RESUMO
The architecture of the neurovascular unit (NVU) is controlled by the communication of neurons, glia, and vascular cells. We found that the neuronal guidance cue reelin possesses proangiogenic activities that ensure the communication of endothelial cells (ECs) with the glia to control neuronal migration and the establishment of the blood-brain barrier in the mouse brain. Apolipoprotein E receptor 2 (ApoER2) and Disabled1 (Dab1) expressed in ECs are required for vascularization of the retina and the cerebral cortex. Deletion of Dab1 in ECs leads to a reduced secretion of laminin-α4 and decreased activation of integrin-ß1 in glial cells, which in turn control neuronal migration and barrier properties of the NVU. Thus, reelin signaling in the endothelium is an instructive and integrative cue essential for neuro-glia-vascular communication.
Assuntos
Comunicação Celular , Córtex Cerebral/irrigação sanguínea , Endotélio Vascular/fisiologia , Neovascularização Fisiológica , Proteínas do Tecido Nervoso/metabolismo , Neuroglia/fisiologia , Neurônios/fisiologia , Vasos Retinianos/fisiologia , Animais , Barreira Hematoencefálica/citologia , Barreira Hematoencefálica/fisiologia , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Movimento Celular , Endotélio Vascular/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Feminino , Deleção de Genes , Integrina beta1/metabolismo , Proteínas Relacionadas a Receptor de LDL/genética , Proteínas Relacionadas a Receptor de LDL/metabolismo , Laminina/metabolismo , Masculino , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Neuroglia/citologia , Neuroglia/metabolismo , Neurônios/metabolismo , Proteína Reelina , Vasos Retinianos/citologia , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Transdução de SinaisRESUMO
FLRTs are broadly expressed proteins with the unique property of acting as homophilic cell adhesion molecules and as heterophilic repulsive ligands of Unc5/Netrin receptors. How these functions direct cell behavior and the molecular mechanisms involved remain largely unclear. Here we use X-ray crystallography to reveal the distinct structural bases for FLRT-mediated cell adhesion and repulsion in neurons. We apply this knowledge to elucidate FLRT functions during cortical development. We show that FLRTs regulate both the radial migration of pyramidal neurons, as well as their tangential spread. Mechanistically, radial migration is controlled by repulsive FLRT2-Unc5D interactions, while spatial organization in the tangential axis involves adhesive FLRT-FLRT interactions. Further, we show that the fundamental mechanisms of FLRT adhesion and repulsion are conserved between neurons and vascular endothelial cells. Our results reveal FLRTs as powerful guidance factors with structurally encoded repulsive and adhesive surfaces.
Assuntos
Proteínas de Membrana/química , Neurônios/metabolismo , Animais , Adesão Celular , Cristalografia por Raios X/métodos , Glicosaminoglicanos/metabolismo , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Mutação/genética , RatosRESUMO
Moderate, transient oxidative stress is achieved in SH-SY5Y cells using tertiary butylhydroperoxide as oxidant. Over a recovery period of 24 h, the enzymatic activity and protein levels of the acetylcholinesterase (AChE) splice variants tailed AChE (AChE-T) and readthrough AChE (AChE-R) are monitored. Their time-dependent correlation to pro- and anti-apoptotic factors, namely caspase 3 and Bcl-2, respectively, as well as lactate dehydrogenase release as a measure of cell viability is assessed. A distinctly different expression pattern of AChE-T as compared with AChE-R is recorded, in that AChE-T shows only a very slight increase over a 6 h time period. In contrast, AChE-R rises continuously during the recovery period, reaching peak intracellular levels that are up to six times higher than control levels 3-4 h post-stress, and is released from cells in substantial amounts. Moreover, anti-apoptotic Bcl-2 increases significantly, peaking 2-3 h after this AChE-R peak has occurred. We believe this study presents the first work that demonstrates - without relying on techniques of over-expression - the time-dependent correlation between apoptotic processes and related rescue mechanisms involving AChE isoforms in a neuronal cell line.