Abnormal Mitochondrial Function Research Articles

Loss of primary cilia promotes mitochondria-dependent apoptosis in thyroid cancer

The primary cilium is well-preserved in human differentiated thyroid cancers such as papillary and follicular carcinoma. Specific thyroid cancers such as Hürthle cell carcinoma, oncocytic variant of papillary thyroid carcinoma (PTC), and PTC with Hashimoto’s thyroiditis show reduced biogenesis of primary cilia; these cancers are often associated the abnormalities in mitochondrial function. Here, we examined the association between primary cilia and the mitochondria-dependent apoptosis pathway. Tg-Cre;Ift88flox/flox mice (in which thyroid follicles lacked primary cilia) showed irregularly dilated follicles and increased apoptosis of thyrocytes. Defective ciliogenesis caused by deleting the IFT88 and KIF3A genes from thyroid cancer cell lines increased VDAC1 oligomerization following VDAC1 overexpression, thereby facilitating upregulation of mitochondria-dependent apoptosis. Furthermore, VDAC1 localized with the basal bodies of primary cilia in thyroid cancer cells. These results demonstrate that loss-of-function of primary cilia results in apoptogenic stimuli, which are responsible for mitochondrial-dependent apoptotic cell death in differentiated thyroid cancers. Therefore, regulating primary ciliogenesis might be a therapeutic approach to targeting differentiated thyroid cancers.

Targeting Mitochondria by SS-31 Ameliorates the Whole Body Energy Status in Cancer- and Chemotherapy-Induced Cachexia.

Simple SummaryCancer cachexia is a debilitating syndrome, caused by both tumor growth and chemotherapy. The skeletal muscle is one of the main tissues affected during cachexia, presenting with altered metabolism and function, leading to progressive tissue wasting. In the current study we aimed at counteracting cachexia by pharmacologically improving metabolic function with the mitochondria-targeted compound SS-31. Experimental cancer cachexia was obtained using C26-bearing mice either receiving chemotherapy (oxaliplatin plus 5-fluorouracil) or not. SS-31 proved effective in rescuing some of the metabolic impairments imposed by both tumor and chemotherapy in the skeletal muscle and the liver, improving systemic energy control. Unfortunately, such effects were no longer present at late disease stages when refractory cachexia ensued. Overall, we provide evidence of potential new treatments targeting mitochondrial function in order to counteract or delay cancer cachexia.Objective: Cachexia is a complex metabolic syndrome frequently occurring in cancer patients and exacerbated by chemotherapy. In skeletal muscle of cancer hosts, reduced oxidative capacity and low intracellular ATP resulting from abnormal mitochondrial function were described. Methods: The present study aimed at evaluating the ability of the mitochondria-targeted compound SS-31 to counteract muscle wasting and altered metabolism in C26-bearing (C26) mice either receiving chemotherapy (OXFU: oxaliplatin plus 5-fluorouracil) or not. Results: Mitochondrial dysfunction in C26-bearing (C26) mice associated with alterations of cardiolipin fatty acid chains. Selectively targeting cardiolipin with SS-31 partially counteracted body wasting and prevented the reduction of glycolytic myofiber area. SS-31 prompted muscle mitochondrial succinate dehydrogenase (SDH) activity and rescued intracellular ATP levels, although it was unable to counteract mitochondrial protein loss. Progressively increased dosing of SS-31 to C26 OXFU mice showed transient (21 days) beneficial effects on body and muscle weight loss before the onset of a refractory end-stage condition (28 days). At day 21, SS-31 prevented mitochondrial loss and abnormal autophagy/mitophagy. Skeletal muscle, liver and plasma metabolomes were analyzed, showing marked energy and protein metabolism alterations in tumor hosts. SS-31 partially modulated skeletal muscle and liver metabolome, likely reflecting an improved systemic energy homeostasis. Conclusions: The results suggest that targeting mitochondrial function may be as important as targeting protein anabolism/catabolism for the prevention of cancer cachexia. With this in mind, prospective multi-modal therapies including SS-31 are warranted.

