Dr Jean-Christophe Bourdon

• University Senior Research Fellow, Principal Investigator, co-director of the Laboratoire Europeen de recherche Associé (Associated European Laboratory) associated with Inserm laboratory U589 directed by Anne-Catherine Prats (Toulouse University, France).
• 1997 Ph.D in Cellular and Molecular Biology entitled “Identification and characterisation of genes induced by p53”Paris XI University, Paris, France-under the supervision of Dr. Evelyne MAY and Prof Brigitte Debuire, Laboratoire de Cancerogenèse Moléculaire- CNRS/Centre d’Etude Nucléaire de Fontenay aux Roses- France
• 1993 D.E.A in Cellular Biology and Biochemistry, Paris XI University, Paris, France.
• 1991 Maitrise in Biochemistry and Molecular Biology, Paris XI University, Paris, France.
• 1990 Licence in Biochemistry and Molecular Biology, Paris XI University, Paris, France.

p53 isoforms

The p53 protein is the product of a critical tumour suppressor gene. Its inactivation by mutation or by protein interactions is thought to be ubiquitous in cancers. Indeed mutations in the p53 gene are found in 50% of human cancers and germline mutations pose an enhanced risk of developing cancer. p53 is a latent and labile transcription factor that is activated in response to cell damage such as DNA damage (UV light, ionising radiation, cigarette smoke), hypoxia, viral infection, oncogene activation, pH variation, temperature variations, etc…. . Activated p53 induces transcription of a host of target genes involved in growth arrest, apoptosis and DNA repair thereby preventing damaged cells for becoming cancerous. In fact defects in the p53 pathway, whether through inactivation of the p53 gene itself or of components of the pathway, are thought to be involved in the majority of cancers. Thus the study of the p53 gene and its protein products and of the p53 pathway has become the focus of intensive basic and clinical research.
The p53-related genes p63 and p73 are alternatively spliced and contain an internal promoter in intron 3 leading to expression of p63 or p73 proteins deleted of the transactivation domain. For 25 years, it was thought that the p53 gene structure was relatively simple, with one promoter and three mRNAs arising from alternative splicing giving rise to three p53 products observed p53, p53i9 (alternative splicing of intron-9) and delta40p53 (alternative splicing of intron-2). delta40p53 can also be produced through alternative initiation of translation at codon 40. Using Generacer PCR methods, we identified in normal tissue, 2 novel splice variants of human p53 encoding for truncated p53 proteins deleted of the oligomerisation domain (p53beta and p53gamma). p53i9 is identical to p53beta. We identified also an internal promoter in the intron4 of the human p53 gene that lead to expression of p53 protein deleted of the transactivation domain (delta133p53). Thus, p53 gene expresses nine p53 protein isoforms due alternative splicing, alternative promoter usage and alternative initiation of translation as illustrated below. p53 proteins can start at any one of three different methionines (1, 40 and 133) and have three alternate C-termini, normal, beta or gamma. p53 mRNA variants are expressed in a wide range of normal human tissues but in a tissue specific-manner, suggesting that their expressions are regulated.
Crucially we have made antibodies to the new epitope created by the β splice. We used it to establish that p53β binds preferentially to bax and p21 promoters rather than MDM2 promoter, while p53 binds preferentially to MDM2 and p21 promoters rather than bax promoter. p53β enhances p53 transcriptional activity on bax promoter after cellular stress (Actinomcyin D) but has no effect on p21 promoter. Moreover, we establish also that Δ133p53 inhibits p53 transcriptional activity and p53-mediated apoptosis. This suggests that p53 isoform may modulate p53 transcriptional activity and tumour suppressor activity.
In a pilot study, we determine that p53 isoforms are differentially express in breast tumours compared to normal tissue. These results suggest that the expression or loss of expression of certain p53 isoforms could impair p53 function in cells that do not harbor inactivating mutations of the parental p53 gene. Thus, an imbalance in expression of the different isoforms in breast tumours could perturb p53 function and play a key role in the development of cancer (Bourdon et al., Genes Dev. 2005 Sep 15;19(18):2122-37).
Consistent with this hypothesis, we just reported that p53 isoforms could be involved in Acute Myeloid Leukemia where only 10% of the cases express mutant p53. (Anensen N et al,.Clin Cancer Res. 2006 Jul 1;12(13):3985-92.)

