Astrocytes in fragile X syndrome

Probably not a substantial claim: may not pass S3 (load-bearing).

Astrocytes are implicated in various brain pathologies, including neurodevelopmental conditions such as FXS.

“Astrocytes are implicated in various brain pathologies (Lee et al., 2022), including neurodevelopmental conditions such as fragile X syndrome (FXS, Fernández-Blanco and Dierssen, 2020).”

• cites Lee et al., 2022 sourceSupported
• cites Fernández-Blanco and Dierssen, 2020 sourceSupported

May combine two claims.

Immature human FXS astrocytes secrete uPA more than healthy control astrocytes, and increased uPA augments TrkB phosphorylation within the docking site for PLCγ1 in cocultured rat primary neurons.

“These immature human FXS astrocytes also secrete uPA more than healthy control astrocytes, and the increased uPA augments tyrosine receptor kinase B (TrkB) phosphorylation within the docking site for phospholipase-Cγ1 (PLCγ1) in cocultured rat primary neurons (Peteri et al., 2021).”

• cites Peteri et al., 2021 sourcePartly supported

  Section 3.4 reports 5.5-fold higher uPA in medium from human FXS astrocytes than controls. Section 3.6 reports increased phosphorylation of the PLCγ1-binding TrkB site in rat primary cortical neurons exposed to that medium, with the increase prevented by a uPA antibody. The neurons were treated with astrocyte-conditioned medium, not cocultured with the astrocytes as the claim states. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Increased glutamatergic signaling and altered excitatory/inhibitory balance is recognized as a hallmark of FXS.

“Increased glutamatergic signaling and altered excitatory/inhibitory balance is recognized as a hallmark of FXS (Liu et al., 2022).”

• cites Liu et al., 2022 sourcePartly supported

  The Introduction’s “Hyperexcitable Neurons and Networks in Fragile X Syndrome” section describes altered excitatory/inhibitory balance as a contributor to FXS hyperexcitability. The “Altered Excitatory Synaptic Function and Plasticity in FXS” section reports enhanced mGluR-mediated effects in FMR1 knockout mice, but does not establish a general increase in glutamatergic signaling across FXS; it notes that some excitatory-synapse changes could decrease excitatory drive. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Hallmarks of neural circuit function in FXS include hyperexcitability and plasticity defects.

“Hallmarks of neural circuit function in FXS include hyperexcitability and plasticity defects (Martin and Huntsman, 2012).”

• cites Martin and Huntsman, 2012 sourceSupported

May combine two claims.

Blocking antibody to S100B induces disordered firing in co-cultures of control neurons and control astrocytes, demonstrating that astrocyte secreted factors can influence firing patterns of glutamatergic neurons.

“Furthermore, blocking antibody to S100B induced disordered firing in co-cultures of control neurons and control astrocytes (Das Sharma et al., 2023), demonstrating that astrocyte secreted factors can influence the firing patterns of glutamatergic neurons (Das Sharma et al., 2020).”

• cites Das Sharma et al., 2023 sourceSupported
• cites Das Sharma et al., 2020 sourceCould not verify

  The 2020 citation is attached to the conclusion about astrocyte-secreted factors, not the S100B antibody experiment cited to 2023. The Results section reports firing differences in neurons co-cultured with wild-type mouse astrocytes and describes those differences as cell-autonomous; it does not test whether astrocyte-secreted factors influence firing. Searches for S100B and secreted factors found no passage addressing that conclusion. (LLM, conf=0.75)

  Experimental — accuracy not yet measured

May combine two claims.

tPA is increased in cortical supragranular layers I-III but decreased in layers IV-V at P7 in the Fmr1 KO brain.

“Colocalising with GFAP, tPA is increased in cortical supragranular layers I-III but decreased in layers IV-V at P7 in the Fmr1 KO brain (Achuta et al., 2014).”

• cites Achuta et al., 2014 sourcePartly supported

  The section on altered tPA expression in developing Fmr1 KO mice (Fig. 4C,D; page unavailable) reports more tPA-positive cells in cortical layers I–III and fewer in layers IV–V at P7. The paper reports tPA colocalization with GFAP in differentiated progenitors and adult cortex, but does not establish that colocalization for the P7 cortical-layer finding. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Phospho-SMAD positive astrocytes are increased in Fmr1 KO cortex at P7, indicating increased BMP activity.

