This renewal application seeks funding to define a transcriptional network that determines AEC differentiation, goblet cell metaplasia/hyperplasia, and inflammation related to the pathogenesis of asthma, other chronic pulmonary disorders, and acute viral infection by rhinovirus. The application is based on novel data demonstrating the critical roles of the proposed transcriptional network that is centered on an Ets family member, SPDEF (SAM pointed domain ets-like factor) that regulates goblet cell differentiation and inflammatory processes in the lung. Our preliminary data demonstrate that differentiation of AECs in conducting airways is mediated by a cell intrinsic transcriptional program in which SPDEF and FOXA family members and TTF-1 (thyroid transcription factor-1, aka Nkx2.1) play fundamental roles. Preliminary data support the concept that Spdef drives mucus cell metaplasia, eosinophilic chemokine, and TH2 cytokine expression from AECs in response to allergens and rhinoviral infection. The application will utilize transgenic mouse models in which Spdef is deleted or expressed; bioinformatics, in vitro cultures of human bronchial epithelial cell (HBECs), and biochemistry to determine mechanisms by which SPDEF controls mucus metaplasia and innate immunity. Aim 1 will identify the mechanisms by which the transcription factor SPDEF is regulated at transcriptional and post-transcriptional levels during mucus metaplasia induced by rhinovirus and aeroallergen exposure. Mechanisms controlling its regulation and function will be identified. Aim 2 will test the hypothesis that SPDEF regulates transcription of genes critical for mucus cell differentiation, innate immunity, and inflammation i the respiratory epithelium, identifying transcriptional targets in AECs. Aim 3 will identify physiological and inflammatory consequences of SPDEF in mouse models in vivo, identifying the effects of the network on pulmonary physiology, inflammatory responses, and tissue remodeling during viral infection and TH2 stimulation. The present application represents my laboratory's increasing interest in the transcriptional control of conducting airway epithelial cel differentiation in health and disease. These studies will provide insights into the pathogenesis of mucus cell metaplasia and hyperproduction associated with asthma, COPD, and acute infections that commonly complicate these disorders, providing the basis for the development of new strategies to diagnose and treat chronic respiratory diseases that are common causes of morbidity and mortality world- wide.