Mitochondrial dynamics during cell cycling

Impdh2 deficiency suppresses osteoclastogenesis through mitochondrial oxidative phosphorylation and alleviates ovariectomy-induced osteoporosis

Abnormalities in osteoclastic generation or activity disrupt bone homeostasis and are highly involved in many pathologic bone-related diseases, including rheumatoid arthritis, osteopetrosis, and osteoporosis. Control of osteoclast-mediated bone resorption is crucial for treating these bone diseases. However, the mechanisms of control of osteoclastogenesis are incompletely understood. In this study, we identified that inosine 5'-monophosphate dehydrogenase type II (Impdh2) positively regulates bone resorption. By histomorphometric analysis, Impdh2 deletion in mouse myeloid lineage cells (Impdh2LysM-/- mice) showed a high bone mass due to the reduced osteoclast number. qPCR and western blotting results demonstrated that the expression of osteoclast marker genes, including Nfatc1, Ctsk, Calcr, Acp5, Dcstamp, and Atp6v0d2, was significantly decreased in the Impdh2LysM-/- mice. Furthermore, the Impdh inhibitor MPA treatment inhibited osteoclast differentiation and induced Impdh2-cytoophidia formation. The ability of osteoclast differentiation was recovered after MPA deprivation. Interestingly, genome-wide analysis revealed that the osteoclastic mitochondrial biogenesis and functions, such as oxidative phosphorylation, were impaired in the Impdh2LysM-/- mice. Moreover, the deletion of Impdh2 alleviated ovariectomy-induced bone loss. In conclusion, our findings revealed a previously unrecognized function of Impdh2, suggesting that Impdh2-mediated mechanisms represent therapeutic targets for osteolytic diseases.

Mitochondrial dysfunction of peripheral blood mononuclear cells is associated with lung carcinogenesis

The composition, quantity, and function of peripheral blood mononuclear cells (PBMCs) are closely correlated with tumorigenesis. However, the mechanisms of PBMCs in lung cancer are not clear. Mitochondria are energy factories of cells, and almost all cellular functions rely on their energy metabolism level. The present study aimed to test whether the mitochondrial function of PBMCs directly determines their tumor immune monitoring function. We recruited 211 subjects, including 105 healthy controls and 106 patients with recently diagnosed with lung cancer. The model of lung carcinogenesis induced by BaP was used in animal experiment, and the Bap carcinogenic metabolite, Benzo(a)pyren-7,8-dihydrodiol-9,10-epoxide (BPDE), was used in cell experiment. We found that mitochondrial function of PBMCs decreased significantly in patients with new lung cancer, regardless of age. In vivo, BaP caused PBMC mitochondrial dysfunction in mice before the appearance of visible malignant tissue. Moreover, mitochondrial function decreased significantly in mice with lung cancers induced by BaP compared to those without lung cancer after BaP intervention. In vitro, BPDE also induced mitochondrial dysfunction and reduced the aggressiveness of PBMCs toward cancer cells. Furthermore, the changes in mitochondrial energy metabolism gene expression caused by BPDE are involved in this process. Thus, the mitochondrial function of PBMCs is a potential prognostic biomarker or therapeutic target to improve clinical outcomes in patients with lung cancer.

Unlocking Mitochondrial Dysfunction-Associated Senescence (MiDAS) with NAD + - a Boolean Model of Mitochondrial Dynamics and Cell Cycle Control

The steady accumulation of senescent cells with aging creates tissue environments that aid cancer evolution. Aging cell states are highly heterogeneous. 'Deep senescent' cells rely on healthy mitochondria to fuel a strong proinflammatory secretome, including cytokines, growth and transforming signals. Yet, the physiological triggers of senescence such as the reactive oxygen species (ROS) can also trigger mitochondrial dysfunction, and sufficient energy deficit to alter their secretome and cause chronic oxidative stress - a state termed Mitochondrial Dysfunction-Associated Senescence (MiDAS). Here, we offer a mechanistic hypothesis for the molecular processes leading to MiDAS, along with testable predictions. To do this we have built a Boolean regulatory network model that qualitatively captures key aspects of mitochondrial dynamics during cell cycle progression (hyper-fusion at the G1/S boundary, fission in mitosis), apoptosis (fission and dysfunction) and glucose starvation (reversible hyper-fusion), as well as MiDAS in response to SIRT3 knockdown or oxidative stress. Our model reaffirms the protective role of NAD + and external pyruvate. We offer testable predictions about the growth factor- and glucose-dependence of MiDAS and its reversibility at different stages of reactive oxygen species (ROS)-induced senescence. Our model provides mechanistic insights into the distinct stages of DNA-damage induced senescence, the relationship between senescence and epithelial-to-mesenchymal transition in cancer and offers a foundation for building multiscale models of tissue aging.

Highlights

Boolean regulatory network model reproduces mitochondrial dynamics during cell cycle progression, apoptosis, and glucose starvation. Model offers a mechanistic explanation for the positive feedback loop that locks in Mitochondrial Dysfunction-Associated Senescence (MiDAS), involving autophagy-resistant, hyperfused, dysfunctional mitochondria. Model reproduces ROS-mediated mitochondrial dysfunction and suggests that MiDAS is part of the early phase of damage-induced senescence. Model predicts that cancer-driving mutations that bypass the G1/S checkpoint generally increase the incidence of MiDAS, except for p53 loss.

Mitochondrial dysfunction: A promising therapeutic target for liver diseases

The liver is an important metabolic and detoxification organ and hence demands a large amount of energy, which is mainly produced by the mitochondria. Liver tissues of patients with alcohol-related or non-alcohol-related liver diseases contain ultrastructural mitochondrial lesions, mitochondrial DNA damage, disturbed mitochondrial dynamics, and compromised ATP production. Overproduction of mitochondrial reactive oxygen species induces oxidative damage to mitochondrial proteins and mitochondrial DNA, decreases mitochondrial membrane potential, triggers hepatocyte inflammation, and promotes programmed cell death, all of which impair liver function. Mitochondrial DNA may be a potential novel non-invasive biomarker of the risk of progression to liver cirrhosis and hepatocellular carcinoma in patients infected with the hepatitis B virus. We herein present a review of the mechanisms of mitochondrial dysfunction in the development of acute liver injury and chronic liver diseases, such as hepatocellular carcinoma, viral hepatitis, drug-induced liver injury, alcoholic liver disease, and non-alcoholic fatty liver disease. This review also discusses mitochondrion-centric therapies for treating liver diseases.

Disturbance of mitochondrial dynamics in myocardium of broilers with pulmonary hypertension syndrome

1. The following study investigated the relationship between pulmonary hypertension syndrome (PHS) and mitochondrial dynamics in broiler cardiomyocytes.2. An animal model for PHS was established by injecting broiler chickens with CM-32 cellulose particles. Broiler myocardial cells were cultured under hypoxic conditions to establish an in vitro model. The ascites heart index, histomorphology, mitochondrial ultrastructure, and mitochondrial dynamic-related gene and protein expression were evaluated.3. The myocardial fibres from PHS broilers had wider spaces and were wavy and twisted and the number of mitochondria increased. Compared with the control group, the gene and protein expression levels were decreased for Opa1, Mfn1, and Mfn2 in the myocardium of PHS broilers. The gene and protein expression was significantly increased for Drp1 and Mff.4. This study showed that PHS in broilers may cause myocardial mitochondrial dysfunction, specifically by diminishing mitochondrial fusion and enhancing fission, causing disturbances in the mitochondrial dynamics of the heart.

