BCL2L13 promotes mitophagy through DNM1L-mediated mitochondrial fission in glioblastoma

Deciphering glioblastoma pathogenesis: Insights from mitophagy dysregulation and SNX7 as a therapeutic target

BACKGROUND

Glioblastoma is a highly aggressive and invasive brain tumor with an extremely poor prognosis. The aims of the present study are to investigate the pathogenesis of glioblastoma and identify potential therapeutic targets.

METHODS

We performed a systematic analysis of gene expression data from multiple datasets, including GEO and TCGA, to identify hub genes and pathways associated with glioblastoma progression. Bioinformatics tools were utilized to analyze differential gene expression, pathway enrichment and survival prognosis. Both in vitro and in vivo functional experiments were conducted to validate biological roles of SNX7.

RESULTS

Pathway analysis revealed significant enrichment of the mitophagy pathway in glioblastoma, indicating its critical role in tumor development. We identified 12 hub genes associated with glioblastoma prognosis, with high-risk patients having worse survival outcomes. Among the hub gene set, sorting nexin 7 (SNX7) was found to be the most significant regulator of glioblastoma progression. Our results also demonstrated that SNX7 expression is associated with tumor ferroptosis and genomic variations, representing potential biomarkers for clinical diagnosis and treatment. Furthermore, functional experiments confirmed that SNX7 promotes glioblastoma cell proliferation, invasion and survival by inhibiting protective mitophagy.

CONCLUSION

Our results highlight the importance of mitophagy dysregulation in the pathogenesis of glioblastoma and identify SNX7 as a novel therapeutic target. Further research is needed to elucidate the underlying mechanisms of SNX7 in glioblastoma and validate its clinical significance. These findings may facilitate the development of personalized treatment strategies and improve outcomes for glioblastoma patients.

AMPK regulates Bcl2-L-13-mediated mitophagy induction for cardioprotection

The accumulation of damaged mitochondria in the heart is associated with heart failure. Mitophagy is an autophagic degradation system that specifically targets damaged mitochondria. We have reported previously that Bcl2-like protein 13 (Bcl2-L-13) mediates mitophagy and mitochondrial fission in mammalian cells. However, the in vivo function of Bcl2-L-13 remains unclear. Here, we demonstrate that Bcl2-L-13-deficient mice and knockin mice, in which the phosphorylation site (Ser272) on Bcl2-L-13 was changed to Ala, showed left ventricular dysfunction in response to pressure overload. Attenuation of mitochondrial fission and mitophagy led to impairment of ATP production in these mouse hearts. In addition, we identified AMPKα2 as the kinase responsible for the phosphorylation of Bcl2-L-13 at Ser272. These results indicate that Bcl2-L-13 and its phosphorylation play an important role in maintaining cardiac function. Furthermore, the amplitude of stress-stimulated mitophagic activity could be modulated by AMPKα2.

o8G-miR-6513-5p/BCL2L13 Axis Regulates Mitophagy during Oxidative Stress in the Human Saphenous Vein Endothelial Cells

Venous graft decay (VGD) occurs in coronary artery bypass grafting (CABG), and ischemia-reperfusion oxidative stress injury during the operation is involved in VGD. To explore the cellular phenotypic changes during this process, a stable oxidative stress model of human saphenous vein endothelial cells (HSVECs) is constructed. Through proteomics and cell experiments, it is found that the expression of BCL2L13 is upregulated during oxidative stress of HSVECs, and BCL2L13 regulated mitophagy through receptor-mediated interaction with LC3 and plays a role in cell protection. During oxidative stress, intracellular o8G epigenetic modification occurs, and the o8G modification of miR-6513-5p causes this molecule to lose its targeted regulation of BCL2L13 and participates in the upregulation of BCL2L13. There is a regulatory pathway of o8G modification-BCL2L13-LC3-mitophagy when oxidative stress occurs in HSVECs.

