Project description:Aging reduces locomotor capacity. Although a decrease in the activity of the nigrostriatal dopamine (DA) system is one of key mechanisms linked to the drop-in locomotor activity in aging, the specific molecule responsible for controlling this decline remains elusive. Here we report that sirtuin 3 (SIRT3), a mitochondrial deacetylase associated with an anti-aging effect, is downregulated in nigral DA neurons of 20-month-old mice, showing the decline in locomotor activity, and that the declined locomotor activity by aging was deteriorated with more serious alteration in the levels of mitochondria-related proteins in mice with genetic deletion of SIRT3 compared to age-matched control mice. Moreover, SIRT3 upregulation through the administration of adeno-associated virus serotype 1 (AAV1) encoding the SIRT3 gene in the substantia nigra (SN) mitigated the age-dependent loss of locomotor activity by the preservation of the nigrostriatal DA system from aging in vivo. Therefore, we conclude that SIRT3 preservation in the nigrostriatal DA system has resistance to age-related locomotor decline, suggesting that SIRT3 upregulation in nigral DA neurons can be useful to preserve locomotor capacity in aging.
Project description:Increased levels of the protein alpha-synuclein (α-syn) are associated with the development of neurodegenerative diseases like Parkinson's disease (PD). In physiological conditions, α-syn modulates synaptic plasticity, neurogenesis and neuronal survival. Here, we used a PD patient specific midbrain organoid model derived from induced pluripotent stem cells harboring a triplication in the SNCA gene to study PD-associated phenotypes. The model recapitulates the two main hallmarks of PD, which are α-syn aggregation and loss of dopaminergic neurons. Additionally, impairments in astrocyte differentiation were detected. Transcriptomics data indicate that synaptic function is impaired in PD specific midbrain organoids. This is further confirmed by alterations in synapse number and electrophysiological activity. We found that synaptic decline precedes neurodegeneration. Finally, this study substantiates that patient specific midbrain organoids allow a personalized phenotyping, which make them an interesting tool for precision medicine and drug discovery. However, its pathogenic accumulation and aggregation results in toxicity and neurodegeneration.
Project description:In this study, we showed that reduced nuclear lamin-B marks the onset of physiological decline in young adult Drosophila and its ectopic expression in dopaminergic neurons is sufficient to improve their locomotor activity during aging. Furthermore, the decline in lamin-B protein appeared to be unrelated to its mRNA level. Instead, we found drastic changes to its protein solubility during aging. Given the importance of nuclear lamin-B in genome organization and the advancement of single-cell epigenome profiling technology, our findings provide the community the basis to further study how altered level of lamin-B protein may elicit changes in gene expression that can contribute to the onset of physiological decline in animals.
Project description:How do neurons match generation of adenosine triphosphate (ATP) by mitochondria to the bioenergetic demands of regenerative activity? Although the subject of speculation, this coupling is still poorly understood, particularly in neurons that are tonically active. To help fill this gap, pacemaking substantia nigra dopaminergic neurons were studied using a combination of optical, electrophysiological and molecular approaches. In these neurons, spike-activated calcium (Ca2+) entry through Cav1 channels triggered Ca2+ release from the endoplasmic reticulum, which stimulated mitochondrial OXPHOS through two complementary Ca2+-dependent mechanisms: one mediated by the mitochondrial uniporter and another by the malate-aspartate shuttle. Disrupting either mechanism impaired the ability of dopaminergic neurons to sustain spike activity. While this feedforward control helps dopaminergic neurons meet the bioenergetic demands associated with sustained spiking, it also is responsible for their elevated oxidant stress and possibly to their decline with aging and disease.
Project description:Neuroinflammation plays a key role in modulating dopaminergic neuronal (DAN) cell loss in Parkinson’s disease (PD). However, it remains unresolved how to effectively normalize this immune response given the complex interplay between the innate and adaptive immune responses occurring within a scarcely accessible organ like the brain. In this study, we uncovered a consistent correlation between neuroinflammation, brain parenchymal lymphocytes and DAN cell loss among several commonly used mouse models of PD generated by a variety of pathological triggers. We validated a viral therapeutic approach for the microglia-specific expression of Interleukin 10 (IL-10) to selectively mitigate the excessive inflammatory response. We found that this approach induced a local nigral IL-10 release that sustained a robust neuroprotection against α-Synuclein (αSYN)-induced neurodegeneration. Single-cell transcriptomics revealed the emergence of a molecularly alternative microglial cell state specifically induced by IL-10 enriched in markers of cell activation with enhanced expression of prophagocytic pathways. Indeed, Il-10 strongly promoted phagocytotic and clearance activities that effectively reduced the αSYN aggregate burden in the nigral area. Furthermore, IL-10 stimulated the differentiation of CD4+ T lymphocytes into active T regulatory cells. Finally, CD8+ T cells exhibited enhanced inhibitory characteristics in the presence of IL-10. Thus, IL-10 local transduction elicited a strong immunomodulation in the nigral tissue with enhanced suppression of lymphocyte toxicity, which rescued DAN cell loss. These results offer insights into the therapeutic benefits induced by IL-10, showcasing a promising gene delivery approach that minimizes undesired side effects and has a strong translational relevance.
