Líneas de investigación:
1- Mecanismos de formación de aberraciones cromosómicas en células de mamífero.
2- Influencia de la estructura y dinámica de la cromatina en la inducción de daño genético.
DNA damage may lead to cell transformation,senescence, or death. Histone H2AX phosphorylation,immunodetected as γH2AX foci, is an early response to DNA damage persisting even after DNA repair. In cycling mammalian cells with canonical nuclear architecture, i.e., central euchromatin and peripheral heterochromatin, γH2AX foci map preferentially to euchromatin.
Mice retina rods are G0 cells displaying an inverted nuclear architecture 28 days after birth (P28). Rod nuclei exhibit one or two central constitutive heterochromatin chromocenters encircled by facultative heterochromatin. Euchromatin resides at the nuclear periphery, extending to the equator in cells withtwo chromocenters. To assess the impact of chromatin relocation in the localization of DNA damage, γH2AX and TUNEL foci induced ex vivo by radiomimetic bleomycin were mapped in H3K4me3 immunolabeled P28 rod nuclei. An index was established to quantify the results.
The observed topology of DNA damage in retina-differentiated rods indicates that euchromatin is damage-prone, regardless of the canonical or inverted nuclear architecture of mammalian cells.
3- Rol de la arquitectura nuclear y los dominios cromosómicos en la localización del daño genético.
4.- Poly-ADP ribosylation in health and disease. Led by Laura Lafon-Hughes.
Poly-ADP-ribose (PAR) is a polymer synthetized by poly(ADP-ribosyl) polimerases (PARPs) from NAD+ as a protein postraslational modification. It is unique in being linear or branched, reaching 400 units and having nucleic-acid-like properties. Humans harbor 17 PARPs, among which only four synthetize PAR, namely PARP-1, PARP-2, tankyrase-1 (TNKS-1) and tankyrase-2 (TNKS-2). PARP-1 is the most ancient and the best studied PARP. It is only nuclear. PARP-2 and TNKS can be localized in nuclei and cytoplasm. Interestingly, a number of pathologies including inflammatory diseases, neurodegeneration and cancer, display alterations in PARPs or PAR localization or abundance. Nuclear PARPs are known to be involved in chromatin structure, transcription and DNA repair regulation. On the other hand, only recently have emerged works suggesting new functions of cytoplasmic PARPs and PAR.
Using immunocytofluorecence and confocal microscopy, we have described the existence of PAR associated to the E-cadherin rich adherens junctions where actin microfilaments are anchored in renal epithelial cells (VERO). Cytochalasin –D induced the disassembly of the actin cytoskeleton concomitantly with the dissassembly of the PAR belt. Conversely, the tankyrase inhibitor XAV939 affected cell shape, adherence and the actin cytoskeleton.
We are currently exploring the existence of the PAR belt in mouse tissues. In addition, we have a joint project with an argentinain laboratory to deepen the role of PAR during Trypanosoma cruzi infection. We are also aiming to deepen certain studies about the role of nuclear PARILATION in the response to induced genetic damage.