The TMEM106B T186S coding variant increases neurite arborization and synaptic density in primary hippocampal neurons
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PROVIDER: PRJNA1002383 | ENA |
REPOSITORIES: ENA
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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 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 resilience. Only one coding polymorphism distinguishes the two alleles, a threonine-to-serine substitution at residue 185 (186 in mouse), that is inherited in disequilibrium with multiple non-coding variants. Transcriptional studies suggest synaptic, neuronal, and cognitive preservation in human subjects with the protective haplotype, while murine in vitro studies reveal dramatic effects of TMEM106B deletion on neuronal development. Despite this foundation, 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 in isolation affected transcriptional signatures in the mature brain and neuronal structure during development in primary neurons. 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.
| S-EPMC10603297 | biostudies-literature
Project description:Reelin is a large, secreted glycoprotein that is best known as an essential molecule directing neocortical neuronal migration, but reelin serves an important functional role in regulating neurite outgrowth and arborization as well. Canonically, reelin signals through the lipoprotein receptors apolipoprotein E receptor 2 (ApoER2) and very low-density lipoprotein receptor (VLDLR). Reelin can signal through non-canonical receptors and unidentified co-receptors as well, but the downstream effects of these non-canonical pathways are not well understood. Using an unbiased Tandem Mass Tag LC-MS/MS (TMT) proteomics screen and gene set enrichment analysis (GSEA), we identified overlapping and distinct intra-cellular pathways enriched downstream of canonical and non-canonical reelin signaling in primary murine neurons during periods of robust neurite arborization. We observed canonical signaling led to substantial changes in actin cytoskeletal dynamics and cell morphogenesis while non-canonical signaling preferentially regulated protein translation, suggesting reelin fine tunes neuronal structure and function through distinct signaling pathways. We also identified a novel node downstream of canonical reelin signaling, glycolytic enzyme and actin binding protein aldolase A (aldo A). Biochemical analysis revealed aldo A undergoes de novo translation and is dissociated from the actin cytoskeleton after acute reelin stimulation. Additionally, shRNA knockdown of aldo A in primary murine cultures and in vivo through in utero electroporation (IUE), reveal aldo A is necessary for reelin mediated neurite growth and the proper arborization and positioning of excitatory layer II/III neurons independent of glycolytic function. These results shed new light on the molecular mechanisms and signaling pathways regulating reelin dependent neuronal arborization.
2025-05-06 | PXD046667 | Pride
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 is an endolysosomal transmembrane protein associated with many brain disorders, such as frontotemporal lobar degeneration, Alzheimer’s disease, and hypomyelinating leukodystrophy. In addition, recent cryo-EM studies have identified amyloid fibrils of carboxyl-terminal TMEM106B in the brains of those with neurodegeneration. However, so far little is known about precise functions of TMEM106B in the endolysosome and how the protein is involved in a great variety of human conditions at molecular levels. In this project, we sought to identify interaction partners of TMEM106B in the mouse brain by using immunoprecitation and liquid chromatography tandem mass spectrometry protein identification procedure.
2024-08-06 | PXD043192 | Pride
Project description:The loss of Tmem106b results in an age-dependent loss of cerebellar Purkinje cells accompanied with motor function deficits. Tmem106b deficiency also results in lysosomal enlargement in both Purkinje cells and microglia, and increased neuroinflammation including complement system activation. These data suggest that, in addition to myelination, Tmem106b also plays important role in maintaining the health and survival of cerebellar Purkinje cells during aging.
