A vital role for myosin-9 in puromycin aminonucleoside-induced podocyte injury by affecting actin cytoskeleton

Quantitative proteome and lysine succinylome characterization of zinc chloride smoke-induced lung injury in mice

The inhalation of zinc chloride (ZnCl2) smoke is one of common resources of lung injury, potentially resulting in severe pulmonary complications and even mortality. The influence of ZnCl2 smoke on lysine succinylation (Ksucc) in the lungs remains uncertain. In this study, we used a ZnCl2 smoke inhalation mouse model to perform global proteomic and lysine succinylome analyses. A total of 6781 Ksucc sites were identified in the lungs, with injured lungs demonstrating a reduction to approximately 2000 Ksucc sites, and 91 proteins exhibiting at least five differences in the number of Ksucc sites. Quantitative analysis revealed variations in expression of 384 proteins and 749 Ksucc sites. The analysis of protein-protein interactions was conducted for proteins displaying differential expression and differentially expressed lysine succinylation. Notably, proteins with altered Ksucc exhibited increased connectivity compared with that in differentially expressed proteins. Beyond metabolic pathways, these highly connected proteins were also involved in lung injury-associated pathological reactions, including processes such as focal adhesion, adherens junction, and complement and coagulation cascades. Collectively, our findings contribute to the understanding of the molecular mechanisms underlaying ZnCl2 smoke-induced lung injury with a specific emphasis on lysine succinylation. These findings could pave the way for targeted interventions and therapeutic strategies to mitigate severe pulmonary complications and mortality associated with such injuries in humans.

Functional, proteomic and phenotypic in vitro studies evidence podocyte injury after chronic exposure to heparin

Unfractionated heparin (UFH) is a widely used anticoagulant that possess numerous properties including anti-inflammatory, anti-viral, anti-angiogenesis, and anti-metastatic effects. The effect of this drug was evaluated on the podocyte, an important actor of the glomerular filtration. Using a functional approach, we demonstrate that heparin treatment leads to a functional podocyte perturbation characterized by the increase of podocyte monolayer permeability. This effect is enhanced with time of exposure. Proteomic study reveals that heparin down regulate focal adhesion and cytoskeletal protein expressions as well as the synthesis of glomerular basement membrane components. This study clearly demonstrates that UFH may affect podocyte function by altering cytoskeleton organization, cell-cell contacts and cell attachment.

NudCL2 regulates cell migration by stabilizing both myosin-9 and LIS1 with Hsp90

Cell migration plays pivotal roles in many biological processes; however, its underlying mechanism remains unclear. Here, we find that NudC-like protein 2 (NudCL2), a cochaperone of heat shock protein 90 (Hsp90), modulates cell migration by stabilizing both myosin-9 and lissencephaly protein 1 (LIS1). Either knockdown or knockout of NudCL2 significantly increases single-cell migration, but has no significant effect on collective cell migration. Immunoprecipitation–mass spectrometry and western blotting analyses reveal that NudCL2 binds to myosin-9 in mammalian cells. Depletion of NudCL2 not only decreases myosin-9 protein levels, but also results in actin disorganization. Ectopic expression of myosin-9 efficiently reverses defects in actin disorganization and single-cell migration in cells depleted of NudCL2. Interestingly, knockdown of myosin-9 increases both single and collective cell migration. Depletion of LIS1, a NudCL2 client protein, suppresses both single and collective cell migration, which exhibits the opposite effect compared with myosin-9 depletion. Co-depletion of myosin-9 and LIS1 promotes single-cell migration, resembling the phenotype caused by NudCL2 depletion. Furthermore, inhibition of Hsp90 ATPase activity also reduces the Hsp90-interacting protein myosin-9 stability and increases single-cell migration. Forced expression of Hsp90 efficiently reverses myosin-9 protein instability and the defects induced by NudCL2 depletion, but not vice versa. Taken together, these data suggest that NudCL2 plays an important role in the precise regulation of cell migration by stabilizing both myosin-9 and LIS1 via Hsp90 pathway.

Puromycin aminonucleoside-induced podocyte injury is ameliorated by the Smad3 inhibitor SIS3

Smad3 signaling and transgelin expression are often activated during puromycin aminonucleoside (PAN)‐induced podocyte injury. Here, we investigated whether the Smad3 inhibitor SIS3 can ameliorate damage to injured podocytes. A model of PAN‐induced podocyte injury was constructed using the MPC5 cell line. The effects of SIS3 on the expression of the podocyte cytoskeletal proteins transgelin, p15^INK4B, phosphor‐smad3, phosphor‐JAK/stat3, the apoptotic marker cleaved caspase 3, and c‐myc were investigated using western blot. The distribution of F‐actin in PAN‐induced podocyte injury was observed under an immunofluorescence microscope. PAN‐induced podocyte injury altered the distribution of F‐actin and transgelin, and colocalization of these two proteins was observed. Transgelin expression and Smad3 phosphorylation were increased in the MPC5 cell line with prolonged PAN treatment. In addition, c‐myc expression, p15^INK4B, and JAK phosphorylation were all increased after treatment with PAN. Treatment with the Smad3 inhibitor SIS3 reversed these phenomena and protected against PAN‐induced podocyte injury. Moreover, stimulating podocytes directly with TGFβ‐1 also led to enhanced expression of transgelin or phosphor‐JAK/stat3, and this could be inhibited by SIS3. In conclusion, transgelin expression was induced through the Smad3 signaling pathway during PAN‐induced podocyte injury, and the resulting abnormal distribution of F‐actin and the enhanced expression of transgelin could be reversed by blockade of this pathway.