Scotin a p53 inducible protein that induces cell death

The p53 dependent stress responses are dependent on the transcriptional activation function of p53 that makes the identification and analysis of p53 induced genes of paramount importance. Most p53 target genes were identified using cell lines models which derived from transformed or tumours cells. However, cell lines have been growing for decades onto plastic Petri dish under non-physiological conditions. It is very likely that cell lines have lost most of their ability to induce programmed cell death (apoptosis). Therefore, they may not constitute the best models to identify pro-apoptotic gene and apoptotic pathways. To increase the likelihood to identify new p53-inducible pro-apoptotic genes, Jochen Renzing, Ph.D student in Prof David Lane’s lab, took advantage of the p53 KO mouse model to compare, by differential display, the expression of genes in spleen or thymus of normal and p53 nullizygote mice after -irradiation of whole animals. Spleen and thymus cells die massively by apoptosis in a p53-dependent manner after ionising radiation.
Thus, Jochen identified 48 genes differentially regulated after ionising radiation. When I joined David Lane’s lab, I followed up Jochen’s project. I focused on one up-regulated gene that I named Scotin. I cloned the human and mouse Scotin genes and established that they are directly transactivated by p53. Scotin protein has the structure of a transmembrane receptor of type I with a signal sequence, a cysteine domain, a transmembrane domain and a proline/tyrosine domain that could be involved in cell signalling. No further protein domain homology could be identified. Interestingly, the Scotin protein is localised to the endoplasmic reticulum (ER) and the nuclear membrane.
We developed polyclonal and monoclonal antibodies to mouse and human Scotin proteins. Scotin can induce apoptosis independently of p53 in a caspase dependent manner. Inhibition of endogenous Scotin expression increases resistance to p53-dependent apoptosis induced by DNA-damage indicating that Scotin plays a significant role in p53-dependent apoptosis. The discovery of Scotin brings to light a role of the endoplasmic reticulum in p53-dependent apoptosis (Bourdon et al., 2002, J Cell Biol;158(2):235-46).
We patented Scotin gene in 2002: licence number: WO 02/068465 entitled Novel p53-inducible protein, Scotin

Association with Inserm U589

We are developing novel recombinant adenoviruses for Scotin, p53 and other genes to develop gene therapy in association with the laboratory of Anne-Catherine Prats in Toulouse (Inserm). AC Prats’ laboratory has also demonstrated that p53 is able to regulate expression of angiogenic growth factor FGF-2 at the translational level. p53 binds to FGF2 Internal Ribosomal Entry Site (IRES) and inhibits FGF2 translation. We are studying also the role of p53 isoforms on FGF2 expression and IRES-dependent translation.

Link with Toulouse Laboratory

Mr Kenneth Fernandes: Senior Research Assistant
Ms Alexandra Diot: Research Assistant

PhD Students

Ms Fiona Murray-Zmijewski ; 3rd year Ph.D.
Mr Hugo Bernard: 2nd year, Joint Ph.D between Toulouse and Dundee Universities.
Ms Haley Moore: 1st year Ph.D. collaboration with Dr Frances Fuller-Pace.

Recent Book Publications

Title: p53 family pathway in cancer
Author: Jean-Christophe Bourdon and David Philip Lane
Publisher: 2nd Edition of The Cancer Handbook. JOHN WILEY & SONS LIMITED

Recent Journal Publications

Kaori Fujita, Abdul M. Mondal, Izumi Horikawa, Giang H. Nguyen, Kensuke Kumamoto, Jane J. Sohn, Elise D. Bowman, Ewy A. Mathe, Aaron J. Schetter, Sharon R. Pine, Helen Ji, Borivoj Vojtesek, Jean-Christophe Bourdon, David P. Lane and Curtis C. Harris. p53 isoforms, D133p53 and p53b, are endogenous regulators of replicative cellular senescence. Nat Cell Biol. 2009 Sep;11(9):1135-42.

J.Chen, S.Meng Ng, C. Chang, Z.Zhang, JC. Bourdon, D. P Lane and J. Peng. p53 isoform ∆113p53 is a p53 target gene that antagonizes p53 apoptotic activity via BclxL activation in zebrafish. Genes Dev. 2009 Feb 1;23(3):278-90.

Zocchi L, Bourdon JC, Codispoti A, Knight R, Lane DP, Melino G, Terrinoni A. Scotin: A new p63 target gene expressed during epidermal differentiation. Biochem Biophys Res Commun. 2008 Mar 7;367(2):271-6.

Bourdon JC. p53 Family isoforms. Curr Pharm Biotechnol. 2007 Dec;8(6):332-6. (cited 8, Nov 2009).

Draeby I, Woods YL, la Cour JM, Mollerup J, Bourdon JC, Berchtold MW. The calcium binding protein ALG-2 binds and stabilizes Scotin, a p53-inducible gene product localized at the endoplasmic reticulum membrane. Arch Biochem Biophys. 2007 Nov 1;467(1):87-94. (cited 4, Nov 2009).

JC Bourdon. p53 and its isoforms in cancer. Br J Cancer. 2007 Jul 31;97(3):277-82. Epub 2007 Jul 17. (cited 35, Nov 2009).

Ebrahimi M, Boldrup L, Coates PJ, Wahlin YB, Bourdon JC, Nylander K. Expression of novel p53 isoforms in oral lichen planus. Oral Oncol. 2007 Apr 4; (cited 4, Nov 2009).

Boldrup L, Bourdon JC, Coates PJ, Sjostrom B, Nylander K. Expression of p53 isoforms in squamous cell carcinoma of the head and neck. Eur J Cancer. 2007 Feb;43(3):617-23. (cited 17, Nov 2009).

