Mechanisms elevating ORMDL3 expression in recurrent wheeze patients: role of Ets-1, p300 and CREB.

The first genetic factor identified for childhood asthma by genome-wide association study (GWAS) is the locus on chromosome 17q21, harboring the Orosomucoid 1-like 3 (ORMDL3) gene. ORMDL3 is implicated in facilitation of endoplasmic reticulum-mediated inflammatory responses, believed to underlie its association with asthma. In the present study, we demonstrated that mRNA expression of ORMDL3 is significantly increased in the peripheral blood of recurrent wheeze patients compared with normal control subjects by real-time RT-PCR. To elucidate the molecular mechanisms involved in human ORMDL3 regulation, we cloned and characterized the promoter region of ORMDL3. Applying 5'-rapid amplification of cDNA end analysis (RACE), we revealed that ORMDL3 gene used multiple transcriptional start sites (TSSs). Using a series of 5' deletion promoter plasmids in luciferase reporter assays, we identified that the proximal minimal promoter of ORMDL3 was located within the region -84/+58 relative to the TSS. Mutational analysis, RNA interference experiments and sequential chromatin immunoprecipitation (ChIP) assay demonstrated that transcriptional activity of the ORMDL3 gene was cooperatively regulated by multiple transcription factors, including Ets-1, p300 and CREB. The expression levels of Ets-1, p300 and CREB were increased in the peripheral blood of recurrent wheeze patients compared with normal control subjects and showed a strong linear correlation with the expression of ORMDL3. Our findings indicate that Ets-1, p300 and CREB binding to the promoter region drive the ORMDL3 transcription.