Peter W. Reddien, PhD
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Member, Whitehead Institute
Associate Professor of Biology, MIT
Howard Hughes Medical Institute Early Career Scientist
617.324.4083 phone
reddien@wi.mit.edu
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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.
Selected Achievements
• 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. |
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.
Selected Publications
Gavino MA and Reddien PW. A bmp/admp regulatory circuit controls maintenance and regeneration of dorsal-ventral polarity in planarians. Curr Biol 21(4), 294-9 (2011).
Petersen CP and Reddien PW. Polarized notum activation at wounds inhibits Wnt function to promote planarian head regeneration. Science 332(6031), 852-5 (2011).
Wagner DE, Wang IE, and Reddien PW. Clonogenic neoblasts are pluripotent adult stem cells that underlie planarian regeneration. Science 332(6031), 811-6 (2011).
Wenemoser D and Reddien PW. Planarian regeneration involves distinct stem cell responses to wounds and tissue absence. Dev Biol 344(2), 979-91 (2010).
Scimone ML, Meisel J and Reddien PW. The Mi-2-like Smed-CHD4 gene is required for stem cell differentiation in the planarian Schmidtea mediterranea. Development 137(8), 1231-41 (2010).
Glazer AM, Wilkinson AW, Backer CB, Lapan SW, Gutzman JH, Cheeseman IM and Reddien PW. The Zn finger protein Iguana impacts Hedgehog signaling by promoting ciliogenesis. Dev Biol 337(1), 148-56 (2010).
Petersen CP and Reddien PW. Wnt signaling and the polarity of the primary body axis. Cell 139(6), 1056-68 (2009).
Petersen CP and Reddien PW. A wound-induced Wnt expression program controls planarian regeneration polarity. Proc Natl Acad Sci U S A 106(40), 17061-6 (2009).
Petersen CP and Reddien PW. Smed-betacatenin-1 is required for anteroposterior blastema polarity in planarian regeneration. Science 319(5861), 327-30 (2008).
Reddien PW, Newmark PA and Sanchez Alvarado A. Gene nomenclature guidelines for the planarian Schmidtea mediterranea. Dev Dyn 237(11), 3099-101 (2008).
Reddien PW, Bermange AL, Kicza AM and Sanchez Alvarado A. BMP signaling regulates the dorsal planarian midline and is needed for asymmetric regeneration. Development 134(22), 4043-51 (2007).
Reddien PW, Oviedo NJ, Jennings JR, Jenkin JC and Sanchez Alvarado A. SMEDWI-2 is a PIWI-like protein that regulates planarian stem cells. Science 310(5752), 1327-30 (2005).
Reddien PW, Bermange AL, Murfitt KJ, Jennings JR and Sanchez Alvarado A. Identification of genes needed for regeneration, stem cell function, and tissue homeostasis by systematic gene perturbation in planaria. Dev Cell 8(5), 635-49 (2005).
Reddien PW and Sanchez Alvarado A. Fundamentals of planarian regeneration. Annu Rev Cell Dev Biol 20, 725-57 (2004).
Newmark PA, Reddien PW, Cebria F and Sanchez Alvarado A. Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians. Proc Natl Acad Sci U S A 100, 11861-5 (2003).
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