Journal
PLOS BIOLOGY
Volume 4, Issue 9, Pages 1562-1571Publisher
PUBLIC LIBRARY SCIENCE
DOI: 10.1371/journal.pbio.0040272
Keywords
-
Categories
Funding
- Telethon [GGP04268] Funding Source: Medline
Ask authors/readers for more resources
The reason why different types of vertebrate nerve cells are generated in a particular sequence is still poorly understood. In the vertebrate retina, homeobox genes play a crucial role in establishing different cell identities. Here we provide evidence of a cellular clock that sequentially activates distinct homeobox genes in embryonic retinal cells, linking the identity of a retinal cell to its time of generation. By in situ expression analysis, we found that the three Xenopus homeobox genes Xotx5b, Xvsx1, and Xotx2 are initially transcribed but not translated in early retinal progenitors. Their translation requires cell cycle progression and is sequentially activated in photoreceptors (Xotx5b) and bipolar cells (Xvsx1 and Xotx2). Furthermore, by in vivo lipofection of sensors'' in which green fluorescent protein translation is under control of the 39 untranslated region (UTR), we found that the 39 UTRs of Xotx5b, Xvsx1, and Xotx2 are sufficient to drive a spatiotemporal pattern of translation matching that of the corresponding proteins and consistent with the time of generation of photoreceptors (Xotx5b) and bipolar cells (Xvsx1 and Xotx2). The block of cell cycle progression of single early retinal progenitors impairs their differentiation as photoreceptors and bipolar cells, but is rescued by the lipofection of Xotx5b and Xvsx1 coding sequences, respectively. This is the first evidence to our knowledge that vertebrate homeobox proteins can work as effectors of a cellular clock to establish distinct cell identities.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available