Metabolic Mitochondrial Dysfunction Research Articles

Mitochondria-Associated Organelle Crosstalk in Myocardial Ischemia/Reperfusion Injury.

Organelle damage is a significant contributor to myocardial ischemia/reperfusion (I/R) injury. This damage often leads to disruption of endoplasmic reticulum protein regulatory programs and dysfunction of mitochondrial energy metabolism. Mitochondria and endoplasmic reticulum are seamlessly connected through the mitochondrial-associated endoplasmic reticulummembrane (MAM), which serves as a crucial site for the exchange of organelles and metabolites. However, there is a lack of reports regarding the communication of information and metabolites between mitochondria and related organelles, which is a crucial factor in triggering myocardial I/R damage. To address this research gap, this review described the role of crosstalk between mitochondria and the correlative organelles such as endoplasmic reticulum, lysosomal and nuclei involved in reperfusion injury of the heart. In summary, this review aims to provide a comprehensive understanding of the crosstalk between organelles in myocardial I/R injury, with the ultimate goal of facilitating the development of targeted therapies based on this knowledge.

Comprehensive analysis of cuproptosis-related genes in immune infiltration and development of a novel diagnostic model for acute kidney injury

Background Acute kidney injury (AKI) represents a diverse range of conditions characterized by high incidence and mortality rates, and it is mainly associated with immune-mediated mechanisms and mitochondrial metabolism dysfunction. Cuproptosis, a recently identified form of programmed cell death dependent on copper, is closely linked to mitochondrial respiration and contributes to various diseases. Our study aimed to investigate the involvement of cuproptosis-related genes (CRGs) in AKI. Methods Identification of CRGs was conducted using differential expression analysis, and subsequent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted using human sequencing profiles. Utilizing CIBERSORT algorithm, receiver operating characteristic (ROC) curve analysis, nomogram development, and decision curve analysis (DCA), the association among immune scores, CRGs, and the diagnostic value of these genes was explored. Results Notably, six CRGs (FDX1, DLD, DLAT, DBT, PDHA1, and ATP7A) were identified as significant differentiators between AKI and non-AKI groups. The ROC curve, based on these six genes, demonstrated an AUC value of 0.917, which was further validated using an additional dataset with an AUC value of 0.902. Nomogram and DCA further confirmed the accuracy of the model in predicting the risk of AKI. Conclusion This study elucidated the role of cuproptosis in AKI and revealed the association between CRGs and infiltrated immune cells through comprehensive bioinformatic techniques. The six-gene cuproptosis-related signature exhibited remarkable predictive efficiency for AKI.

Mitochondria in depression: The dysfunction of mitochondrial energy metabolism and quality control systems.

Depression is the most disabling neuropsychiatric disorder, causing difficulties in daily life activities and social interactions. The exact mechanisms of depression remain largely unclear. However, some studies have shown that mitochondrial dysfunction would play a crucial role in the occurrence and development of depression. To summarize the known knowledge about the role of mitochondrial dysfunction in the pathogenesis of depression. We review the recent literature， including 105 articles, to summarize the mitochondrial energy metabolism and quality control systems in the occurrence and development of depression. Some antidepressants which may exert their effects by improving mitochondrial function are also discussed. Impaired brain energy metabolism and (or) damaged mitochondrial quality control systems have been reported not only in depression patients but in animal models of depression. Although the classical antidepressants have not been specially designed to target mitochondria, the evidence suggests that many antidepressants may exert their effects by improving mitochondrial function. This brief review focuses on the findings that implicate mitochondrial dysfunction and the quality control systems as important etiological factors in the context of depressive disorders. It will help us to understand the various concepts of mitochondrial dysfunction in the pathogenesis of depression, and to explore novel and more targeted therapeutic approaches for depression.

Targeting dysfunctional mitochondrial metabolism of hepatocytes caused by hepatitis B virus (HBV) in the treatment of the chronic HBV infection- a narrative review