Sex and Region-Specific Disruption of Autophagy and Mitophagy in Alzheimer's Disease: Linking Cellular Dysfunction to Cognitive Decline

Macroautophagy and mitophagy are critical processes in Alzheimer's disease (AD), yet their links to behavioral outcomes, particularly sex-specific differences, are not fully understood. This study investigates autophagy (LC3B-II, SQSTM1) and mitophagy (BNIP3L, BNIP3, BCL2L13) markers in the cortex and hippocampus of male and female 3xTg-AD mice, using western blotting, transmission electron microscopy (TEM), and behavioral tests (novel object recognition and novel object placement). Significant sex-specific differences emerged: female 3xTg-AD mice exhibited autophagosome accumulation due to impaired degradation in the cortex, while males showed fewer autophagosomes, especially in the hippocampus, without significant degradation changes. TEM analyses demonstrated variations in mitochondrial and mitophagosome numbers correlated with memory outcomes. Females had enhanced mitophagy, with higher BNIP3L and BCL2L13 levels, whereas males showed elevated BNIP3 dimers. Cognitive deficits in females correlated with mitochondrial dysfunction in the cortex, while in males, higher LC3B-II levels associated positively with cognitive performance, suggesting protective autophagy effects. Using machine learning, we predicted mitophagosome and mitochondrial numbers based on behavioral data, pioneering a predictive approach to cellular outcomes in AD. These findings underscore the importance of sex-specific regulation of autophagy and mitophagy in AD and support personalized therapeutic approaches targeting these pathways. Integrating machine learning emphasizes its potential to advance neurodegenerative research.

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BCL2L13 Influences Autophagy and Ceramide Metabolism without Affecting Temozolomide Resistance in Glioblastoma

Temozolomide (TMZ) resistance in glioblastoma (GB) poses a significant therapeutic challenge. We developed a TMZ-resistant (TMZ-R) U251 GB model, revealing distinct differences in cell viability, apoptosis, autophagy, and lipid metabolism between TMZ-R and non-resistant (TMZ-NR) cells. TMZ-NR cells exhibited heightened sensitivity to TMZ-induced apoptosis, while TMZ-R cells-maintained viability. Autophagy flux was completely inhibited in TMZ-R cells, indicated by LC3βII and SQSTM1 accumulation. BCL2L13, which showed higher expression in TMZ-R cells, demonstrated increased interaction with Ceramide Synthase 6 (CerS6) and reduced interaction with Ceramide Synthase 2 (CerS2) in TMZ-NR cells. BCL2L13 knockdown (KD) disrupted autophagy flux, decreasing autophagosome accumulation in TMZ-R cells while increasing it in TMZ-NR cells. These changes contributed to altered ceramide profiles, where TMZ-R cells displayed elevated levels of Cer 16:0, 18:0, 20:0, 22:0, 24:0, and 24:1. Our findings highlight BCL2L13 and altered ceramide metabolism as potential therapeutic targets to overcome TMZ resistance in GB.

Iron chelators as mitophagy agents: Potential and limitations

Mitochondrial autophagy (mitophagy) is very important process for the maintenance of cellular homeostasis, functionality and survival. Its dysregulation is associated with high risk and progression numerous serious diseases (e.g., oncological, neurodegenerative and cardiovascular ones). Therefore, targeting mitophagy mechanisms is very hot topic in the biological and medicinal research. The interrelationships between the regulation of mitophagy and iron homeostasis are now becoming apparent. In short, mitochondria are central point for the regulation of iron homeostasis, but change in intracellular cheatable iron level can induce/repress mitophagy. In this review, relationships between iron homeostasis and mitophagy are thoroughly discussed and described. Also, therapeutic applicability of mitophagy chelators in the context of individual diseases is comprehensively and critically evaluated.

Three-dimensional cultured human umbilical cord mesenchymal stem cells attenuate pulmonary fibrosis by improving the balance of mitochondrial fusion and fission

