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Principal Investigator

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2006, Ph.D. 'Biology, Medicine and Health', option Neurosciences; University of Caen, UMR CNRS 6185, Centre CYCERON (France)
January 2007 to June 2012, Postdoc in François Guillemot’s lab, National Institute for Medical Research (London, UK)

Expertise: neurogenesis, RhoGTPases, neuronal development, Rnd proteins

24 publication(s) since Février 2005:

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The indicated IF have been collected by the Web of Sciences in

01/07/2006 | J Cell Sci   IF 4.5
Synergistic effects of CoCl(2) and ROCK inhibition on mesenchymal stem cell differentiation into neuron-like cells.
Pacary E , Legros H , Valable S , Duchatelle P , Lecocq M , Petit E , Nicole O , Bernaudin M

Bone-marrow-derived mesenchymal stem cells (MSCs) constitute an interesting cellular source to promote brain regeneration after neurodegenerative diseases. Recently, several studies suggested that oxygen-dependent gene expression is of crucial importance in governing the essential steps of neurogenesis such as cell proliferation, survival and differentiation. In this context, we analysed the effect of the HIF-1 (hypoxia inducible factor-1) activation-mimicking agent CoCl(2) on MSCs. CoCl(2) treatment increased the expression of the anti-proliferative gene BTG2/PC3 and decreased cyclin D1 expression. Expression of HIF-1alpha and its target genes EPO, VEGF and p21 was also upregulated. These changes were followed by inhibition of cell proliferation and morphological changes resulting in neuron-like cells, which had increased neuronal marker expression and responded to neurotransmitters. Echinomycin, a molecule inhibiting HIF-1 DNA-binding activity, blocked the CoCl(2) effect on MSCs. Additionally, by using Y-27632, we demonstrated that Rho kinase (ROCK) inhibition potentiated CoCl(2)-induced MSC differentiation in particular into dopaminergic neuron-like cells as attested by its effect on tyrosine hydroxylase expression. Altogether, these results support the ability of MSCs to differentiate into neuron-like cells in response to CoCl(2), an effect that might act, in part, through HIF-1 activation and cell-cycle arrest, and which is potentiated by inhibition of ROCK.

The aim of the present study is to better understand oxygen-sensitive adaptative pathways underlying the hypoxic preconditioning-induced protection of the brain against ischemia. Using oligonucleotide microarrays, we examined the brain genomic response of adult mice following hypoxia preconditioning (8% O2 for 1 or 6 h of hypoxia with reoxygenation 12, 18, 24 h or 72 h) and ischemia (6 h), preceeded (tolerant state) or not, by preconditioning. Real-time PCR was used to validate the results. Most gene expression increases occurred during hypoxia, including those of HIF-1-dependent genes (RTP801, AM, VEGF, p21, GLUT-1), early response genes (IER3) and transcriptional factors (ATF3, C/EBPdelta). A second wave of changes occurred 24 h after reoxygenation (S100A5, TH, Calretinin, PBX3). A third one occurred during ischemia itself, revealing that hypoxic preconditioning modifies the brain genomic response to ischemia. In addition, we show that some identical genes are overexpressed by hypoxia in both neonatal and adult brains (VEGF, EPO, GLUT-1, AM, MTs, C/EBPdelta).

2006 | Neurodegener Dis   IF 2.8
Erythropoietin, a cytoprotective and regenerative cytokine, and the hypoxic brain.
Pacary E , Petit E , Bernaudin M

Hypoxia and ischemia in the brain often result in brain dysfunctions and neuronal death during both the neonatal and adult periods. Though the mechanisms contributing to brain injury secondary to hypoxia-ischemia are more clearly defined, there are still no pharmacological treatments available to reduce cell death in the ischemic brain. This review highlights the beneficial effects of hypoxia-inducible factors, such as the transcriptional factor hypoxia-inducible factor-1 and its target genes, as both cytoprotective and regenerative factors, and focuses in particular on one of the most well-known: erythropoietin. Altogether, the data presented in this review suggest that further insights into the role of hypoxia-inducible factors would help develop promising strategies to improve the outcome of hypoxia/ischemia-related brain pathologies.

01/02/2005 | Clin Cancer Res   IF 8.9
Expression of erythropoietin and erythropoietin receptor in non-small cell lung carcinomas.
Dagnon K , Pacary E , Commo F , Antoine M , Bernaudin M , Bernaudin JF , Callard P

PURPOSE: Expression of erythropoietin (Epo) and its receptor (Epo-R) has been shown in various normal and neoplastic nonhematopoietic tissues. This study, in non-small cell lung carcinoma, was designed to investigate the previously unreported expression of Epo and Epo-R as well as hypoxia-inducible factor-1alpha (HIF-1alpha), which is known to control Epo expression. EXPERIMENTAL DESIGN: Samples from lung squamous cell carcinomas (n = 17) and adenocarcinomas (n = 12) were obtained from patients undergoing curative surgery. mRNA transcripts of Epo, Epo-R, soluble Epo-R (sEpo-R), HIF-1alpha, and factor inhibiting HIF-1 (FIH-1) were evaluated by reverse transcription-PCR, whereas localization of Epo, Epo-R, and HIF-1alpha was assessed by immunohistochemistry. RESULTS: Epo, Epo-R, sEpo-R, HIF-1alpha, and FIH-1 transcripts were detected by reverse transcription-PCR in all samples tested, but with heterogeneous levels of expression for Epo, Epo-R, and sEpo-R. Coordinated levels of mRNA were observed for HIF-1alpha and FIH-1.Epo was detected in carcinomatous cells by immunohistochemistry in 50% of samples and Epo-R was detected in 96% of samples. Co-expression of Epo and Epo-R was observed on contiguous sections from 50% of tumors. HIF-1alpha was immunolocalized in 80% of non-small cell lung carcinomas. CONCLUSION: Epo-R was expressed in almost all samples and Epo was expressed in one half of samples on immunohistochemistry and in 100% of samples by mRNA detection, suggesting a potential paracrine and/or autocrine role of endogenous Epo in non-small cell lung carcinoma. The detection of stabilized HIF-1alpha suggests a possible role in Epo expression. Moreover, in the light of these results, the potential interactions between therapeutic recombinant Epo and the putative neoplastic Epo/Epo-R signaling pathways must be considered.