Recombinant Annexin A5 Alleviates Aluminum Chloride-Induced Cytotoxicity, Mitochondrial Dysfunction, and Apoptotic Signaling in SH-SY5Y Cells.

Abstract

Background: Aluminum contributes to neurodegeneration by inducing oxidative stress, disrupting mitochondrial membrane potential (MMP), and triggering apoptotic signaling cascades. Annexin A5 (ANXA5) is implicated in membrane repair, ion transport regulation, and neuroprotection. This study aimed to evaluate whether ANXA5 can mitigate aluminum-induced cytotoxicity in SH-SY5Y cells.

Methods: This in vitro study was conducted at Shiraz University of Medical Sciences, Shiraz, Iran, during 2023-2024. A recombinant ANXA5 was expressed in Escherichia coli and purified. The functional integrity of the purified ANXA5 was evaluated by assessing its ability to recognize apoptotic cells. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Rhodamine 123 staining, DNA fragmentation assay, and real-time polymerase chain reaction (real-time PCR) were used to assess the effects of aluminum chloride (AlCl₃) and ANXA5 on cell viability, MMP, DNA damage, and gene expression, respectively. Statistical analysis was conducted using SPSS software (version 16). One-way analysis of variance followed by Tukey's post-hoc test was employed for data analysis. Statistical significance was determined at P<0.05.

Results: Electrophoresis confirmed ANXA5 expression and purification. Purified ANXA5 successfully detected apoptotic cells, confirming the preservation of its functional activity after purification. AlCl₃ reduced the viability of SH-SY5Y cells in a dose-dependent manner (IC₅₀=450 µM). ANXA5 (1 µg/mL) reduced the cytotoxic effects of AlCl₃. In addition, ANXA5 (1 µg/mL) reduced the percentage of cells with low MMP, decreased DNA fragmentation, and Bax expression induced by AlCl₃ (P<0.001).

Conclusion: These findings demonstrated that ANXA5 provided significant protection against AlCl₃-induced cellular damage, including cytotoxicity, mitochondrial dysfunction, DNA fragmentation, and the expression of pro-apoptotic genes.