The multiple functions of cytochrome c and their regulation in life and death decisions of the mammalian cell: From respiration to apoptosis

Myocardial transcriptomic and proteomic landscapes across the menopausal continuum in a murine model of chemically induced accelerated ovarian failure

Risk of cardiovascular disease (CVD) in women increases with the menopausal transition. Using a chemical model (4-vinylcyclohexene diepoxide; VCD) of accelerated ovarian failure, we previously demonstrated that menopausal females are more susceptible to CVD compared with peri- or premenopausal females like humans. Yet, the cellular and molecular mechanisms underlying this shift in CVD susceptibility across the pre- to peri- to menopause continuum remain understudied. In this work using the VCD mouse model, we phenotyped cellular and molecular signatures from hearts at each hormonally distinct stage that included transcriptomic, proteomic, and cell biological analyses. The transcriptional profile of premenopausal hearts clustered separately from perimenopausal and menopausal hearts, which clustered more similarly. Proteomics also revealed hormonal clustering; perimenopausal hearts grouped more closely with premenopausal than menopausal hearts. Both proteomes and transcriptomes showed similar trends in genes associated with atherothrombosis, contractility, and impaired nuclear signaling between pre-, peri-, and menopausal murine hearts. Further analysis of posttranslational modifications (PTMs) showed hormone-dependent shifts in the phosphoproteome and acetylome. To further interrogate these findings, we triggered pathological remodeling using angiotensin II (Ang II). Phosphorylation of AMP-activated protein kinase (AMPK) signaling and histone deacetylase (HDAC) activity were found to be dependent on hormonal status and Ang II stimulation. Finally, knockdown of anti-inflammatory regulatory T cells (Treg) exacerbated Ang II-dependent fibrosis implicating HDAC-mediated epigenetic suppression of Treg activity. Taken together, we demonstrated unique cellular and molecular profiles underlying the cardiac phenotype of pre-, peri-, and menopausal mice supporting the necessity to study CVD in females across the hormonal transition.NEW & NOTEWORTHY Cycling and perimenopausal females are protected from cardiovascular disease (CVD) whereas menopausal females are more susceptible to CVD and other pathological sequalae. The cellular and molecular mechanisms underlying loss of CVD protection across the pre- to peri- to menopause transition remain understudied. Using the murine 4-vinylcyclohexene diepoxide (VCD) model of menopause we highlight cellular and molecular signatures from hearts at each hormonally distinct stage that included transcriptomic, proteomic, and cell biological analyses.

An integrative analysis combining bioinformatics, network pharmacology and experimental methods identified key genes of EGCG targets in Nasopharyngeal Carcinoma

BACKGROUND

Epigallocatechin gallate (EGCG), a frequently studied catechin in green tea, has been shown to be involved in the antiproliferation and apoptosis of human Nasopharyngeal carcinoma (NPC) cells. However, the pharmacological targets and mechanism by which EGCG can combat NPC patients remain to be studied in detail.

METHODS

Network pharmacology and bioinformatics were employed to investigate the molecular mechanisms underlying EGCG's therapeutic effects on NPC, with an emphasis on developing a prognostic risk model and identifying potential therapeutic targets.

RESULTS

A novel prognostic risk model was developed using univariate Cox regression, LASSO regression and multivariable Cox regression analyses, incorporating six genes to stratify patients into low- and highrisk groups. Kaplan-Meier analysis demonstrated significantly shorter progression-free survival in the high-risk group. The model's accuracy was further validated using time-dependent Receiver Operating Characteristic (ROC) curves. ESTIMATE analysis revealed significantly higher immune, stromal and overall ESTIMATE scores in the low-risk group compared to the high-risk group. Immune profiling indicated significant differences in five immune cell subtypes (memory B cells, regulatory T cells (Tregs), gamma delta T cells, activated NK cells and activated dendritic cells) between the two risk groups. Additionally, the low-risk group showed greater sensitivity to conventional chemotherapeutic agents. Immunohistochemistry and molecular docking analyses identified CYCS and MYL12B as promising targets for EGCG treatment.

CONCLUSION

This study utilised network pharmacology and bioinformatics to identify shared genes between EGCG and NPC, aiming to elucidate the molecular mechanisms through which EGCG inhibits NPC and to develop a prognostic model for assessing patient outcomes. The findings provide potential insights for the development of anti-NPC therapies and their clinical applications.

Tracking heme biology with resonance Raman spectroscopy

Heme proteins are a large group of biomolecules with heme incorporated as a prosthetic group. Apart from cytochromes present in almost all cell types, many other specific heme proteins are expressed in different kinds of cells, e.g. hemoglobin in the erythrocytes, myoglobin (skeletal and vascular smooth muscle cells), cytoglobin (fibroblasts) and neuroglobin (neurons and retina). Among their wide and diverse biological functions, the most important is their unique ability to bind, store, and transport gaseous molecules, such as oxygen, carbon monoxide, and nitric oxide. Resonance Raman (RR) spectroscopy is an exceptional analytical tool that allows for qualitative and quantitative characterization of heme proteins in biological systems. Due to its high sensitivity, even subtle structural alterations of the heme group can be monitored and tracked during cellular processes. Resonance Raman excitation within the Soret absorption band (390-440 nm) provides rich information on the environment of heme's active site, allowing differentiation of the iron ion oxidation and spin states, and tracking the movement of the porphyrin ring plane in response to the changes in oxygenation status. Herein, we summarize and discuss recent developments in RR applications aimed to link the structure-function relationship of heme proteins within biological systems, connected, e.g., with the formation of hemoglobin (Hb) adducts (nitrosylhemoglobin, cyanhemoglobin, sulfhemoglobin), irreversible Hb alterations deteriorating oxygen binding and differentiation of heme proteins oxidation state within live cells in situ.

A computational study of the fold and stability of cytochrome c with implications for disease

Cytochrome c (Cyt-c), encoded by the CYCS gene, is crucial for electron transport, peroxidase activity, and apoptosis. Mutations in CYCS cause thrombocytopenia 4 (THC4), a disorder with low platelet counts. We have, for instance, recently described six Italian families with five different heterozygous missense CYCS variants. These mutations likely enhance peroxidase and apoptotic activities, yet the mechanisms causing reduced platelet production and increased apoptosis are unclear. This study investigates clinically-related Cyt-c variants using an integrated bioinformatics approach. Our findings reveal that all variants are at evolutionarily conserved sites, potentially disrupting Cyt-c function and contributing to disease phenotypes. Specific variants are predicted to affect phosphorylation (T20I, V21G, Y49H), and ubiquitination (G42S, A52T, A52V, T103I). Molecular dynamics simulations (500 ns) revealed significant structural deviations from the wild-type protein, with mutants showing reduced stability and increased unfolding and flexibility, particularly in the Ω-loops. These changes result in the displacement of the Ω-loops away from the heme iron, weakening critical hydrogen bonds and consequently opening the heme active site. This open conformation may enhance accessibility to small molecules such as H₂O₂, thereby promoting peroxidase activity, which may enhance apoptosis and likely impact megakaryopoiesis and platelet homeostasis in THC4.

Insights on using plastic-based dual in-plane nanopore sensors for differentiation and shape determinations of single protein molecules

Techniques to analyze proteins often involves complex workflows and/or sophisticated equipment with modest limits-of-detection. While fluorescence spectroscopy can interrogate single molecules, it often requires fluorescence labeling with lasers and microscopes. We report herein a label-free approach for analyzing intact proteins using resistive pulse sensing (RPS). RPS data were secured using a unique RPS device, which we call a dual in-plane nanopore sensor, fabricated in a thermoplastic. The nanopore sensor was produced via nano-injection molding with critical structures of 30 nm, enabling the detection of individual protein molecules and providing an approach toward their identification. Following nano-injection molding, the pore size could be reduced to ∼ 10 nm using thermal fusion bonding of a cover plate to the molded substrate. The device architecture contained two in-plane nanopores flanking a nanochannel (50 × 50 nm width × depth and 5 µm length) that facilitated the measurement of the apparent electrophoretic mobilities of protein molecules in a label free manner via their molecular-dependent time-of-flight (ToF; time-difference between two consecutive RPS events-peak pair). We investigated four model proteins and collected multiple characteristics including RPS peak amplitude and dwell time, as well as an RPS-independent value, which was the ToF. Furthermore, we analyzed the temporal profiles of RPS events revealing distinct peak shapes for spherical and non-spherical proteins that were influenced by their rotational motion when resident within the nanopore.

