Slc25a3-dependent copper transport controls flickering-induced Opa1 processing for mitochondrial safeguard

Copper Chelation Induces Morphology Change in Mitochondria of Triple-Negative Breast Cancer

Recent studies implicate mitochondria playing a key role in the cellular response to copper depletion therapy; however, evidence has been indirect and downstream, and the initial target of chelation remains to be defined. Here, we show, using super-resolution voltage and structure imaging microscopy, that copper chelation directly affects mitochondria morphology (causing fragmentation of the filamentous network) and ultrastructure (causing internal cristae remodeling). When triple-negative breast cancer cells are treated with a mitochondria-targeting copper chelator, mitochondria undergo an irreversible change in morphology from tubular to spherical. This process can be prevented by the addition of exogenous copper during the treatment. We find that a tailor-designed chelating agent with positive charges to target mitochondrial electrostatics localizes inside the mitochondrial cristae in a voltage-dependent manner. On pharmacological induction of membrane potential collapse, the chelator is dispersed while the mitochondrial cristae structure is preserved. These results indicate that voltage-dependent localization/targeting of the copper chelator in mitochondrial cristae plays a key role in its cytotoxicity.

Copper metabolism in hepatocellular carcinoma: from molecular mechanisms to therapeutic opportunities

Copper is a vital trace metal that facilitates cell proliferation, angiogenesis, and tumour spread. The liver is essential for copper metabolism, hence regulating copper levels is crucial for hepatic health. Hepatocellular carcinoma is a primary liver cancer characterised by a high death rate, and extensive research has shown the substantial impact of copper on its progression. This research primarily examines the molecular mechanisms involved, summarises the regulation of copper homeostasis, and addresses the role of copper metabolism in the promotion and inhibition of hepatocellular carcinoma development. Furthermore, it investigates prospective clinical approaches for targeting copper in the treatment of this disease, intending to establish a theoretical basis for the clinical use of copper in the management of hepatocellular carcinoma.

H2S remodels mitochondrial ultrastructure and destabilizes respiratory supercomplexes

Mitochondrial form and function are intimately interconnected, responding to cellular stresses and changes in energy demand. Hydrogen sulfide, a product of amino acid metabolism, has dual roles as an electron transport chain substrate and complex IV (CIV) inhibitor, leading to a reductive shift, which has pleiotropic metabolic consequences. Luminal sulfide concentration in the colon is high due to microbial activity, and in this study, we demonstrate that chronic sulfide exposure of colonocyte-derived cells leads to lower Mic60 and Mic19 expression that is correlated with a profound loss of cristae and lower mitochondrial networking. Sulfide-induced depolarization of the inner mitochondrial membrane activates Oma1-dependent cleavage of Opa1 and is associated with a profound loss of CI and CIV activities associated with respirasomes. Our study reveals a potential role for sulfide as an endogenous modulator of mitochondrial dynamics and suggests that this regulation is corrupted in hereditary or acquired diseases associated with elevated sulfide.

Copper doped bioactive glass promotes matrix vesicles-mediated biomineralization via osteoblast mitophagy and mitochondrial dynamics during bone regeneration

Bone defect repair remains a great challenge in the field of orthopedics. Human body essential trace element such as copper is essential for bone regeneration, but how to use it in bone defects and the underlying its mechanisms of promoting bone formation need to be further explored. In this study, by doping copper into mesoporous bioactive glass nanoparticles (Cu-MBGNs), we unveil a previously unidentified role of copper in facilitating osteoblast mitophagy and mitochondrial dynamics, which enhance amorphous calcium phosphate (ACP) release and subsequent biomineralization, ultimately accelerating the process of bone regeneration. Specifically, by constructing conditional knockout mice lacking the autophagy gene Atg5 in osteogenic lineage cells, we first confirmed the role of Cu-MBGNs-promoted bone formation via mediating osteoblast autophagy pathway. Then, the in vitro studies revealed that Cu-MBGNs strengthened mitophagy by inducing ROS production and recruiting PINK1/Parkin, thereby facilitating the efficient release of ACP from mitochondria into matrix vesicles for biomineralization during bone regeneration. Moreover, we found that Cu-MBGNs promoted mitochondrion fission via activating dynamin related protein 1 (Drp1) to reinforce mitophagy pathway. Together, this study highlights the potential of Cu-MBGNs-mediated mitophagy and biomineralization for augmenting bone regeneration, offering a promising avenue for the development of advanced bioactive materials in orthopedic applications.

