Mitochondrial Cyclosporine A-Independent Palmitate/Ca2+-Induced Permeability Transition Pore (PA-mPT Pore) and Its Role in Mitochondrial Function and Protection against Calcium Overload and Glutamate Toxicity

Mitochondrial homeostasis in odontoblast: Physiology, pathogenesis and targeting strategies

Caries and pulpitis remain a major global disease burden and affect the quality of life of patients. Odontoblasts are key players in the progression of caries and pulpitis, not only secreting and mineralizing to form dentin, but also acting as a wall of defense to initiate immune defenses. Mitochondrion is an information processor for numerous cellular activities, and dysregulation of mitochondrion homeostasis not only affects cellular metabolism but also triggers a wide range of diseases. Elucidating mitochondrial homeostasis in odontoblasts can help deepen scholars' understanding of odontoblast-associated diseases. Articles on mitochondrial homeostasis in odontoblasts were evaluated for information pertinent to include in this narrative review. This narrative review focused on understanding the complex interplay between mitochondrial homeostasis in odontoblasts under physiological and pathological conditions. Furthermore, mitochondria-centered therapeutic strategies (including mitochondrial base editing, targeting platforms, and mitochondrial transplantation) were emphasized by resolving key genes that regulate mitochondrial function. Mitochondria are involved in odontoblast differentiation and function, and act as mitochondrial danger-associated molecular patterns (mtDAMPs) to mediate odontoblast pathological progression. Novel mitochondria-centered therapeutic strategies are particularly attractive as emerging therapeutic approaches for the maintenance of mitochondrial homeostasis. It is expected to probe key events of odontoblast differentiation and advance the clinical resolution of dentin formation and mineralization disorders and odontoblast-related diseases.

Design, synthesis and mechanism study of coumarin-sulfonamide derivatives as carbonic anhydrase IX inhibitors with anticancer activity

In this study, twenty-nine coumarin-3-sulfonamide derivatives, twenty-seven of which are original were designed and synthesized. Cytotoxicity assay indicated that most of these derivatives exhibited moderated to good potency against A549 cells. Among them, compound 8q showed potent inhibition against the four tested cancer cell lines, especially A549 cells with IC50 value of 6.01 ± 0.81 μM, and much lower cytotoxicity on the normal cells was observed compared to the reference compounds. Bioinformatics analysis revealed human carbonic anhydrase IX (CAIX) was highly expressed in lung adenocarcinoma (LUAD) and associated with poor prognosis. The inhibitory activity of compound 8q against CAIX was assessed by using molecular docking and molecular dynamics simulations, which revealed prominent interactions of both compound 8q and CAIX at the active site and their high affinity. The results of ELISA assays verified that compound 8q possessed strong inhibitory activity against CAIX and high subtype selectivity, and could also down-regulate the expression of CAIX in A549 cells. Furthermore, the significant inhibitory effects of compound 8q on the migration and invasion of A549 cells were also found. After treatment with compound 8q, intracellular reactive oxygen species (ROS) levels increased and mitochondrial membrane potential (MMP) decreased. Mechanistic investigation using western blotting revealed compound 8q exerted the anti-migrative and anti-invasive effects probably through mitochondria-mediated PI3K/AKT pathway by targeting CAIX. In summary, coumarin-3-sulfonamide derivatives were developed as potential and effective CAIX inhibitors, which were worthy of further investigation.

Refractive Index Imaging Reveals That Elimination of the ATP Synthase C Subunit Does Not Prevent the Adenine Nucleotide Translocase-Dependent Mitochondrial Permeability Transition

The mitochondrial permeability transition pore (mPTP) is a large, weakly selective pore that opens in the mitochondrial inner membrane in response to the pathological increase in matrix Ca2+ concentration. mPTP activation has been implicated as a key factor contributing to stress-induced necrotic and apoptotic cell death. The molecular identity of the mPTP is not completely understood. Both ATP synthase and adenine nucleotide translocase (ANT) have been described as important components of the mPTP. Using a refractive index (RI) imaging approach, we recently demonstrated that the removal of either ATP synthase or ANT eliminates the Ca2+-induced mPTP in experiments with intact cells. These results suggest that mPTP formation relies on the interaction between ATP synthase and ANT protein complexes. To gain further insight into this process, we used RI imaging to investigate mPTP properties in cells with a genetically eliminated C subunit of ATP synthase. These cells also lack ATP6, ATP8, 6.8PL subunits and DAPIT but, importantly, have a vestigial ATP synthase complex with assembled F1 and peripheral stalk domains. We found that these cells can still undergo mPTP activation, which can be blocked by the ANT inhibitor bongkrekic acid. These results suggest that ANT can form the pore independently from the C subunit but still requires the presence of other components of ATP synthase.