Cytosolic cytochrome c represses ferroptosis

The release of cytochrome c, somatic (CYCS) from mitochondria to the cytosol is an established trigger of caspase-dependent apoptosis. Here, we unveil an unexpected role for cytosolic CYCS in inhibiting ferroptosis-a form of oxidative cell death driven by uncontrolled lipid peroxidation. Mass spectrometry and site-directed mutagenesis revealed the existence of a cytosolic complex composed of inositol polyphosphate-4-phosphatase type I A (INPP4A) and CYCS. This CYCS-INPP4A complex is distinct from the CYCS-apoptotic peptidase activating factor 1 (APAF1)-caspase-9 apoptosome formed during mitochondrial apoptosis. CYCS boosts INPP4A activity, leading to increased formation of phosphatidylinositol-3-phosphate, which prevents phospholipid peroxidation and plasma membrane rupture, thus averting ferroptotic cell death. Unbiased screening led to the identification of the small-molecule compound 10A3, which disrupts the CYCS-INPP4A interaction. 10A3 sensitized cultured cells and tumors implanted in immunocompetent mice to ferroptosis. Collectively, these findings redefine our understanding of cytosolic CYCS complexes that govern diverse cell death pathways.

Comparative analysis of cold-stored apheresis platelet units in additive solution with or without pathogen reduction: Implications of cytochrome c supplementation

BACKGROUND

Platelets are limited in supply, and the preservation of platelet function during storage remains challenging. Novel storage approaches are being explored to improve platelet quality, extend shelf life, and reduce risk of infection. This study sought to elucidate platelet function in cold-stored apheresis units in additive solution (platelet additive solution [PAS]) and subjected to pathogen reduction (PR) as well as the impact of cytochrome c (cyt c) supplementation. We hypothesized that the PR would decrease stored platelet function, regardless of cyt c supplementation.

METHODS

Platelet apheresis units (PAS) were collected (N = 5 volunteers) and divided into PR or no PR (PAS) and supplemented with vehicle or cyt c (100 μM). Units were stored at 4°C for 15 days, sequential aliquots were removed, and platelet/mitochondrial respiratory function and biochemical parameters were analyzed.

RESULTS

There was no difference in platelet aggregation in response to adenosine diphosphate between PAS and PR platelets. Aggregation function in response to arachidonic acid was higher in PR versus PAS platelets. Maximum clot strength was not different between PAS and PR from Day 0 to Day 5 but declined in PR platelets on Days 10 and 15. Oxygen consumption declined at the same rate in PAS and PR platelets, while rate of lactate and TCO 2 decrease was greater in PR platelets than in PAS platelets. Supplementation with cyt c did not alter platelet function or biochemical parameters in PAS or PR platelets.

CONCLUSION

Platelet additive solution and PR platelets show similar declines in respiratory capacity, and biochemical parameters during cold storage, but PR platelets demonstrated significantly increased arachidonic acid-induced aggregation across all time points. Further understanding this mechanism may provide a means to prolong platelet shelf life.

Heat stress: a major threat to ruminant reproduction and mitigating strategies

Stress is an external event or condition that puts pressure on a biological system. Heat stress is defined as the combination of internal and external factors acting on an animal to cause an increase in body temperature and elicit a physiological response. Heat stress is a set of conditions caused by overexposure to or overexertion at excess ambient temperature and leads to the inability of animals to dissipate enough heat to sustain homeostasis. Heat exhaustion, heat stroke, and cramps are among the symptoms. For the majority of mammalian species, including ruminants, heat stress has a negative impact on physiological, reproductive, and nutritional requirements. Reproductive functions, including the male and female reproductive systems, are negatively affected by heat stress. It decreases libido and spermatogenic activity in males and negatively affects follicle development, oogenesis, oocyte maturation, fertilization, implantation, and embryo-fetal development in females. These effects lead to a decrease in the rate of reproduction and financial losses for the livestock industry. Understanding the impact of heat stress on reproductive tissues will aid in the development of strategies for preventing heat stress and improving reproductive functions. Modification of the microenvironment, nutritional control, genetic development of heat-tolerant breeds, hormonal treatment, estrous synchronization, timed artificial insemination, and embryo transfer are among the strategies used to reduce the detrimental effects of heat stress on reproduction. These strategies may also increase the likelihood of establishing pregnancy in farm animals.

Lighting the Path: Raman Spectroscopy's Journey Through the Microbial Maze

The rapid and precise identification of microorganisms is essential in environmental science, pharmaceuticals, food safety, and medical diagnostics. Raman spectroscopy, valued for its ability to provide detailed chemical and structural information, has gained significant traction in these fields, especially with the adoption of various excitation wavelengths and tailored optical setups. The choice of wavelength and setup in Raman spectroscopy is influenced by factors such as applicability, cost, and whether bulk or single-cell analysis is performed, each impacting sensitivity and specificity in bacterial detection. In this study, we investigate the potential of different excitation wavelengths for bacterial identification, utilizing a mock culture composed of six bacterial species: three Gram-positive (S. warneri, S. cohnii, and E. malodoratus) and three Gram-negative (P. stutzeri, K. terrigena, and E. coli). To improve bacterial classification, we applied machine learning models to analyze and extract unique spectral features from Raman data. The results indicate that the choice of excitation wavelength significantly influences the bacterial spectra obtained, thereby impacting the accuracy and effectiveness of the subsequent classification results.

Cytochrome c and cancer cell metabolism: A new perspective

Cytochrome c is a vital electron carrier in the mitochondrial respiratory chain. When the outer membrane of mitochondria becomes permeable, cytochrome c is discharged into the cytoplasm, where it initiates the intrinsic apoptosis pathway. The complex interaction between cytochrome c and apoptosis protease-activating factor-1 (Apaf-1) leads to the formation of the apoptosome and activation of a cascade of caspases, highlighting the critical role of cytochrome c in controlling cell death mechanisms. Additionally, cytochrome c undergoes post-translational modifications, especially phosphorylation, which intricately regulate its roles in both respiration and apoptosis. These modifications add layers of complexity to how cytochrome c effectively controls cellular functions. cytochrome c becomes a lighthouse in the intricate web of cancer, its expression patterns providing hints about prognosis and paths toward treatment. Reduced levels of cytochrome c have been observed in cancer tissues, indicating a potential inhibition of apoptosis. For instance, in glioma tissues, cytochrome c levels were lower compared to healthy tissues, and this reduction became more pronounced in advanced stages of the disease. However, the role of cytochrome c in cancer becomes more intricate as it becomes intertwined with the metabolic reprogramming of cancer cells. This suggests that cytochrome c plays a crucial role in tumor progression and resistance to treatment. Viewing cytochrome c as a molecular mosaic reveals that it is not merely a protein, but also a central player in determining cellular fate. This realization opens up exciting avenues for potential advancements in cancer diagnosis and treatment strategies. Despite the advancements made, the narrative surrounding cytochrome c remains incomplete, urging further exploration into its complexities and the biological implications linked to cancer. cytochrome c stands as a beacon of hope and a promising target for therapy in the battle against cancer, particularly due to its significant involvement in tumor metabolism. It holds the potential for a future where innovative solutions can be developed to address the intricate challenges of cellular fate. In this review, we have endeavored to illuminate the multifaceted domain of cytochrome c drawing connections among apoptosis, metabolic reprogramming, and the Warburg effect in the context of cancer.

New findings on post-mortem chicken quality changes: The ROS-influenced MAPK-JNK signaling pathway affects chicken quality by regulating muscle cell apoptosis

Research conducted previously has demonstrated that apoptosis significantly influences the chicken quality. While ROS are acknowledged as significant activators of apoptosis, the precise mechanism by which they influence muscle cell apoptosis in the post-mortem remains unclear. In this study, chicken samples were treated with rosemarinic acid and H2O2 to induce varying ROS levels, and the ROS-triggered apoptosis mechanism in chicken muscle cells in post-mortem was analyzed. The TUNEL results revealed that elevated ROS levels in chicken were associated with a greater degree of muscle cell apoptosis. Western-blot results suggested that sarcoplasmic ROS could initiate apoptosis through the mitochondrial pathway by activating the MAPK-JNK signaling pathway. Moreover, TEM and shear force results demonstrated that muscle cell apoptosis initiates myofiber fragmentation and structural damage to sarcomeres, ultimately reducing chicken tenderness. This study enhances our understanding of post-mortem muscle cell apoptosis, providing valuable insights for regulating chicken quality.

An In Vitro Strategy to Evaluate Ketoprofen Phototoxicity at the Molecular and Cellular Levels

Phototoxicity is a significant problem that occurs in a large part of the population and is often caused by commonly used pharmaceuticals, including over-the-counter drugs. Therefore, testing drugs with photosensitizing potential is very important. The aim of this study is to analyze the cytotoxicity and phototoxicity of ketoprofen towards human melanocytes and fibroblasts in three different treatment schemes in order to optimize the study. Cytometric tests (studies of viability, proliferation, intracellular thiol levels, mitochondrial potential, cell cycle, and DNA fragmentation), Western blot analysis (cytochrome c and p44/p42 protein levels), and confocal microscopy imaging were performed to assess the impact of the developed treatments on skin cells. Research on experimental schemes may help reduce or eliminate the risk of phototoxic reactions. In the case of ketoprofen, we found that the strongest phototoxic potential was exhibited in the treatment where the drug was present in the solution during the irradiation of cells, both pigmented and non-pigmented cells. These results indicate that the greatest risk of photosensitivity reactions related to ketoprofen occurs after direct contact with the drug and UV exposure.