Pulmonary fibrosis is a kind of fibrotic interstitial pneumonia with poor prognosis. Aging, environmental pollution, and coronavirus disease 2019 are considered as independent risk factors for pulmonary fibrogenesis. Consequently, the morbidity and mortality striking continues to rise in recent years. However, the clinical therapeutic efficacy is very limited and unsatisfactory. So it is necessary to develop a new effective therapeutic approach for pulmonary fibrosis. Human umbilical cord mesenchymal stem cells (hucMSCs) are considered as a promising treatment for various diseases because of their multiple differentiation and immunomodulatory function. The key bottleneck in the clinical application of hucMSCs therapy is the high-quality and large-scale production. This study used FloTrix miniSpin bioreactor, a three-dimensional (3D) cell culture system, for large-scale expansion of hucMSCs in vitro, and proved 3D cultured hucMSCs inhibited the differentiation of fibroblasts into myofibroblasts and myofibroblasts proliferation and migration, leading to slow down the development of pulmonary fibrosis. Further mechanistic studies clarified that hucMSCs reduced the amount of binding between circELP2 and miR-630, resulting in blocking YAP/TAZ translocation from cytoplasm to nucleus. This condition inhibited mitochondrial fusion and promoted mitochondrial fission, and ultimately improved fusion/fission balance and cellular homeostasis. To sum up, this work clarified the anti-fibrosis and mechanism of hucMSCs cultured from the 3D FloTrix miniSpin bioreactor. We hope to provide new ideas and new methods for the clinical transformation and industrialization of hucMSCs therapy.

Targeting cellular mitophagy as a strategy for human cancers

Mitophagy is the cellular process to selectively eliminate dysfunctional mitochondria, governing the number and quality of mitochondria. Dysregulation of mitophagy may lead to the accumulation of damaged mitochondria, which plays an important role in the initiation and development of tumors. Mitophagy includes ubiquitin-dependent pathways mediated by PINK1/Parkin and non-ubiquitin dependent pathways mediated by mitochondrial autophagic receptors including NIX, BNIP3, and FUNDC1. Cellular mitophagy widely participates in multiple cellular process including metabolic reprogramming, anti-tumor immunity, ferroptosis, as well as the interaction between tumor cells and tumor-microenvironment. And cellular mitophagy also regulates tumor proliferation and metastasis, stemness, chemoresistance, resistance to targeted therapy and radiotherapy. In this review, we summarized the underlying molecular mechanisms of mitophagy and discussed the complex role of mitophagy in diverse contexts of tumors, indicating it as a promising target in the mitophagy-related anti-tumor therapy.

Circ_0098823 binding with IGF2BP3 regulates DNM1L stability to promote metastasis of hepatocellular carcinoma via mitochondrial fission

Hepatocellular carcinoma (HCC) is highly metastatic and invasive. CircRNA participates in gene regulation of multiple tumor metastases, but little is known whether it is a bystander or an actual player in HCC metastasis. We aim to explore the molecular mechanisms of novel circRNAs in HCC metastasis. RT-qPCR was used to detect the expression of 13 circRNAs derived by the ERBB3 gene. The function of circ_0098823 and DNM1L in HCC cells were estimated by CCK-8, transwell assays, flow cytometry, electron microscope, and in vivo experiments. RNA binding protein of circ_0098823 was confirmed by RNA pull-down, mass spectrometry, and RNA immunoprecipitation. The expression of DNM1L after IGF2BP3 knockdown was detected by RT-qPCR and western blot. Circ_0098823 was significantly up-regulated both in HCC tissues and HGF induced cell lines. Circ_0098823 overexpression significantly enhanced proliferation, migration, and invasion but decreased apoptosis of HCC cells, particularly promoted mitochondrial fission. Compared with the control group, the tumors in the circ_0098823 knockdown mice were significantly smaller and lighter. Circ_0098823 silencing suppressed DNM1L expression, a key molecule for fission, which enhanced proliferation, migration and invasion, and inhibited apoptosis of HCC cell. IGF2BP3 was a binding protein of circ_0098823. The expression and mRNA stability of DNM1L were down-regulated by IGF2BP3 knockdown. IGF2BP3 knockdown significantly alleviated the excessive migration, invasion and apoptosis of HCC cells caused by circ_0098823 overexpression. This study uncovered a novel circ_0098823 with tumor-promoting effect, and the mechanism by which circ_0098823 participates in HCC progression through IGF2BP3-guided DNM1L. Our study broadens molecular understanding of HCC progression.

