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Cited by 242Genetics and Neurodevelopmental DisordersAutism Spectrum Disorder ResearchGenomics and Rare Diseases

A suppressor screen in Mecp2 mutant mice implicates cholesterol metabolism in Rett syndrome

Open access
Buchovecky, Christie M, Turley, Stephen D, Brown, Hannah M, Kyle, Stephanie M, McDonald, Jeffrey G, Liu, Benny, Pieper, Andrew A, Huang, Wenhui +4 more·2013·Nature Genetics
DOI 10.1038/ng.2714PMC PMC3837522
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Abstract

Mutations in MECP2, encoding methyl CpG-binding protein 2, cause Rett syndrome, the most severe autism spectrum disorder. Re-expressing Mecp2 in symptomatic Mecp2-null mice markedly improves function and longevity, providing hope that therapeutic intervention is possible in humans. To identify pathways in disease pathology for therapeutic intervention, we carried out a dominant N-ethyl-N-nitrosourea (ENU) mutagenesis suppressor screen in Mecp2-null mice and isolated five suppressors that ameliorate the symptoms of Mecp2 loss. We show that a stop codon mutation in Sqle, encoding squalene epoxidase, a rate-limiting enzyme in cholesterol biosynthesis, underlies suppression in one line. Subsequently, we also show that lipid metabolism is perturbed in the brains and livers of Mecp2-null male mice. Consistently, statin drugs improve systemic perturbations of lipid metabolism, alleviate motor symptoms and confer increased longevity in Mecp2 mutant mice. Our genetic screen therefore points to cholesterol homeostasis as a potential target for the treatment of patients with Rett syndrome.

AI snapshot

Written from the paper’s full text.

TL;DR

A dominant ENU suppressor screen in Mecp2 null mice identified five suppressor loci, including a nonsense mutation in squalene epoxidase (Sqle), linking cholesterol biosynthesis to Rett syndrome pathology. Genetic and statin-mediated reduction of cholesterol synthesis improved motor symptoms and longevity in Mecp2 mutant mice.

Key findings

  • The screen isolated five inherited suppressors of Mecp2 loss; all increased lifespan by at least 3 weeks from the average 50% lethality (L50) time point. Linkage was significant for Sum1 on chromosome 16 (LOD 4.82), Sum2 on chromosome 3 (LOD 3.61), Sum3 on chromosome 15 (LOD 3.03), and Sum4 on chromosome 7 (LOD 3.40); Sum5 had a maximum LOD of 2.86 and no confirmed map location.
  • Exome sequencing identified a nonsense mutation in Sqle (c.1195C>T, p.Arg399Ter) underlying Sum3 suppression. Homozygous SqleSum3Jus mice died prior to birth at E8.5; Sqle expression was reduced by nearly 50% in SqleSum3Jus/+ brains at P70, with decreased desmosterol and lanosterol.
  • Mecp2 null males showed abnormal cholesterol metabolism: Cyp46a1 expression was increased 38% over wild type in 129.Mecp2tm1.1Bird null brain at P28 (p=.02); whole-brain cholesterol synthesis was decreased by 23% per gram; liver triglycerides were increased at P56 (p=.003); and serum cholesterol, LDL-cholesterol, and triglycerides were elevated in 129.Mecp2tm1.1Bird/Y mice (p≤.01) but not in B6.Mecp2tm1.1Jae/Y mice.
  • Fluvastatin and lovastatin improved motor performance and open-field activity; fluvastatin lowered cholesterol, improved health scores, and increased lifespan, but did not improve breathing irregularity or acoustic startle. Female 129.Mecp2tm1.1Bird/+ mice had 164% higher liver lipid content than wild type at 8 months, and fluvastatin reduced liver lipid accumulation to wild-type levels.

