Poly(ADP-ribose) polymerase-1 (PARP-1) is a chromatin-associated enzyme that is activated by DNA strand breaks and catalyzes the transfer of ADP-ribose groups from NAD to itself and other nuclear proteins. Although caspase-mediated PARP-1 cleavage occurs during almost all forms of apoptosis, the contribution of PARP-1 activation and cleavage to this cell death process remains unclear. Using immortalized fibroblasts from wild-type (PARP-1(+/+)) and PARP-1 knockout (PARP-1(-/-)) mice, and a mouse neuroblastoma cell line (N18), the role that poly(ADP-ribosyl)ation plays in Sindbis virus (SV)-induced apoptosis was examined. Robust PARP-1 activation occurred in SV-infected cells prior to morphologic changes associated with apoptotic cell death and PARP-1 activity ceased simultaneously with caspase-3 activation and PARP-1 proteolysis. PARP-1 activity was maximal before detectable DNA fragmentation, but was absent when DNA damage was most intense. SV and staurosporine-induced cell death was delayed in fibroblasts lacking PARP-1 activity, suggesting that PARP-1 activation contributes to apoptotic cell death induced by these stimuli. SV replication was not affected by lack of PARP-1 activity, but DNA fragmentation and caspase-3 activation were delayed and occurred at lower levels in PARP-1-deficient fibroblasts. Early virus-induced PARP-1 activation may represent a novel way by which cells signal to the nucleus to regulate protein function by poly(ADP-ribosyl)ation in response to virus infection.

Viral encephalitis (VE) and viral meningitis (VM) have been notifiable infectious diseases under surveillance in the Republic of Ireland since 1981. Laboratories have reported confirmed cases by detection of viral nucleic acid in cerebrospinal fluid since 2004. To determine the prevalence of these diseases in Ireland during 2005–2008, we analyzed 3 data sources: Hospital In-patient Enquiry data (from hospitalized following patients discharge) accessed through Health Intelligence Ireland, laboratory confirmations from the National Virus Reference Laboratory, and events from the Computerised Infectious Disease Reporting surveillance system. We found that the national surveillance system underestimates the incidence of these diseases in Ireland with a 10-fold higher VE hospitalization rate and 3-fold higher VM hospitalization rate than the reporting rate. Herpesviruses were responsible for most specified VE and enteroviruses for most specified VM from all 3 sources. Recommendations from this study have been implemented to improve the surveillance of these diseases in Ireland.

Tumour necrosis factor-a (TNF) receptors mediate a variety of physiological cellular effects dependent on the cell type and the signalling responses triggered by the two subtypes of TNF receptor. The role of the intracellular Ca'' ion in the TNF'S apoptotic cell death response is controversial. Here we investigated the control of intracellular Ca" concentration (measured by Fura-2 ratiometric imaging) in models of TNF-induced apoptotic cell death. KYM-I human rhabdomyosarcoma cells respond rapidly to low concentrations of TNF to undergo apoptosis. Over long time courses (> 6 h) a supramaximal concentration of TNF (50 ng/ml) was unable to alter KYM-1 cell resting [Ca'+J levels which varied between 40 and 80 nM. Maximum achievable [Ca'y, was greater than 1 pM in all cells as revealed by 1 mM ionomycin treatment. Similar results were observed in other models of TNF-induced apoptotsis, namely HeLa cells and HeLa cells overexpressing the the human type II TNF receptor subtype. These results do not support a role for TNF modulation of [Ca"], in the cytokine's induction of apoptotic cell death. 17 Cathepsin B is a target for the protection of neuronal cells by caspase inhibitor ac-WAD-cmk.Inhibition of caspases has been proposed as an approach to the treatment of neurodegenerative diseases. The capsase inhibitor ac-WAD-cmk has been found to be protective (ECSO 1pM) in oxidative stress induced cytotoxicity in the neuronal cell line HT-4 and primary neurones. However, a lack of caspase activation or match between protection and structure activity relationships, suggested that ac-YVAD-cmk has an alternative target. These studies describe the identification of an alternative target for ac-YVAD-cmk. Affinity labelling studies using iodinated or biotin-YVAD-cmk identified a target binding protein (WAD-BP) of 34kDa, that was not targeted in apoptosing in Jurkat cells. W A D -BP from cells exposed to oxidative stress and rescued with unlabelled WAD-cmk in the growth medium did not bind biotin-WAD-cmk, showing that the YVAD-BP is targeted during the rescue of the cells by ac-WAD-cmk. Competition with protease class inhibitors demonstrated the target to be a thiol protease, consistent with it being a caspase or cysteine cathepsin. The WAD-BP was isolated by affinity purification and 2D-PAGE. A proteolytic fragment was sequenced by electrospray mass spectrometry and identified the WAD-BP as cathepsin-B. Cathepsin-B inhibitors were shown to be able to compete with biotin-WADcmk for WAD-BP. These data identify cathepsin-B as a target for ac-WAD-cmk and provide evidence of a role for cathepsin-B during oxidative stress induced neurotoxicity.Apoptosis is a genetically controlled and morphologically distinct mode of cell death that is utilized by metazoan organisms to selectively target specific cells for deletion. Apoptotic cell death plays a key role in the regulation of cell numbers both during embryogenesis and in the adult.An important component of this process is a family of proteolytic enzymes called Caspases. Crucially, caspase...

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