Anensen N, Oyan AM, Bourdon JC, Kalland KH, Bruserud O, Gjertsen BT. A distinct p53 protein isoform signature reflects the onset of induction chemotherapy for acute myeloid leukemia.
Clin Cancer Res. 2006 Jul 1;12(13):3985-92.

Murray-Zmijewski F, Lane DP, Bourdon JC. p53/p63/p73 isoforms: an orchestra of isoforms to harmonise cell differentiation and response to stress. Cell Death Differ. 2006 Jun;13(6):962-72.

Dudgeon C, Kek C, Demidov ON, Saito S, Fernandes K, Diot A, Bourdon JC, Lane DP, Appella E, Fornace AJ Jr, Bulavin DV.
Tumor susceptibility and apoptosis defect in a mouse strain expressing a human p53 transgene. Cancer Res. 2006 Mar 15;66(6):2928-36.

Bourdon JC, Fernandes K, Murray-Zmijewski F, Liu G, Diot A, Xirodimas DP, Saville MK, Lane DP. p53 isoforms can regulate p53 transcriptional activity. Genes Dev. 2005 Sep 15;19(18):2122-37. Epub 2005 Aug 30.

Bates G., Nicol S., Wilson B., Bourdon JC., Wardrop J., Gregory D., Lane D., Perkins N., Fuller-Pace F. The DEAD box protein p68: a novel transcriptional co-activator of the p53 DNA damage response. EMBO J. 2005 Feb 9;24(3):543-53. Epub 2005 Jan 20.
Nagy N., Takahara M., Nishikawa J., Bourdon JC., Kis L. L., Klein G. and Klein E. Wild type p53 activates SAP expression in lymphoid cells. Oncogene. 2004 Nov 11;23(53):8563-70.

Saville MK, Sparks A, Xirodimas DP, Wardrop J, Stevenson LF, Bourdon JC, Woods YL, Lane DP. Regulation of p53 by the ubiquitin-conjugating enzymes UbcH5B/C in vivo. J Biol Chem. 2004 Oct 1;279(40):42169-81.

Xirodimas D., Saville M., Bourdon JC, Hay R and Lane D. P.
MDM2-mediated neddylation of p53 inhibits its transcriptional activity. Cell. 2004 Jul 9;118(1):83-97.

Paitel E, Sunyach C, Alves da Costa C, Bourdon JC, Vincent B, Checler F. Primary cultured neurons devoid of cellular prion display lower responsiveness to staurosporine through the control of p53 at both transcriptional and post-transcriptional levels. J Biol Chem. 2004 Jan 2; 279(1): 612-8.

Tullo A., Mastropasqua G., Bourdon JC, Centonze P., Gostissa M, Costanzo A, Levrero M, Del Sal G., Saccone C. and Sbisa E. Adenosine Deaminase, a key enzyme in DNA precursors control, is a new p73 target. Oncogene. 2003 Nov 27; 22(54): 8738-48.

Bourdon JC, De Laurenzi V., Melino G. and Lane D. p53: 25 years of research and more questions to answer. Cell Death Differ. 2003 Apr;10(4):397-9.

Bourdon JC., Renzing J., Robertson P., Fernandes K. and Lane D.P. Scotin, a novel ER-located pro-apoptotic protein, is directly transactivated by p53. J Cell Biol. 2002 Jul 22;158(2):235-46.

Deguin-Chambon V., Jullien M., Vacher M., May E. and Bourdon JC. Direct transactivation of the c-Ha-RAS gene by p53 - Evidence for its requirement for p53 transcriptional activity and p53-mediated apoptosis. Oncogene, 2000 Nov 19 (51): 5831- 41.

Munsch D, Watanabe-Fukunaga R, Bourdon JC, Nagata S, May E, Yonish-Rouach E, Reisdorf P. Human and mouse Fas (APO-1/CD95) death receptor genes each contain a p53-responsive element that is activated by p53 mutants unable to induce apoptosis. J Biol Chem. 2000 Feb 11; 275(6):3867-72.

Nylander K, Bourdon JC, Bray SE, Gibbs NK, Kay R, Hart I, Hall PA. Transcriptional activation of tyrosinase and TRP-1 by p53 links UV irradiation to the protective tanning response. J Pathol. 2000 Jan; 190(1): 39-46.

Miro F, Lelong JC, Pancetti F, Roher N, Duthu A, Plana M, Bourdon JC, Bachs O,May E,Itarte E. Tumour suppressor protein p53 released by nuclease digestion increases at the onset of rat liver regeneration. J Hepatol. 1999 Aug; 31(2):306-14.

Bourdon JC., Deguin-Chambon V., Lelong J-C., Dessen P., May P., Debuire B. and May E. Further characterisation of the p53-responsive element –identification of new candidate genes for transactivation by p53. Oncogene, 14: 85-94 (1997).

Bourdon JC., D'Errico A., Paterlini P., Grigioni W.F., May E., Debuire B. P53 protein accumulation in relation to gene mutation in european hepatocellular carcinomas. Gastroenterology, 106: 1176-1182 (1995).