Aconiti Lateralis Radix Praeparata ameliorates heart failure via PI3K/AKT/Bnip3 pathway

Background

Chronic heart failure (CHF) is one of the leading causes of high mortality worldwide. It is characterized by pathological hypertrophy and poses a major threat to human health. Aconiti Lateralis Radix Praeparata is widely used in ancient China to treat CHF. However, the pathology is obscured, necessitating further exploration.

Methods

Prospective targets were predicted by network analysis. A transverse aortic constriction (TAC) mice model was subsequently constructed to determine the effects of aqueous extract of Aconiti Lateralis Radix Praeparata (AEA) on CHF. The echocardiography was performed to investigate cardiac function. Histopathological analysis of cardiac tissue was conducted to assess myocardial fibrosis. Nontargeted metabolomics was performed to analyze serum metabolites. The phosphorylation level of PI3K and AKT, and downstream targets such as Bnip3, p62, Atg5, and LC3II were measured by Western blotting. In vitro, norepinephrine (NE) was used to stimulate cardiac hypertrophy. Parameters such as reactive oxygen species levels, mitochondrial membrane potential, ATP concentration, and CK/MB content were detected in H9c2 cells.

Results

AEA significantly alleviated CHF. Network analysis indicated the participation of AKT in CHF, and was modulated by Aconiti Lateralis Radix Praeparata. In vivo, AEA administration effectively ameliorated cardiac performance, evidenced by the elevation of ejection fraction. Histopathological analysis displayed a diminishment of collagen fiber. Metabolomics analysis showed that several metabolites such as tetrahydroxycorticosterone, decylubiquinone and taurocholic acid were increased in the TAC mice serum. Additionally, the phosphorylation levels of PI3K and AKT, and expression levels of Drp1, Opa1, Bnip3, p62, Atg5 and LC3II were altered in TAC group. In vitro, NE stimulation increased the cell surface area and deteriorated mitochondrial functions in H9c2 cells. However, AEA administration partially reversed such results, and the mechanism was associated with mitophagy.

Conclusion

This study revealed that AEA improved cardiac function via the PI3K/AKT/Bnip3 pathway.

Chinese sacbrood virus mediates m6A modification to target and suppress the expression of hemolymph maintenance gene AF9, exacerbating bee infections

The Chinese sacbrood virus (CSBV) severely threatens the beekeeping industry, wherein 3- to 5-day-old larvae in the critical differentiation stage are highly susceptible to low levels of CSBV exposure. Once infected, larvae cannot undergo normal pupation, but the pathogenic mechanism remains unclear. Previous studies have shown that m6A modification plays an important regulatory role in larval development during the critical differentiation stage. However, it is unknown whether CSBV infection affects the pupation of honeybee larvae by altering m6A modification. Here, a novel immunoregulatory factor, AF9, was identified in honeybee larvae through combined methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq analysis following CSBV infection. Enzyme-linked immunosorbent assay (ELISA) quantification of m6A methylation in total RNA and MeRIP-qPCR further revealed that CSBV infection of honeybee larvae inhibits the expression of AF9 via m6A modification, thereby hindering the host innate immune response and promoting CSBV replication. MeRIP-qPCR was then used to demonstrate that AcMETTL3 targets and modifies AF9 mRNA, thereby inhibiting AF9 expression. Homology and functional analysis of human-derived AF9 (MLLT3) suggested that AF9 exerted a similar effect as MLLT3 on honeybee hemolymph functioning. dsRNA was then fed to silence genes, followed by RNA extraction and expression analysis from hemolymph. Downregulation of AF9 expression led to decreased numbers of live cells in the hemolymph of honeybee larvae and a reduction in phenoloxidase activity, thereby inhibiting the host immune response. Finally, an Apis mellifera pupation infection model was constructed to further explore the antiviral activities associated with AmAF9. AmAF9 exerted a similarly significant antiviral effect against deformed wing virus (DWV) and acute bee paralysis virus (ABPV) infections in Apis mellifera pupae. These results indicate that CSBV infection promotes overall m6A modification in the host and inhibits the expression of AF9 through AcMETTL3 targeting, leading to host immunosuppression and exacerbating honeybee infection. Similarly, AF9 is stably expressed in Apis mellifera and exhibits the same antiviral effect, making it a broad-spectrum target in honeybee viruses.

IMPORTANCE

The Chinese sacbrood virus (CSBV) poses a serious threat to the health of Apis cerana colonies, yet its specific pathogenic mechanism remains unclear. This study shows that infection with CSBV can enhance overall m6A modification levels in Apis cerana larvae and suppress the expression of AF9 by promoting targeting of AcMETTL3, thereby inhibiting the innate immune response and exacerbating CSBV infection. Further analyses indicated that AF9 functions similarly as the mammalian homologous gene MLLT3 by maintaining normal functions of hemolymph. Moreover, AF9 can also significantly inhibit infections by common Apis mellifera viruses. In summary, a new mechanism is detailed here by which CSBV escapes the host's innate immune response by enhancing m6A modification to target and suppress the immune response gene AF9. This study also provides new insights into the mechanisms by which bee viruses inhibit host immune responses and suggests that AF9 may serve as a potential new broad-spectrum antiviral target in bees.

