Mitochondrial composition and function under the control of hypoxia

Sirtuins modulators mitigate hypoxia-induced cell death due to changes in histone 3 acetylation, and mitochondrial function, dynamics, and content

Hypoxia is a key environmental factor linked to neurodevelopmental complications, primarily through its impact on mitochondrial dysfunction. Given that sirtuins regulate mitochondrial and cellular metabolism, we aimed to investigate whether pharmacological modulation of sirtuins could protect neurons from hypoxia-induced mitochondrial dysfunction and cell death. To explore this, primary cortical neurons from male Wistar rats (control) and Spontaneously Hypertensive Rats (a model for neonatal hypoxia and schizophrenia) were exposed to cobalt chloride (CoCl2) to chemically induce hypoxia. Neurons were also treated with Nicotinamide (50 μM), Resveratrol (0.5 μM), and Sirtinol (5 μM) to modulate sirtuin activity. We first assessed histone deacetylation, cell death, mitochondrial calcium retention capacity, mitochondrial membrane potential, and levels of reactive oxygen species (ROS). In addition, we analysed the expression of genes related to mitochondrial metabolism, dynamics, and biogenesis, as well as high-energy compound levels. Our data indicate that both chemical and neonatal hypoxia caused mitochondrial depolarization, reduced calcium retention, increased ROS levels, and elevated Nfe2l2 expression in primary cortical neurons. Hypoxia also led to increased expression of genes associated with mitochondrial biogenesis and fission, as well as reduced ATP levels and elevated pyruvate and lactate levels. Importantly, treatment with sirtuin modulators enhanced neuron viability, likely by further increasing Nfe2l2 expression and reducing ROS production. These modulators also improved metabolic outcomes, including higher ATP levels, and normalised pyruvate and lactate production, as well as mitochondrial fusion gene expression. Collectively, our findings suggest that sirtuin modulators could mitigate hypoxia-induced damage and may represent a potential therapeutic strategy for managing neurodevelopmental disorders.

Mechanisms of LPS-induced toxicity in endothelial cells and the protective role of geniposidic acid

Vascular inflammation and oxidative stress are critical pathogenic factors in cardiovascular diseases. Lipopolysaccharide (LPS)-induced endothelial cytotoxicity, driven by oxidative stress and inflammation, remains incompletely understood. This study highlights the molecular mechanisms underlying LPS toxicity, focusing on the ROS/JNK/NLRP3 signaling axis. LPS disrupts mitochondrial function, increases ROS accumulation, activates JNK phosphorylation, and induces NLRP3 inflammasome activation, culminating in pyroptosis through caspase-1-mediated GSDMD cleavage. Mechanistic studies with the JNK inhibitor SP600125 confirmed the critical role of the ROS/JNK/NLRP3 pathway in LPS-induced endothelial damage. Additionally, PGC-1α, a key regulator of mitochondrial homeostasis, was identified as a protective factor suppressed by LPS, exacerbating ROS overproduction and inflammasome activation. To validate these findings, geniposidic acid (GPA), a natural antioxidant and anti-inflammatory compound, was employed. GPA effectively reduced ROS levels, inhibited JNK activation, and suppressed pyroptosis, supporting its utility as a chemical tool to confirm the pivotal role of ROS/JNK/NLRP3 signaling. This study elucidates the intricate interplay between oxidative stress, mitochondrial dysfunction, and pyroptosis, providing a comprehensive framework for addressing inflammation-driven vascular damage.

Oleanolic acid derivative OA17 inhibits trophoblast apoptosis by suppressing HIF-1α nuclear translocation in SLE-associated adverse pregnancy outcomes

BACKGROUND

Systemic lupus erythematosus (SLE) primarily affects women of reproductive age and is associated with a high incidence of adverse pregnancy outcomes (APOs). Recent studies reveal that elevated HIF-1α expression in the placenta is involved in SLE-associated APOs and multiple pregnancy complications, but no clinically approved HIF-1α inhibitors exist to mitigate APOs. OA17, a pentacyclic triterpenoid derived from structural modification of oleanolic acid (OA), exhibits potent anti-inflammatory and antioxidant properties. However, OA17 function and the underlying mechanisms in SLE pregnancy outcomes remain unclear.

PURPOSE

The aim of this study was to explore the role of HIF-1α in SLE-associated APOs and to assess the therapeutic potential of OA17 as a novel treatment.

METHODS

Human placental samples and relevant clinical data were collected from participants to explore the mechanisms SLE-associated APOs. Additionally, HTR-8/SVneocells, an Extravillous trophoblast (EVT)-immortalized cell line, were subjected to hypoxia (1 % O₂) and chemicals known to stabilize HIF-1α (CoCl2 and DMOG) to mimic the upregulation of HIF-1α observed in SLE pregnancies. The relationship between HIF-1α and oxidative stress/apoptosis in the HTR-8/SVneo cells was explored through H2O2 stimulation, sh-HIF-1α, and CUT-TAG assay. Additionally, HTR-8/SVneo was treated with OA17 and pregnant MRL-lpr mice received continuous OA17 over two weeks.

RESULTS

We demonstrated that significantly increased levels of HIF-1α and heightened apoptosis in EVT cells within the placental tissues of SLE pregnancies. Mechanistically, HIF-1α bound to the SOD2 promoter to repress SOD2 transcription and regulate ROS to promote apoptosis. OA17 treatment in lupus-prone MRL/lpr mice alleviated renal injury, reduced oxidative stress and hypoxia-induced apoptosis in EVT cells by inhibiting HIF-1α nuclear translocation, thus improving APOs. In addition, OA17 treatment attenuated the biological functions of hypoxia-impaired EVT cells, including cell proliferation, invasion, and migration.

CONCLUSION

Our data suggest that elevated HIF-1α during SLE pregnancies can be considered a contributing factor to APOs, OA17 inhibits trophoblast apoptosis by suppressing HIF-1α nuclear translocation in SLE-associated APOs. OA17 could be a potential new drug for other pregnancy complications in the clinic.

Role of IP3R2-Mediated mitochondrial calcium homeostasis in early hypoxic stress injury of retinal pigment epithelial cells

OBJECTIVE

To investigate the regulatory role of IP3R2 on mitochondrial function in retinal pigment epithelial cells during the early stage of hypoxic stress preceding apoptosis.

METHODS

ARPE-19 cell line was cultured in 1 % oxygen to establish an in vitro hypoxic model. The presence of hypoxia and absence of significant apoptosis in RPE cells were confirmed through hypoxia-inducible factor HIF-1α expression and apoptosis assays respectively. Mitochondrial function was evaluated using an ATP assay kit and flow cytometry. Immunoblotting was conducted to ascertain the expression levels of mitochondrial dynamics proteins (MFN2, DRP1, TOMM20) and mitochondrial calcium-related proteins (IP3R1, IP3R2, IP3R3, VDAC1). Mitochondrial morphology was observed using confocal microscopy. The impact of small interfering RNA (siRNA)-mediated IP3R2 knockdown on apoptosis and mitochondrial function was assessed in RPE cells.

RESULTS

Under hypoxic stress before the onset of apoptosis in RPE cells, mitochondrial dysfunction and significant increase in mitochondrial calcium flux were observed, accompanied by a notable upregulation of IP3R2 expression under hypoxia. Knockdown of IP3R2 during the pre-apoptotic stage further impaired RPE function under hypoxia.

CONCLUSION

IP3R2-mediated mitochondrial calcium overload is crucial for maintaining RPE function and mitochondrial homeostasis during the pre-apoptotic stage triggered by hypoxic stress.

Hydrogen sulfide reduces oxidative stress in Huntington's disease via Nrf2

JOURNAL/nrgr/04.03/01300535-202506000-00028/figure1/v/2024-08-05T133530Z/r/image-tiff The pathophysiology of Huntington's disease involves high levels of the neurotoxin quinolinic acid. Quinolinic acid accumulation results in oxidative stress, which leads to neurotoxicity. However, the molecular and cellular mechanisms by which quinolinic acid contributes to Huntington's disease pathology remain unknown. In this study, we established in vitro and in vivo models of Huntington's disease by administering quinolinic acid to the PC12 neuronal cell line and the striatum of mice, respectively. We observed a decrease in the levels of hydrogen sulfide in both PC12 cells and mouse serum, which was accompanied by down-regulation of cystathionine β-synthase, an enzyme responsible for hydrogen sulfide production. However, treatment with NaHS (a hydrogen sulfide donor) increased hydrogen sulfide levels in the neurons and in mouse serum, as well as cystathionine β-synthase expression in the neurons and the mouse striatum, while also improving oxidative imbalance and mitochondrial dysfunction in PC12 cells and the mouse striatum. These beneficial effects correlated with upregulation of nuclear factor erythroid 2-related factor 2 expression. Finally, treatment with the nuclear factor erythroid 2-related factor 2 inhibitor ML385 reversed the beneficial impact of exogenous hydrogen sulfide on quinolinic acid-induced oxidative stress. Taken together, our findings show that hydrogen sulfide reduces oxidative stress in Huntington's disease by activating nuclear factor erythroid 2-related factor 2, suggesting that hydrogen sulfide is a novel neuroprotective drug candidate for treating patients with Huntington's disease.