Methods

  • Dominant ENU mutagenesis screen: C57BL/6J males were treated with ENU and mated to 129.Mecp2tm1.1Bird/+ females. Of 2,963 G1 animals weaned, 1,522 were males and 679 were Mecp2tm1.1Bird/Y; 25 males were bred to assess heritability, litters were obtained from seven, and five suppressor lines were established.
  • Mapping used an Illumina medium-density SNP panel and MIT markers; exome capture and massively parallel sequencing identified variants. Lipid/sterol analyses included tandem mass spectrometry, gas-liquid chromatography, and in vivo 3H2O incorporation; gene expression was measured by real-time RT-PCR.
  • Behavioral and physiological assays included rotarod, open-field activity, plethysmography, and acoustic startle. Drug studies administered fluvastatin or lovastatin at specified doses and schedules; statistics used R/qtl LOD scores, Kaplan-Meier log-rank tests, t-tests, and ANOVA with post hoc adjustments.

Limitations

  • Stated: the findings “do not comprise a pre-clinical trial”; none of the suppressors eliminated symptoms entirely, suggesting combination therapy will be required; the precise mechanisms by which statins alter brain cholesterol are unknown; pinpointing the cause of peripheral dyslipidemia is a future endeavor; full understanding of lipid homeostasis in all organs remains to be uncovered; peripheral dyslipidemia may be a biomarker in only a subset of RTT patients; moderate statin doses were effective while 10× doses were detrimental, requiring further optimization; and the Sum5 locus was not confirmed.
  • Evident from the text: all experimental evidence comes from mouse models, with no human RTT patient intervention reported; allele- and strain-specific differences limit generalization; and statin effects on breathing and startle were not improved.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/ng.2714

Cites

66 of 66 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

50 of 73 cited sources checked · 22 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Male Mecp2/Y mice have a fully penetrant phenotype.

    “Although female Mecp2/+ mice show phenotypic variance in part due to random X-chromosome inactivation, male Mecp2/Y mice have a fully penetrant phenotype.”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites [3] Guy, J., Hendrich, B., Holmes, M., Martin, J.E. & Bird, A. A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome. Nat. Genet. 27, 322–326 (2001). source
    • cites [4] Shepherd, G.M. & Katz, D.M. Synaptic microcircuit dysfunction in genetic models of neurodevelopmental disorders: focus on Mecp2 and Met. Curr. Opin. Neurobiol. 21, 827–833 (2011). source

      The section on neocortical microcircuits in MeCP2 deficiency models (page not provided) reports abnormalities in Mecp2-null mice, supporting the claim that the model has a phenotype. It does not state that every male Mecp2/Y mouse is affected or establish full penetrance. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
    • cites [5] Kavalali, E.T., Nelson, E.D. & Monteggia, L.M. Role of MeCP2, DNA methylation, and HDACs in regulating synapse function. J. Neurodev. Disord. 3, 250–256 (2011). source

      The Rett syndrome section (page unavailable) reports that constitutive MeCP2 knockout mice recapitulate some neurological symptoms. The synaptic-transmission table also lists abnormalities in male MeCP2−/y mice, but neither passage establishes that every male mouse develops a phenotype; the claim of full penetrance is unsupported. (LLM, conf=0.78)

      Experimental — accuracy not yet measured
  • Premisecitation

    When neurons require cholesterol turnover or accumulate too much cholesterol or its intermediates, Cyp46a1 hydroxylates cholesterol to produce 24S-hydroxycholesterol, allowing egress by one-way diffusion into the circulation across the blood brain barrier.

    “When neurons require cholesterol turnover or accumulate too much cholesterol or its intermediates, the cytochrome P450 oxidase Cyp46a1 hydroxylates cholesterol to produce 24S-hydroxycholesterol (24SOHC), allowing for egress by one-way diffusion into the circulation across the BBB (Fig. 4a)31.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [31] Russell, D.W., Halford, R.W., Ramirez, D.M., Shah, R. & Kotti, T. Cholesterol 24-hydroxylase: an enzyme of cholesterol turnover in the brain. Annu. Rev. Biochem. 78, 1017–1040 (2009). source

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

      Experimental — accuracy not yet measured
  • Premisecitation

    Re-expressing Mecp2 in symptomatic Mecp2 null mice dramatically improves function and longevity.

