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Characterisation of early patterning events during Drosophila eye morphogenesis

Robertson, F.; (2011) Characterisation of early patterning events during Drosophila eye morphogenesis. Doctoral thesis, UCL (University College London).

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Abstract

Epithelial tissue morphogenesis relies on tightly regulated cell shape changes and local cell-cell contact rearrangements. However, our knowledge on how these cells’ behaviours are controlled and implemented during organogenesis remains incomplete. To address this issue, I have made use of the genetically amenable developing Drosophila eye. Patterning of the Drosophila eye is initiated by the morphogenetic furrow (MF), a developmental compartment characterized by a wave of apically constricted cells that travels from the posterior pole of the disc. In the wake of the MF emerges a regular array of aligned photoreceptor-precursor cells that will further assemble into mature ommatidia, the building blocks of the fly’s compound eye. My thesis work is concerned with characterizing the cellular and molecular mechanisms directing early ommatidia patterning. My work demonstrates that the alignment of the ommatidial precursor cells is directed by the basic helix-loop-helix transcription factor Atonal (Ato). In the wake of the MF, interfaces between ato-expressing and non-expressing cells promote the planar polarization of the acto-myosin (MyoII) cortex along the anterior-posterior axis. Consequently, MyoII is required to establish the complementary polarisation of the zonula adherens factors ECadherin (E-cad) and Bazooka (Baz) and to direct multicellular alignment. Further, my work indicates that in parallel, transcription downstream of Epidermal growth factor receptor (EGFR) signalling is required to sustain MyoII planar polarization as the clusters of aligned cells evolve toward more mature ommatidia. Importantly, both Ato and EGFR modulate E-cad levels in the wake of the MF and we propose that differences in ECad expression create interfacial tensions at the boundary between the MF and more posterior cells. In my model, this provides the directionality for polarizing MyoII. I propose that this cell response directs the alignment of group of cells such that the subsequent orderly and stereotyped EGFR-dependent recruitment of photoreceptors can proceed.

Type:Thesis (Doctoral)
Title:Characterisation of early patterning events during Drosophila eye morphogenesis
Language:English
Additional information:Permission for digitisation not received
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Life Sciences > MRC/UCL Lab for Molecular Cell Biology

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