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Title: The involvement of phosphoinositide 3-kinase in murine lung branching morphogenesis and insights into protein mediated drug delivery
Author: Carter, Edward
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2014
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Epithelial branching morphogenesis is a critical step in the development of many epithelial organs including the lungs and the salivary glands. Many of the signalling pathways that orchestrate this process show a resurgence in the diseased state. We sought to determine the role of a common disease pathway, the phosphoinositide 3-kinase (PI3K) pathway, in the branching program of the lung. We utilised ex-vivo cultures of embryonic murine lungs that best recapitulates the developmental process. Inhibition of PI3Kα, or its downstream signalling components Akt and mammalian target of rapamycin, was able to greatly enhance the branching potential of embryonic lungs, implying a negative role for PI3K in the lung branching morphogenesis. Moreover inhibition of PI3K was sufficient to alter the morphogenic properties of fibroblast growth factor 7 on isolated murine lung epithelium from a cystic to a branching response. We also investigated protein mediated drug delivery tools to provide a means of enhancing the delivery of PI3K based therapeutics. Cell-penetrating peptides (CPPs) are small proteins that are able to transport a drug cargo across the membrane of a cell. However, given that many CPPs are derived from viral proteins and venoms we sought to determine if common CPPs could induce an immune response. CPPs we capable of delivering a protein cargo into the interior of epithelial cells without inducing an immune response as measured by a lack of NFκB activation and no observable increase in interleukin-6 or -8 secretion. We finally explored the potential of repurposing bacterial toxins for therapeutic applications. The toxins Pseudomonas aeruginosa exotoxin A (PEx) and Cholix (Chx) are natively capable of entering cells and subsequently being transported to either the cytoplasm of non-polarised cells, or undergoing transcytosis across polarised cells. We were able to identify that the C16:1 ceramide chain variant of the ganglioside GM1 is capable of enhancing the intracellular transport of PEx to the Golgi network. Moreover, we demonstrated that PEx is able to transport an siRNA cargo across polarised monolayers of Caco-2 cells and deliver said cargo into cells present in the basolateral compartment.
Supervisor: Ward, Stephen ; Tosh, David ; Watson, Malcolm Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available