Abstract
Asthma is a complex disease, often with evident genetic predisposition; for example, the single-nucleotide polymorphism (SNP) rs7130588 was significantly associated with asthma by genome-wide association study (GWAS). Analysis of 1000 Genomes Project data suggests that there is another SNP, rs6592645, in complete linkage disequilibrium with rs7130588 and should present the same signal in GWAS. However, the causal SNP and the mechanism for the association between rs7130588 and asthma remain to be elucidated. In the presents study, results from dual-luciferase assays indicated that the A/G alleles of rs7130588 failed to present significantly different reporter gene expression. By contrast, A allele of rs6592645 presented a significant increase in relative luciferase activity than G allele, thus suggesting that rs6592645 may be a causal SNP. Using chromosome conformation capture, the enhancer region containing rs6592645 was observed to interact with promoter region of leucine-rich repeat-containing 32 (LRRC32). Gene expression quantification suggested that LRRC32 expression is significantly increased in lung tissue of patients with asthma and is dependent on the genotype of this locus, thus verifying that LRRC32 may be involved in asthma onset and that rs6592645 can regulate LRRC32 expression. Through chromatin immunoprecipitation, transcription factor 3 (TCF3) was identified to bind to rs6592645 surrounding region and the interaction between TCF3 and rs6592645 surrounding region was investigated. Results from the present study may improve our understanding of the mechanism by which the genetic variation in this locus might influence asthma susceptibility.