MiR-718 Impacts Expression of Solute Carriers in SH-SY5Y Cells

MicroRNAs (miRNA) are emerging as a vital topic in molecular biology, as the role that they play in affecting gene regulation is beginning to be more understood. MicroRNAs are small, non-coding sequences of RNA that are never made into protein. MicroRNAs bind to a multiprotein complex, RNA-induced silencing complex (RISC), that degrades mRNA sequences. A single microRNA can have many different target genes and influence their expression. In prior studies, targets of miR-718 were downregulated when miR-718 was upregulated, causing modulation of signaling pathways. In particular, upregulation of miR-718 was associated with an unfavorable prognosis in some cancer types through affecting PTEN expression. Therefore, our lab is interested in miR-718’s effects on neuron structure and behavior since PTEN regulates autophagy and dendritic spine formation in neural cells. Upon investigating miR-718’s theoretical targets in TargetScan.org, we noted that miR-718 is predicted to target many genes that affect cell communication and neuronal signaling, including 13 solute carrier genes and 2 genes that impact neurotransmission. Therefore, we wanted to determine if miRNA-718 expression affects these solute carriers and neurotransmission genes. Solute carriers are responsible for allowing neurons to communicate with each other. If there is a downregulation in the solute carrier targets and/or neurotransmission-related targets of miR-718, then the neurons will not be able to communicate as effectively, if at all. We started by growing a human neuronal cell line called SH-SY5Y (a human neuronal model) and either controlled for miR-718 expression or upregulated miR-718 expression via RNA interference (RNAi) using siRNAs. We then isolated RNA by Trizol extraction, performed cDNA synthesis, and ran qPCR tests to determine the level of solute carriers and neurotransmission-related genes. We found that out of 13 solute carriers tested, 8 were significantly downregulated when treated with miR-718. For 5 of the solute carriers, we could not determine if their expression was impacted because they were not highly expressed in the neuronal cell line. The 2 neurotransmission-related genes were also significantly downregulated upon increasing miR-718. This could be applicable in future research when trying to understand neurodevelopmental disorders such as autism spectrum disorders (ASD) that are impacted by neuronal communication. In future studies, we plan to confirm using individual Taqman assays on other cell types to determine how miR-718 affects the unexpressed solute carriers’ expression levels.