STAT3 Protein-Protein Interaction Analysis Finds P300 as a Regulator of STAT3 and Histone 3 Lysine 27 Acetylation in Pericytes

Background

Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic inducible transcription factor critical for mediating signals from cytokines, chemokines, and growth factors. Previous studies, including our own, have demonstrated that STAT3 directly regulates pro-fibrotic signaling in the kidney. The activation of STAT3′s transcriptional activity relies on specific protein-protein interactions, making it essential to identify and characterize these interactions to better understand their role in kidney disease. This study focuses on exploring protein-protein interactions involving STAT3 across three species to identify potential therapeutic targets for mitigating kidney disease.

Methods

We investigated protein-protein interactions linked to STAT3 activation or inhibition across humans (Homo sapiens), mice (Mus musculus), and rabbits (Oryctolagus cuniculus). Specifically, we examined the interaction between P300 and STAT3 by studying STAT3 activation via IL-6 stimulation and the effects of inhibiting P300 with its selective inhibitor, A-485, in pericytes. Immunoprecipitation assays were performed to confirm whether A-485 disrupts the binding of P300 to STAT3.

Results

Using the STRING application from ExPASy, we identified six proteins—PIAS3, JAK1, JAK2, EGFR, SRC, and EP300—that consistently exhibited high-confidence interactions with STAT3 across humans, mice, and rabbits. IL-6 treatment was shown to enhance STAT3 acetylation and increase histone 3 lysine 27 acetylation (H3K27ac). In contrast, the inhibition of P300 by A-485 disrupted the interaction between STAT3 and P300, reducing STAT3 acetylation and H3K27ac levels. Furthermore, A-485-mediated disruption of the STAT3-P300 interaction suppressed STAT3 transcriptional activity, as evidenced by decreased expression of Ccnd1 (Cyclin D1).

Conclusions

Disrupting the interaction between P300 and STAT3 represents a potential therapeutic strategy for alleviating STAT3-mediated fibrotic signaling in kidney disease across multiple species.