Transcription Factor CEBPB Inhibits the Expression of the Human HTR1A by Binding to 5′ Regulatory Region In Vitro

This study identified a transcription factor that might bind to the 5&rsquo
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.