The 2005 Lectures in Biology: Programmed Cell Death and Cell Signaling
Francois Jacob, one of the pioneers of molecular biology, once said "the dream of every cell is to become two cells". It must be the cell's worst nightmare to succumb to death. Yet, in addition to their wonderful capacity to replicate, cells also encapsulate a deadly potential for self destruction.
The human body consists of hundreds of cell types, all originating from the tiny fertilized egg. During the embryonic and fetal periods, the number of cells increases dramatically. Cells mature and become specialized to form the various tissues and organs of the body. Large numbers of cells are also constantly generated in the adult body. Cell death is a normal process, both in the fetus and adult, and contributes to the maintenance of the appropriate number of cells in the tissues as well as in pattern formation. In an adult human being, more than a thousand billion cells are created every day. At the same time, an equal number of cells die through a "suicide process". This delicate, controlled elimination of cells is called programmed cell death. Naturally occurring, programmed cell death is often referred to as apoptosis and appears to be a universal feature of animal development. Abnormalities in programmed cell death have been associated with a broad variety of human diseases, including certain cancers and neurodegenerative disorders.
When developmental biologists first described programmed cell death, they noted that cell death was necessary for proper development, for example when tadpoles undergo metamorphosis to become adult frogs. In the human fetus, the interdigital mesoderm initially formed between fingers and toes is removed by programmed cell death. The vast excess of neuronal cells present during the early stages of brain development is also eliminated by the same mechanism.
How do cells decide to die? How is death orchestrated? The seminal breakthrough in our understanding of programmed cell death was made by H. Robert Horvitz this year's Onassis Lectures in Biology Keynote Speaker. He, together with Sydney Brenner and John Sulston were awarded the 2002 Nobel Prize in Physiology or Medicine for their discoveries concerning the genetic regulation of organ development and programmed cell death. By establishing and using the nematode Caenorhabditis elegans as an experimental model system, possibilities were opened to follow cell division and differentiation from the fertilized egg to the adult. Detailed studies in this simple model organism demonstrated that 131 of totall 1090 cells die reproducibly during development, and that this natural cell death is controlled by a unique set of genes. The discoveries are important for medical research and have shed new light on the pathogenesis of many diseases.
Understanding the molecular basis of cell death is of paramount importance to all aspects of life. This year's Onassis Lecture Series on Biology will address the phenomenon of cell death at different levels of complexity reflected in the wide expertise of the invited speakers. The spectrum of the Lectures will be broad, providing the foundations as well as the latest concepts in this field of research.
Prof., Massachussets Institute of Technology
Nobel Prize (2002) in Medicine
Jean Claude Ameisen
Prof. of Immunology, Paris 7 University, Xavier Bichat School of Medicine
Assoc. Prof., University of Pennsylvania
Prof., Columbia University College of Physicians and Surgeons
Prof., University of Zurich, Switzerland
Senior Researcher, Neurobiology, IIBEAA, Academy of Athens
Principal Investigator, Institute of Molecular Biology and Biotechnology, FORTH