“Phospho-SMAD positive astrocytes are increased in Fmr1 KO cortex at P7, indicating increased bone morphogenetic protein (BMP) activity.”

• cites Caldwell et al., 2022 sourceSupported

May combine two claims.

Ca2+ signals in response to extracellular ATP in human FMR1 KO astrocytes have increased amplitude but neither the proportion of cells responding nor the duration of the response change.

“Ca2+ signals in response to extracellular adenosine triphosphate (ATP) in human FMR1 KO astrocytes have increased amplitude but neither the proportion of cells responding nor the duration of the response change (Ren et al., 2023).”

• cites Ren et al., 2023 sourcePartly supported

  The Results section, “Altered Ca2+ signaling in FXS-astrocytes” (page unavailable), reports increased ATP-response peak amplitude with no change in the proportion responding or response duration. Those measurements were made in patient-derived FXS hiPSC-astrocytes, not the separately described FMR1-KO hESC-derived astrocytes, so the claim's cell-type designation is not supported. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Regulation of astroglial transporter expression is strongly associated with astrocytic maturation and influenced by culturing conditions, which may explain that Ren and colleagues did not observe reduced glutamate uptake in human FMR1 KO astrocytes.

“Regulation of astroglial transporter expression is strongly associated with astrocytic maturation and influenced by culturing conditions (Schlag et al., 1998; Peteri et al., 2021), which may explain that Ren and colleagues (Ren et al., 2023) did not observe reduced glutamate uptake in human FMR1 KO astrocytes.”

• cites Schlag et al., 1998 sourceNot checked — no full text of the source
• cites Peteri et al., 2021 sourceCould not verify

  Split into 2 atoms — 0 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 2 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites Ren et al., 2023 sourceSupported

May combine two claims.

In a human FMR1 KO iPSC cortical model, KO NPCs produced larger organoids and displayed increased GFAP expression compared with isogenic controls.

“In a separate human FMR1 KO iPSC cortical model, KO NPCs produced larger organoids and displayed increased glial fibrillary acidic protein (GFAP) expression when compared with isogenic controls (Brighi et al., 2021).”

• cites Brighi et al., 2021 sourcePartly supported

  The Results section, ‘Development of a brain organoid-based FXS 3D disease model,’ reports that FMRP-KO organoids were larger and had increased GFAP staining compared with isogenic FMRP-WT organoids. However, the Methods section, ‘Generation of self-assembled brain organoids,’ says the organoids were generated from dissociated hiPSCs, not from KO neural progenitor cells (NPCs); the GFAP finding is reported for organoids, not specifically for NPCs. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

FMRP deficiency affects localization of mRNAs in astrocytes and particularly alters levels of mRNAs localized at astrocytic processes.

“FMRP deficiency affects localization of mRNAs in astrocytes and particularly alters levels of mRNAs localized at astrocytic processes.”

• cites Men et al., 2022 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

FMRP acts as an overall suppressor of protein synthesis by regulating nuclear-cytoplasmic translocation and translation of various mRNAs, many of which are associated with synapse function.

“FMRP acts as an overall suppressor of protein synthesis (Laggerbauer et al., 2001), a function which it achieves by regulating nuclear-cytoplasmic translocation (Feng et al., 1997; Kim et al., 2009) and translation of various mRNAs. Many of these RNAs are associated with synapse function (Darnell et al., 2011).”

• cites Laggerbauer et al., 2001 sourceNot checked — no full text of the source
• cites Feng et al., 1997 sourcePartly supported

  Feng et al. support the part of the sentence concerning nuclear–cytoplasmic movement: the ‘Nucleocytoplasmic shuttling and ribosome association of FMRP’ section reports FMRP in neuronal nuclei and nuclear pores. The Discussion describes its proposed role in carrying mRNAs to ribosomes and regulating translation as a hypothesis, not an established mechanism. The other citations, rather than Feng et al., are attached to the claims about overall suppression and synapse-associated RNAs. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites Darnell et al., 2011 sourceSupported

May combine two claims.

