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The Mfn1-βIIPKC Interaction Regulates Mitochondrial Dysfunction via Sirt3 Following Experimental Subarachnoid
Tao Chen1,2, Yue Wang2, Yu-Hai Wang3
1Department of Neurosurgery, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210000, Jiangsu, China.
Abstract:
Neuronal injury following subarachnoid hemorrhage (SAH) has been shown to be associated with mitochondrial dysfunction and oxidative stress. βIIPKC, a subtype of protein kinase C (PKC), accumulates on the mitochondrial outer membrane and phosphorylates mitofusin 1 (Mfn1) at serine 86. Here, we investigated the role of Mfn1-βIIPKC interaction in brain damage and neurological function in both in vivo and in vitro experimental SAH models. The expression of βIIPKC protein and the interaction of Mfn1-βIIPKC were found to be increased after OxyHb treatment in primary cultured cortical neurons and were also observed in the brain following SAH in rats. Treatment with the βIIPKC inhibitor βIIV5-3 or SAMβA, a peptide that selectively antagonizes Mfn1-βIIPKC association, significantly attenuated the OxyHb-induced neuronal injury and apoptosis. These protective effects were accompanied by inhibited mitochondrial dysfunction and preserved mitochondrial biogenesis. The results of western blot showed that βIIV5-3 or SAMβA markedly increased the expression of Sirt3 and enhanced the activities of its downstream mitochondrial antioxidant enzymes in OxyHb-treated neurons. Knockdown of Sirt3 via specific targeted small interfering RNA (siRNA) partially prevented the βIIV5-3- or SAMβA-induced protection and antioxidative effects. In addition, treatment with βIIV5-3 or SAMβA in vivo was found to obviously reduce brain edema, alleviate neuroinflammation, and preserve neurological function after experimental SAH in rats. In congruent with in vitro data, the protection induced by βIIV5-3 or SAMβA was reduced by Sirt3 knockdown in vivo. In summary, our present results showed that blocking Mfn1-βIIPKC interaction protects against brain damage and mitochondrial dysfunction via Sirt3 following experimental SAH.
Insights
Blocking the Mfn1-βIIPKC interaction protects against brain damage after subarachnoid hemorrhage (SAH). This pathway involves preserving mitochondrial function and relies on Sirt3, offering a novel therapeutic target for SAH.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Subarachnoid hemorrhage (SAH) causes neuronal injury linked to mitochondrial dysfunction and oxidative stress.
- Protein kinase C (PKC) subtype βIIPKC accumulates on mitochondria, phosphorylating mitofusin 1 (Mfn1).
Purpose of the Study:
- To investigate the role of the Mfn1-βIIPKC interaction in brain damage and neurological function following experimental SAH.
- To explore the therapeutic potential of targeting this interaction.
Main Methods:
- Utilized in vitro (OxyHb-treated neurons) and in vivo (rat SAH models) experimental SAH models.
- Administered βIIPKC inhibitor (βIIV5-3) or Mfn1-βIIPKC antagonist (SAMβA).
- Assessed neuronal injury, apoptosis, mitochondrial function, Sirt3 expression, and neurological outcomes; employed siRNA for Sirt3 knockdown.
Main Results:
- Increased βIIPKC expression and Mfn1-βIIPKC interaction observed in SAH models.
- βIIV5-3 and SAMβA treatments attenuated neuronal injury, apoptosis, and mitochondrial dysfunction, preserving mitochondrial biogenesis.
- These treatments upregulated Sirt3 and its antioxidant enzyme activity, with Sirt3 knockdown partially reversing protective effects.
- In vivo, treatments reduced brain edema, neuroinflammation, and improved neurological function, effects dependent on Sirt3.
Conclusions:
- Blocking the Mfn1-βIIPKC interaction confers protection against brain damage and mitochondrial dysfunction in experimental SAH.
- The protective mechanism involves Sirt3-mediated enhancement of mitochondrial antioxidant capacity.
- Targeting the Mfn1-βIIPKC interaction represents a promising therapeutic strategy for SAH.
