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Abstract

Poly(ADP-ribosylation) is a post-translational modification of proteins playing a crucial role in many processes, including DNA repair and cell death. The best known poly(ADP-ribosylating) enzyme, PARP-1, is a DNA nick sensor and uses betaNAD(+) to form polymers of ADP-ribose which are further bound to nuclear protein acceptors. To strictly regulate poly(ADP-ribose) turnover, its degradation is assured by the enzyme poly(ADP-ribose) glycohydrolase (PARG). During apoptosis, PARP-1 plays two opposite roles: its stimulation leads to poly(ADP-ribose) synthesis, whereas caspases cause PARP-1 cleavage and inactivation. PARP-1 proteolysis produces an 89 kDa C-terminal fragment, with a reduced catalytic activity, and a 24 kDa N-terminal peptide, which retains the DNA binding domains. The fate and the possible role of these fragments during apoptosis will be discussed.

HMGA1 protein expression sensitizes cells to cisplatin-induced cell death

“…However, the Hmga1 mRNA expression did not significantly change (Figure 1d), suggesting that post-transcriptional or posttranslational modifications contributed to cisplatininduced downregulation of HMGA1 protein levels. As expected, we observed a 2.5-fold increase of Brca1 expression in Hmga1 À/À , with respect to parental ES cells both at protein (Figure 1c) and at RNA level Subsequently, we evaluated the apoptotic rate of cisplatin-treated ES cells by analysing the cleavage of the poly ADP-ribose polymerase protein (PARP), which represents a critical molecular event when cells undergo apoptosis (Soldani and Scovassi, 2002). Exposure of WT ES cells to 25 mM cisplatin resulted in the cleavage of PARP protein, as revealed by the presence of the 85-kDa band corresponding to a cleaved form of PARP, whereas only the major band of 112 kDa, corresponding to the uncleaved PARP protein, was detected in Hmga1 À/À ES cells after the same treatment (Figure 1e), suggesting that ES cells unable to express the HMGA protein are more resistant to cisplatininduced apoptosis.…”

A Novel Aminosaccharide Compound Blocks Immune Responses by Toll-like Receptors and Nucleotide-binding Domain, Leucine-rich Repeat Proteins

“…n.s., nonspecific. tion of cellular DNA, are hallmarks of apoptosis and contribute to the irreversibility of the cell death process (49). MG-132-treated RAW264.7 cells exhibited proteolysis of PARP-1 and active caspase-3 as expected (Fig.…”

Juxtacrine Activation of Epidermal Growth Factor (EGF) Receptor by Membrane-anchored Heparin-binding EGF-like Growth Factor Protects Epithelial Cells from Anoikis While Maintaining an Epithelial Phenotype

“…Expression of Bak, Bax, Bim, Bad, and activated caspase-3 was determined using total cell lysate and antigen-specific antibodies. In addition, we examined poly(ADP-ribose) polymerase cleavage, since PARP is cleaved differentially during apoptosis versus necrosis, and generation of an 85 kDa band is a signature pattern of apoptosis (30). Although no differences were observed in the expression of Bak at all time points compared with the 0 h in either wild type or MDCK 5aa cells, expression of Bax, Bim, Bad, and caspase-3 all increased in a time-dependent manner in the wild type cells, with the highest expression of Bax and caspase-3 at 8 h of culture on polyHEMA-coated plates and maximum expression of Bad and Bim at 24 h. PARP cleavage to generate the 85-kDa fragment was highest at 8 h and was also associated with a time-dependent increase in its protein expression.…”