Primary mitochondrial diseases: The intertwined pathophysiology of bioenergetic dysregulation, oxidative stress and neuroinflammation.

OBJECTIVES AND SCOPE: Primary mitochondrial diseases (PMDs) are rare genetic disorders resulting from mutations in genes crucial for effective oxidative phosphorylation (OXPHOS) that can affect mitochondrial function. In this review, we examine the bioenergetic alterations and oxidative stress observed in cellular models of primary mitochondrial diseases (PMDs), shedding light on the intricate complexity between mitochondrial dysfunction and cellular pathology. We explore the diverse cellular models utilized to study PMDs, including patient-derived fibroblasts, induced pluripotent stem cells (iPSCs) and cybrids. Moreover, we also emphasize the connection between oxidative stress and neuroinflammation. INSIGHTS: The central nervous system (CNS) is particularly vulnerable to mitochondrial dysfunction due to its dependence on aerobic metabolism and the correct functioning of OXPHOS. Similar to other neurodegenerative diseases affecting the CNS, individuals with PMDs exhibit several neuroinflammatory hallmarks alongside neurodegeneration, a pattern also extensively observed in mouse models of mitochondrial diseases. Based on histopathological analysis of postmortem human brain tissue and findings in mouse models of PMDs, we posit that neuroinflammation is not merely a consequence of neurodegeneration but a potential pathogenic mechanism for disease progression that deserves further investigation. This recognition may pave the way for novel therapeutic strategies for this group of devastating diseases that currently lack effective treatments. SUMMARY: In summary, this review provides a comprehensive overview of bioenergetic alterations and redox imbalance in cellular models of PMDs while underscoring the significance of neuroinflammation as a potential driver in disease progression.

Mitochondrial bioenergetics: coupling of transport to tubular mitochondrial metabolism.

PURPOSE OF REVIEW: Renal tubules have robust active transport and mitochondrial metabolism, which are functionally coupled to maintain energy homeostasis. Here, I review the current literature and our recent efforts to examine mitochondrial adaptation to different transport activities in renal tubules. RECENT FINDINGS: The advance of extracellular flux analysis (EFA) allows real-time assessments of mitochondrial respiration, glycolysis, and oxidation of energy substrates. We applied EFA assays to freshly isolated mouse proximal tubules, thick ascending limbs (TALs), and distal convoluted tubules (DCTs) and successfully differentiated their unique metabolic features. We found that TALs and DCTs adjusted their mitochondrial bioenergetics and biogenesis in response to acute and chronic alterations of transport activity. Based on the literature and our recent findings, I discuss working models and mechanisms underlying acute and chronic tubular adaptations to transport activity. The potential roles of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), AMP-activated protein kinase (AMPK), and uncoupling protein 2 (UCP2) are discussed. SUMMARY: Mitochondria in renal tubules are highly plastic to accommodate different transport activities. Understanding the mechanisms may improve the treatment of renal tubulopathies.

Uncovering the roles of Mycobacterium tuberculosis melH in redox and bioenergetic homeostasis: implications for antitubercular therapy.

Mycobacterium tuberculosis (Mtb), the pathogenic bacterium that causes tuberculosis, has evolved sophisticated defense mechanisms to counteract the cytotoxicity of reactive oxygen species (ROS) generated within host macrophages during infection. The melH gene in Mtb and Mycobacterium marinum (Mm) plays a crucial role in defense mechanisms against ROS generated during infection. We demonstrate that melH encodes an epoxide hydrolase and contributes to ROS detoxification. Deletion of melH in Mm resulted in a mutant with increased sensitivity to oxidative stress, increased accumulation of aldehyde species, and decreased production of mycothiol and ergothioneine. This heightened vulnerability is attributed to the increased expression of whiB3, a universal stress sensor. The absence of melH also resulted in reduced intracellular levels of NAD+, NADH, and ATP. Bacterial growth was impaired, even in the absence of external stressors, and the impairment was carbon source dependent. Initial MelH substrate specificity studies demonstrate a preference for epoxides with a single aromatic substituent. Taken together, these results highlight the role of melH in mycobacterial bioenergetic metabolism and provide new insights into the complex interplay between redox homeostasis and generation of reactive aldehyde species in mycobacteria. IMPORTANCE: This study unveils the pivotal role played by the melH gene in Mycobacterium tuberculosis and in Mycobacterium marinum in combatting the detrimental impact of oxidative conditions during infection. This investigation revealed notable alterations in the level of cytokinin-associated aldehyde, para-hydroxybenzaldehyde, as well as the redox buffer ergothioneine, upon deletion of melH. Moreover, changes in crucial cofactors responsible for electron transfer highlighted melH's crucial function in maintaining a delicate equilibrium of redox and bioenergetic processes. MelH prefers epoxide small substrates with a phenyl substituted substrate. These findings collectively emphasize the potential of melH as an attractive target for the development of novel antitubercular therapies that sensitize mycobacteria to host stress, offering new avenues for combating tuberculosis.