Mitochondrial deoxyguanosine kinase is required for female fertility in mice

Mitochondrial homeostasis plays a pivotal role in oocyte maturation and embryonic development. Deoxyguanosine kinase (DGUOK) is a nucleoside kinase that salvages purine nucleosides in mitochondria and is critical for mitochondrial DNA replication and homeostasis in non-proliferating cells. Dguok loss-of-function mutations and deletions lead to hepatocerebral mitochondrial DNA deletion syndrome. However, its potential role in reproduction remains largely unknown. In this study, we find that Dguok knockout results in female infertility. Mechanistically, DGUOK deficiency hinders ovarian development and oocyte maturation. Moreover, DGUOK deficiency in oocytes causes a significant reduction in mitochondrial DNA copy number and abnormal mitochondrial dynamics and impairs germinal vesicle breakdown. Only few DGUOK-deficient oocytes can extrude their first polar body during in vitro maturation, and these oocytes exhibit irregular chromosome arrangements and different spindle lengths. In addition, DGUOK deficiency elevates reactive oxygen species levels and accelerates oocyte apoptosis. Our findings reveal novel physiological roles for the mitochondrial nucleoside salvage pathway in oocyte maturation and implicate DGUOK as a potential marker for the diagnosis of female infertility.

Discovery of an antitumor compound from xenorhabdus stockiae HN_xs01

Xenorhabdus, known for its symbiotic relationship with Entomopathogenic nematodes (EPNs), belongs to the Enterobacteriaceae family. This dual-host symbiotic nematode exhibits pathogenic traits, rendering it a promising biocontrol agent against insects. Our prior investigations revealed that Xenorhabdus stockiae HN_xs01, isolated in our laboratory, demonstrates exceptional potential in halting bacterial growth and displaying anti-tumor activity. Subsequently, we separated and purified the supernatant of the HN_xs01 strain and obtained a new compound with significant inhibitory activity on tumor cells, which we named XNAE. Through LC-MS analysis, the mass-to-nucleus ratio of XNAE was determined to be 254.24. Our findings indicated that XNAE exerts a time- and dose-dependent inhibition on B16 and HeLa cells. After 24 h, its IC50 for B16 and HeLa cells was 30.178 µg/mL and 33.015 µg/mL, respectively. Electron microscopy revealed conspicuous damage to subcellular structures, notably mitochondria and the cytoskeleton, resulting in a notable reduction in cell numbers among treated tumor cells. Interestingly, while XNAE exerted a more pronounced inhibitory effect on B16 cells compared to HeLa cells, it showed no discernible impact on HUVEC cells. Treatment of B16 cells with XNAE induced early apoptosis and led to cell cycle arrest in the G2 phase, as evidenced by flow cytometry analysis. The impressive capability of X. stockiae HN_xs01 in synthesizing bioactive secondary metabolites promises to significantly expand the reservoir of natural products. Further exploration to identify the bioactivity of these compounds holds the potential to shed light on their roles in bacteria-host interaction. Overall, these outcomes underscore the promising potential of XNAE as a bioactive compound for tumor treatment.

Molecular Insights into the Synergistic Effects of Putrescine and Ammonium on Dinoflagellates

Ammonium and polyamines are essential nitrogen metabolites in all living organisms. Crosstalk between ammonium and polyamines through their metabolic pathways has been demonstrated in plants and animals, while no research has been directed to explore this relationship in algae or to investigate the underlying molecular mechanisms. Previous research demonstrated that high concentrations of ammonium and putrescine were among the active substances in bacteria-derived algicide targeting dinoflagellates, suggesting that the biochemical inter-connection and/or interaction of these nitrogen compounds play an essential role in controlling these ecologically important algal species. In this research, putrescine, ammonium, or a combination of putrescine and ammonium was added to cultures of three dinoflagellate species to explore their effects. The results demonstrated the dose-dependent and species-specific synergistic effects of putrescine and ammonium on these species. To further explore the molecular mechanisms behind the synergistic effects, transcriptome analysis was conducted on dinoflagellate Karlodinium veneficum treated with putrescine or ammonium vs. a combination of putrescine and ammonium. The results suggested that the synergistic effects of putrescine and ammonium disrupted polyamine homeostasis and reduced ammonium tolerance, which may have contributed to the cell death of K. veneficum. There was also transcriptomic evidence of damage to chloroplasts and impaired photosynthesis of K. veneficum. This research illustrates the molecular mechanisms underlying the synergistic effects of the major nitrogen metabolites, ammonium and putrescine, in dinoflagellates and provides direction for future studies on polyamine biology in algal species.

The role of mitochondrial dysfunction in macrophages on SiO2 -induced pulmonary fibrosis: A review

Several epidemiologic and toxicological studies have widely regarded that mitochondrial dysfunction is a popular molecular event in the process of silicosis from different perspectives, but the details have not been systematically summarized yet. Thus, it is necessary to investigate how silica dust leads to pulmonary fibrosis by damaging the mitochondria of macrophages. In this review, we first introduce the molecular mechanisms that silica dust induce mitochondrial morphological and functional abnormalities and then introduce the main molecular mechanisms that silica-damaged mitochondria induce pulmonary fibrosis. Finally, we conclude that the mitochondrial abnormalities of alveolar macrophages caused by silica dust are involved deeply in the pathogenesis of silicosis through these two sequential mechanisms. Therefore, reducing the silica-damaged mitochondria will prevent the potential occurrence and fatality of the disease in the future.

Reactive Oxygen Species Damage Bovine Endometrial Epithelial Cells via the Cytochrome C-mPTP Pathway

After parturition, bovine endometrial epithelial cells (BEECs) undergo serious inflammation and imbalance between oxidation and antioxidation, which is widely acknowledged as a primary contributor to the development of endometritis in dairy cows. Nevertheless, the mechanism of oxidative stress-mediated inflammation and damage in bovine endometrial epithelial cells remains inadequately defined, particularly the molecular pathways associated with mitochondria-dependent apoptosis. Hence, the present study was designed to explore the mechanism responsible for mitochondrial dysfunction-induced BEEC damage. In vivo, the expressions of proapoptotic protein caspase 3 and cytochrome C were increased significantly in dairy uteri with endometritis. Similarly, the levels of proapoptotic protein caspase 3, BAX, and cytochrome C were markedly increased in H2O2-treated BEECs. Our findings revealed pronounced BEEC damage in dairy cows with endometritis, accompanied by heightened expression of cyto-C and caspase-3 both in vivo and in vitro. The reduction in apoptosis-related protein of BEECs due to oxidant injury was notably mitigated following N-acetyl-L-cysteine (NAC) treatment. Furthermore, mitochondrial vacuolation was significantly alleviated, and mitochondrial membrane potential returned to normal levels after the removal of ROS. Excessive ROS may be the main cause of mitochondrial dysfunction. Mitochondrial permeability transition pore (mPTP) blockade by cyclophilin D (CypD) knockdown with CSA significantly blocked the flow of cytochrome C (cyto-C) and Ca2+ to the cytoplasm from the mitochondria. Our results indicate that elevated ROS and persistent opening of the mPTP are the main causes of oxidative damage in BEECs. Collectively our results reveal a new mechanism involving ROS-mPTP signaling in oxidative damage to BEECs, which may be a potential avenue for the clinical treatment of bovine endometritis.

Cotadutide improves brown adipose tissue thermogenesis in obese mice

We studied the effect of cotadutide, a dual agonist glucagon-like peptide 1 (GLP1)/Glucagon, on interscapular brown adipose tissue (iBAT) remodeling and thermogenesis of obese mice. Twelve-week-old male C57BL/6 mice were fed a control diet (C group, n = 20) or a high-fat diet (HF group, n = 20) for ten weeks. Then, animals were redivided, adding cotadutide treatment: C, CC, HF, and HFC for four additional weeks. The multilocular brown adipocyte structure showed fat conversion (whitening), hypertrophy, and structural disarray in the HF group, which was reverted in cotadutide-treated animals. Cotadutide enhances the body temperature, thermogenesis, and sympathetic innervation (peroxisome proliferator-activated receptor-α, β3 adrenergic receptor, interleukin 6, and uncoupled protein 1), reduces pro-inflammatory markers (disintegrin and metallopeptidase domain, morphogenetic protein 8a, and neuregulin 4), and improves angiogenesis (vascular endothelial growth factor A, and perlecan). In addition, cotadutide enhances lipolysis (perilipin and cell death-inducing DNA fragmentation factor α), mitochondrial biogenesis (nuclear respiratory factor 1, transcription factor A mitochondrial, mitochondrial dynamin-like GTPase, and peroxisome proliferator-activated receptor gamma coactivator 1α), and mitochondrial fusion/fission (dynamin-related protein 1, mitochondrial fission protein 1, and parkin RBR E3 ubiquitin protein ligase). Cotadutide reduces endoplasmic reticulum stress (activating transcription factor 4, C/EBP homologous protein, and growth arrest and DNA-damage inducible), and extracellular matrix markers (lysyl oxidase, collagen type I α1, collagen type VI α3, matrix metallopeptidases 2 and 9, and hyaluronan synthases 1 and 2). In conclusion, the experimental evidence is compelling in demonstrating cotadutide's thermogenic effect on obese mice's iBAT, contributing to unraveling its action mechanisms and the possible translational benefits.

