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BMP signaling mediates stem/progenitor cell-induced retina regeneration

Haynes, Tracy, Gutierrez, Christian, Aycinena, Juan-Carlos, Tsonis, Panagiotis A., Del Rio-Tsonis, Katia
Proceedings of the National Academy of Sciences of the United States of America 2007 v.104 no.51 pp. 20380-20385
apoptosis, bone morphogenetic proteins, chicks, humans, mitogen-activated protein kinase, retina, stem cells
We identified a mechanism whereby retina regeneration in the embryonic chick can be induced by the contribution of stem/progenitor cells. We show that bone morphogenetic protein (BMP) signaling is sufficient and necessary to induce retina regeneration and that its action can be divided into two phases. By 3 days after postretinectomy (d PR), the BMP pathway directs proliferation and regeneration through the activation of Smad (canonical BMP pathway) and the up-regulation of FGF signaling by the MAPK pathway. By 7d PR, it induces apoptosis by activating p38 (a noncanonical BMP pathway) and down-regulating FGF signaling (by both MAPK and AKT pathways). Apoptosis at this later stage can be prevented, and BMP-induced regeneration can be further induced by inhibition of p38. These results unravel a mechanism for stem/progenitor cell-mediated retina regeneration, where BMP activation establishes a cross-talk with the FGF pathway and selectively activates the canonical and noncanonical BMP pathways. Retina stem/progenitor cells exist in other species, including humans. Thus, our findings provide insights on how retinal stem cells can be activated for possible regenerative therapies.