Phosphoinositide 3-Kinase Alpha-Dependent Regulation of Branching Morphogenesis in Murine Embryonic Lung : Evidence for a Role in Determining Morphogenic Properties of FGF 7

Branching morphogenesis is a critical step in the development of many epithelial organs. The phosphoinositide-3-kinase (PI3K) pathway has been identified as a central component of this process but the precise role has not been fully established. Herein we sought to determine the role of PI3K in murine lung branching using a series of pharmacological inhibitors directed at this pathway. The pan-class I PI3K inhibitor ZSTK474 greatly enhanced the branching potential of whole murine lung explants as measured by an increase in the number of terminal branches compared with controls over 48 hours. This enhancement of branching was also observed following inhibition of the downstream signalling components of PI3K, Akt and mTOR. Isoform selective inhibitors of PI3K identified that the alpha isoform of PI3K is a key driver in branching morphogenesis. To determine if the effect of PI3K inhibition on branching was specific to the lung epithelium or secondary to an effect on the mesenchyme we assessed the impact of PI3K inhibition in cultures of mesenchyme-free lung epithelium. Isolated lung epithelium cultured with FGF7 formed large cyst-like structures, whereas co-culture with FGF7 and ZSTK474 induced the formation of defined branches with an intact lumen. Together these data suggest a novel role for PI3K in the branching program of the murine embryonic lung contradictory to that reported in other branching organs. Our observations also point towards PI3K acting as a morphogenic switch for FGF7 signalling. OPEN ACCESS Citation: Carter E, Miron-Buchacra G, Goldoni S, Danahay H, Westwick J, et al. (2014) Phosphoinositide 3-Kinase Alpha-Dependent Regulation of Branching Morphogenesis in Murine Embryonic Lung: Evidence for a Role in Determining Morphogenic Properties of FGF7. PLoS ONE 9(12): e113555. doi:10.1371/journal.pone. 0113555 Editor: Vladimir V. Kalinichenko, Cincinnati Children’s Hospital Medical Center, United States of America Received: May 15, 2014 Accepted: October 29, 2014 Published: December 2, 2014 Copyright: 2014 Carter et al. This is an openaccess article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Funding: This work was supported my a Medical Research Council Doctoral Training Grant and Novartis Institute of Biomedical Research. Novartis provided reagents for this work and helped in the preparation of the manuscript. Competing Interests: A Medical Research Council Doctoral Training Grant and Novartis Institute of Biomedical Research supported this work. Novartis provided reagents for this work and helped in the preparation of the manuscript. Silvia Goldoni, Henry Danahay and John Westwick are affiliated with Novarits. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials. PLOS ONE | DOI:10.1371/journal.pone. 0113555 December 2, 2014 1 / 22