Insulin induces bioenergetic changes and alters mitochondrial dynamics in podocytes.

Diabetic nephropathy (DN) is one of the most frequent complications of diabetes. Early stages of DN are associated with hyperinsulinemia and progressive insulin resistance in insulin-sensitive cells, including podocytes. The diabetic environment induces pathological changes, especially in podocyte bioenergetics, which is tightly linked with mitochondrial dynamics. The regulatory role of insulin in mitochondrial morphology in podocytes has not been fully elucidated. Therefore, the main goal of the present study was to investigate effects of insulin on the regulation of mitochondrial dynamics and bioenergetics in human podocytes. Biochemical analyses were performed to assess oxidative phosphorylation efficiency by measuring the oxygen consumption rate (OCR) and glycolysis by measuring the extracellular acidification rate (ECAR). mRNA and protein expression were determined by real-time polymerase chain reaction and Western blot. The intracellular mitochondrial network was visualized by MitoTracker staining. All calculations were conducted using CellProfiler software. Short-term insulin exposure exerted inhibitory effects on various parameters of oxidative respiration and adenosine triphosphate production, and glycolysis flux was elevated. After a longer time of treating cells with insulin, an increase in mitochondrial size was observed, accompanied by a reduction of expression of the mitochondrial fission markers DRP1 and FIS1 and an increase in mitophagy. Overall, we identified a previously unknown role for insulin in the regulation of oxidative respiration and glycolysis and elucidated mitochondrial dynamics in human podocytes. The present results emphasize the importance of the duration of insulin stimulation for its metabolic and molecular effects, which should be considered in clinical and experimental studies of DN.

Boosting Energy Deprivation by Synchronous Interventions of Glycolysis and Oxidative Phosphorylation for Bioenergetic Therapy Synergetic with Chemodynamic/Photothermal Therapy.

Bioenergetic therapy is emerging as a promising therapeutic approach. However, its therapeutic effectiveness is restricted by metabolic plasticity, as tumor cells switch metabolic phenotypes between glycolysis and oxidative phosphorylation (OXPHOS) to compensate for energy. Herein, Metformin (MET) and BAY-876 (BAY) co-loaded CuFe2 O4 (CF) nanoplatform (CFMB) is developed to boost energy deprivation by synchronous interventions of glycolysis and OXPHOS for bioenergetic therapy synergetic with chemodynamic/photothermal therapy (CDT/PTT). The MET can simultaneously restrain glycolysis and OXPHOS by inhibiting hexokinase 2 (HK2) activity and damaging mitochondrial function to deprive energy, respectively. Besides, BAY blocks glucose uptake by inhibiting glucose transporter 1 (GLUT1) expression, further potentiating the glycolysis repression and thus achieving much more depletion of tumorigenic energy sources. Interestingly, the upregulated antioxidant glutathione (GSH) in cancer cells triggers CFMB degradation to release Cu+ /Fe2+ catalyzing tumor-overexpressed H2 O2 to hydroxyl radical (∙OH), both impairing OXPHOS and achieving GSH-depletion amplified CDT. Furthermore, upon near-infrared (NIR) light irradiation, CFMB has a photothermal conversion capacity to kill cancer cells for PTT and improve ∙OH production for enhanced CDT. In vivo experiments have manifested that CFMB remarkably suppressed tumor growth in mice without systemic toxicity. This study provides a new therapeutic modality paradigm to boost bioenergetic-related therapies.

High OXPHOS efficiency in RA-FUdr-differentiated SH-SY5Y cells: involvement of cAMP signalling and respiratory supercomplexes.