High glucose induces Drp1-mediated mitochondrial fission via the Orai1 calcium channel to participate in diabetic cardiomyocyte hypertrophy

Mitochondrial dysfunction and impaired Ca2+ handling are involved in the development of diabetic cardiomyopathy (DCM). Dynamic relative protein 1 (Drp1) regulates mitochondrial fission by changing its level of phosphorylation, and the Orai1 (Ca2+ release-activated calcium channel protein 1) calcium channel is important for the increase in Ca2+ entry into cardiomyocytes. We aimed to explore the mechanism of Drp1 and Orai1 in cardiomyocyte hypertrophy caused by high glucose (HG). We found that Zucker diabetic fat rats induced by administration of a high-fat diet develop cardiac hypertrophy and impaired cardiac function, accompanied by the activation of mitochondrial dynamics and calcium handling pathway-related proteins. Moreover, HG induces cardiomyocyte hypertrophy, accompanied by abnormal mitochondrial morphology and function, and increased Orai1-mediated Ca2+ influx. Mechanistically, the Drp1 inhibitor mitochondrial division inhibitor 1 (Mdivi-1) prevents cardiomyocyte hypertrophy induced by HG by reducing phosphorylation of Drp1 at serine 616 (S616) and increasing phosphorylation at S637. Inhibition of Orai1 with single guide RNA (sgOrai1) or an inhibitor (BTP2) not only suppressed Drp1 activity and calmodulin-binding catalytic subunit A (CnA) and phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) expression but also alleviated mitochondrial dysfunction and cardiomyocyte hypertrophy caused by HG. In addition, the CnA inhibitor cyclosporin A and p-ERK1/2 inhibitor U0126 improved HG-induced cardiomyocyte hypertrophy by promoting and inhibiting phosphorylation of Drp1 at S637 and S616, respectively. In summary, we identified Drp1 as a downstream target of Orai1-mediated Ca2+ entry, via activation by p-ERK1/2-mediated phosphorylation at S616 or CnA-mediated dephosphorylation at S637 in DCM. Thus, the Orai1–Drp1 axis is a novel target for treating DCM.

SIRT1 reduces epigenetic and non-epigenetic changes to maintain the quality of postovulatory aged oocytes in mice

Postovulatory oocyte aging has a major influence on the development potential of embryos. Many antioxidants can delay oocyte aging by regulating the expression of SIRT1. However, there is a lack of knowledge on SIRT1 function in postovulatory oocyte aging. In vitro transcribed RNA of Sirt1 was injected into fresh oocytes to investigate the function of SIRT1 during postovulatory oocyte aging. In the present study, SIRT1 was found to be down-regulated in aged oocytes compared with fresh oocytes. Meanwhile the intensity of acetylation of H3K9 (H3K9ac) and H3K4 methylation increased in postovulatory aged oocytes. After the oocytes were injected with SIRT1 and aged for 12 h, the intensity of H3K9ac and H3K4 methylation markedly decreased compared with controls. Furthermore, SIRT1 overexpression also reduced the aging-induced oocyte morphological changes and reactive oxygen species accumulation, maintained the spindle normal morphology and attenuated the aging-associated abnormalities of mitochondrial function. The role of SIRT1 in protecting oocyte aging was diminished when oocytes with overexpressed SIRT1 were cultured with SIRT1 inhibitor EX-527. Briefly, these present results show that SIRT1 not only reduced the non-epigenetic changes such as abnormal oocyte morphology, ROS accumulation, spindle defects and mitochondrial dysfunctions but also regulated the epigenetic changes in order to maintain the quality of postovulatory aged oocytes.

