Quand la forme en une autre s'en va... la mort et la sculpture du vivant

Résumé Fr En

Les concepts de «mort cellulaire programmée», de «suicide cellulaire» et d’apoptose – et l’exploration des mécanismes qui contrôlent ces phénomènes – ont bouleversé en profondeur notre compréhension du fonctionnement normal de nos corps, conduit à une réinterprétation de la pathogenèse de la plupart de nos maladies et fait naître de nouveaux espoirs thérapeutiques. Ils sont en train de modifier notre vision du vieillissement, et, à une autre échelle, de certains aspects de l’évolution du vivant. Révélant le rôle central que joue l’autodestruction dans la pérennité du vivant, ils ont transformé notre représentation des relations qu’entretiennent la vie, la mort et le temps, suggérant qu’une forme de jeu, contingent et de plus en plus complexe avec la mort – avec sa propre fin – a pu être un déterminant essentiel du long voyage qu’a accompli la vie à travers le temps et du foisonnement de nouveauté auquel elle a donné naissance.

Each of us is a heterogeneous society made up of billions of cells. It has long been thought that the death of our cells – as our own death – could only occur as a consequence of injury, damage and aging, of an ultimate inability to resist environmental assaults and the passage of time. Today we know that as long as we live, all our cells continuously produce the executioners that allow them to self-destruct within a few hours. And they can only survive as long as they receive – and remain able to perceive – the signals emitted by other cells, that allow them to repress the induction of their suicide program.This very frailty is the source of an absolute form of interdependence, linking the fate of each one of our cells to that of the collectivity of our body; and this interdependence, in turn, is the source of our complexity and our plasticity, allowing us to continuously reconstruct ourselves and adapt to new environments.A new and paradoxical view of life has emerged from these findings: life as a suspended sentence; as a constant repression of self-destruction; as the negation of a negative process. The ancient image of death as a reaper, striking from without, has progressively given way to that of a sculptor at the heart of life, at work, from within, giving birth to novelty and complexity.These concepts have led to a reinterpretation of the mechanisms involved in the development of most our diseases, providing new prospects for therapy. They are changing our understanding of the mystery of how and why we age, and, at a very different level, part of our representation of the long process of evolution that has led to our emergence, and to that of the kingdoms of life that surround us today. They have transformed our usual ideas about the relationships between life, time, and death.