Comparison of cell viability methods for human mesenchymal/stromal stem cells and human A549 lung carcinoma cells after freeze-thaw stress

For the safety and efficacy of frozen cell therapy products, determination of cellular viability is key. However, results of cell viability measurements do not only depend on the cell line or on the inflicted stress, but also on the assay used, making inter-experimental comparisons difficult. The aim of this study was thus to assess commonly used viability assays in clinically relevant human mesenchymal/stromal stem cells and human A549 lung carcinoma cells. Post freeze-thaw stress viability and proliferation were evaluated under different conditions using trypan blue, acridine orange/DAPI stain, alamarBlue, ATP, and neutral red assays. Significant differences in cell viability between metabolic assays were observed, likely due to their distinct intrinsic detection mechanisms. Membrane-integrity based assays generally overestimated cell viabilities in this study. Furthermore, noticeable differences in inter-assay sensitivities were observed. These differences highlight that cell viability methods should be meticulously selected and their associated results carefully interpreted in a relevant context to ensure reliable conclusions. Indeed, although cell membrane integrity based assays are a popular choice to determine cellular quality attributes after freezing and thawing, we demonstrate that metabolic assays may be more suitable in this context.

COX17 acetylation via MOF-KANSL complex promotes mitochondrial integrity and function

Reversible acetylation of mitochondrial proteins is a regulatory mechanism central to adaptive metabolic responses. Yet, how such functionally relevant protein acetylation is achieved remains unexplored. Here we reveal an unprecedented role of the MYST family lysine acetyltransferase MOF in energy metabolism via mitochondrial protein acetylation. Loss of MOF-KANSL complex members leads to mitochondrial defects including fragmentation, reduced cristae density and impaired mitochondrial electron transport chain complex IV integrity in primary mouse embryonic fibroblasts. We demonstrate COX17, a complex IV assembly factor, as a bona fide acetylation target of MOF. Loss of COX17 or expression of its non-acetylatable mutant phenocopies the mitochondrial defects observed upon MOF depletion. The acetylation-mimetic COX17 rescues these defects and maintains complex IV activity even in the absence of MOF, suggesting an activatory role of mitochondrial electron transport chain protein acetylation. Fibroblasts from patients with MOF syndrome who have intellectual disability also revealed respiratory defects that could be restored by alternative oxidase, acetylation-mimetic COX17 or mitochondrially targeted MOF. Overall, our findings highlight the critical role of MOF-KANSL complex in mitochondrial physiology and provide new insights into MOF syndrome.

Targeting mitochondrial dynamics by AZD5363 in triple-negative breast cancer MDA-MB-231 cell-derived spheres

Breast cancer stem cells (BCSCs) have been suggested to contribute to chemotherapeutic resistance and disease relapse in breast cancer. Thus, BCSCs represent a promising target in developing novel breast cancer treatment strategies. Mitochondrial dynamics in BCSCs were recently highlighted as an available approach for targeting BCSCs. In this study, a three-dimensional (3D) cultured breast cancer stem cell spheres model was constructed. Mitochondrial dynamics and functions were analyzed by flow cytometry and confocal microscopy. We have demonstrated that the protein levels of FIS 1 and Mitofusin 1 were significantly increased in BCSCs. Moreover, Capivasertib (AZD5363) administration could suppress Mitofusin1 expression in BCSCs. Our use of MitoTracker Orange and annexin V double-staining assay suggested that AZD5363 could induce apoptosis in BCSCs. The sensitivity of stem cell spheres to doxorubicin was investigated by CCK8 assay, and our results indicated that AZD5363 could re-sensitize BCSCs to Doxo. Flow cytometry analysis identified doxo-induced CD44 and CD133 expression in BCSCs could be suppressed by AZD5363. In combination with AZD536, doxo-induced apoptosis in the BCSCs was significantly increased. In conclusion, our study explored, for the first time, that AZD5363 could target mitochondrial dynamics in 3D cultured stem cell spheres (BCSCs) by regulating Mitofusin.

Mitochondrial dynamics in health and disease: mechanisms and potential targets

Mitochondria are organelles that are able to adjust and respond to different stressors and metabolic needs within a cell, showcasing their plasticity and dynamic nature. These abilities allow them to effectively coordinate various cellular functions. Mitochondrial dynamics refers to the changing process of fission, fusion, mitophagy and transport, which is crucial for optimal function in signal transduction and metabolism. An imbalance in mitochondrial dynamics can disrupt mitochondrial function, leading to abnormal cellular fate, and a range of diseases, including neurodegenerative disorders, metabolic diseases, cardiovascular diseases and cancers. Herein, we review the mechanism of mitochondrial dynamics, and its impacts on cellular function. We also delve into the changes that occur in mitochondrial dynamics during health and disease, and offer novel perspectives on how to target the modulation of mitochondrial dynamics.

Integrated machine learning survival framework develops a prognostic model based on inter-crosstalk definition of mitochondrial function and cell death patterns in a large multicenter cohort for lower-grade glioma

BACKGROUND

Lower-grade glioma (LGG) is a highly heterogeneous disease that presents challenges in accurately predicting patient prognosis. Mitochondria play a central role in the energy metabolism of eukaryotic cells and can influence cell death mechanisms, which are critical in tumorigenesis and progression. However, the prognostic significance of the interplay between mitochondrial function and cell death in LGG requires further investigation.

METHODS

We employed a robust computational framework to investigate the relationship between mitochondrial function and 18 cell death patterns in a cohort of 1467 LGG patients from six multicenter cohorts worldwide. A total of 10 commonly used machine learning algorithms were collected and subsequently combined into 101 unique combinations. Ultimately, we devised the mitochondria-associated programmed cell death index (mtPCDI) using machine learning models that exhibited optimal performance.

RESULTS

The mtPCDI, generated by combining 18 highly influential genes, demonstrated strong predictive performance for prognosis in LGG patients. Biologically, mtPCDI exhibited a significant correlation with immune and metabolic signatures. The high mtPCDI group exhibited enriched metabolic pathways and a heightened immune activity profile. Of particular importance, our mtPCDI maintains its status as the most potent prognostic indicator even following adjustment for potential confounding factors, surpassing established clinical models in predictive strength.

CONCLUSION

Our utilization of a robust machine learning framework highlights the significant potential of mtPCDI in providing personalized risk assessment and tailored recommendations for metabolic and immunotherapy interventions for individuals diagnosed with LGG. Of particular significance, the signature features highly influential genes that present further prospects for future investigations into the role of PCD within mitochondrial function.

Direct Visualization and Restoration of Metallic Ion-Induced Subcellular Ultrastructural Remodeling

Analysis of cellular ultrastructure dynamics and metal ions' fate can provide insights into the interaction between living organisms and metal ions. Here, we directly visualize the distribution of biogenic metallic aggregates, ion-induced subcellular reorganization, and the corresponding regulation effect in yeast by the near-native 3D imaging approach, cryo-soft X-ray tomography (cryo-SXT). By comparative 3D morphometric assessment, we observe the gold ions disrupting cellular organelle homeostasis, resulting in noticeable distortion and folding of vacuoles, apparent fragmentation of mitochondria, extreme swelling of lipid droplets, and formation of vesicles. The reconstructed 3D architecture of treated yeast demonstrates ∼65% of Au-rich sites in the periplasm, a comprehensive quantitative assessment unobtained by TEM. We also observe some AuNPs in rarely identified subcellular sites, namely, mitochondria and vesicles. Interestingly, the amount of gold deposition is positively correlated with the volume of lipid droplets. Shifting the external starting pH to near-neutral results in the reversion of changes in organelle architectures, boosting the amount of biogenic Au nanoparticles, and increasing cell viability. This study provides a strategy to analyze the metal ions-living organism interaction from subcellular architecture and spatial localization perspectives.