The histone deacetylase inhibitor SAHA exerts a protective effect against myocardial ischemia/reperfusion injury by inhibiting sodium-calcium exchanger

Calcium overload performs a crucial function in the pathogenesis of myocardial ischemia-reperfusion (I/R) damage, which contributes to mitochondrial impairment and apoptosis of cardiomyocytes. Suberoylanilide hydroxamic acid (SAHA), a small molecule histone deacetylases inhibitor with modulatory capacity on Na⁺-Ca²⁺ exchanger (NCX), is proven to have protective potential towards cardiac remodeling and injury, but the mechanism remains unclear. Hence, Hence, our present research explored the modulation of NCX-Ca²⁺-CaMKII by SAHA in myocardial I/R damage. Our outcomes indicate that in vitro hypoxia and reoxygenation models of myocardial cells, SAHA treatment inhibited the increase in expression of NCX1, intracellular Ca²⁺ concentration, expression of CaMKII and self-phosphorylated CaMKII, and cell apoptosis. In addition, SAHA treatment improved myocardial cell mitochondrial swelling inhibited mitochondrial membrane potential diminution and the openness of the mitochondrial permeability transition pore, and protected against mitochondrial dysfunction following I/R injury. In vivo, SAHA treatment alleviated the decrease in FS% and EF%, the increase in the myocardial infarct area, and myocardial enzyme levels caused by I/R injury, while also reducing myocardial cell apoptosis, and inhibiting mitochondrial fission and mitochondrial membrane rupture. These results indicated that SAHA treatment alleviated myocardial cell apoptosis as well as mitochondrial dysfunction resulting from myocardial I/R impairment, and contributed to myocardial function recovery by inhibiting the NCX-Ca²⁺-CaMKII pathway. These findings offered additional theoretical support to explore the mechanism of SAHA as a therapeutic agent in cardiac I/R damage and develop new treatment strategies.

Bile Acids as Inducers of Protonophore and Ionophore Permeability of Biological and Artificial Membranes

It is now generally accepted that the role of bile acids in the organism is not limited to their participation in the process of food digestion. Indeed, bile acids are signaling molecules and being amphiphilic compounds, are also capable of modifying the properties of cell membranes and their organelles. This review is devoted to the analysis of data on the interaction of bile acids with biological and artificial membranes, in particular, their protonophore and ionophore effects. The effects of bile acids were analyzed depending on their physicochemical properties: namely the structure of their molecules, indicators of the hydrophobic-hydrophilic balance, and the critical micelle concentration. Particular attention is paid to the interaction of bile acids with the powerhouse of cells, the mitochondria. It is of note that bile acids, in addition to their protonophore and ionophore actions, can also induce Ca²⁺-dependent nonspecific permeability of the inner mitochondrial membrane. We consider the unique action of ursodeoxycholic acid as an inducer of potassium conductivity of the inner mitochondrial membrane. We also discuss a possible relationship between this K⁺ ionophore action of ursodeoxycholic acid and its therapeutic effects.

Endoplasmic Reticulum Stress and Mitochondrial Stress in Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a widespread and harmful disease closely linked to mitochondrial and endoplasmic reticulum stress (ERS). Globally, severe drug-induced hepatitis, cirrhosis, and liver cancer are the primary causes of liver-related morbidity and mortality. A hallmark of DILI is ERS and changes in mitochondrial morphology and function, which increase the production of reactive oxygen species (ROS) in a vicious cycle of mutually reinforcing stress responses. Several pathways are maladapted to maintain homeostasis during DILI. Here, we discuss the processes of liver injury caused by several types of drugs that induce hepatocyte stress, focusing primarily on DILI by ERS and mitochondrial stress. Importantly, both ERS and mitochondrial stress are mediated by the overproduction of ROS, destruction of Ca2+ homeostasis, and unfolded protein response (UPR). Additionally, we review new pathways and potential pharmacological targets for DILI to highlight new possibilities for DILI treatment and mitigation.

