Microtubule associated protein (MAP1B) is involved in dendritic spine development and neurotransmission.

CAROLINA MONTENEGRO-VENEGAS; MARIANO BISBAL; LAURA GASTALDI; ELENA TORTOSA; STEFFEN HARTEL; JOSE ESTEBAN; ALFREDO CACERES; JESUS AVILA; CHRITIAN GONZALEZ-BILLAULT

Santa Cruz

Workshop; EMERGING CONCEPTS ON NEURONAL CYTOSKELETON; 2011

Universidad de Chile

AbstractMicrotubule-associated protein 1B (MAP1B) is predominantly expressed during the early stages of neuronal development. Later, its expression becomes developmentally down-regulated until it almost disappears, however it expression remain increased in adult brain areas of high synaptic plasticity such as the hippocampus and cerebellum. For such a reason we hypothesized that it may have a role in the control of synapses. MAP1B encodes two polypeptides, the heavy chain and the light chain 1 (LC1). Using the yeast two hybrid (Y2H) approaches we were able to pull down some LC1 interacting partners from an adult mice brain genomic library. In this work we describe the interaction between MAP1B and Snapin, a soluble protein associated with synaptic vesicles. Additionally we determine that the kinetic of vesicle release is decreased in MAP1B-/- neurons, suggesting a possible role for MAP1B at the pre-synaptic level. On the other hand, we observed the presence of MAP1B in dendritic spines and synaptosomal fractions of wild type adult mice. Neurons derived from MAP1B-deficient mice showed a decrease in the density of mature dendritic spines and an increase of immature filopodia-like protrusions. In addition, these neurons showed a significant decrease in their synaptic currents mediated by AMPA receptors. Moreover, using post-synaptic densities from adult MAP1B +/- mice, we show a significant decrease in Rac1 activity and an increase in RhoA activity. These MAP1B +/- fractions present a decrease in phosphorylated cofilin. Taken together, these results define a new and important fraction of MAP1B in dendritic spine formation and maturation through the regulation of actin cytoskeleton at the post-synaptic level. Therefore, MAP1B could regulate neural transmission at both the pre- or/and post-synaptic level. tipo de presentación: comunicación oral