DAZAP1 Phase Separation Regulates Mitochondrial Metabolism to Facilitate Invasion and Metastasis of Oral Squamous Cell Carcinoma

Tumor invasion and metastasis are the underlying causes of high mortality rate due to oral squamous cell carcinoma (OSCC). Energy metabolism reprogramming has been identified as a crucial process mediating tumor metastasis, thus indicating an urgent need for an in-depth investigation of the specific mechanisms of tumor energy metabolism. Here, we identified an RNA-binding protein, DAZ-associated protein 1 (DAZAP1), as a tumor-promoting factor with an important role in OSCC progression. DAZAP1 was significantly upregulated in OSCC, which enhanced the migration and invasion of OSCC cells and induced the epithelial-mesenchymal transition (EMT). RNA sequencing analysis and experimental validation demonstrated that DAZAP1 regulates mitochondrial energy metabolism in OSCC. Mechanistically, DAZAP1 underwent liquid-liquid phase separation to accumulate in the nucleus where it enhanced cytochrome c oxidase 16 (COX16) expression by regulating pre-mRNA alternative splicing, thereby promoting OSCC invasion and mitochondrial respiration. In mouse OSCC models, loss of DAZAP1 suppressed EMT, downregulated COX16, and reduced tumor growth and metastasis. In samples from patients with OSCC, expression of DAZAP1 positively correlated with COX16 and a high expression of both proteins was associated with poor patient prognosis. Together, these findings revealed a mechanism by which DAZAP1 supports mitochondrial metabolism and tumor development of OSCC, suggesting the potential of therapeutic strategies targeting DAZAP1 to block OSCC invasion and metastasis. Significance: The RNA-binding protein DAZAP1 undergoes phase separation to enhance COX16 expression and mediate metabolic reprogramming that enables tumor metastasis, highlighting DAZAP1 as a potential metabolic target for cancer therapy.

Progress and limitations in reactive oxygen species quantitation

Reactive oxygen species (ROS) are a set of oxygen- and nitrogen-containing radicals. They are produced from a wide range of sources. In biological contexts, cellular stress leads to an overproduction of ROS, which can lead to genetic damage and disease development. In industry, ROS are often productively used for water purification or for analyzing the possible toxicity of an industrial process. Because of their ubiquity, detection of ROS has been an analytical goal across a range of fields. To understand complicated systems and origins of ROS production, it is necessary to move from qualitative detection to quantitation. Analytical techniques that combine quantitation, high spatial and temporal resolution, and good specificity represent detection methods that can fill critical gaps in ROS research. Herein, we discuss the continued progress and limitations of fluorescence, electrochemical, and electron paramagnetic resonance detection of ROS over the last ten years, giving suggestions for the future of the field.

Therapeutic efficacy of Genistein in activation of neuronal AC/cAMP/CREB/PKA and mitochondrial ETC-Complex pathways in experimental model of autism: Evidence from CSF, blood plasma and brain analysis

Autism is a complex neurodevelopmental condition characterized by repetitive behaviors, impaired social communication, and various associated conditions such as depression and anxiety. Its multifactorial etiology includes genetic, environmental, dietary, and gastrointestinal contributions. Pathologically, Autism is linked to mitochondrial dysfunction, oxidative stress, neuroinflammation, and neurotransmitter imbalances involving GABA, glutamate, dopamine, and oxytocin. Propionic acid (PRPA) is a short-chain fatty acid produced by gut bacteria, influencing central nervous system functions. Elevated PRPA levels can exacerbate Autism-related symptoms by disrupting metabolic processes and crossing the blood-brain barrier. Our research investigates the neuroprotective potential of Genistein (GNT), an isoflavone compound with known benefits in neuropsychiatric and neurodegenerative disorders, through modulation of the AC/cAMP/CREB/PKA signaling pathway and mitochondrial ETC complex (I-IV) function. In silico analyses revealed GNT's high affinity for these targets. Subsequent in vitro and in vivo experiments using a PRPA-induced rat model of autism demonstrated that GNT (40 and 80 mg/kg., orally) significantly improves locomotion, neuromuscular coordination, and cognitive functions in PRPA-treated rodents. Behavioral assessments showed reduced immobility in the forced swim test, enhanced Morris water maze performance, and restored regular locomotor activity. On a molecular level, GNT restored levels of key signaling molecules (AC, cAMP, CREB, PKA) and mitochondrial complexes (I-V), disrupted by PRPA exposure. Additionally, GNT reduced neuroinflammation and apoptosis, normalized neurotransmitter levels, and improved the complete blood count profile. Histopathological analyses confirmed that GNT ameliorated PRPA-induced brain injuries, restored normal brain morphology, reduced demyelination, and promoted neurogenesis. The study supports GNT's potential in autism treatment by modulating neural pathways, reducing inflammation, and restoring neurotransmitter balance.

Probing the versatility of cytochrome c by spectroscopic means: A Laudatio on resonance Raman spectroscopy

Over the last 50 years resonance Raman spectroscopy has become an invaluable tool for the exploration of chromophores in biological macromolecules. Among them, heme proteins and metal complexes have attracted considerable attention. This interest results from the fact that resonance Raman spectroscopy probes the vibrational dynamics of these chromophores without direct interference from the surrounding. However, the indirect influence via through-bond and through-space chromophore-protein interactions can be conveniently probed and analyzed. This review article illustrates this point by focusing on class 1 cytochrome c, a comparatively simple heme protein generally known as electron carrier in mitochondria. The article demonstrates how through selective excitation of resonance Raman active modes information about the ligation, the redox state and the spin state of the heme iron can be obtained from band positions in the Raman spectra. The investigation of intensities and depolarization ratios emerged as tools for the analysis of in-plane and out-of-plane deformations of the heme macrocycle. The article further shows how resonance Raman spectroscopy was used to characterize partially unfolded states of oxidized cytochrome c. Finally, it describes its use for exploring structural changes due to the protein's binding to anionic surfaces like cardiolipin containing membranes.

Cytochrome c electrochemical detection utilizing molecularly imprinted poly(3, 4-ethylenedioxythiophene) on a disposable screen printed carbon electrode

Cytochrome c (cyt c) has been found to play a function in apoptosis in cell-free models. This work presents the creation of molecularly imprinted conducting poly(3, 4-ethylenedioxythiopene) (MIPEDOT) on the surface of a screen printed carbon electrode (SPCE) for cyt c. Cyt c was imprinted by electropolymerization due to the presence of an EDOT monomer hydrophobic functional group on SPCE, using CV to obtain highly selective materials with excellent molecular recognition ability. MIPEDOT was characterized by CV, EIS, and DPV using ferricyanide/ferrocyanide as a redox probe. Further, the characterization of the sensor was accomplished using SEM for surface morphological confirmation. Using CV, the peak current measured at the potential of +1 to -1 V (vs. Ag/AgCl) is linear in the cyt c concentration range from 1 to 1200 pM, showing a remarkably low detection limit of 0.5 pM (sensitivity:0.080 μA pM). Moreover, the applicability of the approach was successfully confirmed with the detection of cyt c in biological samples (human plasma). Similarly, our research has proven a low-cost, simple, and efficient sensing platform for cyt c detection, rendering it a viable tool for the future improvement of reliable and exact non-encroaching cell death detection.

A promising future of metal-N-heterocyclic carbene complexes in medicinal chemistry: The emerging bioorganometallic antitumor agents

Metal complexes based on N-heterocyclic carbene (NHC) ligands have emerged as promising broad-spectrum antitumor agents in bioorganometallic medicinal chemistry. In recent decades, studies on cytotoxic metal-NHC complexes have yielded numerous compounds exhibiting superior cytotoxicity compared to cisplatin. Although the molecular mechanisms of these anticancer complexes are not fully understood, some potential targets and modes of action have been identified. However, a comprehensive review of their biological mechanisms is currently absent. In general, apoptosis caused by metal-NHCs is common in tumor cells. They can cause a series of changes after entering cells, such as mitochondrial membrane potential (MMP) variation, reactive oxygen species (ROS) generation, cytochrome c (cyt c) release, endoplasmic reticulum (ER) stress, lysosome damage, and caspase activation, ultimately leading to apoptosis. Therefore, a detailed understanding of the influence of metal-NHCs on cancer cell apoptosis is crucial. In this review, we provide a comprehensive summary of recent advances in metal-NHC complexes that trigger apoptotic cell death via different apoptosis-related targets or signaling pathways, including B-cell lymphoma 2 (Bcl-2 family), p53, cyt c, ER stress, lysosome damage, thioredoxin reductase (TrxR) inhibition, and so forth. We also discuss the challenges, limitations, and future directions of metal-NHC complexes to elucidate their emerging application in medicinal chemistry.

