Programmed cell death during animal development.

The formation of the hand during embryogenesis, the peeling of sunburned skin and the tremor associated with Parkinson's disease all result from a common process: cell death. Cell death occurs throughout the life span of the organism and represents the ultimate differentiative decision made by cells. Insight into the process of cell death will not only contribute to our understanding of basic developmental issues, but will also facilitate the development of therapeutic interventions that could alter the course of disease. Since all cells have the genetic machinery required to commit suicide, the ability to initiate it in a lineage-specific, non-inflammatory manner would allow for the irradication of specific cancers. Alternatively, inhibition of cell death pathways could rescue valuable but condemned cells, such as HIV infected CD4+ T cells or dopaminergic neurons in Parkinson's disease. The goal of this chapter is to provide both an overview of the basic principles that govern the cellular and molecular mechanisms mediating cell death, as well as serve as a reference of known examples of PCD and the genes that mediate this process.