Absence of FMRP appears to influence the dynamics of astrocyte maturation, and some mechanisms may be shared with other neurodevelopmental disorders.

“Absence of FMRP appears to influence the dynamics of astrocyte maturation, and some of the mechanisms may be shared with other neurodevelopmental disorders (Caldwell et al., 2022).”

• cites Caldwell et al., 2022 sourceSupported

May combine two claims.

Secretion of TSP-1 is abnormally reduced from Fmr1 KO astrocytes, whereas NT-3 levels are increased in the secretome of Fmr1 KO astrocytes and in the Fmr1 KO prefrontal cortex compared with controls.

“Secretion of thrombospondin-1 (TSP-1) that as an extracellular matrix protein may induce cell adherence and induce synaptogenesis is also abnormally reduced from Fmr1 KO astrocytes (Cheng et al., 2016), whereas neurotrophin-3 (NT-3) levels are increased in the secretome of Fmr1 KO astrocytes as well as in the Fmr1 KO prefrontal cortex when compared with controls (Yang et al., 2012).”

• cites Cheng et al., 2016 sourceSupported
• cites Yang et al., 2012 sourcePartly supported

  The Results section, “High levels of NT-3 are released from Fmr1 KO astrocytes” (page unavailable), reports higher NT-3 in KO astrocyte-conditioned medium and in the cerebral cortex of young KO mice than in WT controls. It does not identify the cortex sampled for that comparison as prefrontal. The TSP-1 statement is cited to Cheng et al., not to Yang et al. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Orphan receptor GPR124 is differently expressed in FXS and control astrocytes and may represent a partner receptor that acts through WNT/β-catenin signaling, which is altered in FXS models.

“Orphan receptor GPR124 (Chen et al., 2019) is differently expressed in FXS and control astrocytes and may represent a partner receptor that acts through WNT/β-catenin signaling, which is altered in FXS models (Peteri et al., 2021).”

• cites Chen et al., 2019 sourceSupported
• cites Peteri et al., 2021 sourceSupported

May combine two claims.

Cortical expression of hevin is increased in P14 Fmr1 KO mice compared with WT controls, consistent with an increase in density of thalamocortical synapses when WT neurons are cultured with Fmr1 KO astrocytes.

“Also, cortical expression of hevin that is necessary for the formation of thalamocortical excitatory synapses (Kucukdereli et al., 2011; Risher et al., 2014) is increased in P14 Fmr1 KO mice compared with WT controls consistent with an increase in the density of thalamocortical synapses when WT neurons are cultured with Fmr1 KO astrocytes (Wallingford et al., 2017).”

• cites Wallingford et al., 2017 sourceSupported

May combine two claims.

Species-specific differences and differences in experimental approaches such as glutamate incubation time may explain different results in studies on astrocytic glutamate uptake.

“Species specific differences and differences in experimental approaches such as glutamate incubation time may explain different results in studies on astrocytic glutamate uptake (Higashimori et al., 2016; Ren et al., 2023).”

• cites Higashimori et al., 2016 sourceCould not verify

  The glutamate uptake assay methods (page unavailable) specify a six-minute incubation, and the results report reduced uptake in astrocyte-specific knockout mice. Our copy does not say that species differences or incubation time may explain differing results across studies; searches for those explanations found no such passage. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites Ren et al., 2023 sourcePartly supported

  The Results (page unavailable) contrast impaired glutamate uptake reported in mouse Fmr1-knockout astrocytes with no observed difference between human FXS and control astrocytes; the Discussion notes substantial human–rodent astrocyte differences. Experimental Procedures (page unavailable) specify a three-hour glutamate incubation, but the paper does not say that incubation time explains the differing findings. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

May combine two claims.

Expression of tissue plasminogen activator (tPA) is increased in differentiating Fmr1 KO neural progenitors, indicating increased tPA activity.

“Expression of tissue plasminogen activator (tPA) is increased in differentiating Fmr1 KO neural progenitors, indicating increased tPA activity (Achuta et al., 2014).”