Insights into the molecular basis of gastric mucosa as a first step for using Raman microscopy in paediatrics

Recent advances in endoscopic technology have allowed detailed observation of the gastric mucosa, including Raman microscopy and spectroscopy. To explore the possibilities for future diagnostic use, we discuss the measurements and molecular markers found in this tissue. The Raman spectra of 16 samples of antral mucosa and 16 samples of corpus gastric mucosa obtained from healthy donors were analysed. A stable protocol for measuring reproducible spectra was established. These data suggest that many biomarkers can be used for the rapid analysis of metabolic states and future investigations into the pathogenesis of gastrointestinal diseases.

Cardiolipin in myocardial ischaemia-reperfusion injury: From molecular mechanisms to clinical strategies

Myocardial reperfusion injury occurs when blood flow is restored after ischemia, an essential process to salvage ischemic tissue. However, this phenomenon is intricate, characterized by various harmful effects. Tissue damage in ischemia-reperfusion injury arises from various factors, including the production of reactive oxygen species, the sequestration of proinflammatory immune cells in ischemic tissues, the induction of endoplasmic reticulum stress, and the occurrence of postischemic capillary no-reflow. Secretory phospholipase A2 (sPLA2) plays a crucial role in the eicosanoid pathway by releasing free arachidonic acid from membrane phospholipids' sn-2 position. This liberated arachidonic acid serves as a substrate for various eicosanoid biosynthetic enzymes, including cyclooxygenases, lipoxygenases, and cytochromes P450, ultimately resulting in inflammation and an elevated risk of reperfusion injury. Therefore, the activation of sPLA2 directly correlates with the heightened and accelerated damage observed in myocardial ischemia-reperfusion injury (MIRI). Presently, clinical trials are in progress for medications aimed at sPLA2, presenting promising avenues for intervention. Cardiolipin (CL) plays a crucial role in maintaining mitochondrial function, and its alteration is closely linked to mitochondrial dysfunction observed in MIRI. This paper provides a critical analysis of CL modifications concerning mitochondrial dysfunction in MIRI, along with its associated molecular mechanisms. Additionally, it delves into various pharmacological approaches to prevent or alleviate MIRI, whether by directly targeting mitochondrial CL or through indirect means.

Thrombocytopenia 4 (THC4): Six novel families with mutations of the cytochrome c gene

Thrombocytopenia 4 (THC4) is an autosomal-dominant thrombocytopenia caused by mutations in CYCS, the gene encoding cytochrome c (CYCS), a small haeme protein essential for electron transport in mitochondria and cell apoptosis. THC4 is considered an extremely rare condition since only a few patients have been reported so far. These subjects presented mild thrombocytopenia and no or mild bleeding tendency. In this study, we describe six Italian families with five different heterozygous missense CYCS variants: p.Gly42Ser and p.Tyr49His previously associated with THC4, and three novel variants (p.Ala52Thr, p.Arg92Gly, and p.Leu99Val), which have been classified as pathogenic by bioinformatics and segregation analyses. Moreover, we supported functional effects of p.Ala52Thr and p.Arg92Gly on oxidative growth and respiratory activity in a yeast model. The clinical characterization of the 22 affected individuals, the largest series of THC4 patients ever reported, showed that this disorder is characterized by mild-to-moderate thrombocytopenia, normal platelet size, and function, low risk of bleeding, and no additional clinical phenotypes associated with reduced platelet count. Finally, we describe a significant correlation between the region of CYCS affected by mutations and the extent of thrombocytopenia, which could reflect different degrees of impairment of CYCS functions caused by different pathogenetic variants.

Inhibition of apoptosis and biofilm formation in Candida auris by click-synthesized triazole-bridged quinoline derivatives

Candida auris, a recent addition to the Candida species, poses a significant threat with its association to numerous hospital outbreaks globally, particularly affecting immunocompromised individuals. Given its resistance to existing antifungal therapies, there is a pressing need for innovative treatments. In this study, novel triazole bridged quinoline derivatives were synthesized and evaluated for their antifungal activity against C. auris. The most promising compound, QT7, demonstrated exceptional efficacy with a minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 0.12 μg mL-1 and 0.24 μg mL-1, respectively. Additionally, QT7 effectively disrupted mature biofilms, inhibiting them by 81.98% ± 8.51 and 89.57 ± 5.47 at MFC and 2× MFC values, respectively. Furthermore, QT7 induced cellular apoptosis in a dose-dependent manner, supported by various apoptotic markers such as phosphatidylserine externalization, mitochondrial depolarization, and reduced cytochrome c and oxidase activity. Importantly, QT7 exhibited low hemolytic activity, highlighting its potential for further investigation. Additionally, the physicochemical properties of this compound suggest its potential as a lead drug candidate, warranting further exploration in drug discovery efforts against Candida auris infections.

MicroRNA miR-20a-5p targets CYCS to inhibit apoptosis in hepatocellular carcinoma

Hepatocellular carcinoma is a primary liver cancer, characterised by diverse etiology, late diagnoses, and poor prognosis. Hepatocellular carcinoma is mostly resistant to current treatment options, therefore, identification of more effective druggable therapeutic targets is needed. We found microRNA miR-20a-5p is upregulated during mouse liver tumor progression and in human hepatocellular carcinoma patients. In this study, we elucidated the therapeutic potential of targeting oncogenic miR-20a-5p, in vivo, in a xenograft model and in two transgenic hepatocellular carcinoma mouse models via adeno-associated virus-mediated miR-20a-Tough-Decoy treatment. In vivo knockdown of miR-20a-5p attenuates tumor burden and prolongs survival in the two independent hepatocellular carcinoma mouse models. We identified and validated cytochrome c as a novel target of miR-20a-5p. Cytochrome c plays a key role in initiation of the apoptotic cascade and in the electron transport chain. We show for the first time, that miR-20a modulation affects both these key functions of cytochrome c during HCC development. Our study thus demonstrates the promising 'two birds with one stone' approach of therapeutic in vivo targeting of an oncogenic miRNA, whereby more than one key deregulated cellular process is affected, and unequivocally leads to more effective attenuation of HCC progression and significantly longer overall survival.

The Y49H cytochrome c variant enhances megakaryocytic maturation of K-562 cells

Five pathogenic variants in the gene encoding cytochrome c (CYCS) associated with mild autosomal dominant thrombocytopenia have been reported. Previous studies of peripheral blood CD34+ or CD45+ cells from subjects with the G42S CYCS variant showed an acceleration in megakaryopoiesis compared to wild-type (WT) cells. To determine whether this result reflects a common feature of the CYCS variants, the c.145T>C mutation (Y49H variant) was introduced into the endogenous CYCS locus in K-562 cells, which undergo megakaryocytic maturation in response to treatment with a phorbol ester. The c.145T>C (Y49H) variant enhanced the megakaryocyte maturation of the K-562 cells, and this effect was seen when the cells were cultured at both 18 % and 5 % oxygen. Thus, alteration of megakaryopoiesis is common to both the G42S and Y49H CYCS variants and may contribute to the low platelet phenotype. The Y49H CYCS variant has previously been reported to impair mitochondrial respiratory chain function in vitro, however using extracellular flux analysis the c.145T>C (Y49H) variant does not alter mitochondrial bioenergetics of the K-562 cells, consistent with the lack of a phenotype characteristic of mitochondrial diseases in CYCS variant families. The Y49H variant has also been reported to enhance the ability of cytochrome c to trigger caspase activation in the intrinsic apoptosis pathway. However, as seen in peripheral blood cells from G42S CYCS variant carriers, the presence of Y49H cytochrome c in K-562 cells did not significantly change their response to an apoptotic stimulus.

Perinatal maternal undernutrition in baboons modulates hepatic mitochondrial function but not metabolites in aging offspring

We previously demonstrated in baboons that maternal undernutrition (MUN), achieved by 70 % of control nutrition, impairs fetal liver function, but long-term changes associated with aging in this model remain unexplored. Here, we assessed clinical phenotypes of liver function, mitochondrial bioenergetics, and protein abundance in adult male and female baboons exposed to MUN during pregnancy and lactation and their control counterparts. Plasma liver enzymes were assessed enzymatically. Liver glycogen, choline, and lipid concentrations were quantified by magnetic resonance spectroscopy. Mitochondrial respiration in primary hepatocytes under standard culture conditions and in response to metabolic (1 mM glucose) and oxidative (100 µM H2O2) stress were assessed with Seahorse XFe96. Hepatocyte mitochondrial membrane potential (MMP) and protein abundance were determined by tetramethylrhodamine ethyl ester staining and immunoblotting, respectively. Liver enzymes and metabolite concentrations were largely unaffected by MUN, except for higher aspartate aminotransferase levels in MUN offspring when male and female data were combined. Oxygen consumption rate, extracellular acidification rate, and MMP were significantly higher in male MUN offspring relative to control animals under standard culture. However, in females, cellular respiration was similar in control and MUN offspring. In response to low glucose challenge, only control male hepatocytes were resistant to low glucose-stimulated increase in basal and ATP-linked respiration. H2O2 did not affect hepatocyte mitochondrial respiration. Protein markers of mitochondrial respiratory chain subunits, biogenesis, dynamics, and antioxidant enzymes were unchanged. Male-specific increases in mitochondrial bioenergetics in MUN offspring may be associated with increased energy demand in these animals. The similarity in systemic liver parameters suggests that changes in hepatocyte bioenergetics capacity precede detectable circulatory hepatic defects in MUN offspring and that the mitochondria may be an orchestrator of liver programming outcome.

