Biomedical subjects

Pierre Golstein

Publications and source records attributed to Pierre Golstein.

9 recordsLinked to original sources

PubMed2006

Cell death by necrosis: towards a molecular definition.

Necrosis has been defined as a type of cell death that lacks the features of apoptosis and autophagy, and is usually considered to be uncontrolled. Recent research suggests, however, that its occurrence and course might be tightly regulated. After signaling- or damage-induced lesions, necrosis can include signs of controlled processes such as mitochondrial dysfunction, enhanced generation of reactive oxygen species, ATP depletion, proteolysis by calpains and cathepsins, and early plasma membrane rupture. In addition, the inhibition of specific proteins involved in regulating apoptosis or autophagy can change the type of cell death to necrosis. Because necrosis is prominent in ischemia, trauma and possibly some forms of neurodegeneration, further biochemical comprehension and molecular definition of this process could have important clinical implications.

Animals↗

PubMed2006

From autophagic to necrotic cell death in Dictyostelium.

Among unusual models to study cell death mechanisms, the protist Dictyostelium is remarkable because of its strategic phylogenetic position, with early emergence among eukaryotes and unicellular/multicellular transition, and its very favorable experimental and genetic flexibility. Dictyostelium shows developmental vacuolar cell death, and in vitro monolayer approaches revealed both an autophagic vacuolar and a necrotic type of cell death. These are described in some detail, as well as implications and future prospects.

Animals↗

PubMed2006

Cell death in unusual but informative and beautiful model organisms.

Cancer depends on cell death. It can emerge when cell death is deficient, and it could be treated through cancer-cell-specific induction of cell death. However, our understanding of cell death is still incomplete. While a few classical animal models have helped greatly in this respect, more may be learnt from non-classical model organisms from all eukaryotic kingdoms. We describe in this volume some of these non-classical models of cell death, which are at least potentially scientifically informative and often aesthetically pleasing.

Animals↗

PubMed2006

How to assess and study cell death in Dictyostelium discoideum.

In this chapter, we describe how to conveniently demonstrate, assess, and study cell death in Dictyostelium through simple cell culture, clonogenic tests, and photonic (with the help of staining techniques) and electronic microscopy. Cell death can be convniently generated using minor modifications of the monolayer technique of Rob Kay et al., and either wild-type HMX44A Dictyostelium cells or the corresponding atg1- autophagy gene mutant cells. Methods to follow cell death qualitatively and quantitatively facilitate detailed studies of vacuolar death in wild-type cells and of nonvacuolar, "condensed" death in atg1- mutant cells.

Animals↗

PubMed2005

[Genetic approaches to molecular mechanisms of programmed cell death in Dictyostelium].

Caspase-independent cell deaths have been observed in many species including the human. However, the molecular mechanisms which govern them are largely unknown. Our present work makes use of a model organism, the protist Dictyostelium discoideum, which displays a caspase-independent cell death during its development. In rich medium, Dictyostelium multiplies vegetatively as a unicellular organism, but in starvation conditions, Dictyostelium cells aggregate, differentiate and morphogenize into a multicellular structure, called sorocarp, containing a mass of spores supported by a stalk. Cells in the stalk are considered dead on the basis of non-regrowth in a rich medium and are vacuolized. This programmed cell death is therefore developmental and vacuolar, and in addition, caspase-independent since the Dictyostelium genome does not contain caspases genes. In order to study in detail this cell death without induction of development, an in vitro experimental protocol has been adopted, which enabled us to describe the cascade of morphological events during this cell death. An insertional mutagenesis approach, followed by appropriate selection or screening of mutants potentially resistant to death, attempted at establishing the cascade of molecular events leading to vacuolar death of Dictyostelium cells. A better understanding of alternative death pathways may allow to control different types of cell deaths in the cases of cancers or neurodegenerative diseases. In this short review, we will discuss briefly some generalities about the development of Dictyostelium in starvation conditions, and we will focus on the course of programmed cell death in Dictyostelium and on the genetic tools used to elucidate the corresponding molecular mechanisms.