Rutin inhibits DRP1-mediated mitochondrial fission and prevents ethanol-induced hepatotoxicity in HepG2 cells and zebrafish

ABSTRACT Excessive alcohol consumption causes the cellular and tissue damage. The toxic metabolites of ethanol are harmful to multiple organ systems, such as the central nervous system, skeletal muscles, and liver, and cause alcohol-induced diseases like cancer, as well as induce hepatotoxicity, and alcoholic myopathy. Alcohol exposure leads to a surge in hepatic alcohol metabolism and oxygen consumption, a decrease in hepatic ATP, and the rapid accumulation of lipid within hepatocytes. Several pathologies are closely linked to defective mitochondrial dynamics triggered by abnormal mitochondrial function and cellular homeostasis, raising the possibility that novel drugs targeting mitochondrial dynamics may have therapeutic potential in restoring cellular homeostasis in ethanol-induced hepatotoxicity. Rutin is a phytochemical polyphenol known to protect cells from cytotoxic chemicals. We investigated the effects of rutin on mitochondrial dynamics induced by ethanol. We found that rutin enhances mitochondrial dynamics by suppressing mitochondrial fission and restoring the balance of the mitochondrial dynamics. Mitochondrial elongation following rutin treatment of ethanol exposed cells was accompanied by reduced DRP1 expression. These data suggest that rutin plays an important role in remodeling of mitochondrial dynamics to alleviate hepatic steatosis and enhance mitochondrial function and cell viability.

Impact of intravenous iron on cardiac and skeletal oxidative stress and cardiac mitochondrial function in experimental uraemia chronic kidney disease.

Introuction: Uraemia leads to changes in cardiac structure, metabolic remodeling and anaemia, key factors in the development of heart failure in patients with chronic kidney disease. Previous studies have identified abnormalities in mitochondrial function, potentially impairing energy provision and enhancing oxidative stress. This study characterised oxidant status and changes in mitochondrial function in uraemia and the impact of correcting anaemia via intravenous iron therapy. Methods: Experimental uraemia was induced in male Sprague-Dawley rats via a subtotal nephrectomy and parenteral iron administration given 6 weeks post-surgery. Oxidative stress from tissue samples was evaluated by measuring pro-oxidant activities and anti-oxidant capacities in both sham and uraemic animals with and without iron supplementation. Thiobarbituric acid-reactive substances (TBARS), aconitase activity and cardiolipin were measured. Mitochondrial function was assessed using the Seahorse XFp analyser on isolated mitochondria excised from cardiac tissue. Results: Oxidative stress in this uraemic model was increased in cardiac tissue (increased GSSG/GSH ratio, TBARS and increased activities of pro-oxidant enzymes). There was no impact on skeletal tissue. Parenteral iron ameliorated oxidative stress by enhancing the anti-oxidant defense system in cardiac tissue and skeletal tissue. Examination of respiratory reserve in cardiac mitochondria demonstrated that parenteral iron restored mitochondrial function. This experimental model of uraemia demonstrated a specific oxidative stress on the heart muscle without significant changes in skeletal oxidant status. Iron therapy improved anti-oxidant defence system, consequently reducing oxidative stress in the heart and skeletal tissue. There was an improvement in cardiac mitochondrial function. Conclusions: This experimental evidence indicates that iron therapy could reduce vulnerability to oxidative stress and potentially improve both cardiac and skeletal functional capacity from improvements in mitochondrial function.

Different Phenotypes Caused by the Unique Mutation in the Same Family with Mitochondrial Encephalomyopathy

Background and Objective: Mitochondrial encephalomyopathies represent a clinically heterogeneous group of disorders resulting from abnormal mitochondrial function. This study investigates the clinical and genetic characteristics of families with mitochondrial encephalomyopathy. Methods: The clinical manifestations, biopsy and gene detection were retrospectively analyzed for four probands with definitively diagnosed mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) from three families with MELAS and/or maternally inherited diabetes and deafness (MIDD). Results: The initial symptoms of probands were convulsive headache and/or epilepsy. The members of the three families also had diabetes, deafness, muscle weakness and short statures. Typical characteristics were indicated by muscle biopsy and gene detection in all. Conclusion: We reveal that the same family can have MIDD and MELAS cases, which clearly show that the unique mutation may cause different syndromes in one family. Neurologists should take into account more possibilities and phenotypes in screening and genetic counselling for the families of probands.

