Protein trafficking and gene regulation

Peter O'Hare PhD - Group Leader

Fernando Abaitua, PhD
Marianne Bolstad, PhD
Suzanne Carreira, PhD
Marta Llarena, PhD
Kathy May, BSc


 

We aim to understand the processes and factors involved in regulating aspects of subcellular organisation and protein trafficking and how these processes ultimately modulate gene expression. For some of these projects we gain particular insight from analysis of virus-host interactions. We currently have four main project groups.

Regulated intramembrane proteolysis:

A small group of BZip transcription factors contain a transmembrane domain. Unusually, their main mode of regulation is via site-specific proteolytic cleavage within the transmembrane domain in response to distinct environmental or stress stimuli, releasing the BZip domain for trafficking to the nucleus. We aim to identify the factors involved in the localisation of this specialised set of proteins, the signals regulating cleavage, and their downstream target genes. We are also investigating whether alteration in their activity contributes to tissue specific disease.

VP16 and HCF trafficking:

Analysis of the basic biochemistry of VP16 transcription and its interaction with two host proteins, Oct-1 and HCF, has contributed significantly to our understanding of general principles in eukaryotic gene control. However the precise role of HCF, and its normal cellular function(s), remain significant gaps in our knowledge. Current work is directed at understanding the HCF proteins in the cell cycle and their distinct compartmentalisation properties

SUMO modification:

SUMO is a post-translational modification which controls compartmentalisation and stability of target proteins. Modification may take place in defined subnuclear structures which are organised by the protein, PML (involved in the development of Promyelocytic Leukaemia). The viral factor IE110k is a RING finger protein which acts as a broad spectrum activator of gene expression and appears to function by disrupting the normal modification and stability of SUMO modified cellular proteins. We aim to elucidate the links between SUMO modification and ubiquitination, the PML protein and sub-nuclear compartmentalisation. Additional projects within this programme are directed towards understanding the role of IE110k and of PML in the cytokine signalling pathway.

Nuclear envelope reorganisation:

This work focuses on changes to the lamina and nuclear membrane proteins, as HSV matures through the inner nuclear envelope. In particular current studies involve analysis of the reorganisation of e.g. lamin B receptor-GFP fusion proteins, or the lamins themselves, at various stages after infection in living cells, and biochemical aspects of lamin composition. The work aims to provide an understanding of how HSV exits the nucleus, and to broaden our understanding of key interactions in nuclearenvelope/lamina organisation.

Selected references:

Abaitua, F. and O'Hare, P. (2008)
Identification of a highly conserved, functional nuclear localization signal within the N-terminal region of Herpes Simplex Virus Type 1 VP1-2 tegument protein.  J. Virol., 82: 5234-5244.

Morris, J.B., Hofemeister, H. and O’Hare, P. (2007)
Herpes simplex virus infection induces phosphorylation and delocalization of emerin, a key inner nuclear membrane protein.
J. Virol., 81: 4429-4437.

Barreca, C. and O’Hare, P. (2006)
Characterisation of a potent refractory state and persistence of herpes simplex virus 1 in cell culture.
J. Virol., 80: 9171-9180.

Howat, T.J., Barreca, C., O’Hare, P., Gog, J.R. and Grenfell, B.T. (2006)
Modelling dynamics of the type I interferon response to in vitro viral infection.
J.R. Soc. Interface, http://dx.doi.org/10.1098/rsif.2006.0136.

Stirling, J. and O’Hare, P. (2006)
CREB4, a transmembrane bZip transcription factor and potential new substrate for regulation and cleavage by S1P.
Mol. Biol. Cell, 17: 413-426.

Bailey, D. and O’Hare, P. (2005)
Comparison of the SUMO-1 and ubiquitin conjugation pathways during the inhibition of proteasome activity with evidence of SUMO-1 recycling.
Biochem. J., 392: 271-281.

Mouzakitis, G., McLauchlan, J., Barecca, C., Kueltzo, L. and O’Hare, P. (2005)
Characterisation of VP22 in herpes simplex virus infected cells.
J.Virol., 79: 12185-12198.

Juang, B.-T., Izeta, A., O’Hare, P. and Luisi, B.F. (2005) Purification and Characterization of the Caenorhabditis elegans HCF protein and domains of human HCF.
Biochemistry, 44: 10396-10405.

Hofemeister, H. and O’Hare, P. (2005)
Analysis of the localization and topology of nurim, a polytopic protein tightly associated with the inner nuclear membrane.
J. Biol. Chem., 280: 2512-2521.

Bailey, D. and O'Hare, P. (2004)
Characterisation of the localisation and proteolytic activity of the SUMO-specific protease, SENP1.
J. Biol. Chem., 279: 692-703.

Ragio, C., Rapin, N., Stirling, J. Gobeil, P., Smith-Windsor, E., O'Hare, P. and Misra, V. (2002)
Luman, the cellular counterpart of VP16 is processed by regulated intramembrane proteolysis.
Mol. Cell. Biol., 15: 5639-5649.

Scott, E. and O'Hare, P. (2001)
Fate of the inner nuclear membrane protein lamin B receptor and nuclear lamins in HSV-1 infection.
J. Virol., 75: 8818-8830.