title: A novel role of the hedgehog pathway in lens regeneration.
abstract: Lens regeneration in the adult newt is a classic example of replacing a lost organ by the process of transdifferentiation. After lens removal, the pigmented epithelial cells of the dorsal iris proliferate and dedifferentiate to form a lens vesicle, which subsequently differentiates to form a new lens. In searching for factors that control this remarkable process, we investigated the expression and role of hedgehog pathway members. These molecules are known to affect retina and pigment epithelium morphogenesis and have been recently shown to be involved in repair processes. Here we show that Shh, Ihh, ptc-1, and ptc-2 are expressed during lens regeneration. The expression of Shh and Ihh is quite unique since these genes have never been detected in lens. Interestingly, both Shh and Ihh are only expressed in the regenerating and developing lens, but not in the intact lens. Interfering with the hedgehog pathway results in considerable inhibition of the process of lens regeneration, including decreased cell proliferation as well as interference with lens fiber differentiation in the regenerating lens vesicle. Down-regulation of ptc-1 was also observed when inhibiting the pathway. These results provide the first evidence of a novel role for the hedgehog pathway in specific regulation of the regenerating lens.
authors.affiliation: Laboratory of Molecular Biology, Department of Biology, University of Dayton, Dayton, OH 45469-2320, USA. Panagiotis.Tsonis@notes.udayton.edu
authors.forename: Panagiotis A
authors.initials: PA
authors.lastname: Tsonis
authors.forename: M Natalia
authors.initials: MN
authors.lastname: Vergara
authors.forename: Jason R
authors.initials: JR
authors.lastname: Spence
authors.forename: Mayur
authors.initials: M
authors.lastname: Madhavan
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Kramer
authors.forename: Mindy K
authors.initials: MK
authors.lastname: Call
authors.forename: William G
authors.initials: WG
authors.lastname: Santiago
authors.forename: Jefferson E
authors.initials: JE
authors.lastname: Vallance
authors.forename: David J
authors.initials: DJ
authors.lastname: Robbins
authors.forename: Katia
authors.initials: K
authors.lastname: Del Rio-Tsonis
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine; D017931:DNA Primers; D005786:Gene Expression Regulation; D053823:Hedgehog Proteins; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007908:Lens, Crystalline / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D000072079:Patched Receptors; D012313:RNA / Q000235:genetics; D011956:Receptors, Cell Surface; D012038:Regeneration / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012455:Salamandridae / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*
chemical_list: D017931:DNA Primers; D053823:Hedgehog Proteins; D008565:Membrane Proteins; D000072079:Patched Receptors; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D012313:RNA; D001973:Bromodeoxyuridine