Mitochondria possess a significant part in generation of adenosine triphosphate (ATP), Reactive oxygen species (ROS), in addition to the controlling of the innate immune reactions along with apoptosis. Numerous viruses interfere with the mitochondrial actions for facilitating their replication along with result in cell injury. Hepatitis B virus(HBV) portrays a hepatotropic virus which possesses the capacity of resulting in robust liver diseases inclusive of cirrhosis in addition to Hepatocellular carcinoma(HCC).This virus further possesses the capacity of changing the mitochondrial working in addition to metabolism for facilitating its replication along with their continuation. Having earlier reviewed the part of generation besides the epigenetic controlling of the ccc DNA micro chromosome, the manner host as well as viral factors impact transcription besides if utilization of epigenome editing could be done for silencing HBV ccc DNA forever and why persistence of HBV takes place besides mitochondrial metabolism, mitophagy in ageing and role in fatty acid metabolism here we have concentrated on Hepatitis B virus(HBV) along with described the recent advancements in our acquisition of knowledge regarding the association amongst HBV in addition to mitochondrial metabolism. Here we conducted a narrative review utilizing search engine pubmed, Google scholar; web of science; embase; Cochrane review library utilizing the MeSH terms like Hepatitis B virus; mitochondrial metabolism; mitophagy; CD8+T cells; oxidative phosphorylation (OXPHOS);viral replication; viral persistence. We have detailed the recent advancements in the crosstalk HBV as well as mitochondrial metabolism in addition to its actions on HBV replication of addition to persistence as well as how utilization of this knowledge can help in treatment of HBV-add of before chronic Hepatitis B (CHB) infection.

Metabolic Bypass Rescues Aberrant S-nitrosylation-Induced TCA Cycle Inhibition and Synapse Loss in Alzheimer's Disease Human Neurons.

In Alzheimer's disease (AD), dysfunctional mitochondrial metabolism is associated with synaptic loss, the major pathological correlate of cognitive decline. Mechanistic insight for this relationship, however, is still lacking. Here, comparing isogenic wild-type and AD mutant human induced pluripotent stem cell (hiPSC)-derived cerebrocortical neurons (hiN), evidence is foundfor compromised mitochondrial energy in AD using the Seahorse platform to analyze glycolysis and oxidative phosphorylation (OXPHOS). Isotope-labeled metabolic flux experiments revealed a major block in activity in the tricarboxylic acid (TCA) cycle at the α-ketoglutarate dehydrogenase (αKGDH)/succinyl coenzyme-A synthetase step, metabolizing α-ketoglutarate to succinate. Associated with this block, aberrant protein S-nitrosylation of αKGDH subunits inhibited their enzyme function. This aberrant S-nitrosylation is documented not only in AD-hiN but also in postmortem human AD brains versus controls, as assessed by two separate unbiased mass spectrometry platforms using both SNOTRAP identification of S-nitrosothiols and chemoselective-enrichment of S-nitrosoproteins. Treatment with dimethyl succinate, a cell-permeable derivative of a TCA substrate downstream to the block, resulted in partial rescue of mitochondrial bioenergetic function as well as reversal of synapse loss in AD-hiN. These findings have therapeutic implications that rescue of mitochondrial energy metabolism can ameliorate synaptic loss in hiPSC-based models of AD.

A novel homozygous nonsense variant of AK7 is associated with multiple morphological abnormalities of the sperm flagella

Research QuestionWhat novel genetic factors are associated with multiple morphological abnormalities of the sperm flagella (MMAF), a specific type of oligoasthenoteratozoospermia that leads to male infertility? However, a complete understanding of the genetic etiology of MMAF remains elusive. DesignWhole-exome sequencing and Sanger sequencing were performed to identify potential gene variants. Immunoblotting and immunofluorescence were applied to confirm the relationship between mutated genes and disease phenotypes. ROS (reactive oxygen species) and apoptosis levels were measured to evaluate sperm mitochondrial function. Transmission electron microscopy and scanning electron microscopy were employed to observe sperm ultrastructure. ResultsA novel homozygous nonsense variant of AK7, c.1153A>T (p. Lys385*), was identified in two infertile siblings with asthenoteratozoospermia through whole-exome sequencing. Both immunoblotting and immunofluorescence assays showed a practically complete absence of AK7 in the patient's spermatozoa. Additionally, the individual with the novel AK7 variant exhibited a phenotype characterized by severe oxidative stress and apoptosis caused by mitochondrial metabolic dysfunction of spermatozoa. Notably, remarkable flagellar defects with multiple axonemes in uniflagellate spermatozoa, accompanied by mitochondrial vacuolization were observed, which has not been previously reported in patients with other AK7 variants. ConclusionsOur experimental findings in human subjects demonstrate that a novel identified homozygous nonsense variant of AK7 may potentially be associated with MMAF-related asthenoteratozoospermia. The observed functional associations between mitochondria and sperm flagellar assembly provide evidence for potential mutual regulation between AK7 and flagella-associated proteins during spermatogenesis.

Remodeling of Mitochondrial Metabolism by a Mitochondria-Targeted RNAi Nanoplatform for Effective Cancer Therapy.

