BE-63 Impacts of upregulating miR-718 on neural activity

Autism Spectrum Disorder (ASD) is a category of neurodevelopmental disorders that possess a range of symptoms, some of the more hallmark traits involving social delays and strict, repetitive interests and behaviors. There’s no known cause at this time; however, some hypothesize that altered levels of amino acids (e.g. glutamate) and epigenetics could play a major part. Epigenetic factors encompass mechanisms that can alter gene expression without altering gene sequences. These factors include DNA methylation, histone modifications, and non-coding RNA, namely microRNAs (miRNA). MiRNAs repress gene expression by binding to mRNA to cause degradation of the mRNA, preventing expression of the protein. Specifically, miR-718 has been known to alter the autophagy pathway through targeting phosphatase and tensin Homolog (PTEN) mRNA for degradation. PTEN alterations have not only been implicated in ASD, but in some types of cancers as well. PTEN dysregulation can prevent proper transport of glutamine into transport vesicles in neurons by solute carrier proteins (SLC proteins) in a process known as glutaminolysis. Deficits in glutaminolysis could be due to the SLC protein SLC6A20 as it is a suspected target of miR-718. Further, SLC6A20 regulates homeostasis of glycine and proline. Imbalances of glycine can disrupt the proper functioning of a major glutamate receptor known as the NMDA receptor (NMDAR), which is also seen in patients with ASD. This may implicate miR-718 not only in glutamate and SLC6A20 dysregulation, but also improper glycine and NMDAR functioning. Therefore, we sought to explore the effects of upregulating miR-718 on SLC6A20 expression and NMDAR functioning. We hypothesized that an upregulation of miR-718 will lead to a decrease in SLC6A20 and therefore a loss in glutamate signaling. We tested our hypothesis through RT-qPCR and multielectrode array studies. Completed work shows miR-718 does target SLC6A20 mRNA for degradation, and miR-718 upregulation disrupts membrane activity and voltage.