Investigating the role of RGC-32 in cell cycle disruption by EBV EBNA 3C

Schlick, Sandra (2010) Investigating the role of RGC-32 in cell cycle disruption by EBV EBNA 3C. Doctoral thesis (DPhil), University of Sussex.

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Abstract

Epstein-Barr virus (EBV) immortalises resting B-lymphocyctes and is associated with a
diverse range of cancers and establishes a persistent, latent infection in >90% of the
world-wide population. Epstein-Barr virus nuclear antigen (EBNA) 3C is one of only
six EBV latent proteins that are crucial for B-cell transformation. EBNA3C is known to
disrupt cell-cycle control and to progress phase transition at G1/S and G2/M under
conditions where cells should growth arrest, but the mechanism by which EBNA3C
does this has not been fully determined. The cell-cycle regulator response gene to
complement (RGC) 32 was found to be upregulated in EBNA3C-expressing cells in
microarray experiments carried out previously. RGC-32 is involved in cell-cycle
activation and also plays a role in G1/S and G2/M transition. I have shown that both
EBNA3C-expressing cell-lines with upregulated RGC-32 and cell-lines overexpressing
RGC-32 alone displayed disrupted G2/M checkpoint control indicating that EBNA3C
may overcome cell-cycle control by upregulation of RGC-32. I also confirmed that
RGC-32 increases the in vitro kinase activity of CDK1, the key mitotic kinase essential
for G2/M transition. Surprisingly, my data showed that EBNA3C only activated RGC-
32 transcription in reporter assays at a very low-level, but stabilised the RGC-32
mRNA. Further studies investigating the differential expression of RGC-32 in EBVpositive
and negative cells demonstrated that RGC-32 is upregulated in LCLs and
tumour (Burkitt’s lymphoma) cell-lines expressing the full panel of latent genes, but
intriguingly highly expressed in Burkitt’s lymphoma cell-lines expressing only EBNA
1. I found that this expression pattern correlated with expression of the RUNX1
transcription factor. Reporter assays revealed that RUNX1 was able to activate the
RGC-32 promoter. Together, this data indicates a new mechanism by which EBNA 3C
can disrupt the G2/M checkpoint and highlights a link between RUNX1 and RGC-32
expression in B-cells.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: Q Science > QH Natural history > QH0301 Biology
Q Science > QR Microbiology
Depositing User: Library Cataloguing
Date Deposited: 22 Jan 2013 07:03
Last Modified: 12 Oct 2015 11:07
URI: http://sro.sussex.ac.uk/id/eprint/43520

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