• cites Achuta et al., 2014 sourcePartly supported

  The section on increased tPA expression in neural progenitor cells (page unavailable) reports more tPA-immunoreactive cells after differentiation of Fmr1 KO progenitors than wild-type controls. It does not establish that tPA enzymatic activity increased; the claim’s activity inference goes beyond the reported expression finding. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

In human FMR1 KO differentiating astrocytes, cyclin D1 is increased 2-fold, associating with reduced S phase duration in an otherwise unchanged cell cycle duration.

“Studying human FMR1 KO differentiating astrocyte cell cycle dynamics, Ren et al. (2023) observed 2-fold increased cyclin D1 associating with reduced S phase duration in an otherwise unchanged cell cycle duration.”

• cites Ren et al., 2023 sourcePartly supported

  The Results section (‘Altered cell cycle dynamics in FXS astrocytes’; page unavailable) reports a two-fold increase in cyclin D1, a shorter estimated S phase, and no significant change in total cell-cycle duration in immature human FXS hiPSC-derived astrocytes. The paper distinguishes these patient-derived cells from its FMR1-KO hESC-derived astrocytes; the cited results are not reported for the latter, so the claim's ‘FMR1 KO’ designation is imprecise. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

May combine two claims.

Reduction of several GABA receptor subunits in various brain regions associates with reduced expression of GABA metabolizing enzymes and reduced numbers of parvalbumin positive neurons in the Fmr1 KO mouse.

“Reduction of several GABA receptor subunits in various brain regions associates with reduced expression of GABA metabolizing enzymes and reduced numbers of parvalbumin (PV) positive neurons in the Fmr1 KO mouse (Gao et al., 2018; Van der Aa and Kooy, 2020).”

• cites Gao et al., 2018 sourcePartly supported

  Section 3 (page unavailable) reports reduced tonic GABAA receptor subunits associated with reduced tonic currents in an Fmr1 knockout mouse, but does not establish reductions of several subunits across various brain regions. Section 2 (page unavailable) discusses GABA metabolism without reporting reduced expression of its enzymes, and the searched passages do not report fewer parvalbumin-positive neurons. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites Van der Aa and Kooy, 2020 sourceNot checked — no full text of the source

May combine two claims.

FXS neurons showed a high frequency of short, spontaneous bursts and reduced persistent Na+ current in the presence of FXS astrocytes or media secreted by FXS astrocytes.

“FXS neurons showed a high frequency of short, spontaneous bursts and reduced persistent Na+ current in the presence of FXS astrocytes or media secreted by FXS astrocytes.”

• cites Das Sharma et al., 2023 sourcePartly supported

  The Results sections on astrocyte genotype and conditioned medium report frequent, short spontaneous bursts in FXS neurons with FXS astrocytes or FXS astrocyte-conditioned medium. The section on persistent sodium currents reports reduced INaP in FXS neurons co-cultured with FXS astrocytes, but does not establish that reduction for neurons grown in conditioned medium. Page numbers are unavailable in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

The Fmr1 knockout mouse model lacks FMRP and recapitulates the main FXS phenotype, including deficiency in learning and memory, social behavior, and sensory processing.

“The mouse model of FXS, the Fmr1 knockout (KO) mice, lacks FMRP and recapitulates the main phenotype, including deficiency in learning and memory, social behavior, and sensory processing (Bassell and Warren, 2008; Liu and Smith, 2009).”

• cites Bassell and Warren, 2008 sourcePartly supported

  The ‘Fragile X Phenotype Suggests FMRP Affects Dendritic mRNA function’ section (page unavailable) identifies Fmr1 KO mice as an FXS model and reports altered learning and behavior. The axonal-development section reports altered sensory-related plasticity and pain processing in these mice. Our copy does not specifically establish deficits in social behavior or memory, so the full list of deficiencies is not supported. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites Liu and Smith, 2009 sourcePartly supported

  The paper’s opening passage (section labeled Abstract; page unavailable) says Fmr1 knockout mice lack FMRP and show some learning impairments and social abnormalities comparable to those in people with FXS. It does not establish memory deficiency or impaired sensory processing in the knockout mice; its mention of low visual acuity concerns the background strain, not a knockout-specific deficit. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

These changes associated with increased GABA levels and increased glutamate decarboxylase in astrocytes, indicating increased GABA synthesis.

