IMBICE   05372
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA CELULAR
Unidad Ejecutora - UE
libros
Título:
Great points of axon guidance and ordered connections
Autor/es:
GABRIEL SCICOLONE; ANA LAURA ORTALLI; NESTOR GABRIEL CARRI
Editorial:
Version ON-LINE en 2008 IMBICE
Referencias:
Lugar: La Plata; Año: 2008 p. 166
Resumen:
The study of cellular and molecular mechanisms involved in the development of topographic ordered connections in the central nervous system (CNS) is a key issue in neurobiology because neural connectivities constitute the base of the CNS normal function. Axonal growth cones are the sensory-motor structures that are guided by molecular cues toward their appropriate target. Asymmetric activation of receptors and signaling pathways in the growth cones directs the remodeling of cytoskeleton, plasma membrane, extracellular matrix and focal adhesions giving directionality to neurite outgrowth. The expression pattern of Eph-ephrin system in opposing gradients both in the retina and the tectum, labels the local addresses on the target surface and gives specific sensitivities to growth cones according to their topographic origin in the retina. Since Ephs and ephrins are membrane attached molecules, they may function as receptors or ligands producing repulsive or attractant responses according to their microenvironmental context. Ephs and ephrins play central roles from axon guidance to synapse formation and remodeling, showing high functional versatility. Besides, other molecules play redundant functions in these processes. Interaxonal competition is another mechanism involved in connection refinement. Studies in this experimental model support general principles for understanding CNS development, but some contradictory results, due to differences among species and the employment of different experimental approaches, should be reanalyzed. Finally, the spatiotemporal expression of Eph-ephrin system appears to play a role in regeneration failure in adult mammalian CNS. Thus, the manipulation of this molecular system could be useful for developing regeneration therapies.