Extrinsic influences directing fate specification during development and regeneration

December 11th 2015
Versione stampabile

Venue: Edificio Povo 2, via Sommarive nr. 9, Povo (Tn) - Room B101
 At 4:00 p.m.

  • Patricia Regina Jusuf -  Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia

During retinal development and regeneration diverse subtypes of neurons are generated from multipotent progenitor cells in a distinct and highly conserved histogenic birthorder. This process depends on the co-ordinated and fluid changes in gene expression patterns within these progenitors. Additionally, feedback signals from the developing environment can contribute to ensure the generation of a fully functioning, robustly organized retina. Using the rapid development, transgenic tools and imaging capabilities of the zebrafish, we investigate which aspects of neurogenesis such extrinsic signals may influence. Genetic knockout techniques were used to generate zebrafish, in which distinct neural populations within the retina were missing. In the absence of these and their associated extrinsic signals, we find that the remaining retinal neurons still have the same birthdates, but that the expression of fate determinant factors of subsequent, but not earlier fates are delayed. During regeneration, we compared two different retinal injury models that ablate different populations of retinal neurons. In this setting, we show that regenerating progenitors are able to respond to these different environments and restore the ablated cell types preferentially. This suggests that extrinsic or environmental factors can and should be used to allow progenitors to regenerate the correctly balanced retinal architecture after injury. Together this work implies an important fine-tuning role for signals from different neuron types in the developing and regenerating retina that can direct progenitors towards specific cell fates to ensure that the final proportion of neural types and the correctly organized architecture of the retina is robustly generated.