Altered mitochondria morphology and cell metabolism in Apaf1-deficient cells.

BACKGROUND: Apaf1 (apoptotic protease activating factor 1) is the central component of the apoptosome, a multiprotein complex that activates procaspase-9 after cytochrome c release from the mitochondria in the intrinsic pathway of apoptosis. Other cellular roles, including a pro-survival role, have also been described for Apaf1, while the relative contribution of each function to cell death, but also to cell homeostatic conditions, remain to be clarified. METHODOLOGY AND PRINCIPAL FINDINGS: Here we examined the response to apoptosis induction of available embryonic fibroblasts from Apaf1 knockout mice (MEFS KO Apaf1). In the absence of Apaf1, cells showed mitochondria with an altered morphology that affects cytochrome c release and basal metabolic status. CONCLUSIONS: We analysed mitochondrial features and cell death response to etoposide and ABT-737 in two different Apaf1-deficient MEFS, which differ in the immortalisation protocol. Unexpectedly, MEFS KO Apaf1 immortalised with the SV40 antigen (SV40IM-MEFS Apaf1) and those which spontaneously immortalised (SIM-MEFS Apaf1) respond differently to apoptotic stimuli, but both presented relevant differences at the mitochondria when compared to MEFS WT, indicating a role for Apaf1 at the mitochondria.

Identification of new snake venom metalloproteinase inhibitors using compound screening and rational Peptide design.

The majority of snakebite envenomations in Central America are caused by the viperid species Bothrops asper, whose venom contains a high proportion of zinc-dependent metalloproteinases that play a relevant role in the pathogenesis of hemorrhage characteristic of these envenomations. Broad metalloproteinase inhibitors, such as the peptidomimetic hydroxamate Batimastat, have been shown to inhibit snake venom metalloproteinases (SVMP). However, the difficulty in having open public access to Batimastat and similar molecules highlights the need to design new inhibitors of SVMPs that could be applied in the treatment of snakebite envenomations. We have chosen the SVMP BaP1 as a model to search for new inhibitors using different strategies, that is, screening of the Prestwick Chemical Library and rational peptide design. Results from these approaches provide clues on the structural requirements for efficient BaP1 inhibition and pave the way for the design of new inhibitors of SVMP.

Minocycline inhibits cell death and decreases mutant Huntingtin aggregation by targeting Apaf-1.

Minocycline (7-dimethylamino-6-dimethyl-6-deoxytetracycline) is a second-generation tetracycline that can cross the blood-brain barrier and has anti-inflammatory and neuroprotective effects. The potential of minocycline as a drug for treating Huntington's disease has been studied; however, the molecular mechanism underlying the neuroprotective properties of minocycline remains elusive. In this study, we tested the hypothesis that a principal cellular target of minocycline is Apaf-1, a key protein in the formation of the apoptosome, a multiprotein complex involved in caspase activation. Minocycline binds to Apaf-1, as shown by nuclear magnetic resonance spectroscopy, and inhibits apoptosome activity in vitro and in ex vivo models. As a consequence, minocycline-treated cells as well as Apaf-1 knock-out cells are resistant to the development of mutant huntingtin-dependent protein aggregation.