Project description:We screened nine genetically diverse inbred mouse strains for differences in axonal growth of adult dorsal root ganglion (DRG) neurons on CNS myelin. Naïve DRG neurite outgrowth on myelin was very limited, but preconditioning the neurons by a prior sciatic nerve crush increased axonal growth substantially across all strains, with by far the greatest change in neurons from CAST/Ei mice. Three independent in vivo CNS injury models revealed greater capacity for CNS axonal regeneration in CAST/Ei than C57BL/6 mice. Full-genome expression profiling of naïve and pre-conditioned DRGs across all strains revealed Activin-βA (Inhba) as the transcript whose expression most closely correlated with axonal growth on myelin. In vitro and in vivo gain- and loss-of-function experiments confirmed that Activin promotes axonal growth in the CNS. Substantial regeneration is possible, therefore, in the injured mammalian CNS when Activin signaling is intrinsically high, as in CAST/Ei or when extrinsically modulated in other strains. 9 strains, 4 replicates per strain, 2 conditions (naïve and axotomy) = 72 samples. 2 samples were excluded because technical outliers (AJ_AX5D_1 and AJ_NAIVE_4 excluded from the normalized data but included in the raw data)
Project description:We screened nine genetically diverse inbred mouse strains for differences in axonal growth of adult dorsal root ganglion (DRG) neurons on CNS myelin. Naïve DRG neurite outgrowth on myelin was very limited, but preconditioning the neurons by a prior sciatic nerve crush increased axonal growth substantially across all strains, with by far the greatest change in neurons from CAST/Ei mice. Three independent in vivo CNS injury models revealed greater capacity for CNS axonal regeneration in CAST/Ei than C57BL/6 mice. Full-genome expression profiling of naïve and pre-conditioned DRGs across all strains revealed Activin-βA (Inhba) as the transcript whose expression most closely correlated with axonal growth on myelin. In vitro and in vivo gain- and loss-of-function experiments confirmed that Activin promotes axonal growth in the CNS. Substantial regeneration is possible, therefore, in the injured mammalian CNS when Activin signaling is intrinsically high, as in CAST/Ei or when extrinsically modulated in other strains.
Project description:Nogo-A localized on myelin adaxonal membrane in the adult CNS is well known for its role as neurite outgrowth inhibitor following a lesion. Nogo-A KO mice show enhanced regenerative/compensatory fiber growth following CNS lesion. However, changes undergoing in their intact CNS have not been studied. Moreover, Nogo-A in the intact adult CNS in also expressed in some neuronal subpopulations, e.g. in the hippocampus, olfactory bulbs and dorsal root ganglia. We compared the intact adult CNS (spinal cord) of Nogo-A KO mice in order to identify: potential compensating molecules which could be interesting new inhibitory neurite outgrowth candidates, possible molecules involved in the up to now not yet clarified downstream signalling pathway of Nogo-A, additional new functions for myelin or neuronal Nogo-A in the intact adult CNS. Keywords: gene expression, Nogo-A KO, spinal cord, adult, naive, unlesioned
Project description:The acetylation levels of histones and other proteins change during aging and have been linked to neurodegeneration. Here we show that deletion of the histone acetyltransferase (HAT) co-factor Trrap specifically impairs the function of the transcription factor Sp1, reduces its stability and causes a decrease in histone acetylation at Sp1 target genes. Modulation of Sp1 function by Trrap acts as a hub regulating multiple processes involved in neuron and neural stem cells function and maintenance including microtubule dynamics and the Wnt signaling pathway. Consistently, Trrap conditional mutants exhibit all hallmarks of neurodegeneration including dendrite retraction and axonal swellings, neuron death, astrogliosis, microglia activation, demyelination and decreased adult neurogenesis. Our results uncovered a novel functional network, essential to prevent neurodegeneration, and involving the specific regulation of Sp1 transcription factor and its downstream targets by Trrap-HAT.