Emerging evidence has demonstrated the significant contribution of mitochondrial metabolism dysfunction to promote cancer development and progression. Aberrant expression of mitochondrial genome (mtDNA)-encoded proteins widely involves mitochondrial metabolism dysfunction, and targeted regulation of their expression can be an effective strategy for cancer therapy, which however is challenged due to the protection by the mitochondrial double membrane. Herein, a mitochondria-targeted RNAi nanoparticle (NP) platform for effective regulation of mitochondrial metabolism and breast cancer (BCa) therapy is developed. This nanoplatform is composed of a hydrophilic polyethylene glycol (PEG) shell, a hydrophobic poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) core, and charged-mediated complexes of mitochondria-targeting and membrane-penetrating peptide amphiphile (MMPA) and small interfering RNA (siRNA) embedded in the core. After tumor accumulation and internalization by tumor cells, these NPs can respond to the endosomal pH to expose the MMPA/siRNA complexes, which can specifically transport siRNA into the mitochondria to down-regulate mtDNA-encoded protein expression (e.g., ATP6 and CYB). More importantly, because ATP6 down-regulation can suppress ATP production and enhance reactive oxygen species (ROS) generation to induce mitochondrial damage and mtDNA leakage into tumor tissues, the NPs can combinatorially inhibit tumor growth via suppressing ATP production and repolarizing tumor-associated macrophages (TAMs) into tumor-inhibiting M1-like macrophages by mtDNA.

Social isolation and breast cancer.

Although the role of life-stressors in breast cancer remains unclear, social isolation is consistently associated with increased breast cancer risk and mortality. Social isolation can be defined as loneliness or an absence of perceived social connections. In female mice and rats, social isolation is mimicked by housing animals one per cage. Social isolation causes many biological changes, of which an increase in inflammatory markers and disruptions in mitochondrial and cellular metabolism are commonly reported. It is not clear how the two traditional stress-induced pathways, i.e., hypothalamic-pituitary axis (HPA), resulting a release of glucocorticoids from the adrenal cortex, and autonomic nervous system (ANS), resulting a release of catecholamines from the adrenal medulla and post-ganglionic neurons, could explain the increased breast cancer risk in socially isolated individuals. For example, glucocorticoid receptor activation in estrogen receptor positive breast cancer cells inhibits their proliferation, and activation of β-adrenergic receptor (β-AR) in immature immune cells promotes their differentiation towards anti-tumorigenic T cells. However, activation of HPA and ANS pathways may cause a disruption in the brain-gut-microbiome axis, resulting gut dysbiosis. Gut dysbiosis, in turn, leads to an alteration in the production of bacterial metabolites, such as short chain fatty acids, causing a systemic low-grade inflammation and inducing dysfunction in mitochondrial and cellular metabolism. A possible causal link between social isolation -induced increased breast cancer risk and mortality and gut dysbiosis should be investigated, as it offers new tools to prevent breast cancer.

Mechanism of aconitine mediated neuronal apoptosis induced by mitochondrial calcium overload caused by MCU

Aconitine is a crucial toxic component in Chinese herbal medicines such as Aconitum, Aconitum coreanum, and Aconitum soongaricum. The poisoning symptoms of the central nervous system and cardiovascular system caused by it are relatively common in China, and there are many studies on cardiovascular system diseases caused by aconitine. However, the specific mechanism of neurotoxicity induced by aconitine is still unclear. This study explored the effect and mechanism of mitochondrial calcium uniporter on mitochondrial energy metabolism disorder in aconitine poisoning hippocampal neurons. The results showed that after treatment with 400μmol/L aconitine, mitochondrial energy metabolism was abnormal in rat hippocampal neuron cells, the expression of MCU in mitochondria was up-regulated, calcium overload in mitochondria, ATP production decreased, and mitochondrial membrane potential Changes, increased expression of the apoptosis gene Cleaved-Caspase-3. After treatment with the MCU agonist spermine, mitochondrial energy metabolism was significantly abnormal, and cell apoptosis was increased considerably. However, pretreatment with calcium ion channel inhibitor Ruthenium Red (RR) effectively promoted the generation of ATP, thereby improving mitochondrial energy metabolism disorders and reducing cell apoptosis. These results suggest that aconitine induces mitochondrial energy metabolism dysfunction in hippocampal neurons, which may be related to the increased expression of MCU.