LACTB induces cancer cell death through the activation of the intrinsic caspase-independent pathway in breast cancer

BACKGROUND

LACTB was recently identified as a mitochondrial tumour suppressor that negatively affects cancer cell proliferation by inducing cell death and/or differentiation, depending on the cell type and tissue. However, the detailed mechanism underlying the LACTB-induced cancer cell death is largely unknown.

METHODS

We used cell-based, either in 2D or 3D conditions, and in vivo experiments to understand the LACTB mechanisms. In this regard, protein array followed by an enrichment analysis, cell proliferation assays using different compounds, western blot analysis, flow cytometry and immunofluorescence were performed. Differences between quantitative variables following normal distribution were valuated using Student t test for paired or no-paired samples according to the experiment. For in vivo experiments differences in tumour growth were analyzed by 2-way ANOVA.

RESULTS

We show, that LACTB expression leads to cell cycle arrest in G1 phase and increase of DNA oxidation that leads to activation of intrinsic caspase-independent cell death pathway. This is achieved by an increase of mitochondrial reactive oxygen species since early time points of LACTB induction.

CONCLUSION

Our work provides a deeper mechanistic insight into LACTB-mediated cancer-cell death and shows the dynamics of the cellular responses a particular tumor suppressive stimulus might evoke under different genetic landscapes.

Mitochondrial Permeability Transition

The mitochondrial permeability transition (PT) is a phenomenon that can be broadly defined as an increase in the permeability of the mitochondrial inner membrane [...].

What is responsible for acute myocardial infarction in combination with aplastic anemia? A case report and literature review

BACKGROUND

Aplastic anemia (AA) complicated with myocardial infarction (MI) is rare and associated with poor prognosis. Here, we present a case of AA with recurrent acute MI (AMI) in a patient treated with cyclosporine A (CsA) and stanozolol. In this patient, we suspect the long-term use of medication linked to platelets hyperfunction.

CASE SUMMARY

In 2017, a 45-year-old man was rushed to the emergency department of China-Japan Union Hospital due to precordial pain for 5 h. Based on his symptoms, medical history, blood tests, and findings from coronary angiography (CAG), the patient was diagnosed with acute anterior wall, ST-segment elevated MI, Killip II grade, AA, and dyslipidemia. In 2021, the patient was readmitted to the hospital for 2 h due to chest pain. Because the patient’s platelet count was 30 × 10⁹/L and he had severe thrombocytopenia, we performed CAG following platelet transfusion. Optical coherence tomography revealed lipid plaque and thrombus mass in his right coronary artery. The antithrombotic approach was adjusted to employ only anticoagulants (factor Xa inhibitors) and adenosine diphosphate inhibitors (clopidogrel) after assessing the risk of bleeding/thrombotic events. Long-term follow-up revealed that the patient had made a good recovery.

CONCLUSION

Patients with AA should be closely monitored for the risk of thrombosis and cardiovascular events, particularly when taking stanozolol or CsA for an extended period of time.

Involvement of oxidative species in cyclosporine-mediated cholestasis

Cyclosporine is an established medication for the prevention of transplant rejection. However, adverse consequences such as nephrotoxicity, hepatotoxicity, and cholestasis have been associated with prolonged usage. In cyclosporine-induced obstructive and chronic cholestasis, for example, the overproduction of oxidative stress is significantly increased. Additionally, cyclosporine exerts adverse effects on liver function and redox balance responses in treated rats, as evidenced by its increasing levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin while also decreasing the levels of glutathione and NADPH. Cyclosporine binds to cyclophilin to produce its therapeutic effects, and the resulting complex inhibits calcineurin, causing calcium to accumulate in the mitochondria. Accumulating calcium with concomitant mitochondrial abnormalities induces oxidative stress, perturbation in ATP balance, and failure of calcium pumps. Also, cyclosporine-induced phagocyte oxidative stress generation via the interaction of phagocytes with Toll-like receptor-4 has been studied. The adverse effect of cyclosporine may be amplified by the release of mitochondrial DNA, mediated by oxidative stress-induced mitochondrial damage. Given the uncertainty surrounding the mechanism of cyclosporine-induced oxidative stress in cholestasis, we aim to illuminate the involvement of oxidative stress in cyclosporine-mediated cholestasis and also explore possible strategic interventions that may be applied in the future.

