisiologia , Hipocampo , Axônios/metabolismo , Mitocôndrias/metabolismo , Dendritos/fisiologiaRESUMO
In neurons of the mammalian central nervous system (CNS), axonal mitochondria are thought to be indispensable for supplying ATP during energy-consuming processes such as neurotransmitter release. Here, we demonstrate using multiple, independent, in vitro and in vivo approaches that the majority (~80-90%) of axonal mitochondria in cortical pyramidal neurons (CPNs), lack mitochondrial DNA (mtDNA). Using dynamic, optical imaging analysis of genetically encoded sensors for mitochondrial matrix ATP and pH, we demonstrate that in axons of CPNs, but not in their dendrites, mitochondrial complex V (ATP synthase) functions in a reverse way, consuming ATP and protruding H+ out of the matrix to maintain mitochondrial membrane potential. Our results demonstrate that in mammalian CPNs, axonal mitochondria do not play a major role in ATP supply, despite playing other functions critical to regulating neurotransmission such as Ca2+ buffering.
RESUMO
Neuronal mitochondria play important roles beyond ATP generation, including Ca2+ uptake, and therefore have instructive roles in synaptic function and neuronal response properties. Mitochondrial morphology differs significantly in the axon and dendrites of a given neuronal subtype, but in CA1 pyramidal neurons (PNs) of the hippocampus, mitochondria within the dendritic arbor also display a remarkable degree of subcellular, layer-specific compartmentalization. In the dendrites of these neurons, mitochondria morphology ranges from highly fused and elongated in the apical tuft, to more fragmented in the apical oblique and basal dendritic compartments, and thus occupy a smaller fraction of dendritic volume than in the apical tuft. However, the molecular mechanisms underlying this striking degree of subcellular compartmentalization of mitochondria morphology are unknown, precluding the assessment of its impact on neuronal function. Here, we demonstrate that this compartment-specific morphology of dendritic mitochondria requires activity-dependent, Camkk2-dependent activation of AMPK and its ability to phosphorylate two direct effectors: the pro-fission Drp1 receptor Mff and the recently identified anti-fusion, Opa1-inhibiting protein, Mtfr1l. Our study uncovers a new activity-dependent molecular mechanism underlying the extreme subcellular compartmentalization of mitochondrial morphology in dendrites of neurons in vivo through spatially precise regulation of mitochondria fission/fusion balance.
RESUMO
Mitochondria are dynamic organelles that undergo membrane remodeling events in response to metabolic alterations to generate an adequate mitochondrial network. Here, we investigated the function of mitochondrial fission regulator 1-like protein (MTFR1L), an uncharacterized protein that has been identified in phosphoproteomic screens as a potential AMP-activated protein kinase (AMPK) substrate. We showed that MTFR1L is an outer mitochondrial membrane-localized protein modulating mitochondrial morphology. Loss of MTFR1L led to mitochondrial elongation associated with increased mitochondrial fusion events and levels of the mitochondrial fusion protein, optic atrophy 1. Mechanistically, we show that MTFR1L is phosphorylated by AMPK, which thereby controls the function of MTFR1L in regulating mitochondrial morphology both in mammalian cell lines and in murine cortical neurons in vivo. Furthermore, we demonstrate that MTFR1L is required for stress-induced AMPK-dependent mitochondrial fragmentation. Together, these findings identify MTFR1L as a critical mitochondrial protein transducing AMPK-dependent metabolic changes through regulation of mitochondrial dynamics.
