Similar Datasets
Project description:The involvement of microglia and neuroinflammation in amyotrophic lateral sclerosis (ALS) is well recognized, but the precise underlying molecular mechanisms remain elusive. We generated single-nuclei transcriptomic profiles from the spinal cord and motor cortex of sporadic (sALS) and C9orf72 (C9-ALS) ALS patients. We confirmed that C9orf72 is highly expressed in microglia and observed that the hexanucleotide repeat expansion (HRE) results in haploinsufficiency specifically in these cells. Whereas sALS microglia transitioned towards classically defined disease-associated transcriptomic profiles, C9orf72 HRE microglia exhibited a diminished response, with alterations in phagocytic and lysosomal pathways. We confirmed these observations using a human microglia xenograft model, which showed that C9orf72 loss-of-function leads to a reduced baseline activation, with lower expression of antigen-presenting related genes. We also confirmed the alterations in the endolysosomal pathway in C9orf72-HRE and C9orf72-deficient induced pluripotent stem cell (iPSC)-derived microglia. In addition, we observed a diminished response of astrocytes in C9orf72-HRE carriers and provided an extensive map of dysregulated ligand-receptor pairs in microglia and astrocyte indicating an altered cell-cell communication in both C9orf72 and sALS. This complex cellular interplay highlights variations in the cellular substrate of sporadic and inherited forms of ALS, providing valuable insights for patient stratification and for selecting appropriate treatments.
2025-10-20 | GSE302319 | GEO
Project description:The involvement of microglia and neuroinflammation in amyotrophic lateral sclerosis (ALS) is well recognized, but the precise underlying molecular mechanisms remain elusive. We generated single-nuclei transcriptomic profiles from the spinal cord and motor cortex of sporadic (sALS) and C9orf72 (C9-ALS) ALS patients. We confirmed that C9orf72 is highly expressed in microglia and observed that the hexanucleotide repeat expansion (HRE) results in haploinsufficiency specifically in these cells. Whereas sALS microglia transitioned towards classically defined disease-associated transcriptomic profiles, C9orf72 HRE microglia exhibited a diminished response, with alterations in phagocytic and lysosomal pathways. We confirmed these observations using a human microglia xenograft model, which showed that C9orf72 loss-of-function leads to a reduced baseline activation, with lower expression of antigen-presenting related genes. We also confirmed the alterations in the endolysosomal pathway in C9orf72-HRE and C9orf72-deficient induced pluripotent stem cell (iPSC)-derived microglia. In addition, we observed a diminished response of astrocytes in C9orf72-HRE carriers and provided an extensive map of dysregulated ligand-receptor pairs in microglia and astrocyte indicating an altered cell-cell communication in both C9orf72 and sALS. This complex cellular interplay highlights variations in the cellular substrate of sporadic and inherited forms of ALS, providing valuable insights for patient stratification and for selecting appropriate treatments.
2025-10-20 | GSE302295 | GEO
Project description:C9orf72 hexanucleotide repeat expansions impair microglial response in models of ALS
| PRJNA1289862 | ENA
Project description:C9orf72 hexanucleotide repeat expansions impair microglial response in models of ALS [RNA]
| PRJNA1289820 | ENA
Project description:C9orf72 hexanucleotide repeat expansions impair microglial response in models of ALS [scRNA]
| PRJNA1289863 | ENA
Project description:It has been recently reported that a large proportion of patients with familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are associated with a hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72. We have assessed 1757 Italian sporadic ALS cases, 133 from Sardinia, 101 from Sicily, and 1523 from mainland Italy. Sixty (3.7%) of 1624 mainland Italians and Sicilians and 9 (6.8%) of the 133 Sardinian sporadic ALS cases carried the pathogenic repeat expansion. None of the 619 regionally matched control samples (1238 chromosomes) carried the expansion. Twenty-five cases (36.2%) had behavioral FTD in addition to ALS. FTD or unspecified dementia was also detected in 19 pedigrees (27.5%) in first-degree relatives of ALS patients. Cases carrying the C9ORF72 hexanucleotide expansion survived 1 year less than cases who did not carry this mutation. In conclusion, we found that C9ORF72 hexanucleotide repeat expansions represents a sizeable proportion of apparent sporadic ALS in the Italian and Sardinian population, representing by far the most common mutation in Italy and the second most common in Sardinia.