Macrophage-derived mitochondria-rich extracellular vesicles aggravate bone loss in periodontitis by disrupting the mitochondrial dynamics of BMSCs

BACKGROUND

Periodontitis is the leading cause of tooth loss in adults due to progressive bone destruction, which is closely related to the dysfunction of bone mesenchymal stem cells (BMSCs). Existing evidence suggests that mitochondrial disorders are associated with periodontitis. However, whether mitochondrial dysregulation contributes to the osteogenic impairment of BMSCs and the underlying mechanisms remain unclear. Macrophages have been shown to communicate extensively with BMSCs in periodontitis. Recent studies have reported a novel manner of cellular communication in which mitochondria-rich extracellular vesicles（MEVs） transfer mitochondria from parent cells to recipient cells, playing a role in both physiological and pathological conditions. Therefore, we aimed to investigate the role of MEVs in orchestrating the crosstalk between macrophages and BMSCs in periodontitis to formulate management strategies for bone loss.

RESULTS

Our results revealed that macrophages underwent significant mitochondrial dysfunction and inflammation in periodontitis and that MEVs derived from these macrophages played a role in alveolar bone destruction. Furthermore, cell imaging showed that inflammatory macrophages packaged numerous damaged mitochondria into MEVs, and the entry of these impaired mitochondria into BMSCs disrupted mitochondrial dynamics and hindered donut-shaped mitochondria formation, leading to osteogenic dysfunction. Proteomic analysis revealed that the proteins enriched in macrophage-derived MEVs were largely related to mitochondria and the formation and transport of vesicles. Additionally, we found that MEVs from macrophages significantly increased lipocalin 2 (LCN2) in BMSCs in periodontitis and that LCN2 perturbed mitochondrial morphological changes in BMSCs by inducing the degradation of OMA1 and accumulation of OPA1, resulting in osteogenesis impairment in BMSCs. Inhibition of LCN2 rescued the osteogenic dysfunction of BMSCs and alveolar bone loss in periodontitis.

CONCLUSIONS

The transfer of mitochondria to BMSCs via MEVs exacerbates alveolar bone resorption through LCN2/OMA1/OPA1 signaling in periodontitis. Inhibition of LCN2 alleviates inflammatory bone loss, suggesting a promising therapeutic strategy for periodontitis.

Dual regulation of mitochondrial fusion by Parkin-PINK1 and OMA1

Mitochondrial stress pathways protect mitochondrial health from cellular insults1-8. However, their role under physiological conditions is largely unknown. Here, using 18 single, double and triple whole-body and tissue-specific knockout and mutant mice, along with systematic mitochondrial morphology analysis, untargeted metabolomics and RNA sequencing, we discovered that the synergy between two stress-responsive systems-the ubiquitin E3 ligase Parkin and the metalloprotease OMA1-safeguards mitochondrial structure and genome by mitochondrial fusion, mediated by the outer membrane GTPase MFN1 and the inner membrane GTPase OPA1. Whereas the individual loss of Parkin or OMA1 does not affect mitochondrial integrity, their combined loss results in small body size, low locomotor activity, premature death, mitochondrial abnormalities and innate immune responses. Thus, our data show that Parkin and OMA1 maintain a dual regulatory mechanism that controls mitochondrial fusion at the two membranes, even in the absence of extrinsic stress.

GRHL2-HER3 and E-cadherin mediate EGFR-bypass drug resistance in lung cancer cells

Epidermal growth factor receptor (EGFR) is a major oncogenic protein, and thus EGFR-targeting therapies are widely used in patients with various types of cancer, including lung cancer. However, resistance to EGFR inhibitors, such as erlotinib, presents a significant challenge in treating lung cancer. In this study, we established an EGFR-independent, erlotinib-resistant (ER) phenotype in lung cancer A549 cells by exposing them to erlotinib for an extended period. The resulting ER cells exhibited a dramatic increase in erlotinib resistance, a decreased EGFR protein level, and enhanced tumor growth, suggesting a robust mechanism bypassing EGFR inhibition. RNA sequencing identified the transcription factor GRHL2 as a critical player in this resistance. GRHL2 was upregulated in ER cells, and its knockdown and knockout significantly reduced erlotinib resistance. Further analysis revealed that GRHL2 upregulates the receptor tyrosine kinase HER3, and that HER3 knockdown similarly decreases the IC50 for erlotinib. Additionally, ER cells showed increased cell-cell adhesion, linked to upregulated E-cadherin. E-cadherin was found to be vital for erlotinib resistance, largely independent of GRHL2, highlighting multiple parallel pathways sustaining resistance. These findings provide a novel mechanism of drug resistance and suggest that combination therapies targeting both GRHL2-HER3 and E-cadherin-mediated pathways may be necessary to overcome erlotinib resistance in lung cancer.