Assuntos
Proteínas Quinases Ativadas por AMP , Dinâmica Mitocondrial , Animais , Camundongos , Fosforilação , Proteínas Quinases Ativadas por AMP/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Proteínas de Membrana/metabolismo , Mamíferos/metabolismoRESUMO
During the early stages of Alzheimer's disease (AD) in both mouse models and human patients, soluble forms of Amyloid-ß 1-42 oligomers (Aß42o) trigger loss of excitatory synapses (synaptotoxicity) in cortical and hippocampal pyramidal neurons (PNs) prior to the formation of insoluble amyloid plaques. In a transgenic AD mouse model, we observed a spatially restricted structural remodeling of mitochondria in the apical tufts of CA1 PNs dendrites corresponding to the dendritic domain where the earliest synaptic loss is detected in vivo. We also observed AMPK over-activation as well as increased fragmentation and loss of mitochondrial biomass in Ngn2-induced neurons derived from a new APPSwe/Swe knockin human ES cell line. We demonstrate that Aß42o-dependent over-activation of the CAMKK2-AMPK kinase dyad mediates synaptic loss through coordinated phosphorylation of MFF-dependent mitochondrial fission and ULK2-dependent mitophagy. Our results uncover a unifying stress-response pathway causally linking Aß42o-dependent structural remodeling of dendritic mitochondria to synaptic loss.
Assuntos
Doença de Alzheimer , Mitofagia , Proteínas Quinases Ativadas por AMP/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/genética , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/metabolismo , Modelos Animais de Doenças , Camundongos , Camundongos Transgênicos , Dinâmica Mitocondrial , Fragmentos de Peptídeos , Sinapses/metabolismoRESUMO
The molecular and cellular mechanisms underlying complex axon morphogenesis are still poorly understood. We report a novel, evolutionary conserved function for the Drosophila Wnk kinase (dWnk) and its mammalian orthologs, WNK1 and 2, in axon branching. We uncover that dWnk, together with the neuroprotective factor Nmnat, antagonizes the axon-destabilizing factors D-Sarm and Axundead (Axed) during axon branch growth, revealing a developmental function for these proteins. Overexpression of D-Sarm or Axed results in axon branching defects, which can be blocked by overexpression of dWnk or Nmnat. Surprisingly, Wnk kinases are also required for axon maintenance of adult Drosophila and mouse cortical pyramidal neurons. Requirement of Wnk for axon maintenance is independent of its developmental function. Inactivation of dWnk or mouse Wnk1/2 in mature neurons leads to axon degeneration in the adult brain. Therefore, Wnk kinases are novel signaling components that provide a safeguard function in both developing and adult axons.
Assuntos
Proteínas do Domínio Armadillo/biossíntese , Axônios/metabolismo , Proteínas do Citoesqueleto/biossíntese , Proteínas de Drosophila/biossíntese , Evolução Molecular , Morfogênese/fisiologia , Proteínas Serina-Treonina Quinases/biossíntese , Animais , Proteínas do Domínio Armadillo/antagonistas & inibidores , Proteínas do Domínio Armadillo/genética , Linhagem Celular Tumoral , Proteínas do Citoesqueleto/antagonistas & inibidores , Proteínas do Citoesqueleto/genética , Proteínas de Drosophila/antagonistas & inibidores , Proteínas de Drosophila/genética , Drosophila melanogaster , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Gravidez , Proteínas Serina-Treonina Quinases/genéticaRESUMO
Gut motility malfunction and pathological changes in the enteric nervous system (ENS) are observed in the early stages of Parkinson's disease (PD). In many cases disturbances in the autonomous functions such as gut motility precedes the observed loss of central motor functions in PD. However, the mechanism by which ENS degeneration occurs in PD is unknown. We show that parkinsonian mimetics rotenone and MPP+ induce neurite degeneration that precedes cell death in primary enteric neurons cultured in vitro. If the neuronal death signals originate from degenerating neurites, neuronal death should be prevented by inhibiting neurite degeneration. Our data demonstrate that overexpression of cytNmnat1, an axon protector, maintains healthy neurites in enteric neurons treated with either of the parkinsonian mimetics, but cannot protect the soma. We also demonstrate that neurite protection via cytNmnat1 is independent of mitochondrial dynamics or ATP levels. Overexpression of Bcl-xl, an anti-apoptotic factor, protects both the neuronal cell body and the neurites in both rotenone and MPP+ treated enteric neurons. Our data reveals that Bcl-xl and cytNmnat1 act through separate mechanisms to protect enteric neurites. Our findings suggest that neurite protection alone is not sufficient to inhibit enteric neuronal degeneration in rotenone or MPP+ toxicity, and enteric neurodegeneration in PD may be occurring through independent somatic and neuritic mechanisms. Thus, therapies targeting both axonal and somal protection can be important in finding interventions for enteric symptoms in PD.
