Bcl-2 Suppresses Sarcoplasmic/Endoplasmic Reticulum Ca²⁺-ATPase Expression in Cystic Fibrosis Airways

Abstract

Rationale: Modulation of the activity of sarcoendoplasmic reticulum calcium ATPase (SERCA) can profoundly affect Ca 21 homeostasis. Although altered calcium homeostasis is a characteristic of cystic fibrosis (CF), the role of SERCA is unknown. Objectives: This study provides a comprehensive investigation of expression and activity of SERCA in CF airway epithelium. A detailed study of the mechanisms underlying SERCA changes and its consequences was also undertaken. Methods: Lung tissue samples (bronchus and bronchiole) from subjects with and without CF were evaluated by immunohistochemistry. Protein and mRNA expression in primary non-CF and CF cells was determined by Western and Northern blots. Measurements and Main Results: SERCA2 expression was decreased in bronchial and bronchiolar epithelia of subjects with CF. SERCA2 expression in lysates of polarized tracheobronchial epithelial cells from subjects with CF was decreased by 67% as compared with those from subjects without CF. Several non-CF and CF airway epithelial cell lines were also probed. SERCA2 expression and activity were consistently decreased in CF cell lines. Adenoviral expression of mutant F508 cystic fibrosis transmembrane regulator gene (CFTR), inhibition of CFTR function pharmacologically (CFTR inh 172), or stable expression of antisense oligonucleotides to inhibit CFTR expression caused decreased SERCA2 expression. In CF cells, SERCA2 interacted with Bcl-2, leading to its displacement from caveolae-related domains of endoplasmic reticulum membranes, as demonstrated in sucrose density gradient centrifugation and immunoprecipitation studies. Knockdown of SERCA2 using siRNA enhanced epithelial cell death due to ozone, hydrogen peroxide, and TNF-a. Conclusions: Reduced SERCA2 expression may alter calcium signaling and apoptosis in CF. These findings decrease the likelihood of therapeutic benefit of SERCA inhibition in CF.

Expression and Prognostic Roles of TRPV5 and TRPV6 in Non-Small Cell Lung Cancer after Curative Resection

“…The increase in [Ca 2 ] Ion channel DOI:http://dx.doi.org/10.7314/APJCP.2014.15.6.2559 Expression andPrognostic Role of TRPV5 andTRPV6 in NSCLC permeability and mitochondrial [Ca 2 ] could activate mitochondrial membrane permeabilization and lead to apoptosis and necrosis. In contrast, the decrease in Ca 2 contents of the endoplasmic reticulum lumen is associated with resistance to apoptosis (Ahmad et al, 2009). In this study, changes in TRPV and its association with cancer differentiation were noticed, as observed in other reports (Dhennin-Duthille et al, 2011).…”

Sarcoendoplasmic Reticulum Ca2+ ATPase. A Critical Target in Chlorine Inhalation–Induced Cardiotoxicity

“…Our earlier studies with environmental oxidant gas exposures revealed enhanced airway epithelial cell death and subsequent loss of SERCA activity (17,25). We also demonstrated that diseased cystic fibrosis airway epithelium with already decreased SERCA function was highly susceptible to oxidant gas exposures (17,25). SERCA dysfunction in the heart causes severe cardiac dysfunction and death in animal models (26).…”

Tissue Factor Signals Airway Epithelial Basal Cell Survival via Coagulation and Protease-Activated Receptor Isoforms 1 and 2

“…Cell harvest and culture were performed using established procedures (20). Briefly, epithelial cells were removed from lower trachea and bronchi by protease XIV digestion and plated in bronchial epithelial growth medium on collagen-coated dishes.…”

“…HAECs were isolated from tracheas and bronchi of patients dying from nonlung disease (20). Passage 1 HAECs were harvested at 80% confluence.…”