Socialized mitochondria: mitonuclear crosstalk in stress

Traditionally, mitochondria are considered sites of energy production. However, recent studies have suggested that mitochondria are signaling organelles that are involved in intracellular interactions with other organelles. Remarkably, stressed mitochondria appear to induce a beneficial response that restores mitochondrial function and cellular homeostasis. These mitochondrial stress-centered signaling pathways have been rapidly elucidated in multiple organisms. In this review, we examine current perspectives on how mitochondria communicate with the rest of the cell, highlighting mitochondria-to-nucleus (mitonuclear) communication under various stresses. Our understanding of mitochondria as signaling organelles may provide new insights into disease susceptibility and lifespan extension.

Dual Optical Response Strategy for the Detection of Cytochrome c Using Highly Luminescent Lanthanide-Based Nanotubular Sensor Arrays

Here, we demonstrate a label-free dual optical response strategy for the detection of cytochrome c (Cyt c) with ultrahigh sensitivity using highly luminescent lanthanides containing inorganic-organic hybrid nanotubular sensor arrays. These sensor arrays are formed by the sequential incorporation of the photosensitizers 2,3-dihydroxynaphthalene (DHN) or 1,10-phenanthroline (Phen), and trivalent lanthanide terbium ions (Tb3+) into sodium lithocholate (NaLC) nanotube templates. Our sensing platform relies on the detection and quantification of Cyt c in solution by providing dual photoluminescence quenching responses from the nanotubular hybrid arrays in the presence of Cyt c. The large quenching of the sensitized Tb3+ emission within the DHN/Phen-Tb3+-NaLC nanotubular sensor arrays caused by the strong binding of the photosensitizers to Cyt c provides an important signal response for the selective detection of Cyt c. This long-lived lanthanide emission response-based sensing strategy can be highly advantageous for the detection of Cyt c in a cellular environment eliminating background fluorescence and scattering signals through time-gated measurements. The DHN containing nanotubular sensor arrays (DHN-NaLC and DHN-Tb3+-NaLC) provide an additional quenching response characterized by a unique spectral valley splitting with quantized quenching dip on the DHN fluorescence emission. This spectral quenching dip resulting from efficient FRET between the protein bound DHN photosensitizer and the heme group of Cyt c serves as an important means for specific detection and quantification of Cyt c in the concentration range of 0-30 μM with a low detection limit of around 20 nM.

Granulation characteristics of anammox sludge in response to different signal-molecule-stimulants; mediated through programmed cell death

During the anammox process, mitigation of biomass washout to increase sludge retention is an important parameter of process efficiency. Signal molecular stimulants (SMS) initiate the sludge granulations controlled by programmed cell death (PCD) of microorganisms. In this study, the aerobic granular sludge (AGS), cell fragments, extracellular polymeric substances (EPS), and AGS process effluent were tested as SMS to identify their effect on anammox granulation. The results showed that the addition of SMS increased the nitrogen removal efficiency to varying degrees, whereas the addition of AGS process supernatant, as SMS, increased the ammonia removal efficiency up to 96%. The addition of SMS was also found to increase EPS production and contributed to sludge granulation. In this process, the proportion of PCD increased and both Gaiella and Denitratisoma abundance increased from 3.54% to 5.59%, and from 1.8% to 3.42%, respectively. In conclusion, PCD was found important to increase anaerobic ammonia oxidation performance through the granulation mechanism.

The Role of Cardiolipin in Mitochondrial Function and Neurodegenerative Diseases

Cardiolipin (CL) is a mitochondria-exclusive phospholipid synthesized in the inner mitochondrial membrane. CL plays a key role in mitochondrial membranes, impacting a plethora of functions this organelle performs. Consequently, it is conceivable that abnormalities in the CL content, composition, and level of oxidation may negatively impact mitochondrial function and dynamics, with important implications in a variety of diseases. This review concentrates on papers published in recent years, combined with basic and underexplored research in CL. We capture new findings on its biological functions in the mitochondria, as well as its association with neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Lastly, we explore the potential applications of CL as a biomarker and pharmacological target to mitigate mitochondrial dysfunction.

When Our Best Friend Becomes Our Worst Enemy: The Mitochondrion in Trauma, Surgery, and Critical Illness

Common for major surgery, multitrauma, sepsis, and critical illness, is a whole-body inflammation. Tissue injury is able to trigger a generalized inflammatory reaction. Cell death causes release of endogenous structures termed damage associated molecular patterns (DAMPs) that initiate a sterile inflammation. Mitochondria are evolutionary endosymbionts originating from bacteria, containing molecular patterns similar to bacteria. These molecular patterns are termed mitochondrial DAMPs (mDAMPs). Mitochondrial debris released into the extracellular space or into the circulation is immunogenic and damaging secondary to activation of the innate immune system. In the circulation, released mDAMPS are either free or exist in extracellular vesicles, being able to act on every organ and cell in the body. However, the role of mDAMPs in trauma and critical care is not fully clarified. There is a complete lack of knowledge how they may be counteracted in patients. Among mDAMPs are mitochondrial DNA, cardiolipin, N-formyl peptides, cytochrome C, adenosine triphosphate, reactive oxygen species, succinate, and mitochondrial transcription factor A. In this overview, we present the different mDAMPs, their function, release, targets, and inflammatory potential. In light of present knowledge, the role of mDAMPs in the pathophysiology of major surgery and trauma as well as sepsis, and critical care is discussed.

Phosphorylations and Acetylations of Cytochrome c Control Mitochondrial Respiration, Mitochondrial Membrane Potential, Energy, ROS, and Apoptosis

Cytochrome c (Cytc) has both life-sustaining and cellular death-related functions, depending on subcellular localization. Within mitochondria, Cytc acts as a single electron carrier as part of the electron transport chain (ETC). When released into the cytosol after cellular insult, Cytc triggers the assembly of the apoptosome, committing the cell to intrinsic apoptosis. Due to these dual natures, Cytc requires strong regulation by the cell, including post-translational modifications, such as phosphorylation and acetylation. Six phosphorylation sites and three acetylation sites have been detected on Cytc in vivo. Phosphorylations at T28, S47, Y48, T49, T58, and Y97 tend to be present under basal conditions in a tissue-specific manner. In contrast, the acetylations at K8, K39, and K53 tend to be present in specific pathophysiological conditions. All of the phosphorylation sites and two of the three acetylation sites partially inhibit respiration, which we propose serves to maintain an optimal, intermediate mitochondrial membrane potential (ΔΨm) to minimize reactive oxygen species (ROS) production. Cytc phosphorylations are lost during ischemia, which drives ETC hyperactivity and ΔΨm hyperpolarization, resulting in exponential ROS production thus causing reperfusion injury following ischemia. One of the acetylation sites, K39, shows a unique behavior in that it is gained during ischemia, stimulating respiration while blocking apoptosis, demonstrating that skeletal muscle, which is particularly resilient to ischemia-reperfusion injury compared to other organs, possesses a different metabolic strategy to handle ischemic stress. The regulation of Cytc by these post-translational modifications underscores the importance of Cytc for the ETC, ΔΨm, ROS production, apoptosis, and the cell as a whole.

Altered conformational dynamics contribute to species-specific effects of cytochrome c mutations on caspase activation

Variants in the gene encoding human cytochrome c (CYCS) cause mild autosomal dominant thrombocytopenia. Despite high sequence conservation between mouse and human cytochrome c, this phenotype is not recapitulated in mice for the sole mutant (G41S) that has been investigated. The effect of the G41S mutation on the in vitro activities of cytochrome c is also not conserved between human and mouse. Peroxidase activity is increased in both mouse and human G41S variants, whereas apoptosome activation is increased for human G41S cytochrome c but decreased for mouse G41S cytochrome c. These apoptotic activities of cytochrome c are regulated at least in part by conformational dynamics of the main chain. Here we use computational and in vitro approaches to understand why the impact of the G41S mutation differs between mouse and human cytochromes c. The G41S mutation increases the inherent entropy and main chain mobility of human but not mouse cytochrome c. Exclusively in human G41S cytochrome c this is accompanied by a decrease in occupancy of H-bonds between protein and heme during simulations. These data demonstrate that binding of cytochrome c to Apaf-1 to trigger apoptosome formation, but not the peroxidase activity of cytochrome c, is enhanced by increased mobility of the native protein conformation.

