Project description:Muscle tissue was longitudinally characterized histologically for electron transport function by staining 1mm of quadriceps muscle at 70 micron intervals for the activities of two complexes in the mitochondrial electron transport chain, Cytochrome C Oxidase and Succinate Dehydrogenase. Unstained serial cryosections were prepared for Laser Capture Microdissection. Target cells from the serial sections were isolated and pooled for RNA extraction, amplification and hybridization on Affymetrix microarrays. We selected homogeneous populations of muscle fibers for expression profiling based upon the presence/absence of electron transport dysfunction caused by the somatic accumulation of mitochondrial DNA deletion mutations. The design of this experiment is limited by the source tissue which is individually identified cells harboring intracellular clonal expansions of mitochondrial DNA deletion mutations. These unique and rare cells were identified in rat Vastus lateralis tissue in an aged 36-month old F344xBN F1 hybrid rat by exhaustive serial sectioning and subsequent histological characterization. Unstained serial sections where isolated by LCM and the purified RNA was amplified by 2 rounds of RNA based transcription prior to fragmentation and hybridization on rat genome affymetrix chips. Two populations of cells were analyzed, Electron transport deficient and normal control cells from the same animal.
Project description:Muscle tissue was longitudinally characterized histologically for electron transport function by staining 1mm of quadriceps muscle at 70 micron intervals for the activities of two complexes in the mitochondrial electron transport chain, Cytochrome C Oxidase and Succinate Dehydrogenase. Unstained serial cryosections were prepared for Laser Capture Microdissection. Target cells from the serial sections were isolated and pooled for RNA extraction, amplification and hybridization on Affymetrix microarrays. We selected homogeneous populations of muscle fibers for expression profiling based upon the presence/absence of electron transport dysfunction caused by the somatic accumulation of mitochondrial DNA deletion mutations.
Project description:To gain understanding on the mechanisms that drive immunosenescence in humans, we examined CD4+ T cells obtained from younger (20-39 years-old) and older (70+ years-old) healthy participants of the Baltimore Longitudinal Study on Aging (BLSA). We found that mitochondrial proteins involved in the electron transport chain were overrepresented in cells from older participants, with prevalent dysregulation of oxidative phosphorylation and energy metabolism molecular pathways. Surprisingly, gene transcripts coding for mitochondrial proteins pertaining to oxidative phosphorylation and electron transport chain pathways were underrepresented in older individuals. Paralleling the observed decrease in gene expression, mitochondrial respiration was impaired in CD4+ T cells from older subjects. Though mitochondrial number in both naïve and memory cells visualized with electron microcopy was similar in older versus younger participants, there were a significantly higher number of autophagosomes, many of them containing undegraded mitochondria, in older individuals. The presence of mitochondria inside the accumulated autophagic compartments in CD4+ T cells from older individuals was confirmed by immunofluorescence. These findings suggest that older age is associated with persistence of dysfunctional mitochondria in CD4+ T lymphocytes caused by defective mitochondrial turnover by autophagy, which may trigger chronic inflammation and contribute to the impairment of immune defense in older persons.
Project description:mitochondrial electron transport in Arabidopsis leaves was blocked by antimycin A treatment to trigger mitochondrial production of reactive oxygen species and to study transcriptional changes in response
Project description:We analyzed expression of 81 normal muscle samples from humans of varying ages, and have identified a molecular profile for aging consisting of 250 age-regulated genes. This molecular profile correlates not only with chronological age but also with a measure of physiological age. We compared the transcriptional profile of muscle aging to previous transcriptional profiles of aging in kidney and brain, and found a common signature for aging in these diverse human tissues. The common aging signature consists of six genetic pathways; four pathways increase expression with age (genes in the extracellular matrix, genes involved in cell growth, genes encoding factors involved in complement activation, and genes encoding components of the cytosolic ribosome), while two pathways decrease expression with age (genes involved in chloride transport and genes encoding subunits of the mitochondrial electron transport chain). We also compared transcriptional profiles of aging in human to those of the mouse and fly, and found that the electron transport chain pathway decreases expression with age in all three organisms, suggesting that this may be a public marker for aging across species. Keywords: time course
Project description:Mitochondrial electron transport in Arabidopsis leaves was blocked by antimycin A treatment to trigger mitochondrial production of reactive oxygen species in a knockout line for a mitochondrial peroxidase (PrxII F) and to study transcriptional changes in response
Project description:We analyzed expression of 81 normal muscle samples from humans of varying ages, and have identified a molecular profile for aging consisting of 250 age-regulated genes. This molecular profile correlates not only with chronological age but also with a measure of physiological age. We compared the transcriptional profile of muscle aging to previous transcriptional profiles of aging in kidney and brain, and found a common signature for aging in these diverse human tissues. The common aging signature consists of six genetic pathways; four pathways increase expression with age (genes in the extracellular matrix, genes involved in cell growth, genes encoding factors involved in complement activation, and genes encoding components of the cytosolic ribosome), while two pathways decrease expression with age (genes involved in chloride transport and genes encoding subunits of the mitochondrial electron transport chain). We also compared transcriptional profiles of aging in human to those of the mouse and fly, and found that the electron transport chain pathway decreases expression with age in all three organisms, suggesting that this may be a public marker for aging across species. Experiment Overall Design: Human skeletal muscle samples of various ages (spanning 16-89 years) were surgically removed from patients and gene expression changes with age profiled using Affymetrix HU-133 2.0 arrays. 62 muscles were taken from the rectus abdominis; 19 were taken from various other regions of the anatomy.
Project description:Decreased mitochondrial mass and function in muscle of diabetic patients is associated with low PGC-1alpha, a transcriptional coactivator of the mitochondrial gene program. To investigate whether reduced PGC-1alpha and oxidative capacity in muscle directly contributes to age-related glucose intolerance, we compared the genetic signatures and metabolic profiles of aging mice lacking muscle PGC-1alpha. Microarray analysis revealed that a significant proportion of PGC-1alpha-dependent changes in gene expression overlapped with age-associated effects, and aging muscle and muscle lacking PGC-1alpha shared gene signatures of impaired electron transport chain activity and TGFbeta signalling. Gastrocnemius muscle mRNA from young (10 week old) and old (24 month old) wild-type and knock-out (muscle-specific PGC-1alpha, myogenin-cre) C57Bl/6N/6J/129 mice
Project description:Decreased mitochondrial mass and function in muscle of diabetic patients is associated with low PGC-1alpha, a transcriptional coactivator of the mitochondrial gene program. To investigate whether reduced PGC-1alpha and oxidative capacity in muscle directly contributes to age-related glucose intolerance, we compared the genetic signatures and metabolic profiles of aging mice lacking muscle PGC-1alpha. Microarray analysis revealed that a significant proportion of PGC-1alpha-dependent changes in gene expression overlapped with age-associated effects, and aging muscle and muscle lacking PGC-1alpha shared gene signatures of impaired electron transport chain activity and TGFbeta signalling.