“These changes associated with increased GABA levels and increased glutamate decarboxylase in astrocytes, indicating increased GABA synthesis (Rais et al., 2022, preprint available).”

• cites Rais et al., 2022, preprint available sourceSupported

May combine two claims.

Loss of astrocytic FMRP recapitulated the reduced number of cortical PV cells and reduced synaptic GABAA receptor subunits.

“Loss of astrocytic FMRP recapitulated the reduced number of cortical PV cells and reduced synaptic GABAA receptor subunits (Rais et al., 2022, preprint available).”

• cites Rais et al., 2022, preprint available sourceSupported

May combine two claims.

Astrocyte-specific Fmr1 KO mouse displays reduced expression of astrocytic glutamate transporter GLT-1, leading to reduced astrocytic uptake of extracellular glutamate and increased cortical neuronal excitability.

“Astrocyte-specific Fmr1 KO mouse displays reduced expression of the astrocytic glutamate transporter GLT-1, which leads to reduced astrocytic uptake of extracellular glutamate and increased cortical neuronal excitability (Higashimori et al., 2016).”

• cites Higashimori et al., 2016 sourceSupported

May combine two claims.

TLR4/MyD88-mediated induction of IL-6 is overactive in Fmr1 KO astrocytes, implicating involvement of inflammatory factors and suggesting alteration in TLR4/MyD88/PI3K interactions in FXS astrocytes.

“TLR4/MyD88-mediated induction of IL-6 is overactive in Fmr1 KO astrocytes (Krasovska and Doering, 2018), implicating involvement of inflammatory factors and suggesting alteration in TLR4/MyD88/PI3K interactions (Laird et al., 2009) in FXS astrocytes.”

• cites Krasovska and Doering, 2018 sourcePartly supported

  The Abstract reports elevated secreted IL-6 in FMR1 KO astrocytes, and the Discussion (WT and FMR1 KO Astrocyte Response to Immunological Challenges; page unavailable) reports that TLR4 antagonism reduced their IL-6 secretion. But the paper does not establish overactive MyD88-mediated induction in KO astrocytes: it cites another study for MyD88 dependence and reports that KO cells responded less than WT cells to some TLR4 stimuli. The later suggestion about PI3K interactions is attached to a different citation in the citing sentence. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites Laird et al., 2009 sourceNot checked — no full text of the source

May combine two claims.

Astrocytes in the cerebellum of Fmr1 KO mice display chronic, persistent activation with little or no activation of microglia.

“Pacey et al. (2015) showed that astrocytes in the cerebellum of Fmr1 KO mice display chronic, persistent activation with little or no activation of microglia.”

• cites Pacey et al., 2015 sourceSupported

May combine two claims.

IL-1β treatment increases GFAP and chemokine CCL5 mRNA expression more in human FXS iPSC-derived astrocytes than in control astrocytes, suggesting that FXS astrocytes are characterized by increased sensitivity to reactivity.

“IL-1β treatment increases GFAP and chemokine CCL5 mRNA expression more in human FXS iPSC-derived astrocytes than in control astrocytes (Talvio et al., 2023), suggesting that FXS astrocytes are characterized by increased sensitivity to reactivity.”

• cites Talvio et al., 2023 sourceSupported

May combine two claims.

In human FXS iPSC-derived astrocytes, L-type calcium channel-dependent Ca2+ responses to high extracellular K+ were reduced compared with controls and showed strong inverse correlation with ACM uPA levels, demonstrating that altered Ca2+ signaling in FXS astrocytes modulates neuronal plasticity.

“In human FXS iPSC-derived astrocytes, L-type calcium channel-dependent Ca2+ responses to high extracellular K+ were reduced when compared with controls and these responses showed strong inverse correlation with ACM uPA levels (Peteri et al., 2021), demonstrating that altered Ca2+ signaling in FXS astrocytes modulates neuronal plasticity.”

• cites Peteri et al., 2021 sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

Cholesterol levels did not differ between human or mouse FMRP-deficient and control astrocyte conditioned medium, suggesting that astrocytes maintained extracellular cholesterol homeostasis to avoid cholesterol toxicity.

