Cellular interactions and gene activation during regeneration

Sergio Filoni Stefano Cannata

Professor of Compared Anatomy Researcher

Urodele amphibians are the only tetrapod vertebrates that have full regenerative capacity also as adults. In Anurans the regenerative power decreases during larval development and becomes very poor after metamorphosis. Thus, the causal analysis of the regenerative processes in anuran amphibians may provide a starting point to study the problem of regenerative failure during the evolution of vertebrates. Our research focuses on the regeneration of LIMB, LENS and CNS (central nervous system) in larval Xenopus laevis. LIMB: we demonstrated that the decrease in the regenerative power during the larval stage is not related to the decrease in innervation, as has been previously hypothesized since early limbs can regenerate even when denervated. We suggested that the formation of a nerve-independent blastema was due to the production, by early limb tissues, of mitogenic factors capable of imitating those delivered by nerves such as the Fibroblast Growth factors (FGFs). Present research: 1) identification of FGFs with polyclonal antibodies and RT-PCR from RNA of limb homogenates with primers specific for FGFs (XbFGF, XeFGF, FGF8); 2) analysis during regeneration of the expression of genes, such as sonic hedgehog (shh) and FGF8, expressed in developing limb: in situ hybridization. LENS: we demonstrated that the outer cornea of lentectomized eyes of larval X. laevis transdifferentiated into lens as the result of induction by the neural retina. Present research: 1) production of antibodies against the different crystallins to study the spatial and temporal pattern of crystalline synthesis during lens regeneration. 2) Analysis, by in situ hybridization, of expression pattern of genes such as Pax-6, Otx-2 and Sox-3, which are expressed during eye development. CNS: we demonstrated that the decrease in the regenerative power is related to the decrease of undifferentiated cell popupation in the ependymal layer. Present research: Analysis, during regeneration, of expression pattern of genes such as Pax-6, Otx-2, Otx-1, Krox-20, Engrailed which are involved in the regional development of the neuraxis. Effects of retinoic acid.