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Title: Analysis of the biological functions of Kidins220 : from cells to organisms
Author: Cesca, Fabrizia
ISNI:       0000 0004 2674 2336
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2007
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In this work, I have characterised the biological functions of Kidins220 (Kinase D interacting substrate of 220 kDa) in both an in vitro and in vivo context. Kidins220 is a conserved membrane protein mainly expressed in neuronal cells, which has been implicated in the process of neuronal differentiation in response to neurotrophic stimuli. In the first part of this study, I present an analysis of the molecular mechanism regulating the intracellular trafficking of Kidins220 in a rat pheochromocytoma cell line (PC 12), which upon treatment with nerve growth factor (NGF) differentiates into neuronal-like cells resembling sympathetic neurons. Kidins220 transport to neurite tips is driven by the microtubule-dependent motor complex kinesin-1. Perturbation of Kidins220 trafficking in this cellular system reduces the activation of the signalling cascades initiated by NGF and impairs neuronal differentiation. I was interested in understanding the mechanisms that might modulate the association of Kidins220 to kinesin-1. Kidins220 recruits kinesin-1 via a novel binding motif, which does not share any similarities with the known kinesin-1- interacting signatures. I found that Abelson tyrosine kinase (Abl) phosphorylates Kidins220 at the level of this kinesin interacting motif, thus inhibiting the binding to kinesin light chain. These preliminary results suggest that phosphorylation might act as a molecular switch, to mediate the release of Kidins220 from the kinesin-1 motor complex. In the second part of this work, I analysed the effects of Kidins220 depletion in living organisms. I tackled this problem by targeting Kidins220 by RNA interference in Drosophila melanogaster. In an independent approach, I have generated a construct, based on the Cre/LoxP recombination system, for the conditional knockout of the Kidins220 gene in mice. Kidins220 null animals die at late stages of embryonic development, and display severe cardiovascular and neurological defects. Their phenotype is described in detail using a variety of immunohistochemical and cell biological approaches. This work therefore presents new evidence supporting the notion that Kidins220 plays an important role in regulating not only neuronal function and differentiation, but also other key developmental processes such as cardiac development.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available