    “Re-expressing Mecp2 in symptomatic Mecp2 null mice dramatically improves function and longevity, providing hope that therapeutic intervention is possible in humans.”
    • Also stated in: § Abstract · plain
      “Restoration of Mecp2 expression in mutant mice after the onset of symptoms rescues the neurological deficits, including motor function, and significantly prolongs survival6.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Guy, J., Gan, J., Selfridge, J., Cobb, S. & Bird, A. Reversal of neurological defects in a mouse model of Rett syndrome. Science 315, 1143–1147 (2007). source
  • Premisecitation

    Mouse models recapitulate many of the symptoms of RTT.

    “Mouse models recapitulate many of the symptoms of RTT and their study has provided insight into the physiological basis of disease3–5.”
    Quote in the paperSubstantial claim3 of 3 sources checked
    • cites [3] Guy, J., Hendrich, B., Holmes, M., Martin, J.E. & Bird, A. A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome. Nat. Genet. 27, 322–326 (2001). source
    • cites [4] Shepherd, G.M. & Katz, D.M. Synaptic microcircuit dysfunction in genetic models of neurodevelopmental disorders: focus on Mecp2 and Met. Curr. Opin. Neurobiol. 21, 827–833 (2011). source
    • cites [5] Kavalali, E.T., Nelson, E.D. & Monteggia, L.M. Role of MeCP2, DNA methylation, and HDACs in regulating synapse function. J. Neurodev. Disord. 3, 250–256 (2011). source
  • Interpretationcitation

    Statin drugs likely alter brain cholesterol through indirect effects of altered systemic lipid metabolism.

    “The precise mechanisms by which statin drugs alter brain cholesterol are unknown, but likely include indirect effects of altered systemic lipid metabolism48,49.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [48] Cibičkova, L. Statins and their influence on brain cholesterol. J. Clin. Lipidol. 5, 373–379 (2011). source
    • cites [49] Stranahan, A.M., Cutler, R.G., Button, C., Telljohann, R. & Mattson, M.P. Diet-induced elevations in serum cholesterol are associated with alterations in hippocampal lipid metabolism and increased oxidative stress. J. Neurochem. 118, 611–615 (2011). source

      The Abstract reports that diet-induced elevations in peripheral cholesterol in rats accompanied increased hippocampal cholesterol, suggesting crosstalk between systemic and brain lipid metabolism. It does not study statin drugs or establish that their effects on brain cholesterol occur indirectly through systemic lipid changes. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Classified as probably not a substantial claim. 25
  • May combine two claims. 24
  • The quote only partly states this claim. 2

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

    Premisecitation

    Two alleles of Mecp2 are primarily used as mouse models of RTT: Mecp2tm1.1Bird, a null mutation, and Mecp2tm1.1Jae, which expresses low levels of a truncated protein.

    “Two alleles of Mecp2 are primarily used as mouse models of RTT: Mecp2tm1.1Bird, a null mutation3, and Mecp2tm1.1Jae, which expresses low levels of a truncated protein32.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [3] Guy, J., Hendrich, B., Holmes, M., Martin, J.E. & Bird, A. A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome. Nat. Genet. 27, 322–326 (2001). source
    • cites [32] Chen, R.Z., Akbarian, S., Tudor, M. & Jaenisch, R. Deficiency of methyl-CpG binding protein-2 in CNS neurons results in a Rett-like phenotype in mice. Nat. Genet. 27, 327–331 (2001). source

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

    Premisecitation

    To facilitate proper neurotransmitter release and dendrite remodeling, neuronal membranes constantly require turnover to eliminate cholesterol that has been adulterated by reactive oxygen species, byproducts of their high rate of metabolism.

