Ricerc@Sapienza

The myogenic factor MyoD regulates a complex program of gene expression involving a high number of muscle specific genes and cell cycle regulators. The MyoD-dependent induction of the cell cycle inhibitor p57 presents a complex and multilevel regulation. We previously found that MyoD causes the release of a repressive chromatin loop, mediated by CTCF, between the promoter of p57 and a 150 kb-distant regulatory element, KvDMR1.
Poly(ADP-ribosyl)ation (PARylation) is a post-translational modification of various proteins and participates in the regulation of chromatin structure during DNA repair. PARP1 also regulates transcription through complex mechanisms not completely understood. It has been reported that CTCF physically interacts with and is a target of the poly(ADP-ribose)polymerase PARP1, whose activity is required for CTCF-mediated long-range chromatin insulation. Moreover, increasing evidence is accumulating that PARP1 and PARylation modulate the activity of several chromatin modifying enzymes. We have recently observed that PARP1 is required for keeping p57 under control, that PARP1 binds to KvDMR1 and that MyoD phsically interacts with PARP1. Moreover, preliminary results suggest that PARP1 also affects some muscle-specific genes.
In the present project I plan to investigate the role of PARP1 activity in p57 regulation, through the following tasks:
- Analyse the chromatin accumulation of Poly(ADP)ribose (PAR) and histone modifications on the p57 regulatory regions during differentiation in the presence and in the absence of PARP1.
- Determine the PARylation status of CTCF during differentiation
- Analyze the effects of PARP inhibitors on p57 expression and on the three-dimensional structure of the locus.
- Determine the role of MyoD in PARP1 activation
This study will have a scientific impact not only in the field of the epigenetic mechanisms governing muscle differentiation, but also in the biology of transcriptional regulation by PARP1.