Assuntos
Envelhecimento/fisiologia , Glutamatos/fisiologia , Habituação Psicofisiológica/fisiologia , Aprendizagem em Labirinto/fisiologia , Neurônios/fisiologia , Receptor CB1 de Canabinoide/fisiologia , Animais , Deficiências da Aprendizagem/genética , Deficiências da Aprendizagem/psicologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Desempenho Psicomotor/fisiologia , Receptor CB1 de Canabinoide/genética , Memória EspacialRESUMO
The transcription factors TBX2 and TBX3 are overexpressed in various human cancers. Here, we investigated the effect of overexpressing the orthologous Tbx genes Drosophila optomotor-blind (omb) and human TBX2 in the epithelium of the Drosophila wing imaginal disc and observed two types of cell motility. Omb/TBX2 overexpressing cells could move within the plane of the epithelium. Invasive cells migrated long-distance as single cells retaining or regaining normal cell shape and apico-basal polarity in spite of attenuated apical DE-cadherin concentration. Inappropriate levels of DE-cadherin were sufficient to drive cell migration in the wing disc epithelium. Omb/TBX2 overexpression and reduced DE-cadherin-dependent adhesion caused the formation of actin-rich lateral cell protrusions. Omb/TBX2 overexpressing cells could also delaminate basally, penetrating the basal lamina, however, without degradation of extracellular matrix. Expression of Timp, an inhibitor of matrix metalloproteases, blocked neither intraepithelial motility nor basal extrusion. Our results reveal an MMP-independent mechanism of cell invasion and suggest a conserved role of Tbx2-related proteins in cell invasion and metastasis-related processes.
Assuntos
Movimento Celular/fisiologia , Proteínas de Drosophila/metabolismo , Células Epiteliais/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas com Domínio T/metabolismo , Animais , Animais Geneticamente Modificados , Drosophila , Proteínas de Drosophila/genética , Humanos , Imuno-Histoquímica , Hibridização In Situ , Metaloproteinases da Matriz/metabolismo , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Proteínas do Tecido Nervoso/genética , Proteínas com Domínio T/genéticaRESUMO
Brain aging is associated with cognitive decline that is accompanied by progressive neuroinflammatory changes. The endocannabinoid system (ECS) is involved in the regulation of glial activity and influences the progression of age-related learning and memory deficits. Mice lacking the Cnr1 gene (Cnr1(-/-)), which encodes the cannabinoid receptor 1 (CB1), showed an accelerated age-dependent deficit in spatial learning accompanied by a loss of principal neurons in the hippocampus. The age-dependent decrease in neuronal numbers in Cnr1(-/-) mice was not related to decreased neurogenesis or to epileptic seizures. However, enhanced neuroinflammation characterized by an increased density of astrocytes and activated microglia as well as an enhanced expression of the inflammatory cytokine IL-6 during aging was present in the hippocampus of Cnr1(-/-) mice. The ongoing process of pyramidal cell degeneration and neuroinflammation can exacerbate each other and both contribute to the cognitive deficits. Deletion of CB1 receptors from the forebrain GABAergic, but not from the glutamatergic neurons, led to a similar neuronal loss and increased neuroinflammation in the hippocampus as observed in animals lacking CB1 receptors in all cells. Our results suggest that CB1 receptor activity on hippocampal GABAergic neurons protects against age-dependent cognitive decline by reducing pyramidal cell degeneration and neuroinflammation.
