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, has the therapeutic effects on apoptosis, inflammation, and hypertrophy, etc. However, whether PDG has the protective role in diabetic cardiomyopathy (DCM) is not fully elucidated. This study aimed to investigate the role and its potential mechanism of PDG on 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. The changes of Ca^{2 +} fluorescence intensity values in H9c2 cells were evaluated by confocal microscopy. Apoptosis was evaluated by TUNEL staining and flow cytometer. The expressions of DCM-related genes and proteins both in vivo and in vitro were evaluated by qRT-PCR and Western blot. The results showed that PDG effectively improved the cardiac function and suppressed cardiac hypertrophy, inflammation, and cardiomyocytes apoptosis caused by DCM. Intriguingly, molecular docking results revealed that the therapeutic effect of PDG on DCM was associated to 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, and its associated store-operated calcium entry (SOCE). Therefore, our findings revealed that PDG can alleviate cardiac hypertrophy, inflammation and apoptosis on DCM by downregulating the STIM1, Orai1, and NFAT3 signaling molecules. Thus, PDG may be a promising therapeutic candidate for treating DCM.