Loss of Tmem106b leads to cerebellum Purkinje cell death and motor deficits
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE165105 | GEO | 2021/01/20
REPOSITORIES: GEO
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Project description:Loss of Tmem106b leads to cerebellum Purkinje cell death and motor deficits
| PRJNA693266 | ENA
Project description:Genetic variants that define two distinct haplotypes at the TMEM106B locus have been implicated in multiple neurodegenerative diseases and in healthy brain aging. In frontotemporal dementia (FTD), the high expressing TMEM106B risk haplotype was shown to increase susceptibility for FTD with TDP-43 inclusions (FTD-TDP) and to modify disease penetrance in progranulin mutation carriers (FTD-GRN). To further elucidate the biological function of TMEM106B and determine whether lowering TMEM106B may be a viable therapeutic strategy, we performed brain transcriptomic analyses in 8-month-old animals from our recently developed Tmem106b-/- mouse model. We included 10 Tmem106b+/+ (WT), 10 Tmem106b+/- and 10 Tmem106-/- mice. The most differentially expressed genes (153 down-regulated and 60 upregulated) were identified between Tmem106b-/- and WT animals, with an enrichment for genes implicated in myelination-related cellular processes including axon ensheathment and oligodendrocyte differentiation. Co-expression analysis also revealed that the most downregulated group of correlated genes was enriched for myelination-related processes. We further detected a significant loss of Olig2-positive cells in the corpus callosum of Tmem106b-/- mice, which was present already in young animals (21 days) and persisted until old age (23 months), without worsening. qPCR revealed a reduction of differentiated but not undifferentiated oligodendrocytes cellular markers. While no obvious changes in myelin were observed at the ultrastructure levels in unchallenged animals, treatment with cuprizone revealed that Tmem106b-/- mice are more susceptible to cuprizone-induced de-myelination and have a reduced capacity to re-myelinate, a finding which we were able to replicate in a newly generated Tmem106b CRISPR/cas9 knock-out mouse model. Finally, using a TMEM106B HeLa knock-out cell line, we determined that loss of TMEM106B leads to abnormalities in the distribution of lysosomes and PLP1 trafficking but not to differences in MOG trafficking which is lysosome-independent. Together these findings reveal an important function for TMEM106B in myelination with possible consequences for therapeutic strategies aimed at lowering TMEM106B levels.
2020-02-15 | GSE145314 | GEO
Project description:TMEM106B has been recently implicated in multiple neurodegenerative diseases. Here, Rademakers et al. report a late-onset cerebellar Purkinje cell loss and progressive decline in motor function and gait deficits in a conventional Tmem106b-/- mouse model. By using high-power microscopy and bulk RNA sequencing, the authors further identify lysosomal and immune dysfunction as potential underlying mechanisms of the Purkinje cell loss.
| S-EPMC8412084 | biostudies-literature
Project description:Loss of Tmem106b leads to myelination deficits: implications for FTD treatment strategies
| PRJNA606744 | ENA
Project description:The lysosomal protein TMEM106B was identified as a risk modifier of multiple dementias including frontotemporal dementia and Alzheimer's disease. The gene comes in two major haplotypes, one associated with disease risk, and by comparison, the other with protection. Only one coding polymorphism distinguishes the alleles, a threonine-to-serine substitution at residue 185 (186 in mouse). Transcriptional studies suggest synaptic, neuronal, and cognitive preservation in subjects with the protective haplotype, while in vitro studies revealed dramatic effects of TMEM106B deletion on neuronal development. Despite this background, the field has not yet resolved whether coding variant is biologically meaningful, and if so, whether it has any specific effect on neuronal phenotypes. Here we studied how loss of TMEM106B or expression of the lone coding variant affected transcriptional signatures in the mature brain and neuronal structure during development in primary neurons. We show that homozygous expression of the TMEM106B T186S variant in knock-in mice increased cortical expression of genes associated with excitatory synaptic function and axon outgrowth, and promoted neurite branching, dendritic spine density, and synaptic density in primary hippocampal neurons. In contrast, constitutive TMEM106B deletion affected transcriptional signatures of myelination without altering neuronal development in vitro. Our findings show that the T186S variant is functionally relevant and may contribute to disease resilience during neurodevelopment.
