Functional polymorphisms and transcriptional analysis in the 5' region of the human serotonin receptor 1B gene (HTR1B) and their associations with psychiatric disorders

Understanding the Molecular Regulation of Serotonin Receptor 5-HTR1B-β-Arrestin1 Complex in Stress and Anxiety Disorders

The serotonin receptor subtype 5-HTR1B is widely distributed in the brain with an important role in various behavioral implications including neurological conditions and psychiatric disorders. The neuromodulatory action of 5-HTR1B largely depends upon its arrestin mediated signaling pathway. In this study, we tried to investigate the role of unusually long intracellular loop 3 (ICL3) region of the serotonin receptor 5-HTR1B in interaction with β-arrestin1 (Arr2) to compensate for the absence of the long cytoplasmic tail. Molecular modeling and docking tools were employed to obtain a suitable molecular conformation of the ICL3 region in complex with Arr2 which dictates the specific complex formation of 5-HTR1B with Arr2. This reveals the novel molecular mechanism of phosphorylated ICL3 mediated GPCR-arrestin interaction in the absence of the long cytoplasmic tail. The in-cell disulfide cross-linking experiments and molecular dynamics simulations of the complex further validate the model of 5-HTR1B-ICL3-Arr2 complex. Two serine residues (Ser281 and Ser295) within the 5-HTR1B-ICL3 region were found to be occupying the electropositive pocket of Arr2 in our model and might be crucial for phosphorylation and specific Arr2 binding. The alignment studies of these residues showed them to be conserved only across 5-HTR1B mammalian species. Thus, our studies were able to predict a molecular conformation of 5-HTR1B-Arr2 and identify the role of long ICL3 in the signaling process which might be crucial in designing targeted drugs (biased agonists) that promote GPCR-Arr2 signaling to deter the effects of stress and anxiety-like disorders.

Single-Nucleotide Polymorphisms as Biomarkers of Antipsychotic-Induced Akathisia: Systematic Review

Antipsychotic-induced akathisia (AIA) is a movement disorder characterized by a subjective feeling of inner restlessness or nervousness with an irresistible urge to move, resulting in repetitive movements of the limbs and torso, while taking antipsychotics (APs). In recent years, there have been some associative genetic studies of the predisposition to the development of AIA. Objective: The goal of our study was to review the results of associative genetic and genome-wide studies and to systematize and update the knowledge on the genetic predictors of AIA in patients with schizophrenia (Sch). Methods: We searched full-text publications in PubMed, Web of Science, Springer, Google Scholar, and e-Library databases from 1977 to 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) quality scale was used for the critical selection of the studies. Results: We identified 37 articles, of which 3 were included in the review. Thus, the C allele of rs1800498 (59414 C>T) and the A allele of rs1800497 (17316 G>A) (TaqIA) from the DRD2 gene as well as the TT genotype rs13212041 (77461407 C>T) from the HTR1B gene were found to be associated with AIA. Conclusions: Uncovering the genetic biomarkers of AIA may provide a key to developing a strategy for the personalized prevention and treatment of this adverse neurological drug reaction of APs in patients with Sch in real clinical practice.

The effect of human GRIN1 gene 5' functional region on gene expression regulation in vitro

INTRODUCTION

Abnormal expression of ionotropic glutamate receptor NMDA type subunit 1, the key subunit of the NMDA receptor, may be related to many neuropsychiatric disorders. In this study, we explored the functional sequence of the 5' regulatory region of the human GRIN1 gene and discussed the transcription factors that may regulate gene expression.

MATERIALS AND METHODS

Twelve recombinant pGL3 vectors with gradually truncated fragment lengths were constructed, transfected into HEK-293, U87, and SK-N-SH cell lines, and analyzed through the luciferase reporter gene assay. JASPAR database is used to predict transcription factors.

RESULTS

In SK-N-SH and U87 cell lines, regions from -337 to -159 bp, -704 to -556 bp inhibited gene expression, while -556 to -337 bp upregulated gene expression. In HEK-293 and U87 cell lines, the expression of fragment -1703 to + 188 bp was significantly increased compared to adjacent fragments -1539 to + 188 bp and -1843 to + 188 bp. The protein expressions of fragments -2162 to + 188 bp and -2025 to + 188 bp, -1539 to + 188 bp and -1215 to + 188 bp, -1215 to + 188 bp and -1066 to + 188 bp were significantly different in HEK-293 and SK-N-SH cells. According to the predictions of the JASPAR database, the transcription factors REST, EGR1, and CREB1/HIC2 may bind the DNA sequences of GRIN1 gene from the -337 to -159, -556 to -337, and -704 to -556, respectively. In addition, zinc finger transcription factors may regulate the expression of other differentially expressed fragments.

CONCLUSIONS

Abnormal transcription regulation in the proximal promoter region of GRIN1 (-704 to + 188 bp) may be involved in the course of neuropsychiatric diseases.