Melatonin as mitochondria-targeted drug

Oxidative damage is associated to numerous diseases as well as aging development. Mitochondria found in most eukaryotic organisms to create the energy of the cell, generate free radicals during its action and they are chief targets of the oxidants. Mitochondrial activities outspread outside the borders of the cell and effect human physiology by modulating interactions among cells and tissues. Therefore, it has been implicated in several human disorders and conditions. Melatonin (MLT) is an endogenously created indole derivative that modifies several tasks, involving mitochondria-associated activities. These possessions make MLT a powerful defender against a selection of free radical-linked disorders. MLT lessens mitochondrial anomalies causing from extreme oxidative stress and may improve mitochondrial physiology. It is a potent and inducible antioxidant for mitochondria. MLT is produced in mitochondria of conceivably of all cells and it also appears to be a mitochondria directed antioxidant which has related defensive properties as the synthesized antioxidant molecules. This chapter summarizes the suggestion that MLT is produced in mitochondria as well as disorders of mitochondrial MLT production that may associate to a number of mitochondria-linked diseases. MLT as a mitochondria-targeted drug is also discussed.

TDP-43 is a potential marker of dopaminergic neuronal damage caused by atrazine exposure

Atrazine (ATR) is one of the herbicides widely used worldwide. Meanwhile, it is an environmental endocrine disruptor that can cross the blood-brain barrier and cause damage to the endocrine-nervous system, especially by affecting the normal secretion of dopamine (DA). Regrettably, effector markers and cascade response mechanisms in damaged dopaminergic neurons induced by ATR exposure remain elusive. In this paper, we focus on investigating aggregation and position change of transactive response DNA-binding protein-43 (TDP-43) after ATR exposure, and illustrating whether TDP-43 can serve as a potential marker of mitochondrial dysfunction which causes damage to dopaminergic neurons. In our study, we used rat adrenal pheochromocytoma cell line 12 (PC12) to establish an in vitro model of dopaminergic neurons. After PC12 was intervened by ATR, we found reduced DA cycling and DA levels, and that TDP-43 aggregated continuously in the cytoplasm and then translocated to mitochondria. Furthermore, the studies we have performed showed that the translocation can cause mitochondrial dysfunction through activating the unfolded mitochondrial protein response (UPRmt), ultimately causing damage to dopaminergic neuron. The research we have done suggests that TDP-43 can serve as a potential effector marker of dopaminergic neuron damaged caused by ATR exposure.

Mitochondrial division inhibitor (mdivi-1) inhibits proliferation and epithelial-mesenchymal transition via the NF-κB pathway in thyroid cancer cells

Excessively fragmented mitochondria have been reported in thyroid cancer (TC). Mitochondrial division inhibitor (mdivi-1), a putative inhibitor of dynamin-related protein 1 (Drp1), prevents mitochondrial fission and thereby restricts cell proliferation across several types of primary cancer. However, the role of mdivi-1 on TC has not been sufficiently studied. This research is intended to explore the therapeutic effect of mdivi-1 in TC cells. Results demonstrated that highly invasive TC cells displayed excessive mitochondrial fission with more fragmented mitochondria. Treatment with mdivi-1 inhibited mitochondrial fission in 8505C cells as indicated by transmission electron microscope (TEM). It also impaired the proliferation and increased apoptosis in 8505C and K1 cells as shown by plate cloning assay, cell viability assay, and apoptosis assay. Mdivi-1 treatment also attenuated migratory and invasive abilities in 8505C and K1 cells as shown by the transwell assay and the wound healing assay. And we noticed the same inhibition of mdivi-1 in cell migration and cell viability after the knockdown of Drp1 in 8505C cells. This demonstrated that mdivi-1 exerted an anti-tumor effect independently of Drp1 in 8505C cells. Moreover, mdivi-1 treatment reversed epithelial-mesenchymal transition (EMT) by inhibiting the NF-κB pathway in 8505C cells. The present findings demonstrate that mdivi-1 has a therapeutic role in thyroid carcinoma.

Parkin exerts the tumor-suppressive effect through targeting mitochondria

The role of PARKIN in Parkinson's disease is well established but its role in cancer has recently emerged. PARKIN serves as a tumor suppressor in many cancers and loses the tumor-suppressive function due to loss of heterozygosity and DNA copy number. But how PARKIN protects against cancer is poorly understood. Through the analysis of PARKIN substrates and their association with mitochondria, this viewpoint discussed that PARKIN exerts its anti-cancer activity through targeting mitochondria. Mitochondria function as a convergence point for many signaling pathways and biological processes, including apoptosis, cell cycle, mitophagy, energy metabolism, oxidative stress, calcium homeostasis, inflammation, and so forth. PARKIN participates in these processes through regulating its mitochondrial targets. Conversely, these mitochondrial substrates also influence the function of PARKIN under different cellular circumstances. We believe that future studies in this area may lead to novel therapeutic targets and strategies for cancer therapy.

Retrograde regulation of mitochondrial fission and epithelial to mesenchymal transition in hepatocellular carcinoma by GCN5L1

Metabolic reprogram is crucial to support cancer cell growth and movement as well as determine cell fate. Mitochondrial protein acetylation regulates mitochondrial metabolism, which is relevant to cancer cell migration and invasion. The functional role of mitochondrial protein acetylation on cancer cell migration remains unclear. General control of amino acid synthesis 5 like-1(GCN5L1), as the regulator of mitochondrial protein acetylation, functions on metabolic reprogramming in mouse livers. In this study, we find that GCN5L1 expression is significantly decreased in metastatic HCC tissues. Loss of GCN5L1 promotes reactive oxygen species (ROS) generation through enhanced fatty acid oxidation (FAO), followed by activation of cellular ERK and DRP1 to promote mitochondrial fission and epithelia to mesenchymal transition (EMT) to boost cell migration. Moreover, palmitate and carnitine-stimulated FAO promotes mitochondrial fission and EMT gene expression to activate HCC cell migration. On the other hand, increased cellular acetyl-CoA level, the product of FAO, enhances HCC cell migration. Taken together, our finding uncovers the metastasis suppressor role as well as the underlying mechanism of GCN5L1 in HCC and also provides evidence of FAO retrograde control of HCC metastasis.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

Comprehensive Analysis of Mitochondrial Dynamics Alterations in Heart Diseases

The most common alterations affecting mitochondria, and associated with cardiac pathological conditions, implicate a long list of defects. They include impairments of the mitochondrial electron transport chain activity, which is a crucial element for energy formation, and that determines the depletion of ATP generation and supply to metabolic switches, enhanced ROS generation, inflammation, as well as the dysregulation of the intracellular calcium homeostasis. All these signatures significantly concur in the impairment of cardiac electrical characteristics, loss of myocyte contractility and cardiomyocyte damage found in cardiac diseases. Mitochondrial dynamics, one of the quality control mechanisms at the basis of mitochondrial fitness, also result in being dysregulated, but the use of this knowledge for translational and therapeutic purposes is still in its infancy. In this review we tried to understand why this is, by summarizing methods, current opinions and molecular details underlying mitochondrial dynamics in cardiac diseases.