“Here, cholesterol levels did not differ between human or mouse FMRP-deficient and control astrocyte conditioned medium, suggesting that astrocytes maintained extracellular cholesterol homeostasis to avoid cholesterol toxicity (Adachi et al., 2022; Talvio et al., 2023).”

• cites Adachi et al., 2022 sourcePartly supported

  The Results section on astrocyte viability reports increased cell death under high extracellular cholesterol, and the Discussion says cholesterol-induced Ca oscillations help astrocytes survive that load. The paper does not show that astrocytes maintain extracellular cholesterol homeostasis; it also does not compare cholesterol levels in conditioned medium from FMRP-deficient and control astrocytes. Page numbers were not provided in our copy. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites Talvio et al., 2023 sourceSupported

May combine two claims.

GFAP, TNFR2, and S100B are increased in the adult Fmr1 KO brain.

“GFAP, TNFR2, and S100B were increased in the adult Fmr1 KO brain (Pacey et al., 2015).”

• cites Pacey et al., 2015 sourcePartly supported

  The Results report increased GFAP in the adult Fmr1 KO cerebellar cortex, TNFR2 in its deep white matter, and S100β in its molecular and Purkinje cell layers. The evidence supports the three increases in the cerebellum, but not a broader claim about the adult brain. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Abnormalities associated with FXS astrocytes include differentiation of central nervous system cell populations, maturation and regulation of synapses, and synaptic glutamate balance.

“Abnormalities associated with FXS astrocytes include differentiation of central nervous system cell populations, maturation and regulation of synapses, and synaptic glutamate balance.”

May combine two claims.

Studies of mouse Fmr1 KO astrocytes and human stem cell-derived astrocytes have shown a number of differences between FMRP-deficient and healthy control astrocytes, including changes in factors secreted from astrocytes as well as transcriptomics and protein expression profiles, lipidomics, Ca2+ signaling, and inflammatory activity of astrocytes.

“As summarized in Figure 1, studies of the mouse Fmr1 KO astrocytes and human stem cell-derived astrocytes have shown a number of differences between FMRP-deficient and healthy control astrocytes, including changes in factors secreted from astrocytes as well as transcriptomics and protein expression profiles, lipidomics, Ca2+ signaling, and inflammatory activity of astrocytes.”

May combine two claims.

Changes of FXS astrocytes impact brain homeostasis and function both during development and in the adult brain and offer opportunities for novel types of approaches for intervention.

“Changes of FXS astrocytes impact the brain homeostasis and function both during development and in the adult brain and offer opportunities for novel types of approaches for intervention.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Astrocytes have an important role in neuronal maturation and synapse function in the brain.

“Astrocytes have an important role in neuronal maturation and synapse function in the brain.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A CGG trinucleotide repeat expansion in the 5′ untranslated region of the FMR1 gene is the most common genetic cause behind FXS.

“A CGG trinucleotide repeat expansion in the 5′ untranslated region of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is the most common genetic cause behind FXS (Fu et al., 1991; Verkerk et al., 1991).”

• cites Fu et al., 1991Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Verkerk et al., 1991 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

FMRP is an RNA binding protein mainly expressed in the central nervous system and gonads, and to a lesser extent in other tissues.

“FMRP is an RNA binding protein (Siomi et al., 1993) that is mainly expressed in the central nervous system (CNS) and gonads, and to lesser extent in other tissues (Hinds et al., 1993).”

• cites Siomi et al., 1993 sourceNot checked — no full text of the source
• cites Hinds et al., 1993 sourceNot checked — no full text of the source

May combine two claims.

GABAergic circuits and GABA homeostasis are dysregulated in the absence of FMRP.

“In addition to the glutamatergic system, GABAergic circuits and GABA homeostasis are dysregulated in the absence of FMRP.”

May combine two claims.

Current therapeutic strategies of FXS remain symptomatic and no specific treatment has reached clinical use.

“Despite several promising therapeutic targets and success with animal models, current therapeutic strategies of FXS remain symptomatic and no specific treatment has reached clinical use.”

Probably not a substantial claim: may not pass S3 (load-bearing).

FMRP expression in astrocytes shows highest levels at the time of vital growth, stabilization, and maturation of synapses, declining thereafter.