| S-EPMC3372681 | biostudies-literature
Project description: Not available
| S-EPMC3467648 | biostudies-literature
Project description:IMPORTANCE:Hexanucleotide repeat expansions in the chromosome 9 open reading frame 72 (C9orf72) gene underlie a significant fraction of frontotemporal dementia and amyotrophic lateral sclerosis. OBJECTIVE:To investigate the frequency of C9orf72 repeat expansions in clinically diagnosed late-onset Alzheimer disease (AD). DESIGN, SETTING, AND PATIENTS:This case-control study genotyped the C9orf72 repeat expansion in 872 unrelated familial AD cases and 888 control subjects recruited as part of the National Institute on Aging Late-Onset Alzheimer Disease Family Study cohort, a multisite collaboration studying 1000 families with 2 or more individuals clinically diagnosed as having late-onset AD. MAIN OUTCOMES AND MEASURES:We determined the presence or absence of the C9orf72 repeat expansion by repeat-primed polymerase chain reaction, the length of the longest nonexpanded allele, segregation of the genotype with disease, and clinical features of repeat expansion carriers. RESULTS Three families showed large C9orf72 hexanucleotide repeat expansions. Two additional families carried more than 30 repeats. Segregation with disease could be demonstrated in 3 families. One affected expansion carrier had neuropathology compatible with AD. In the National Institute on Aging Late-Onset Alzheimer Disease Family Study series, the C9orf72 repeat expansions constituted the second most common pathogenic mutation, just behind the PSEN1 A79V mutation, highlighting the heterogeneity of clinical presentations associated with repeat expansions. CONCLUSIONS AND RELEVANCE:C9orf72 repeat expansions explain a small proportion of patients with a clinical presentation indistinguishable from AD, and they highlight the necessity of screening frontotemporal dementia genes in clinical AD cases with strong family history.
| S-EPMC3681841 | biostudies-literature
Project description:Due to the GC-rich, repetitive nature of C9orf72 hexanucleotide repeat expansions, PCR based detection methods are challenging. Several limitations of PCR have been reported and overcoming these could help to define the pathogenic range. There is also a need to develop improved repeat-primed PCR assays which allow detection even in the presence of genomic variation around the repeat region. We have optimised PCR conditions for the C9orf72 hexanucleotide repeat expansion, using betaine as a co-solvent and specific cycling conditions, including slow ramping and a high denaturation temperature. We have developed a flanking assay, and repeat-primed PCR assays for both 3' and 5' ends of the repeat expansion, which when used together provide a robust strategy for detecting the presence or absence of expansions greater than ∼100 repeats, even in the presence of genomic variability at the 3' end of the repeat. Using our assays, we have detected repeat expansions in 47/442 Scottish ALS patients. Furthermore, we recommend the combined use of these assays in a clinical diagnostic setting.
| S-EPMC4978699 | biostudies-literature
Project description:The abnormal GGGGCC hexanucleotide repeat expansions (HREs) in C9orf72 cause the fatal neurodegenerative diseases including amyotrophic lateral sclerosis and frontotemporal dementia. The transcribed RNA HREs, short for r(G4C2)n, can form toxic RNA foci which sequestrate RNA binding proteins and impair RNA processing, ultimately leading to neurodegeneration. Here, we determined the crystal structure of r(G4C2)2, which folds into a parallel tetrameric G-quadruplex composed of two four-layer dimeric G-quadruplex via 5'-to-5' stacking in coordination with a K+ ion. Notably, the two C bases locate at 3'- end stack on the outer G-tetrad with the assistance of two additional K+ ions. The high-resolution structure reported here lays a foundation in understanding the mechanism of neurological toxicity of RNA HREs. Furthermore, the atomic details provide a structural basis for the development of potential therapeutic agents against the fatal neurodegenerative diseases ALS/FTD.
| S-EPMC11260476 | biostudies-literature