Transcriptomic Investigation in CRISPR/Cas9-Mediated GRIK1-, GRIK2-, and GRIK4-Gene-Knockout Human Neuroblastoma Cells

The glutamate ionotropic kainate receptors, encoded by the GRIK gene family, are composed of four subunits and function as ligand-activated ion channels. They play a critical role in regulating synaptic transmission and various synaptic receptors’ processes, as well as in the pathophysiology of schizophrenia. However, their functions and mechanisms of action need to be better understood and are worthy of exploration. To further understand the exact role of the kainate receptors in vitro, we generated kainate-receptor-knockout (KO) isogenic SH-SY5Y cell lines using the CRISPR/Cas9-mediated gene editing method. We conducted RNA sequencing (RNA-seq) to determine the differentially expressed genes (DEGs) in the isogenic edited cells and used rhodamine-phalloidin staining to quantitate filamentous actin (F-actin) in differentiated edited cells. The RNA-seq and the Gene Ontology enrichment analysis revealed that the genetic deletion of the GRIK1, GRIK2, and GRIK4 genes disturbed multiple genes involved in numerous signal pathways, including a converging pathway related to the synaptic membrane. An enrichment analysis of gene–disease associations indicated that DEGs in the edited cell lines were associated with several neuropsychiatric disorders, especially schizophrenia. In the morphology study, fluorescent images show that less F-actin was expressed in differentiated SH-SY5Y cells with GRIK1, GRIK2, or GRIK4 deficiency than wild-type cells. Our data indicate that kainate receptor deficiency might disturb synaptic-membrane-associated genes, and elucidating these genes should shed some light on the pathophysiology of schizophrenia. Furthermore, the transcriptomic profiles for kainate receptor deficiency of SH-SY5Y cells contribute to emerging evidence for the novel mechanisms underlying the effect of kainate receptors and the pathophysiology of schizophrenia. In addition, our data suggest that kainate-receptor-mediated F-actin remodeling may be a candidate mechanism underlying schizophrenia.