Different Phenotypes Caused by the Unique Mutation in the Same Family with Mitochondrial Encephalomyopathy

<p><strong>Background and Objective:</strong>  Mitochondrial encephalomyopathies represent a clinically heterogeneous group of disorders resulting from abnormal mitochondrial function. This study investigates the clinical and genetic characteristics of families with mitochondrial encephalomyopathy.</p>
 <p><strong>Methods: </strong> The clinical manifestations, biopsy and gene detection were retrospectively analyzed for four probands with definitively diagnosed mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) from three families with MELAS and/or maternally inherited diabetes and deafness (MIDD).</p>
 <p><strong>Results:</strong>  The initial symptoms of probands were convulsive headache and/or epilepsy. The members of the three families also had diabetes, deafness, muscle weakness and short statures. Typical characteristics were indicated by muscle biopsy and gene detection in all.</p>
 <p><strong>Conclusion:</strong>  We reveal that the same family can have MIDD and MELAS cases, which clearly show that the unique mutation may cause different syndromes in one family. Neurologists should take into account more possibilities and phenotypes in screening and genetic counselling for the families of probands.</p>

Do deficits in mitochondrial spare respiratory capacity contribute to neuropsychological changes seen in Alzheimer’s disease?

AbstractBackgroundIn clinical settings, AD is defined by characteristic deficits in neuropsychological testing supported by amyloid and tau biomarkers and neuroimaging abnormalities. The biological cause of neuropsychological changes is not established. Tau deposition correlates with, but does not fully account for all observed neuropsychological impairments. We have shown mitochondrial spare respiratory capacity (MRSC) is lowered in AD patient fibroblasts. This study investigates if fibroblast mitochondrial functional abnormalities correlate with neuropsychological/neuroimaging changes in AD.Method10 AD patient and 10 control fibroblast samples were taken via skin biopsy. Adenosine Triphosphate (ATP) and extracellular lactate were measured using luminescent and fluorescent protocols respectively. Mitochondrial membrane potential (MMP) was measured using tetramethylrhodamine dye. Mitochondrial respiration and glycolytic function were measured using a Seahorse XF Analyzer. In‐depth Neuropsychological profiling, and brain structural MRIs were undertaken on all participants. Correlations were performed between MMP, MRSC and neuropsychological/MRI AD markers.ResultReductions in delayed (p<0.0001) and immediate recall (p<0.0001), semantic fluency (p<0.0001), phonemic fluency (p=0.0033) and MMSE (p=0.0009) scores were seen in AD patients. After controlling for age, education and brain reserve; left hippocampal (p=0.001), left parietal (p=0.002), right parietal (p=0.001) and anterior medial prefrontal cortical (p=0.017) gray matter volumes were reduced in AD patients. Fibroblast metabolic markers showed a reduction in MMP (p=0.001), MRSC (p<0.0001), glycolytic reserve(p=0.05), and extracellular lactate (p<0.05) in AD patients. MRSC and MMP correlated significantly with immediate recall ([MRSC, p=0.0041],[MMP, p=0.0115]), delayed recall ([MRSC, p=0.0013],[MMP, p=0.0138]) and semantic memory ([MRSC, p=0.0039],[MMP, p=0.009]) tests. The correlations between MRSC and neuropsychological measures remained after controlling for age, education and brain reserve. No correlations were seen between grey matter volumes and fibroblast metabolism.ConclusionThis study highlights how in‐depth metabolic analysis of sporadic AD fibroblasts identifies functional abnormalities that correlate with neuropsychological features distinctive to AD. This work may also explain how some of the fundamental biological processes that are affected in Alzheimer’s disease may contribute to the neuropsychological profiles that define the condition.

Metabolic Profiling in Human Fibroblasts Enables Subtype Clustering in Glycogen Storage Disease.

