Dr Victoria Cowling
2015 British Society of Cell Biology Women in Cell Biology Award
2014 EMBO Young Investigator
2013 MRC Senior Fellowship
2011 Lister Institute Prize Fellowship
2007 MRC Career Development Award
2007 Research Group Leader, Life Sciences, University of Dundee
2003-2007 Post-doctoral research with Prof. Michael Cole, Dartmouth College, NH, USA and Princeton University, NJ, USA. “Regulation and Function of c-Myc”
1997-2002 PhD Biochemistry with Prof. Julian Downward and Prof. Gerard Evan. Imperial Cancer Research Fund, London, UK. Thesis “Regulation of Caspase Activation during Programmed Cell Death”
1994-1997 Emmanuel College, Cambridge University, UK. B.A. (Hons) Natural Sciences. Part II Zoology
Investigating the regulation and function of the mRNA cap
We investigate the regulation and function of the mRNA cap, and use this information to develop new therapies targeted at inhibiting tumour cell and parasite growth and proliferation.
Human cells contain about 25000 protein-encoding genes. We are only beginning to understand how the cell co-ordinately controls expression of these genes. Our focus is on a modification of mRNA called the mRNA cap. The mRNA cap structure protects transcripts from degradation and recruits factors which mediate processing events. We have found that different signals which the cell encounters (developmental, immunological, oncogenic) can alter the rate and extent to which the mRNA cap forms, either across the transcriptome or on specific transcripts. Thus the mRNA cap is an integrator of cellular signalling information, which directs reshaping of the cellular proteome in response to external and internal signals.
The mRNA cap describes a collection of structures which form on the 5’ end of RNA pol II transcripts. Capping enzymes catalyse modification of the first few nucleotides to form the cap. Most of these enzymes are recruited to phosphorylated RNA pol II at the early stages of transcription, thus capping the transcript as it is being synthesised. One cap structure and the enzymes involved in its synthesis are shown below. Our research involves investigating how these capping enzymes function biochemically and how they influence gene expression. We look at how cellular signalling pathways influence the expression or activity of these enzymes to change the genes which are expressed.
Figure 1 mRNA cap and capping enzymes
How does the cell regulate formation of the mRNA cap?
Our interest in the mRNA cap began whilst investigating the Myc family of proto-oncogenes, which are deregulated to some extent in most human cancers. Since therapies do not currently exist to inhibit Myc protein function in tumours, there is significant interest in their mode of action. We discovered that Myc proteins upregulate the proportion of transcripts with a cap structure, correlating with their increased translation. This was a surprising result since cellular regulation of methyl cap synthesis had not been recognised as a mechanism of gene regulation. We have subsequently other mechanisms by which the cell regulates mRNA cap formation
- c-Myc upregulates mRNA capping by increasing RNA pol II phosphorylation which recruits the capping enzymes and by upregulating SAHH which hydrolyses the inhibitory byproduct of cap methylation
- CDK1-cyclin B phosphorylates RNMT increasing its activity during G1 phase. The majority of transcription occurs during G1 phase and thus this mechanism co-ordinates transcription and RNA processing
- Embryonic stem cells express high levels of the mRNA cap methyltransferase RNMT-RAM which is necessary for the expression of pluripotency-associated factors. RAM is the RNMT co-factor. During neural differentiation, ERK1/2-dependent RAM phosphorylation triggers its degradation. This results in reduced mRNA cap methylation, reduced expression of pluripotency-associated genes and upregulation of neural genes.
Currently we are investigating how mRNA cap formation is regulated during embryonic stem cell differentiation, in innate and adaptive immunity and in embryo development.
How are the mRNA capping enzymes regulated?
We are investigating the basic function of the mRNA capping enzymes because this information is critical for understanding how they are regulated. We identify novel capping enzyme subunits and perform structural, biophysical and biochemical studies to characterise the influence of these subunits on mRNA capping.
We identified the RNMT activating subunit RAM. In collaboration with the Dundee Drug Discovery Unit we solved the structure of RNMT-RAM. Working with Andrei Pisliakov in Computational Biology we used Molecular Dynamics to identify regions of RNMT which RAM influences. RAM increases the binding of the methyl donor, s-adenosyl methionine, to RNMT by altering the movement of helices in the active site.
