Project description:Mitochondrial DNA (mtDNA) encodes essential components of the respiratory chain and loss of mtDNA leads to mitochondrial dysfunction and neurodegeneration. Mitochondrial transcription factor A (TFAM) is an essential component of mtDNA replication and a regulator of mitochondrial copy number in cells. Studies have shown that TFAM knockdown leads to mitochondrial dysfunction and respiratory chain deficiencies. Using gene expression analysis, we aimed to investigate the effects of mtDNA dysfunction in the CNS at the molecular level. We used microarray analysis to investigate gene expression in cases of mitochondrial dysfunction in the CNS. RNA was purified from the late third instar larval CNS from control larvae, or larvae over-expressing mitochondrial transcription factor A (TFAM) in post-mitotic neurons using the neuron specific driver nsyb-Gal4. Three replicates are included for each condition.
Project description:Parkinson's disease (PD) is an adult-onset movement disorder of largely unknown etiology. We have previously shown that loss-of-function mutations of the mitochondrial protein kinase PINK1 (PTEN induced putative kinase 1) cause the recessive PARK6 variant of PD. Now we generated a PINK1 deficient mouse and observed several novel phenotypes: A progressive reduction of weight and of locomotor activity selectively for spontaneous movements occurred at old age. As in PD, abnormal dopamine levels in the aged nigrostriatal projection accompanied the reduced movements. Possibly in line with the PARK6 syndrome but in contrast to sporadic PD, a reduced lifespan, dysfunction of brainstem and sympathetic nerves, visible aggregates of M-NM-1-synuclein within Lewy bodies or nigrostriatal neurodegeneration were not present in aged PINK1-deficient mice. However, we demonstrate PINK1 mutant mice to exhibit a progressive reduction in mitochondrial preprotein import correlating with defects of core mitochondrial functions like ATP-generation and respiration. In contrast to the strong effect of PINK1 on mitochondrial dynamics in Drosophila melanogaster and in spite of reduced expression of fission factor Mtp18, we show reduced fission and increased aggregation of mitochondria only under stress in PINK1-deficient mouse neurons. Thus, aging Pink1M-bM-^HM-^R/M-bM-^HM-^R mice show increasing mitochondrial dysfunction resulting in impaired neural activity similar to PD, in absence of overt neuronal death. Transcriptome microarray data of Pink1-/- mouse brains in absence of a stressor, even at old age, show remarkably sparse dysregulations. See Gispert-S et al 2009 PLOS ONE. Factorial design comparing Pink1 knock-out mice with wild type littermates in three different tissues (striatum, midbrain, cerebellum at four different timepoints (6, 12, 14 weeks, and 18 month)
Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration. Insulin-treated T2DM subjects before and after 52 weeks of exercise training (T2DM_0 and T2DM_52), normoglycemic controls (NGT) and pre-diabetes subjects (IGT) and were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.
Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration.
Project description:The terminal stage of the complement activation pathways, the membrane attack complex (MAC), is upregulated in diabetic and rheumatoid arthritis patients, contributing pathologically by increasing inflammation. Previous research has highlighted that a sublytic dose of MAC can initiate NLRP3 inflammasome activation via calcium influx and loss of mitochondrial membrane potential. Here, we show that sublytic concentrations of MAC mediate a previously undescribed perturbation in cellular energy metabolism in human monocyte-derived macrophages, by phenotypic skewing towards glycolysis and upregulation of glycolysis-promoting genes. Sublytic MAC concentrations drive mitochondrial dysfunction, characterised by a fragmented mitochondrial morphology, loss of maximal respiratory response, depleted mitochondrial membrane potential as well as increased mitochondrial reactive oxygen species production. The consequences of these alterations in glycolytic metabolism and mitochondrial dysfunction lead to NLRP3 inflammasome activation, driving gasdermin D formation and IL-18 release. This novel link between sublytic MAC and immunometabolism, with direct consequences for downstream inflammatory processes, is important for development of novel therapeutics for areas where MAC may mediate disease.
Project description:The terminal stage in the complement activation pathways, the membrane attack complex (MAC), is upregulated in diabetic and rheumatoid arthritis patients, contributing pathologically by increasing inflammation. Previous research has highlighted that a sublytic dose of MAC can initiate NLRP3 inflammasome activation via calcium influx and loss of mitochondrial membrane potential. Here, we show that sublytic concentrations of MAC mediate a previously undescribed perturbation in cellular energy metabolism in human monocyte-derived macrophages, by phenotypic skewing towards glycolysis and upregulation of glycolysis-promoting genes. Sublytic MAC concentrations drive mitochondrial dysfunction, characterised by a fragmented mitochondrial morphology, loss of maximal respiratory response, depleted mitochondrial membrane potential as well as increased mitochondrial reactive oxygen species production. The consequences of these alterations in glycolytic metabolism and mitochondrial dysfunction lead to NLRP3 inflammasome activation, driving gasdermin D formation and IL-18 release. This novel link between sublytic MAC and immunometabolism, with direct consequences for downstream inflammatory processes, is important for development of novel therapeutics for areas where MAC may mediate disease.