Animals↗

PubMed2004

Autophagy gene disruption reveals a non-vacuolar cell death pathway in Dictyostelium.

Types of cell death include apoptosis, necrosis, and autophagic cell death. The latter can be defined as death of cells containing autophagosomes, autophagic bodies, and/or vacuoles. Are autophagy and vacuolization causes, consequences, or side effects in cell death with autophagy? Would control of autophagy suffice to control this type of cell death? We disrupted the atg1 autophagy gene in Dictyostelium discoideum, a genetically tractable model for developmental autophagic vacuolar cell death. The procedure that induced autophagy, vacuolization, and death in wild-type cells led in atg1 mutant cells to impaired autophagy and to no vacuolization, demonstrating that atg1 is required for vacuolization. Unexpectedly, however, cell death still took place, with a non-vacuolar and centrally condensed morphology. Thus, a cell death mechanism that does not require vacuolization can operate in this cell death model showing conspicuous vacuolization. The revelation of non-vacuolar cell death in this protist by autophagy gene disruption is reminiscent of caspase inhibition revealing necrotic cell death in animal cells. Thus, hidden alternative cell death pathways may be found across kingdoms and for diverse types of cell death.

Animals↗

PubMed2003

Developmental cell death in dictyostelium does not require paracaspase.

Apoptotic cell death often requires caspases. Caspases are part of a family of related molecules including also paracaspases and metacaspases. Are molecules of this family generally involved in cell death? More specifically, do non-apoptotic caspase-independent types of cell death require paracaspases or metacaspases? Dictyostelium discoideum lends itself well to answering these questions because 1) it undergoes non-apoptotic developmental cell death of a vacuolar autophagic type and 2) it bears neither caspase nor metacaspase genes and apparently only one paracaspase gene. This only paracaspase gene can be inactivated by homologous recombination. Paracaspase-null clones were thus obtained in each of four distinct Dictyostelium strains. These clones were tested in two systems, developmental stalk cell death in vivo and vacuolar autophagic cell death in a monolayer system mimicking developmental cell death. Compared with parent cells, all of the paracaspase-null cells showed unaltered cell death in both test systems. In addition, paracaspase inactivation led to no alteration in development or interaction with a range of bacteria. Thus, in Dictyostelium, vacuolar programmed cell death in development and in a monolayer model in vitro would seem not to require paracaspase. To our knowledge, this is the first instance of developmental programmed cell death shown to be independent of any caspase, paracaspase or metacaspase. These results have implications as to the relationship in evolution between cell death and the caspase family.

Animals↗

PubMed2003

Dictyostelium cell death: early emergence and demise of highly polarized paddle cells.

Cell death in the stalk of Dictyostelium discoideum, a prototypic vacuolar cell death, can be studied in vitro using cells differentiating as a monolayer. To identify early events, we examined potentially dying cells at a time when the classical signs of Dictyostelium cell death, such as heavy vacuolization and membrane lesions, were not yet apparent. We observed that most cells proceeded through a stereotyped series of differentiation stages, including the emergence of "paddle" cells showing high motility and strikingly marked subcellular compartmentalization with actin segregation. Paddle cell emergence and subsequent demise with paddle-to-round cell transition may be critical to the cell death process, as they were contemporary with irreversibility assessed through time-lapse videos and clonogenicity tests. Paddle cell demise was not related to formation of the cellulose shell because cells where the cellulose-synthase gene had been inactivated underwent death indistinguishable from that of parental cells. A major subcellular alteration at the paddle-to-round cell transition was the disappearance of F-actin. The Dictyostelium vacuolar cell death pathway thus does not require cellulose synthesis and includes early actin rearrangements (F-actin segregation, then depolymerization), contemporary with irreversibility, corresponding to the emergence and demise of highly polarized paddle cells.

Actins↗

PubMed2003

Cell-death alternative model organisms: why and which?

Classical model organisms have helped greatly in our understanding of cell death but, at the same time, might have constrained it. The use of other, non-classical model organisms from all biological kingdoms could reveal undetected molecular pathways and better-defined morphological types of cell death. Here we discuss what is known and what might be learned from these alternative model systems.

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