Figure 2 RAM-RNMT
Considering mRNA capping enzymes as therapeutic targets?
We are currently asking whether cancer cells with deregulated gene expression pathways are more sensitive to inhibition of mRNA capping than healthy cells. We have found that particular oncogenes sensitise breast cancer cell lines to inhibition of RNMT. This suggests use of RNMT inhibitors may be most successful therapeutically at treating cancers with these oncogenic mutations.
We are working with the Dundee Drug Discovery Unit to screen for inhibitors of the mRNA capping enzymes. Small molecule inhibitors will be critical to discern the most suitable cancers to treat with mRNA capping inhibitors.
We are working with Mike Ferguson to consider the mRNA capping enzymes as therapeutic targets in T.brucei, the parasite which causes Human African Trypanosomiasis. We are extending this work to other parasites with the Dundee Drug Discovery Unit.
Grasso L, Suska O, Davidson L, Gonatopoulos-Pournatzis T, Williamson R, Wasmus L, Wiedlich S, Peggie M, Stavridis MP, Cowling VH. (2016) mRNA Cap Methylation in Pluripotency and Differentiation. Cell Rep. 2016 Jul 20. pii: S2211-1247(16)30858-0. doi: 10.1016/j.celrep.2016.06.089. [Epub ahead of print] PMID:27452456
Varshney D, Petit AP, Bueren-Calabuig JA, Jansen C, Fletcher DA, Peggie M, Weidlich S, Scullion P, Pisliakov AV, Cowling VH. (2016) Molecular basis of RNA guanine-7 methyltransferase (RNMT) activation by RAM. Nucleic Acids Res. 2016 Jul 15. pii: gkw637. [Epub ahead of print] PMID:27422871
Aregger M, Kaskar A, Fernandez-Sanchez ME, Simone Weidlich S and Cowling VH (2016) CDK1-cyclinB activates RNMT co-ordinating mRNA cap methylation with G1 phase transcription Mol Cell. 2016 Mar 3;61(5):734-46. doi: 10.1016/j.molcel.2016.02.008. View Paper
Preston GC, Sinclair LV, Kaskar A, Hukelmann JL, Navarro MN, Ferrero I, MacDonald HR, Cowling VH and Cantrell DA (2015) Single Cell Tuning of Myc Expression by Antigen Receptor Signal Strength and Interleukin 2 in T Lymphocytes EMBO J. 2015 Jul 1. pii: e20149025 View Paper
Cowling VH, Turner S and Cole MD (2014) Burkitt's lymphoma-associated c-Myc mutations converge on a dramatically altered target gene response and implicate ribosome biogenesis in oncogenesis Oncogene. 2014 Jul 3;33(27):3519-27. doi: 10.1038/onc.2013.338. Epub 2013 Sep 9. View Paper
Gonatopoulos-Pournatzis T and Cowling VH (2014) RAM function is dependent on Kapb2–mediated nuclear entry Biochemical J 2013 2014 Feb 1;457(3):473-84. doi: 10.1042/BJ20131359 View Paper
Aregger M and Cowling VH (2013) Human cap methyltransferase (RNMT) N-terminal non-catalytic domain mediates recruitment to transcription initiation sites Biochem J. 2013 Oct 1;455(1):67-73. doi: 10.1042/BJ20130378 View Paper
Gonatopoulos-Pournatzis T, Dunn S, Bounds R, and Cowling VH (2011) RAM/Fam103a1 is required for mRNA cap methylation Molecular Cell 2011 Nov18;44(4):585-596 View Paper
Cowling VH (2010) Enhanced mRNA cao methylation increases Cyclin D1 expression and promotes cell transformation Oncogene. 2010 Feb 11;29(6):930-6. Epub 2009 Nov 16. View Paper
Fernandez-Sanchez ME, Gonatopoulos-Pournatzis T, Preston G, Lawlor MA, and Cowling VH (2009) S-Adenosyl Homocysteine Hydrolase (SAHH) is required for Myc-induced mRNA cap methylation, protein synthesis and cell proliferation Mol Cell Biol 2009, Dec;29(23):6182-91. Epub 2009 Oct 5. View Paper