Programmed cell death in the cellular differentiation of microbial eukaryotes.

Programmed cell death (PCD) is a ubiquitous feature of multicellular and unicellular organisms. Eukaryotic microbes use PCD to regulate the development of specialized cells and structures. Many different types of PCD occur, ranging from apoptosis-like cell death, programmed necrosis and autophagic death. An overview of cell death pathways is undertaken, highlighting new elements in the PCD molecular machinery. Examples of PCD in cellular differentiation are explored alongside evolutionary scenarios that could initiate and maintain PCD in microbes, including the evolution of multicellularity. The finding that defects in PCD can lead to antimicrobial drug resistance is also considered. Greater understanding of PCD and its role in differentiation offers new hope for discovery of therapeutic agents that manipulate endogenous cell suicide pathways.