Identification of mitochondrial energy metabolism genes associated with obstructive sleep apnea syndrome: integrated bioinformatics analysis

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder, which is closely related to abnormal mitochondrial energy metabolism in recent years. By analyzing gene expression data of OSAS, we identified differentially expressed genes (DEGs) related to mitochondrial energy metabolism, and further explored the function of NDUFA10 in OSAS and its potential diagnostic value. In this paper, we download OSAS related expression data from a public database and preprocess the data set using a standardized process. Gene set enrichment analysis (GSEA) was used to assess pathways associated with mitochondrial metabolism, and diagnostic models were constructed to assess the expression of key genes. ROC curve analysis was performed for common mitochondrial energy metabolism-related differentially expressed genes (Co-MEMRDEGs) and gene interaction networks were constructed. After data standardization, significantly differentially expressed genes were identified, among which NDUFA10 was identified as one of the genes most associated with OSAS. The constructed diagnostic model showed good prediction accuracy, and ROC curve analysis further verified its clinical diagnostic potential.

BCR::ABL1 expression in chronic myeloid leukemia cells in low oxygen is regulated by glutamine via CD36-mediated fatty acid uptake

BACKGROUND

Chronic myeloid leukemia (CML) is influenced by microenvironmental nutrients, glucose (Glc), and glutamine (Gln) which regulate cell proliferation, viability, and the expression of the driver oncoprotein (BCR::ABL1).

RESULTS

Our study revealed that Glc, while partially supporting alone cell growth in normoxia, is essential in low oxygen conditions, whereas Gln is ineffective. Under low oxygen, Gln reduced oxidative respiratory activity while enhancing glycolysis. In these conditions, fatty acid (FA) metabolism becomes crucial, as evidenced by increased lipid droplets (LD) accumulation when Glc was absent. Gln, in particular, drives CD36-mediated FA uptake, suppressing the BCR::ABL1 oncoprotein and facilitating cell survival. By co-culturing leukemia cells with adipocytes, one of the main bone marrow (BM) cell components, we observed an enhanced FA release, suggesting a link between FA, microenvironmental BM cells, and the maintenance of leukemic stem cells (LSC).

METHODS

K562 and KCL22 cell lines were subjected to Glc and/or Gln deprivation under hypoxic conditions (96 h at 0.1% O2). Metabolic profiling was conducted through the Seahorse XFe96 analyzer, and the contribution of L-Glutamine-13C5 to FA de novo synthesis was determined via GC/MS. Intracellular neutral LD were measured using BODIPY 493/503 in confocal microscopy and flow cytometry, with their presence and morphology further examined via transmission electron microscopy. BCR::ABL1 as well as several FA-related markers were evaluated via Western Blotting, whilst CD36 was determined through flow cytometry. LC2 assay was used for measuring leukemia stem cell potential by inhibiting FA uptake via the usage of the Sulfo-N-Succinimidyl Oleate, a CD36 inhibitor. qPCR was exploited to detect markers of FA secretion in CML-adipocytes co-culture together with Nile Red staining to assess free FA in the media.

CONCLUSIONS

These findings underscore the central role of FA in the regulation of the LSC compartment of CML, highlighting the importance of Gln in facilitating CML cell survival under restrictive metabolic conditions and preparing the cell population for expansion upon the release of these restrictions.

HuMSCs-derived exosomal YBX1 participates in oxidative damage repair in granulosa cells by stabilizing COX5B mRNA in an m5C-dependent manner

Mitochondrial dysfunction and cell senescence are triggered by reactive oxygen species (ROS) in granulosa cells (GCs), leading to premature ovarian insufficiency (POI). Human umbilical cord mesenchymal stem cell-derived exosome (HuMSCs-Ex, H-Ex)-based treatments have been shown to alleviate ROS-induced POI, but knowledge about the underlying therapeutic mechanisms is limited. Here, we observed that the 5-methylcytosine (m5C) RNA methyltransferase tRNA aspartic acid methyltransferase 1 (TRDMT1) promoted the translation of COX subunit 5B (COX5B) in a manner dependent on its catalytic activity and downstream m5C reader Y-box binding protein 1 (YBX1), which was decreased in prematurely senescent GCs but abundant in H-Ex. Mechanistically, YBX1 released by H-Ex recognizes the TRDMT1-mediated m5C modification of COX5B and directly binds to COX5BC-153 via LYS-92, thereby reducing ROS accumulation and improving mitochondrial function in GCs under oxidative stress, providing new insights into the theoretical basis for the great clinical potential of H-Ex in the treatment of POI.

Origin and evolution of mitochondrial inner membrane composition

Unique membrane architectures and lipid building blocks underlie the metabolic and non-metabolic functions of mitochondria. During eukaryogenesis, mitochondria likely arose from an alphaproteobacterial symbiont of an Asgard archaea-related host cell. Subsequently, mitochondria evolved inner membrane folds known as cristae alongside a specialized lipid composition supported by metabolic and transport machinery. Advancements in phylogenetic methods and genomic and metagenomic data have suggested potential origins for cristae-shaping protein complexes, such as the mitochondrial contact site and cristae-organizing system (MICOS). MICOS protein homologs function in the formation of cristae-like intracytoplasmic membranes (ICMs) in diverse extant alphaproteobacteria. The machinery responsible for synthesizing key mitochondrial phospholipids - which cooperate with cristae-shaping proteins to establish inner membrane architecture - could have also evolved from a bacterial ancestor, but its origins have been less explored. In this Review, we examine the current understanding of mitochondrial membrane evolution, highlighting distinctions between prokaryotic and eukaryotic mitochondrial-specific proteins and lipids and their differing roles in shaping cristae and ICM architecture, and propose a model explaining the concurrent specialization of the mitochondrial lipidome and inner membrane structure in eukaryogenesis. We discuss how advancements across a range of disciplines are shedding light on how multiple membrane components co-evolved to support the central functions of eukaryotic mitochondria.

N-acetylserotonin derivative ameliorates hypoxic-ischemic brain damage by promoting PINK1/Parkin-dependent mitophagy to inhibit NLRP3 inflammasome-induced pyroptosis

Neonatal hypoxic-ischemic brain damage is the main cause of hypoxic-ischemic encephalopathy and cerebral palsy, whose clinical treatment is still limited to therapeutic hypothermia with limited efficacy. N-[2-(5-hydroxy-1H-indol-3-yl) ethyl]-2-oxopiperidine-3-carboxamide (HIOC), a derivative of N-acetylserotonin, has shown neuroprotective properties. This study was conducted to evaluate the neuroprotective and molecular mechanisms of HIOC. We established an in vitro model using Oxygen-glucose deprivation/reoxygenation (OGD/R) in HT22 cells, alongside an in vivo model via the modified Rice-Vannucci method. The results showed that HIOC reduced OGD/R-induced HT22 cell pyroptosis and inhibited NOD-like receptor pyrin domain- containing protein 3 (NLRP3) inflammasome activation. With the addition of the mitophagy inhibitor 3-MA, we demonstrated that HIOC promoted PTEN-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy to reduce HT22 cell pyroptosis. Mechanistically, HIOC stimulated mitophagy to remove damaged mitochondria. The clearance of injured mitochondria reduced reactive oxygen species generation, which consequently inhibited NLRP3 inflammasome expression. In vivo, HIOC remarkably lessened cerebral blood flow, infarct volume, neuronal injury by activating mitophagy. HIOC activated mitophagy to produce antipyroptosis effects. Together, our finding demonstrated that HIOC improves brain injury by promoting PINK1/Parkin-dependent mitophagy to inhibit NLRP3 inflammasome activation and pyroptosis, suggesting its potential for hypoxic-ischemic brain damage treatment.

Postmortem mitochondrial membrane potential dynamics as a temperature-independent biomarker for early postmortem interval estimation

BACKGROUND

Accurate determination of postmortem interval (PMI) and cause of death (COD) is a critical challenge in forensic pathology, with significant implications for criminal investigations. Traditional PMI estimation methods are based on macroscopic changes and are influenced by environmental factors and investigator subjectivity. Recent advances in molecular biology have shown that certain cellular structures, such as mitochondria, retain functionality after death, making them potential biomarkers for forensic assessment. As mitochondria play a central role in cellular metabolism and respond dynamically to post-mortem hypoxia, investigation of mitochondrial membrane potential (ΔΨm) may provide a quantifiable and objective method for estimating PMI.

RESULTS

We successfully isolated mitochondria from post-mortem tissues and cultured cells, confirming their purity and membrane integrity. Regression analysis showed a strong linear correlation between ΔΨm and PMI in brain, myocardium and skeletal muscle within the first 15-18 h postmortem, with skeletal muscle showing the highest correlation coefficient. ΔΨm values remained stable at different temperatures, suggesting that it is a robust biomarker for estimating PMI. In vitro experiments under hypoxic conditions revealed a transient increase in ΔΨm at 24 h, accompanied by ATP depletion, ROS accumulation and shifts in mitochondrial fission and fusion dynamics, indicating mitochondrial adaptation to oxygen deprivation.

CONCLUSIONS

These findings highlight ΔΨm as a promising temperature stable biomarker for early assessment of PMI. The observed mitochondrial adaptations suggest that ΔΨm-based models may improve forensic accuracy and provide insights into postmortem metabolic processes. Further validation with human postmortem samples is essential to refine these models and explore their applicability to COD determination.