Effects of removal of the axial methionine heme ligand on the binding of S. cerevisiae iso-1 cytochrome c to cardiolipin

The cleavage of the axial S(Met) - Fe bond in cytochrome c (cytc) upon binding to cardiolipin (CL), a glycerophospholipid of the inner mitochondrial membrane, is one of the key molecular changes that impart cytc with (lipo)peroxidase activity essential to its pro-apoptotic function. In this work, UV - VIS, CD, MCD and fluorescence spectroscopies were used to address the role of the Fe - M80 bond in controlling the cytc-CL interaction, by studying the binding of the Met80Ala (M80A) variant of S. cerevisiae iso-1 cytc (ycc) to CL liposomes in comparison with the wt protein [Paradisi et al. J. Biol. Inorg. Chem. 25 (2020) 467-487]. The results show that the integrity of the six-coordinate heme center along with the distal heme site containing the Met80 ligand is a not requisite for cytc binding to CL. Indeed, deletion of the Fe - S(Met80) bond has a little impact on the mechanism of ycc-CL interaction, although it results in an increased heme accessibility to solvent and a reduced structural stability of the protein. In particular, M80A features a slightly tighter binding to CL at low CL/cytc ratios compared to wt ycc, possibly due to the lift of some constraints to the insertion of the CL acyl chains into the protein hydrophobic core. M80A binding to CL maintains the dependence on the CL-to-cytc mixing scheme displayed by the wt species.

Impact of Choline Hydroxide-Supported Magnetic Nanoparticles on Peroxidase Activity and Conformational Stability of Cytochrome c

Nanotechnology has advanced significantly; however, little is known about the potential implications on human health-related issues, particularly blood carrying enzymes. Ionic liquids are also well-recognized for maintaining the structure and activity of enzymes. In this regard, we delineate a facile synthetic approach of preparation of Fe3O4 nanoparticles (NPs) as well as choline hydroxide [CH][OH] ionic liquid (IL)-supported Fe3O4 NPs (Fe3O4-CHOH). This approach of combining magnetic nanoparticles (MNPs) with IL results in distinctive properties, which may offer enormous utility in the field of biomedical research due to the effortless separation of MNPs by an external magnetic field. Detailed characterization of MNPs including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) was carried out. The biomolecular interactions of Fe3O4 and Fe3O4-CHOH NPs with cytochrome c (Cyt c) were studied in detail using various spectroscopic and microscopic techniques. From spectroscopic studies, it can be concluded that the secondary structure of Cyt c is more stable in the presence of Fe3O4-CHOH NPs than Fe3O4 NPs. The binding constant of Cyt c in the presence of MNPs was also calculated using the Benesi-Hildebrand equation. Furthermore, dynamic light scattering (DLS), ζ-potential, and microscopic studies were performed to study the interaction of Cyt c with MNPs. These studies provided evidence favoring the formation of bionanoconjugates of Cyt c with MNPs. Moreover, the enzymatic activity of Cyt c increases in the presence of both MNPs. The peroxidase activity of Cyt c in MNPs explicitly elucidates that the enzyme is preserved for a long time in the presence of Fe3O4-CHOH NPs. Later on, TEM and field emission scanning electron microscopy (FESEM) were also performed to gather more information regarding the morphology of Cyt c in the presence of MNPs.

Separation of the heme protein cytochrome C using a 3D structured graphene oxide bionanocomposite as an adsorbent

Proteins are of great importance for medicine and the pharmaceutical and food industries. However, proteins need to be purified prior to their application. This work investigated the application of a hydrogel bionanocomposite based on agar and graphene oxide (GO) for capturing cytochrome C (Cyto C) heme protein by adsorption from aqueous solutions with other proteins. Although applications of GO-based materials in adsorption are widely studied, the focus on semi-continuous processes remains limited. Adsorption experiments were carried out in batch and fixed bed columns. The effect of pH and ionic strength on adsorption was investigated, and there is evidence that electrostatic interactions between Cyto C and the nanocomposite were favoured at pH = 7; the adsorption capacity decreased as NaCl and KCl concentrations increased, ascribed to the weak electrostatic interaction between the protein and GO active sites in the bionanocomposite. All adsorption isotherm models (Langmuir, Freundlich, Sips) used gave suitable adjustments to the equilibrium experimental data and the kinetic models applied. The maximum adsorption capacity predicted by the Langmuir isotherm was ∼400 mgCytoC gadsorbent,dry-1, and the adsorption thermodynamics indicated a physisorption process. Tests were performed to evaluate the co-adsorption in batch, and the composite was effective in adsorbing Cyto C in solution with bovine serum albumin (BSA) and L-phenylalanine. Fixed bed tests were performed, and although protein adsorption onto nanoparticles can be challenging, the Cyto C adsorbed could be successfully recovered after desorption. Overall, the GO-based hydrogel was an effective method for cytochrome C adsorption, exhibiting a notorious potential for applications in protein separation processes.

Mitochondrial damage-associated molecular patterns: A new insight into metabolic inflammation in type 2 diabetes mellitus

The pathogenesis of diabetes is accompanied by increased levels of inflammatory factors, also known as "metabolic inflammation", which runs through the whole process of the occurrence and development of the disease. Mitochondria, as the key site of glucose and lipid metabolism, is often accompanied by mitochondrial function damage in type 2 diabetes mellitus (T2DM). Damaged mitochondria release pro-inflammatory factors through damage-related molecular patterns that activate inflammation pathways and reactions to oxidative stress, further aggravate metabolic disorders, and form a vicious circle. Currently, the pathogenesis of diabetes is still unclear, and clinical treatment focuses primarily on symptomatic intervention of the internal environment of disorders of glucose and lipid metabolism with limited clinical efficacy. The proinflammatory effect of mitochondrial damage-associated molecular pattern (mtDAMP) in T2DM provides a new research direction for exploring the pathogenesis and intervention targets of T2DM. Therefore, this review covers the most recent findings on the molecular mechanism and related signalling cascades of inflammation caused by mtDAMP in T2DM and discusses its pathogenic role of it in the pathological process of T2DM to search potential intervention targets.

Suppression of NLRP3 inflammasome activation by astragaloside IV via promotion of mitophagy to ameliorate radiation-induced renal injury in mice

Background

Irradiation (IR) promotes inflammation and apoptosis by inducing oxidative stress and/or mitochondrial dysfunction (MD). The kidneys are rich in mitochondria, and mitophagy maintains normal renal function by eliminating damaged mitochondria and minimizing oxidative stress. However, whether astragaloside IV (AS-IV) can play a protective role through the mitophagy pathway is not known.

Methods

We constructed a radiation injury model using hematoxylin and eosin (HE) staining, blood biochemical analysis, immunohistochemistry, TdT-mediated dUTP nick end labeling (TUNEL) staining, ultrastructural observation, and Western blot analysis to elucidate the AS-IV resistance mechanism for IR-induced renal injury.

Results

IR induced mitochondrial damage; the increase of creatinine (SCr), blood urea nitrogen (BUN) and uric acid (UA); and the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome and apoptosis in renal tissue. AS-IV administration attenuated the IR-induced MD and reactive oxygen species (ROS) levels in the kidney; enhanced the levels of mitophagy-associated protein [PTEN-induced putative kinase 1 (PINK1)], parkin proteins, and microtubule-associated protein 1 light 3 (LC3) II/I ratio in renal tissues; diminished NLRP3 inflammasome activation-mediated proteins [cleaved cysteinyl aspartate-specific proteinase-1 (caspase-1), interleukin-1β (IL-1β)] and apoptosis-related proteins [cleaved caspase-9, cleaved caspase-3, BCL2-associated X (Bax)]; reduced SCr, BUN, and UA levels; and attenuated the histopathological alterations in renal tissue. Conversely, mitophagy inhibitor cyclosporin A (CsA) suppressed the AS-IV-mediated protection of renal tissue.

Conclusions

AS-IV can strongly diminish the activation and apoptosis of NLRP3 inflammasome, thus attenuating the renal injury induced by radiation by promoting the PINK1/parkin-mediated mitophagy. These findings suggest that AS-IV is a promising drug for treating IR-induced kidney injury.

Aluminium phthalocyanine-mediated photodynamic therapy induces ATM-related DNA damage response and apoptosis in human oesophageal cancer cells

Introduction

Photodynamic therapy (PDT) is a light-based technique used in the treatment of malignant and non-malignant tissue. Aluminium-phthalocyanine chloride tetra sulfonate (AlPcS4Cl)-mediated PDT has been well investigated on several cancer types, including oesophageal cancer. However, the effects of (AlPcS4Cl)-mediated PDT on DNA damage response and the mechanism of cell death in oesophageal cancer needs further investigation.