Integration of transcriptomic and proteomic analyses reveals protective mechanisms of N-acetylcysteine in indomethacin-stimulated enterocytes

Intestinal health is critical for the growth and development of humans and animals. Our previous study has demonstrated that indomethacin (IDMT) could induce intestinal injury in piglets, and N-acetylcysteine (NAC) supplementation contributed to alleviating intestinal injury induced by various stimuli. In this study, we investigated the mechanism of IDMT-induced cell death in IPEC-1 cell lines and explored the role of NAC by using transcriptomic and proteomic analyses. Results showed that cell viability was substantially reduced with the increasing concentrations of IDMT, whereas NAC significantly increased the survival rate of IPEC-1 cells regardless of its addition method. Transcriptomics and proteomics data indicated that terms, such as cell cycle, energy metabolism, and cell proliferation, were significantly enriched by Gene ontology and pathway analyses. Flow cytometer analysis showed that IDMT induced cell cycle arrest at G0/G1 phase. The expression of cell cycle regulatory proteins (CDK1, CCNA2, and CDC45) was decreased by IDMT stimulation. Importantly, NAC treatment repaired IDMT-induced mitochondrial dysfunction by increasing ATP production, decreasing oxygen consumption rate in non-mitochondrial O₂ consumption, and increasing the red/green fluorescence ratio. IDMT stimulation significantly increased caspase-3 expression, which was partially reversed by NAC treatment. These results suggest that IDMT-induced cell death may be attributable to disturbance of the cell cycle processes, mitochondria dysfunction and apoptosis, and NAC could confer a protective effect by restoring the mitochondrial function and inhibiting the apoptosis pathway. This study provides a theoretical basis for the pathogenesis of IDMT-induced intestinal injury and guides the clinic application of NAC.

Genome-wide characterization of mitochondrial DNA methylation in human brain

Background

There is growing interest in the role of DNA methylation in regulating the transcription of mitochondrial genes, particularly in brain disorders characterized by mitochondrial dysfunction. Here, we present a novel approach to interrogate the mitochondrial DNA methylome at single base resolution using targeted bisulfite sequencing. We applied this method to investigate mitochondrial DNA methylation patterns in post-mortem superior temporal gyrus and cerebellum brain tissue from seven human donors.

Results

We show that mitochondrial DNA methylation patterns are relatively low but conserved, with peaks in DNA methylation at several sites, such as within the D-LOOP and the genes MT-ND2, MT-ATP6, MT-ND4, MT-ND5 and MT-ND6, predominantly in a non-CpG context. The elevated DNA methylation we observe in the D-LOOP we validate using pyrosequencing. We identify loci that show differential DNA methylation patterns associated with age, sex and brain region. Finally, we replicate previously reported differentially methylated regions between brain regions from a methylated DNA immunoprecipitation sequencing study.

Conclusions

We have annotated patterns of DNA methylation at single base resolution across the mitochondrial genome in human brain samples. Looking to the future this approach could be utilized to investigate the role of mitochondrial epigenetic mechanisms in disorders that display mitochondrial dysfunction.

Autophagy Activation Associates with Suppression of Prion Protein and Improved Mitochondrial Status in Glioblastoma Cells

Cells from glioblastoma multiforme (GBM) feature up-regulation of the mechanistic Target of Rapamycin (mTOR), which brings deleterious effects on malignancy and disease course. At the cellular level, up-regulation of mTOR affects a number of downstream pathways and suppresses autophagy, which is relevant for the neurobiology of GBM. In fact, autophagy acts on several targets, such as protein clearance and mitochondrial status, which are key in promoting the malignancy GBM. A defective protein clearance extends to cellular prion protein (PrPc). Recent evidence indicates that PrPc promotes stemness and alters mitochondrial turnover. Therefore, the present study measures whether in GBM cells abnormal amount of PrPc and mitochondrial alterations are concomitant in baseline conditions and whether they are reverted by mTOR inhibition. Proteins related to mitochondrial turnover were concomitantly assessed. High amounts of PrPc and altered mitochondria were both mitigated dose-dependently by the mTOR inhibitor rapamycin, which produced a persistent activation of the autophagy flux and shifted proliferating cells from S to G1 cell cycle phase. Similarly, mTOR suppression produces a long-lasting increase of proteins promoting mitochondrial turnover, including Pink1/Parkin. These findings provide novel evidence about the role of autophagy in the neurobiology of GBM.

Antitumor Effects of Ononin by Modulation of Apoptosis in Non-Small-Cell Lung Cancer through Inhibiting PI3K/Akt/mTOR Pathway

Lung cancer is a leading global cause of cancer-related death in both males and females. Non-small-cell lung cancer (NSCLC) is the most commonly diagnosed cancer type that can be difficult to control with conventional chemotherapeutic and surgical approaches resulting in a poor prognosis. Paclitaxel (PTX) is a commonly used chemotherapeutic drug for NSCLC, which can cause tissue injury in healthy cells and affect the quality of life in patients with cancer. In order to treat NSCLC, alternative medications with minimal or no side effects are highly needed. Ononin is an isoflavone glycoside extracted from Astragali Radix (AR) that has various pharmacological activities. Therefore, this study investigated whether ononin inhibits NSCLC progression and promotes apoptosis synergistically with PTX both in vitro and in vivo. Antitumorigenic properties of ononin were determined by MTT assay, colony formation assay, migratory capacity, and apoptotic marker expression in A549 and HCC827 cells. The combination of ononin with PTX increased the expression of apoptotic markers and ROS generation and inhibited cell proliferation through the PI3K/Akt/mTOR signaling pathways. Furthermore, ononin prevented the translocation of NF-κB from cytosol to the nucleus. Also, we used the xenograft NSCLC mice model to confirm the in vivo antitumorigenic efficacies of ononin by reduction of CD34 and Ki67 expressions. Based on the histological analysis, the cotreatment of PTX and ononin reduced PTX-induced liver and kidney damage. Overall, our findings suggested that the therapeutic index of PTX-based chemotherapy could be improved by reducing toxicity with increasing antitumor capabilities when combined with ononin.

Rumen Epithelial Development- and Metabolism-Related Genes Regulate Their Micromorphology and VFAs Mediating Plateau Adaptability at Different Ages in Tibetan Sheep

The rumen is an important hallmark organ of ruminants and plays an important role in the metabolism and immune barrier of Tibetan sheep on the Plateau. However, there are few studies on rumen development and metabolism regulation in Tibetan sheep at different ages. Here, we comprehensively analyzed the immune function, fermentation function, rumen epithelial micromorphology and transcriptome profile of Tibetan sheep at different ages. The results showed that the concentration of IgG decreased and the concentration of IgM increased with age (p < 0.05), and the highest concentration of IgA was observed at 1.5 and 3.5 years of age. In terms of rumen fermentation characteristics, VFAs of 4-month-old lambs were the highest, followed by VFAs and NH3-N of Tibetan sheep at 3.5 years of age. Hematoxylin-eosin staining and transmission electron microscopy section examination of rumen epithelial tissue showed that the rumen papilla width increased with age (p < 0.001), the thickness of the stratum corneum decreased, the cells in the stratum corneum showed accelerated migration and the thickness of the rumen muscle layer increased (p < 0.001). Desmosomal junctions between the layers of rumen epithelium increased at 1.5 and 3.5 years old, forming a compact barrier structure, and the basal layer had more mitochondria involved in the regulation of energy metabolism. RNA-seq analysis revealed that a total of 1006 differentially expressed genes (DEGs) were identified at four ages. The DEGs of Tibetan sheep aged 4 months and 6 years were mainly enriched in the oxidation−reduction process and ISG15-protein conjugation pathway. The 1.5 and 3.5-year-olds were mainly enriched in skeletal muscle thin filament assembly, mesenchyme migration and the tight junction pathway. WGCNA showed that DEGs related to rumen microbiota metabolite VFAs and epithelial morphology were enriched in “Metabolism of xenobiotics by cytochrome P450, PPAR signaling pathway, Butanoate metabolism pathways” and participated in the regulation of rumen epithelial immune and fermentation metabolism functions of Tibetan sheep at different ages. This study systematically revealed the regulatory mechanism of rumen epithelial development and metabolism in the plateau adaptation of Tibetan sheep, providing a new approach for the study of plateau adaptation.