Short-term sustained hypoxia distinctly affects subpopulations of carotid body glomus cells from rats

The main O2 arterial chemoreceptors are the carotid bodies (CBs), which mediate hyperventilation in response to short-term sustained hypoxia (SH). CBs contain glomus cells expressing K+ channels, which are inhibited by hypoxia, leading to neurotransmitter release. ATP released by CBs and type II cells has been considered essential for chemosensory processing under physiological and pathophysiological conditions. Although the systemic effects of chronic activation of CBs by SH are well known, the early (first 24 h) cellular and molecular mechanisms in CBs as well as the effects of short-term SH on populations of glomus cells are still poorly understood. Here, we show that SH (10% O2 for 24 h) depolarizes the membrane potential of one population of glomus cells, mediated by increases in inward current, but does not affect the ATP release by CBs. In addition, SH promotes a reduction in their maximum outward current, mediated by voltage-gated K+ channels. SH also affected sensitivity to acute hypoxia in one glomus cell subpopulation. As for the content of mitochondrial proteins, we observed increases in the citrate synthase, Tom-20, and succinate dehydrogenase (mitochondrial complex II) per cell of CBs after SH. Our results demonstrate important cellular and molecular mechanisms of plasticity in CBs from rats after only 24 h of SH, which may contribute to the generation of cardiovascular and ventilatory adjustments observed in this experimental model.NEW & NOTEWORTHY Our study revealed two subpopulations of glomus cells of carotid bodies (CBs) with specific electrophysiological properties, which were differentially affected by short-term sustained hypoxia (SH; 10% O2 for 24 h). Our experiments showed that SH also affected the sensitivity to acute hypoxia of these glomus cell subpopulations differently. Our molecular analyses allowed us to identify important adaptations in the content of CB mitochondrial proteins that participate in the Krebs cycle and form the electron transport chain.

Effects of in vitro cytochalasin D and hypoxia on mitochondrial energetics and biogenesis, cell signal status and actin/tubulin/Hsp/MMP entity in air-breathing fish heart

The cardiac actin cytoskeleton has a dynamic pattern of polymerisation. It is uncertain how far actin destabilisation impacts mitochondrial energetics and biogenesis, cell signal status, and structural entities in cardiomyocytes, particularly in hypoxic conditions. We thus tested the in vitro action of cytochalasin D (Cyt D), an inhibitor of actin polymerisation, in hypoxic ventricular explants to elucidate the role of the actin in mitochondrial energetics and biogenesis, cell signals and actin/tubulin/hsps/MMPs dynamics in hypoxic air-breathing fish hearts. The COX activity increased upon Cyt D exposure, whereas hypoxia lowered COX and SDH activities but increased LDH activity. The ROS increased, and NO decreased by Cyt D. COX and LDH activities, and NO content reversed after Cyt D exposure in hypoxic hearts. Cyt D exposure upregulated actin isoform expression (Actc1 and Actb1) but downregulated tubulin isoform (Tedc1). Hypoxia upregulated actin (Acta1a, Actb1, Actb2, Actc1a) tubulin (Tuba, Tubb5, Tedc1, Tubd1) and hsp (Hspa5, Hspa9, Hspa12a, Hspa14, Hspd1, Hsp90) isoform transcript expression and Cyt D in hypoxic hearts reversed these isoform's expression. Hypoxia upregulated Mmp2 and 9 transcript expressions but downregulated Mfn1, Fis1, Nfkb1, Prkacaa, and Aktip expressions, and Cyt D exposure reversed almost all these markers in hypoxic hearts. The data provide novel evidence for the mechanistic role of actin in integrating mitochondrial energetics and biogenesis, cell signal status and actin/tubulin/Hsp/MMP entity, indicating its critical cardioprotective role in defending against hypoxia. Besides proposing an air-breathing fish heart as a model, the study further brings the therapeutic potential of Cyt D towards hypoxia intervention.

HIF-1α mediates mitochondrial damage by down-regulating ALKBH7 expression to promote the aberrant activation of FLS in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and progressive joint destruction. Existing evidence indicates that hypoxia potentially contributes to the pathology of RA, though the specific mechanism remains unidentified. In this study, we explored the molecular mechanism through which the hypoxia-inducible factor (HIF-1α) contributed to the pathological process of RA. Our preliminary results suggested that hypoxia stimulates the activation of fibroblast-like synoviocytes (FLS) by inducing mitochondrial damage to activate cGAS-STING signaling, which can be effectively inhibited by silencing HIF-1α. In line with this, HIF-1α deficiency significantly alleviated the symptoms of collagen-induced arthritis (CIA) mice. RNA-Seq and CUT-Tag analysis revealed that HIF-1α down-regulated the expression of AlkB homologue 7 (ALKBH7) by acting on the ALKBH7 promoter site on chromosome 19 6372400-6372578. Using dual luciferase reporter analysis, we identified that ACCGTGGC as the motif to which HIF-1α bound directly. Subsequently, we demonstrated that knockdown of ALKBH7 induces mitochondrial damage and activates cGAS-STING signaling by downregulating the expression of UQCRC2. Conversely, overexpression of ALKBH7 could resist hypoxia-induced mitochondrial damage and FLS activation. In conclusion, HIF-1α triggers mitochondrial damage by downregulating the expression of ALKBH7 thereby promoting FLS activation, which may be the molecular mechanism by which hypoxia is involved in the pathological process of RA. Hypoxia promotes the activation of FLS through the induction of mitochondrial damage, which subsequently activates cGAS-STING signaling. Mechanistically, HIF-1α triggers mitochondrial damage by downregulating the expression of ALKBH7 in a target manner. Furthermore, the deletion of ALKBH7 leads to mitochondrial damage under hypoxic conditions, primarily through the downregulation of UQCRC2, as opposed to other complexes.

The pro-inflammatory cytokine IL6 suppresses mitochondrial function via the gp130-JAK1/STAT1/3-HIF1α/ERRα axis

Chronic inflammation and a decline in mitochondrial function are hallmarks of aging. Here, we show that the two mechanisms may be linked. We found that interleukin-6 (IL6) suppresses mitochondrial function in settings where PGC1 (both PGC1α and PGC1β) expression is low. This suppression is mediated by the JAK1/STAT1/3 axis, which activates HIF1α through non-canonical mechanisms involving upregulation of HIF1A and ERRα transcription, and subsequent stabilization of the HIF1A protein by ERRα. HIF1α, in turn, inhibits ERRα, which is a master regulator of mitochondrial biogenesis, thus contributing to the inhibition of mitochondrial function. When expressed at higher levels, PGC1 rescues ERRα to boost baseline mitochondrial respiration, including under IL6-treated conditions. Our study suggests that inhibition of the IL6 signaling axis could be a potential treatment for those inflammatory settings where mitochondrial function is compromised.

Ferulic acid inhibits ox-LDL-induced ferroptosis and apoptosis in RAW 264.7 cells via the HIF-1 signaling pathway

Objective

Ferulic acid (FA) has shown potential in treating atherosclerosis (AS) by improving lipid metabolism and exerting anti-hypoxic effects. This study aimed to validate the mechanism of FA in AS through in vitro experiments.

Methods

Network analysis was employed to predict the mechanisms underlying the therapeutic effects of FA on AS. An in vitro foam cell model was established using RAW 264.7 cells treated with ox-LDL. Cellular lipid accumulation was detected using Oil Red O staining; cell viability was assessed by cell counting kit-8; mitochondrial morphology and function were evaluated by transmission electron microscopy and JC-1 staining; apoptosis levels were detected by TUNEL and DAPI staining; mitochondrial Fe2+ content was measured by Mito-FerroGreen; and Western blot was performed to determine the protein expression levels of HIF-1α, Bax, Bcl2, GPX4, and EGFR.

Results

Network analysis suggested that FA may exert its therapeutic effects on AS through the HIF-1 signaling pathway and is closely associated with the regulation of ferroptosis and apoptosis. FA upregulated the expression of ALOX5, BCL2, ERN1, GPX4, NOS3, and SLC2A1 mRNA and downregulated the expression of BAX, CYCS, EGFR, FLT1, HIF1A, NFKB1, NOS2, PARP1, and STAT3 mRNA. In vitro experiments demonstrated that FA reduces lipid accumulation, increases cell viability, improves mitochondrial function, and decreases reactive oxygen species content. Additionally, FA inhibited ferroptosis and apoptosis by suppressing the HIF-1 signaling pathway, up-regulating the expression of GPX4 and Bcl2, and down-regulating the expression of HIF-1α and Bax protein. HIF-1 agonists reversed these effects by activating the HIF-1 signaling pathway.

Conclusion

FA improves mitochondrial function and suppresses ferroptosis and apoptosis by inhibiting the HIF-1 signaling pathway, thereby treating AS.

Hypoxia induced mitophagy generates reversible metabolic and redox heterogeneity with transient cell death switch driving tumorigenesis

Tumor hypoxia determines tumor growth, metastasis, drug resistance, and tumor heterogeneity through multiple mechanisms, largely dependent on the extent of hypoxia, further modulated by re-oxygenation events. In order to track the cell fates under hypoxia and re-oxygenation, we have developed a sensor cell for real-time tracking of apoptotic, necrotic, and surviving mitophagy cells under hypoxia and re-oxygenation. The study using this sensor revealed a cell death switch from apoptosis to necrosis by hypoxia-exposed cells under re-oxygenation, where mitophagy plays a key role in acquiring temporally evolving functional phenotypes, including metabolic heterogeneity and mitochondrial redox heterogeneity. RNA transcriptomics also revealed a temporally evolving genomic landscape supporting the complex transcriptional plasticity of cells as a non-genetic adaptive event. Interestingly, cells regained from these distinct stages retained their metastatic potential despite slow growth in animal models. Overall, the study demonstrated that cells acquire distinct functions by tumor hypoxia and re-oxygenation, secondarily acquiring transient functional traits and metabolic heterogeneity governed by cell inherent mitochondrial dynamics. Such cell autonomous temporal alterations in cell states governed by organelle integrity with distinct cell proliferation and apoptosis-necrosis switch may be advantageous for the growing tumor to evolve under complex microenvironmental stress, further contributing to tumorigenesis.

