152 research outputs found
Multiple roles of the cell cycle inhibitor p21(CDKN1A) in the DNA damage response.
No full textAmong cell cycle regulatory proteins that are activated following DNA damage, the cyclin-dependent kinase inhibitor p21(CDKN1A) plays essential roles in the DNA damage response, by inducing cell cycle arrest, direct inhibition of DNA replication, as well as by regulating fundamental processes, like apoptosis and transcription. These functions are performed through the ability of p21 to interact with a number of proteins involved in these processes. Despite an initial controversy, during the last years several lines of evidence have also indicated that p21 may be directly involved in DNA repair. In particular, the participation of p21 in nucleotide excision repair (NER), base excision repair (BER), and DNA translesion synthesis (TLS), has been suggested to occur thanks to its interaction with proliferating cell nuclear antigen (PCNA), a crucial protein involved in several aspects of DNA metabolism, and cell-cycle regulation. In this review, the multiple roles of p21 in the DNA damage response, including regulation of cell cycle, apoptosis and gene transcription, are discussed together with the most recent findings supporting the direct participation of p21 protein in DNA repair processes. In particular, spatio-temporal dynamics of p21 recruitment to sites of DNA damage will be considered together with several lines of evidence indicating a regulatory role for p21. In addition, the relevance of post-translational regulation in the fate (e.g. degradation) of p21 protein after cell exposure to DNA damaging agents will be analyzed. Both sets of evidence will be discussed in terms of the overall DNA damage response
The histone acetyliltransferase p300 is involved in the dna synthesis step of nucleotide excision repair
No full textApoptosis without DNA fragmentation in HeLa cells after photosensitization with Rose Bengal acetate: involvement of mitochondria.
No full textEvidence of poly (ADP-ribosylation) in the cockroach Periplaneta americana.
No full textPoly(ADP-ribosylation) is a post-translational modification of nuclear proteins typical of most eukaryotic cells. This process
participates in DNA replication and repakandisnlainly regulated by two enzymes, poly(ADP-ribose) polymerase, which is responsible
for the synthesis of polymers of ADP-ribose, and poly(ADP-ribose) glycohydrolase, which perfonns polymer degradation. The aim 'of this work was to investigate in the cockroach Periplaneta americana L. (Blattaria: Blattidae) the behaviour of poly(ADPribosylation). In particular, we addressed: (i) the possible modulation of poly(ADP-ribosylation) during the embryonic development; (ii) the expression of poly(ADP-ribose) polymerase and glycobydrolase in dilierent tissues; and (iii) the role of poly(ADPribosylation) during spennatogenesis. In this work we demonstrated that: (i) as revealed, by specific biochemical assays, active poly(ADP-ribose) polymerase and glycohydrolase are present exclusively in P. americana embryos at early stages of development; (ii) an activity carrying out poly(ADP-ribose) synthesis was fouod in extracts from testes; and (iii) the synthesis of poly(ADPribose) occurs preferentia1ly in differentiating spermatids/spennatozoa. CoHectively, oUI results indicate that the poly(ADP-ribosylation) process in P. americana, which is a hemimetabolous insect, displays catalytical and structural features similar to those described in the holometabolous insects and in 'mammalian cells. Furthermore,
this process appears to be modulatedduring embryonic development and spermatogenesis
Enzyme-assisted photosensitization activates diVerent apoptotic pathways in Rose Bengal acetate treated HeLa cells
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