RESUMO
Amphibians such as Xenopus tropicalis exhibit a remarkable capacity for tissue regeneration after traumatic injury. Although transforming growth factor-ß (TGF-ß) receptor signaling is known to be essential for tissue regeneration in fish and amphibians, the role of TGF-ß ligands in this process is not well understood. Here, we show that inhibition of TGF-ß1 function prevents tail regeneration in Xenopus tropicalis tadpoles. We found that expression of tgfb1 is present before tail amputation and is sustained throughout the regeneration process. CRISPR-mediated knock-out (KO) of tgfb1 retards tail regeneration; the phenotype of tgfb1 KO tadpoles can be rescued by injection of tgfb1 mRNA. Cell proliferation, a critical event for the success of tissue regeneration, is downregulated in tgfb1 KO tadpoles. In addition, tgfb1 KO reduces the expression of phosphorylated Smad2/3 (pSmad2/3) which is important for TGF-ß signal-mediated cell proliferation. Collectively, our results show that TGF-ß1 regulates cell proliferation through the activation of Smad2/3. We therefore propose that TGF-ß1 plays a critical role in TGF-ß receptor-dependent tadpole tail regeneration in Xenopus.