Project description:1. Aging is a major risk factor for the development of nervous system functional decline, even in the absence of diseases or trauma. The axon–myelin units and synaptic terminals are some of the neural structures most vulnerable to aging-related deterioration, but the underlying mechanisms are poorly understood. In the peripheral nervous system, macrophages—important representatives of the innate immune system—are prominent drivers of structural and functional decline of myelinated fibers and motor endplates during aging. Similarly, in the aging central nervous system (CNS), microglial cells promote damage of myelinated axons and synapses. Here we examine the role of cytotoxic CD8+ T lymphocytes, a type of adaptive immune cells previously identified as amplifiers of axonal perturbation in various models of genetically mediated CNS diseases but understudied in the aging CNS. We show that accumulation of CD8+ T cells drives axon degeneration in the normal aging mouse CNS and contributes to age-related cognitive and motor decline. We characterize CD8+ T-cell population heterogeneity in the adult and aged mouse brain by single-cell transcriptomics and identify aging-related changes. Mechanistically, we provide evidence that CD8+ T cells drive axon degeneration in a T-cell receptor- and granzyme B-dependent manner. Cytotoxic neural damage is further aggravated by systemic inflammation in aged but not adult mice. We also find increased densities of T cells in white matter autopsy material from older humans. Our results suggest that targeting CD8+ CNS-associated T cells in older adults might mitigate aging-related decline of brain structure and function. 2. Myelin defects lead to neurological dysfunction in various diseases and in normal aging. Chronic neuroinflammation often contributes to axon-myelin damage in these conditions and can be initiated and/or sustained by perturbed myelinating glia. We have previously shown that distinct mutations in the PLP1 gene result in neurodegeneration that is largely driven by adaptive immune cells. Here we characterize CD8+ CNS-associated T cells in these myelin mutants using single-cell transcriptomics and identify population heterogeneity and disease-associated changes. We demonstrate that early sphingosine-1-phosphate receptor modulation attenuates the recruitment of T cells and neural damage, while later targeting of CNS-associated T cell populations is inefficient and has no effect on neurodegeneration. Applying bone marrow chimerism and utilizing random X chromosome inactivation, we provide evidence that axonal damage is driven by cytotoxic, antigen specific CD8+ T cells that target mutant oligodendrocyte myelin. These findings offer insights into neural-immune interactions and are of translational relevance for neurological conditions associated with myelin defects and neuroinflammation.
Project description:Spontaneous neural repair from endogenous neural stem cells (NSCs) occurs in response to central nervous system (CNS) injuries or diseases to only a limited extent from endogenous NSCs niches. Uncovering the mechanisms that control neural repair and can be further manipulated to promote towards oligodendrocyte progenitors cells (OPCs) and myelinating oligodendrocytes is a major objective. Our aim was to identify myelin specific transcriptional regulators amongst large transcriptional changes shortly after differentiation of neural stem cells from the subventricular zone (SVZ) of adult mice SVZ-NSCs from adult mice were differentiated for 12 and 24 h in absence of growth factor (bFGF, EGF) and subjected for gene array as compared with undifferentiated NSCs cultured in presence of growth factors (n=5 samples per condition).
Project description:Nogo-A localized on myelin adaxonal membrane in the adult CNS is well known for its role as neurite outgrowth inhibitor following a lesion. Nogo-A KO mice show enhanced regenerative/compensatory fiber growth following CNS lesion. However, changes undergoing in their intact CNS have not been studied. Moreover, Nogo-A in the intact adult CNS in also expressed in some neuronal subpopulations, e.g. in the hippocampus, olfactory bulbs and dorsal root ganglia. We compared the intact adult CNS (spinal cord) of Nogo-A KO mice in order to identify: potential compensating molecules which could be interesting new inhibitory neurite outgrowth candidates, possible molecules involved in the up to now not yet clarified downstream signalling pathway of Nogo-A, additional new functions for myelin or neuronal Nogo-A in the intact adult CNS. Keywords: gene expression, Nogo-A KO, spinal cord, adult, naive, unlesioned Spinal cords from 3 adult C57Bl/6 wild type and Nogo-A KO mice have been explanted. Total RNA has been extracted and processed for hybridization on Mouse 430 2.0 Affymetrix GeneChips. Following scanning and first analysis with MAS 5.0, further analysis was performed by GeneSpring 7.2 (Silicon Genetics, Redwood City, CA). A present call filter (2 out of 3 present calls in at least one out of the different studied conditions) was applied. Normalization was run per chip as well as per gene to the median of the control replicates. Data were statistical restricted through a 1-way Anova (p=0.05). A final threshold of =1.2 folds of increase or decrease in the expression level of each single transcript was applied. Regulated transcripts have been assigned to functional categories according to GeneOntology as well as literature and database mining (Pubmed and Bioinformatics Harvester EMBL Heidelberg).
Project description:Spontaneous neural repair from endogenous neural stem cells (NSCs) occurs in response to central nervous system (CNS) injuries or diseases to only a limited extent from endogenous NSCs niches. Uncovering the mechanisms that control neural repair and can be further manipulated to promote towards oligodendrocyte progenitors cells (OPCs) and myelinating oligodendrocytes is a major objective. Our aim was to identify myelin specific transcriptional regulators amongst large transcriptional changes shortly after differentiation of neural stem cells from the subventricular zone (SVZ) of adult mice