Stem cell pluripotency factor regeneration

DEVELOPMENTAL DYNAMICS 238:1613–1616, 2009

PATTERNS & PHENOTYPES

Expression of Stem Cell Pluripotency Factors During Regeneration in Newts
Nobuyasu Maki,1† Rinako Suetsugu-Maki,1† Hiroshi Tarui,2 Kiyokazu Agata,3 Katia Del Rio-Tsonis,4 and Panagiotis A. Tsonis1*

In this study, we present data indicating that mammalian stem cell pluripotency-inducing factors are expressed during lens andlimb regeneration in newts. The apparent expression even in intact tissues and the ensued regulation during regeneration raises the possibility that these factors might regulate tissuespecific reprogramming and regeneration. Furthermore, these factors should enable us to understand the similarities and differences between animal regeneration in the newt and stem cell strategies in mammals.Developmental Dynamics 238:1613–1616, 2009. © 2009 Wiley-Liss, Inc. Key words: newt regeneration; transdifferentiation; stem cell; pluripotency factors Accepted 21 March 2009

INTRODUCTION
Some amphibians and especially adult newts can regenerate several tissues, organs, or even body parts. Newts achieve this remarkable process by transdifferentiation of the terminally differentiated tissues at thesite of tissue removal (Sanchez Alvarado and ´ Tsonis, 2006). Obviously, the newt cells have to be reprogrammed and then differentiate to cells that constitute the lost tissue. One of the most clear-cut cases is that of lens regeneration where after lentectomy the pigment epithelial cells (PECs) of the tip of the dorsal iris dedifferentiate and then form the lost lens. Importantly, the ventral irisPECs are not able to contribute to regeneration (Del RioTsonis and Tsonis, 2003). Recently, it

has been shown that differentiated mammalian cells, including human, can be also reprogrammed to become induced pluripotent stem cells (iPSCs) that can subsequently differentiate to different tissues. This reprogramming is mediated by inducing the expression of four factors, Oct4, Sox-2, c-myc, andKlf4. Another factor, nanog, seems to be also important (Takahashi and Yamanaka, 2006; Takahashi et al., 2007; Yu et al., 2007; Okita et al., 2007; Wernig et al., 2007). All these are transcriptional factors expressed in embryonic stem cells. The critical question that arises from these studies is: Does reprogramming that mediates the formation iPSCs share any similarities to reprogramming duringregeneration in newts?

There is no evidence indicating that newt cells reprogram to pluripotency, but ample evidence exists indicating that differentiated newt cells do change their genetic activity to transdifferentiate to another cell type. To further investigate this process, we cloned and examined the expression of the above-mentioned factors during lens and limb regeneration in newts.RESULTS AND DISCUSSION
Phylogenetic tree analysis confirmed the identity of all five genes (Fig. 1). Based on this and the extensive sequence similarities (Supp. Fig. S1, which is available online), we are quite confident that these are true orthologs (Supp. Fig. S1). However, lack of whole newt genome sequence can-

Additional Supporting Information may be found in the online version of thisarticle. 1 Department of Biology and Center for Tissue Regeneration and Engineering at Dayton, University of Dayton, Dayton, Ohio 2 RIKEN Center for Developmental Biology, Kobe, Japan 3 Department of Biophysics Kyoto University, Kyoto, Japan 4 Department of Zoology, Miami University, Oxford, Ohio Grant sponsor: NIH; Grant number: EY10540. † Drs. Maki and Suetsugu-Maki contributed equally to this work.*Correspondence to: Panagiotis A. Tsonis, Department of Biology and Center for Tissue Regeneration and Engineering at Dayton, University of Dayton, Dayton, OH 45469-2320. E-mail: panagiotis.tsonis@notes.udayton.edu DOI 10.1002/dvdy.21959 Published online 20 April 2009 in Wiley InterScience (www.interscience.wiley.com).

© 2009 Wiley-Liss, Inc.

Fig. 1. Phylogenetic tree analysis of all cloned...