PINK1 Protects against Staurosporine-Induced Apoptosis by Interacting with Beclin1 and Impairing Its Pro-Apoptotic Cleavage

Exogenous Hsp70 exerts neuroprotective effects in peripheral nerve rupture model

Hsp70 is the main molecular chaperone responsible for cellular proteostasis under normal conditions and for restoring the conformation or utilization of proteins damaged by stress. Increased expression of endogenous Hsp70 or administration of exogenous Hsp70 is known to exert neuroprotective effects in models of many neurodegenerative diseases. In this study, we have investigated the effect of exogenous Hsp70 on recovery from peripheral nerve injury in a model of sciatic nerve transection in rats. It was shown that recombinant Hsp70 after being added to the conduit connecting the ends of the nerve at the site of its extended severance, migrates along the nerve into the spinal ganglion and is retained there at least three days. In animals with the addition of recombinant Hsp70 to the conduit, a decrease in apoptosis in the spinal ganglion cells after nerve rupture, an increase in the level of PTEN-induced kinase 1 (PINK1), an increase in markers of nerve tissue regeneration and a decrease in functional deficit were observed compared to control animals. The obtained data indicate the possibility of using recombinant Hsp70 preparations to accelerate the recovery of patients after neurotrauma.

HMGB1 in the interplay between autophagy and apoptosis in cancer

Lysosome-mediated autophagy and caspase-dependent apoptosis are dynamic processes that maintain cellular homeostasis, ensuring cell health and functionality. The intricate interplay and reciprocal regulation between autophagy and apoptosis are implicated in various human diseases, including cancer. High-mobility group box 1 (HMGB1), a nonhistone chromosomal protein, plays a pivotal role in coordinating autophagy and apoptosis levels during tumor initiation, progression, and therapy. The regulation of autophagy machinery and the apoptosis pathway by HMGB1 is influenced by various factors, including the protein's subcellular localization, oxidative state, and interactions with binding partners. In this narrative review, we provide a comprehensive overview of the structure and function of HMGB1, with a specific focus on the interplay between autophagic degradation and apoptotic death in tumorigenesis and cancer therapy. Gaining a comprehensive understanding of the significance of HMGB1 as a biomarker and its potential as a therapeutic target in tumor diseases is crucial for advancing our knowledge of cell survival and cell death.

The natural chalcone cardamonin selectively induces apoptosis in human neuroblastoma cells

Neuroblastoma is the most common extracranial malignant tumor in childhood. Approximately 60% of all patients are classified as high-risk and require intensive treatment including non-selective chemotherapeutic agents leading to severe side effects. Recently, phytochemicals like the natural chalcone cardamonin (CD) have gained attention in cancer research. For the first time, we investigated the selective anti-cancer effects of CD in SH-SY5Y human neuroblastoma cells compared to healthy (normal) fibroblasts (NHDF). Our study revealed selective and dose-dependent cytotoxicity of CD in SH-SY5Y. The natural chalcone CD specifically altered the mitochondrial membrane potential (ΔΨm), as an early marker of apoptosis, in human neuroblastoma cells. Caspase activity was also selectively induced and the amount of cleaved caspase substrates such as PARP was thus increased in human neuroblastoma cells. CD-mediated apoptotic cell death was rescued by pan caspase inhibitor Z-VAD-FMK. The natural chalcone CD selectively induced apoptosis, the programmed cell death, in SH-SY5Y human neuroblastoma cells whereas NHDF being a model for normal (healthy) cells were unaffected. Our data indicates a clinical potential of CD in the more selective and less harmful treatment of neuroblastoma.

PINK1 regulates apoptosis of osteosarcoma as the target gene of cisplatin

BACKGROUND

Osteosarcoma is a common primary bone malignancy prevalent among adolescents and young adults. PTEN-induced kinase 1 (PINK1) regulates Parkinson's disease, but its role in cancers is unknown.

OBJECTIVE

This study was designed to analyze the mechanism by which PINK1 affects osteosarcoma using bioinformatics and cell experiments.

MATERIALS AND METHODS

The gene expression profiles were downloaded from the TARGET database. Several online databases were used to analyze the expression and protein‒protein interaction networks. CCK-8 cell viability assays and cisplatin treatment were used to assess cell activity with or without cisplatin treatment. Acridine orange/ethidium bromide (AO/EB) fluorescence staining was used to calculate the percentage of apoptotic cells.

RESULTS

Through bioinformatics analysis, we found that high expression of PINK1 was associated with poor prognosis in patients with osteosarcoma, and PINK1 inhibited apoptosis and promoted proliferation pathways. Next, we found that both PINK1 mRNA and protein levels were upregulated in osteosarcoma tissues. Additionally, we found that PTEN was reduced, while FOXO3a was markedly increased in osteosarcoma, suggesting that FOXO3a and not PTEN induced the overexpression of PINK1. CCK-8 and clonogenic assays showed that the knockdown of PINK1 decreased the growth of U2OS osteosarcoma cells. Ki67 immunofluorescence staining revealed that reduced cell proliferation in U2OS cells resulted in the depletion of PINK1. In addition, our AO/EB staining results indicated that the knockdown of PINK1 resulted in an increase in apoptotic cells and increased the levels of cleaved caspase-3. Furthermore, our experiments revealed that cisplatin promotes OS cell apoptosis by downregulating PINK1.