S-Nitrosylation-mediated dysfunction of TCA cycle enzymes in synucleinopathy studied in postmortem human brains and hiPSC-derived neurons

A causal relationship between mitochondrial metabolic dysfunction and neurodegeneration has been implicated in synucleinopathies, including Parkinson disease (PD) and Lewy body dementia (LBD), but underlying mechanisms are not fully understood. Here, using human induced pluripotent stem cell (hiPSC)-derived neurons with mutation in the gene encoding α-synuclein (αSyn), we report the presence of aberrantly S-nitrosylated proteins, including tricarboxylic acid (TCA) cycle enzymes, resulting in activity inhibition assessed by carbon-labeled metabolic flux experiments. This inhibition principally affects α-ketoglutarate dehydrogenase/succinyl coenzyme-A synthetase, metabolizing α-ketoglutarate to succinate. Notably, human LBD brain manifests a similar pattern of aberrantly S-nitrosylated TCA enzymes, indicating the pathophysiological relevance of these results. Inhibition of mitochondrial energy metabolism in neurons is known to compromise dendritic length and synaptic integrity, eventually leading to neuronal cell death. Our evidence indicates that aberrant S-nitrosylation of TCA cycle enzymes contributes to this bioenergetic failure.

Lipin-1 deficiency deteriorates defect of fatty acid β-oxidation and lipid-related kidney damage in diabetic kidney disease

Diabetic lipo-toxicity is a fundamental pathophysiologic mechanism in DM and is now increasingly recognized a key determinant of DKD. Targeting lipid metabolic disorders is an important therapeutic strategy for the treatment of DM and its complications, including DKD. This study aimed to explore the molecular mechanism of lipid metabolic regulation in kidney, especially renal PTECs, and elucidate the role of lipid metabolic related molecule lipin-1 in diabetic lipid-related kidney damage. In this study, lipin-1-deficient db/db mouse model and STZ/HFD-induced T2DM mouse model were used to determine the effect of lipin-1 on DKD development. Then RPTCs and LPIN1 knockdown or overexpressed HK-2 cells induced by PA were used to investigate the mechanism. We found that the expression of lipin-1 increased early and then decreased in kidney during the progression of DKD. Glucose and lipid metabolic disorders and renal insufficiency were found in these 2 types of diabetic mouse models. Interestingly, lipin-1 deficiency might be a pathogenic driver of DKD-to-CKD transition, which could further accelerate the imbalance of renal lipid homeostasis, the dysfunction of mitochondrial and energy metabolism in PTECs. Mechanistically, lipin-1 deficiency resulted in aggravated PTECs injury to tubulointerstitial fibrosis in DKD by downregulating FAO via inhibiting PGC-1α/PPARα mediated Cpt1α/HNF4α signaling and upregulating SREBPs to promote fat synthesis. This study provided new insights into the role of lipin-1 as a regulator for maintaining lipid homeostasis in the kidney, especially PTECs, and its deficiency led to the progression of DKD.

Targeting Mitochondrial Metabolic Dysfunction in Pulmonary Hypertension: Toward New Therapeutic Approaches?

Pulmonary arterial hypertension (PAH) is a rare disease characterized by pulmonary vascular remodeling leading to right heart failure and death. To date, despite the three therapeutic approaches targeting the three major endothelial dysfunction pathways based on the prostacyclin, nitric oxide/cyclic guanosine monophosphate, and endothelin pathways, PAH remains a serious disease. As such, new targets and therapeutic agents are needed. Mitochondrial metabolic dysfunction is one of the mechanisms involved in PAH pathogenesis in part through the induction of a Warburg metabolic state of enhanced glycolysis but also through the upregulation of glutaminolysis, tricarboxylic cycle and electron transport chain dysfunction, dysregulation of fatty acid oxidation or mitochondrial dynamics alterations. The aim of this review is to shed light on the main mitochondrial metabolic pathways involved in PAH and to provide an update on the resulting interesting potential therapeutic perspectives.

Impact of sustained de novo lipogenesis on mitochondrial dysfunction and hepatocellular redox during fatty liver disease

