Programmed cell death

Abstract

Programmed cell death (PCD) occurs during development in all the animals studied so far, but the molecular basis has been recently discovered. Apoptosis is a highly organized and genetically controlled mechanism which helps in maintaining the homeostasis in multicellular organisms. This paper reviews the recent developments in the field of PCD. Emphasis has been laid on the recent developments in the Caenorhabditis elegans cell death programme. This process is well characterized by some biochemical and cytological events. Three key genes in the PCD of C. elegans have been characterized. The ced-3 and ced-4 genes function in the killing of cells while the ced-9 gene prevents this phenomenon. The ced-9 (cell death suppressor) and ced-3 (cell death inducer) genes encode proteins which share a functional and structural homology with the mammalian proto-oncogene bcl-2 and interleukin-1β converting enzyme, respectively. These findings reveal key molecules that control life and death decisions in vertebrates. Characterization of these genes has revealed that the process of PCD is evolutionarily conserved and has shed light on the molecular nature of the apoptotic machinery.