UNC93B1 Mediates the Effects of cGAS-STING on ER Stress and Iron Death, and Reduces Renal Toxicity in Cadmium-Exposed Rats

BACKGROUND

Long-term exposure to cadmium can induce renal toxicity in rats, leading to endoplasmic reticulum (ER) stress and iron death. Notably, in cadmium-exposed rats, there is an increased expression of UNC93B1 (unc-93 homolog B1). Consequently, our investigation aims to determine the impact of UNC93B1 on ER stress and iron death in cadmium-exposed rats by modulating the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) pathway.

METHODS

A cadmium-exposed rat model was established by intrabacally injecting chromium chloride (5 mg/kg, once a day for 4 weeks), and the levels of UCd (urine cadmium), UNAG (urine N-acetyl-β-D-glucosaminidase), and UCr (urine creatinine) in urine were assessed. A silent UNC93B1 lentivirus was constructed, and STING agonists were procured and administered to the rats. Subsequently, kidney tissues were extracted post-mortem, and pathological changes in renal tissue were observed through hematoxylin and eosin (HE) staining. The expression and mRNA levels of UNC93B1, cGAS, and STING were examined using western blot (WB) and polymerase chain reaction (PCR). Autophagy proteins (light chain 3 (LC3), Beclin-1, p62) were also assessed by WB. Additionally, iron concentration was determined using a kit, while oxidative stress markers (cytochrome oxidase subunit 2 (COX2), glutathione peroxidase 4 (GPX4), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH)) were measured through enzyme-linked immunosorbent assay (ELISA). Furthermore, endoplasmic reticulum stress proteins (protein kinase RNA-like ER kinase (PERK), CCAAT enhance-binding protein homologous protein (CHOP), activating transcription factor-4 (ATF4)) were analyzed by WB.

RESULTS

Wstaining, WB, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), ELISA, and HE staining collectively revealed a heightened expression of UNC93B1, cGAS, and STING, accompanied by increased levels of autophagy, oxidative stress, and ER stress in cadmium-exposed rats (p < 0.05). Nephrotoxicity exhibited a reduction following the inhibition of UNC93B1, leading to decreased levels of oxidative stress, autophagy, and ER stress (p < 0.05). Notably, this observed phenomenon was reversed upon the addition of STING agonists, suggesting that UNC93B1 might exert a nephroprotective effect in cadmium-exposed rats through modulation of the cGAS-STING pathway.

CONCLUSIONS

The inhibition of UNC93B1 mitigates nephrotoxicity in cadmium-exposed rats, and this protective effect is mechanistically linked to the cGAS-STING pathway.

Mechanistic study of electroacupuncture preconditioning in alleviating myocardial ischemia-reperfusion injury in rats: involvement of mTOR/ROS signaling pathway to inhibit ferroptosis

PURPOSE

The objective of this study was to investigate the mechanism of electroacupuncture pretreatment in reducing myocardial ischemia-reperfusion injury in rats.

MATERIALS AND METHODS

The comparison of HR among the different groups did not yield statistically significant differences (p > 0.05). Additionally, the trend of HR change at different time points within each group was not statistically significant (p > 0.05). In contrast, the comparison of SBP among the different groups showed statistically significant differences (p < 0.05). Furthermore, the trend of SBP change at different time points within each group exhibited significant differences (p < 0.05).

RESULTS

Compared to the Sham group, rats in the I/R group and EA control group showed a significant decrease in EF, FS, SOD, p-mTOR/mTOR, GPX4, and FTH1, and an increase in CK-MB, cTnI, LDH, iron, ROS, MDA, ACSL4, and NCOA4 (p < 0.05). Compared to EA control group, rats in the EA group exhibited a significant increase in EF, FS, SOD, p-mTOR/mTOR, GPX4, and FTH1, and a decrease in CK-MB, cTnI, LDH, iron, ROS, MDA, ACSL4, and NCOA4 (p < 0.05). Compared to the EA group, rats in the EA + RAP group showed a significant decrease in EF, FS, SOD, p-mTOR/mTOR, GPX4, and FTH1, and an increase in CK-MB, cTnI, LDH, iron, ROS, MDA, ACSL4, and NCOA4 (p < 0.05).

CONCLUSIONS

Electroacupuncture preconditioning confers protective effects against myocardial ischemia-reperfusion injury in rats. Its mechanism may involve the activation of the mTOR/ROS signaling pathway by electroacupuncture to inhibit ferroptosis.

A Mechanism Study on the Antioxidant Pathway of Keap1-Nrf2-ARE Inhibiting Ferroptosis in Dopaminergic Neurons

BACKGROUND

The pathology of Parkinson's disease (PD) indicates that iron deposition exists in dopaminergic neurons, which may be related to the death of cellular lipid iron peroxide. The extracellular autophagy adaptor SQSTM1(p62) of dopamine (DA) neurons can activate the intracellular Keap1-Nrf2-ARE signaling pathway to inhibit ferroptosis, which has a protective effect on DA neurons.

