RESUMO
The molecular mechanisms that generate dendrites in the CNS are poorly understood. The diffusible signal molecule Slit and the neuronally expressed receptor Robo mediate growth cone collapse in vivo. However, in cultured neurons, these molecules promote dendritic development. Here we examine the aCC motoneuron, one of the first CNS neurons to generate dendrites in Drosophila. Slit displays a dynamic concentration topography that prefigures aCC dendrogenesis. Genetic deletion of Slit leads to complete loss of aCC dendrites. Robo is cell-autonomously required in aCC motoneurons to develop dendrites. Our results demonstrate that Slit and Robo control the development of dendrites in the embryonic CNS.
Assuntos
Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo , Dendritos/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas do Tecido Nervoso/metabolismo , Receptores Imunológicos/metabolismo , Animais , Sistema Nervoso Central/embriologia , Proteínas de Drosophila/genética , Drosophila melanogaster/embriologia , Mutação/genética , Proteínas do Tecido Nervoso/genética , Receptores Imunológicos/genética , Proteínas RoundaboutRESUMO
Understanding the establishment of functional neuronetworks is one of the frontiers of developmental neurobiology. The use of axons and dendrites from Drosophila nervous system as a model allows the identification of molecular mechanisms which give neurons the ability to guide their processes en route to connect precisely with their partners. By focusing on selected Drosophila model systems, we discuss the recent advances in our understanding of the molecular mechanisms regulating guidance, branching and targeting of axons and dendrites required for the establishment of a functional neuronetwork.
Assuntos
Drosophila/fisiologia , Rede Nervosa/embriologia , Neurônios/fisiologia , Animais , Axônios/fisiologia , Dendritos/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Rede Nervosa/citologia , Fenômenos Fisiológicos do Sistema Nervoso , Junção Neuromuscular/fisiologia , Neurônios/citologia , Células Fotorreceptoras de Invertebrados/fisiologiaRESUMO
Neuronal connectivity is established by the axo-dendritic polarity, correct guidance and targeting of neurons. Unlike for axons, the mechanisms responsible for directed outgrowth of dendrites are not well understood. Using single-cell labeling, we describe specific guidance defects in dendrites of identified neurons in frazzled, robo, netrin and commissureless mutant embryos of Drosophila melanogaster. We found that the cell-surface molecules Frazzled and Robo work as guidance molecules not only for axons but also for dendrites as they navigate within the CNS. Furthermore, we report that each neuron showed a cell-autonomous and independent use of guidance molecules.