Pinoresinol diglucoside from Eucommia ulmoides attenuates diabetic cardiomyopathy through suppressing the store-operated calcium entry and downregulating the STIM1/Orai1/NFAT3 signaling pathway

Pinoresinol diglucoside (PDG), an active component derived from Eucommia ulmoides, exhibits therapeutic effects against apoptosis, inflammation, and hypertrophy, etc. However, whether PDG plays a protective role in diabetic cardiomyopathy (DCM) is not fully elucidated. This study aimed to investigate the role and potential mechanism of PDG in DCM. The possible mechanism of PDG targeting DCM was identified by network pharmacology, bioinformatics, machine learning and molecular docking methods. The heart function of mice was evaluated using echocardiography. The pathological changes in the heart of mice were detected using H&E staining. Changes of Ca²⁺ fluorescence intensity values in H9c2 cells were assessed by confocal microscopy. Apoptosis was evaluated by TUNEL staining and flow cytometry. The expression of DCM-related genes and proteins, both in vivo and in vitro, was examined by qRT-PCR and Western blot. The results showed that PDG effectively improved the cardiac function and suppressed cardiac hypertrophy, inflammation, and cardiomyocyte apoptosis caused by DCM. Intriguingly, molecular docking results revealed that the therapeutic effect of PDG on DCM was associated with stromal interaction molecule 1 (STIM1), calcium release-activated calcium channel protein 1 (Orai1), and nuclear factor of activated T-cells 3 (NFAT3) signaling. Consistently, animal experiments results indicated that PDG significantly downregulated the expression of STIM1, Orai1, NFAT3 at the protein level, as well as the associated store-operated calcium entry (SOCE). Therefore, our findings revealed that PDG can alleviate cardiac hypertrophy, inflammation and apoptosis in DCM by downregulating the STIM1, Orai1, and NFAT3 signaling molecules. Thus, PDG may be a promising therapeutic candidate for treating DCM.