2021-01-20 | GSE165105 | GEO
Project description:Background: The risk for dementia increases exponentially from the seventh decade of life. Identifying and understanding the biochemical changes that sensitize the ageing brain to neurodegeneration will provide new opportunities for dementia prevention and treatment. This study aimed to determine how ageing and major genetic risk factors for dementia affect the hippocampal proteome and lipidome of neurologically-normal humans over the age of 65. The hippocampus was chosen as it is highly susceptible to atrophy with ageing and in several neurodegenerative diseases. Methods: Mass spectrometry-based proteomic and lipidomic analysis of CA1 hippocampus samples from 74 neurologically normal human donors, aged 66 – 104, was used in combination with multiple regression models and gene set enrichment analysis to identify age-dependent changes in the proteome and lipidome. ANOVA was used to test the effect of major dementia risk alleles in the TMEM106B and APOE genes on the hippocampal proteome and lipidome, adjusting for age, gender, and post-mortem interval. Fibrillar C-terminal TMEM106B fragments were isolated using sarkosyl fractionation and quantified by immunoblotting. Results: Forty proteins were associated with age at false discovery rate-corrected P<0.05, including proteins that regulate cell adhesion, the cytoskeleton, amino acid and lipid metabolism, and ribosomal subunits. TMEM106B, a regulator of lysosomal and oligodendrocyte function, was regulated with greatest effect size. The increase in TMEM106B levels with ageing was specific to carriers of the rs1990622-A allele in the TMEM106B gene that increases risk for frontotemporal dementia, Alzheimer’s disease, Parkinson’s disease, and hippocampal sclerosis with ageing. Rs1990622-A was also associated with higher TMEM106B fibril content. Hippocampal lipids were not significantly affected by APOE genotype, however levels of myelin-enriched sulfatides and hexosylceramides were significantly lower, and polyunsaturated phospholipids were higher, in rs1990622-A carriers after controlling for APOE genotype. Conclusions: Our study demonstrates that TMEM106B protein abundance is increased with brain ageing in humans, establishes that dementia risk allele rs1990622-A predisposes to TMEM106B fibril formation in the hippocampus, and provides the first evidence that rs1990622-A affects brain lipid homeostasis, particularly myelin lipids. Our data suggests that TMEM106B is one of a growing list of major dementia risk genes that affect glial lipid metabolism.
2023-09-21 | PXD043880 | Pride
Project description:TMEM106B is a risk modifier for a growing list of age-associated dementias including Alzheimer's and frontotemporal dementia, yet its function remains elusive. Two key questions that emerge from past work are whether the conservative T185S coding variant found in the minor haplotype contributes to protection, and whether the presence of TMEM106B is helpful or harmful in the context of disease. Here we address both issues while extending the testbed for study of TMEM106B from models of TDP to tauopathy. We show that TMEM106B deletion accelerates cognitive decline, hindlimb paralysis, neuropathology, and neurodegeneration. TMEM106B deletion also increases transcriptional overlap with human AD, making it a better model of disease than tau alone. In contrast, the coding variant protects against tau-associated cognitive decline, neurodegeneration, and paralysis without affecting tau pathology. Our findings show that the coding variant contributes to neuroprotection and suggest that TMEM106B is a critical safeguard against tau aggregation.
2025-08-05 | GSE223376 | GEO
Project description:Class I and IV Drosophila dendritic arborization sensory neurons were isolated via magnetic bead sorting and total RNA isolated from the samples was used for gene expression profiling. Elucidating the molecular mechanisms controlling dendrite development is key to understanding the pivotal role these structures play in influencing synaptic integration and neural function. Despite significant advances in this field, genetic pleiotropy remains a significant impediment to investigating such complex developmental processes. To circumvent this problem, we have applied class specific neuron transcriptional expression profiling coupled to an in vivo RNAi functional validation screen in order to dissect the molecular bases of Drosophila class I and class IV dendritic arborization (da) neuron dendritogenesis.
2013-07-21 | GSE46154 | GEO
Project description:Heterozygous mutations in the granulin (GRN) gene result in haploinsufficiency of the progranulin (PGRN) protein, a leading cause of frontotemporal lobar degeneration with TDP-43 aggregates (FTLD-TDP). Polymorphisms in the TMEM106B gene have been associated with disease risk in GRN mutation carriers and protective TMEM106B variants are associated with reduced levels of TMEM106B, suggesting that lowering TMEM106B might be therapeutic in the context of FTLD. Here we tested the impact of full deletion and partial reduction of TMEM106B in mouse and iPSC-derived human cell models of GRN deficiency. In vitro, TMEM106B deletion did not reverse transcriptomic and proteomic profiles in GRN-deficient microglia, with the exception of a small set of immune-related proteins in the NF-κB pathway. In vivo, neither homozygous nor heterozygous Tmem106b deletion normalized disease-associated gene expression in sorted microglia, lipid abnormalities, or histopathology in Grn knock-out mice. Furthermore, Tmem106b reduction with antisense oligonucleotide (ASO) treatment was poorly tolerated in Grn knock-out mice. These data provide novel insight into TMEM106B and GRN function in microglia cells but do not support lowering TMEM106B levels as a viable therapeutic strategy for treating FTLD-GRN.
2023-11-15 | GSE237106 | GEO