Abstract: Series 107, Lecture 4
The Harvey Lectures Series 107 (2011—2012)
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Lecture #4: Thursday, February 16, 2012 — Time and Location
Animal Regeneration and Tissue Homeostasis Regulation: Lessons from Planarian Flatworms
Alejandro Sánchez Alvarado, PhD
Investigator, Howard Hughes Medical Institute
Professor of Neurobiology and Anatomy
Howard Hughes Medical Institute, Stowers Institute for Medical Research
Kansas City, Missouri
It is paradoxical that for many organisms (including humans), the apparent anatomical stability of their adult bodies is maintained by constant change. Under normal physiological conditions, the functions of many organs depend on the continuous destruction and renewal of their cells. Equally remarkable is the fact that the adult tissues and organs of many organisms can be fully restored after being subjected to trauma such as amputation. Hence, it appears that metazoans have evolved a series of renewal and repair mechanisms to respond to both injury and normal wear and tear in order to maintain the form and function of their body plans. As important as such mechanisms are to the survival of multicellular organisms and the obvious relevance to regenerative medicine, we know little about how these processes are effected and regulated at the cellular and molecular levels. As such, numerous questions remain unanswered, including: How do organ systems maintain their order and function while in a state of cell flux? How do animals control and coordinate the size and cell number of multiple organ systems? Does regeneration invoke embryogenesis, generic patterning mechanisms, or unique circuitry comprised of well-established patterning genes? Answering any of these questions would set a baseline from which to mechanistically dissect the problems of regeneration and tissue homeostasis. Here, I will discuss how the study of a simple metazoan, the planarian Schmidtea mediterranea, is beginning to shed light on the way adult somatic stem and differentiated cells are regulated in animals to maintain form and function and to replace missing body parts lost to injury.