Methods

Here, we examined the in vitro effects of AlPcS4Cl-mediated PDT on cell cycle, DNA damage response, oxidative stress, and intrinsic apoptotic cell death pathway in HKESC-1 oesophageal cancer cells. The HKESC-1 cells were exposed to PDT using a semiconductor laser diode (673.2 nm, 5 J/cm2 fluency). Cell viability and cytotoxicity were determined by the ATP cell viability assay and the lactate dehydrogenase (LDH) release assay, respectively. Cell cycle and DNA damage response (DDR) analyses were conducted using the Muse™ cell cycle kit and the Muse® multi-color DNA damage kit, respectively. The mode of cell death was identified using the Annexin V-FITC/PI detection assay and Muse® Autophagy LC3 antibody-based kit. The intrinsic apoptotic pathway was investigated by measuring the cellular reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨm) function, cytochrome c levels and the activity of caspase 3/7 enzymes.

Results

The results show that AlPcS4Cl-based PDT reduced cell viability, induced cytotoxicity, cell cycle arrest at the G0/G1 phase, and DNA double-strand break (DSB) through the upregulation of the ataxia telangiectasia mutated (ATM), a DNA damage sensor. In addition, the findings showed that AlPcS4Cl-based PDT induced cell death via apoptosis, which is observed through increased ROS production, reduced ΔΨm, increased cytochrome c release, and activation of caspase 3/7 enzyme. Finally, no autophagy was observed in the AlPcS4Cl-mediated PDT-treated cells.

Conclusion

Our findings showed that apoptotic cell death is the main cell death mechanism triggered by AlPcS4Cl-mediated PDT in oesophageal cancer cells.

Mitochondrial metabolism as a dynamic regulatory hub to malignant transformation and anti-cancer drug resistance

Glycolysis is the fundamental cellular process that permits cancer cells to convert energy and grow anaerobically. Recent developments in molecular biology have made it evident that mitochondrial respiration is critical to tumor growth and treatment response. As the principal organelle of cellular energy conversion, mitochondria can rapidly alter cellular metabolic processes, thereby fueling malignancies and contributing to treatment resistance. This review emphasizes the significance of mitochondrial biogenesis, turnover, DNA copy number, and mutations in bioenergetic system regulation. Tumorigenesis requires an intricate cascade of metabolic pathways that includes rewiring of the tricarboxylic acid (TCA) cycle, electron transport chain and oxidative phosphorylation, supply of intermediate metabolites of the TCA cycle through amino acids, and the interaction between mitochondria and lipid metabolism. Cancer recurrence or resistance to therapy often results from the cooperation of several cellular defense mechanisms, most of which are connected to mitochondria. Many clinical trials are underway to assess the effectiveness of inhibiting mitochondrial respiration as a potential cancer therapeutic. We aim to summarize innovative strategies and therapeutic targets by conducting a comprehensive review of recent studies on the relationship between mitochondrial metabolism, tumor development and therapeutic resistance.

PGAM5 exacerbates acute renal injury by initiating mitochondria-dependent apoptosis by facilitating mitochondrial cytochrome c release

Acute kidney injury (AKI) is a worldwide public health problem characterized by the massive loss of tubular cells. However, the precise mechanism for initiating tubular cell death has not been fully elucidated. Here, we reported that phosphoglycerate mutase 5 (PGAM5) was upregulated in renal tubular epithelial cells during ischaemia/reperfusion or cisplatin-induced AKI in mice. PGAM5 knockout significantly alleviated the activation of the mitochondria-dependent apoptosis pathway and tubular apoptosis. Apoptosis inhibitors alleviated the activation of the mitochondria-dependent apoptosis pathway. Mechanistically, as a protein phosphatase, PGAM5 could dephosphorylate Bax and facilitate Bax translocation to the mitochondrial membrane. The translocation of Bax to mitochondria increased membrane permeability, decreased mitochondrial membrane potential and facilitated the release of mitochondrial cytochrome c (Cyt c) into the cytoplasm. Knockdown of Bax attenuated PGAM5 overexpression-induced Cyt c release and tubular cell apoptosis. Our results demonstrated that the increase in PGAM5-mediated Bax dephosphorylation and mitochondrial translocation was implicated in the development of AKI by initiating mitochondrial Cyt c release and activating the mitochondria-dependent apoptosis pathway. Targeting this axis might be beneficial for alleviating AKI.

Recombinant Biogenesis and Analysis of Cytochrome c Species

Recombinant expression and biogenesis of cytochrome c species is a simple and efficient method for the production of holocytochrome c species, thus presenting an avenue for the study of cytochrome c or the cytochrome c biogenesis pathways responsible for heme attachment. Here, we describe a method for recombinant E. coli production of holocytochrome c utilizing the System I (CcmABCDEFGH) bacterial cytochrome c biogenesis pathway, followed by analysis of cytochrome c species by cell lysis and heme stain.

Aspergillus fumigatus cytochrome c impacts conidial survival during sterilizing immunity

IMPORTANCE

Aspergillus fumigatus can cause a life-threatening infection known as invasive pulmonary aspergillosis (IPA), which is marked by fungus-attributable mortality rates of 20%-30%. Individuals at risk for IPA harbor genetic mutations or incur pharmacologic defects that impair myeloid cell numbers and/or function, exemplified by bone marrow transplant recipients, patients that receive corticosteroid therapy, or patients with chronic granulomatous disease (CGD). However, treatments for Aspergillus infections remain limited, and resistance to the few existing drug classes is emerging. Recently, the World Health Organization classified A. fumigatus as a critical priority fungal pathogen. Our cell death research identifies an important aspect of fungal biology that impacts susceptibility to leukocyte killing. Furthering our understanding of mechanisms that mediate the outcome of fungal-leukocyte interactions will increase our understanding of both the underlying fungal biology governing cell death and innate immune evasion strategies utilized during mammalian infection pathogenesis. Consequently, our studies are a critical step toward leveraging these mechanisms for novel therapeutic advances.

Noninvasive low-level tragus stimulation attenuates inflammation and oxidative stress in acute heart failure

PURPOSE

Acute decompensated heart failure (ADHF) is associated with inflammation, oxidative stress, and excess sympathetic drive. It is unknown whether neuromodulation would improve inflammation and oxidative stress in acute heart failure. We, therefore, performed this proof-of-concept study to evaluate the effects of neuromodulation using noninvasive low-level tragus stimulation on inflammation and oxidative stress in ADHF.

METHODS

Nineteen patients with ejection fraction < 40% were randomized to neuromodulation 4 h twice daily (6-10 a.m. and 6-10 p.m.) (n = 8) or sham stimulation (n = 11) during hospital admission. All patients received standard-of-care treatment. Blood samples were collected at admission and discharge. Serum cytokines were assayed using standard immunosorbent techniques. Reactive oxygen species inducibility from cultured coronary endothelial cells exposed to patient sera was determined using a dihydrodichlorofluorescein probe test (expressed as fluorescein units).

RESULTS

Compared to sham stimulation, neuromodulation was associated with a significant reduction of circulating serum interleukin-6 levels (-78% vs. -9%; p = 0.012). Similarly, neuromodulation led to a reduction of endothelial cell oxidative stress in the neuromodulation group (1363 units to 978 units, p = 0.003) compared to sham stimulation (1146 units to 1083 units, p = 0.094). No significant differences in heart rate, blood pressure, or renal function were noted between the two groups.

CONCLUSION

In this proof-of-concept pilot study, in acute decompensated heart failure, neuromodulation was feasible and safe and was associated with a reduction in systemic inflammation and attenuation of coronary endothelial cellular oxidative stress.

CLINICAL TRIAL REGISTRATION

NCT02898181.

The role of mitochondria in myocardial damage caused by energy metabolism disorders: From mechanisms to therapeutics

Myocardial damage is the most serious pathological consequence of cardiovascular diseases and an important reason for their high mortality. In recent years, because of the high prevalence of systemic energy metabolism disorders (e.g., obesity, diabetes mellitus, and metabolic syndrome), complications of myocardial damage caused by these disorders have attracted widespread attention. Energy metabolism disorders are independent of traditional injury-related risk factors, such as ischemia, hypoxia, trauma, and infection. An imbalance of myocardial metabolic flexibility and myocardial energy depletion are usually the initial changes of myocardial injury caused by energy metabolism disorders, and abnormal morphology and functional destruction of the mitochondria are their important features. Specifically, mitochondria are the centers of energy metabolism, and recent evidence has shown that decreased mitochondrial function, caused by an imbalance in mitochondrial quality control, may play a key role in myocardial injury caused by energy metabolism disorders. Under chronic energy stress, mitochondria undergo pathological fission, while mitophagy, mitochondrial fusion, and biogenesis are inhibited, and mitochondrial protein balance and transfer are disturbed, resulting in the accumulation of nonfunctional and damaged mitochondria. Consequently, damaged mitochondria lead to myocardial energy depletion and the accumulation of large amounts of reactive oxygen species, further aggravating the imbalance in mitochondrial quality control and forming a vicious cycle. In addition, impaired mitochondria coordinate calcium homeostasis imbalance, and epigenetic alterations participate in the pathogenesis of myocardial damage. These pathological changes induce rapid progression of myocardial damage, eventually leading to heart failure or sudden cardiac death. To intervene more specifically in the myocardial damage caused by metabolic disorders, we need to understand the specific role of mitochondria in this context in detail. Accordingly, promising therapeutic strategies have been proposed. We also summarize the existing therapeutic strategies to provide a reference for clinical treatment and developing new therapies.

