This study identified a transcription factor that might bind to the 5′ regulatory region of the HTR1A and explored the potential effect on 5-HT1A receptor expression. Based on JASPAR predictions, the binding of the transcription factor was demonstrated using the electrophoretic mobility shift assay (EMSA). Vectors over-expressing the transcription factor were co-transfected into HEK-293 and SK-N-SH cells with the recombinant pGL3 vector, and relative fluorescence intensity was measured to determine regulatory activity. Additionally, the qRT-PCR and Western blot were also used to identify whether the transcription factor modulated the endogenous expression of 5-HT1A receptor. The results suggest that the transcription factor CCAA/T enhancer binding protein beta (CEBPB) likely binds to the −1219 to −1209 bp (ATG+1) region of the HTR1A. Two sequences located in the −722 to −372 bp and −119 to +99 bp were also identified. Although the effect of CEBPB on endogenous 5-HT1A receptor expression was not significant, it exhibited the strong inhibition on the relative fluorescence intensity and the mRNA level of HTR1A. CEBPB inhibited the human HTR1A expression by binding to the sequence −1219–−1209 bp. This is useful and informative for ascertaining the regulation of 5-HT1A receptor and mental diseases.

The serotonin neurotransmitter (5-HT) and its receptors have important roles in neuropsychiatric disorders such as schizophrenia. The aim of this study was to investigate the functional sequences of the 5′ regulation region of the human HTR1A gene to explore the effects on the expression of the 5-HT1A receptor. Fourteen recombinant pGL3-basic vectors containing deletion fragments of the HTR1A gene regulatory region were transfected with HEK-293 and SK-N-SH cells. The relative chemiluminescence intensities of different length fragments were analyzed. The JASPAR software was used for the prediction of transcription factors. In the HEK-293 cells, the relative chemiluminescence intensity of the − 1649 bp to − 1550 bp (ATG + 1) fragment was significantly different. Two inhibitory activity regions were found in the − 1409 bp to − 1381 bp and − 1196 bp to − 1124 bp fragments, which might be bound to the GATA or SOX10 transcription factors as predicted by the JASPAR software. In addition, the fragments located from − 1124 bp to − 1064 bp and from − 908 bp to − 722 bp up-regulated protein expression. Only the sequence from − 1550 bp to − 1409 bp demonstrated a difference in luciferase expression in the both cell lines. According to the results of the 5’-UTR truncated vectors, there was a repression region at the distal end of the 5’-UTR, an enhancer region might be present at the proximal end of the transcription start site. Although the functional sequences of the HTR1A gene regulatory region were confirmed, the regulatory factors and functional components require further investigation.

Background: The level of the regulator of G-protein signaling 4-1 (RGS4-1) isoform, the longest RGS4 isoform, is significantly reduced in the dorsolateral prefrontal cortex (DLPFC) of people with schizophrenia. However, the mechanism behind this has not been clarified. The 3′untranslated regions (3′UTRs) are known to regulate the levels of their mRNA splice variants. Methods: We constructed recombinant pmir-GLO vectors with a truncated 3′ regulatory region of the RGS4 gene (3R1, 3R2, 3R3, 3R4, 3R5, and 3R6). The dual-luciferase reporter assay was conducted to find functional regions in HEK-293, SK-N-SH, and U87cells and then predicted miRNA binding to these regions. We performed a dual-luciferase reporter assay and a Western blot analysis after transiently transfecting the predicted miRNAs. Results: The dual-luciferase reporter assay found that regions +401–+789, +789–+1152, and +1562–+1990 (with the last base of the termination codon being +1) might be functional regions. Hsa-miR-874-3p, associated with many psychiatric disorders, might target the +789–+1152 region in the 3′UTR of the RGS4 gene. In the dual-luciferase reporter assay, the hsa-miR-874-3p mimic, co-transfected with 3R1, down-regulated the relative fluorescence intensities. However, this was reversed when the hsa-miR-874-3p mimic was co-transfected with m3R1 (deletion of +853–+859). The hsa-miR-874-3p mimic significantly decreased the endogenous expression of the RGS4-1 isoform in HEK-293 cells. Conclusions: Hsa-miR-874-3p inhibits the expression of the RGS4-1 isoform by targeting +853–+859.