An investigation into dedifferentiation stage-specific gene profiling, and a detailed examination of the expression of NvElastaseI and NvSLPI during limb regeneration in Notophthalmus viridescens

The red spotted newt has the uncommon ability to fully regenerate many complex and diverse structures in response to amputation or severe injury. Consistent between the epimorphic regeneration of each structure is the requirement of tissues to undergo the process of dedifferentiation. This is a poorly understood process. Because of the heterogeneity of the regeneration process and limitations inherent in the newt as a model organism, a molecular characterization of dedifferentiation has not previously been performed. In order to improve the characterization of the dedifferentiation process, a subtractive hybridization strategy was employed to isolate 59 candidate cDNAs involved in the dedifferentiation stage from newt limb regenerates. Further analysis of 10 of them suggested that 5 of them were specifically expressed or upregulated during the dedifferentiation stage. One clone, NvElastaseI, was further examined for its temporal and spatial correlation to the dedifferentiation process. The same analyses were performed on a candidate inhibitor of Elastase I--- NvSLPI. NvElastaseI demonstrated an expression pattern that suggested it may be involved in the dedifferentiation of intact tissues at the wound margin during the early stages of regeneration. In addition, based on the expression data and published accounts in other model systems, NvElastaseI, NvSLPI, and other clones identified by the screen may also contribute to the process of epithelial moulting. These results suggest that extracellular matrix remodeling and serine protease activity may be involved in the dedifferentiation stage and process, as well as suggest that newt moulting may represent a novel system within which to study the human psoriatic skin condition.