Glycogen storage disease subtypes I and III (GSD I and GSD III) are monogenic inherited disorders of metabolism that disrupt glycogen metabolism. Unavailability of glucose in GSD I and induction of gluconeogenesis in GSD III modify energy sources and possibly, mitochondrial function. Abnormal mitochondrial structure and function were described in mice with GSD Ia, yet significantly less research is available in human cells and ketotic forms of the disease. We hypothesized that impaired glycogen storage results in distinct metabolic phenotypes in the extra- and intracellular compartments that may contribute to pathogenesis. Herein, we examined mitochondrial organization in live cells by spinning-disk confocal microscopy and profiled extra- and intracellular metabolites by targeted LC-MS/MS in cultured fibroblasts from healthy controls and from patients with GSD Ia, GSD Ib, and GSD III. Results from live imaging revealed that mitochondrial content and network morphology of GSD cells are comparable to that of healthy controls. Likewise, healthy controls and GSD cells exhibited comparable basal oxygen consumption rates. Targeted metabolomics followed by principal component analysis (PCA) and hierarchical clustering (HC) uncovered metabolically distinct poises of healthy controls and GSD subtypes. Assessment of individual metabolites recapitulated dysfunctional energy production (glycolysis, Krebs cycle, succinate), reduced creatinine export in GSD Ia and GSD III, and reduced antioxidant defense of the cysteine and glutathione systems. Our study serves as proof-of-concept that extra- and intracellular metabolite profiles distinguish glycogen storage disease subtypes from healthy controls. We posit that metabolite profiles provide hints to disease mechanisms as well as to nutritional and pharmacological elements that may optimize current treatment strategies.

Kidney epithelial targeted mitochondrial transcription factor A deficiency results in progressive mitochondrial depletion associated with severe cystic disease

Abnormal mitochondrial function is a well-recognized feature of acute and chronic kidney diseases. To gain insight into the role of mitochondria in kidney homeostasis and pathogenesis, we targeted mitochondrial transcription factor A (TFAM), a protein required for mitochondrial DNA replication and transcription that plays a critical part in the maintenance of mitochondrial mass and function. To examine the consequences of disrupted mitochondrial function in kidney epithelial cells, we inactivated TFAM in sine oculis-related homeobox 2-expressing kidney progenitor cells. TFAM deficiency resulted in significantly decreased mitochondrial gene expression, mitochondrial depletion, inhibition of nephron maturation and the development of severe postnatal cystic disease, which resulted in premature death. This was associated with abnormal mitochondrial morphology, a reduction in oxygen consumption and increased glycolytic flux. Furthermore, we found that TFAM expression was reduced in murine and human polycystic kidneys, which was accompanied by mitochondrial depletion. Thus, our data suggest that dysregulation of TFAM expression and mitochondrial depletion are molecular features of kidney cystic disease that may contribute to its pathogenesis.

Anti-Amnesic Effect of Walnut via the Regulation of BBB Function and Neuro-Inflammation in Aβ1-42-Induced Mice.

This study was conducted to assess the protective effect of walnut (Juglans regia L.) extract on amyloid beta (Aβ)1-42-induced institute of cancer research (ICR) mice. By conducting a Y-maze, passive avoidance, and Morris water maze tests with amyloidogenic mice, it was found that walnut extract ameliorated behavioral dysfunction and memory deficit. The walnut extract showed a protective effect on the antioxidant system and cholinergic system by regulating malondialdehyde (MDA) levels, superoxide dismutase (SOD) contents, reduced glutathione (GSH) contents, acetylcholine (ACh) levels, acetylcholinesterase (AChE) activity, and protein expression of AChE and choline acetyltransferase (ChAT). Furthermore, the walnut extract suppressed Aβ-induced abnormality of mitochondrial function by ameliorating reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and ATP contents. Finally, the walnut extract regulated the expression of zonula occludens-1 (ZO-1) and occludin concerned with blood–brain barrier (BBB) function, expression of tumor necrosis factor-alpha (TNF-α), tumor necrosis factor receptor 1 (TNFR1), phosphorylated c-Jun N-terminal kinase (p-JNK), phosphorylated nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (p-IκB), cyclooxygenase-2 (COX-2), and interleukin 1 beta (IL-1β), related to neuroinflammation and the expression of phosphorylated protein kinase B (p-Akt), caspase-3, hyperphosphorylation of tau (p-tau), and heme oxygenase-1 (HO-1), associated with the Aβ-related Akt pathway.