Excessive arachidonic acid induced actin bunching remodeling and podocyte injury via a PKA-c-Abl dependent pathway

Recent studies have shown that serum secretory phospholipase A2 group IB (sPLA2-IB) is associated with proteinuric kidney diseases and plays a pivotal role in podocyte injury via its natural receptor. Arachidonic acid (AA), as a major metabolite of sPLA2-IB, regulates the actin bungling remodeling and contributes to the podocyte injury. However, the underlying mechanism of AA in the regulation of podocyte actin remodeling and human podocyte injury is unclear. Here, we reported that AA induced F-actin cytoskeletal ring formation and promoted protein kinase A (PKA), nephrin and c-Abl phosphorylation. Moreover, AA promoted c-Abl translocation from the nucleus to the cytoplasm and increased the recruitment of c-Abl to p-nephrin by the interaction between them. H89 (PKA inhibitor) provided protection against AA-induced F-actin bunching remodeling, down-regulated nephrin phosphorylation, and suppressed the c-Abl translocation and activation. STI571 (c-Abl inhibitor) also improved the AA associated F-actin bunching remodeling. In addition, H89 and STI571 both alleviated apoptosis and adhesion damage of podocyte. These results indicate that an excess of AA treatment is detrimental to the podocyte actin cytoskeleton and promotes podocyte injury due to the activation of PKA-c-Abl signaling.

Leonurine ameliorates adriamycin-induced podocyte injury via suppression of oxidative stress

Leonurine, a major bioactive component from Herba Leonuri, shows therapeutic potential in several diseases, including diabetes, cardiovascular disease, bovine mastitis and depression. In kidney, it was reported that leonurine was performing a protective effect in both acute kidney injury and renal fibrosis mice models. The aim of this study is to investigate the effect of leonurine in podocyte injury. In the mice model of adriamycin (ADR) -induced nephropathy, the application of leonurine significantly prevented early kidney damage, macrophage infiltration and proteinuria. Meanwhile, leonurine suppressed ADR-induced podocyte injury and reactive oxygen species (ROS) production. Consistent to in vivo results, leonurine prevented ADR-induced podocyte injury and ROS production in cultured human podocytes. All these results suggested that leonurine might suppress ADR-induced podocyte injury via inhibiting oxidative stress. Leonurine might be a novel therapeutic drug for prevention of glomerular diseases.

Hyperoside alleviates adriamycin-induced podocyte injury via inhibiting mitochondrial fission

Podocyte injury underlies many forms of glomerular diseases. Our previous study showed that hyperoside, a naturally occurring flavonoid, could decrease albuminuria at the early stage of diabetic nephropathy by ameliorating renal damage and podocyte injury. However, its protective mechanism against podocyte injury is unknown. A previous study demonstrated that hyperoside might inhibit amyloid β-protein-induced neurotoxicity by suppressing mitochondrial dysfunction. Both mitochondrial dysfunction and its upstream determinant mitochondrial fission were closely related to podocyte injury. Thus, in the current study, we tested the effect of hyperoside on mitochondrial dysfunction and mitochondrial fission in adriamycin (ADR)-induced podocyte injury. In the mice model of ADR-induced nephropathy, hyperoside treatment inhibited ADR-induced albuminuria and podocyte injury. Meanwhile, hyperoside also blocked ADR-induced mitochondrial dysfunction and mitochondrial fission. Consistently, in cultured human podocytes, hyperoside suppressed ADR-induced podocyte injury, mitochondrial dysfunction and mitochondrial fission. All these results indicated that hyperoside might inhibit ADR-induced mitochondrial dysfunction and podocyte injury through suppressing mitochondrial fission both in vivo and in vitro. The underlying mechanisms which we revealed support the therapeutic effects of hyperoside for a broad range of glomerular diseases.

p53/Drp1-dependent mitochondrial fission mediates aldosterone-induced podocyte injury and mitochondrial dysfunction

Mitochondrial dysfunction is increasingly recognized as an important factor in glomerular diseases. Previous study has shown that mitochondrial fission contributed to mitochondrial dysfunction. However, the mechanism of mitochondrial fission on mitochondrial dysfunction in aldosterone-induced podocyte injury remains ambiguous. This study aimed to investigate the pathogenic effect of mitochondrial fission both in vivo and in vitro. In an animal model of aldosterone-induced nephropathy, inhibition of the mitochondrial fission protein dynamin-related protein 1 (Drp1) suppressed aldosterone-induced podocyte injury. In cultured podocytes, aldosterone dose dependently induced Drp1 expression. Knockdown of Drp1 inhibited aldosterone-induced mitochondrial fission, mitochondrial dysfunction, and podocyte apoptosis. Furthermore, aldosterone dose dependently induced p53 expression. Knockdown of p53 inhibited aldosterone-induced Drp1 expression, mitochondrial dysfunction, and podocyte apoptosis. These findings implicated that aldosterone induced mitochondrial dysfunction and podocyte injury mediated by p53/Drp1-dependent mitochondrial fission, which may provide opportunities for therapeutic intervention for podocyte injury.