Role of Ceramides and Lysosomes in Extracellular Vesicle Biogenesis, Cargo Sorting and Release

Cells have the ability to communicate with their immediate and distant neighbors through the release of extracellular vesicles (EVs). EVs facilitate intercellular signaling through the packaging of specific cargo in all type of cells, and perturbations of EV biogenesis, sorting, release and uptake is the basis of a number of disorders. In this review, we summarize recent advances of the complex roles of the sphingolipid ceramide and lysosomes in the journey of EV biogenesis to uptake.

Novel DNM1L variants impair mitochondrial dynamics through divergent mechanisms

Novel DNM1L variants underlie a spectrum of clinical phenotypes and impair mitochondrial and peroxisomal dynamics via divergent mechanisms, with effects on DRP1 protein stability, GTPase activity, and oligomerisation in vitro.

Imbalances in mitochondrial and peroxisomal dynamics are associated with a spectrum of human neurological disorders. Mitochondrial and peroxisomal fission both involve dynamin-related protein 1 (DRP1) oligomerisation and membrane constriction, although the precise biophysical mechanisms by which distinct DRP1 variants affect the assembly and activity of different DRP1 domains remains largely unexplored. We analysed four unreported de novo heterozygous variants in the dynamin-1-like gene DNM1L, affecting different highly conserved DRP1 domains, leading to developmental delay, seizures, hypotonia, and/or rare cardiac complications in infancy. Single-nucleotide DRP1 stalk domain variants were found to correlate with more severe clinical phenotypes, with in vitro recombinant human DRP1 mutants demonstrating greater impairments in protein oligomerisation, DRP1-peroxisomal recruitment, and both mitochondrial and peroxisomal hyperfusion compared to GTPase or GTPase-effector domain variants. Importantly, we identified a novel mechanism of pathogenesis, where a p.Arg710Gly variant uncouples DRP1 assembly from assembly-stimulated GTP hydrolysis, providing mechanistic insight into how assembly-state information is transmitted to the GTPase domain. Together, these data reveal that discrete, pathological DNM1L variants impair mitochondrial network maintenance by divergent mechanisms.

CEND1 deficiency induces mitochondrial dysfunction and cognitive impairment in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of neurodegenerative disease featured with memory loss and cognitive function impairments. Chronic mitochondrial stress is a vital pathogenic factor for AD and finally leads to massive neuronal death. However, the underlying mechanism is unclear. By proteomic analysis, we identified a new mitochondrial protein, cell-cycle exit and neuronal differentiation 1 (CEND1), which was decreased significantly in the brain of 5xFAD mice. CEND1 is a neuronal specific protein and locates in the presynaptic mitochondria. Depletion of CEND1 leads to increased mitochondrial fission mediated by upregulation of dynamin related protein 1 (Drp1), resulting in abnormal mitochondrial functions. CEND1 deficiency leads to cognitive impairments in mice. Overexpression of CEND1 in the hippocampus of 5xFAD mice rescued cognitive deficits. Moreover, we identified that CDK5/p25 interacted with and phosphorylated CEND1 which promoted its degradation. Our study provides new mechanistic insights in mitochondrial function regulations by CEND1 in Alzheimer's disease.

The role of Mitochondrial Fission Proteins in Mitochondrial Dynamics in Kidney Disease

Mitochondria have many forms and can change their shape through fusion and fission of the outer and inner membranes, called "mitochondrial dynamics". Mitochondrial outer membrane proteins, such as mitochondrial fission protein 1 (FIS1), mitochondrial fission factor (MFF), mitochondrial 98 dynamics proteins of 49 kDa (MiD49), and mitochondrial dynamics proteins of 51 kDa (MiD51), can aggregate at the outer mitochondrial membrane and thus attract Dynamin-related protein 1 (DRP1) from the cytoplasm to the outer mitochondrial membrane, where DRP1 can perform a scissor-like function to cut a complete mitochondrion into two separate mitochondria. Other organelles can promote mitochondrial fission alongside mitochondria. FIS1 plays an important role in mitochondrial-lysosomal contacts, differentiating itself from other mitochondrial-fission-associated proteins. The contact between the two can also induce asymmetric mitochondrial fission. The kidney is a mitochondria-rich organ, requiring large amounts of mitochondria to produce energy for blood circulation and waste elimination. Pathological increases in mitochondrial fission can lead to kidney damage that can be ameliorated by suppressing their excessive fission. This article reviews the current knowledge on the key role of mitochondrial-fission-associated proteins in the pathogenesis of kidney injury and the role of their various post-translational modifications in activation or degradation of fission-associated proteins and targeted drug therapy.

Hyperinsulinemia-induced microglial mitochondrial dynamic and metabolic alterations lead to neuroinflammation in vivo and in vitro

Numerous studies have demonstrated that type 2 diabetes (T2D) is closely linked to the occurrence of Alzheimer’s disease (AD). Nevertheless, the underlying mechanisms for this association are still unknown. Insulin resistance (IR) hallmarked by hyperinsulinemia, as the earliest and longest-lasting pathological change in T2D, might play an important role in AD. Since hyperinsulinemia has an independent contribution to related disease progressions by promoting inflammation in the peripheral system, we hypothesized that hyperinsulinemia might have an effect on microglia which plays a crucial role in neuroinflammation of AD. In the present study, we fed 4-week-old male C57BL/6 mice with a high-fat diet (HFD) for 12 weeks to establish IR model, and the mice treated with standard diet (SD) were used as control. HFD led to obesity in mice with obvious glucose and lipid metabolism disorder, the higher insulin levels in both plasma and cerebrospinal fluid, and aberrant insulin signaling pathway in the whole brain. Meanwhile, IR mice appeared impairments of spatial learning and memory accompanied by neuroinflammation which was characterized by activated microglia and upregulated expression of pro-inflammatory factors in different brain regions. To clarify whether insulin contributes to microglial activation, we treated primary cultured microglia and BV2 cell lines with insulin in vitro to mimic hyperinsulinemia. We found that hyperinsulinemia not only increased microglial proliferation and promoted M1 polarization by enhancing the production of pro-inflammatory factors, but also impaired membrane translocation of glucose transporter 4 (GLUT4) serving as the insulin-responding glucose transporter in the processes of glucose up-taking, reduced ATP production and increased mitochondrial fission. Our study provides new perspectives and evidence for the mechanism underlying the association between T2D and AD.

Cytotoxicity, Mitochondrial Functionality, and Redox Status of Human Conjunctival Cells after Short and Chronic Exposure to Preservative-Free Bimatoprost 0.03% and 0.01%: An In Vitro Comparative Study

Prostaglandin analogues (PGAs), including bimatoprost (BIM), are generally the first-line therapy for glaucoma due to their greater efficacy, safety, and convenience of use. Commercial solutions of preservative-free BIM (BIM 0.03% and 0.01%) are already available, although their topical application may result in ocular discomfort. This study aimed to evaluate the in vitro effects of preservative-free BIM 0.03% vs. 0.01% in the human conjunctival epithelial (HCE) cell line. Our results showed that long-term exposure to BIM 0.03% ensues a significant decrease in cell proliferation and viability. Furthermore, these events were associated with cell cycle arrest, apoptosis, and alterations of ΔΨ_m. BIM 0.01% does not exhibit cytotoxicity, and no negative influence on conjunctival cell growth and viability or mitochondrial activity has been observed. Short-time exposure also demonstrates the ability of BIM 0.03% to trigger reactive oxygen species (ROS) production and mitochondrial hyperpolarisation. An in silico drug network interaction was also performed to explore known and predicted interactions of BIM with proteins potentially involved in mitochondrial membrane potential dissipation. Our findings overall strongly reveal better cellular tolerability of BIM 0.01% vs. BIM 0.03% in HCE cells.

