lionel costa PhD student Molecular Biology and Nuclear organisation

Course and current status

Born in France, February,15-1984

status: single

Past and current position

PhD in Biological science, University of Montpellier II

2008-2011 (December)

emphasis: cell biology, epigenetic  minor: optical tool

Thesis title: Role of the endoribonuclease RNase L on the structure of chromatin (funded by French the ministry of research)

Thesis director: Dr T. Salehzada and Pr P. Gall-Borrut

2006-2008    Master cell Biology, University of Marseille II

Two training courses of 6 months in 2008 in the institute of Immunology (CIML)

Septembre 2007-February 2008The role of macrophages in the propagation of malaria (Facilparum infection)

Supervisor G. Chimini

Mars 2008-July 2008 Study of the implication of membrane nanodomains on the complexes MHC-TCR

Supervisor Y.Hammon

2003-2006 BSc (Hons) Biochemistry, University of Burgundy, Dijon.

Modules included: enzymology, biochemistry, cell biology, immunology

2002-2003 Medical school, university of Burgundy, Dijon.

1995-2002 Boarding military school, burgundy

biology A, chemistry B, maths C

1.        Costa L, Fabre O, Falgarette P, Gall-Borrut P, Mercier J, Bisbal C and Salehzada T (2011). RNase L/RLI regulates an RNA component in higher–order structure of pericentromeric heterochromatin (in preparation).

2.      Mahieu-Williame L, Falgayrettes P, Nativel L, Gall-Borrut P, Costa L, Salehzada T, Bisbal C. (2009). Near-field microscopy and fluorescence spectroscopy: application to chromosomes labelled with different fluorophores. Journal of Microscopy.

Costa L, Fabre O, Falguarette P, Gall-Borrut P, Mercier J, Ramonda M, Bisbal C and Salehzada T. Identification of a novel enzymatic pathway regulating the formation of centromeric heterochromatin in mammalian cells. EMBO Conference Series Chromatin and Epigenetics. Germany. (2011). Poster Presentation

 Costa L, Fabre O, Falguarette P, Gall-Borrut P, Mercier J, Ramonda M, Bisbal C and Salehzada T. Identification of a novel enzymatic pathway regulating the formation of centromeric heterochromatin in mammalian cells. EMBO Conference Series Nuclear Structure and Dynamics. France. (2011). Poster Presentation

Scientific summary

Brief synopsis of my thesis research:

Centromeric chromatin is organized in a highly condensed form: the heterochromatin. These DNA regions are characterized by the presence of long tandem repeats of short DNA sequences which in mouse genome are: major satellites associated with pericentromeric regions, and minor satellites associated at the primary constriction of chromosomes.

 Different protein complexes regulate and organize the heterochromatin at a centromeric level. The histone H3 variant CENP-A (CENtromere Protein A) is associated with minor satellite DNA and is essential to organize the kinetochore and therefore chromosome segregation. The heterochromatin-associated protein 1 a (HP1a) is mainly associated with pericentromeric regions (major satellite DNA). Moreover, it was recently demonstrated that an RNA component is necessary for the establishment and integrity of centromeres and particularly for HP1a localization at the pericentromeric region. These RNA are transcribed from centromeric DNA itself then processed. The requirement for RNA interference (RNAi) pathway in this process has been shown. However different studies show that RNAi implication in heterochromatin and centromeres formation in mammalian cells is not obvious. Other enzymatic pathways could be implicated in centromeric RNA cleavage and heterochromatin formation. We have studied the role of an endoribonuclease L (RNase L) as a possible regulator in the proper formation process of centromeric heterochromatin in mammalian cells.

In parallel, I studied in collaboration with a physicial laboratory, the ultrastructure of chromosomes with a Scanning Near-field Optical Microscope (SNOM). This technique is very powerful because it could capture acquisition with of resolution below 100 nm. We try to convert an exclusive physical technique into a potent biological tool.