Neurons are highly dependent on mitochondria to meet their bioenergetic needs and understanding the metabolic changes during the differentiation process is crucial in the neurodegeneration context. Several in vitro approaches have been developed to study neuronal differentiation and bioenergetic changes. The human SH-SY5Y cell line is a widely used cellular model and several differentiation protocols have been developed to induce a neuron-like phenotype including retinoic acid (RA) treatment. In this work we obtained a homogeneous functional population of neuron-like cells by a two-step differentiation protocol in which SH-SY5Y cells were treated with RA plus the mitotic inhibitor 2-deoxy-5-fluorouridine (FUdr). RA-FUdr treatment induced a neuronal phenotype characterized by increased expression of neuronal markers and electrical properties specific to excitable cells. In addition, the RA-FUdr differentiated cells showed an enrichment of long chain and unsaturated fatty acids (FA) in the acyl chain composition of cardiolipin (CL) and the bioenergetic analysis evidences a high coupled and maximal respiration associated with high mitochondrial ATP levels. Our results suggest that the observed high oxidative phosphorylation (OXPHOS) capacity may be related to the activation of the cyclic adenosine monophosphate (cAMP) pathway and the assembly of respiratory supercomplexes (SCs), highlighting the change in mitochondrial phenotype during neuronal differentiation.

XQZ3, a Chlorella pyrenoidosa polysaccharide suppresses cancer progression by restraining mitochondrial bioenergetics via HSP90/AKT signaling pathway.

The mitochondria are known to exert significant influence on various aspects of cancer cell physiology. The suppression of mitochondrial function represents a novel avenue for the advancement of anti-cancer pharmaceuticals. The heat shock protein HSP90 functions as a versatile regulator of mitochondrial metabolism in cancer cells, rendering as a promising target for anticancer interventions. In this work, a novel acid polysaccharide named as XQZ3 was extracted from Chlorella pyrenoidosa and purified by DEAE-cellulose and gel-filtration chromatography. The structural characteristic of XQZ3 was evaluated by monosaccharides composition, methylation analysis, TEM, FT-IR, and 2D-NMR. It was found that XQZ3 with a molecular weight of 29.13 kDa was a complex branched polysaccharide with a backbone mainly composed of galactose and mannose. It exhibited good antitumor activity in vitro and in vivo by patient-derived 3D organoid models and patient-derived xenografts models. The mechanistic investigations revealed that XQZ3 specifically interacted with HSP90, impeding the activation of the HSP90/AKT/mTOR signaling cascade. This, in turn, led to the induction of mitochondrial dysfunction, autophagy, and apoptosis, ultimately resulting in the demise of cancer cells due to nutrient deprivation. This study offers a comprehensive theoretical foundation for the advancement of XQZ3, a novel polysaccharide inhibitor targeting HSP90, with potential as an effective therapeutic agent against cancer.

An adenosine derivative promotes mitochondrial supercomplexes reorganization and restoration of mitochondria structure and bioenergetics in a diethylnitrosamine-induced hepatocellular carcinoma model.

Hepatocellular carcinoma (HCC) progression is associated with dysfunctional mitochondria and bioenergetics impairment. However, no data about the relationship between mitochondrial supercomplexes (hmwSC) formation and ATP production rates in HCC are available. Our group has developed an adenosine derivative, IFC-305, which improves mitochondrial function, and it has been proposed as a therapeutic candidate for HCC. We aimed to determine the role of IFC-305 on both mitochondrial structure and bioenergetics in a sequential cirrhosis-HCC model in rats. Our results showed that IFC-305 administration decreased the number and size of liver tumors, reduced the expression of tumoral markers, and reestablished the typical architecture of the hepatic parenchyma. The livers of treated rats showed a reduction of mitochondria number, recovery of the mtDNA/nDNA ratio, and mitochondrial length. Also, IFC-305 increased cardiolipin and phosphatidylcholine levels and promoted hmwSC reorganization with changes in the expression levels of hmwSC assembly-related genes. IFC-305 in HCC modified the expression of several genes encoding elements of electron transport chain complexes and increased the ATP levels by recovering the complex I, III, and V activity. We propose that IFC-305 restores the mitochondrial bioenergetics in HCC by normalizing the quantity, morphology, and function of mitochondria, possibly as part of its hepatic restorative effect.

Role of macrophage bioenergetics in N-acetylcysteine-mediated mitigation of lung injury and oxidative stress induced by nitrogen mustard.

