The Role of DUOX Isozymes in the Respiratory Tract Epithelium

Increasingly, reactive oxygen species such as superoxide and hydrogen peroxide are recognized to be intentionally generated intracellularly to serve important cellular functions. A key protein family responsible for the regulated generation of reactive oxygen species in multiple cell types is the NOX/DUOX enzyme family. Two family members, DUOX1 and DUOX2, appear to be highly expressed in tissues of endodermal origin including the thyroid, respiratory tract, and gastrointestinal tract. In this chapter, we will focus our review on DUOX proteins in the respiratory tract. We will discuss a brief history of the discovery of the DUOX isoforms, the estimated hydrogen peroxide-generating capacity of DUOX in respiratory tract epithelium, putative functions of the DUOX enzymes, and some regulatory factors responsible for DUOX gene expression and oxidase activity.