Dysfunctional mitochondrial metabolism and sustained de novo lipogenesis are characteristic of non-alcoholic fatty liver disease (NAFLD), a common comorbidity of obesity and type 2 diabetes. We hypothesize that sustained de novo lipogenesis, through its biochemical relationships with mitochondria (e.g., tri-carboxylic acid (TCA) cycle) can contribute to dysfunctional oxidative flux during NAFLD. In study 1, male mice (C57BL/6JN) were fed either a low-fat (LF; 10% fat Kcal), high-fat (HF; 60% fat Kcal), or high-fructose/HF diet (HFr/HF; 34.9% fructose Kcal, 25% fat Kcal) for 24-wks. Liver mitochondria were utilized to determine oxygen consumption and were incubated in a buffer (for 5-min) to determine changes in TCA cycle intermediates, using gas chromatography-mass spectrometry (GC-MS). Plasma and liver samples were utilized for GC-MS based metabolomics and determination of gene and protein expression. In study 2, C57BL/6JN mice were provided 30% fructose in drinking water (FW) for 2-wks to induce hepatic de novo lipogenesis vs. mice given regular water (RW). Liver mitochondria were incubated in a buffer containing 1mM [ 13 C 3 ]pyruvate or 2.5mM [ 13 C 4 ]malate for 5-min. Isotopomer distribution of the TCA cycle intermediates were determined using GC-MS. Both HF and HFr/HF diets resulted in similar degrees of hepatic steatosis. However, lipogenic gene expression ( Scd1, Acyl, Fasn) and fasting plasma β-hydroxybutyrate levels were higher (p<0.001) in HFr/HF vs. HF group. Further, the feeding-to-fasting induction of genes involved in lipid oxidation ( Cpt1α, Lcad, Hmgcs2) was higher (p ≤0.01) in HFr/HF vs. HF livers. After 5-min of incubation, the HFr/HF liver mitochondria had higher (p<0.05) TCA cycle intermediates vs. the HF. The HFr/HF mitochondria also had higher expression of oxidative phosphorylation proteins and higher oxygen consumption rates (OCR), vs. the HF (p<0.05). In study 2, fructose in drinking water induced hepatic de novo lipogenesis. Induction of lipogenesis was also accompanied by higher mitochondrial OCR, higher reactive oxygen species, and higher TCA cycle metabolism (p<0.05). Gene expression of components of the mitochondrial nutrient shuttles ( SLC25A13, MPC1, MPC2, ME1) was upregulated in lipogenic livers (p<0.05). Incorporation of 13 C from [ 13 C 4 ]malate into pyruvate and α-ketoglutarate, indices of malic enzyme and TCA cycle activity, were higher (p<0.05) in lipogenic livers. Similarly, incorporation of 13 C from [ 13 C 3 ]pyruvate into aspartate and citrate, indices of pyruvate carboxylase and pyruvate dehydrogenase activity, were also higher (p<0.05) in lipogenic livers. These results demonstrate that the induction of several facets of mitochondrial oxidative metabolism and de novo lipogenesis accompany a carbohydrate-rich dietary milieu and NAFLD. Sustained induction of both de novo lipogenesis and mitochondrial oxidative function could contribute to the progression of metabolic dysfunction during NAFLD. National Institutes of Health R01 DK112865 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Predictive value of presepsin and acylcarnitines for severity and biliary drainage in acute cholangitis.

Bacteremia, which is a major cause of mortality in patients with acute cholangitis, induces hyperactive immune response and mitochondrial dysfunction. Presepsin is responsible for pathogen recognition by innate immunity. Acylcarnitines are established mitochondrial biomarkers. To clarify the early predictive value of presepsin and acylcarnitines as biomarkers of severity of acute cholangitis and the need for biliary drainage. Of 280 patients with acute cholangitis were included and the severity was stratified according to the Tokyo Guidelines 2018. Blood presepsin and plasma acylcarnitines were tested at enrollment by chemiluminescent enzyme immunoassay and ultra-high-performance liquid chromatography-mass spectrometry, respectively. The concentrations of presepsin, procalcitonin, short- and medium-chain acylcarnitines increased, while long-chain acylcarnitines decreased with the severity of acute cholangitis. The areas under the receiver operating characteristic curves (AUC) of presepsin for diagnosing moderate/severe and severe cholangitis (0.823 and 0.801, respectively) were greater than those of conventional markers. The combination of presepsin, direct bilirubin, alanine aminotransferase, temperature, and butyryl-L-carnitine showed good predictive ability for biliary drainage (AUC: 0.723). Presepsin, procalcitonin, acetyl-L-carnitine, hydroxydodecenoyl-L-carnitine, and temperature were independent predictors of bloodstream infection. After adjusting for severity classification, acetyl-L-carnitine was the only acylcarnitine independently associated with 28-d mortality (hazard ratio 14.396; P < 0.001) (AUC: 0.880). Presepsin concentration showed positive correlation with direct bilirubin or acetyl-L-carnitine. Presepsin could serve as a specific biomarker to predict the severity of acute cholangitis and need for biliary drainage. Acetyl-L-carnitine is a potential prognostic factor for patients with acute cholangitis. Innate immune response was associated with mitochondrial metabolic dysfunction in acute cholangitis.

