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Updated: May 16, 2026
Intravitreous Injection for Establishing Ocular Diseases Model
Published on: October 1, 2007
Calcineurin activation causes retinal ganglion cell degeneration
Juan Qu1, Roland Matsouaka, Rebecca A Betensky
1Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
Purpose:
We previously reported that calcineurin, a Ca(2+)/calmodulin-dependent serine/threonine phosphatase, is activated and proposed that it participates in retinal ganglion cell (RGC) apoptosis in two rodent ocular hypertension models. In this study, we tested whether calcineurin activation by itself, even in the absence of ocular hypertension, is sufficient to cause RGC degeneration.
Methods:
We compared RGC and optic nerve morphology after adeno-associated virus serotype 2 (AAV2)-mediated transduction of RGCs with constitutively active calcineurin (CaNCA) or unactivated, wild-type calcineurin (CaNwt). Retinas and optic nerves were harvested 7-16 weeks after injection of the AAV into mouse vitreous. In flatmounted retinas, the transduced RGCs were identified with immunohistochemistry. The morphology of the RGCs was revealed by immunostaining for neurofilament SMI32 or by using GFP-M transgenic mice. A modified Sholl analysis was applied to analyze the RGC dendritic morphology. Optic nerve damage was assessed with optic nerve grading according to the Morrison standard.
Results:
CaNwt and CaNCA were highly expressed in the injected eyes. Compared to the CaNwt-expressing RGCs, the CaNCA-expressing RGCs had smaller somas, smaller dendritic field areas, shorter total dendrite lengths, and simpler dendritic branching patterns. At 16 weeks, the CaNCA-expressing eyes had greater optic nerve damage than the CaNwt-expressing eyes.
Conclusions:
Calcineurin activation is sufficient to cause RGC dendritic degeneration and optic nerve damage. These data support the hypothesis that calcineurin activation is an important mediator of RGC degeneration, and are consistent with the hypothesis that calcineurin activation may contribute to RGC neurodegeneration in glaucoma.
Insights
Calcineurin activation alone can cause retinal ganglion cell (RGC) degeneration and optic nerve damage, independent of ocular hypertension. This supports calcineurin
Area of Science:
- Neuroscience
- Ophthalmology
- Cell Biology
Background:
- Calcineurin, a phosphatase, is activated in rodent ocular hypertension models and implicated in retinal ganglion cell (RGC) apoptosis.
- Previous research suggested calcineurin's role in RGC apoptosis under hypertensive conditions.
Purpose of the Study:
- To determine if calcineurin activation alone, without ocular hypertension, is sufficient to induce RGC degeneration.
- To investigate the direct impact of calcineurin on RGC morphology and optic nerve integrity.
Main Methods:
- Adeno-associated virus serotype 2 (AAV2) mediated transduction of RGCs with active (CaNCA) or wild-type (CaNwt) calcineurin in mice.
- Assessment of RGC and optic nerve morphology 7-16 weeks post-injection using immunohistochemistry and optic nerve grading.
- Analysis of RGC dendritic morphology via modified Sholl analysis.
Main Results:
- High expression of both CaNwt and CaNCA in transduced eyes.
- CaNCA-expressing RGCs exhibited smaller somas, reduced dendritic field areas, and simpler dendritic structures compared to CaNwt.
- Significant optic nerve damage was observed in CaNCA-expressing eyes at 16 weeks.
Conclusions:
- Calcineurin activation is sufficient to induce RGC dendritic degeneration and optic nerve damage.
- These findings support calcineurin's role as a mediator of RGC degeneration.
- The results are consistent with calcineurin activation contributing to RGC neurodegeneration in glaucoma.
