In silico investigation of valproic acid mediated GSK-3β inhibition and therapeutic mitigation of radiation induced intestinal injury.

Radiation-induced gastrointestinal injury is a dose-limiting complication of abdominal and pelvic radiotherapy, marked by epithelial loss, inflammation, and impaired regeneration. Glycogen synthase kinase-3β (GSK-3β), a negative regulator of canonical Wnt/β-catenin signaling, is central to intestinal stem cell maintenance and mucosal repair. Here, we evaluated valproic acid (VPA) as a modulator of GSK-3β using in silico docking and molecular dynamics, network biology, and in vivo irradiation models. Molecular docking analysis revealed favorable binding of VPA within the ATP-binding pocket of GSK-3β (binding free energy: -4.7 kcal/mol; estimated Ki: 0.36 mM). Notably, the predicted Ki falls within the clinically achievable therapeutic concentration range of VPA, supporting the potential for biologically relevant GSK-3β modulation in vivo. VPA interacted with residues implicated in ATP coordination, forming hydrogen bonds with Val139 and hydrophobic contacts with Gly67, Lys89, Asp137, and Tyr138. A 200-ns MD trajectory showed a stable VPA-GSK-3β complex and persistent hydrogen bonding, supporting electrostatic stabilization. MM/PBSA binding energies for VPA (-34.16 kcal/mol) were more favorable than the native ligand and known inhibitor (native: -35.09 kcal/mol, known inhibitor: -26.99 kcal/mol). Principal component analysis revealed ligand-dependent shifts in conformational sampling, suggesting altered active-site dynamics rather than full blockade. PPI network analysis connected GSK-3β modulation to stabilization of β-catenin and attenuation of NF-κB-driven inflammation. In vivo, VPA (100 mg/kg. b. wt) increased survival after whole-body irradiation (66% vs. 33%), restore gut permeability as well as jejunum crypt and villi length, and preserved colon length following abdominal irradiation. Together, these results support a model in which VPA exerts moderate, indirect inhibition of GSK-3β, nuclear translocation of β-catenin that favors Wnt-mediated regeneration, and reduces inflammatory responses in the irradiated intestine.