Jian-Pi-Yi-Shen decoction inhibits mitochondria-dependent granulosa cell apoptosis in a rat model of POF

As a widely applied traditional Chinese medicine (TCM), Jian-Pi-Yi-Shen (JPYS) decoction maybe applied in curing premature ovarian failure (POF) besides chronic kidney disease (CKD). In vivo experiments, 40 female SD (8-week-old) rats were randomized into four groups, namely, control group (negative control), POF model group, JPYS treatment group, and triptorelin treatment group (positive control). JPYS group was treated with JPYS decoction (oral, 11 g/kg) for 60 days, and the triptorelin group was treated with triptorelin (injection, 1.5 mg/kg) for 10 days before the administration of cyclophosphamide (CTX) (50 mg/kg body weight) to establish POF model. We examined apoptosis, mitochondrial function, and target gene (ASK1/JNK pathway and mitochondrial fusion/fission) expression. In vitro experiments, the KGN human granulosa cell line was used. Cells were pretreated with CTX (20, 40, and 60 μg/mL) for 24 h, followed by JPYS-containing serum (2, 4, and 8 %) for 24 h. Thereafter, these cells were employed to assess apoptosis, mitochondrial function, and target gene levels of protein and mRNA. In vivo, JPYS alleviated injury and suppressed apoptosis in POF rats. In addition, JPYS improved ovarian function. JPYS inhibit apoptosis of granulosa cells through improving mitochondrial function by activating ASK1/JNK pathway. In vitro, JPYS inhibited KGN cell apoptosis through inhibited ASK1/JNK pathway and improved mitochondrial function. The effects of GS-49977 were similar to those of JPYS. During POF, mitochondrial dysfunction occurs in the ovary and leads to granulosa cell apoptosis. JPYS decoction improves mitochondrial function and alleviates apoptosis through ASK1/JNK pathway.

Depletion of ALMS1 affects TGF-β signalling pathway and downstream processes such as cell migration and adhesion capacity

Background: ALMS1 is a ubiquitous gene associated with Alström syndrome (ALMS). The main symptoms of ALMS affect multiple organs and tissues, generating at last, multi-organic fibrosis in the lungs, kidneys and liver. TGF-β is one of the main pathways implicated in fibrosis, controlling the cell cycle, apoptosis, cell migration, cell adhesion and epithelial-mesenchymal transition (EMT). Nevertheless, the role of ALMS1 gene in fibrosis generation and other implicated processes such as cell migration or cell adhesion via the TGF- β pathway has not been elucidated yet. Methods: Initially, we evaluated how depletion of ALMS1 affects different processes like apoptosis, cell cycle and mitochondrial activity in HeLa cells. Then, we performed proteomic profiling with TGF-β stimuli in HeLa ALMS1 -/- cells and validated the results by examining different EMT biomarkers using qPCR. The expression of these EMT biomarkers were also studied in hTERT-BJ-5ta ALMS1 -/-. Finally, we evaluated the SMAD3 and SMAD2 phosphorylation and cell migration capacity in both models. Results: Depletion of ALMS1 generated apoptosis resistance to thapsigargin (THAP) and C2-Ceramide (C2-C), and G2/M cell cycle arrest in HeLa cells. For mitochondrial activity, results did not show significant differences between ALMS1 +/+ and ALMS1 -/-. Proteomic results showed inhibition of downstream pathways regulated by TGF-β. The protein-coding genes (PCG) were associated with processes like focal adhesion or cell-substrate adherens junction in HeLa. SNAI1 showed an opposite pattern to what would be expected when activating the EMT in HeLa and BJ-5ta. Finally, in BJ-5ta model a reduced activation of SMAD3 but not SMAD2 were also observed. In HeLa model no alterations in the canonical TGF-β pathway were observed but both cell lines showed a reduction in migration capacity. Conclusion: ALMS1 has a role in controlling the cell cycle and the apoptosis processes. Moreover, the depletion of ALMS1 affects the signal transduction through the TGF-β and other processes like the cell migration and adhesion capacity.

Regulation of mitochondrial dysfunction induced cell apoptosis is a potential therapeutic strategy for herbal medicine to treat neurodegenerative diseases

Neurodegenerative disease is a progressive neurodegeneration caused by genetic and environmental factors. Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD) are the three most common neurodegenerative diseases clinically. Unfortunately, the incidence of neurodegenerative diseases is increasing year by year. However, the current available drugs have poor efficacy and large side effects, which brings a great burden to the patients and the society. Increasing evidence suggests that occurrence and development of the neurodegenerative diseases is closely related to the mitochondrial dysfunction, which can affect mitochondrial biogenesis, mitochondrial dynamics, as well as mitochondrial mitophagy. Through the disruption of mitochondrial homeostasis, nerve cells undergo varying degrees of apoptosis. Interestingly, it has been shown in recent years that the natural agents derived from herbal medicines are beneficial for prevention/treatment of neurodegenerative diseases via regulation of mitochondrial dysfunction. Therefore, in this review, we will focus on the potential therapeutic agents from herbal medicines for treating neurodegenerative diseases via suppressing apoptosis through regulation of mitochondrial dysfunction, in order to provide a foundation for the development of more candidate drugs for neurodegenerative diseases from herbal medicine.

The Role of Mitochondrial Quality Control in Anthracycline-Induced Cardiotoxicity: From Bench to Bedside

Cardiotoxicity is the major side effect of anthracyclines (doxorubicin, daunorubicin, epirubicin, and idarubicin), though being the most commonly used chemotherapy drugs and the mainstay of therapy in solid and hematological neoplasms. Advances in the field of cardio-oncology have expanded our understanding of the molecular mechanisms underlying anthracycline-induced cardiotoxicity (AIC). AIC has a complex pathogenesis that includes a variety of aspects such as oxidative stress, autophagy, and inflammation. Emerging evidence has strongly suggested that the loss of mitochondrial quality control (MQC) plays an important role in the progression of AIC. Mitochondria are vital organelles in the cardiomyocytes that serve as the key regulators of reactive oxygen species (ROS) production, energy metabolism, cell death, and calcium buffering. However, as mitochondria are susceptible to damage, the MQC system, including mitochondrial dynamics (fusion/fission), mitophagy, mitochondrial biogenesis, and mitochondrial protein quality control, appears to be crucial in maintaining mitochondrial homeostasis. In this review, we summarize current evidence on the role of MQC in the pathogenesis of AIC and highlight the therapeutic potential of restoring the cardiomyocyte MQC system in the prevention and intervention of AIC.

Fibroblast growth factor 21, a stress regulator, inhibits Drp1 activation to alleviate skeletal muscle ischemia/reperfusion injury

Abnormal Drp1 activation and subsequent excessive mitochondrial fission play a critical role in ischemia-reperfusion injury (I/RI). Although fibroblast growth factor 21 (FGF21) protects organs against I/RI and regulates metabolism, which indicates that FGF21 is involved in mitochondria homeostasis, the detailed mechanism remains unclear. Herein, we investigated whether FGF21 had an effect on Drp1 activation during skeletal muscle I/RI. Drp1 phosphorylation and its translocation to mitochondria, as regulated by FGF21, was examined in mouse and C2C12 cell I/RI models. Mice overexpressing FGF21 displayed alleviation of serum index, histological lesions and apoptosis levels. Moreover, FGF21 markedly decreased cyclin-dependent kinase 1 (CDK1) and Drp1 phosphorylation at Ser616, accompanied by reduced accumulation in mitochondria. In parallel in vitro studies, cells with FGF21 knockdown displayed enhanced Drp1 activation, and the reverse effect was found when FGF21 was added. More importantly, FGF21 attenuated mitochondrial fission with linear mitochondria rather than fragmented mitochondria. Furthermore, a CDK1 inhibitor reduced Drp1 activation and mitochondrial fission due to FGF21 knockdown. This study shows that FGF21 inhibits Drp1 activation to protect mitochondria from fission, thereby rescuing cells from I/RI-induced apoptosis. Our findings may provide a new therapeutic approach to ameliorate skeletal muscle I/RI.

