Project description:As human society ages globally, age-related disorders are becoming increasingly common. Due to decreasing physiological reserves and increasing organ system dysfunction associated with age, frailty affects many elderly people, compromising their ability to cope with acute stressors. Frail elderly people commonly manifest complex clinical symptoms, including cognitive dysfunction, hypomobility, and impaired daily activity, the metabolic basis of which has been little understood. We applied untargeted, comprehensive, LC-MS metabolomic analysis to human blood from 19 frail and non-frail elderly patients, who were clinically evaluated using the Edmonton Frail Scale, the MoCA-J for cognition, and the TUG for mobility. Among 131 metabolites assayed, we identified 22 markers for frailty, cognition, and hypomobility, most of which were abundant in blood. Frailty markers included 5 of 6 markers specifically related to cognition and 6 of 12 associated with hypomobility. These overlapping sets of markers include metabolites related to antioxidation, muscle or nitrogen metabolism, and amino acids, most of which decrease in frail elderly people. Five frailty-related metabolites that decreased (1,5-anhydroglucitol, acetyl-carnosine, ophthalmic acid, leucine, and isoleucine) have been previously reported as markers of aging, providing a metabolic link between human aging and frailty. Our findings clearly indicate that metabolite profiles efficiently distinguish frailty from non-frailty. Importantly, the antioxidant, ergothioneine, which decreases in frailty, is neuroprotective. Oxidative stress resulting from diminished antioxidant levels, could be a key vulnerability for pathogenesis of frailty, exacerbating illnesses related to human aging.
Project description:Histone deacetylase (HDAC) 4 is a transcriptional repressor that contains a glutamine rich domain. We hypothesised that it may be involved in the molecular pathogenesis of Huntington's disease (HD), a protein folding neurodegenerative disorder caused by an aggregation-prone polyglutamine expansion and transcriptional dysregulation. We found that HDAC4 interacts with huntingtin in a polyglutamine-length dependent manner and co-localises with cytoplasmic inclusions. We show that HDAC4 reduction delayed cytoplasmic aggregate formation, restored Bdnf transcript levels and rescued neuronal and cortico-striatal synaptic function in HD mouse models. This was accompanied by an improvement in motor co-ordination, neurological phenotypes and increased lifespan. Surprisingly, HDAC4 reduction had no effect on global transcriptional dysfunction and did not modulate nuclear huntingtin aggregation. Our results define a crucial role for cytoplasmic aggregation in the molecular pathology of HD. HDAC4 reduction presents a novel strategy for targeting huntingtin aggregation which may be amenable to small molecule therapeutics. mRNA expression analysis was performed by microarray in 9 weeks old WT (n=9), R6/2 (n=9), HDAC4het (n=9) and Double R6/2::HDAC4het (n=10) mice. Microarray quality control was performed using the software package provided on RACE (http://race.unil.ch).
Project description:Histone deacetylase (HDAC) 4 is a transcriptional repressor that contains a glutamine rich domain. We hypothesised that it may be involved in the molecular pathogenesis of Huntington's disease (HD), a protein folding neurodegenerative disorder caused by an aggregation-prone polyglutamine expansion and transcriptional dysregulation. We found that HDAC4 interacts with huntingtin in a polyglutamine-length dependent manner and co-localises with cytoplasmic inclusions. We show that HDAC4 reduction delayed cytoplasmic aggregate formation, restored Bdnf transcript levels and rescued neuronal and cortico-striatal synaptic function in HD mouse models. This was accompanied by an improvement in motor co-ordination, neurological phenotypes and increased lifespan. Surprisingly, HDAC4 reduction had no effect on global transcriptional dysfunction and did not modulate nuclear huntingtin aggregation. Our results define a crucial role for cytoplasmic aggregation in the molecular pathology of HD. HDAC4 reduction presents a novel strategy for targeting huntingtin aggregation which may be amenable to small molecule therapeutics. mRNA expression analysis was performed by microarray in 15 weeks old WT (n=8), R6/2 (n=9), HDAC4het (n=8) and Double R6/2::HDAC4het (n=9) mice. Microarray quality control was performed using the software package provided on RACE (http://race.unil.ch).
Project description:The mitochondrial ATP synthase produces ATP by oxidative phosphorylation and integrates different signals to regulate cellular functions and fate. The ATPase inhibitory factor 1 (IF1) is a structurally-disordered protein that inhibits the ATP synthase, contributing to metabolic reprogramming and signalling through mitochondrial reactive oxygen species (mtROS). mtROS regulate kinases and transcription factors in mitohormetic responses that favour adaptation to toxic insults2. IF1 is tissue-specifically expressed and in human and mouse brain is in molar excess over the ATP synthase. Herein, we have used genetic approaches to ablate or overexpress IF1 in neurons to investigate its role in brain functions. IF1 inhibits a fraction of the ATP synthase under physiological conditions and regulates respiration, mtROS production and mitochondrial structure. Transcriptomic, proteomic and metabolomic analyses indicate that IF1 regulates synaptic transmission and cognition. Ablation of IF1 impairs short-term memory whereas IF1 overexpression increases basal synaptic transmission and learning by mtROS-dependent activation of the extracellular signal-regulated kinases 1/2 (ERK 1/2). Overall, we show that IF1 dose plays a fundamental role in the regulation of neuronal function by controlling the fraction of inhibited ATP synthase that acts as source of mitohormetic mtROS, further emphasizing the ATP synthase/IF1 as promising targets to treat cognitive disorders.
Project description:Experience powerfully influences neuronal function and cognitive performance, but the cellular and molecular events underlying the experience-dependent enhancement of mental ability have remained elusive. In particular, the mechanisms that couple the external environment to the genomic changes underpinning this improvement are unknown. To address this we have used male mice harbouring an inactivating mutation of mitogen- and stress-activated protein kinase 1 (MSK1), a BDNF-activated enzyme downstream of the MAPK pathway. We show that MSK1 is required for the full extent of experience-induced improvement of spatial memory, for the expansion of the dynamic range of synapses, exemplified by the enhancement of hippocampal LTP and LTD, and for the regulation of the majority of genes influenced by enrichment. In addition, and unexpectedly, we show that experience is associated with an MSK1-dependent downregulation of key MAPK and plasticity-related genes, notably of EGR1/Zif268 and Arc/Arg3.1, suggesting the establishment of a novel genomic landscape adapted to experience. By coupling experience to homeostatic changes in gene expression MSK1, represents a prime mechanism through which the external environment has an enduring influence on gene expression, synaptic function and cognition.
Project description:Histone deacetylase (HDAC) 4 is a transcriptional repressor that contains a glutamine rich domain. We hypothesised that it may be involved in the molecular pathogenesis of Huntington’s disease (HD), a protein folding neurodegenerative disorder caused by an aggregation-prone polyglutamine expansion and transcriptional dysregulation. We found that HDAC4 interacts with huntingtin in a polyglutamine-length dependent manner and co-localises with cytoplasmic inclusions. We show that HDAC4 reduction delayed cytoplasmic aggregate formation, restored Bdnf transcript levels and rescued neuronal and cortico-striatal synaptic function in HD mouse models. This was accompanied by an improvement in motor co-ordination, neurological phenotypes and increased lifespan. Surprisingly, HDAC4 reduction had no effect on global transcriptional dysfunction and did not modulate nuclear huntingtin aggregation. Our results define a crucial role for cytoplasmic aggregation in the molecular pathology of HD. HDAC4 reduction presents a novel strategy for targeting huntingtin aggregation which may be amenable to small molecule therapeutics.