Mammalian copper homeostasis: physiological roles and molecular mechanisms

In the past decade, evidence for the numerous roles of copper (Cu) in mammalian physiology has grown exponentially. The discoveries of Cu involvement in cell signaling, autophagy, cell motility, differentiation, and regulated cell death (cuproptosis) have markedly extended the list of already known functions of Cu, such as a cofactor of essential metabolic enzymes, a protein structural component, and a regulator of protein trafficking. Novel and unexpected functions of Cu transporting proteins and enzymes have been identified, and new disorders of Cu homeostasis have been described. Significant progress has been made in the mechanistic studies of two classic disorders of Cu metabolism, Menkes disease and Wilson's disease, which paved the way for novel approaches to their treatment. The discovery of cuproptosis and the role of Cu in cell metastatic growth have markedly increased interest in targeting Cu homeostatic pathways to treat cancer. In this review, we summarize the established concepts in the field of mammalian Cu physiology and discuss how new discoveries of the past decade expand and modify these concepts. The roles of Cu in brain metabolism and in cell functional speciation and a recently discovered regulated cell death have attracted significant attention and are highlighted in this review.

H 2 S remodels mitochondrial ultrastructure and destabilizes respiratory supercomplexes

Mitochondrial form and function are intimately interconnected, responding to cellular stresses and changes in energy demand. Hydrogen sulfide, a product of amino acid metabolism, has dual roles as an electron transport chain substrate and complex IV (CIV) inhibitor, leading to a reductive shift, which has pleiotropic metabolic consequences. Luminal sulfide concentration in colon is high due to microbial activity, and in this study, we demonstrate that chronic sulfide exposure of colonocyte-derived cells leads to lower Mic60 and Mic19 expression that is correlated with a profound loss of cristae and lower mitochondrial networking. Sulfide-induced depolarization of the inner mitochondrial membrane activates Oma1-dependent cleavage of Opa1 and is associated with a profound loss of CI and CIV activities associated with respirasomes. Our study reveals a potential role for sulfide as an endogenous modulator of mitochondrial dynamics and suggests that this regulation is corrupted in hereditary or acquired diseases associated with elevated sulfide.

Significance Statement

Hydrogen sulfide is a product of host as well as gut microbial metabolism and has the dual capacity for activating respiration as a substrate, and inhibiting it at the level of complex IV. In this study, we report that chronic albeit low-level sulfide exposure elicits profound changes in mitochondrial architecture in cultured human cells. Disruption of mitochondrial networks is reversed upon removal of sulfide from the growth chamber atmosphere. Sulfide-dependent depolarization of the inner mitochondrial membrane is associated with loss of cristae and respiratory supercomplexes. Our study reveals the potential for sulfide to be an endogenous regulator of mitochondrial ultrastructure and function via modulation of electron flux and for this process to be corrupted in sulfide dysregulated diseases.

mCAUSE: Prioritizing mitochondrial targets that alleviate pancreatic cancer cell phenotypes

Substantial changes in energy metabolism are a hallmark of pancreatic cancer. To adapt to hypoxic and nutrient-deprived microenvironments, pancreatic cancer cells remodel their bioenergetics from oxidative phosphorylation to glycolysis. This bioenergetic shift makes mitochondria an Achilles' heel. Since mitochondrial function remains essential for pancreatic cancer cells, further depleting mitochondrial energy production is an appealing treatment target. However, identifying effective mitochondrial targets for treatment is challenging. Here, we developed an approach, mitochondria-targeted cancer analysis using survival and expression (mCAUSE), to prioritize target proteins from the entire mitochondrial proteome. Selected proteins were further tested for their impact on pancreatic cancer cell phenotypes. We discovered that targeting a dynamin-related GTPase, OPA1, which controls mitochondrial fusion and cristae, effectively suppresses pancreatic cancer activities. Remarkably, when combined with a mutation-specific KRAS inhibitor, OPA1 inhibition showed a synergistic effect. Our findings offer a therapeutic strategy against pancreatic cancer by simultaneously targeting mitochondria dynamics and KRAS signaling.