    “To facilitate proper neurotransmitter release and dendrite remodeling, neuronal membranes constantly require turnover to eliminate cholesterol that has been adulterated by reactive oxygen species, byproducts of their high rate of metabolism30.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [30] Dietschy, J.M. Central nervous system: cholesterol turnover, brain development and neurodegeneration. Biol. Chem. 390, 287–293 (2009). source

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

      Experimental — accuracy not yet measured

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

    Premisecitation

    Genetic modifier screens are commonly applied to identify genes that act in developmental or biochemical pathways in fruit flies, worms, and bacteria, but this approach is rare in the mouse.

    “Genetic modifier screens are commonly applied to identify genes that act in developmental or biochemical pathways in fruit flies, worms, and bacteria10; however, this approach is rare in the mouse11,12.”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [10] St Johnston, D. The art and design of genetic screens: Drosophila melanogaster. Nature Rev. Genet. 3, 176–188 (2002). source
    • cites [11] Carpinelli, M.R. et al. Suppressor screen in Mpl−/− mice: c-Myb mutation causes supraphysiological production of platelets in the absence of thrombopoietin signaling. Proc. Natl. Acad. Sci. USA 101, 6553–6558 (2004). source
    • cites [12] Matera, I. et al. A sensitized mutagenesis screen identifies Gli3 as a modifier of Sox10 neurocristopathy. Hum. Mol. Genet. 17, 2118–2131 (2008). source

  • May combine two claims.

    Premisecitation

    Restoration of Mecp2 expression in mutant mice after the onset of symptoms rescues the neurological deficits, including motor function, and significantly prolongs survival.

    “Restoration of Mecp2 expression in mutant mice after the onset of symptoms rescues the neurological deficits, including motor function, and significantly prolongs survival6.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Guy, J., Gan, J., Selfridge, J., Cobb, S. & Bird, A. Reversal of neurological defects in a mouse model of Rett syndrome. Science 315, 1143–1147 (2007). source

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

    Premisecitation

    Only one other null eukaryotic mutation of Sqle has been identified, resulting in an inability for plants to tolerate drought stress.

    “Only one other null eukaryotic mutation of Sqle has been identified, resulting in an inability for plants to tolerate drought stress26,27.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [26] Posé, D. & Botella, M.A. Analysis of the Arabidopsis dry2/sqe1-5 mutant suggests a role for sterols in signaling. Plant Signal. Behav. 4, 873–874 (2009). source
    • cites [27] Posé, D. et al. Identification of the Arabidopsis dry2/sqe1-5 mutant reveals a central role for sterols in drought tolerance and regulation of reactive oxygen species. Plant J. 59, 63–76 (2009). source

      The section on drought hypersensitivity reports that the Arabidopsis dry2 mutant is extremely sensitive to dehydration, and the section identifying DRY2 as a squalene epoxidase links that phenotype to SQE1. But the paper calls dry2/sqe1-5 a hypomorphic allele, not a null mutation. It also discusses a separate loss-of-function allele, sqe1-3, without reporting its drought tolerance or establishing that it is the only other null eukaryotic SQE mutation. Page numbers were not available in our copy. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Cholesterol homeostasis is maintained by negative feedback regulation of genes and their encoded enzymes in the pathway, including the rate-limiting enzymes HMGCR and SQLE.

    “Cholesterol homeostasis is maintained by negative feedback regulation of genes and their encoded enzymes in the pathway, including the rate limiting enzymes HMG CoA reductase (HMGCR) and SQLE20–22.”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [20] Gill, S., Stevenson, J., Kristiana, I. & Brown, A.J. Cholesterol-dependent degradation of squalene monooxygenase, a control point in cholesterol synthesis beyond HMG-CoA reductase. Cell Metab. 13, 260–273 (2011). source