Sodium-Glucose Transporter-2 Inhibitors (SGLT2i) and Myocardial Ischemia: Another Compelling Reason to Consider These Agents Regardless of Diabetes

In recent years, the introduction of sodium-glucose transporter-2 inhibitors (SGLT2is) marked a significant advancement in the treatment of cardiovascular disease (CVD). Beyond their known effects on glycemic control and lipid profile, SGLT2is demonstrate notable benefits for cardiovascular morbidity and mortality, regardless of diabetic status. These agents are currently recommended as first-line therapies in patients with heart failure, both with reduced and preserved ejection fraction, as they improve symptoms and reduce the risk of hospitalization. While several studies have demonstrated that SGLT2is can reduce the incidence of major adverse cardiovascular events (MACEs), the true impact of these agents on atherosclerosis progression and myocardial ischemia remains to be fully understood. A global beneficial effect related to improved glycemic and lipid control could be hypothesized, even though substantial evidence shows a direct impact on molecular pathways that enhance endothelial function, exhibit anti-inflammatory properties, and provide myocardial protection. In this context, this narrative review summarizes the current knowledge regarding these novel anti-diabetic drugs in preventing and treating myocardial ischemia, aiming to define an additional area of application beyond glycemic control and heart failure.

Adaptation of Natural Killer Cells to Hypoxia: A Review of the Transcriptional, Translational, and Metabolic Processes

As important innate immune cells, natural killer (NK) cells play an essential role in resisting pathogen invasion and eliminating transformed cells. However, the hypoxic microenvironment caused by disease conditions is an important physicochemical factor that impairs NK cell function. With the increasing prominence of NK cells in immunotherapy, there has been a surge of interest in developing biological means through which NK cells may overcome the inhibition caused by hypoxia in disease conditions. Although the effects of hypoxic conditions in shaping the functions of NK cells have been increasingly recognized and investigated, reviews have been scantly. A comprehensive understanding of how NK cells adapt to hypoxia can provide valuable insights into how the functional capacity of NK cells may be restored. This review focuses on the functional alterations of NK cells in response to hypoxia. It delineates the mechanisms by which NK cells adapt to hypoxia at the transcriptional, metabolic, translational levels. Furthermore, given the complexity of the hypoxic microenvironment, we also elucidated the effects of key hypoxic metabolites on NK cells. Finally, this review discusses the current clinical therapies derived from targeting hypoxic NK cells. The study of NK cell adaptation to hypoxia has yielded new insights into immunotherapy. These insights may lead to development of novel strategies to improve the treatment of infectious diseases and cancer.

Signaling Pathways Involved in Acute Pancreatitis

Acute pancreatitis (AP) is a common digestive emergency with high morbidity and mortality. Over the past decade, significant progress has been made in understanding the mechanisms of AP, including oxidative stress, disruptions in calcium homeostasis, endoplasmic reticulum stress, inflammatory responses, and various forms of cell death. This review provides an overview of the typical signaling pathways involved and proposes the latest clinical translation prospects. These strategies are important for the early management of AP, preventing multi-organ injury, and improving the overall prognosis of the disease.

Impact of Oxygen Availability on the Organelle-Specific Redox Potentials and Stress in Recombinant Protein Producing Komagataella phaffii

The yeast Komagataella phaffii (syn. Pichia pastoris) is a highly effective and well-established host for the production of recombinant proteins. The redox balance of its secretory pathway, which is multi-organelle dependent, is of high importance for producing secretory proteins. Redox imbalance and oxidative stress can significantly influence protein folding and secretion. Glutathione serves as the main redox buffer of the cell and cellular redox conditions can be assessed through the status of the glutathione redox couple (GSH-GSSG). Previous research often focused on the redox potential of the endoplasmic reticulum (ER), where oxidative protein folding and disulphide bond formation occur. In this study, in vivo measurements of the glutathione redox potential were extended to different subcellular compartments by targeting genetically encoded redox sensitive fluorescent proteins (roGFPs) to the cytosol, ER, mitochondria and peroxisomes. Using these biosensors, the impact of oxygen availability on the redox potentials of the different organelles was investigated in non-producing and producing K. phaffii strains in glucose-limited chemostat cultures. It was found that the transition from normoxic to hypoxic conditions affected the redox potential of all investigated organelles, while the exposure to hyperoxic conditions did not impact them. Also, as reported previously, hypoxic conditions led to increased recombinant protein secretion. Finally, transcriptome and proteome analyses provided novel insights into the short-term response of the cells from normoxic to hypoxic conditions.

hUC-MSC preserves erectile function by restoring mitochondrial mass of penile smooth muscle cells in a rat model of cavernous nerve injury via SIRT1/PGC-1a/TFAM signaling

BACKGROUND

Cavernous nerve injury-induced erectile dysfunction (CNI-ED) is a common complication following radical prostatectomy and severely affects patients' quality of life. The mitochondrial impairment in corpus cavernosum smooth muscle cells (CCSMCs) may be an important pathological mechanism of CNI-ED. Previous studies have shown that transplantation of human adipose derived stem cells (ADSC) can alleviate CNI-ED in a rat model. However, little is known about the effect of human umbilical cord mesenchymal stem cells (hUC-MSC) on CNI-ED. It remains unclear whether hUC-MSC can ameliorate mitochondrial damage in CCSMCs. In this study, we aimed to investigate the impacts of hUC-MSC on the mitochondrial mass and function of CCSMCs, as well as elucidate its underlying molecular mechanism.

METHODS

The CNI-ED rat model was established by bilaterally crushing cavernous nerves. Subsequently, hUC-MSC were transplanted into the cavernosum and ADSC were injected as a positive control group. Erectile function evaluation and histological detection were performed 4 weeks after cell transplantation. In vitro, CCSMCs underwent hypoxia and were then co-cultured with ADSC or hUC-MSC using a transwell system. The mitochondrial mass and function, as well as signaling pathways, were investigated. To explore the role of the SIRT1/PGC-1α/TFAM pathway in regulating mitochondrial biogenesis of CCSMCs, we knocked down SIRT1 by siRNA.

RESULTS

The administration of hUC-MSC significantly improved erectile function of CNI-ED rats and reduced the ratio of collagen to smooth muscle. Specifically, hUC-MSC treatment restored mitochondrial mass and function in CCSMCs injured by CNI or hypoxia, and inhibited the apoptosis of CCSMCs. Mechanistically, the application of hUC-MSC activated SIRT1/PGC-1α/TFAM pathway both in rat penile tissues and CCSMCs. In addition, knockdown of SIRT1 in CCSMCs abolished the protective effects of hUC-MSC on mitochondrial mass and function, while leading to an increase in cellular apoptosis.

CONCLUSIONS

hUC-MSC contribute to the recovery of erectile function in CNI-ED rats by restoring mitochondrial mass and function of CCSMCs through the SIRT1/PGC-1α/TFAM pathway. Our present study offers new insights into the role and molecular mechanisms of hUC-MSC in regulating mitochondrial homeostasis, thereby facilitating the restoration of the erectile function in CNI-ED.

In-depth proteomics and Phosphoproteomics reveal biomarkers and molecular pathways of chronic intermittent hypoxia in mice

Obstructive sleep apnea (OSA) syndrome is characterized by Chronic Intermittent Hypoxia (CIH). In this study, we employed Data-independent acquisition (DIA) Mass Spectrometry to conduct comprehensive proteomic and phosphoproteomic profiling of a murine model subjected to Chronic Intermittent Hypoxia (CIH), a model we had previously established. Utilizing three CIH and three normal control genioglossus samples, we gathered valuable insights into the molecular alterations associated with CIH. Our analyses identified a total of 4576 protein groups and 13,867 phosphosites. Differential analysis of the proteomic data highlighted a significant upregulation of Ras signaling (Egf, Ngf, and Fyb1) and calcium signaling (Tnn, Thbs4, and Ppp2r2d) in CIH samples, contrasting with a notable decrease in oxidative phosphorylation (Atp5mf, Atp5me, and Atp5mg). Additionally, we observed a substantial increase in the phosphorylation of PI3K-AKT signaling (Ptk2_Y861, Mapk3_T203, and Eif4b_S230) and HIF-1 signaling (Gapdh_S208, Eno3_T229, and Camk2b_T382) in CIH samples. These findings prompted a deeper investigation into the association of the characterized proteins and phosphoproteins with Obstructive Sleep Apnea (OSA). The comprehensive profiling revealed molecular signatures that may serve as valuable insights into the pathophysiology of chronic intermittent hypoxia and its link to obstructive sleep apnea. Our observations provide a foundation for future research endeavors, offering potential avenues for advancing our understanding and treatment strategies for these conditions. SIGNIFICANCE: The significance of this study lies in its comprehensive exploration of the molecular mechanisms underpinning Chronic Intermittent Hypoxia (CIH), a key feature of Obstructive Sleep Apnea (OSA). By employing Data-independent acquisition (DIA) Mass Spectrometry, this research provides an in-depth proteomic and phosphoproteomic analysis, uncovering critical signaling pathways and molecular alterations associated with CIH. The identification of significant changes in Ras and calcium signaling pathways, along with increased phosphorylation in PI3K-AKT and HIF-1 signaling, offers novel insights into the pathophysiological processes involved in CIH and OSA. These findings not only enhance our understanding of the molecular basis of OSA but also pave the way for the development of targeted therapeutic strategies, ultimately contributing to better management and treatment of OSA and related conditions.