OBJECTIVE

The objective of this study was to investigate the protective mechanism of the Keap1-Nrf2-ARE antioxidant pathway against iron death in dopaminergic neurons.

METHODS

The experiment was divided into a control group (Control group), 1-methyl-4-phenylpyridiniumion control group (MPP+ Control group), p62 overexpression group (MPP+OV-p62), and p62 overexpression no-load group (MPP+ OV-P62-NC). The inhibitors brusatol and ZnPP inhibited the activation of NF-E2-related factor 2(Nrf2) and Heme oxygenase-1(HO-1), respectively, and were divided into brusatol group (MPP+OV-p62+brusatol) and ZnPP group (MPP+OV-p62+ZnPP). RT-qPCR was used to detect transfection efficiency, and Cell Counting Kit-8 (CCK8) was used to detect cell activity. FerroOrange, 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA), and Liperfluo probes were used to detect intracellular iron, reactive oxygen species (ROS), and lipid peroxidation (LPO) levels. Western Blotting detected the levels of Nrf2, HO-1, Kelch-like ECH-associated protein1 (Keap1), and their downstream Glutathione peroxidase 4(GPX4) and Acyl-CoA synthetase long-chain family member 4(ACSL4). The levels of L-Glutathione (GSH) and Malondialdehyde (MDA) were detected by GSH and MDA kits, and the activation of Keap1-Nrf2-ARE pathway was verified at the cellular level to have an antioxidant protective effect on iron death in dopaminergic neurons.

RESULTS

(1) The results of RT-qPCR showed that compared with the control group, the expression of the p62 gene was significantly increased in the MPP+OV-p62 groups (p = 0.039), and the p62 gene was significantly increased in the brusatol and ZnPP groups, indicating successful transfection (p =0.002; p=0.008). (2) The immunofluorescence probe flow results showed that compared to the normal control group, the contents of three kinds of probes in MPP+ model group were significantly increased (p =0.001; p <0.001; p<0.001), and the contents of three kinds of probes in MPP+OV-p62 group were decreased compared to the MPP+ model group (p =0.004). The results indicated that the levels of iron, ROS, and LPO were increased in the MPP+ group and decreased in the MPP+OV-p62 group. (3) Compared with the control group, the expressions of Nrf2, HO-1, and GPX4 in the MPP+OV-p62 group were increased (p =0.007; p =0.004; p=0.010), and the expressions of Keap1 and ACSL4 in MPP+p62 overexpression group were decreased (p =0.017; p =0.005). Compared with the MPP+ control group, Nrf2 and GPX4 were increased in the MPP+OV-p62 group, and ACSL4 was decreased in the MPP+OV-p62 group (p =0.041; p <0.001; p <0.001). The results of the GSH and MDA kit showed that compared with the normal control group, the content of GSH in the MPP+ control group was decreased (p < 0.01), and the content of MDA was increased (p < 0.01). Compared with the MPP+ model group, GSH content was increased (P = 0.003), and MDA content was decreased in the MPP+OV-p62 group (p < 0.001). Nrf2, HO-1, and GPX4 increased in the MPP+p62 overexpression group but decreased in the brusatol group and ZnPP group (p < 0.001).

CONCLUSION

Based on the transfection of P62 plasmid, it was found that P62 plasmid can inhibit the lipid peroxidation of iron death in dopaminergic nerve cells by activating the Nrf2 signaling pathway, thus playing a protective role in dopaminergic nerve cells.

Identification of the potential ferroptosis key genes in lung cancer with bone metastasis

Background

To identify the potential key genes of ferroptosis in the pathogenesis of lung cancer with bone metastasis (LCBM) by bioinformatics analysis to provide new targets for treating LCBM and an indicator for early monitoring.

Methods

We first obtained differentially expressed genes (DEGs) associated with ferroptosis from the Gene Expression Omnibus (GEO) database. MiRWalk 2.0 was used to predict the key microRNAs (miRNAs) and construct related gene-miRNA interaction networks. The functional enrichment analysis of key miRNAs was performed using the miEAA database. Finally, the clinical data of 105 lung cancer patients were retrospectively analyzed, and logistic regression analysis was conducted to assess the relationship between serum alkaline phosphatase (ALP), neuron-specific enolase (NSE), and bone metastasis in lung cancer patients, and a receiver operating characteristic (ROC) curve was drawn.