Nitrogen mustard (NM) is a toxic vesicant that causes acute injury to the respiratory tract. This is accompanied by an accumulation of activated macrophages in the lung and oxidative stress which have been implicated in tissue injury. In these studies, we analyzed the effects of N-acetylcysteine (NAC), an inhibitor of oxidative stress and inflammation on NM-induced lung injury, macrophage activation and bioenergetics. Treatment of rats with NAC (150 mg/kg, i.p., daily) beginning 30 min after administration of NM (0.125 mg/kg, i.t.) reduced histopathologic alterations in the lung including alveolar interstitial thickening, blood vessel hemorrhage, fibrin deposition, alveolar inflammation, and bronchiolization of alveolar walls within 3 d of exposure; damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage fluid protein and cells, was also reduced by NAC, along with oxidative stress as measured by heme oxygenase (HO)-1 and Ym-1 expression in the lung. Treatment of rats with NAC attenuated the accumulation of macrophages in the lung expressing proinflammatory genes including Ptgs2, Nos2, Il-6 and Il-12; macrophages expressing inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and tumor necrosis factor (TNF)α protein were also reduced in histologic sections. Conversely, NAC had no effect on macrophages expressing the anti-inflammatory proteins arginase-1 or mannose receptor, or on NM-induced increases in matrix metalloproteinase (MMP)-9 or proliferating cell nuclear antigen (PCNA), markers of tissue repair. Following NM exposure, lung macrophage basal and maximal glycolytic activity increased, while basal respiration decreased indicating greater reliance on glycolysis to generate ATP. NAC increased both glycolysis and oxidative phosphorylation. Additionally, in macrophages from both control and NM treated animals, NAC treatment resulted in increased S-nitrosylation of ATP synthase, protecting the enzyme from oxidative damage. Taken together, these data suggest that alterations in NM-induced macrophage activation and bioenergetics contribute to the efficacy of NAC in mitigating lung injury.

Bioenergetic signatures of neurodevelopmental regression.

Background: Studies have linked autism spectrum disorder (ASD) to physiological abnormalities including mitochondrial dysfunction. Mitochondrial dysfunction may be linked to a subset of children with ASD who have neurodevelopmental regression (NDR). We have developed a cell model of ASD which demonstrates a unique mitochondrial profile with mitochondrial respiration higher than normal and sensitive to physiological stress. We have previously shown similar mitochondrial profiles in individuals with ASD and NDR. Methods: Twenty-six ASD individuals without a history of NDR (ASD-NoNDR) and 15 ASD individuals with a history of NDR (ASD-NDR) were recruited from 34 families. From these families, 30 mothers, 17 fathers and 5 typically developing (TD) siblings participated. Mitochondrial respiration was measured in peripheral blood mononuclear cells (PBMCs) with the Seahorse 96 XF Analyzer. PBMCs were exposed to various levels of physiological stress for 1 h prior to the assay using 2,3-dimethoxy-1,4-napthoquinone. Results: ASD-NDR children were found to have higher respiratory rates with mitochondria that were more sensitive to physiological stress as compared to ASD-NoNDR children, similar to our cellular model of NDR. Differences in mitochondrial respiration between ASD-NDR and TD siblings were similar to the differences between ASD-NDR and ASD-NoNDR children. Interesting, parents of children with ASD and NDR demonstrated patterns of mitochondrial respiration similar to their children such that parents of children with ASD and NDR demonstrated elevated respiratory rates with mitochondria that were more sensitive to physiological stress. In addition, sex differences were seen in ASD children and parents. Age effects in parents suggested that mitochondria of older parents were more sensitive to physiological stress. Conclusion: This study provides further evidence that children with ASD and NDR may have a unique type of mitochondrial physiology that may make them susceptible to physiological stressors. Identifying these children early in life before NDR occurs and providing treatment to protect mitochondrial physiology may protect children from experiencing NDR. The fact that parents also demonstrate mitochondrial respiration patterns similar to their children implies that this unique change in mitochondrial physiology may be a heritable factor (genetic or epigenetic), a result of shared environment, or both.

Targeting mitochondrial bioenergetics by combination treatment with imatinib and dichloroacetate in human erythroleukemic K­562 and colorectal HCT­116 cancer cells.