The systemic evolutionary theory of the origin of cancer (SETOC): an update

The Systemic Evolutionary Theory of the Origin of Cancer (SETOC) is a recently proposed theory founded on two primary principles: the cooperative and endosymbiotic process of cell evolution as described by Lynn Margulis, and the integration of complex systems operating in eukaryotic cells, which is a core concept in systems biology. The SETOC proposes that malignant transformation occurs when cells undergo a continuous adaptation process in response to long-term injuries, leading to tissue remodeling, chronic inflammation, fibrosis, and ultimately cancer. This process involves a maladaptive response, wherein the 'endosymbiotic contract' between the nuclear-cytoplasmic system (derived from the primordial archaeal cell) and the mitochondrial system (derived from the primordial α-proteobacterium) gradually breaks down. This ultimately leads to uncoordinated behaviors and functions in transformed cells. The decoupling of the two cellular subsystems causes transformed cells to acquire phenotypic characteristics analogous to those of unicellular organisms, as well as certain biological features of embryonic development that are normally suppressed. These adaptive changes enable cancer cells to survive in the harsh tumor microenvironment characterized by low oxygen concentrations, inadequate nutrients, increased catabolic waste, and increased acidity. De-endosymbiosis reprograms the sequential metabolic functions of glycolysis, the TCA cycle, and oxidative phosphorylation (OxPhos). This leads to increased lactate fermentation (Warburg effect), respiratory chain dysfunction, and TCA cycle reversal. Here, we present an updated version of the SETOC that incorporates the fundamental principles outlined by this theory and integrates the epistemological approach used to develop it.

Psychoneuroimmunology of Mood Disorders

Recent research has shed light on the intricate relationship between mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BD), and inflammation. This chapter explores the complex interplay involving immune and metabolic dysfunction in the pathophysiology of these disorders, emphasizing their association with autoimmunity/inflammatory conditions, chronic low-grade systemic inflammation, T cell overactivation, and immunosenescence. This perspective underscores the notion that MDD and BD are not solely brain disorders, highlighting their nature as multi-system conditions.

Pan-cancer association of a mitochondrial function score with genomic alterations and clinical outcome

Mitochondria are pivotal in cellular energy metabolism and have garnered significant attention for their roles in cancer progression and therapy resistance. Despite this, the functional diversity of mitochondria across various cancer types remains inadequately characterized. This study seeks to fill this knowledge gap by introducing and validating MitoScore-a novel metric designed to quantitatively assess mitochondrial function across a wide array of cancers. Our investigation evaluates the capacity of MitoScore not only to distinguish between tumor and adjacent normal tissues but also to serve as a predictive marker for clinical outcomes. We analyzed gene expression data from 24 cancer types and corresponding normal tissues using the TCGA database. MitoScore was calculated by summing the normalized expression levels of six mitochondrial genes known to be consistently altered across multiple cancers. Differential gene expression was assessed using DESeq2, with a focus on identifying significant changes in mitochondrial function. MitoScore's associations with tumor proliferation, hypoxia, aneuploidy, and clinical outcomes were evaluated using Spearman's correlation, linear regression, and Kaplan-Meier survival analyses. MitoScore was significantly higher in tumor tissues compared to normal tissues across most cancer types (p < 0.001). It positively correlated with tumor proliferation rates (r = 0.46), hypoxia scores (r = 0.61), and aneuploidy (r = 0.44), indicating its potential as a marker of aggressive tumor behavior. High MitoScore was also associated with poorer prognosis in several cancer types, suggesting its utility as a predictive biomarker for clinical outcomes. This study introduces MitoScore, a metric for mitochondrial activity often elevated in tumors and linked to poor prognosis. It correlates positively with hypoxia and negatively with stromal and immune infiltration, highlighting mitochondria's role in the tumor microenvironment. MitoScore's association with genomic instability, such as aneuploidy, suggests mitochondrial dysfunction contributes to cancer progression. Despite challenges in mitochondrial-targeted therapies, MitoScore may identify tumors responsive to such treatments, warranting further research for clinical application.

Impacts and mechanisms of PM2.5 on bone

Osteoporosis is a metabolic bone disease, which is characterized by a decreased bone mass and deterioration of bone microstructure, resulting in increased bone fragility and a higher risk of fracture. The main pathological process of osteoporosis is the dynamic imbalance between bone absorption and bone formation, which can be caused by various factors such as air pollution. Particulate matter (PM)2.5 refers to the fine particles in the atmosphere, which are small in volume and large in specific surface area. These particles are prone to carrying toxic substances and have negative effects on several extrapulmonary organs, including bones. In this review, we present relevant data from studies, which show that PM2.5 is associated with abnormal bone turnover and osteoporosis. PM2.5 may cause or aggravate bone loss by stimulating an inflammatory response, inducing oxidative damage, reducing estrogen efficiency by competitive binding to estrogen receptors, or endocrine disorder mediated by binding with aromatic hydrocarbon receptors, and affecting the synthesis of vitamin D to reduce calcium absorption. The cellular and molecular mechanisms involved in these processes are also summarized in this review.

Hydrogen gas inhalation prior to high-intensity training reduces attenuation of nitric oxide bioavailability in male rugby players

Background

Inhalation of hydrogen gas (H2) as an antioxidant supplement may alleviate exercise-induced oxidative damage and protect post-exercise hydrogen peroxide signaling, which may help mediate beneficial exercise adaptation. The aims of this study were to determine the effects of H2 inhalation on plasma nitric oxide (NO) level and its synthesis precursor in professional athletes.

Methods

A randomized, placebo-controlled, double-blind, crossover trial was conducted with professional male rugby players for 3 weeks. Participants underwent 1 week of H2 supplementation and 1 week of placebo treatment prior to daily sessions of high-intensity exercise training, separated by 1 week of low-intensity training as a washout.

Results

Two-way (supplementation and time) repeated-measures analyses of variance showed that NO, L-arginine, and tetrahydrobiopterin levels in the H2 inhalation group were significantly higher than those in the placebo group after exercise (D6) and remained higher after 24 h of rest (D7). Levels of hydroxydeoxyguanosine and interleukin 6 were lower in the H2 inhalation week than in the placebo week on D6 and D7. In addition, total antioxidant levels were significantly higher with H2 inhalation than with placebo.

Significance

These results suggest that H2 inhalation helps to maintain NO signaling after exercise and to alleviate inflammation and oxidative stress induced by high-intensity exercise training in professional athletes.

Staphylococcus aureus Conquers Host by Hijacking Mitochondria via PFKFB3 in Epithelial Cells

Staphylococcus aureus persists within mammary epithelial cells for an extended duration, exploiting the host metabolic resources to facilitate replication. This study revealed a mechanism by which intracellular S aureus reprograms host metabolism, with PFKFB3 playing a crucial role in this process. Mechanistically, S aureus induced mitochondrial damage, leading to increased levels of mitochondrial reactive oxygen species and dysfunction in the electron transport chain. Moreover, S aureus shifted the balance of mitochondrial dynamics from fusion to fission, subsequently activating PINK1-PRKN-dependent mitophagy, causing loss of sirtuin 3 to stabilize hypoxic inducible factor 1α, and shifting the host metabolism toward enhanced glycolysis. The inhibition of PFKFB3 reversed the mitochondrial damage and degradation of sirtuin 3 induced by S aureus. Overall, our findings elucidate the mechanism by which S aureus reprograms host metabolism, thereby offering insights into the treatment of S aureus infection.

SENP3-FIS1 axis promotes mitophagy and cell survival under hypoxia

SUMOylation, the covalent attachment of the small ubiquitin-like modifier (SUMO) to target proteins, and its reversal, deSUMOylation by SUMO proteases like Sentrin-specific proteases (SENPs), are crucial for initiating cellular responses to hypoxia. However, their roles in subsequent adaptation processes to hypoxia such as mitochondrial autophagy (mitophagy) remain unexplored. Here, we show that general SUMOylation, particularly SUMO2/3 modification, suppresses mitophagy under both normoxia and hypoxia. Furthermore, we identify deSUMO2/3-ylation enzyme SENP3 and mitochondrial Fission protein 1 (FIS1) as key players in hypoxia-induced mitophagy (HIM), with SUMOylatable FIS1 acting as a crucial regulator for SENP3-mediated HIM regulation. Interestingly, we find that hypoxia promotes FIS1 SUMO2/3-ylation and triggers an interaction between SUMOylatable FIS1 and Rab GTPase-activating protein Tre-2/Bub2/Cdc16 domain 1 family member 17 (TBC1D17), which in turn suppresses HIM. Therefore, we propose a novel SUMOylation-dependent pathway where the SENP3-FIS1 axis promotes HIM, with TBC1D17 acting as a fine-tuning regulator. Importantly, the SENP3-FIS1 axis plays a protective role against hypoxia-induced cell death, highlighting its physiological significance, and hypoxia-inducible FIS1-TBC1D17 interaction is detectable in primary glioma stem cell-like (GSC) cultures derived from glioblastoma patients, suggesting its disease relevance. Our findings not only provide new insights into SUMOylation/deSUMOylation regulation of HIM but also suggest the potential of targeting this pathway to enhance cellular resilience under hypoxic stress.

Transfer and fates of damaged mitochondria: role in health and disease

Intercellular communication is pivotal in mediating the transfer of mitochondria from donor to recipient cells. This process orchestrates various biological functions, including tissue repair, cell proliferation, differentiation and cancer invasion. Typically, dysfunctional and depolarized mitochondria are eliminated through intracellular or extracellular pathways. Nevertheless, increasing evidence suggests that intercellular transfer of damaged mitochondria is associated with the pathogenesis of diverse diseases. This review investigates the prevalent triggers of mitochondrial damage and the underlying mechanisms of mitochondrial transfer, and elucidates the role of directional mitochondrial transfer in both physiological and pathological contexts. Additionally, we propose potential previously unknown mechanisms mediating mitochondrial transfer and explore their prospective roles in disease prevention and therapy.