Results

We identified 15 ferroptosis-related genes that were differentially expressed in lung cancer bone metastasis. GO and KEGG enrichment analyses suggested that these genes may affect the oxidative stress response, hypoxia response, rough endoplasmic reticulum, mitochondrial outer membrane, iron-sulfur cluster binding, virus receptor activity, central carbon metabolism in cancer, the interleukin-17 (IL-17) signaling pathway, and other aspects to participate in the occurrence and development of lung cancer bone metastasis. Among the 105 lung cancer patients included in the study, 39 cases had bone metastasis, and the incidence rate was 37.14%. A high Eastern Cooperative Oncology Group (ECOG) score and serum ALP and NSE overexpression were associated with bone metastasis in patients with lung cancer. By assessing the risk of bone metastasis in patients with lung cancer, we found that the Area Under Curves (AUCs) of serum ALP and NSE alone and combined were >0.70.

Conclusions

The differentially expressed ferroptosis-related genes and predicted miRNA regulatory network in lung cancer bone metastasis and the related functional enrichment analysis provide new targets for the treatment of lung cancer bone metastasis. At the same time, from a serological perspective, it was found that early monitoring of serum ALP and NSE expression in patients with lung cancer could be considered to assess the risk of bone metastasis in the future.

Research progress of glutathione peroxidase family (GPX) in redoxidation

Maintaining the balance of a cell's redox function is key to determining cell fate. In the critical redox system of mammalian cells, glutathione peroxidase (GPX) is the most prominent family of proteins with a multifaceted function that affects almost all cellular processes. A total of eight members of the GPX family are currently found, namely GPX1-GPX8. They have long been used as antioxidant enzymes to play an important role in combating oxidative stress and maintaining redox balance. However, each member of the GPX family has a different mechanism of action and site of action in maintaining redox balance. GPX1-4 and GPX6 use selenocysteine as the active center to catalyze the reduction of H₂O₂ or organic hydroperoxides to water or corresponding alcohols, thereby reducing their toxicity and maintaining redox balance. In addition to reducing H₂O₂ and small molecule hydroperoxides, GPX4 is also capable of reducing complex lipid compounds. It is the only enzyme in the GPX family that directly reduces and destroys lipid hydroperoxides. The active sites of GPX5 and GPX7-GPX8 do not contain selenium cysteine (Secys), but instead, have cysteine residues (Cys) as their active sites. GPX5 is mainly expressed in epididymal tissue and plays a role in protecting sperm from oxidative stress. Both enzymes, GPX7 and GPX8, are located in the endoplasmic reticulum and are necessary enzymes involved in the oxidative folding of endoplasmic reticulum proteins, and GPX8 also plays an important role in the regulation of Ca²⁺ in the endoplasmic reticulum. With an in-depth understanding of the role of the GPX family members in health and disease development, redox balance has become the functional core of GPX family, in order to further clarify the expression and regulatory mechanism of each member in the redox process, we reviewed GPX family members separately.

[Effect of iron death inhibitor on hypoxia/reoxygenation injury of cardiomyocytes and its mechanism]

OBJECTIVE

To investigate the effects of ferrostatin-1 (Fer-1) on cardiomyocyte hypoxia/reoxygenation injury and its mechanisms.

METHODS

The original generation of myocardial cells were extracted from 1～3 d newborn SD rats, which were randomly divided into normal control group (control), hypoxia reoxygenation (H/R) group and hypoxia reoxygenation + iron death inhibitors group (H/R + Fer-1). After 52 h of culture, cells in H/R group were added with 4 mmol/L Na₂S₂O₄ solution. After 1 h of hypoxia, cells were reoxygenated with DMEM medium containing 10% calf serum for 3 h.The H/R+ Fer-1 group was pretreated with Fer-1 (2 μmol/L) for 24 h and then subjected to hypoxia and reoxygenation. The release rate of lactate dehydrogenase (LDH) was measured by UV spectrophotometry, the cell survival rate was measured by CCK-8 method, SOD was measured by xanthine oxidase method, MDA was measured by chemical coloration, and the changes of mitochondrial membrane potential and reactive oxygen species (ROS) were observed by immunofluorescence. Western blot was used to detect the expressions of ACSL4 and GPX4.

RESULTS

Compared with the control group, the cell activity, SOD release and MMP level were decreased (P＜0.05), the levels of LDH, MDA and ROS were increased (P＜0.05), the protein expression of ACSL4 was increased (P＜0.05), and the protein expression of GPX4 was decreased (P＜0.05) in H/R group. Compared with the H/R group, the cell activity, SOD release and MMP level were increased (P＜0.05), the level of LDH, MDA and ROS were decreased (P＜0.05), the protein expression of ACSL4 was decreased (P＜0.05), and the protein expression of GPX4 was increased (P＜0.05) in H/R+Fer-1 group.

CONCLUSION

Fer-1 can inhibit the production of intracellular reactive oxygen species by regulating ACSL4 and GPX4, thereby alleviating the hypoxia and reoxygenation injury of primary cardiomyocytes caused by iron death.