Award details

Function of the exoribonuclease pacman in cell movement and cell shape change

Reference	BB/G002754/1
Principal Investigator / Supervisor	Professor Sarah Newbury
Co-Investigators / Co-Supervisors	Professor Simon Morley
Institution	University of Sussex
Department	Brighton and Sussex Medical School
Funding type	Research
Value (£)	418,170
Status	Completed
Type	Research Grant
Start date	01/08/2008
End date	31/01/2012
Duration	42 months

Abstract

The conserved 5' - 3' exoribonuclease Pacman/Xrn1 is known to play a critical role in gene regulatory events such as control of mRNA stability, RNA interference, nonsense-mediated decay and regulation via microRNAs. We have shown that this enzyme is often located in cytoplasmic particles termed P-bodies which are thought to be involved in the translational repression and degradation of RNAs. Our recent results show that mutations in the exoribonuclease pacman lead to defects in epithelial sheet sealing processes such as dorsal/thorax closure and wound healing in Drosophila. These epithelial sheet sealing processes are morphologically similar to those seen in eyelid fusion and hind-brain closure in mammals. The overall aim of the project is to understand how the Drosophila exoribonuclease Pacman regulates dorsal closure. We propose that pacman plays a key role in this process by targeting particular RNAs. An attractive hypothesis is that pacman controls dorsal closure by regulating the conserved JNK signaling pathway. This cell signaling pathway is well known to orchestrate cell movement, cell shape change and cell adhesion during the dorsal closure process. To determine the function of pacman in dorsal closure, we will analyse in detail the phenotypic consequences of pacman mutations on dorsal closure and on known regulators of the dorsal closure process. This analysis will give information on the cellular pathways targeted by pacman. We will also identify targets of Pacman during dorsal closure using biochemical techniques and micro-array analysis. The localisation of Pacman protein in relation to P-body components and translational repressors will also be examined in order to assess the involvement of translational repression in this process. These innovative studies will shed light on the role of the pacman ribonuclease in dorsal closure and, more generally, help us to understand the mechanisms whereby particular RNAs are targeted for degradation.

Summary

Wound healing requires the surrounding skin cells to stretch, draw together and seal to cover the hole in the layer of skin cells. This process of wound healing is similar to other cell sheet movements in the development of all embryos. We have shown that an enzyme involved in the destruction of messenger RNAs is necessary for the cell sheet sealing process in the fruit fly Drosophila melanogaster. This enzyme, which is named Pacman, chews up these messenger RNAs from one end to the other. Messenger RNAs are the molecules which instruct the cell to make particular proteins. We have found out that Pacman is likely to be part of a large complex of proteins, a 'Death Star' which can efficiently destroy or imprison messenger RNAs. We suspect that Pacman must destroy RNAs that would potentially stop the cell sheet sealing process. The aim of this project is to find out how Pacman can control this hole closure process. The control mechanism probably involves targeting particular mRNAs for destruction by the 'Death Star' complex and we will test whether this is the case. Although this project will be carried out using the fruit fly Drosophila, it also has relevance for epithelial sheet sealing processes such as wound healing in humans as the cellular processes are surprisingly similar in both organisms. In addition, the Pacman enzyme is extremely similar between flies and humans therefore the insights we gain during this project may help us to improve the treatment for wounds and also help us to understand the cell movement process in embryos. The work described in this proposal is also directed towards the general question of gene regulation at the RNA level. It has recently become recognised that genes can be controlled at the level of the messenger RNA by using RNA itself as a tool to turn down specific genes. In a process termed RNA interference, it is possible to downregulate any particular RNA in the cell. Since Pacman and its homologues have been shown to be involved in RNA interference, this project will also may also provide innovative insights into the improval of this process for therapeutic purposes.

Committee	Closed Committee - Biochemistry & Cell Biology (BCB)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search