Tumor malignant cells are characterized by dysregulation of mitochondrial bioenergetics due to the 'Warburg effect'. In the present study, this metabolic imbalance was explored as a potential target for novel cancer chemotherapy. Imatinib (IM) downregulates the expression levels of SCΟ2 and FRATAXIN (FXN) genes involved in the heme­dependent cytochrome c oxidase biosynthesis and assembly pathway in human erythroleukemic IM­sensitive K­562 chronic myeloid leukemia cells (K­562). In the present study, it was investigated whether the treatment of cancer cells with IM (an inhibitor of oxidative phosphorylation) separately, or together with dichloroacetate (DCA) (an inhibitor of glycolysis), can inhibit cell proliferation or cause death. Human K­562 and IM­chemoresistant K­562 chronic myeloid leukemia cells (K­562R), as well as human colorectal carcinoma cells HCT­116 (+/+p53) and (­/­p53, with double TP53 knock-in disruptions), were employed. Treatments of these cells with either IM (1 or 2 µM) and/or DCA (4 mΜ) were also assessed for the levels of several process biomarkers including SCO2, FXN, lactate dehydrogenase A, glyceraldehyde­3­phosphate dehydrogenase, pyruvate kinase M2, hypoxia inducing factor­1a, heme oxygenase­1, NF­κB, stem cell factor and vascular endothelial growth factor via western blot analysis. Computational network biology models were also applied to reveal the connections between the ten proteins examined. Combination treatment of IM with DCA caused extensive cell death (>75%) in K­562 and considerable (>45%) in HCT­116 (+/+p53) cultures, but less in K­562R and HCT­116 (­/­p53), with the latter deficient in full length p53 protein. Such treatment, markedly reduced reactive oxygen species levels, as measured by flow­cytometry, in K­562 cells and affected the oxidative phosphorylation and glycolytic biomarkers in all lines examined. These findings indicated, that targeting of cancer mitochondrial bioenergetics with such a combination treatment was very effective, although chemoresistance to IM in leukemia and the absence of a full length p53 in colorectal cells affected its impact.

The Interplay of Mitochondrial Bioenergetics and Dopamine Agonists as an Effective Disease-Modifying Therapy for Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurological ailment with a slower rate of advancement that is more common in older adults. The biggest risk factor for PD is getting older, and those over 60 have an exponentially higher incidence of this condition. The failure of the mitochondrial electron chain, changes in the dynamics of the mitochondria, and abnormalities in calcium and ion homeostasis are all symptoms of Parkinson's disease (PD). Increased mitochondrial reactive oxygen species (mROS) and an energy deficit are linked to these alterations. Levodopa (L-DOPA) is a medication that is typically used to treat most PD patients, but because of its negative effects, additional medications have been created utilizing L-DOPA as the parent molecule. Ergot and non-ergot derivatives make up most PD medications. PD is successfully managed with the use of dopamine agonists (DA). To get around the motor issues produced by L-DOPA, these dopamine derivatives can directly excite DA receptors in the postsynaptic membrane. In the past 10 years, two non-ergoline DA with strong binding properties for the dopamine D2 receptor (D2R) and a preference for the dopamine D3 receptor (D3R) subtype, ropinirole, and pramipexole (PPx) have been developed for the treatment of PD. This review covers the most recent research on the efficacy and safety of non-ergot drugs like ropinirole and PPx as supplementary therapy to DOPA for the treatment of PD.

Individual bioenergetic capacity as a potential source of resilience to Alzheimer's disease.

Impaired glucose uptake in the brain is one of the earliest presymptomatic manifestations of Alzheimer's disease (AD). The absence of symptoms for extended periods of time suggests that compensatory metabolic mechanisms can provide resilience. Here, we introduce the concept of a systemic 'bioenergetic capacity' as the innate ability to maintain energy homeostasis under pathological conditions, potentially serving as such a compensatory mechanism. We argue that fasting blood acylcarnitine profiles provide an approximate peripheral measure for this capacity that mirrors bioenergetic dysregulation in the brain. Using unsupervised subgroup identification, we show that fasting serum acylcarnitine profiles of participants from the AD Neuroimaging Initiative yields bioenergetically distinct subgroups with significant differences in AD biomarker profiles and cognitive function. To assess the potential clinical relevance of this finding, we examined factors that may offer diagnostic and therapeutic opportunities. First, we identified a genotype affecting the bioenergetic capacity which was linked to succinylcarnitine metabolism and significantly modulated the rate of future cognitive decline. Second, a potentially modifiable influence of beta-oxidation efficiency seemed to decelerate bioenergetic aging and disease progression. Our findings, which are supported by data from more than 9,000 individuals, suggest that interventions tailored to enhance energetic health and to slow bioenergetic aging could mitigate the risk of symptomatic AD, especially in individuals with specific mitochondrial genotypes.

Transport activity regulates mitochondrial bioenergetics and biogenesis in renal tubules.

