Molecular and cellular characterization of prominin-like molecules in urodele amphibian - A unique model to study central nervous system regeneration

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The purpose of this research program is to characterize prominin molecules in urodele amphibian axolotl and to assess whether they can be established as markers of normal and/or provoked neurogenesis in the regenerating central nervous system (CNS). As opposed to mammals, aquatic vertebrate animals have an enormous regenerative ability being able to regenerate a number of complex anatomical structures making them attractive systems for studying mechanisms underlying epimorphic regeneration. However, the cellular and molecular characterization of stem and progenitor cells in lower vertebrates is particularly difficult due to the lack of suitable markers. In mammals, prominin-1 defines a broad range of embryonic and somatic stem and progenitor cells including those of the CNS. Recently, we have identified three distinct prominin molecules in axolotl. Remarkably, one of them (i.e. prominin-1) is upregulated upon tail amputation indicating a potential involvement of prominin–positive cells in spinal cord regeneration. Here we propose to dissect the physiological role of prominins in axolotl, and importantly to determine whether they can be used as cell surface markers for the isolation of rare postembryonic stem cells. To that end, we will perform first a detailed analysis of the general expression of these molecules both in the normal developing and adult animals with special emphasis on neurogenic matrix zones of the postembryonic axolotl. Second, their expression will be further documented in regenerating CNS. Third, we will address their functional aspect, for instance in spinal cord regeneration, by down regulating their expression by antisense-inhibition. Finally, we will investigate whether the neural progenitors in the regenerating spinal cord could be prospectively isolated based on the expression of prominin-1. Taken together, the proposed approach will offer a unique opportunity for prospective identification, characterization and eventual isolation of stem and progenitor cells in lower vertebrates.