Sphingosylphosphorylcholine ameliorates doxorubicin-induced cardiotoxicity in zebrafish and H9c2 cells by reducing excessive mitophagy and mitochondrial dysfunction

Doxorubicin (DOX, C₂₇H₂₉NO₁₁), is an anthracycline tumor chemotherapy drug, which has significant side effects on many organs including the heart. In recent years, mitochondrial dysfunction caused by DOX was identified as an important reason for cardiotoxic injury. Sphingosylphosphorylcholine (SPC) is essential for mitochondrial homeostasis in our previous report, however, its role in DOX-caused cardiomyopathy has remained elusive. Herein, DOX treated zebrafish embryos (90 μM) and adult fish (2.5 μM/g) were used to simulate DOX-induced cardiotoxic damage. Histopathological and ultrastructural observations showed that SPC (2.5 μM) significantly ameliorated DOX-induced pericardial edema, myocardial vacuolization and apoptosis. Furthermore, SPC (2.5 μM) can significantly inhibit DOX-induced apoptosis and promote cell proliferation in DOX treated H9c2 cells (1 μM), which is dependent on the restoration of mitochondrial homeostasis, including restored mitochondrial membrane potential, mitochondrial superoxide and ATP levels. We finally confirmed that SPC restored mitochondrial homeostasis through ameliorating DOX-induced excessive mitophagy. Mechanistically, SPC reduced calmodulin (CaM) levels and thus inhibiting Parkin activation and Parkin-dependent mitophagy. These results suggest that reducing the cardiotoxicity of chemotherapeutic drugs by targeting SPC may be a new solution to rescue chemotherapy injury.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

Mitochondrial Dysfunction Plays Central Role in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a global pandemic that affects one-quarter of the world’s population. NAFLD includes a spectrum of progressive liver disease from steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis and can be complicated by hepatocellular carcinoma. It is strongly associated with metabolic syndromes, obesity, and type 2 diabetes, and it has been shown that metabolic dysregulation is central to its pathogenesis. Recently, it has been suggested that metabolic- (dysfunction) associated fatty liver disease (MAFLD) is a more appropriate term to describe the disease than NAFLD, which puts increased emphasis on the important role of metabolic dysfunction in its pathogenesis. There is strong evidence that mitochondrial dysfunction plays a significant role in the development and progression of NAFLD. Impaired mitochondrial fatty acid oxidation and, more recently, a reduction in mitochondrial quality, have been suggested to play a major role in NAFLD development and progression. In this review, we provide an overview of our current understanding of NAFLD and highlight how mitochondrial dysfunction contributes to its pathogenesis in both animal models and human subjects. Further we discuss evidence that the modification of mitochondrial function modulates NAFLD and that targeting mitochondria is a promising new avenue for drug development to treat NAFLD/NASH.

Fine-tuning cell organelle dynamics during mitosis by small GTPases

During mitosis, the allocation of genetic material concurs with organelle transformation and distribution. The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression, cell fate determination, and organismal homeostasis. Small GTPases belonging to the Ras superfamily regulate various cell organelles during division. Being the key regulators of membrane dynamics, the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases, such as cancer and Alzheimer's disease. Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation. This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.

FUNDC2 promotes liver tumorigenesis by inhibiting MFN1-mediated mitochondrial fusion

Mitochondria generate ATP and play regulatory roles in various cellular activities. Cancer cells often exhibit fragmented mitochondria. However, the underlying mechanism remains elusive. Here we report that a mitochondrial protein FUN14 domain containing 2 (FUNDC2) is transcriptionally upregulated in primary mouse liver tumors, and in approximately 40% of human hepatocellular carcinoma (HCC). Importantly, elevated FUNDC2 expression inversely correlates with patient survival, and its knockdown inhibits liver tumorigenesis in mice. Mechanistically, the amino-terminal region of FUNDC2 interacts with the GTPase domain of mitofusin 1 (MFN1), thus inhibits its activity in promoting fusion of outer mitochondrial membrane. As a result, loss of FUNDC2 leads to mitochondrial elongation, decreased mitochondrial respiration, and reprogrammed cellular metabolism. These results identified a mechanism of mitochondrial fragmentation in cancer through MFN1 inhibition by FUNDC2, and suggested FUNDC2 as a potential therapeutic target of HCC.

Fragmented mitochondria are a frequent hallmark of cancer, but the cause and consequence are less clear. The authors demonstrate that elevated FUNDC2 causes mitochondrial fragmentation through inhibition of MFN1 in hepatocellular carcinoma and that knockdown of FUNDC2 inhibits liver tumorigenesis in mice.

Structure Elucidation and Anti-Tumor Activities of Trichothecenes from Endophytic Fungus Fusariumsporotrichioides

The secondary metabolites of Fusarium sporotrichioides, an endophytic fungus with anti-tumor activity isolated from Rauvolfia yunnanensis Tsiang, were investigated. Five trichothecenes, including one previously undescribed metabolite, were isolated and identified. Their structures were elucidated by means of extensive spectroscopic methods; the absolute configuration of compound 1 was determined by the ECD method. Surprisingly, 8-n-butyrylneosolaniol (3) exhibited stronger anti-tumor activity than T-2 toxin against Huh-7 cell line, with an IC₅₀ value of 265.9 nM. 8-n-butyrylneosolaniol (3) promoted apoptosis induction in Huh-7 cells. Moreover, cell cycle analysis showed that cell cycle arrest caused by 8-n-butyrylneosolaniol (3) at the G2/M phase resulted in cell proliferation inhibition and pro-apoptotic activity. Further studies showed a significant decrease in mitochondrial membrane permeabilization and a significant increase in ROS generation, which led to the activation of caspase cascades and subsequent cleavage of PARP fragments. In conclusion, 8-n-butyrylneosolaniol (3) induced cell apoptosis in Huh-7 cells via the mitochondria-mediated apoptotic signaling pathway, which could be a leading compound for anti-tumor agents.

Melatonin: A mitochondrial resident with a diverse skill set

Melatonin is an ancient molecule that originated in bacteria. When these prokaryotes were phagocytized by early eukaryotes, they eventually developed into mitochondria and chloroplasts. These new organelles retained the melatonin synthetic capacity of their forerunners such that all present-day animal and plant cells may produce melatonin in their mitochondria and chloroplasts. Melatonin concentrations are higher in mitochondria than in other subcellular compartments. Isolated mouse oocyte mitochondria form melatonin when they are incubated with serotonin, a necessary precursor. Oocyte mitochondria subsequently give rise to these organelles in all adult vertebrate cells where they continue to synthesize melatonin. The enzymes that convert serotonin to melatonin, i.e., arylalkylamine-N-acetyltransferase (AANAT) and acetylserotonin-O-methyltransferase, have been identified in brain mitochondria which, when incubated with serotonin, also form melatonin. Melatonin is a potent antioxidant and anti-cancer agent and is optimally positioned in mitochondria to aid in the maintenance of oxidative homeostasis and to reduce cancer cell transformation. Melatonin stimulates the transfer of mitochondria from healthy cells to damaged cells via tunneling nanotubes. Melatonin also regulates the major NAD⁺-dependent deacetylase, sirtuin 3, in the mitochondria. Disruptions of mitochondrial melatonin synthesis may contribute to a number of mitochondria-related diseases, as discussed in this review.

Mitochondrial Dysfunction and Acute Fatty Liver of Pregnancy

The liver is one of the richest organs in mitochondria, serving as a hub for key metabolic pathways such as β-oxidation, the tricarboxylic acid (TCA) cycle, ketogenesis, respiratory activity, and adenosine triphosphate (ATP) synthesis, all of which provide metabolic energy for the entire body. Mitochondrial dysfunction has been linked to subcellular organelle dysfunction in liver diseases, particularly fatty liver disease. Acute fatty liver of pregnancy (AFLP) is a life-threatening liver disorder unique to pregnancy, which can result in serious maternal and fetal complications, including death. Pregnant mothers with this disease require early detection, prompt delivery, and supportive maternal care. AFLP was considered a mysterious illness and though its pathogenesis has not been fully elucidated, molecular research over the past two decades has linked AFLP to mitochondrial dysfunction and defects in fetal fatty-acid oxidation (FAO). Due to deficient placental and fetal FAO, harmful 3-hydroxy fatty acid metabolites accumulate in the maternal circulation, causing oxidative stress and microvesicular fatty infiltration of the liver, resulting in AFLP. In this review, we provide an overview of AFLP and mitochondrial FAO followed by discussion of how altered mitochondrial function plays an important role in the pathogenesis of AFLP.