Renal tubules are featured with copious mitochondria and robust transport activity. Mutations in mitochondrial genes cause congenital renal tubulopathies, and changes in transport activity affect mitochondrial morphology, suggesting mitochondrial function and transport activity are tightly coupled. Current methods of using bulk kidney tissues or cultured cells to study mitochondrial bioenergetics are limited. Here, we optimized an extracellular flux analysis (EFA) to study mitochondrial respiration and energy metabolism using microdissected mouse renal tubule segments. EFA detects mitochondrial respiration and glycolysis by measuring oxygen consumption and extracellular acidification rates, respectively. We show that both measurements positively correlate with sample sizes of a few centimeter-length renal tubules. The thick ascending limbs (TALs) and distal convoluted tubules (DCTs) predominantly utilize glucose/pyruvate as energy substrates, whereas proximal tubules (PTs) are significantly much less so. Acute inhibition of TALs' transport activity by ouabain treatment reduces basal and ATP-linked mitochondrial respiration. Chronic inhibition of transport activity by 2-week furosemide treatment or deletion of with-no-lysine kinase 4 (Wnk4) decreases maximal mitochondrial capacity. In addition, chronic inhibition downregulates mitochondrial DNA mass and mitochondrial length/density in TALs and DCTs. Conversely, gain-of-function Wnk4 mutation increases maximal mitochondrial capacity and mitochondrial length/density without increasing mitochondrial DNA mass. In conclusion, EFA is a sensitive and reliable method to investigate mitochondrial functions in isolated renal tubules. Transport activity tightly regulates mitochondrial bioenergetics and biogenesis to meet the energy demand in renal tubules. The system allows future investigation into whether and how mitochondria contribute to tubular remodeling adapted to changes in transport activity. Key points: A positive correlation between salt reabsorption and oxygen consumption in mammalian kidneys hints at a potential interaction between transport activity and mitochondrial respiration in renal tubules.Renal tubules are heterogeneous in transport activity and mitochondrial metabolism, and traditional assays using bulk kidney tissues cannot provide segment-specific information.Here, we applied an extracellular flux analysis to investigate mitochondrial respiration and energy metabolism in isolated renal tubules. This assay is sensitive in detecting oxygen consumption and acid production in centimeter-length renal tubules and reliably recapitulates segment-specific metabolic features.Acute inhibition of transport activity reduces basal and ATP-linked mitochondrial respirations without changing maximal mitochondrial respiratory capacity. Chronic alterations of transport activity further adjust maximal mitochondrial respiratory capacity via regulating mitochondrial biogenesis or non-transcriptional mechanisms.Our findings support the concept that renal tubular cells finely adjust mitochondrial bioenergetics and biogenesis to match the new steady state of transport activity.

Mitochondrial bioenergetics, metabolism, and beyond in pancreatic ß-cells and diabetes.

In Type 1 and Type 2 diabetes, pancreatic ß-cell survival and function are impaired. Additional etiologies of diabetes include dysfunction in insulin-sensing hepatic, muscle, and adipose tissues as well as immune cells. An important determinant of metabolic health across these various tissues is mitochondria function and structure. This review focuses on the role of mitochondria in diabetes pathogenesis, with a specific emphasis on pancreatic ß-cells. These dynamic organelles are obligate for ß-cell survival, function, replication, insulin production, and control over insulin release. Therefore, it is not surprising that mitochondria are severely defective in diabetic contexts. Mitochondrial dysfunction poses challenges to assess in cause-effect studies, prompting us to assemble and deliberate the evidence for mitochondria dysfunction as a cause or consequence of diabetes. Understanding the precise molecular mechanisms underlying mitochondrial dysfunction in diabetes and identifying therapeutic strategies to restore mitochondrial homeostasis and enhance ß-cell function are active and expanding areas of research. In summary, this review examines the multidimensional role of mitochondria in diabetes, focusing on pancreatic ß-cells and highlighting the significance of mitochondrial metabolism, bioenergetics, calcium, dynamics, and mitophagy in the pathophysiology of diabetes. We describe the effects of diabetes-related gluco/lipotoxic, oxidative and inflammation stress on ß-cell mitochondria, as well as the role played by mitochondria on the pathologic outcomes of these stress paradigms. By examining these aspects, we provide updated insights and highlight areas where further research is required for a deeper molecular understanding of the role of mitochondria in ß-cells and diabetes.

Alcohol Impairs Bioenergetics and Differentiation Capacity of Myoblasts from Simian Immunodeficiency Virus-Infected Female Macaques.

