Molecular Correlates of Topiramate and GRIK1 rs2832407 Genotype in Pluripotent Stem Cell–Derived Neural Cultures

Abstract

There is growing evidence that the anticonvulsant topiramate is efficacious in reducing alcohol consumption.Further, an intronic single nucleotide polymorphism (rs2832407, C ! A) in the GRIK1 gene, which encodes the GluK1 subunit of the excitatory kainate receptor, predicted topiramate's effectiveness in reducing heavy drinking in a clinical trial. In the current study, we differentiated a total of 22 induced pluripotent stem cell (iPSCs) lines characterized by GRIK1 rs2832407 genotype (10 A/A and 12 C/C) into forebrain-lineage neural cultures to explore molecular correlates of GRIK1 genotype that may relate to topiramate's ability to reduce drinking. Our differentiation protocol yielded mixed neural cultures enriched for glutamatergic neurons. Characterization of the GRIK1 locus revealed no effect of rs2832407 genotype on GRIK1 isoform mRNA expression, however a significant difference was observed on GRIK1 antisense-2, with higher expression in C/C neural cultures. Differential effects of acute exposure to 5 μM topiramate were observed on the frequency of spontaneous synaptic activity in A/A vs. C/C neurons, with a smaller reduction in excitatory event frequency and a greater reduction in inhibitory event frequency observed in C/C donor neurons.This work highlights the use of iPSC technologies to study pharmacogenetic treatment effects in psychiatric disorders and furthers our understanding of the molecular effects of topiramate exposure in human neural cells.

Induced pluripotent stem cell reprogramming‐associated methylation at the GABRA2 promoter and chr4p12 GABAA subunit gene expression in the context of alcohol use disorder

“…Mature cultures, operationally defined as 12 weeks post neural cell plating, contain a mixture of neurons and glial cells. With this protocol, approximately 50% of cells show immunostaining for the glutamatergic neuron transcription factor TBR1 and 25% for GABA‐ergic markers (Fink et al, 2017; Lieberman et al, 2020; Lieberman, Kranzler, Levine, & Covault, 2018). Neurons in these cultures demonstrate spontaneous synaptic activity, functional ionotropic GABA A and glutamatergic receptors, and an ability to generate trains of action potentials in response to current injection (Lieberman et al, 2012) Fink et al, 2017; Lieberman et al, 2020).…”

“…With this protocol, approximately 50% of cells show immunostaining for the glutamatergic neuron transcription factor TBR1 and 25% for GABA‐ergic markers (Fink et al, 2017; Lieberman et al, 2020; Lieberman, Kranzler, Levine, & Covault, 2018). Neurons in these cultures demonstrate spontaneous synaptic activity, functional ionotropic GABA A and glutamatergic receptors, and an ability to generate trains of action potentials in response to current injection (Lieberman et al, 2012) Fink et al, 2017; Lieberman et al, 2020). A comparison of transcriptome profiles for human iPSC‐derived forebrain lineage neural cultures and human postmortem brain tissue indicated that 12‐week iPSC‐derived neural cultures are most similar to that of first trimester forebrain tissue (Brennand et al, 2015; Mariani et al, 2012).…”

Alterations in Neurotrophins in Alcohol-Addicted Patients during Alcohol Withdrawal

“…Alcohol use disorder (AUD) is associated with behavioral, cognitive, and physiological symptoms, including a strong need to consume alcohol, decreased control over use, use despite harmful consequences, social impairment, risky use patterns, and physiologic tolerance and withdrawal [ 1 , 2 , 3 ]. AUD is the most commonly diagnosed addiction.…”