[Abstract unavailable

Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death routines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the authors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the progress of this vibrant field of research.

The relevance of the mitochondrial permeability transition pore (PTP) in Ca 2؉ homeostasis and cell death has gained wide attention. Yet, despite detailed functional characterization, the structure of this channel remains elusive. Here we report on a new class of inhibitors of the PTP and on the identification of their molecular target. The most potent among the compounds prepared, Ro 68-3400, inhibited PTP with a potency comparable to that of cyclosporin A. Since Ro 68-3400 has a reactive moiety capable of covalent modification of proteins, [3 H]Ro 68-3400 was used as an affinity label for the identification of its protein target. In intact mitochondria isolated from rodent brain and liver and in SH-SY5Y human neuroblastoma cells, [ 3 H]Ro 68-3400 predominantly labeled a protein of ϳ32 kDa. This protein was identified as the isoform 1 of the voltage-dependent anion channel (VDAC). Both functional and affinity labeling experiments indicated that VDAC might correspond to the site for the PTP inhibitor ubiquinone 0 , whereas other known PTP modulators acted at distinct sites. While Ro 68-3400 represents a new useful tool for the study of the structure and function of VDAC and the PTP, the results obtained provide direct evidence that VDAC1 is a component of this mitochondrial pore.

The mechanisms by which pro-apoptotic members of the Bcl-2 family of proteins promote the release of mitochondrial factors like cytochrome c, subsequently activating the apoptotic cascade, or by which anti-apoptotic family members block this release, are still not understood. When expressed in yeast, Bcl-2 family members act directly upon conserved mitochondrial components that correspond to their apoptotic substrates in mammalian cells. Here we describe a system in which the levels of representative pro- and anti-apoptotic members of the Bcl-2 family can be regulated independently in yeast. Using this system, we have focused on the action of the anti-apoptotic family member Bcl-x(L), and have defined the quantitative relationships that underlie the antagonistic action of this protein on the lethal consequences of expression of the pro-apoptotic family member Bax. This system has also allowed us to demonstrate biochemically that Bcl-x(L) has two actions at the level of the mitochondrion. Bcl-x(L) is able to inhibit the stable integration of Bax into mitochondrial membranes, as well as hinder the action of Bax that does become stably integrated into these membranes. Taken together, our results suggest that both the functional and biochemical actions of Bcl-x(L) may be based on the ability of this molecule to disrupt the interaction of Bax with a resident mitochondrial target that is required for Bax action. Finally, we confirm that VDAC (voltage-dependent anion channel) is not required for the functional responses observed following the expression of either pro- or anti-apoptotic members of the Bcl-2 family.