2023-11-02 | GSE240156 | GEO
Project description:The signalling protein PKCγ is a major regulator of Purkinje cell development and synaptic function. We have shown previously that increased PKCγ activity impairs dendritic development of cerebellar Purkinje cells. Mutations in the protein kinase Cγ gene (PRKCG) cause spinocerebellar ataxia type 14 (SCA14). In a transgenic mouse model of SCA14 expressing the human S361G mutation, Purkinje cell dendritic development is impaired in cerebellar slice cultures similar to pharmacological activation of PKC. The mechanisms of PKCγ-driven inhibition of dendritic growth are still unclear. Using immunoprecipitation-coupled mass spectrometry analysis we have identified Collapsin Response Mediator Protein 2 (CRMP2) as a protein interacting with constitutive active PKCγ(S361G) and confirmed the interaction with the Duolink™ proximity ligation assay. We show that in cerebellar slice cultures from PKCγ(S361G)- mice, phosphorylation of CRMP2 at the known PKC target site Thr555 is increased in Purkinje cells confirming phosphorylation of CRMP2 by PKCγ. miRNA-mediated CRMP2 knockdown decreased Purkinje cell dendritic outgrowth in dissociated cerebellar cultures as did the transfection of CRMP2 mutants with a modified Thr555 site. In contrast, dendritic development was normal after wildtype CRMP2 overexpression. In a novel knock-in mouse expressing only the phospho-defective T555A-mutant CRMP2, Purkinje cell dendritic development was reduced in dissociated cultures. This reduction could be rescued by transfecting wildtype CRMP2 but only partially by the phospho-mimetic T555D-mutant. Our findings establish CRMP2 as an important target of PKCγ phosphorylation in Purkinje cells mediating its control of dendritic development. Dynamic regulation of CRMP2 phosphorylation via PKCγ is required for its correct function.
2022-02-24 | PXD020124 | Pride
Project description:Specific medications to combat cerebellar ataxias, a group of debilitating movement disorders characterized by difficulty with walking, balance and coordination. Notably, cerebellar microglial activation appears to be a common feature in different types of ataxic patients and rodent models. However, the causal link between the activation of microglia in the cerebellum and ataxias remains inconclusive. In the present study, using a classic mouse model of cerebellar ataxia induced by 3-acetylpyridine (3-AP), we find a early-onset and long-lasting microglial activation accompanied by neuronal loss and dysfunction in the cerebellum. Transcriptome and behavior analyses indicate that microglial depletion in 3-AP ataxic mice decreases neuroinflammatory response in the cerebellum and rescues the ataxic motor symptoms including motor incoordination, gait abnormality, and locomotor dysfunction. Moreover, specific chemogenetic activation of cerebellar microglia in the vermis by M3D(Gq), a designer receptor exclusively activated by designer drugs (DREADDs), directly induces an expression of pro-inflammatory cytokines and aggravates ataxic motor deficits of 3-AP mice. On the contrary, inhibition of cerebellar microglial activation by M4D(Gi) or minocycline reduces the production of pro-inflammatory cytokines including TNF-α and alleviates motor deficits. Furthermore, blockage of TNF-α signaling attenuates the microglial-triggered hyperactivity of Purkinje cells (PCs). These results suggest that cerebellar microglial activation aggravates neuroinflammatory response, and subsequently induces dysfunction of PCs, which in turn triggers ataxic motor deficits. Our findings thus reveal a causal relationship between pro-inflammatory activation of cerebellar microglia and the ataxic motor symptoms, which may offer novel evidence for therapeutic intervention for cerebellar ataxias by targeting microglia and microglia-derived inflammatory mediators.
2023-07-01 | GSE221991 | GEO
Project description:We analyzed Purkinje cell transcriptome dynamics in the developing mouse cerebellum during the first three postnatal weeks, a key developmental period equivalent to the third trimester in human cerebellar development. Our study represents the first detailed analysis of developmental Purkinje cell transcriptomes and provides a valuable dataset for gene network analyses and biological questions on genes implicated in cerebellar and Purkinje cell development.
2019-01-31 | GSE86824 | GEO
Project description:Single-cell profiling of stem cell-derived cerebellar organoids revealed transcriptionally-discrete populations encompassing the major cerebellar neuronal cell types including granule cells, roof plate, choroid plexus, Bergmann glia, Purkinje cells and glutamatergic deep cerebellar nuclei. Cellular identity and maturity were confirmed through comparison to an atlas of developing murine cerebellar cell types.
2020-09-30 | GSE150153 | GEO
Project description:Polygenic risk factors influence onset and progression of neurodegenerative diseases, but are difficult to be functionally explored in isolation. Single nucleotide polymorphisms (SNPs) in TMEM106B increase the risk for frontotemporal lobar degeneration (FTLD) of GRN mutation carriers. Currently, it is not clear if progranulin (PGRN) and TMEM106B are synergistically linked and if a gain or a loss-of-function of TMEM106B is responsible for the increased disease risk of patients with PGRN haploinsufficiency. We therefore compared behavioral abnormalities, gene expression patterns, lysosomal activity and TDP-43 pathology in single and double knockout animals. Grn–/–/Tmem106b–/– mice showed a strongly reduced life span and massive motor deficits. Gene expression analysis revealed an upregulation of molecular signatures characteristic for disease associated microglia and autophagy. Dysregulation of maturation of lysosomal proteins as well as a pronounced accumulation of ubiquitinated proteins and wide spread p62 deposition suggest that proteostasis is impaired. Moreover, while single Grn–/– knockouts only occasionally showed TDP-43 pathology, the double knockout mice exhibit robust deposition of phosphorylated TDP-43. Thus, a loss-of-function of TMEM106B may enhance the risk for GRN-associated FTD by reduced protein turnover in the lysosomal/autophagic system.
2020-07-25 | GSE155066 | GEO