The Short-Term Opening of Cyclosporin A-Independent Palmitate/Sr2+-Induced Pore Can Underlie Ion Efflux in the Oscillatory Mode of Functioning of Rat Liver Mitochondria

Mitochondria are capable of synchronized oscillations in many variables, but the underlying mechanisms are still unclear. In this study, we demonstrated that rat liver mitochondria, when exposed to a pulse of Sr2+ ions in the presence of valinomycin (a potassium ionophore) and cyclosporin A (a specific inhibitor of the permeability transition pore complex) under hypotonia, showed prolonged oscillations in K+ and Sr2+ fluxes, membrane potential, pH, matrix volume, rates of oxygen consumption and H2O2 formation. The dynamic changes in the rate of H2O2 production were in a reciprocal relationship with the respiration rate and in a direct relationship with the mitochondrial membrane potential and other indicators studied. The pre-incubation of mitochondria with Ca2+(Sr2+)-dependent phospholipase A2 inhibitors considerably suppressed the accumulation of free fatty acids, including palmitic and stearic acids, and all spontaneous Sr2+-induced cyclic changes. These data suggest that the mechanism of ion efflux from mitochondria is related to the opening of short-living pores, which can be caused by the formation of complexes between Sr2+(Ca2+) and endogenous long-chain saturated fatty acids (mainly, palmitic acid) that accumulate due to the activation of phospholipase A2 by the ions. A possible role for transient palmitate/Ca2+(Sr2+)-induced pores in the maintenance of ion homeostasis and the prevention of calcium overload in mitochondria under pathophysiological conditions is discussed.

Mitochondrial function in spinal cord injury and regeneration

Many people around the world suffer from some form of paralysis caused by spinal cord injury (SCI), which has an impact on quality and life expectancy. The spinal cord is part of the central nervous system (CNS), which in mammals is unable to regenerate, and to date, there is a lack of full functional recovery therapies for SCI. These injuries start with a rapid and mechanical insult, followed by a secondary phase leading progressively to greater damage. This secondary phase can be potentially modifiable through targeted therapies. The growing literature, derived from mammalian and regenerative model studies, supports a leading role for mitochondria in every cellular response after SCI: mitochondrial dysfunction is the common event of different triggers leading to cell death, cellular metabolism regulates the immune response, mitochondrial number and localization correlate with axon regenerative capacity, while mitochondrial abundance and substrate utilization regulate neural stem progenitor cells self-renewal and differentiation. Herein, we present a comprehensive review of the cellular responses during the secondary phase of SCI, the mitochondrial contribution to each of them, as well as evidence of mitochondrial involvement in spinal cord regeneration, suggesting that a more in-depth study of mitochondrial function and regulation is needed to identify potential targets for SCI therapeutic intervention.

S-15176 Difumarate Salt Can Impair Mitochondrial Function through Inhibition of the Respiratory Complex III and Permeabilization of the Inner Mitochondrial Membrane

S-15176 difumarate salt, a derivative of the anti-ischemic metabolic drug trimetazidine, has been intensively studied for its impact on cellular metabolism in animal models of ischemia-reperfusion injury of the liver, heart, spinal cord, and other organs. Despite evidence of some reduction in oxidative damage to cells, the results of therapy with S-15176 have been mostly disappointing, possibly because of the lack of data on its underlying mechanisms. Here, we aimed to investigate in more detail the role of complexes I-IV of the electron transport chain and membrane permeability transition in mitochondrial toxicity associated with S-15176. Using rat thymocyte and liver mitochondria, we demonstrated that: (1) acute exposure to S-15176 (10 to 50 μM) dose-dependently decreased the mitochondrial membrane potential; (2) S-15176 suppressed the ADP-stimulated (State 3) and uncoupled (State 3UDNP) respiration of mitochondria energized with succinate or malate/glutamate, but not ascorbate/TMPD, and increased the resting respiration (State 4) when using all the substrate combinations; (3) S-15176 directly inhibited the activity of the respiratory complex III; (4) low doses of S-15176 diminished the rate of H2O2 production by mitochondria; (5) at concentrations of above 30 μM, S-15176 reduced calcium retention capacity and contributed to mitochondrial membrane permeabilization. Taken together, these findings suggest that S-15176 at tissue concentrations reached in animals can impair mitochondrial function through suppression of the cytochrome bc1 complex and an increase in the nonspecific membrane permeability.