Nuclear-Encoded lncRNA MALAT1 Epigenetically Controls Metabolic Reprogramming in HCC Cells through the Mitophagy Pathway

Mitochondrial dysfunction is a metabolic hallmark of cancer cells. In search of molecular factors involved in this dysregulation in hepatocellular carcinoma (HCC), we found that the nuclear-encoded long noncoding RNA (lncRNA) MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) was aberrantly enriched in the mitochondria of hepatoma cells. Using RNA reverse transcription-associated trap sequencing (RAT-seq), we showed that MALAT1 interacted with multiple loci on mitochondrial DNA (mtDNA), including D-loop, COX2, ND3, and CYTB genes. MALAT1 knockdown induced alterations in the CpG methylation of mtDNA and in mitochondrial transcriptomes. This was associated with multiple abnormalities in mitochondrial function, including altered mitochondrial structure, low oxidative phosphorylation (OXPHOS), decreased ATP production, reduced mitophagy, decreased mtDNA copy number, and activation of mitochondrial apoptosis. These alterations in mitochondrial metabolism were associated with changes in tumor phenotype and in pathways involved in cell mitophagy, mitochondrial apoptosis, and epigenetic regulation. We further showed that the RNA-shuttling protein HuR and the mitochondria transmembrane protein MTCH2 mediated the transport of MALAT1 in this nuclear-mitochondrial crosstalk. This study provides the first evidence that the nuclear genome-encoded lncRNA MALAT1 functions as a critical epigenetic player in the regulation of mitochondrial metabolism of hepatoma cells, laying the foundation for further clarifying the roles of lncRNAs in tumor metabolic reprogramming.

Minocycline attenuates depressive-like behaviors in mice treated with the low dose of intracerebroventricular streptozotocin; the role of mitochondrial function and neuroinflammation.

Neuroinflammation and mitochondrial dysfunction are suggested as mechanisms which are implicated in the pathophysiology of depression. Streptozotocin (STZ) is known to produce immune-inflammatory responses and mitochondrial dysfunction in different types of animal models of disease (e.g. type-1 diabetes and Alzheimer's disease). Therefore, a single low dose of Streptozotocin (STZ; intracerebroventricular, i.c.v, 0.2mg/mouse) was used to induce an animal model of depression. The present study aims to investigate the effects of short (24h) and long (14days) exposure to minocycline on STZ-induced depressive-like behaviors (n = 6-8), hippocampal oxidative state biomarkers (n = 4), and the expression of hippocampal genes related to innate immunity (n = 3) in the hippocampus of male adult mice. In addition, the protective effects of different modes of minocycline (acute pretreatment (20mg/kg, 1h before STZ), acute post-treatment (20mg/kg, 24h after STZ), chronic pretreatment (5mg/kg/day for 14days before STZ), and chronic post-treatment (5mg/kg/day for 14days after STZ) were compared with the STZ effects. As the data showed, both short and long effects of STZ were associated with the depressive-like behaviors, abnormal mitochondrial function, and upregulation of neuroinflammatory genes in the hippocampus. Different modes of minocycline treatment could attenuate the negative impact of STZ on animals. The data suggested that minocycline at a human therapeutic dose (5mg/kg) had protective effects against acute cellular damage induced by oxidation and the consequent inflammatory responses.

CircRNA Role and circRNA-Dependent Network (ceRNET) in Asthenozoospermia.

