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Published on: December 22, 2014
Synaptogenesis and outer segment formation are perturbed in the neural retina of Crx mutant mice
Eric M Morrow1, Takahisa Furukawa, Elio Raviola
1Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, New Research Building, Room 360K, NRB, Room 360K, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA. EMORROW@PARTNERS.ORG
Background:
In Leber's congenital amaurosis (LCA), affected individuals are blind, or nearly so, from birth. This early onset suggests abnormal development of the neural retina. Mutations in genes that affect the development and/or function of photoreceptor cells have been found to be responsible in some families. These examples include mutations in the photoreceptor transcription factor, Crx.
Results:
A Crx mutant strain of mice was created to serve as a model for LCA and to provide more insight into Crx's function. In this study, an ultrastructural analysis of the developing retina in Crx mutant mice was performed. Outer segment morphogenesis was found to be blocked at the elongation stage, leading to a failure in production of the phototransduction apparatus. Further, Crx-/- photoreceptors demonstrated severely abnormal synaptic endings in the outer plexiform layer.
Conclusions:
This is the first report of a synaptogenesis defect in an animal model for LCA. These data confirm the essential role this gene plays in multiple aspects of photoreceptor development and extend our understanding of the basic pathology of LCA.
Insights
Leber congenital amaurosis (LCA) is a severe inherited eye disease. A Crx gene mutation in mice models LCA, revealing critical roles in photoreceptor development and synaptic formation.
Area of Science:
- Ophthalmology
- Genetics
- Developmental Biology
Background:
- Leber congenital amaurosis (LCA) causes early-onset blindness due to abnormal neural retina development.
- Mutations in genes crucial for photoreceptor development, such as Crx, are implicated in some LCA cases.
Purpose of the Study:
- To investigate the function of the Crx gene in photoreceptor development.
- To establish a Crx mutant mouse model for studying LCA pathology.
Main Methods:
- Ultrastructural analysis of the developing retina in Crx mutant mice.
- Examination of photoreceptor outer segment morphogenesis and synaptic structure.
Main Results:
- Outer segment morphogenesis was arrested at the elongation stage in Crx mutant mice.
- Phototransduction apparatus production failed, and photoreceptor synaptic endings were abnormal.
- A synaptogenesis defect was identified in the outer plexiform layer.
Conclusions:
- Crx plays an essential role in multiple facets of photoreceptor development.
- This study provides new insights into the pathology of LCA by identifying a synaptogenesis defect in a relevant animal model.