Project description:Per- and polyfluoroalkyl substances (PFAS) are persistent pollutants known for their bio-accumulative properties and prevalence in water supplies and household products. Although legacy PFAS, such as perfluorooctanoic acid, are phased out in the U.S. due to public health concerns, a PFAS variant hexafluoropropylene oxide-dimer acid (HFPO-DA) is an emerging replacement. HFPO-DA is a potential neurotoxicant that has been shown to cause dopaminergic neurodegeneration. We investigated the bioaccumulative potential of HFPO-DA and its effects on lifespan, locomotor activity, and brain gene expression in female and male Drosophila melanogaster (fruit flies). Flies were collected less than 4 hours post-eclosion and exposed to 0, 10, 10^2, 10^3, or 10^4 mg/kg/day HFPO-DA. To measure the effect of HFPO-DA on lifespan, surviving flies from each exposure were recorded every 24 hours. Flies were subjected to a negative geotaxis assay at 3, 7, and 14 days of exposure to measure the effects of acute, sub-chronic, and chronic exposures on locomotor ability. To capture HFPO-DA-induced sexually dimorphic gene expression responses in the brain, we sequenced brain-specific mRNA from flies exposed for 3, 7, or 14 days. The Bioconcentration Factor was 0.031 for females, and 0.026 for males. Dose and median lifespan were negatively correlated in both female (R^2 adj = 0.77, p<0.0001) and male flies (R^2 adj = 0.77, p<0.0001). Log-rank Mantel-Cox tests and one-way ANOVAs revealed that median lifespan was reduced in females starting at 10 mg/kg/day and in males starting at 10^2 mg/kg/day (p< 0.01). Acute exposure at 10 mg/kg/day significantly decreased locomotor ability in females (p<0.0001) while acute exposures at 1 mg/kg/day decreased locomotor activity in males (p <0.0001). Among 7500 genes analyzed, pairwise gene expression comparison between controls and treatments identified 2496 differentially expressed genes. While HFPO-DA does not readily bioaccumulate in fruit fly bodies, high-dose exposures have sex-specific effects on lifespan, locomotor ability, and brain gene expression. LOAEL for median lifespan is 10 mg/kg/day in females, and 10^2 mg/kg/day in males. Both locomotor ability and brain gene expression exhibited non-conventional dose-response as seen in other endocrine disrupting chemical exposures.
Project description:Lee and colleagues demonstrate that sustained activation of AMPK enhances differentiation of iPSC-derived cardiomyocytes. Sustained AMPK activation decreased histone acetylation at known target sites for nuclear-localized sirtuins, suggesting that AMPK activation enhances sirtuin activity. AMPK-induced sirtuin-mediated deacetylation of histone proteins may regulate chromatin accessibility and enhance cardiomyocyte differentiation.
Project description:Spinal cord injury (SCI) is one of the most disabling health problems facing adults today. Locomotor training has been shown to induce substantial recovery in muscle size and muscle function in both transected and contusion injury animal models of SCI. The overall objective of this study is to implement genome wide expression profiling of skeletal muscle to define the molecular pathways associated with muscle remodeling after SCI and during locomotor training (TM). We profiled rat soleus of total 36 samples including controls; 3, 8 and 14 days after SCI; 8 and 14 days after SCI with locomotor treadmill training (TM).
Project description:Traumatic spinal cord injury (SCI) often leads to loss of locomotor function. Neuroplasticity of spinal circuitry underlies some functional recovery and therefore represents a therapeutic target to improve locomotor function following SCI. However, the cellular and molecular mechanisms mediating neuroplasticity below the lesion level are not fully understood. The present study performed a gene expression profiling in the rat lumbar spinal cord at 1 and 3 weeks after contusive SCI at T9 compared to control rat that received sham injury (laminectomy). The below-level gene expression profiles were compared with those of animals that were subjected to treadmill locomotor training. Rat lumbar spinal cords were taken for the microarray analysis at 1 and 3 weeks after contusive spinal cord injury at the T9 level. Another group of rats received treadmill locomotor training for 3 weeks, and theirs spinal cords were harvested for the microarray. The changes in gene expression after spinal cord injury were analyzed at the two time points. The influence of treadmill locomotor training was evaluated by comparing gene expression profiles between animals with or without treadmill training.