      The Introduction identifies HMGCR as a major rate-limiting control point, and the passage on cholesterol treatment reports reduced mRNA levels for both HMGCR and SQLE (Abstract, Figure 1E). The paper also reports cholesterol-dependent degradation of SQLE's enzyme, but describes SQLE as a *possible* control point that may become rate-limiting under acute cholesterol treatment—not an established rate-limiting enzyme generally. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [21] Cory, E.J., Russey, W.E. & Ortiz de Montellano, P.R. 2,3-oxidosqualene, an intermediate in the biological synthesis of sterols from squalene. J. Am. Chem. Soc. 88, 4750–4751 (1966). source
    • cites [22] Yamamoto, S. & Bloch, K. Studies on squalene epoxidase of rat liver. J. Biol. Chem. 245, 1670–1674 (1970). source

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

    Premisecitation

    Inflammation is a key manifestation of Mecp2 mutation in non-neural cells.

    “Inflammation is a key manifestation of Mecp2 mutation in non-neural cells14.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [14] Derecki, N.C. et al. Wild-type microglia arrest pathology in a mouse model of Rett syndrome. Nature 484, 105–109 (2012). source

      In the indexed passage labeled Abstract (page not supplied), the paper reports that Mecp2-null microglia have impaired responses to immunological stimuli and reduced phagocytic capacity. This supports altered immune-cell function, but the paper does not identify inflammation as a key manifestation of Mecp2 mutation in non-neural cells. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

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

    Premisecitation

    SQLE catalyzes the first oxygenation reaction in the committed production of cholesterol.

    “SQLE catalyzes the first oxygenation reaction in the committed production of cholesterol, an essential lipid either supplied by diet or synthesized from acetate by a complex pathway18,19.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [18] Jurevics, H.A., Kidwai, F.Z. & Morell, P. Sources of cholesterol during development of the rat fetus and fetal organs. J. Lipid Res. 38, 723–733 (1997). source
    • cites [19] Zlokovic, B.V. The blood-brain barrier in health and chronic neurodegenerative disorders. Neuron 57, 178–201 (2008). source

      The Introduction discusses cholesterol in blood–brain barrier membrane rafts, not cholesterol biosynthesis. Searches for SQLE, squalene epoxidase, the first oxygenation reaction, and synthesis from acetate found no passage addressing the attributed claim. Page numbers were not available in our copy. (LLM, conf=0.76)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Mecp2 null males are normal at birth and weaning, but develop limb clasping, tremors, lethargy and abnormal breathing, symptoms that progressively worsen until death at 6-16 weeks of age.

    “Null males are normal at birth and weaning, but develop limb clasping, tremors, lethargy and abnormal breathing, symptoms that progressively worsen until death at 6 – 16 weeks of age.”
    Quote in the paperSubstantial claim3 of 3 sources checked
    • cites [3] Guy, J., Hendrich, B., Holmes, M., Martin, J.E. & Bird, A. A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome. Nat. Genet. 27, 322–326 (2001). source

      The phenotype description reports no initial symptoms, followed by hindlimb clasping, irregular breathing, reduced movement and deterioration ending in death at approximately 54 days. It does not report tremors or establish a 6–16-week age-at-death range. Figure 3a (p. 324) also shows that Mecp2-null males were significantly smaller than wild-type littermates from around weaning, qualifying the claim that they were normal at weaning. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [4] Shepherd, G.M. & Katz, D.M. Synaptic microcircuit dysfunction in genetic models of neurodevelopmental disorders: focus on Mecp2 and Met. Curr. Opin. Neurobiol. 21, 827–833 (2011). source

      The Neocortical microcircuits section says changes in Mecp2-null mice are evident at week 2, before overt symptoms, and grow stronger by weeks 3–4. The Synaptic dysfunction in respiratory networks section discusses breathing abnormalities in the mouse models. Neither section supports the full symptom list, normality at birth and weaning, or death at 6–16 weeks; page numbers are unavailable in our copy. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [5] Kavalali, E.T., Nelson, E.D. & Monteggia, L.M. Role of MeCP2, DNA methylation, and HDACs in regulating synapse function. J. Neurodev. Disord. 3, 250–256 (2011). source

      The Rett syndrome section (page unavailable) says constitutive MeCP2 knockout mice develop some neurological symptoms and die early in postnatal development. It does not specify that null males are normal at birth and weaning, list limb clasping, tremors, lethargy or abnormal breathing, or give a death range of 6–16 weeks. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    MECP2 plays roles in the postnatal maturation and/or maintenance of neuronal properties and circuits.

