Integrins are cell surface adhesion proteins that act both as receptors for the extracellular matrix and as signalling molecules. They are heterodimers of α and β subunits, both of which contribute to ligand binding. The <I>inflated </I>(<I>if</I>) gene encodes the α<SUB>PS2</SUB> subunit of the <I>Drosophila</I> PS2 integrin. It is required for midgut morphogenesis and somatic muscle attachment in the embryo and for adhesion between the two epidermal layers of the wing blade in the adult. It has been proposed that it functions simply to mediate adhesion between distinct cell layers. The aim of this thesis has been to investigate (1) whether PS2 integrin has additional roles during <I>Drosophila</I> development, (2) whether it mediates cell signalling and (3) elucidate which regions of the α<SUB>PS2</SUB> protein are important for PS2 integrin function. In order to address these questions a comprehensive genetic analysis of the <I>inflated</I> gene was performed. Several novel classes of <I>inflated</I> mutation were characterised based upon both their interallelic complementation behaviour and phenotypes. This analysis identified distinct embryonic roles for PS2 integrin in the attachment of the somatic muscles, the formation of muscle ultrastructure, and in the morphogenesis of the midgut. New roles for PS2 were also identified in the adult, in the morphogenesis of the halteres and legs. Molecular analysis of the defects underlying some of the novel <I>inflated</I> mutations suggests a model for PS2 integrin function in which the integrin can exist in two mutually exclusive activation states that are required for different PS2 integrin functions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:596726 |
| Date | January 1997 |
| Creators | Bloor, James W. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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