Diosmetin Restores Endoplasmic Reticulum Homeostasis to Ameliorate Podocyte Injury in Diabetic Kidney Disease by Targeting DNAJC3

Abstract

Background Diabetic kidney disease (DKD) causes high mortality and imposes a substantial healthcare burden, representing a major global public health challenge. The natural flavonoid diosmetin (DIO) shows promising therapeutic effects in DKD; however, its molecular mechanisms remain unclear. This study is aimed at clarifying the specific mechanisms and molecular targets through which DIO exerts its effects in DKD. Methods We established an in vitro podocyte injury model using high glucose (HG) and palmitic acid (PA) to evaluate the effects of DIO on podocyte viability. We performed transcriptomic analysis to identify potential mechanisms underlying the protective effects of DIO on podocytes, and we validated key pathway‐related proteins by Western blot. We applied molecular docking, cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) to identify potential target proteins, and we further validated these targets using shRNA technology. Finally, we established a DKD mouse model by combining a high‐fat/high‐sugar diet with streptozotocin (STZ) administration to assess the therapeutic effects of DIO and its capacity to alleviate endoplasmic reticulum stress (ERS). Results DIO significantly attenuated HG/PA–induced podocyte injury and restored podocyte viability. Gene set enrichment analysis (GSEA) showed that the MISFOLDED_PROTEIN_BINDING pathway, which is closely associated with ERS regulation, was upregulated after DIO treatment. At the molecular level, DIO increased the expression of DNAJC3, a key regulator of endoplasmic reticulum homeostasis within this pathway, and reduced the levels of ERS‐related proteins, including GRP78, P‐eIF2α/eIF2α, ATF4, and CHOP. Molecular interaction analyses demonstrated that DIO has a strong binding affinity for DNAJC3, indicating a direct targeting effect. Knockdown of DNAJC3 markedly weakened the protective effects of DIO on podocytes. In vivo, DIO treatment significantly improved hyperglycemia, proteinuria, renal pathological injury, and oxidative stress in DKD mice. Notably, DIO also enhanced DNAJC3 expression and suppressed ERS in DKD mice. Conclusions This study clarifies the molecular basis of DIO‐mediated protection in DKD, particularly in podocytes, by identifying DNAJC3 as a potential target that DIO inhibits ERS, restores ER homeostasis, and alleviates podocyte injury.