A mechanistic systems biology model of brain microvascular endothelial cell signaling reveals dynamic pathway-based therapeutic targets for brain ischemia

Ischemic stroke is a significant threat to human health. Currently, there is a lack of effective treatments for stroke, and progress in new neuron-centered drug target development is relatively slow. On the other hand, studies have demonstrated that brain microvascular endothelial cells (BMECs) are crucial components of the neurovascular unit and play pivotal roles in ischemic stroke progression. To better understand the complex multifaceted roles of BMECs in the regulation of ischemic stroke pathophysiology and facilitate BMEC-based drug target discovery, we utilized a transcriptomics-informed systems biology modeling approach and constructed a mechanism-based computational multipathway model to systematically investigate BMEC function and its modulatory potential. Extensive multilevel data regarding complex BMEC pathway signal transduction and biomarker expression under various pathophysiological conditions were used for quantitative model calibration and validation, and we generated dynamic BMEC phenotype maps in response to various stroke-related stimuli to identify potential determinants of BMEC fate under stress conditions. Through high-throughput model sensitivity analyses and virtual target perturbations in model-based single cells, our model predicted that targeting succinate could effectively reverse the detrimental cell phenotype of BMECs under oxygen and glucose deprivation/reoxygenation, a condition that mimics stroke pathogenesis, and we experimentally validated the utility of this new target in terms of regulating inflammatory factor production, free radical generation and tight junction protection in vitro and in vivo. Our work is the first that complementarily couples transcriptomic analysis with mechanistic systems-level pathway modeling in the study of BMEC function and endothelium-based therapeutic targets in ischemic stroke.

PRKAA2-mediated mitophagy regulates oxygen consumption in yak renal tubular epithelial cells under chronic hypoxia

Hypoxic environments are significant factors in the induction of various kidney diseases and are closely associated with high oxygen consumption in the kidneys. Yaks live at high altitude for a long time, exhibit a unique ability to regulate kidney oxygen consumption, protecting them from hypoxia-induced damage. However, the mechanisms underlying the regulation of oxygen consumption in yak kidneys under hypoxic conditions remain unclear. To explore this hypoxia adaptation mechanism in yak kidneys, this study analyzed the oxygen consumption rate (OCR) of renal tubular epithelial cells (RTECs) under hypoxia. We found that the OCR and apoptosis rates of RTECs under chronic hypoxia (> 24 h) were lower than those under acute hypoxia (≤ 24 h). However, when oxygen consumption was promoted under chronic hypoxia, the apoptosis rate increased, indicating that reducing the cellular OCR is crucial for maintaining RTECs activity under hypoxia. High-throughput sequencing results showed that the mitophagy pathway is likely a key mechanism for inhibiting OCR of yak RTECs, with protein kinase AMP-activated catalytic subunit alpha 2 (PRKAA2) playing a significant role in this process. Further studies demonstrated that chronic hypoxia activates the mitophagy pathway, which inhibits oxidative phosphorylation (OXPHOS) while increasing glycolytic flux in yak RTECs. Conversely, when the mitophagy pathway was inhibited, there was an increase in the activity of OXPHOS enzymes and OCR. To further explore the role of PRKAA2 in the mitophagy pathway, we inhibited PRKAA2 expression under chronic hypoxia. Results showed that the downregulation of PRKAA2 decreased the expression of mitophagy-related proteins, such as p-FUNDC1/FUNDC1, LC3-II/LC3-I, BNIP3 and ULK1 while upregulating P62 expression. Additionally, there was an increase in the enzyme activities of Complex II, Complex IV, PDH, and SDH, which further promoted oxygen consumption in RTECs. These findings suggest that PRKAA2 mediated mitophagy under chronic hypoxia is crucial mechanism for reducing oxygen consumption in yak RTECs.

Constitutive HIF-1α Expression in the Epidermis Fuels Proliferation and Is Essential for Effective Barrier Formation

Epidermis is one of the most rapidly proliferating tissues in the body with high demands for adenosine triphosphate and cellular building blocks. In this study, we show that to meet these requirements, keratinocytes constitutively express HIF-1α, even in the presence of oxygen levels sufficient for HIF-1α hydroxylation. We previously reported that mice with severe epidermal mitochondrial dysfunction actually showed a hyperproliferative epidermis but rapidly died of systemic lactic acidosis and hypoglycemia, indicating excessive glycolysis. In this work, we interrogated HIF-1α function in glycolysis by its epidermal ablation combined with mitochondrial dysfunction, which resulted in decreased proliferation but even earlier lethality due to a severe barrier defect. Our data demonstrate that HIF-1α is indispensable for maintaining a high aerobic glycolytic flux necessary for supplying energy but also for synthetizing cellular building blocks such as lipids, which are both essential for proliferation as well as barrier formation. HIF-1α is stabilized in keratinocytes in the presence of oxygen by high levels of HIF-1α transcripts, low levels of prolyl-4-hydroxylases (PHD2 and PHD3), and a low cellular a-ketoglutarate/lactate ratio, likely inhibiting prolyl-4-hydroxylase activity. Our data suggest a key role for constitutive HIF-1α expression allowing a Warburg-like metabolism in healthy, highly proliferative keratinocytes, similar to that in tumor cells.

Gastrodin against oxidative stress-inflammation crosstalk via inhibiting mtDNA/TLR9 and JAK2/STAT3 signaling to ameliorate ischemic stroke injury

The pathway of Janus-activated kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) (termed as JAK2/STAT3) plays an active role in stroke-related inflammation induced by ischemic stress. Gastrodin, the primary compound in Gastrodia elata Bl, has been identified for its notable neuroprotective effects and demonstrated to ameliorate cerebral ischemia-reperfusion but its exact mechanisms governing this defense are still unclear. This study aims to investigate whether gastrodin can regulate mitochondrial function via the JAK2/STAT3 pathway to limit cerebral ischemia-reperfusion. In vivo, gastrodin significantly reduced infarct volume, improved neurobiological function, attenuated neuronal apoptosis, oxidative stress, mitochondrial impairment, mtDNA leakage, and inflammatory responses. At the cellular level, gastrodin administration rescued OGD/R-induced cell apoptosis, oxidative stress, and mitochondrial dysfunction. Mechanistically, gastrodin notably suppressed Toll-like receptor 9 (TLR9) expression, important for the recognition of disrupted endogenous DNA to produce inflammatory reactions. Furthermore, gastrodin mitigated inflammation by inhibiting JAK2/STAT3 signaling, influencing inflammatory factors to aggravate inflammation. Notably, the effects of gastrodin were abolished by Coumermycin A1 (C-A1), a JAK2 agonist, validating the role of JAK2/STAT3 signaling. In summary, gastrodin enhances the protective effect against mitochondrial damage in ischemic stroke by inhibiting JAK2/STAT3 signaling. Gastrodin is a possible therapy for cerebral ischemia.

The role of the KEAP1-NRF2 signaling pathway in form deprivation myopia guinea pigs

In recent years, the global prevalence of myopia has reached an unprecedented level, especially‌ in East Asia. Multitude of studies has shown that the etiology of myopia is complex. Some researchers have suggested that oxidative stress (OS) may contribute to myopia, although there are limited reports on the alterations of related signaling pathways. Notably, the Kelch-like ECH-associated protein 1 (KEAP1) -nuclear factor erythroid 2-related factor 2 (NRF2), which plays a significant role in regulating OS and the mechanism, has not been explored in myopia. To investigate the modulation of KEAP1-NRF2 signaling pathway and its downstream superoxide dismutase (SOD) during the development of form-deprivation myopia, three-week-old guinea pigs were randomly assigned to four groups: negative control (NC), self-control (SC), form-deprivation myopia (FDM), and FDM group treated with tert-butylhydroquinone (TBHQ). Spherical equivalent (SE) and axial length (AL) were measured by retinoscopy and A-scan ultrasound, respectively. The results revealed that TBHQ treatment decelerated the progression in SE and AL changes. Immunohistochemistry (IHC) assessed the distribution and expression of KEAP1, NRF2, and SOD. The results shown that they located in the retinal ganglion cells (RGC). Subsequently, retinal mRNA and protein expression levels of KEAP1, NRF2, and SOD were quantified using real-time polymerase chain reaction (RT-PCR) and Western blot (WB) analysis. The RT-PCR and WB results demonstrated that TBHQ could activate NRF2, induce KEAP1 degradation, and enhance the expression of the antioxidant SOD. In summary, the modulation of KEAP1-NRF2 and it downstream SOD expression could alter the retinal antioxidant capacity and influence the development of myopia.

Effects of cold stress on the blood-brain barrier in Plectropomus leopardus

BACKGROUND

The leopard coral grouper (Plectropomus leopardus) is a commercially valuable tropical marine fish species known to be sensitive to low temperatures. A comprehensive understanding of the molecular mechanisms governing its response to acute cold stress is of great importance. However, there is a relative scarcity of fundamental research on low-temperature tolerance in the leopard coral grouper.

METHODS

In this study, a cooling and rewarming experiment was conducted on 6-month-old leopard coral groupers. Within 24 h, we decreased the ambient temperature from 25 °C to 13 °C and subsequently allowed it to naturally return to 25 °C. During this process, a comprehensive investigation of serum hormone levels, enzyme activity, and brain transcriptome analysis was performed.

RESULTS

P. leopardus displayed a noticeable adaptive response to the initial temperature decrease by temporarily reducing its life activities. Our transcriptome analysis revealed that the differentially expressed genes (DEGs) were primarily concentrated in crucial pathways including the blood-brain barrier (BBB), inflammatory response, and coagulation cascade. In situ hybridization of claudin 15a (cldn15a), a key gene for BBB maintaining, further confirmed that exposure to low temperatures led to the disruption of the blood-brain barrier and stimulated a pronounced inflammatory reaction within the brain. Upon rewarming, there was a recovery of BBB integrity accompanied by the persistence of inflammation within the brain tissue.