Melatonin alleviates glyphosate-induced testosterone synthesis inhibition via targeting mitochondrial function in roosters

Glyphosate (GLY) is a widely used herbicide that has been revealed to inhibit testosterone synthesis in humans and animals. Melatonin (MET) is an endogenous hormone that has been demonstrated to promote mammalian testosterone synthesis via protecting mitochondrial function. However, it remains unclear whether MET targets mitochondria to alleviate GLY-inhibited testosterone synthesis in avian. In this study, an avian model using 7-day-old rooster upon chronic exposure to GLY with the treatment of MET was designed to clarify this issue. Data first showed that GLY-induced testicular Leydig cell damage, structural damage of the seminiferous tubule, and sperm quality decrease were mitigated by MET. Transcriptomic analyses of the testicular tissues revealed the potentially critical role of mitophagy and steroid hormone biosynthesis in the process of MET counteracting GLY-induced testicular damage. Also, validation data demonstrated that the inhibition of testosterone synthesis due to GLY-induced mitochondrial dynamic imbalance and concomitant Parkin-dependent mitophagy activation is alleviated by MET. Moreover, GLY-induced oxidative stress in serum and testicular tissue were significantly reversed by MET. In summary, these findings demonstrate that MET effectively ameliorates GLY-inhibited testosterone synthesis by inhibiting mitophagy activation, which provides a promising remedy for the application of MET as a potential therapeutic agent to antagonize reproductive toxicity induced by GLY and similar contaminants.

The role of BCL2L13 in glioblastoma: turning a need into a target

Glioblastoma (GBM) is the most common aggressive central nervous system cancer. GBM has a high mortality rate, with a median survival time of 12-15 months after diagnosis. A poor prognosis and a shorter life expectancy may result from resistance to standard treatments such as radiation and chemotherapy. Temozolomide has been the mainstay treatment for GBM, but unfortunately, there are high rates of resistance with GBM bypassing apoptosis. A proposed mechanism for bypassing apoptosis is decreased ceramide levels, and previous research has shown that within GBM cells, B cell lymphoma 2-like 13 (BCL2L13) can inhibit ceramide synthase. This review aims to discuss the causes of resistance in GBM cells, followed by a brief description of BCL2L13 and an explanation of its mechanism of action. Further, lipids, specifically ceramide, will be discussed concerning cancer and GBM cells, focusing on ceramide synthase and its role in developing GBM. By gathering all current information on BCL2L13 and ceramide synthase, this review seeks to enable an understanding of these pieces of GBM in the hope of finding an effective treatment for this disease.

Mitochondrial stress: a key role of neuroinflammation in stroke

Stroke is a clinical syndrome characterized by an acute, focal neurological deficit, primarily caused by the occlusion or rupture of cerebral blood vessels. In stroke, neuroinflammation emerges as a pivotal event contributing to neuronal cell death. The occurrence and progression of neuroinflammation entail intricate processes, prominently featuring mitochondrial dysfunction and adaptive responses. Mitochondria, a double membrane-bound organelle are recognized as the "energy workshop" of the body. Brain is particularly vulnerable to mitochondrial disturbances due to its high energy demands from mitochondria-related energy production. The interplay between mitochondria and neuroinflammation plays a significant role in the pathogenesis of stroke. The biological and pathological consequences resulting from mitochondrial stress have substantial implications for cerebral function. Mitochondrial stress serves as an adaptive mechanism aimed at mitigating the stress induced by the import of misfolded proteins, which occurs in response to stroke. This adaptive response involves a reduction in misfolded protein accumulation and overall protein synthesis. The influence of mitochondrial stress on the pathological state of stroke is underscored by its capacity to interact with neuroinflammation. The impact of mitochondrial stress on neuroinflammation varies according to its severity. Moderate mitochondrial stress can bolster cellular adaptive defenses, enabling cells to better withstand detrimental stressors. In contrast, sustained and excessive mitochondrial stress detrimentally affects cellular and tissue integrity. The relationship between neuroinflammation and mitochondrial stress depends on the degree of mitochondrial stress present. Understanding its role in stroke pathogenesis is instrumental in excavating the novel treatment of stroke. This review aims to provide the evaluation of the cross-talk between mitochondrial stress and neuroinflammation within the context of stroke. We aim to reveal how mitochondrial stress affects neuroinflammation environment in stroke.