Anales RANF

S15-02 CORTICAL NEURONAL MIGRATION ENTAILS A2A RECEPTOR-DRIVEN NEURONAL POLARIZATION AND AXON FORMATION S. Alçada-Morais 1,2 , , V. Moreno-Juan 3 , N. Gonçalves 1 , J. M. Marques 1 , B. Andres 3 , S. Ferreira 1,2 , J. M. M. Rocha 1 , X. Xu 1,2 , R. A. Cunha 1,4 , G. López-Bendito 3 , R. J. Rodrigues 1 1 . Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; 2 . Instituto de Investigação Interdisciplinar, University of Coimbra, Coimbra, Portugal; 3 . Instituto de Neurociencias de Alicante, CSIC-UMH, Spain; 4 . Faculty of Medicine, University of Coimbra, Coimbra, Portugal. Neuronal migration is fundamental for the formation of the brain cytoarchitecture. Any defect in this process may have long-term deleterious effects ranging from mild cognitive impairment, to severe neurological and psychiatric conditions. (Neuron 60:273). It was recently shown that adenosine A2AR controls interneurons migration (Sci. Trans. Med. 5:197ra104). We now aimed to evaluate if A2AR is also involved in the migration of cortical principal neurons. We observed that mice embryos lacking the A2AR (A2AR-KO) displayed a delayed migration at E17.5 of cortical principal neurons labelled with BrdU at E14.5, in comparison with wild-type littermates. Similarly, mice embryos exposed to the A2AR antagonist SCH58261 (daily 0.1 mg/kg i.p. injection in pregnant females E13.5-E16.5) also displayed delayed migration. This should be due to A2ARs expressed by migratory neurons since in utero electroporation of a plasmid encoding shRNA for A2AR (E14.5-E17.5) also delayed migration. This delay or accumulation of a subset of neurons occurs mostly at the lower intermediate zone (IZ), where it is required a multipolar-bipolar transition and the establishment of an axon-like process in their migration towards the cortical plate (CP) (Nat. Neurosci. 12:1693). Accordingly, mice primary cortical neurons cultured in the presence of the A2AR antagonist SCH58261 (50 nM) either were unable to form an axon or displayed a reduced axonal length. Similarly, the knockdown of A2ARs in the migratory neurons leads to an impairment both in neuronal polarization and axon formation at the IZ. Moreover, we observed in embryos lacking ecto-5’-nucleotidase (CD73-KO mice), the enzyme that catabolizes AMP into adenosine and fundamental for the formation of ATP-derived adenosine, an accumulation of neurons also in the lower IZ (E14.5-E17.5). Accordingly, we detected immunoreactivity for the vesicular nucleotide transporter in the developing mice cortex at E13-E17. both in neurons and glial cells, indicating that they are endowed with the machinery to release ATP. Altogether, these results show that A2ARs activated by ATP-derived adenosine are required for cortical principal neuronal migration, in particular for the transition from the IZ into the CP by controlling the establishment of neuronal polarity and axon formation. Funding: EXPL/NEU-NMC/0671/2012; PTDC/NEU-NMC/3567/2014; POCI-01-0145- FEDER-007440;CENTRO-01-0145-FEDER-000008:BrainHealth 2020; PTDC/MED- NEU/28160/2017