Role of p21^CDKN1A protein in DNA repair

Among the many factors acting in the DNA damage response, a particular place seems to be deserved to the cell cycle inhibitor p21^CDKN1A, being this protein able to participate in multiple processes, including cell cycle regulation, the transcriptional program, apoptosis, as well as DNA repair. In the latter process, the activity of p21 is mediated by its ability to interact with relevant factors such as PCNA, playing a fundamental role in nucleotide excision repair (NER), or with PARP-1 in base excision repair (BER). While in the case of BER, p21 has been shown to stimulate the binding of PARP-1 to DNA repair intermediates, the function in the NER process is still unclear. Aim of this project is to investigate whether p21 may coordinate the interaction of PCNA with multiple partners involved in the different steps of NER (DNA incision, synthesis, ligation, histone deposition).