Fig. 7.

Model for negative regulation of CFTR expression during hypoxia by HIF-1 and miR-200b. During hypoxia, HIF-1 activity is induced and HIF-1 binds to the hypoxia response element (HRE) sequence located in CFTR 5′UTR and has been reported to decrease CFTR expression (Zheng et al. [18]). Our studies show that HIF-1 induces miR-200b expression and binds to the target sequence (TS miR-200b) located at the 3′UTR of CFTR mRNA, which further decreases CFTR mRNA and protein expression