Signaling during lens regeneration

Abstract

The newt is one of the few organisms that is able to undergo lens regeneration as an adult. This review will examine the signaling pathways that are involved in this amazing phenomenon. In addition to outlining the current research involved in elucidating the key signaling molecules in lens regeneration, we will also highlight some of the similarities and differences between lens regeneration and development.

Figure 1

Outline of events and pathways likely to be involved in lens regeneration. Upon lens removal or injury, PECs must reenter the cell cycle and thrombin is suspected to play a role in this. Following proliferation, the PECs dedifferentiate and then redifferentiate. The BMP, Wnt, and FGF pathways play pivotal roles in lens development. BMP antagonists have been shown to upregulate TFs such as six3 in the newt during regeneration as well as induce lens regeneration. RA has been shown to inhibit BMP and Wnt signaling in other systems, but the mechanism through which it works in inducing (along with six3) newt lens regeneration is unclear. Question marks depict possible roles of RA for induction of lens regeneration.

Figure 2

A diagram showing several factors involved in lens development. Some of these factors have also been examined in lens regeneration and are depicted with red color in the pathway. This might suggest conservation of function even though the inductive signals might be different.