Assuntos
1-Metil-4-fenilpiridínio/toxicidade , Sistema Nervoso Entérico/efeitos dos fármacos , Degeneração Neural/induzido quimicamente , Neuritos/efeitos dos fármacos , Doença de Parkinson Secundária/induzido quimicamente , Rotenona/toxicidade , Animais , Células Cultivadas , Sistema Nervoso Entérico/patologia , Feminino , Inseticidas/toxicidade , Intoxicação por MPTP/induzido quimicamente , Intoxicação por MPTP/patologia , Camundongos , Degeneração Neural/patologia , Neuritos/patologia , Doença de Parkinson Secundária/patologia , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/patologia , GravidezRESUMO
Relata la experiencia en los hornos cementeros de Corcemar, Provincia de Córdoba en la localidad de Malagueño. Se implementa un proyecto de uso de materiales y combustibles alternativos a fin de ser utilizados en los hornos cementeros por parte de una de las empresas radicadas en la región. Dicha experiencia es el resultado de la planificación en conjunto de los sectores técnicos específicos tanto de la Municipalidad de Malagueño como de la empresa Corcemar
Assuntos
Argentina , Fornos , Incineração , Indústria do Cimento , Resíduos SólidosRESUMO
Explica que la aplicación de sistemas de alta complejidad en ingeniería ambiental permite que los residuos industriales se conviertan, incineración mediante, en combustibles alternativos para los hornos de la industria del cemento. De esta manera se reemplazan parcialmente los combustibles tradicionales como el fuel-oil o el gas.Esta práctica se presenta como solución para situaciones de conflicto producidas por la acumulación de enormes cantidades de residuos industriales en rellenos de seguridad
Assuntos
Fornos , Incineração , Indústria do CimentoRESUMO
Explica que la aplicación de sistemas de alta complejidad en ingeniería ambiental permite que los residuos industriales se conviertan, incineración mediante, en combustibles alternativos para los hornos de la industria del cemento. De esta manera se reemplazan parcialmente los combustibles tradicionales como el fuel-oil o el gas.Esta práctica se presenta como solución para situaciones de conflicto producidas por la acumulación de enormes cantidades de residuos industriales en rellenos de seguridad
Assuntos
Incineração , Fornos , Indústria do CimentoRESUMO
Relata la experiencia en los hornos cementeros de Corcemar, Provincia de Córdoba en la localidad de Malagueño. Se implementa un proyecto de uso de materiales y combustibles alternativos a fin de ser utilizados en los hornos cementeros por parte de una de las empresas radicadas en la región. Dicha experiencia es el resultado de la planificación en conjunto de los sectores técnicos específicos tanto de la Municipalidad de Malagueño como de la empresa Corcemar
Assuntos
Argentina , Resíduos Sólidos , Incineração , Fornos , Indústria do CimentoRESUMO
El objetivo del programa presentado por el autor, es la sustitución tanto de energía convencional como de de materiales para la producción de cemento. Esto implicaría un importante ahorro de energía
Assuntos
Engenharia Ambiental , Indústria do Cimento , Processamento de Resíduos Sólidos , Resíduos IndustriaisRESUMO
El objetivo del programa presentado por el autor, es la sustitución tanto de energía convencional como de de materiales para la producción de cemento. Esto implicaría un importante ahorro de energía