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Expression of ceruloplasmin in the retina: induction after optic nerve crush
1Department of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison 53792, USA.
Purpose:
To better understand the molecular program of neuronal cell death induced by axotomy, the authors attempted to identify retinal genes differentially expressed by optic nerve crush.
Methods:
Total RNA isolated from rat retinas at 1 and 4 days after intraorbital optic nerve crush was used in a modification of the differential display technique. After several rounds of screening, a single reproducibly upregulated band was reamplified and cloned, and differential expression was confirmed by Northern analysis.
Results:
Sequencing of the differentially expressed band revealed identity to the ferroxidase ceruloplasmin. Reverse transcription-polymerase chain reaction demonstrated high levels of ceruloplasmin expression in retina and liver, but minimal or no expression in brain, lung, spleen, kidney, or thymus of adult rats. The retina mRNA transcript was the same size as that of the liver, as measured by Northern blotting. In situ hybridization identified ceruloplasmin expression in the inner nuclear and ganglion cell layers of the retina, which increased after optic nerve crush. Immunoblotting confirmed expression of the same size protein product in the retina and the liver, and ceruloplasmin could be identified in the retina by immunofluorescence, which increased after optic nerve crush.
Conclusions:
Ceruloplasmin was expressed in the retina, and was induced by optic nerve crush. The possible role of ceruloplasmin in inhibiting reaction oxygen species in the retina after injury is discussed.
Insights
Optic nerve crush in rats induced ceruloplasmin expression in the retina. This study identified ceruloplasmin as a key gene involved in neuronal injury response after retinal damage.
Area of Science:
- Neuroscience
- Molecular Biology
- Ophthalmology
Background:
- Neuronal cell death following axotomy is a critical process in retinal injury.
- Understanding the molecular mechanisms of this cell death is essential for developing therapeutic strategies.
Purpose of the Study:
- To identify genes differentially expressed in the retina after optic nerve crush.
- To elucidate the molecular program underlying neuronal cell death induced by axotomy.
Main Methods:
- Differential display technique was employed using RNA from rat retinas post-optic nerve crush.
- Gene cloning, Northern analysis, reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, and immunoblotting were used for validation and characterization.
Main Results:
- Ceruloplasmin was identified as a significantly upregulated gene in the retina after optic nerve crush.
- Ceruloplasmin expression was confirmed in retinal cells (inner nuclear and ganglion cell layers) and increased post-injury.
- High ceruloplasmin expression was also noted in the liver, with minimal expression in other tested tissues.
Conclusions:
- Ceruloplasmin is expressed in the retina and its expression is induced by optic nerve crush.
- The findings suggest a potential role for ceruloplasmin in mitigating reactive oxygen species in the retina following injury.