Alcohol misuse and HIV independently induce myopathy. We previously showed that chronic binge alcohol (CBA) administration, with or without simian immunodeficiency virus (SIV), decreases differentiation capacity of male rhesus macaque myoblasts. We hypothesized that short-term alcohol and CBA/SIV would synergistically decrease differentiation capacity and impair bioenergetic parameters in female macaque myoblasts. Myoblasts from naïve (CBA-/SIV-), vehicle [VEH]/SIV, and CBA/SIV (N = 4-6/group) groups were proliferated (3 days) and differentiated (5 days) with 0 or 50 mM ethanol (short-term). CBA/SIV decreased differentiation and increased non-mitochondrial oxygen consumption rate (OCR) versus naïve and/or VEH/SIV. Short-term alcohol decreased differentiation; increased maximal and non-mitochondrial OCR, mitochondrial reactive oxygen species (ROS) production, and aldolase activity; and decreased glycolytic measures, ATP production, mitochondrial membrane potential (ΔΨm), and pyruvate kinase activity. Mitochondrial ROS production was closely associated with mitochondrial network volume, and differentiation indices were closely associated with key bioenergetic health and function parameters. Results indicate that short-term alcohol and CBA non-synergistically decrease myoblast differentiation capacity. Short-term alcohol impaired myoblast glycolytic function, driving the bioenergetic deficit. Results suggest potentially differing mechanisms underlying decreased differentiation capacity with short-term alcohol and CBA, highlighting the need to elucidate the impact of different alcohol use patterns on myopathy.

Transketolase drives the development of aortic dissection by impairing mitochondrial bioenergetics.

AIM: Aortic dissection (AD) is a disease with rapid onset but with no effective therapeutic drugs yet. Previous studies have suggested that glucose metabolism plays a critical role in the progression of AD. Transketolase (TKT) is an essential bridge between glycolysis and the pentose phosphate pathway. However, its role in the development of AD has not yet been elucidated. In this study, we aimed to explore the role of TKT in AD. METHODS: We collected AD patients' aortic tissues and used high-throughput proteome sequencing to analyze the main factors influencing AD development. We generated an AD model using BAPN in combination with angiotensin II (Ang II) and pharmacological inhibitors to reduce TKT expression. The effects of TKT and its downstream mediators on AD were elucidated using human aortic vascular smooth muscle cells (HAVSMCs). RESULTS: We found that glucose metabolism plays an important role in the development of AD and that TKT is upregulated in patients with AD. Western blot and immunohistochemistry confirmed that TKT expression was upregulated in mice with AD. Reduced TKT expression attenuated AD incidence and mortality, maintained the structural integrity of the aorta, aligned elastic fibers, and reduced collagen deposition. Mechanistically, TKT was positively associated with impaired mitochondrial bioenergetics by upregulating AKT/MDM2 expression, ultimately contributing to NDUFS1 downregulation. CONCLUSION: Our results provide new insights into the role of TKT in mitochondrial bioenergetics and AD progression. These findings provide new intervention options for the treatment of AD.

Bioenergetic dysfunction in the pathogenesis of intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration is a frequent cause of low back pain and is the most common cause of disability. Treatments for symptomatic IVD degeneration, including conservative treatments such as analgesics, physical therapy, anti-inflammatories and surgeries, are aimed at alleviating neurological symptoms. However, there are no effective treatments to prevent or delay IVD degeneration. Previous studies have identified risk factors for IVD degeneration such as aging, inflammation, genetic factors, mechanical overload, nutrient deprivation and smoking, but metabolic dysfunction has not been highlighted. IVDs are the largest avascular structures in the human body and determine the hypoxic and glycolytic features of nucleus pulposus (NP) cells. Accumulating evidence has demonstrated that intracellular metabolic dysfunction is associated with IVD degeneration, but a comprehensive review is lacking. Here, by reviewing the physiological features of IVDs, pathological processes and metabolic changes associated with IVD degeneration and the functions of metabolic genes in IVDs, we highlight that glycolytic pathway and intact mitochondrial function are essential for IVD homeostasis. In degenerated NPs, glycolysis and mitochondrial function are downregulated. Boosting glycolysis such as HIF1α overexpression protects against IVD degeneration. Moreover, the correlations between metabolic diseases such as diabetes, obesity and IVD degeneration and their underlying molecular mechanisms are discussed. Hyperglycemia in diabetic diseases leads to cell senescence, the senescence-associated phenotype (SASP), apoptosis and catabolism of extracellualr matrix in IVDs. Correcting the global metabolic disorders such as insulin or GLP-1 receptor agonist administration is beneficial for diabetes associated IVD degeneration. Overall, we summarized the recent progress of investigations on metabolic contributions to IVD degeneration and provide a new perspective that correcting metabolic dysfunction may be beneficial for treating IVD degeneration.

