Synergistic Utilization of Necrostatin-1 and Z-VAD-FMK Efficiently Promotes the Survival of Compression-Induced Nucleus Pulposus Cells via Alleviating Mitochondrial Dysfunction

SP1/CTR1-mediated oxidative stress-induced cuproptosis in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is an age-related disease and is responsible for low back pain. Oxidative stress-induced cell death plays a fundamental role in IDD pathogenesis. Cuproptosis is a recently discovered form of programmed cell death dependent on copper availability. Whether cuproptosis is involved in IDD progression remains unknown. Herein, we established in vitro and in vivo models to investigate cuproptosis in IDD and the mechanisms by which oxidative stress interacts with copper sensitivity in nucleus pulposus cells (NPCs). We found that ferredoxin-1 (FDX1) content increased in both rat and human degenerated discs. Sublethal oxidative stress on NPCs led to increased FDX1 expression, tricarboxylic acid (TCA) cycle-related proteins lipoylation and aggregation, and cell death in the presence of Cu2+ at physiological concentrations, while FDX1 knockdown inhibited cell death. Since copper homeostasis is involved in copper-induced cytotoxicity, we investigated the role of copper transport-related proteins, including importer (CTR1) and efflux pumps (ATPase transporter, ATP7A, and ATP7B). CTR1 and ATP7A content increased under oxidative stress, and blocking CTR1 reduced oxidative stress/copper-induced TCA-related protein aggregation and cell death. Moreover, oxidative stress promoted the expression of specific protein 1 (SP1) and SP1-mediated CTR1 transcription. SP1 inhibition decreased cell death rates, preserved disc hydration, and alleviated tissue degeneration. This suggests that oxidative stress upregulates FDX1 expression and copper flux through promoting SP1-mediated CTR1 transcription, leading to increased TCA cycle-related protein aggregation and cuproptosis. This study highlights the importance of cuproptosis in IDD progression and provides a promising therapeutic target for IDD treatment.

Zearalenone promotes porcine ESCs apoptosis by enhancing Drp1-mediated mitochondrial fragmentation and activating the JNK pathway

Zearalenone (ZEA) is widely present in food and feed, and pigs are susceptible to its effects. This study explored the underlying function of ZEA-induced apoptosis in porcine endometrial stromal cells (ESCs) through activation of the JNK signaling pathway and mitochondrial division. This study utilized ESCs to explore the impact of exposure to ZEA. A mitochondrial division inhibitor (Mdivi) was also included as a reference. The results indicated a gradual decrease in cell viability with increasing ZEA concentration. In addition, ZEA can modify the growth status of porcine ESCs, disrupt their ultrastructure, and lead to apoptosis of porcine ESCs via the mitochondrial division pathway and JNK signaling pathway. In summary, our study found the critical targets of ZEA infected with pig ESCs, which provided a conceptual foundation to prevent and control ZEA.

Role of Necroptosis in Intervertebral Disc Degeneration

Apoptosis has historically been considered the primary form of programmed cell death (PCD) and is responsible for regulating cellular processes during development, homeostasis, and disease. Conversely, necrosis was considered uncontrolled and unregulated. However, recent evidence has unveiled the significance of necroptosis, a regulated form of necrosis, as an important mechanism of PCD alongside apoptosis. The activation of necroptosis leads to cellular membrane disruption, inflammation, and vascularization. This process is crucial in various pathological conditions, including intervertebral disc degeneration (IVDD), neurodegeneration, inflammatory diseases, multiple cancers, and kidney injury. In recent years, extensive research efforts have shed light on the molecular regulation of the necroptotic pathway. Various stimuli trigger necroptosis, and its regulation involves the activation of specific proteins such as receptor-interacting protein kinase 1 (RIPK1), RIPK3, and the mixed lineage kinase domain-like (MLKL) pseudokinase. Understanding the intricate mechanisms governing necroptosis holds great promise for developing novel therapeutic interventions targeting necroptosis-associated IVDD. The objective of this review is to contribute to the growing body of scientific knowledge in this area by providing a comprehensive overview of necroptosis and its association with IVDD. Ultimately, these understandings will allow the development of innovative drugs that can modulate the necroptotic pathway, offering new therapeutic avenues for individuals suffering from necroptosis.

Inhibition of SLC7A11-GPX4 signal pathway is involved in aconitine-induced ferroptosis in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitum species, with a long history of traditional application, were applied to treat rheumatism, arthritis, stroke, and pain in Chinese medical practice. However, misuse of Aconitum species may induce central nervous toxic effects, such as numbness, vomiting, and even coma. Aconitine has been proved to be the main toxic component of Aconitum plants. Neurotoxicity is the main toxic effect of aconitine, while the underlying mechanism of aconitine remains unclear.

AIM OF THE STUDY

The purpose of the study is to explore the effects and molecular mechanism of ferroptosis caused by aconitine in vivo and in vitro.

MATERIALS AND METHODS

Six-dpf zebrafish larvae and SH-SY5Y cells were treated with different concentrations of aconitine for 24 h. Inhibitors treatment, e.g. pretreatment with Necrostain-1 (Nec-1) and Z-VZD-FMK for 12 h, or with Ferrostain-1 (Fer-1) for 4 h, were involved in the identification of aconitine-induced ferroptosis. Transient transfection experiment was conducted to explore the effects of SLC7A11 in the process of aconitine-induced ferroptosis. The effects of aconitine on morphological changes, lipid peroxidation, ferrous ion, and ferroptosis were detected by transmission electron microscope, flow cytometry, confocal microscopy, enzyme-linked immunosorbent assay and western blotting.

