Correlation study on β2-adrenergic receptor gene polymorphisms and asthma susceptibility: evidence based on 57 case-control studies

Transcription Factor E2F1 Regulates the Expression of ADRB2

Adrenergic beta-2-receptor (ADRB2) is highly expressed in various tissue cells, affecting the susceptibility, development, and drug efficacy of diseases such as bronchial asthma and malignant tumor. However, the transcriptional regulatory mechanism of the human ADRB2 gene remains unclear. This study aimed to clarify whether E2F transcription factor 1 (E2F1) was involved in the transcriptional regulation of the human ADRB2 gene. First, the 5' flanking region of the human ADRB2 gene was cloned, and its activity was detected using A549 and BEAS-2B cells. Second, it was found that the overexpression of E2F1 could increase promoter activity by a dual-luciferase reporter gene assay. In contrast, treatment of knockdown of E2F1 significantly resulted in a decrease in its promoter activity. Moreover, mutation of the binding site of E2F1 greatly reduced the potential of human ADRB2 promoter transcriptional activity to be regulated by E2F1 overexpression and knockdown. Additionally, by real-time quantitative PCR and Western blot analysis, we demonstrated that overexpression of E2F1 elevated the ADRB2 mRNA expression and protein levels while si-E2F1 reduced its expression. Finally, the consequence of the chromatin immunoprecipitation assay showed that E2F1 was able to bind to the promoter region of ADRB2 in vivo. These results confirmed that E2F1 upregulated the expression of the human ADRB2 gene.

Association between ADRB2 regulatory region polymorphisms and susceptibility to childhood asthma

OBJECTIVES

To study the association of β2-drenergic receptor (ADRB2) regulatory region single nucleotides polymorphism (SNP)/haplotypes at rs11168070, rs17108803, rs2053044, rs12654778, rs11959427, and rs2895795 loci with childhood asthma.

METHODS

A total of 143 children with asthma who attended the hospital from October 2016 to October 2020 were enrolled as the asthma group, among whom 61 children had mild symptoms (mild group) and 82 children had moderate-to-severe symptoms (moderate-to-severe group). A total of 137 healthy children were enrolled as the control group. Peripheral venous blood samples were collected from the two groups. The SNaPshot SNP technique was used to analyze the SNP and haplotypes of the ADRB2 regulatory region at rs11168070, rs17108803, rs2053044, rs12654778, rs11959427, and rs2895795 loci in all children. The asthma group and the control group were compared in terms of the association of ADRB2 regulatory region SNP and haplotypes at the above six loci with susceptibility to asthma and severity of asthma.

RESULTS

Polymorphisms were observed in the ADRB2 regulation region at the above six loci in both the asthma group and the control group, with significant differences between the two groups in the distribution of genotype and allele frequencies at rs2895795 (-1429T /A), rs2053044(-1023G/A), and rs12654778 (-654G/A) loci (P<0.05). Linkage disequilibrium of SNP was observed at the six loci of the ADRB2 regulatory region.The haplotypes of TATGCT, TATGGC, and AGTGCT were associated with susceptibility to childhood asthma, among which TATGCT and TATGGC were risk factors for childhood asthma (OR=1.792 and 1.946 respectively, P<0.05), while AGTGCT was a protective factor (OR=0.523, P<0.05).

CONCLUSIONS

SNP/haplotype of the ADRB2 regulatory region is associated with the susceptibility to childhood asthma. The haplotypes of TATGCT and TATGGC formed by such SNP/haplotype are risk factors for childhood asthma, while AGTGCT is a protective factor.