Eye Absence Does Not Regulate Planarian Stem Cells during Eye Regeneration

Publication date: 27 February 2017
Source:Developmental Cell, Volume 40, Issue 4
Author(s): Samuel A. LoCascio, Sylvain W. Lapan, Peter W. Reddien
Dividing cells called neoblasts contain pluripotent stem cells and drive planarian flatworm regeneration from diverse injuries. A long-standing question is whether neoblasts directly sense and respond to the identity of missing tissues during regeneration. We used the eye to investigate this question. Surprisingly, eye removal was neither sufficient nor necessary for neoblasts to increase eye progenitor production. Neoblasts normally increase eye progenitor production following decapitation, facilitating regeneration. Eye removal alone, however, did not induce this response. Eye regeneration following eye-specific resection resulted from homeostatic rates of eye progenitor production and less cell death in the regenerating eye. Conversely, large head injuries that left eyes intact increased eye progenitor production. Large injuries also non-specifically increased progenitor production for multiple uninjured tissues. We propose a model for eye regeneration in which eye tissue production by planarian stem cells is not directly regulated by the absence of the eye itself.

Graphical abstract

Teaser

Whether planarian stem cells sense and respond to the absence of specific tissues during regeneration is unclear. LoCascio et al. provide evidence for a mechanism of tissue-specific eye regeneration that does not involve regulation of stem cells by the presence or absence of the eye itself.


http://ift.tt/2m8d0qi