Destabilization of TIP60-PXR complex by rifampicin impairs wound-induced cell migration.

Abstract

The Tat interactive protein 60 (TIP60)-pregnane and xenobiotic receptor (PXR) complex plays a pivotal role in regulating cell migration during wound healing, and disruption of this complex can impair this function. Because PXR is a ligand-activated transcription factor responsive to structurally diverse compounds, we investigated how different ligands can influence the structural and functional integrity of the TIP60-PXR complex. Using an integrated computational approach, we assessed how various PXR ligands affect complex stability and among them, rifampicin, an established PXR activator, emerged as a notable disruptor. Although most ligands exhibited comparable docking energies in both PXR alone and the TIP60-PXR complex, rifampicin showed a significantly higher binding energy when docked with the complex, suggesting destabilization. Molecular dynamics simulations revealed that rifampicin disrupts key interface residues, with significant root mean square deviation fluctuations and a failure to stabilize the complex. Molecular mechanics Poisson-Boltzmann surface area binding free energy calculations further confirmed rifampicin's destabilizing effect. To validate these findings in a cellular context, we conducted live-cell imaging and coimmunoprecipitation assays. Rifampicin treatment drastically reduced the intracellular colocalization and physical interaction between TIP60 and PXR, thereby significantly compromising their ability to support wound-induced cell migration. This was evident across multiple cell lines, correlating with PXR expression levels. Our findings establish a direct mechanistic link between ligand-induced structural changes in PXR and the functional impairment of the TIP60-PXR complex. This study provides a critical platform for understanding how small molecules modulate coregulator interactions and offers new insights for designing targeted therapeutics aimed at enhancing tissue repair. SIGNIFICANCE STATEMENT: This study identifies ligand-dependent disruption of the TIP60-pregnane and xenobiotic receptor (PXR) complex as a critical regulatory mechanism controlling wound-induced cell migration. By combining computational modeling with cellular validation, it reveals that rifampicin uniquely destabilizes the TIP60-PXR interaction despite being a known PXR activator. These findings uncover how small molecules can selectively modulate coregulator complexes, linking ligand-induced structural changes to impaired tissue repair. The work provides mechanistic insight with important implications for drug safety and regenerative therapeutic design.