REGULATION OF TYPE 1 EQUILIBRATIVE NUCLEOSIDE TRANSPORTER BY MICRORNA-124.

Adenosine is a neuromodulator found in several areas of the Central Nervous System (CNS), and it is fundamental in several physiological and pathological events. It acts through the interaction with its receptors, which are divided in 4 subtypes: A1, A2A, A2B and A3, all of them are G protein-coupled receptors. Its transport through the membrane is regulated by transmembrane proteins called equilibrative nucleoside transporters (ENTs), which were described in CNS into four isoforms, with ENT1/ENT2 being the predominant ones. They are classified according to their sensitivity to the compound nitrobenzylthioinosine (NBTI), ENT1 being sensitive to nanomolar concentrations of NBI, and ENT2, insensitive to these concentrations. ENT1 is also much more expressed in the plasma membrane than ENT2. MicroRNAs are a group of non-coding RNAs that have been shown to play an important regulatory role, they act by a interaction with mRNA targets interrupting the translation mechanism. A possible endogenous source of microRNAs would be the exosomes, that are small extracellular vesicles of endocytic origin produced in different CNS cell types, serving as a mechanism of cargo diffusion to another cells and tissues.