RESULTS

In SH-SY5Y cells, morphological changes including shrunken mitochondria, increased mitochondrial membranes density and ruptured mitochondrial membranes were captured in aconitine-treated group. The cell viability and GSH content dose-dependently declined, levels of lipid reactive oxygen species (ROS), malondialdehyde (MDA), and ferrous ion significantly increased after aconitine exposure for 24 h. Ferroptosis inhibitor Fer-1 pretreatment effectively increased cell viability, GSH content, and decreased levels of MDA and lipid peroxidation, suggesting that aconitine induced ferroptosis. In addition, the protein expression of SLC7A11 and GPX4 were improved after Fer-1 preincubation, which indicated that aconitine triggered ferroptosis via the inhibition of SLC7A11 and the inactivation of GPX4. Ferroptotic characteristics, including GSH depletion and lipid peroxidation accumulation, were alleviated via overexpression of SLC7A11 to increase protein expression of GPX4. In zebrafish experiment, GSH depletion, lipid peroxidation accumulation, iron overload, and the decreased protein expression of SLC7A11 and GPX4 were also induced in zebrafish larvae after aconitine exposure. Taken together, aconitine triggered ferroptotic cell death via inhibiting SLC7A11/GPX4 signal pathway in vivo and in vitro.

CONCLUSION

All results indicated that aconitine triggered ferroptosis of SH-SY5Y cells and zebrafish larvae nerve cells, which involved the inhibition of SLC7A11/GPX4 signal pathway mediated by lipid peroxidation damage and iron overload.

Role of Caspase Family in Intervertebral Disc Degeneration and Its Therapeutic Prospects

Intervertebral disc degeneration (IVDD) is a common musculoskeletal degenerative disease worldwide, of which the main clinical manifestation is low back pain (LBP); approximately, 80% of people suffer from it in their lifetime. Currently, the pathogenesis of IVDD is unclear, and modern treatments can only alleviate its symptoms but cannot inhibit or reverse its progression. However, in recent years, targeted therapy has led to new therapeutic strategies. Cysteine-containing aspartate proteolytic enzymes (caspases) are a family of proteases present in the cytoplasm. They are evolutionarily conserved and are involved in cell growth, differentiation, and apoptotic death of eukaryotic cells. In recent years, it has been confirmed to be involved in the pathogenesis of various diseases, mainly by regulating cell apoptosis and inflammatory response. With continuous research on the pathogenesis and pathological process of IVDD, an increasing number of studies have shown that caspases are closely related to the IVDD process, especially in the intervertebral disc (IVD) cell apoptosis and inflammatory response. Therefore, herein we study the role of caspases in IVDD with respect to the structure of caspases and the related signaling pathways involved. This would help explore the strategy of regulating the activity of the caspases involved and develop caspase inhibitors to prevent and treat IVDD. The aim of this review was to identify the caspases involved in IVDD which could be potential targets for the treatment of IVDD.

RIPK1 Coordinates Bone Marrow Mesenchymal Stem Cell Survival by Maintaining Mitochondrial Homeostasis via p53

Survival of mesenchymal stem cells in the bone marrow is essential for bone marrow microenvironment homeostasis, but the molecular mechanisms remain poorly understood. RIPK1 has emerged as a critical molecule of programmed cell death in tissue homeostasis. However, little is known about the regulation of RIPK1 on bone marrow mesenchymal stem cells (MSCs). Here, we have investigated for the first time the role of RIPK1 in bone marrow MSCs. We have found that RIPK1 knockdown suppressed proliferation, differentiation, and migration in bone marrow MSCs. Furthermore, RIPK1 knockdown resulted in the opening of mitochondrial permeability transition pore (mPTP) and mtDNA damage, leading to mitochondrial dysfunction, and consequently induced apoptosis and necroptosis in bone marrow MSCs. Moreover, we identified that the p53-PUMA axis pathway was involved in mitochondrial dysfunction in RIPK1-deficient bone marrow MSCs. Together, our findings highlighted that RIPK1 was indispensable for bone marrow MSC survival.

Deoxynivalenol Induces Caspase-8-Mediated Apoptosis through the Mitochondrial Pathway in Hippocampal Nerve Cells of Piglet

Deoxynivalenol (DON) is a common trichothecene mycotoxin found worldwide. DON has broad toxicity towards animals and humans. However, the mechanism of DON-induced neurotoxicity in vitro has not been fully understood. This study investigated the hypothesis that DON toxicity in neurons occurs via the mitochondrial apoptotic pathway. Using piglet hippocampal nerve cells (PHNCs), we evaluated the effects of different concentrations of DON on typical indicators of apoptosis. The obtained results demonstrated that DON treatment inhibited PHNC proliferation and led to morphological, biochemical, and transcriptional changes consistent with apoptosis, including decreased mitochondrial membrane potential, mitochondrial release of cytochrome C (CYCS) and apoptosis inducing factor (AIF), and increased abundance of active cleaved-caspase-9 and cleaved-caspase-3. Increasing concentrations of DON led to decreased B-cell lymphoma-2 (Bcl-2) expression and increased expression of BCL2-associated X (Bax) and B-cell lymphoma-2 homology 3 interacting domain death agonist (Bid), which in turn increased transcriptional activity of the transcription factors AIF and P53 (a tumor suppressor gene, promotes apoptosis). The addition of a caspase-8 inhibitor abrogated these effects. These results reveal that DON induces apoptosis in PHNCs via the mitochondrial apoptosis pathway, and caspase-8 is shown to play an important role during apoptosis regulation.