Patrícia Sofia Alçada Tomás de Morais - CNC, University of Coimbra
Title: CORTICAL NEURONAL MIGRATION ENTAILS A2A RECEPTOR-DRIVEN NEURONAL POLARIZATION AND AXON FORMATION
Abstract:
Neuronal migration is a fundamental process in brain development. Indeed, impairment in neuronal migration is one of the major causes of cortical malformation, which has been associated to several neurological and psychiatric disorders [1]. Hence, it is of upmost importance to unravel the mechanisms driving neuronal migration. In this regard, it was recently shown that adenosine A2AR controls interneurons migration [2]. We now aimed to evaluate if A2AR is also involved in the migration of cortical principal neurons. For that purpose, we first evaluated the impact of the genetic deletion (A2AR KO) or the pharmacological blockade of A2AR on mice cortical neurons migration during embryonic development. In comparison to their wild-type littermates, embryos lacking the A2AR showed a delayed migration of cortical principal neurons at embryonic day 17 (E17). Similarly, embryos exposed to the A2AR antagonist SCH58261 (daily 0.1mg/kg i.p. injection in pregnant females from E13 to E16) have shown delayed migration, when compared with embryos exposed to vehicle. This should be due to A2ARs expressed by migratory neurons since in utero electroporation of a plasmid encoding shRNA specific for A2AR (E14- E17) also delays migration. The neuronal migration delay occurs mostly in the intermediate zone, where it was observed an accumulation of neurons. It is well-known that it is required a transition from a multipolar to a bipolar shape at the intermediate zone and the establishment of an axon-like leading process in order to the neurons to proceed their migration into the cortical plate [3]. Accordingly, we found in mice cortical neurons that the pharmacological blockade of A2AR with the selective antagonist SCH58261 (50 nM) leads to a reduction in the number of axons (SMI-31 positive neurites) and in their length (DIV 0-3), and we could observe that the knockdown of A2ARs leads to an impairment both in neuronal polarization and axon formation in the migratory neurons. Finally, the observation of a similar delayed cortical principal neurons migration in the CD73-KO mice, which lacks the ecto-5’-nucleotidase that converts AMP into adenosine, indicates that the adenosine that is activating the A2ARs derives from the extracellular catabolism of ATP. This is further heralded by the observation of immunoreactivity for the vesicular nucleotide transporter in the developing mice cortex at E13-E17. 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 intermediate zone into the cortical plate by controlling the establishment of neuronal polarity and axon formation.
Title: CORTICAL NEURONAL MIGRATION ENTAILS A2A RECEPTOR-DRIVEN NEURONAL POLARIZATION AND AXON FORMATION
Abstract:
Neuronal migration is a fundamental process in brain development. Indeed, impairment in neuronal migration is one of the major causes of cortical malformation, which has been associated to several neurological and psychiatric disorders [1]. Hence, it is of upmost importance to unravel the mechanisms driving neuronal migration. In this regard, it was recently shown that adenosine A2AR controls interneurons migration [2]. We now aimed to evaluate if A2AR is also involved in the migration of cortical principal neurons. For that purpose, we first evaluated the impact of the genetic deletion (A2AR KO) or the pharmacological blockade of A2AR on mice cortical neurons migration during embryonic development. In comparison to their wild-type littermates, embryos lacking the A2AR showed a delayed migration of cortical principal neurons at embryonic day 17 (E17). Similarly, embryos exposed to the A2AR antagonist SCH58261 (daily 0.1mg/kg i.p. injection in pregnant females from E13 to E16) have shown delayed migration, when compared with embryos exposed to vehicle. This should be due to A2ARs expressed by migratory neurons since in utero electroporation of a plasmid encoding shRNA specific for A2AR (E14- E17) also delays migration. The neuronal migration delay occurs mostly in the intermediate zone, where it was observed an accumulation of neurons. It is well-known that it is required a transition from a multipolar to a bipolar shape at the intermediate zone and the establishment of an axon-like leading process in order to the neurons to proceed their migration into the cortical plate [3]. Accordingly, we found in mice cortical neurons that the pharmacological blockade of A2AR with the selective antagonist SCH58261 (50 nM) leads to a reduction in the number of axons (SMI-31 positive neurites) and in their length (DIV 0-3), and we could observe that the knockdown of A2ARs leads to an impairment both in neuronal polarization and axon formation in the migratory neurons. Finally, the observation of a similar delayed cortical principal neurons migration in the CD73-KO mice, which lacks the ecto-5’-nucleotidase that converts AMP into adenosine, indicates that the adenosine that is activating the A2ARs derives from the extracellular catabolism of ATP. This is further heralded by the observation of immunoreactivity for the vesicular nucleotide transporter in the developing mice cortex at E13-E17. 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 intermediate zone into the cortical plate by controlling the establishment of neuronal polarity and axon formation.