A NOVEL SIGNALING MECHANISM OF ANGIOTENSIN II AT 2 RECEPTORS IN NEURONAL DIFFERENTIATION.

BLANCO H; ALVAREZ SE; CIUFFO GM

Bariloche

Simposio; SISTAM 2015; 2015

In the past years it has become clear that, in addition to its cardiovascular roles, the octapeptide Angiotensin II (Ang II) has many functions in the brain by acting through two receptor subtypes, AT1 and AT2. However its role in neuronal differentiation is not well defined because is a complex process characterized by neurite outgrowth. An inducer of neuronal differentiation characteristic is nerve growth factor (NGF), NGF binding to the receptor TrKA induces differentiation by activating ERK1/2 and PI3 kinase pathway. In another research the AT2 receptor has been shown to collaborate with TrkA receptor in phosphorylation of ERK in processes of differentiation. On the other hand, In our research group, we showed a complex containing AT/SHP-1/cSrc/p85FAK, suggesting a potential role of Ang II AT2 receptors in cerebellar development. However its role in neuronal differentiation and pathway is not well defined. Thus, we decided to examine the participation of Ang II and CGP42112 (AT2 specific receptor agonist) in differentiation of SHsy5y cells. Here, we show that treatment for 3 days with either Ang II (100 nM) or CGP42112 (10 nM) induce neurite sprouting, as analyzed by optic microscopy (15-20 random fields were counted). Cells showing at least one neurite with a twofold length than the soma diameter were considered as differentiated. We explored the possible participation of PI3 kinase, MAPK and c-Src. Only cells pretreated with PP2, a c-Src family protein inhibitor, evidence a lower response to CGP41112A stimulation. Pre-treatment with Ly294002, the PI3 kinase inhibitor, or UO126, a MEK 1/2 inhibitor, did not influence the percentage of differentiation induced by CGP42112. These results suggest that activation of c-Src family protein through by stimulation of AT2 receptor modulate neuronal differentiation. To further explore the mechanism, we evaluated phosphorylation of c-SRC at residue Y 416. Src under the previous conditions, showing an early response between 0.25 min to 3 min. Besides, we also demonstrated the induction of AT receptor synthesis by stimulation of neuronal growth factor (NGF) TrkA receptors and the relation with neurite outgrowt. In summary, we demonstrated the Ang II AT2 receptors stimulation induces neuronal differentiation via activation of c-Src and the interaction between pathways of Ang II AT2 receptors and NGF.