Abstract 4237: Social isolation induces gut dysbiosis, mitochondrial metabolic dysfunction, and infiltration of tumor immunosuppressive cells: Do they explain enhanced mammary tumorigenesis

Abstract Social isolation (SI), are associated with increased mortality from many diseases, including breast cancer. Up to 41% of breast cancer patients are estimated to feel socially isolated when assessed between 6 months and 2 years following their cancer diagnosis. Since socially isolated breast cancer survivors are at a 64% higher risk of breast cancer-specific mortality than socially integrated survivors, the biological mechanisms which mediate the effects of SI need to be identified to prevent increased mortality. In a preclinical model, we found that SI caused recurrence of mammary cancers which had been treated with hormone therapy and thus led cancer cells to emerge from dormancy. We further found that mammary glands of SI rats exhibited upregulation of IL6/JAK/STAT3 signaling pathway and impaired oxidative phosphorylation (OXPHOS), compared with group housed (GH) rats. We investigated if these changes could be mediated through the gut-brain-axis. Stress can affect the gut microbiota, and the gut microbiota is critical for regulating the host immunity. In four separate experiments, the effect of SI on the gut microbiota composition was assessed in C57BL/6 mice that were either group housed or housed singly in SI for 4 weeks. In each study replicate, several differences in the gut microbiota composition were seen, but these differences were mostly unique to each experiment. Beta-diversity was increased in three of the four experiments in SI mice. Nevertheless, at the genus level, SI suppressed the abundance of Akkermansia in all four replicates and increased Acetatifactor in three of the four replicates. These two bacterial changes are expected to disrupt OXPHOS, perhaps by resulting a suppression in short-chain fatty acid production. Further, low Akkermansia and high Acetatifactor are expected to increase inflammation. Thus, it is possible that the changes in the composition of the gut microbiota of SI animals explain an increase in IL6 signaling and a suppression in OXPHOS in their mammary gland. We also have studied immune cells in the spleen in SI and GH mice. SI increased the frequency of pro-inflammatory CD4+RORy+ cells, and the immunosuppressive Treg cells (CD4+Foxp3+) and myeloid derived suppressor cells (PMN-MDSCs). SI also increased PD1 expression in Foxp3+ cells. In an on-going study, we found that fecal microbiota transplant (FMT) from SI mice increased E0771 mammary tumor growth in antibiotic treated GH recipient mice, compared with mice receiving FMT from GH mice. Whether the FMT also altered IL6 and OXPHOS signaling in the mammary glands and tumors of recipient mice is currently being investigated. Our findings suggest that social isolation may increase breast cancer through inducing gut dysbiosis. Citation Format: Fabia de Oliveira Andrade, Maddie McDermott, Lu Jin, Vivek Verma, Karla Andrade de Oliveira, Christopher Staley, Leena Hilakivi-Clarke. Social isolation induces gut dysbiosis, mitochondrial metabolic dysfunction, and infiltration of tumor immunosuppressive cells: Do they explain enhanced mammary tumorigenesis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4237.

Integrative analysis revealed that distinct cuprotosis patterns reshaped tumor microenvironment and responses to immunotherapy of colorectal cancer.

Cuprotosis is a novel form of programmed cell death that involves direct targeting of key enzymes in the tricarboxylic acid (TCA) cycle by excess copper and may result in mitochondrial metabolic dysfunction. However, whether cuprotosis may mediate the tumor microenvironment (TME) and immune regulation in colorectal cancer (CRC) remains unclear. Ten cuprotosis-related genes were selected and unsupervised consensus clustering was performed to identify the cuprotosis patterns and the correlated TME characteristics. Using principal component analysis, a COPsig score was established to quantify cuprotosis patterns in individual patients. The top 9 most important cuprotosis signature genes were analyzed using single-cell transcriptome data. Three distinct cuprotosis patterns were identified. The TME cell infiltration characteristics of three patterns were associated with immune-excluded, immune-desert, and immune-inflamed phenotype, respectively. Based on individual cuprotosis patterns, patients were assigned into high and low COPsig score groups. Patients with a higher COPsig score were characterized by longer overall survival time, lower immune cell as well as stromal infiltration, and greater tumor mutational burden. Moreover, further analysis demonstrated that CRC patients with a higher COPsig score were more likely to respond to immune checkpoint inhibitors and 5-fluorouracil chemotherapy. Single-cell transcriptome analysis indicated that cuprotosis signature genes recruited tumor-associated macrophages to TME through the regulation of TCA and the metabolism of glutamine and fatty acid, thus influencing the prognosis of CRC patients. This study indicated that distinct cuprotosis patterns laid a solid foundation to the explanation of heterogeneity and complexity of individual TME, thus guiding more effective immunotherapy as well as adjuvant chemotherapy strategies.