CONCLUSIONS

Our study reveals the complex interactions between blood-brain barrier function, inflammation, and recovery in P. leopardus during short-term temperature drops and rewarming. These findings provide valuable insights into the physiological responses of this species under cold stress conditions.

Hypoxia and aging: molecular mechanisms, diseases, and therapeutic targets

Aging is a complex biological process characterized by the gradual decline of cellular functions, increased susceptibility to diseases, and impaired stress responses. Hypoxia, defined as reduced oxygen availability, is a critical factor that influences aging through molecular pathways involving hypoxia-inducible factors (HIFs), oxidative stress, inflammation, and epigenetic modifications. This review explores the interconnected roles of hypoxia in aging, highlighting how hypoxic conditions exacerbate cellular damage, promote senescence, and contribute to age-related pathologies, including cardiovascular diseases, neurodegenerative disorders, cancer, metabolic dysfunctions, and pulmonary conditions. By examining the molecular mechanisms linking hypoxia to aging, we identify key pathways that serve as potential therapeutic targets. Emerging interventions such as HIF modulators, antioxidants, senolytics, and lifestyle modifications hold promise in mitigating the adverse effects of hypoxia on aging tissues. However, challenges such as the heterogeneity of aging, lack of reliable biomarkers, and safety concerns regarding hypoxia-targeted therapies remain. This review emphasizes the need for personalized approaches and advanced technologies to develop effective antiaging interventions. By integrating current knowledge, this review provides a comprehensive framework that underscores the importance of targeting hypoxia-induced pathways to enhance healthy aging and reduce the burden of age-related diseases.

The mitochondrial Na+/Ca2+ exchanger NCLX is implied in the activation of hypoxia-inducible factors

Eukaryotic cells and organisms depend on oxygen for basic living functions, and they display a panoply of adaptations to situations in which oxygen availability is diminished (hypoxia). A number of these responses in animals are mediated by changes in gene expression programs directed by hypoxia-inducible factors (HIFs), whose main mechanism of stabilization and functional activation in response to decreased cytosolic oxygen concentration was elucidated two decades ago. Human acute responses to hypoxia have been known for decades, although their precise molecular mechanism for oxygen sensing is not fully understood. It is already known that a redox component, linked with reactive oxygen species (ROS) production of mitochondrial origin, is implied in these responses. We have recently described a mechanism by which the mitochondrial sodium/calcium exchanger, NCLX, participates in mitochondrial electron transport chain regulation and ROS production in response to acute hypoxia. Here we show that NCLX is also implied in the response to hypoxia mediated by the HIFs. By using a NCLX inhibitor and interference RNA we show that NCLX activity is necessary for HIF-α subunits stabilization in hypoxia and for HIF-1-dependent transcriptional activity. We also show that hypoxic mitochondrial ROS production is not required for HIF-1α stabilization under all circumstances, suggesting that the basal cytosolic redox state or other mechanism(s) could be operating in the NCLX-mediated response to hypoxia that operates through HIF-α stabilization. This finding provides a link between acute and medium-term responses to hypoxia, reinforcing a central role of mitochondrial cell signalling in the response to hypoxia.

Hydrogen Protects Mitochondrial Function by Increasing the Expression of PGC-1α and Ameliorating Myocardial Ischaemia-Reperfusion Injury

To investigate the application of H2 to alleviate cardiac ischaemia-reperfusion (I/R) injury in a PGC-1α-dependent manner. A rat in vitro myocardial I/R injury model was used, Western blot was used to detect the expression levels of apoptosis markers (Bax, cleaved caspase-3, Bcl2), inflammatory factors (IL-1β, TNF-α), mitochondrial fission (DRP1, MFF) and mitochondrial fusion (MFN1, MFN2, OPA1). HE staining was used to observe the effect of H2 on the myocardial tissue structure injured by I/R. Transmission electron microscopy (TEM) was used to observe the changes in the mitochondrial structure of myocardial tissue after I/R injury. Real-time quantitative PCR (qPCR) was used to detect the expression of PGC-1α in the myocardial tissue of rats after I/R injury and H2 treatment. H2 increases the expression level of PGC-1α, while the deletion of PGC-1α inhibited the therapeutic effect of H2. H2 can improve the changes of the myocardial tissue and mitochondrial structure caused by I/R injury. H2 treatment effectively inhibited the inflammatory response, and the loss of PGC-1α could inhibit the therapeutic effect of H2. The application of H2 can alleviate myocardial I/R injury, and the loss of PGC-1α weakens the protective effect of H2 on the I/R heart.

Early heart and skeletal muscle mitochondrial response to a moderate hypobaric hypoxia environment

In eukaryotic cells, aerobic energy is produced by mitochondria through oxygen uptake. However, little is known about the early mitochondrial responses to moderate hypobaric hypoxia (MHH) in highly metabolic active tissues. Here, we describe the mitochondrial responses to acute MHH in the heart and skeletal muscle. Rats were randomly allocated into a normoxia control group (n = 10) and a hypoxia group (n = 30), divided into three groups (0, 6, and 24 h post-MHH). The normoxia situation was recapitulated at the University of Granada, at 662 m above sea level. The MHH situation was performed at the High-Performance Altitude Training Centre of Sierra Nevada located in Granada at 2320 m above sea level. We found a significant increase in mitochondrial supercomplex assembly in the heart as soon as the animals reached 2320 m above sea level and their levels are maintained 24 h post-exposure, but not in skeletal muscle. Furthermore, in skeletal muscle, at 0 and 6 h, there was increased dynamin-related protein 1 (Drp1) expression and a significant reduction in Mitofusin 2. In conclusion, mitochondria from the muscle and heart respond differently to MHH: mitochondrial supercomplexes increase in the heart, whereas, in skeletal muscle, the mitochondrial pro-fission response is trigged. Considering that skeletal muscle was not actively involved in the ascent when the heart was beating faster to compensate for the hypobaric, hypoxic conditions, we speculate that the different responses to MHH are a result of the different energetic requirements of the tissues upon MHH. KEY POINTS: The heart and the skeletal muscle showed different mitochondrial responses to moderate hypobaric hypoxia. Moderate hypobaric hypoxia increases the assembly of the electron transport chain complexes into supercomplexes in the heart. Skeletal muscle shows an early mitochondrial pro-fission response following exposure to moderate hypobaric hypoxia.

Changes in reactive oxygen species and autofluorescence under hypoxia at the hippocampal CA3 area: Role of calcium and zinc influxes

Reactive oxygen species (ROS) have an important role in cellular biology, being involved, in a way that depends on their levels, in cell signaling processes or in oxidative stress, probably associated with neurodegenerative and other diseases. Most of the studies about ROS formation were performed in ischemic conditions, and thus, there is limited knowledge about ROS formation in less severe hypoxic conditions. This study investigates neuronal ROS generation and autofluorescence changes in hypoxic conditions, focusing on the involvement of calcium and zinc. Using hippocampal slices from Wistar rats, ROS production was monitored by the permeant fluorescent indicator H2DCFDA under different oxygenation levels. Moderate hypoxia (40% O2) led to a small ROS increase, while severe hypoxia (0% O2) showed a more pronounced rise. KCl-induced depolarization significantly enhanced ROS formation, particularly under severe hypoxia. Inhibition of NMDA receptors reduced ROS generation without affecting autofluorescence, while chelation of zinc ions decreased ROS production and increased flavin adenine dinucleotide (FAD) autofluorescence. These findings suggest that, in hypoxic conditions, ROS formation is mediated by calcium entry through NMDA receptors and also by zinc influxes. Thus, these ions play a crucial role in oxidative stress, which may be related with neurodegenerative diseases associated with ROS dysregulation.

Tile: Construction of a specific nanoprobe for scavenging ROS in hypobaric hypoxia induced brain injury of mice

The prevention and treatment of hypobaric hypoxia brain injury (HHBI) remains an unprecedented challenge due to the complex oxidative stress response at the damage site. In this study, RuCO phthalocyanine compound (RuPc) and bovine serum albumin (BSA) were self-assembled to obtain RuPc-BSA nanoparticles for HHBI therapy. As a nanoprobe carrying and storing carbon monoxide (CO), RuPc-BSA delivers CO to pathologically damaged areas of the brain. CO specifically attaches itself to the heme functional groups on mitochondria and restricts the source of reactive oxygen species (ROS) generation. RuPc-BSA nanoparticles have been demonstrated in vitro to exhibit amazing stability as well as remarkable scavenging activity on hydroxyl radical, superoxide anion, and hydrogen peroxide. In vivo experiments showed that ROS levels in the brain of HHBI rats pretreated with RuPc-BSA decreased significantly, and neuronal function and oxidative stress levels were alleviated. Western blot and qRT-RCR results indicated that RuPc-BSA restricted the protein levels of Keap1, whereas enhanced the gene and protein levels of Nrf2. This study demonstrated that RuPc-BSA can ameliorate HHBI of mice by scavenging ROS partly via activating Keap1/Nrf2 signaling pathway.

Topical hADSCs-HA Gel Promotes Skin Regeneration and Angiogenesis in Pressure Ulcers by Paracrine Activating PPARβ/δ Pathway

Background

Pressure ulcer is common in the bedridden elderly with high mortality and lack of effective treatment. In this study, human-adipose-derived-stem-cells-hyaluronic acid gel (hADSCs-HA gel) was developed and applied topically to treat pressure ulcers, of which efficacy and paracrine mechanisms were investigated through in vivo and in vitro experiments.

