Member, Whitehead Institute
Associate Professor of Biology, MIT
Howard Hughes Medical Institute Early Career Scientist
Regeneration of tissues and organs is one of the great unsolved mysteries of biology. Whitehead Member Peter W. Reddien works to shed light on that mystery through research on the planarian Schmidtea mediterranea, a flatworm with regenerative powers that have captured the imagination of biologists for more than a century.
Planaria can reproduce either sexually or asexually. Asexual animals reproduce by dividing into two, with both head and tail fragments regrowing into complete animals. All planaria also can accomplish this feat if cut into two surgically. New tissues and organs are created by neoblasts—adult stem cells that share certain characteristics with embryonic stem cells and can differentiate into essentially all cells found in adult animals. A similar process occurs in normal intact adults, in which neoblast progeny cells continually replace aged cells. Additionally, if nutrition is limited, planaria can exhibit “de-growth”—eliminating cells while maintaining the form and function of the various organ systems of the animals. The genetic and molecular mechanisms underlying these capabilities are almost completely unknown.
Reddien is working to create a body of knowledge and research tools that will establish the planarian as a model organism with which to study the molecular genetics of regeneration. He and co-workers recently developed methods for high-throughput RNA interference (RNAi), which employs customized RNAs to silence production of proteins from a given gene. Exploiting these methods, Reddien then led the first large-scale study of gene function in planaria, discovering multiple genes needed for regeneration.
In addition to tackling the challenges of regeneration, his work should aid a more general understanding of stem cells. Recently, Reddien’s lab discovered that the gene Smed-beta-catenin-1 is crucial in determining head-to-tail polarity–whether a planarian, when cut, will produce a head or tail at a particular site. These findings could help to explain how regenerating animals “know” which missing tissues to make.
Reddien joined Whitehead Institute in 2005. He obtained his PhD in biology from Massachusetts Institute of Technology, and completed his undergraduate studies in molecular biology at the University of Texas at Austin.
- Fellow, Helen Hay Whitney Foundation (2003)
- Rita Allen Scholar Award (2006)
- Searle Scholar Award (2006)
- Smith Family Scholar Award (2006)
- Keck Distinguished Young Scholar (2008)
- Howard Hughes Medical Institute (HHMI) Early Career Scientist (2010)
- Led the first large-scale study of gene function during regeneration in planarian flatworms