Mitochondrial damage in a Takotsubo syndrome-like mouse model mediated by activation of β-adrenoceptor-Hippo signaling pathway.

Takotsubo syndrome (TTS) is characterized by short-term contractile dysfunction with its mechanism undefined. We showed that activation of cardiac Hippo pathway mediates mitochondrial dysfunction and that stimulation of β-adrenoceptors (βAR) activates Hippo pathway. Here, we investigated the role of βAR-Hippo signaling in mediating mitochondrial dysfunction in isoproterenol (Iso)-induced TTS-like mouse model. Elderly postmenopausal female mice were administered with Iso (1.25 mg/kg/h for 23 h). Cardiac function was determined by serially echocardiography. At days 1 and 7 post-Iso exposure, mitochondrial ultrastructure and function were examined by electron microscopy and various assays. Alterations in cardiac Hippo pathway and effects of genetic inactivation of Hippo kinase (Mst1) on mitochondrial damage and dysfunction in the acute phase of TTS were investigated. Isoproterenol exposure induced acute increase in biomarkers of cardiac damage and ventricular contractile dysfunction and dilation. At day 1 post-Iso, we observed extensive abnormalities in mitochondrial ultrastructure, downregulation of mitochondrial marker proteins, and mitochondrial dysfunction evidenced by lower ATP content, increased lipid droplets, higher contents of lactate, and augmented reactive oxygen species (ROS). All changes were reversed by day 7. βAR stimulation led to activation of cardiac Hippo pathway with enhanced expression of Hippo kinase Mst1 and inhibitory YAP phosphorylation, as well as reduced nuclear YAP-TEAD1 interaction. In mice with cardiac expression of inactive mutant Mst1 gene, acute mitochondrial damage and dysfunction were mitigated. Stimulation of cardiac βAR activates Hippo pathway that mediates mitochondrial dysfunction with energy insufficiency and enhanced ROS, promoting acute but short-term ventricular dysfunction.NEW & NOTEWORTHY Takotsubo syndrome (TTS) is featured by activation of sympatho-β-adrenoceptor (βAR) system leading to acute loss of ventricular contractile performance. However, the molecular mechanism remains undefined. We demonstrated, in an isoproterenol-induced murine TTS-like model, extensive mitochondrial damage, metabolic dysfunction, and downregulated mitochondrial marker proteins, changes temporarily associated with cardiac dysfunction. Mechanistically, stimulation of βAR activated Hippo signaling pathway and genetic inactivation of Mst1 kinase ameliorated mitochondrial damage and metabolic dysfunction at the acute phase of TTS.

Abstract P6-05-16: Social isolation induces gut dysbiosis, mitochondrial metabolic dysfunction, and infiltration of tumor immunosuppressive cells: do they explain enhanced mammary tumorigenesis?

Abstract Inadequate social contacts and loneliness, often referred to as social isolation (SI), are associated with increased mortality from many diseases, including breast cancer. Up to 41% of breast cancer patients have been identified as feeling socially isolated. Moreover, socially isolated breast cancer survivors have a 43% higher risk of recurrence than socially integrated survivors. To prevent increased mortality, biological mechanisms which mediate the effects of SI on cancer need to be identified. One unexplored, but possible mechanism is through the gut microbiota. Through bidirectional interactions, the gut is affected by stress and the gut microbiota in turn can modulate stress response, host immunity and metabolism. Here we tested the hypothesis that SI induces gut dysbiosis. In our study, repeated in four separate experiments, adult female mice were divided into two groups – those kept group housed (GH, 4 mice per cage) and those housed singly in SI for 4 weeks. Several differences in the gut microbial family, genus and species levels were seen, but the differences were mostly unique to each of the four experiment. Beta-diversity was increased in three of the four studies in SI mice. Since beta-diversity is increased by aging, SI may accelerate the aging process. At the genus level, SI significantly suppressed the abundance of Akkermansia in all four studies and increased Acetatifactor in three studies. These two bacterial changes are expected to disrupt mitochondrial oxidative phosphorylation (OXPHOS), most likely by suppressing the short-chain fatty acid production. Further, low Akkermansia and high Acetatifactor are expected to increase inflammation. In a separate study, we discovered that SI impaired OXPHOS and activated inflammatory pathways in the mammary gland. We also have assessed immune cells in the spleen. SI increased the frequency of pro-inflammatory CD4+RORy+ cells, and the immunosuppressive Treg (CD4+Foxp3+) and PMN-MDSCs cells. In addition, SI increased PD1 expression in Foxp3+ cells, suggesting that anti-PD1 therapy might adversely affect socially isolated breast cancer patients by invigorating Treg cells. We are currently studying if the changes in the gut microbiota in SI mice are causally linked to their impaired mitochondrial metabolism, immunosuppression and increased mammary cancer mortality. We also plan to investigate if dietary modifications can reverse gut dysbiosis in SI mice and prevent their increased mortality from mammary cancer. Citation Format: Fabia de Oliveira Andrade, Lu Jin, Vivek Verma, Maddie McDermott, Chris Staley, Leena Hilakivi-Clarke. Social isolation induces gut dysbiosis, mitochondrial metabolic dysfunction, and infiltration of tumor immunosuppressive cells: do they explain enhanced mammary tumorigenesis? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-05-16.