The role of circRNA in reproduction is under investigation. CircRNAs are expressed in human testis, spermatozoa (SPZ), and seminal plasma. Their involvement in embryo development has also been suggested. Asthenozoospermia, a common cause of male infertility, is characterized by reduced or absent sperm motility in fresh ejaculate. While abnormal mitochondrial function, altered sperm tail, and genomic causes have been deeply investigated, the epigenetic signature of asthenozoospermic derived SPZ still remains unexplored. CircRNAs may take part in the repertoire of differentially expressed molecules in infertile men. Considering this background, we carried out a circRNA microarray, identifying a total of 9,138 transcripts, 22% of them novel based and 83.5% with an exonic structure. Using KEGG analysis, we evaluated the circRNA contribution in pathways related to mitochondrial function and sperm motility. In order to discriminate circRNAs with a differential expression in SPZ with differential morphological parameters, we separated sperm cells by Percoll gradient and analyzed their differential circRNA payload. A bioinformatic approach was then utilized to build a circRNA/miRNA/mRNA network. With the aim to demonstrate a dynamic contribution of circRNAs to the sperm epigenetic signature, we verified their modulation as a consequence of an oral amino acid supplementation, efficacious in improving SPZ motility.

P0851THE DIFFERENTIAL IMPACT OF INTRAVENOUS IRON IN A MODEL OF EXPERIMENTAL URAEMIA ON TISSUE MARKERS OF OXIDATIVE STRESS

Abstract Background and Aims Uraemia leads to changes in cardiac structure, metabolic remodelling and anaemia, key factors in the development of heart failure in patients with chronic kidney disease (CKD). Previous studies have identified abnormalities in mitochondrial function in experimental uraemia, potentially impairing energy provision and enhancing oxidative stress. The aim of this study was to characterise oxidant status and changes in mitochondrial function in uraemia and the impact of iron therapy. Method Experimental uraemia was induced in male Sprague-Dawley rats via a subtotal nephrectomy and parenteral iron administration at 6 weeks post-surgery (10mg/Kg body weight). Pro-oxidant activities and antioxidant capacities (oxidised glutathione (GSSG) relative to reduced (GSH)) in both sham and uraemic animals and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS) was measured. Mitochondrial function was assessed using the SEAHORSE analyser. Results Oxidative stress was increased in cardiac tissue (69% increase in GSSG/GSH ratio, 38% rise in TBARS and significantly (79%) upregulated NADPH oxidase activity. Glutathione peroxidase (GPx) and glutathione reductase (GR) activities were significantly increased by 30%. Iron reduced GSSG/GSH ratio and TBARS by 62% and 51% respectively. Iron therapy was also associated with significantly increased aconitase activity. Parenteral iron improved respiratory reserve in cardiac mitochondria and skeletal mitochondria suggests IV iron restores mitochondrial function. Conclusion Uraemia leads or oxidative stress and mitochondrial dysfunction in cardiac tissue. Iron therapy reduces oxidative stress and improves cardiac mitochondrial function. This might lead to reduced adverse cardiovascular outcomes in CKD.

Resveratrol protects the mitochondria from vitrification injury in mouse 2-cell embryos

Mitochondria play a key role in embryo development by providing energy. However, vitrification often causes mitochondrion damage of embryo, which further impairs embryo development. Therefore, the efficiency of embryo development after vitrification could be improved by protecting mitochondrial function from vitrification injury. The purpose of this study was to investigate the effects of resveratrol on mitochondrial damage after vitrification. The results showed that vitrification induced the abnormal mitochondrial distribution and damage mitochondrial function of mouse 2-cell embryos. However, co-culturing with resveratrol for 2 h could repair the abnormal mitochondrial distribution and mitochondrial dysfunction of embryos after vitrification. More than anything, the subsequent development ability of vitrified-thawed 2-cell embryos was significantly higher than that with no resveratrol treatment. In conclusion, resveratrol could protect the mitochondrial from injury caused by vitrification.