Use of 31 P magnetisation transfer magnetic resonance spectroscopy to measure ATP changes after 670 nm transcranial photobiomodulation in older adults

Mitochondrial function declines with age, and many pathological processes in neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Using 31 P magnetisation transfer magnetic resonance spectroscopy (MT-MRS) we quantify, for the first time, the effects of 670 nm PBM treatment on healthy ageing human brains. We find a significant increase in the rate of ATP synthase flux in the brain after PBM in a cohort of older adults. Our study provides initial evidence of PBM therapeutic efficacy for improving mitochondrial function and restoring ATP flux with age, but recognises that wider studies are now required to confirm any resultant cognitive benefits.

Mutant Cytochrome C as a Potential Detector of Superoxide Generation: Effect of Mutations on the Function and Properties

Cytochrome c (CytC) is a single-electron carrier between complex bc1 and cytochrome c-oxidase (CcO) in the electron transport chain (ETC). It is also known as a good radical scavenger but its participation in electron flow through the ETC makes it impossible to use CytC as a radical sensor. To solve this problem, a series of mutants were constructed with substitutions of Lys residues in the universal binding site (UBS) which interact electrostatically with negatively charged Asp and Glu residues at the binding sites of CytC partners, bc1 complex and CcO. The aim of this study was to select a mutant that had lost its function as an electron carrier in the ETC, retaining the structure and ability to quench radicals. It was shown that a mutant CytC with substitutions of five (8Mut) and four (5Mut) Lys residues in the UBS was almost inactive toward CcO. However, all mutant proteins kept their antioxidant activity sufficiently with respect to the superoxide radical. Mutations shifted the dipole moment of the CytC molecule due to seriously changed electrostatics on the surface of the protein. In addition, a decrease in the redox potential of the protein as revealed by the redox titrations of 8Mut was detected. Nevertheless, the CD spectrum and dynamic light scattering suggested no significant changes in the secondary structure or aggregation of the molecules of CytC 8Mut. Thus, a variant 8Mut with multiple mutations in the UBS which lost its ability to electron transfer and saved most of its physico-chemical properties can be effectively used as a detector of superoxide generation both in mitochondria and in other systems.

A transient vesicular glue for amplification and temporal regulation of biocatalytic reaction networks

Regulation of enzyme activity and biocatalytic cascades on compartmentalized cellular components is key to the adaptation of cellular processes such as signal transduction and metabolism in response to varying external conditions. Synthetic molecular glues have enabled enzyme inhibition and regulation of protein-protein interactions. So far, all the molecular glue systems based on covalent interactions operated under steady-state conditions. To emulate dynamic biological processes under dissipative conditions, we introduce herein a transient supramolecular glue with a controllable lifetime. The transient system uses multivalent supramolecular interactions between guanidinium group-bearing surfactants and adenosine triphosphate (ATP), resulting in bilayer vesicle structures. Unlike the conventional chemical agents for dissipative assemblies, ATP here plays the dual role of providing a structural component for the assembly as well as presenting active functional groups to "glue" enzymes on the surface. While gluing of the enzymes on the vesicles achieves augmented catalysis, oscillation of ATP concentration allows temporal control of the catalytic activities similar to the dissipative cellular nanoreactors. We further demonstrate temporal upregulation and control of complex biocatalytic reaction networks on the vesicles. Altogether, the temporal activation of biocatalytic cascades on the dissipative vesicular glue presents an adaptable and dynamic system emulating heterogeneous cellular processes, opening up avenues for effective protocell construction and therapeutic interventions.

Control of Mitochondrial Electron Transport Chain Flux and Apoptosis by Retinoic Acid: Raman Imaging In Vitro Human Bronchial and Lung Cancerous Cells

The multiple functions of cytochrome c (cyt c) and their regulation in life and death decisions of the mammalian cell go beyond respiration, apoptosis, ROS scavenging, and oxidation of cardiolipine. It has become increasingly evident that cyt c is involved in the propagation of mitogenic signals. It has been proposed that the mitogenic signals occur via the PKCδ-retinoic acid signal complex comprising the protein kinase Cδ, the adapter protein Src homologous collagen homolog (p66Shc), and cyt c. We showed the importance of retinoic acid in regulating cellular processes monitored by the Raman bands of cyt c. To understand the role of retinoids in regulating redox status of cyt c, we recorded the Raman spectra and images of cells receiving redox stimuli by retinoic acid at in vitro cell cultures. For these purposes, we incubated bronchial normal epithelial lung (BEpC) and lung cancer cells (A549) with retinoic acid at concentrations of 1, 10, and 50 µM for 24 and 48 h of incubations. The new role of retinoic acid in a change of the redox status of iron ion in the heme group of cyt c from oxidized Fe3+ to reduced Fe2+ form may have serious consequences on ATPase effectiveness and aborting the activation of the conventional mitochondrial signaling protein-dependent pathways, lack of triggering programmed cell death through apoptosis, and lack of cytokine induction. To explain the effect of retinoids on the redox status of cyt c in the electron transfer chain, we used the quantum chemistry models of retinoid biology. It has been proposed that retinol catalyzes resonance energy transfer (RET) reactions in cyt c. The paper suggests that RET is pivotally important for mitochondrial energy homeostasis by controlling oxidative phosphorylation by switching between activation and inactivation of glycolysis and regulation of electron flux in the electron transport chain. The key role in this process is played by protein kinase C δ (PKCδ), which triggers a signal to the pyruvate dehydrogenase complex. The PKCδ-retinoic acid complex reversibly (at normal physiological conditions) or irreversibly (cancer) responds to the redox potential of cyt c that changes with the electron transfer chain flux.

Noninvasive low-level tragus stimulation attenuates inflammation and oxidative stress in acute heart failure

Purpose

Acute decompensated heart failure is associated with inflammation, oxidative stress, and excess sympathetic drive. It is unknown if neuromodulation would improve inflammation and oxidative stress in acute heart failure. We, therefore, performed this proof-of-concept study to evaluate the effects of neuromodulation using noninvasive low-level Tragus stimulation on inflammation and oxidative stress in ADHF.

Methods

19 patients with ejection fraction < 40% were randomized to neuromodulation- 4 hours twice daily (6 AM-10 AM and 6 PM-10 PM) (n = 8) or sham stimulation (n = 11) during hospital admission. All patients received standard-of-care treatment. Blood samples were collected at admission and discharge. Serum cytokines were assayed using standard immunosorbent techniques. Reactive oxygen species inducibility from cultured coronary endothelial cells exposed to patient sera was determined using dihydrodichlorofluorescein probe test (expressed as fluorescein units).

Results

Compared to sham stimulation, neuromodulation was associated with a significant reduction of circulating serum Interleukin-6 levels (-78% vs -9%; p = 0.012). Similarly, neuromodulation led to reduction of endothelial cell oxidative stress, in the neuromodulation group (1363 units to 978 units, p = 0.003) compared to sham stimulation (1146 units to 1083 units, p = 0.094). No significant difference in heart rate, blood pressure or renal function were noted between the two groups.

Conclusion

In this proof-of-concept pilot study, in acute systolic heart failure, neuromodulation was feasible and safe and was associated with a reduction in systemic inflammation and attenuation of cellular oxidative stress.

Clinical trial

NCT02898181.

Axitinib attenuates the progression of liver fibrosis by restoring mitochondrial function

Liver fibrosis can progress to cirrhosis and hepatocellular carcinoma, which may eventually lead to liver failure and even death. No direct anti-fibrosis drugs are available at present. Axitinib is a new generation of potent multitarget tyrosine kinase receptor inhibitors, but its role in liver fibrosis remains unclear. In this study, a CCl4-induced hepatic fibrosis mouse model and a TGF-β1-induced hepatic stellate cell model were used to explore the effect and mechanism of axitinib on hepatic fibrosis. Results confirmed that axitinib could alleviate the pathological damage of liver tissue induced by CCl4 and inhibit the production of glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase. It also inhibited collagen and hydroxyproline deposition and the protein expression of Col-1 and α-SMA in CCl4-induced liver fibrosis. In addition, axitinib inhibited the expression of CTGF and α-SMA in TGF-β1-induced hepatic stellate cells. Further studies showed that axitinib inhibited mitochondrial damage and reduced oxidative stress and NLRP3 maturation. The use of rotenone and antimycin A confirmed that axitinib could restore the activity of mitochondrial complexes I and III, thereby inhibiting the maturation of NLRP3. In summary, axitinib inhibits the activation of HSCs by enhancing the activity of mitochondrial complexes I and III, thereby alleviating the progression of liver fibrosis. This study reveals the strong potential of axitinib in the treatment of liver fibrosis.