Submitted on July 2, 2008
Revised on October 20, 2008
Accepted on November 4, 2008
Spiperone, Identified through Compound Screening, Activates Calcium Dependent Chloride Secretion in the Airway
Lihua Liang1, Kelvin D MacDonald1, Erik M Schwiebert2, Pamela L Zeitlin1, and William B Guggino1*
1 Johns Hopkins University School of Medicine
2 DiscoveryBioMed, Inc.
* To whom correspondence should be addressed. E-mail: wguggino{at}jhmi.edu.
Cystic Fibrosis (CF) is caused by mutations in the gene producing the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR functions as a Cl- channel. Its dysfunction limits chloride secretion and enhances sodium absorption, leading to viscous mucus in the airway. Ca2+ activated Cl- channels (CaCCs) are co-expressed with CFTR in the airway surface epithelia. Increases in cytosolic Ca2+ activate the epithelial CaCCs, which provides an alternative Cl- secretary pathway in CF. We developed a screening assay and screened a library for compounds that could enhance cytoplasmic Ca2+, activate CaCC, and increase Cl- secretion. We found that spiperone, a known antipsychotic drug, is a potent intracellular Ca2+ enhancer and demonstrated that it stimulates intracellular Ca2+ not by acting in its well-known role as an antagonist of either 5-HT2 or D2 receptors, but through a protein tyrosine kinase coupled phospholipase C-dependent pathway. Spiperone activates CaCCs, which stimulates Cl- secretion in polarized human non-CF and CF airway epithelial cell monolayers in vitro, and in CFTR knockout mice in vivo. In conclusion: we have identified spiperone as a new therapeutic platform for correcting defective Cl- secretion in CF via a pathway independent of CFTR.