“Its expression in astrocytes shows highest levels at the time of vital growth, stabilization, and maturation of synapses, declining thereafter (Pacey and Doering, 2007).”

• cites Pacey and Doering, 2007 sourceNot checked — no full text of the source

May combine two claims.

mGluR5 regulates GLT-1 expression in astrocytes, and reduced mGluR5 expression has been found in both human and mouse FMRP-deficient astrocytes.

“mGluR5 regulates GLT-1 expression in astrocytes and reduced mGluR5 expression has been found both in human and mouse FMRP-deficient astrocytes (Higashimori et al., 2013; Men et al., 2020).”

• cites Higashimori et al., 2013 sourceNot checked — no full text of the source
• cites Men et al., 2020 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S2 (checkable), S4 (based). May combine two claims.

Many treatment approaches for FXS are likely complicated by glial function, and future research on astrocytes has potential to benefit the development of therapies.

“Many of the aforementioned treatment approaches for FXS are likely complicated by glial function, and future research on astrocytes has potential to benefit the development of therapies.”

Classified as probably not a substantial claim. May combine two claims.

Over 200 CGG repeats in FMR1 lead to embryonic methylation of the promoter, subsequent silencing of the gene, and lack of FMRP.

“Repeats less than 55 are in the benign range, whereas over 200 repeats lead to embryonic methylation of the promoter, subsequent silencing of the gene, and therefore lack of the FMR1 protein (FMRP, Sutcliffe et al., 1992).”

• cites Sutcliffe et al., 1992 sourceNot checked — no full text of the source

May combine two claims.

Astroglial glutamate transporters modulate activation of neuronal mGluR1/5, providing a mechanism that may underlie enhanced neuronal mGluR5 activation in FXS.

“Astroglial glutamate transporters modulate activation of neuronal mGluR1/5 providing a mechanism, which may underlie enhanced neuronal mGluR5 activation in FXS.”

May combine two claims.

Therapeutic approaches for FXS have been based on disturbed mechanisms observed to affect neuron function, and the role of non-neuronal cells in these processes has been ignored.

“Therapeutic approaches have been based on disturbed mechanisms observed to affect neuron function and the role of non-neuronal cells in these processes has been ignored.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

In the CNS, FMRP is expressed in neurons and during development in glial cells.

“In the CNS, it is expressed in neurons and during development in glial cells.”

• cites Pacey and Doering, 2007 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Fmr1 knockout murine models facilitate replication of results in vivo.

“the Fmr1 KO murine models facilitate replication of results in vivo”

• AssumptionRests on an assumption: The Fmr1 knockout mouse model of fragile X syndrome parallels the phenotype of fragile X syndrome.

May combine two claims.

Astrocytes express FMRP during development, and its absence influences the way astrocytes differentiate in both human and murine models of FXS.

“Astrocytes express FMRP during development (Pacey and Doering, 2007; Gholizadeh et al., 2015), and its absence influences the way astrocytes differentiate in both human and murine models of FXS.”

• cites Pacey and Doering, 2007 sourceNot checked — no full text of the source
• cites Gholizadeh et al., 2015 sourceNot checked — no full text of the source

May combine two claims.

Studies on Fmr1 KO mouse astrocytes have revealed alterations in astrocyte released factors that differentially regulate excitatory synapse development and how astrocytes influence glutamatergic signaling in the absence of FMRP.

“Astrocytes sense and respond to changes in the extracellular milieu, and studies on the Fmr1 KO mouse astrocytes have revealed alterations in astrocyte released factors that differentially regulate excitatory synapse development and how astrocytes influence glutamatergic signaling in the absence of FMRP.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Cholesterol does not pass the blood brain barrier, so the CNS pool is maintained locally.

“Cholesterol does not pass the blood brain barrier, so the CNS pool is maintained locally.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Altered cholesterol balance in Fmr1 KO mouse astrocytes together with increased levels of PUFA may contribute to the capacity of astrocytes to maintain extracellular homeostasis by modulating membrane properties and influencing receptor functions.

“Altered cholesterol balance in Fmr1 KO mouse astrocytes together with increased levels of PUFA may contribute to the capacity of astrocytes to maintain extracellular homeostasis by modulating membrane properties and influencing receptor functions.”