Salidroside ameliorates diabetic amyotrophy by targeting Caspase-3 to inhibit apoptosis

Abstract

In this study, the Streptozotocin (STZ)-induced diabetes model in rats was employed to assess and verify the activity of salidroside (SAL) in ameliorating diabetic amyotrophy (DA). Network pharmacology analysis was used to obtain SDS-related targets, DA-related targets, and their intersectional targets. After subjecting the targets to GO enrichment and KEGG pathway analysis, a network "target pathway for SAL in ameliorating DA" was set up. Next, the Schrodinger Maestro 13.5 software was utilized for molecular docking to ascertain the binding free energy and binding mode between SAL and target proteins. Molecular dynamics simulations were performed using the Desmond program. Saturation mutation analysis was performed using Schrodinger's Maestro 13.5 software. SPR technology was used to explore the affinity between SAL and Caspase-3 protein. The expression level of Cleaved-Caspase-8, Caspase-8 p18, Cleaved-Caspase-3, Caspase-3 p17, PARP, and PARP P85 proteins in gastrocnemius tissue were determined by Western blotting (WB) analysis. In an STZ-induced rat diabetic model, SAL treatment significantly (P < 0.05) reduced blood glucose levels and increased forepaw force. HE and Masson staining results indicated that SAL treatment could significantly increase the mean muscle fiber area (P < 0.01) and decrease fibrosis (P < 0.05). Immunohistochemical results revealed that SAL treatment significantly increased (P < 0.01) the expression of Myogenin and decreased (P < 0.001) the expression of FBXO32 in gastrocnemius muscle tissue. Network pharmacological analysis identified that there were a total of 61 intersection proteins, among which TNF, APP, Caspase-3, PPARG, NQO1, HDAC1, BCL2, SRC, HDAC6, ACE, MAPK3, HSP90AA1, ATM, and REN emerged as potential core targets for SAL to ameliorate DA. Based on the crystal structure of the potential core protein, the complex structure model of the core target-SAL was created using molecular docking (XP mode of flexible docking), and the MMGBS analysis was carried out. The SPR results data demonstrated specific binding and kinetic compatibility between the SAL and Caspase-3 proteins. The results of WB revealed that compared with the model group, SAL significantly decreased (P < 0.05) expression of Cleaved Caspase-3, Caspase-3 p17, and PARP P85, and significantly increased (P < 0.05) the expression of PARP1, while the expression of Cleaved Caspase-8 and Caspase-8 p18 remained unchanged. These results suggest that Caspase-3 is a potential target for SAL to ameliorate DA which eventually plays a role in ameliorating DA by regulating apoptosis-related pathways, which provides a theoretical basis along with clues for the research and development of SAL as ameliorating DA drugs.

Keywords: Apoptosis; Caspase-3; Computational biology; Diabetic amyotrophy; Network pharmacology; Salidroside.

Fig. 1

Effects of salidroside on diabetic amyotrophy in STZ-induced diabetic rats. (A) Body weight. (B) Blood glucose. (C) Front paw force. (D) H&E staining of gastrocnemius muscle after 4 weeks of salidroside treatment. (E) Masson staining of gastrocnemius muscle after 4 weeks of salidroside treatment. (F and G) The expression of MyoG and FBXO32 proteins was detected by IHC, respectively, after 4 weeks of salidroside treatment.

Fig. 2

Network pharmacology predicts the target of salidroside relieving DA. (A) Venn diagram of potential targets of salidroside in ameliorating DA. (B and C) Salidroside ameliorates DA potential targets PPI network and Hithubs network. (D) The target that was enriched by the Gene Ontology of SAL in ameliorating DA. (E) The target was enriched by the KEGG Pathway of SAL in ameliorating DA. (F) SAL-target-pathway network model.

Fig. 3

Molecular docking predicts the binding activity of SAL to the target. Molecular docking complexes of SAL with Caspase-3 (A), NQO1 (B), REN (C), HDAC6 (D), ACE (E), HSP90AA1 (F), MAPK3 (G), PPARγ (H), BCL2 (I), SRC (J), TNF (K), APP (L) and HDAC1 (M) (Yellow represents hydrogen bonds, and green represents π-Cation bonds). (N) Statistical diagram of the MM/GBSA calculation for the complexes.

Fig. 4

MD simulation and saturation mutation of key binding sites predicted the binding sites of SAL and Caspase-3. (A) is the molecular dynamics simulation -RMSD value (The blue line represents the proteins, and the red line represents salidroside). (B) is the molecular dynamics simulation -RMSF value (α-helical and β-strand regions are highlighted in red and blue backgrounds, respectively. Protein residues that interact with the ligand are marked with green-colored vertical bars). (C) represents the contribution of amino acids at Caspase-3 binding sites to SAL-protein binding, respectively. (D) shows how interactions between SAL and specific amino acids of the Caspase-3 proteins have changed over time, respectively (shown in orange with varying depths, according to the proportions on the right side of the figure). € is a detailed diagram of SAL’s interactions with Caspase-3 protein residues. (F) Trend diagram of saturation mutagenesis results at key binding sites. (G) TOP10 results of saturation mutagenesis affinity of key binding sites.

Fig. 5

SAL targeting Caspase-3 inhibits the apoptosis pathway and alleviates DA. Surface plasmon resonance was used to test the affinity of Caspase-3 protein with different concentrations of salidroside (A) and Z-DEVD-FMK (B). (C) The expression of Cleaved-Caspase-8, Caspase-8 p18, Cleaved-Caspase-3, Caspase-3 p17, PARP, and PARP P85 proteins were detected by Western blot. Original blots are presented in Supplementary Fig. S3.