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Role of CAST-Drp1 Pathway in Retinal Neuron-Regulated Necrosis in Experimental Glaucoma
Su-Mei Liu1,2,3, Lv-Shuang Liao3,4, Ju-Fang Huang3
1Department of Anesthesiology, The Second Xiangya Hospital of Central South University, Changsha, 410011, China.
Objective:
Numerous studies have indicated that excitatory amino acid toxicity, such as glutamate toxicity, is involved in glaucoma. In addition, excessive glutamate can lead to an intracellular calcium overload, resulting in regulated necrosis. Our previous studies have found that the calpastatin (CAST)-calpain pathway plays an important role in retinal neuron-regulated necrosis after glutamate injury. Although inhibition of the calpain pathway can decrease regulated necrosis, necrotic cells remain. It has been suggested that there are other molecules that participate in retinal neuron-regulated necrosis. CAST is an important regulator of dynamin-related protein 1 (Drp1)-mediated mitochondrial defects. Thus, the aim of this study was to determine whether the CAST-Drp1 pathway may be an underlying signaling axis in neuron-regulated necrosis.
Methods:
Using cultured retinal neurons and in an in-vivo glaucoma model induced by glutamate overload, members of the CAST-Drp1 pathway were assessed by immunofluorescence, Western blotting, Phos-tagTM SDS-PAGE, and co-immunoprecipitation assays. Moreover, the black and white box test was performed on the rats.
Results:
We found that more retinal neuron-regulated necrosis and Drp1 activation as well as lower CAST levels were present in the glutamate-induced glaucoma model. Rats with glutamate-induced glaucoma exhibited impaired visual function. We also observed retinal neuron-regulated necrosis and Drp1 activity decreased, and impaired vision recovered after CAST active peptide application, indicating that the CAST-Drp1 pathway plays a critical role in retinal neuron-regulated necrosis and visual function.
Conclusion:
The results of this study indicate that the CAST-Drp1 pathway protects against retinal neuron-regulated necrosis, which may expand the therapeutic targets for the treatment of neurodegenerative disorders involving dysfunction of glutamate metabolism, such as glaucoma.
Insights
The calpastatin (CAST)-dynamin-related protein 1 (Drp1) pathway protects retinal neurons from glutamate-induced regulated necrosis and vision loss in glaucoma. Activating this pathway offers a potential therapeutic strategy for neurodegenerative diseases.
Area of Science:
- Neuroscience
- Ophthalmology
- Cell Biology
Background:
- Glutamate toxicity contributes to glaucoma and retinal neuron death via calcium overload and regulated necrosis.
- The calpastatin (CAST)-calpain pathway is implicated in this process, but other molecules may also be involved.
- CAST regulates dynamin-related protein 1 (Drp1)-mediated mitochondrial dysfunction.
Purpose of the Study:
- To investigate the role of the CAST-Drp1 pathway in retinal neuron-regulated necrosis.
- To determine if the CAST-Drp1 pathway is a key signaling axis in neuroprotection against glutamate injury.
Main Methods:
- Cultured retinal neurons and a glutamate-induced glaucoma rat model were used.
- Immunofluorescence, Western blotting, Phos-tag SDS-PAGE, and co-immunoprecipitation assessed CAST-Drp1 pathway members.
- Visual function was evaluated using the black and white box test.
Main Results:
- Glutamate-induced glaucoma models showed increased retinal neuron necrosis and Drp1 activation, with decreased CAST levels.
- Impaired visual function was observed in these rats.
- CAST active peptide application reduced necrosis and Drp1 activity, restoring visual function.
Conclusions:
- The CAST-Drp1 pathway is crucial for protecting retinal neurons against regulated necrosis.
- This pathway plays a significant role in maintaining visual function.
- The CAST-Drp1 pathway represents a potential therapeutic target for glaucoma and other neurodegenerative disorders involving glutamate metabolism dysfunction.
