RESUMO
Dendritic spines are the postsynaptic structure to mediate signal transduction in neural circuitry, whose function and plasticity are regulated by organization of their molecular architecture and by the expression of target genes and proteins. EphB2, a member of the Eph receptor tyrosine kinase family, potentiates dendritic spine maturation through cytoskeleton reorganization and protein trafficking. However, the transcriptional mechanisms underlying prolonged activation of EphB2 signaling during dendritic spine morphogenesis are unknown. Herein, we performed transcriptional profiling by stimulating EphB2 signaling and identified differentially expressed genes implicated in pivotal roles at synapses. Notably, we characterized an F-actin binding protein, Annexin A1, whose expression was induced by EphB2 signaling; the promotor activity of its coding gene Anxa1 is regulated by the activity of CREB (cAMP-response element-binding protein). Knockdown of Annexin A1 led to a significant reduction of mature dendritic spines without an obvious deficit in the complexity of dendrites. Altogether, our findings suggest that EphB2-induced, CREB-dependent Annexin A1 expression plays a key role in regulating dendritic spine morphology.
Assuntos
Anexina A1/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Espinhas Dendríticas/genética , Receptor EphB2/genética , Anexina A1/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Espinhas Dendríticas/fisiologia , Perfilação da Expressão Gênica/métodos , Ontologia Genética , Redes Reguladoras de Genes/genética , Células HEK293 , Humanos , Microscopia Confocal , Morfogênese/genética , Neurônios/metabolismo , Mapas de Interação de Proteínas/genética , RNA-Seq/métodos , Receptor EphB2/metabolismo , Transdução de Sinais/genética , Sinapses/genética , Sinapses/fisiologiaRESUMO
Cytoskeletal remodeling is indispensable for the development and maintenance of neuronal structures and functions. However, the molecular machinery that controls the balance between actin polymerization and depolymerization during these processes is incompletely understood. Here, we report that coronin 2B, a conserved actin-binding protein, is concentrated at the tips of developing dendrites and that knockdown of coronin 2B inhibits the growth of dendrites. Importantly, coronin 2B interacts with actin and reduces the F-actin/G-actin ratio. Furthermore, the coiled-coil domain of coronin 2B is required for its oligomerization, thus confining coronin 2B to neurite tips. Our findings collectively suggest that coronin 2B is important for promoting dendrite outgrowth by limiting the speed of actin polymerization at growth cones.
Assuntos
Actinas/metabolismo , Cones de Crescimento/metabolismo , Proteínas dos Microfilamentos/metabolismo , Actinas/química , Actinas/genética , Animais , Citoesqueleto/química , Citoesqueleto/genética , Citoesqueleto/metabolismo , Cones de Crescimento/química , Células HEK293 , Humanos , Camundongos , Proteínas dos Microfilamentos/química , Proteínas dos Microfilamentos/genética , Domínios ProteicosRESUMO
Alzheimer's disease is an irreversible neurodegenerative disorder for which we have limited knowledge of the mechanisms underlying its pathogenesis, especially the molecular events that trigger the deterioration of neuronal functions in the early stage. Protein phosphorylation and dephosphorylation are highly dynamic and reversible post-translational modifications that control protein signaling and hence neuronal functions, aberrations of which are implicated in various neurodegenerative diseases including Alzheimer's disease. We conducted a quantitative phosphoproteomic analysis in the brains of APP/PS1 mice, an Aß-deposition transgenic mouse model, at 3 months old, the stage at which amyloid pathology just initiates. Compared to the wild-type mouse brains, we found that changes in serine phosphorylation were predominant in the APP/PS1 mouse brains, and that the occurrence of proline-directed phosphorylation was most common among the overrepresented phosphopeptides. Further analysis of the 167 phosphoproteins that were significantly up- or downregulated in APP/PS1 mouse brains revealed the enrichment of these proteins in synapse-related pathways. In particular, Western blot analysis validated the increased phosphorylation of chromogranin B, a protein enriched in large dense-core vesicles, in APP/PS1 mouse brains. These findings collectively suggest that changes in the phosphoprotein network may be associated with the deregulation of synaptic functions during the pathogenesis of Alzheimer's disease.