S-nitrosation of protein phosphatase 1 mediates alcohol-induced ciliary dysfunction

Michael E Price,Jane M Devasure,Adam J Case,Todd A Wyatt,Joseph H Sisson,Jacqueline A Pavlik,Matthew C Zimmerman

doi:10.1038/s41598-018-27924-x

Abstract

Alcohol use disorder (AUD) is a strong risk factor for development and mortality of pneumonia. Mucociliary clearance, a key innate defense against pneumonia, is perturbed by alcohol use. Specifically, ciliated airway cells lose the ability to increase ciliary beat frequency (CBF) to β-agonist stimulation after prolonged alcohol exposure. We previously found that alcohol activates protein phosphatase 1 (PP1) through a redox mechanism to cause ciliary dysfunction. Therefore, we hypothesized that PP1 activity is enhanced by alcohol exposure through an S-nitrosothiol-dependent mechanism resulting in desensitization of CBF stimulation. Bronchoalveolar S-nitrosothiol (SNO) content and tracheal PP1 activity was increased in wild-type (WT) mice drinking alcohol for 6-weeks compared to control mice. In contrast, alcohol drinking did not increase SNO content or PP1 activity in nitric oxide synthase 3-deficient mice. S-nitrosoglutathione induced PP1-dependent CBF desensitization in mouse tracheal rings, cultured cells and isolated cilia. In vitro expression of mutant PP1 (cysteine 155 to alanine) in primary human airway epithelial cells prevented CBF desensitization after prolonged alcohol exposure compared to cells expressing WT PP1. Thus, redox modulation in the airways by alcohol is an important ciliary regulatory mechanism. Pharmacologic strategies to reduce S-nitrosation may enhance mucociliary clearance and reduce pneumonia prevalence, mortality and morbidity with AUD.

Highlights

Alcohol abuse is associated with 80,000 deaths and a ~$240 billion economic loss per year in the United States[1,2]
We recently identified that phosphatase 1 (PP1) cysteine 155 (PP1C155) is oxidized in bovine airway axonemes after alcohol exposure, which correlated with the desensitization of isolated axoneme ciliary beat frequency (CBF) to cyclic adenosine monophosphate (cAMP)
We hypothesized that alcohol exposure drives an increase in PP1 activity by S-nitrosation of PP1C155 resulting in desensitization of CBF

Summary

Introduction

Alcohol abuse is associated with 80,000 deaths and a ~$240 billion economic loss per year in the United States[1,2]. Key to mucociliary clearance is the coordinated movement, or beating, of motile cilia functioning as an escalator to propel mucus-trapped pathogens out of the airway. These cilia maintain a baseline resting frequency that, upon stimulation by mechanical or chemical stimuli, rapidly increases to improve clearance[6]. Initial stimulation of CBF by alcohol requires activation of sequential nitric oxide (·NO) and cAMP-dependent pathways that are intrinsic to cilia organelles, and occurs independent of the cell[10]. Our results suggest that direct S-nitrosation of PP1 increases enzymatic activity and that oxidation of cysteine 155 is a key component in the alcohol-driven desensitization of CBF stimulation

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