Downregulation of the GLP-1/CREB/adiponectin pathway is partially responsible for diabetes-induced dysregulated vascular tone and VSMC dysfunction

BackgroundThe dysfunction of vasculature is observed in diabetes and might be responsible for the increased incidence of vascular events. Previous studies indicated that supplementation of GLP-1 analogues is beneficial to the cardiovascular functions in diabetic patients, but the mechanisms are not clear. MethodsA type 1 diabetic model was constructed. Vascular constrictions were measured using wire myograph. Western blotting and quantitative PCR were adopted to analyze the expression profiles of key molecules. Mitochondrial functions were analyzed in both vascular tissues or vascular smooth muscle cells (VSMCs). Dual-luciferase reporter assay was used to investigate the mechanism of adiponectin regulation. ResultsIn this study, abnormal vascular hypertrophy and increased vascular tones were observed in both diabetic patients and animals. ROS productions were increased in vessels and VSMCs from diabetic patients and animals, and the ROS scavenger mitoTEMPO partially attenuated the abnormal vascular tones and hypertension. In addition, decreased GLP-1 levels were observed, while GLP-1 supplementation improved the mitochondrial functions and vascular tones. Furthermore, it was shown that GLP-1 supplementation enhanced adiponectin expressions, while adiponectin facilitated the phosphorylation of AMPK and Sirt1 expressions. Also, CREB phosphorylation was enhanced upon GLP-1 supplementation and promoted the transcriptions of adiponectin. Finally, CREB inhibition partially attenuated the effects of GLP-1 on mitochondrial functions and adiponectin expressions. ConclusionGLP-1 downregulation might be an important mechanism of abnormal mitochondrial function and vascular tone in diabetes. Targeting GLP-1/CREB/adiponectin axis might become a promising therapeutic strategy in alleviating diabetes-related cardiovascular dysfunctions.

Novel role of dynamin-related-protein 1 in dynamics of ER-lipid droplets in adipose tissue.

Dynamin-Related-Protein 1 (DRP1) critically regulates mitochondrial and peroxisomal fission in multicellular organisms. However, the impact of DRP1 on other organelles, especially its direct influence on ER functions remains largely unclear. Here, we report that DRP1 translocates to endoplasmic reticulum (ER) in response to β-adrenergic stimulation. To further investigate the function of DRP1 on ER-lipid droplet (LD) dynamics and the metabolic subsequences, we generated an adipose tissue-specific DRP1 knockout model (Adipo-Drp1flx/flx ). We found that the LDs in adipose tissues of Adipo-Drp1flx/flx mice exhibited more unilocular morphology with larger sizes, and formed less multilocular structures upon cold exposure. Mechanistically, we discovered that abnormal LD morphology occurs because newly generated micro-LDs fail to dissociate from the ER due to DRP1 ablation. Conversely, the ER retention of LDs can be rescued by the overexpressed DRP1 in the adipocytes. The alteration of LD dynamics, combined with abnormal mitochondrial and autophagy functions in adipose tissue, ultimately lead to abnormalities in lipid metabolism in Adipo-Drp1flx/flx mice.

The effect of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) severity on cellular bioenergetic function.

Myalgic encephalomyelitis/ Chronic fatigue syndrome (ME/CFS) has been associated with abnormalities in mitochondrial function. In this study we have analysed previous bioenergetics data in peripheral blood mononuclear cells (PBMCs) using new techniques in order to further elucidate differences between ME/CFS and healthy control cohorts. We stratified our ME/CFS cohort into two individual cohorts representing moderately and severely affected patients in order to determine if disease severity is associated with bioenergetic function in PBMCs. Both ME/CFS cohorts showed reduced mitochondrial function when compared to a healthy control cohort. This shows that disease severity does not correlate with mitochondrial function and even those with a moderate form of the disease show evidence of mitochondrial dysfunction. Equations devised by another research group have enabled us to calculate ATP-linked respiration rates and glycolytic parameters. Parameters of glycolytic function were calculated by taking into account respiratory acidification. This revealed severely affected ME/CFS patients to have higher rates of respiratory acidification and showed the importance of accounting for respiratory acidification when calculating parameters of glycolytic function. Analysis of previously published glycolysis data, after taking into account respiratory acidification, showed severely affected patients have reduced glycolysis compared to moderately affected patients and healthy controls. Rates of ATP-linked respiration were also calculated and shown to be lower in both ME/CFS cohorts. This study shows that severely affected patients have mitochondrial and glycolytic impairments, which sets them apart from moderately affected patients who only have mitochondrial impairment. This may explain why these patients present with a more severe phenotype.