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Updated: May 28, 2026
Transplantation of GFP-expressing Blastomeres for Live Imaging of Retinal and Brain Development in Chimeric Zebrafish Embryos
Published on: July 19, 2010
Ectopic proliferation contributes to retinal dysplasia in the juvenile zebrafish patched2 mutant eye
Jonathan Bibliowicz1, Jeffrey M Gross
1Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, Texas, USA.
Purpose:
Patched is a well-studied tumor suppressor and negative regulator of the Hedgehog (Hh) pathway. Earlier work in this laboratory has shown that embryonic zebrafish patched2 (ptc2) mutant retinas possess an expanded ciliary marginal zone (CMZ) and phenotypes similar to those in human patients with basal cell naevus syndrome (BCNS), a congenital disorder linked to mutations in the human PTCH gene. This study extends the analysis of retinal structure and homeostasis in ptc2-/- mutants to juvenile stages, to determine whether Patched 2 function is essential in the postembryonic eye.
Methods:
Histologic, immunohistochemical, and molecular analyses were used to characterize retinal defects in the 6-week-old juvenile ptc2-/- retina.
Results:
Juvenile ptc2-/- mutants exhibited peripheral retinal dysplasias that included the presence of ectopic neuronal clusters in the inner nuclear layer (INL) and regions of disrupted retinal lamination. Retinal dysplasias were locally associated with ectopic proliferation. BrdU/EdU labeling and immunohistochemistry assays demonstrated that a population of ectopically proliferating cells gave rise to the ectopic neuronal clusters in the INL of ptc2-/- mutants and that this contributed to retinal dysplasia in the mutant eye.
Conclusions:
These results demonstrate a direct link between overproliferation and retinal dysplasia in the ptc2-/- juvenile retina and establish ectopic proliferation as the likely cellular underpinning of retinal dysplasia in juvenile ptc2-/- mutants.
Insights
Patched 2 (ptc2) gene mutations in juvenile zebrafish cause retinal dysplasia due to ectopic cell proliferation. This study links overproliferation to retinal development defects in ptc2-/- mutants.
Area of Science:
- Developmental biology
- Ophthalmology
- Genetics
Background:
- Patched (PTC) proteins are tumor suppressors regulating the Hedgehog (Hh) pathway.
- Mutations in PTCH are linked to basal cell naevus syndrome (BCNS).
- Previous studies showed ptc2 mutant zebrafish retinas have an expanded ciliary marginal zone (CMZ).
Purpose of the Study:
- To investigate the role of Patched 2 (ptc2) in postembryonic retinal development.
- To analyze retinal structure and homeostasis in juvenile ptc2-/- mutants.
Main Methods:
- Histologic, immunohistochemical, and molecular analyses were performed.
- BrdU/EdU labeling and EdU incorporation assays were used.
- Retinal structure and cell proliferation were examined in 6-week-old ptc2-/- zebrafish.
Main Results:
- Juvenile ptc2-/- mutants displayed peripheral retinal dysplasias.
- Ectopic neuronal clusters were observed in the inner nuclear layer (INL).
- Ectopic proliferation was associated with retinal dysplasia and neuronal cluster formation.
Conclusions:
- A direct link exists between overproliferation and retinal dysplasia in the juvenile ptc2-/- retina.
- Ectopic proliferation underlies retinal dysplasia in juvenile ptc2-/- mutants.
- Patched 2 function is essential for maintaining retinal structure and homeostasis postembryonically.