CAMP agonist forskolin disrupts mitochondrial metabolism and induces senescence in human mesenchymal cells.

Adult-derived mesenchymal stem cells (MSCs) can be used in therapies for the treatment of various diseases. MSCs derived from aging tissues or long-term MSC cultures could have diminished therapeutic effects compared with MSCs derived from younger tissues, but the underlying mechanism has not been completely established. Dysfunction of energy metabolism is one of the main mechanisms underlying cell senescence. Although cyclic adenosine monophosphate (cAMP) is known to inhibit cell division and proliferation in vitro, its impact on MSC senescence has not been described. In this study, we used forskolin, an adenylate cyclase agonist and cAMP inducer, to disrupt metabolism in human adipose-derived MSCs and investigate the effects of metabolic dysfunction on MSC senescence. Treatment of human MSCs with forskolin resulted in senescence phenotypes, including reduced proliferation, cell-cycle arrest, and enhanced expression of the cell aging markers p16 and p21. Furthermore, the senescent MSCs exhibited increased adipogenesis capacity and decreased osteogenesis capacity as well as a senescence-associated secretory phenotype characterized by increased expression of several inflammatory factors. Forskolin-associated MSC senescence was mainly caused by oxidative stress-induced disruption of mitochondrial metabolism, and the senescent MSCs had high levels of reactive oxygen species and reduced sirtuin gene expression. Lastly, we found that cAMP inhibitor SQ22536 protects MSCs from forskolin-induced senescence and senescence-related-inflammatory-phenotype (SASP). Our results indicate that forskolin can cause senescence of human MSCs through oxidative stress-induced mitochondrial metabolic dysfunction, and thus the results provide a basis for developing strategies for improving the quality and efficacy of cultured MSCs for clinical use.

Multiple mitochondria-targeted components screened from Sini decoction improved cardiac energetics and mitochondrial dysfunction to attenuate doxorubicin-induced cardiomyopathy.

Rationale: Sini decoction (SND) is an efficient formula against DOX-induced cardiomyopathy (DCM), but the active ingredient combination (AIC) and mechanisms of SND remain unclear. Therefore, the present study aimed to identify the AIC and elucidate the underlying mechanism of AIC on DCM. Methods: The AIC were screened by a novel comprehensive two-dimensional cardiac mitochondrial membrane chromatography (CMMC)-TOFMS analysis system and further validated by cell viability, reactive oxygen species (ROS) generation, ATP level, and mitochondrial membrane potential in DOX-induced H9c2 cell injury model. Then, an integrated model of cardiac mitochondrial metabolomics and proteomics were applied to clarify the underlying mechanism in vitro. Results: The CMMC column lifespan was significantly improved to more than 10 days. Songorine (S), neoline, talatizamine, 8-gingerol (G) and isoliquiritigenin (I), exhibiting stronger retention on the first-dimension CMMC column, were screened to have protective effects against DOX cardiotoxicity in the H9c2 cell model. S, G and I were selected as an AIC from SND according to the bioactivity evaluation and the compatibility theory of SND. The combined in vitro use of S, G and I produced more profound therapeutic effects than any component used individually on increasing ATP levels and mitochondrial membrane potential and suppressing intracellular ROS production. Moreover, SGI attenuated DCM might via regulating mitochondrial energy metabolism and mitochondrial dysfunction. Conclusions: The provided scientific evidence to support that SGI combination from SND could be used as a prebiotic agent for DCM. Importantly, the proposed two-dimensional CMMC-TOFMS analytical system provides a high-throughput screening strategy for mitochondria-targeted compounds from natural products, which could be applied to other subcellular organelle models for drug discovery.