Experimental Cerebral Ischemia Affects the Expression of Circular RNA Genes of Metabotropic Glutamate Receptors mGluR5 and mGluR3 in Rat Brain
Circular RNAs (circRNAs) are new RNA type that show predominantly brain-specific expression pattern in mammals. Their individual representatives, acting as competitive endogenous RNAs, can bind microRNAs and contribute to the protection of functional transcripts. In the model of transient cerebral ischemia in rats, we studied the expression of glutamate metabotropic receptor genes mGluR<sub>3 </sub>and mGluR<sub>5</sub> (Grm3 and Grm5). These genes are important participants in the metabolic pathways associated with neurosignaling. In the present study, we found that rat Grm3 and Grm5 genes, in addition to mRNA, encode circRNAs, which are conserved in humans and rodents. In subcortical brain structures of rats containing a lesion focus, the level of these circRNAs is more stable than that of the corresponding mRNA. Using STarMirDB database analysis, the distribution of the mRNA binding sites along the mRNA molecules of human GRM3 and GRM5 genes which are homologous to the corresponding rat genes was elucidated. It has been revealed that sufficiently large number of binding sites is located within exons, which are also part of conservative circRNAs. The results may indicate the functional role of the circRNAs of the investigated genes as competitive endogenous RNAs in the response of brain cells to ischemia.