CONCLUSION

Collectively, our findings demonstrate that PINK1 is crucially involved in osteosarcoma and suggests that it can promote the apoptosis of OS cells as the downstream target gene of cisplatin.

The inhibition of PGAM5 suppresses seizures in a kainate-induced epilepsy model via mitophagy reduction

Background

Epilepsy is a common neurological disease, and excessive mitophagy is considered as one of the major triggers of epilepsy. Mitophagy is a crucial pathway affecting reactive oxygen species. Phosphoglycerate mutase 5 (PGAM5) is a protein phosphatase present in mitochondria that regulates many biological processes including mitophagy and cell death. However, the mechanism of PGAM5 in epilepsy remains unclear. The purpose of the present study was to examine whether PGAM5 affects epilepsy through PTEN-induced putative kinase 1 (PINK1)-mediated mitophagy.

Methods

After the knockdown of PGAM5 expression by the adeno-associated virus, an epilepsy model was created by kainic acid. Next, the seizure activity was recorded by local field potentials before evaluating the level of mitochondrial autophagy marker proteins. Lastly, the ultrastructure of mitochondria, neuronal damage and oxidative stress levels were further observed.

Results

A higher PGAM5 level was found in epilepsy, and its cellular localization was in neurons. The interactions between PGAM5 and PINK1 in epilepsy were further found. After the knockdown of PGAM5, the level of PINK1 and light chain 3B was decreased and the expression of the translocase of the inner mitochondrial membrane 23 and translocase of the outer mitochondrial membrane 20 were both increased. Knockdown of PGAM5 also resulted in reduced neuronal damage, decreased malondialdehyde levels, decreased reactive oxygen species production and increased superoxide dismutase activity. In addition, the duration of spontaneous seizure-like events (SLEs), the number of SLEs and the time spent in SLEs were all reduced in the epilepsy model after inhibition of PGAM5 expression.

Conclusion

Inhibition of PGAM5 expression reduces seizures via inhibiting PINK1-mediated mitophagy.

Counteractions of a Novel Hydroalcoholic Extract from Lens Culinaria against the Dexamethasone-Induced Osteoblast Loss of Native Murine Cells

The cytoprotective effects of a novel hydroalcoholic extract (0.01–5 mg/mL) from Lens culinaria (Terre di Altamura Srl) were investigated within murine native skeletal muscle fibers, bone marrow cells, and osteoblasts, and in cell lines treated with the apoptotic agent staurosporine (2.14 × 10⁻⁶ M), the alkylating drug cisplatin (10⁻⁴ M), the topoisomerase I inhibitor irinotecan (10⁻⁴ M), the antimitotic pro-oxidant doxorubicin (10⁻⁶ M), and the immunosuppressant dexamethasone (2 × 10⁻⁶ M). An amount of 10g of plant material was used to obtain a 70% ethanol/water product, following two-step extraction, evaporation, lyophilization, and storage at −20 °C. For the murine osteoblasts, doxorubicin reduced survival by −65%, dexamethasone by −32% and −60% after 24 and 48 h of incubation time, respectively. The extract was effective in preventing the osteoblast count-reduction induced by dexamethasone; it was also effective at preventing the inhibition of mineralization induced by dexamethasone. Doxorubicin and cisplatin caused a significant reduction in cell growth by −77% for bone marrow cells, −43% for irinotecan, and −60% for dexamethasone, but there was no evidence for the cytoprotective effects of the extract in these cells. Staurosporine and doxorubicin caused a fiber death rate of >−40% after 18 and 24 h of incubation, yet the extract was not effective at preventing these effects. The extract was effective in preventing the staurosporine-induced reduction of HEK293 proliferation and colony formation in the crystal violet DNA staining and the clonogenic assays. It was also effective for the cisplatin-induced reduction in HEK293 cell proliferation. The extract, however, failed to protect the SHSY5Y neurons against cisplatin and irinotecan-induced cytotoxicity. A UV/VIS spectroscopy analysis showed three peaks at the wavelengths of 350, 260, and 190 nm, which correspond to flavonoids, proanthocyanins, salicylates, and AA, constituting the extract. These data suggest the possible development of this extract for use against dexamethasone-induced bone loss and renal chemotherapy-induced damage.

Crosstalk of Autophagy and Apoptosis

Autophagy and apoptosis represent two fundamental pathophysiological mechanisms of cell fate regulation. However, the signaling pathways of these processes are significantly interconnected through various mechanisms of crosstalk. Indeed, autophagy/apoptosis crosstalk is still an emerging field, in which an increasing number of molecules are involved, including, for example, PINK1 and ERLINs. On the other hand, this crosstalk involves signal transduction pathways which are strongly dependent on Ca²⁺. Interestingly, crosstalk between autophagy and apoptosis impacts several pathologies, including multiple rheumatic diseases. The purpose of this Special Issue is also to investigate the bioactive properties of drugs with antitumor activity, focusing particularly on the role of anthraquinone derivatives in the regulation of cell death and autophagy crosstalk. This Special Issue of Cells brings together the most recent advances in understanding the various aspects of crosstalk between autophagy and apoptosis and the interconnected signaling pathways, implying therapeutic perspectives for the utility of its modulation in an anti-cancer setting.