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XB-ART-35373
Dev Biol April 15, 2007; 304 (2): 675-86.

Transgenic Xenopus with prx1 limb enhancer reveals crucial contribution of MEK/ERK and PI3K/AKT pathways in blastema formation during limb regeneration.



Abstract
Understanding the mechanisms that control amphibian limb regeneration should allow us to decipher the critical differences between amphibians and humans, which have the limited ability of organ regeneration. However, many issues at the cellular and molecular levels still remain unresolved. We have generated a transgenic Xenopus laevis line that expresses green fluorescent protein (GFP) under the control of mouse prx1 limb enhancer, which directs reporter gene expression in limb mesenchyme in mice, and found that GFP accumulated in blastemal mesenchymal cells of the transgenic froglets after limb amputation. Thus, this transgenic line should provide a new approach to gain insights into the cellular dynamics and signaling pathways involved in limb blastema formation. We have also developed a culture system for forelimb explants of froglets and found that treatment with inhibitors of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) kinase 1/2 (MEK1/2) and phosphatidylinositol 3-kinase (PI3K) repressed GFP expression. These effects were partially reversible, and down-regulation of GFP was associated with inhibition of cell-cycle progression and induction of ectopic apoptosis. In addition, we found that ERK1/2 and AKT, downstream mediators of MEK1/2 and PI3K pathways, were activated in amputated forelimb stumps. These results demonstrate that MEK/ERK and PI3K/AKT pathways regulate limb blastema formation in the X. laevis froglet.

PubMed ID: 17303106
Article link: Dev Biol

Genes referenced: prrx1 myh1 msx1 mapk1 akt1 casp3 map2k1 pik3ca pik3cb pik3cg
Antibodies: Akt1 Ab5 BrdU Ab7 Casp3 Ab6 GFP Ab12 H3f3a Ab9 Mapk1 Ab3 Msx1/2 Ab1 Myh1 Ab1


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