WS12.4 Planar cell polarity protein network, which controls ciliogenesis and cilia function, is altered in human cystic fibrosis bronchial epithelial cells through response to endoplasmic reticulum stress

Abstract

Objectives: Mucociliary clearance, abnormal in CF lung, is regulated by several mechanisms including epithelial cilia movement. Planar Cell Polarity (PCP) has been described in mammal lung epithelial cells as a crucial mechanism controlling ciliogenesis and cilia function. Although the majority of studies on cilia in CF showed no structural abnormality and normal cilia beat frequency, cilia disorientation was showed to occur secondary to lung inflammation. We hypothesized that CF HBEs display abnormal PCP network and that could further impair coordinated cilia function. Methods: We quantified expression of several PCP genes in HBEs and observed influence of CFTR genotype on PCP gene expression. By Western-Blot and immunofluorescence, we determined which components of PCP network were abnormal in CF cells. We performed pharmacological studies (F508del-CFTR rescue, ER stress inducing) to determine what causes PCP dysfunction in CF-HBEs. Results: We demonstrated that HBEs expressed several PCP genes. Among them, expression of CELSR3 (Cadherin EGF LAG seven-pass G-type receptor 3) was down-regulated in CF (F508del/F508del) HBEs as compared to non-CF cells. In contrast, Vangl-2 (Van Gogh-like 2), FZD3 (Frizzled 3) and Pk4 (Prickle 4) were unregulated in CF cells. Very low levels of immature (unglycosylated, uncleaved) CELSR3 protein were found in CF cells. ER stress inducers reduced expression of CELSR3 in 16HBE14o- cell lines, suggesting that ER stress affects PCP network in HBE cells. Conclusion: Expression and processing of PCP proteins is abnormal in CF-HBEs and may altered coordinated function of cilia within the bronchial epithelium in Cystic Fibrosis