Methods

Pressure ulcers were established on the backs of C57BL/6 mice and treated topically with hADSCs-HA gel, hADSCs, hyaluronic acid, and normal saline respectively. The rate of wound closure was observed continuously during the following 14 days and the wound samples were obtained for Western blot, histopathology, immunohistochemistry, and proteomic analysis. Human dermal fibroblasts (HDFs) and human venous endothelial cells (HUVECs) under normal or hypoxic conditions were treated with conditioned medium of human ADSCs (ADSC-CM), then CCK-8, scratch test, tube formation, and Western blot were conducted to evaluate the paracrine effects of hADSCs and to explore the underlying mechanism.

Results

The in vivo data demonstrated that hADSCs-HA gel significantly accelerated the healing of pressure ulcers by enhancing collagen expression, angiogenesis, and skin proliferation. The in vitro data revealed that hADSCs strengthened the proliferation and wound healing capabilities of HDFs and HUVECs, meanwhile promoted collagen secretion and tube formation through paracrine mode. ADSC-CM was also proved to exert protective effects on hypoxic HDFs and HUVECs. Besides, the results of proteomic analysis and Western blot elucidated that lipid metabolism and PPARβ/δ pathway mediated the healing effect of hADSCs-HA gel on pressure ulcers.

Conclusion

Our research showed that topical application of hADSCs-HA gel played an important role in dermal regeneration and angiogenesis. Therefore, hADSCs-HA gel exhibited the potential as a novel stem-cell-based therapeutic strategy of treating pressure ulcers in clinical practices.

Exploring the research progression and evolutionary trends of lung ischemia-reperfusion injury: A bibliometric analysis from 1979 to 2023

BACKGROUND

Lung ischemia-reperfusion injury (LIRI) poses a significant challenge in various clinical scenarios. Despite extensive research on the pathogenesis and potential treatments of LIRI, there is a notable absence of bibliometric analysis.

MATERIALS AND METHODS

We summarized the results of LIRI research through two searches on the Web of Science, covering data from 1979 to 2023 with topic words "lung" and "reperfusion injury". The collected data were analyzed and visualized based on country, author(s), and keywords by bibliometric software. The keyword "programmed cell death" was further added to explore the hotspot of the LIRI research field.

RESULTS

The initial analysis of 1648 research articles showed a total of 40 countries and 7031 researchers were involved in the publications, with America being the most productive country in the research field of LIRI. Keyword analysis revealed that the evolving focus of LIRI research has progressively transitioned from, lung transplantation, primary graft dysfunction, inflammation, oxidative stress, and ex vivo lung perfusion to cell death. Subsequently, 212 publications specifically addressing programmed cell death (PCD) in LIRI were identified, which clarified the recent hotspot of the LIRI field.

CONCLUSION

With closer international cooperation and increasing research scale, the LIRI research focused mainly on the pathogenesis and potential therapeutic interventions for LIRI. PCD in LIRI is becoming a trending topic and will continue to be a hotspot in this field. Our study may offer valuable guidance for future research endeavors concerning LIRI.

Discovery of SIRT1-Activating Hydrogen Sulfide Donating Derivatives for Efficient Resistant of Myocardial Ischemic Injury

Activating SIRT1 or promoting SIRT1 expression are both protective against myocardial ischemia. Combining these approaches would be an effective strategy for treating ischemic heart disease. Herein, we identified lead compounds with SIRT1 activation activity through screening the natural product library, and five series of H2S donating derivatives were designed and synthesized. Among them, compound 17 exerted an effective cardioprotective effect in vitro and in vivo. The addition of H2S scavenger attenuated the protective activity, emphasizing the critical involvement of H2S in the myocardial ischemia process. Interestingly, 17 exhibited stronger direct SIRT1 activative ability and induced higher SIRT1 expression capability compared to the lead. Furthermore, 17 attenuates oxidative stress-induced cardiomyocytes apoptosis by activating the SIRT1-PGC1α signaling pathway. Our study validated the promising potential of activating SIRT1 and promoting SIRT1 expression through H2S to improve cardiomyocytes function, providing novel insights into the protective mechanisms during the progression of ischemic heart disease.

Optogenetic Control of the Mitochondrial Protein Import in Mammalian Cells

Mitochondria provide cells with energy and regulate the cellular metabolism. Almost all mitochondrial proteins are nuclear-encoded, translated on ribosomes in the cytoplasm, and subsequently transferred to the different subcellular compartments of mitochondria. Here, we developed OptoMitoImport, an optogenetic tool to control the import of proteins into the mitochondrial matrix via the presequence pathway on demand. OptoMitoImport is based on a two-step process: first, light-induced cleavage by a TEV protease cuts off a plasma membrane-anchored fusion construct in close proximity to a mitochondrial targeting sequence; second, the mitochondrial targeting sequence preceding the protein of interest recruits to the outer mitochondrial membrane and imports the protein fused to it into mitochondria. Upon reaching the mitochondrial matrix, the matrix processing peptidase cuts off the mitochondrial targeting sequence and releases the protein of interest. OptoMitoImport is available as a two-plasmid system as well as a P2A peptide or IRES sequence-based bicistronic system. Fluorescence studies demonstrate the release of the plasma membrane-anchored protein of interest through light-induced TEV protease cleavage and its localization to mitochondria. Cell fractionation experiments confirm the presence of the peptidase-cleaved protein of interest in the mitochondrial fraction. The processed product is protected from proteinase K treatment. Depletion of the membrane potential across the inner mitochondria membrane prevents the mitochondrial protein import, indicating an import of the protein of interest by the presequence pathway. These data demonstrate the functionality of OptoMitoImport as a generic system with which to control the post-translational mitochondrial import of proteins via the presequence pathway.

Beyond Cancer Cells: How the Tumor Microenvironment Drives Cancer Progression

Liver cancer represents a substantial global health challenge, contributing significantly to worldwide morbidity and mortality. It has long been understood that tumors are not composed solely of cancerous cells, but also include a variety of normal cells within their structure. These tumor-associated normal cells encompass vascular endothelial cells, fibroblasts, and various inflammatory cells, including neutrophils, monocytes, macrophages, mast cells, eosinophils, and lymphocytes. Additionally, tumor cells engage in complex interactions with stromal cells and elements of the extracellular matrix (ECM). Initially, the components of what is now known as the tumor microenvironment (TME) were thought to be passive bystanders in the processes of tumor proliferation and local invasion. However, recent research has significantly advanced our understanding of the TME's active role in tumor growth and metastasis. Tumor progression is now known to be driven by an intricate imbalance of positive and negative regulatory signals, primarily influenced by specific growth factors produced by both inflammatory and neoplastic cells. This review article explores the latest developments and future directions in understanding how the TME modulates liver cancer, with the aim of informing the design of novel therapies that target critical components of the TME.

CARM1 drives triple-negative breast cancer progression by coordinating with HIF1A

Coactivator-associated arginine methyltransferase 1 (CARM1) promotes the development and metastasis of estrogen receptor alpha (ERα)-positive breast cancer. The function of CARM1 in triple-negative breast cancer (TNBC) is still unclear and requires further exploration. Here, we report that CARM1 promotes proliferation, epithelial-mesenchymal transition, and stemness in TNBC. CARM1 is upregulated in multiple cancers and its expression correlates with breast cancer progression. Genome-wide analysis of CARM1 showed that CARM1 is recruited by hypoxia-inducible factor-1 subunit alpha (HIF1A) and occupy the promoters of CDK4, Cyclin D1, β-Catenin, HIF1A, MALAT1, and SIX1 critically involved in cell cycle, HIF-1 signaling pathway, Wnt signaling pathway, VEGF signaling pathway, thereby modulating the proliferation and invasion of TNBC cells. We demonstrated that CARM1 is physically associated with and directly interacts with HIF1A. Moreover, we found that ellagic acid, an inhibitor of CARM1, can suppress the proliferation and invasion of TNBC by directly inhibiting CDK4 expression. Our research has determined the molecular basis of CARM1 carcinogenesis in TNBC and its effective natural inhibitor, which may provide new ideas and drugs for cancer therapy.

Studies related to the enhanced the effect of 5-aminolevulinic acid-based photodynamic therapy combined with tirapazamine

OBJECTIVE

5-aminolevulinic acid (5-ALA) is a precursor of the photosensitizer Protoporphyrin IX (PpIX) and photodynamic therapy (PDT) with 5-ALA has been used in clinical practice. However, tumor cellular hypoxia severely affects the efficiency of photodynamic therapy. In this study, photodynamic therapy was combined with tirapazamine to investigate the effects of the combined intervention and the related mechanisms it may involve.

METHODS

Colony formation assays were used to demonstrate cell proliferation. Transwell assays were performed to observe the effect on cell invasion and metastasis after the corresponding intervention. DCFH-DA probe was used to detect the reactive oxygen species content. Flow cytometry was used to detect the effects of the interventions on apoptosis and cell cycle. The relevant pathways that may be involved are explored by examining the expression levels of the relevant proteins and genes.

RESULTS

Colony formation assays indicated that the combined intervention inhibited cell proliferation. Transwell assays demonstrated that PDT combined with TPZ effectively inhibited tumor cell invasion and metastasis. In addition, fluorescence intensity generated by DCFH-DA oxidation was detected indicating that the combined intervention increased the formation of reactive oxygen species. Flow cytometry clearly showed that the combination of PDT and TPZ further increased apoptosis and cell cycle arrest. The results of western blotting and qRT-PCR experiments confirmed that the combination therapy inhibited HIF-1α/VEGF axis and the PI3K/Akt/mTOR pathway activation.

CONCLUSION

5-ALA-PDT combined with TPZ can inhibit cell proliferation, increase apoptosis, and inhibit the PI3K/Akt/mTOR pathway, thus inhibiting tumor growth and metastasis and improving anti-cancer effects.