A bioenergetically-active ploy (glycerol sebacate)-based multiblock hydrogel improved diabetic wound healing through revitalizing mitochondrial metabolism.

Diabetic wounds impose significant burdens on patients' quality of life and healthcare resources due to impaired healing potential. Factors like hyperglycemia, oxidative stress, impaired angiogenesis and excessive inflammation contribute to the delayed healing trajectory. Mounting evidence indicates a close association between impaired mitochondrial function and diabetic complications, including chronic wounds. Mitochondria are critical for providing energy essential to wound healing processes. However, mitochondrial dysfunction exacerbates other pathological factors, creating detrimental cycles that hinder healing. This study conducted correlation analysis using clinical specimens, revealing a positive correlation between mitochondrial dysfunction and oxidative stress, inflammatory response and impaired angiogenesis in diabetic wounds. Restoring mitochondrial function becomes imperative for developing targeted therapies. Herein, we synthesized a biodegradable poly (glycerol sebacate)-based multiblock hydrogel, named poly (glycerol sebacate)-co-poly (ethylene glycol)-co-poly (propylene glycol) (PEPGS), which can be degraded in vivo to release glycerol, a crucial component in cellular metabolism, including mitochondrial respiration. We demonstrate the potential of PEPGS-based hydrogels to improve outcomes in diabetic wound healing by revitalizing mitochondrial metabolism. Furthermore, we investigate the underlying mechanism through proteomics analysis, unravelling the regulation of ATP and nicotinamide adenine dinucleotide metabolic processes, biosynthetic process and generation during mitochondrial metabolism. These findings highlight the therapeutic potential of PEPGS-based hydrogels as advanced wound dressings for diabetic wound healing.

Alcohol and its metabolites dysregulate cellular bioenergetics and induce oxidative and endoplasmic reticulum stress in primary human bronchial epithelial cells.

BACKGROUND: Chronic alcohol consumption/misuse is a significant risk factor for pneumonia and lung infection leading to the development of chronic pulmonary disorders such as chronic obstructive pulmonary disease (COPD) and lung fibrosis. In this study, we sought to delineate the mechanism of alcohol-associated lung disease. We did so by measuring in vitro mitochondrial, endoplasmic reticulum (ER) oxidative stress in human bronchial epithelial cells (hBECs) treated with ethanol and its oxidative (acetaldehyde) and nonoxidative (fatty acid ethyl esters or FAEEs) metabolites. METHODS: Primary hBECs from a normal subject were treated with relevant concentrations of ethanol and its metabolites and incubated at 37°C for 24 h. Viability and cytotoxicity were determined using cell viability and lactate dehydrogenase (LDH) assay kits, respectively. Oxidized glutathione (GSSG) and reduced glutathione (GSH) were measured by colorimetric reaction, and 4-hydroxynenonal (4HNE) by immunohistochemistry. Endoplasmic reticulum stress and dysregulated cellular bioenergetics were determined by western blot analysis. Mitochondrial stress and real-time ATP production rates were determined using a Seahorse Extracellular Flux analyzer. Amelioration of ethanol-induced oxidative/ER stress and mitochondrial energetics was determined using an AMPKα agonist. RESULTS: Human bronchial epithelial cells treated with ethanol, acetaldehyde, and FAEEs showed a concentration-dependent increase in the secretion of LDH, oxidative/ER stress, deactivation of AMPKα phosphorylation and mitochondrial stress (decreased spare respiratory capacity) with concomitant decreases in mitochondrial and glycolytic ATP production rates. FAEEs caused greater cytotoxicity, ER stress, and dysregulated cellular bioenergetics than those ethanol and its oxidative metabolite. AMPKα agonist-pretreated cells significantly ameliorated ethanol-induced oxidative/ER stress, deactivation of AMPKα, and dysregulated cellular bioenergetics. CONCLUSIONS: Findings of this study suggest that ethanol and its metabolites contribute to cytotoxicity, oxidative/ER stress, and dysregulation of cellular bioenergetics in hBECs. The attenuation of ethanol-induced ER/oxidative stress and mitochondrial respiration by an AMPKα agonist may reflect a potential for it to be developed as a therapeutic agent for chronic alcohol-associated lung disease.