Single Cell Transcriptomics Reveals Dysregulated Cellular and Molecular Networks in a Fragile X Syndrome model

Donnard, Elisa; Shu, Huan; Garber, Manuel

doi:10.1101/2020.02.12.946780

Cited by 7 publications

(8 citation statements)

References 112 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our small sample size of Fragile X syndrome increases chances that changes in cellular proportion or transcriptional dysregulation may be due to stochastic artifacts. However, replication of past findings including reduced FMR1 expression (Pieretti et al, 1991; Bhattacharyya & Zhao, 2016), increased OPC proportion (Doll et al, 2021), and widespread evidence of metabolic stress (Donnard et al, 2020; Kang et al, 2021), corroborate known molecular neuropathology of the disorder (Licznerski et al, 2020).…”

Section: Discussionsupporting

confidence: 62%

“…However, replication of past findings including reduced FMR1 expression (Pieretti et al, 1991;Bhattacharyya & Zhao, 2016), increased OPC proportion (Doll et al, 2021), and widespread evidence of metabolic stress (Donnard et al, 2020;Kang et al, 2021), corroborate known molecular neuropathology of the disorder (Licznerski et al, 2020). Thus, our findings highlight the need for more comprehensive study of Fragile X in human tissue directly in a variety of different cell types.…”

Section: Cellular Proportionmentioning

confidence: 52%

See 1 more Smart Citation

Glial dysregulation in human brain in Fragile X-related disorders

Dias

Talukdar

Akula

et al. 2022

Preprint

View full text Add to dashboard Cite

While large trinucleotide repeat expansions at the FMR1 locus cause Fragile X Syndrome (FXS), smaller “premutations” are associated with the late-onset condition Fragile X-associated tremor/ataxia syndrome (FXTAS), which shows very different clinical and pathological features, with no clear molecular explanation for these marked differences. One prevailing theory posits that the premutation uniquely causes neurotoxic increases in FMR1 mRNA (i.e., 4-8-fold increases), but evidence to support this hypothesis is largely derived from analysis of peripheral blood. We applied single-nucleus RNA-sequencing to post-mortem frontal cortex and cerebellum from 9 individuals with Fragile X mutations as well as age and sex matched controls (n=6) to assess cell-type specific molecular neuropathology. We found robust reduction of FMR1 mRNA in FXS as expected, with modest but significant upregulation (~1.3 fold) of FMR1 in glial clusters associated with premutation expansions. In premutation cases we identified alterations in glia number in cortex and cerebellum. Differential expression analysis demonstrated altered cortical oligodendrocyte development, while gene ontology analysis revealed alterations in neuroregulatory roles of glia, such as glial modulation of neurotransmission and synaptic structure. We identified significant enrichment of known FMR1 protein target genes in differentially expressed gene lists in FXS as well as the premutation, suggesting FMR1 protein target pathways may represent a shared source of dysfunction in both conditions despite opposite FMR1 mRNA changes. These findings challenge existing dogma regarding FXTAS and implicate glial dysregulation as a critical facet of premutation pathophysiology, representing novel therapeutic targets directly derived from the human condition.

show abstract

Section: Discussionsupporting

confidence: 62%

Section: Cellular Proportionmentioning

confidence: 52%

Glial dysregulation in human brain in Fragile X-related disorders

Dias

Talukdar

Akula

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Our study shows that in the FK mouse brain cortex, steady state mRNA levels are globally disrupted, which drive the dysregulated translational buffering (Fig 1, 5). FMRP targets are particularly downregulated, which happens specifically in neurons (50). By metabolic labeling and RNA-seq in neurons, we show that the loss of FMRP results in reduced stability not only of its direct target substrates, but also of other mRNAs with an optimal codon bias (Fig 2, 3).…”

Section: Discussionmentioning

confidence: 68%

FMRP links optimal codons to mRNA stability in neurons

Shu

Donnard

Liu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Fragile X syndrome (FXS) is caused by inactivation of theFMR1gene and loss of encoded FMRP, an RNA binding protein that represses translation of some of its target transcripts. Here we use ribosome profiling and RNA sequencing to investigate the dysregulation of translation in the mouse brain cortex. We find that most changes in ribosome occupancy on hundreds of mRNAs are largely driven by dysregulation in transcript abundance. Many down-regulated mRNAs, which are mostly responsible for neuronal and synaptic functions, are highly enriched for FMRP binding targets. RNA metabolic labeling demonstrates that, in FMRP-deficient cortical neurons, mRNA down-regulation is caused by elevated degradation and is correlated with codon optimality. Moreover, FMRP preferentially binds mRNAs with optimal codons, suggesting that it stabilizes such transcripts through direct interactions via the translational machinery. Finally, we show that the paradigm of genetic rescue of FXS-like phenotypes in FMRP-deficient mice by deletion of theCpeb1gene is mediated by restoration of steady-state RNA levels and consequent rebalancing of translational homeostasis. Our data establish an essential role of FMRP in codon optimality-dependent mRNA stability as an important factor in FXS.

show abstract

“…To further refine Ttyh1 expression in NSC subpopulations, we used the published single-cell sequencing data ( Dulken et al, 2017 ; Donnard et al, 2020 ) to analyze Ttyh1 expression in various NSC subtypes by unsupervised clustering analysis ( Figures 2D,E ). The results showed that Ttyh1 was mainly expressed in qNSCs ( Figure 2E ).…”

Section: Resultsmentioning

confidence: 99%

Transmembrane Protein Ttyh1 Maintains the Quiescence of Neural Stem Cells Through Ca2+/NFATc3 Signaling

Cao

et al. 2021

Front. Cell Dev. Biol.

View full text Add to dashboard Cite

The quiescence, activation, and subsequent neurogenesis of neural stem cells (NSCs) play essential roles in the physiological homeostasis and pathological repair of the central nervous system. Previous studies indicate that transmembrane protein Ttyh1 is required for the stemness of NSCs, whereas the exact functions in vivo and precise mechanisms are still waiting to be elucidated. By constructing Ttyh1-promoter driven reporter mice, we determined the specific expression of Ttyh1 in quiescent NSCs and niche astrocytes. Further evaluations on Ttyh1 knockout mice revealed that Ttyh1 ablation leads to activated neurogenesis and enhanced spatial learning and memory in adult mice (6–8 weeks). Correspondingly, Ttyh1 deficiency results in accelerated exhaustion of NSC pool and impaired neurogenesis in aged mice (12 months). By RNA-sequencing, bioinformatics and molecular biological analysis, we found that Ttyh1 is involved in the regulation of calcium signaling in NSCs, and transcription factor NFATc3 is a critical effector in quiescence versus cell cycle entry regulated by Ttyh1. Our research uncovered new endogenous mechanisms that regulate quiescence versus activation of NSCs, therefore provide novel targets for the intervention to activate quiescent NSCs to participate in injury repair during pathology and aging.

show abstract

Single Cell Transcriptomics Reveals Dysregulated Cellular and Molecular Networks in a Fragile X Syndrome model

Cited by 7 publications

References 112 publications

Glial dysregulation in human brain in Fragile X-related disorders

Glial dysregulation in human brain in Fragile X-related disorders

FMRP links optimal codons to mRNA stability in neurons

Transmembrane Protein Ttyh1 Maintains the Quiescence of Neural Stem Cells Through Ca2+/NFATc3 Signaling

Contact Info

Product

Resources

About