    “Therefore, MECP2 plays roles in the postnatal maturation and/or maintenance of neuronal properties and circuits4.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [4] Shepherd, G.M. & Katz, D.M. Synaptic microcircuit dysfunction in genetic models of neurodevelopmental disorders: focus on Mecp2 and Met. Curr. Opin. Neurobiol. 21, 827–833 (2011). source

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

    Premisecitation

    Statin drugs regulate systemic cholesterol through two mechanisms: by inhibiting HMGCR and by modifying liver uptake of serum LDL and triglycerides.

    “Statin drugs regulate systemic cholesterol through two mechanisms: by inhibiting HMGCR and by modifying liver uptake of serum LDL and triglycerides38.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [38] García-Sabina, A., Gulin-Davila, J., Sempere-Serrano, P., Gonzalez-Juanatey, C. & Martinez-Pacheco, R. Specific considerations on the prescription and therapeutic interchange of statins. Farm. Hosp. 36, 97–108 (2012). source

      The Introduction says statins inhibit HMG-CoA reductase and increase hepatocyte receptor expression, leading to greater removal of LDL cholesterol from circulating blood. It also says statins lower triglyceride levels, but does not describe this as increased liver uptake of triglycerides. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Promoter regions of lipid/cholesterol homeostasis genes, including Sqle, appear to be targets of HDAC3 in the liver.

    “Interestingly, the promoter regions of lipid/cholesterol homeostasis genes, including Sqle, appear to be targets of HDAC3 in the liver55.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [55] Knutson, S.K. et al. Liver-specific deletion of histone deacetylase 3 disrupts metabolic transcriptional networks. EMBO J. 27, 1017–1028 (2008). source

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

    Premisecitation

    Even small perturbations of cholesterol metabolism can have large effects on neuronal function, disrupting normal development and contributing to aging disorders including Huntington and Alzheimer disease.

    “Even small perturbations of cholesterol metabolism can have large effects on neuronal function, disrupting normal development41,42, and contributing to aging disorders including Huntington and Alzheimer disease43.”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [41] Keber, R. et al. Mouse knockout of the cholesterogenic cytochrome P450 lanosterol 14α-demethylase (Cyp51) resembles Antley-Bixler syndrome. J. Biol. Chem. 286, 29086–29097 (2011). source

      The Discussion (page unavailable) links disrupted cholesterol synthesis and sterol intermediates to embryonic developmental defects in Cyp51-knockout mice. It does not establish that small perturbations have large effects on neuronal function. The Huntington and Alzheimer disease clause carries a separate citation (43), so it is not assessed against this source. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [42] Waterham, H.R. Defects of cholesterol biosynthesis. FEBS Lett. 580, 5442–5449 (2006). source
    • cites [43] Björkhem, I. & Hansson, M. Cerebrotendinous xanthomatosis: an inborn error in bile acid synthesis with defined mutations but still a challenge. Biochem. Biophys. Res. Commun. 396, 46–49 (2010). source

  • May combine two claims.

    Premisecitation

    Loss of HDAC3 in liver cells leads to metabolic syndrome and FLD.

    “its loss in liver cells leads to metabolic syndrome and FLD56,57.”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [56] Sun, Z. et al. Hepatic Hdac3 promotes gluconeogenesis by repressing lipid synthesis and sequestration. Nat. Med. 18, 934–942 (2012). source

      The Results sections on hepatic Hdac3 deletion report severe hepatosteatosis in mice, supporting the fatty liver disease (FLD) portion. They do not report that the mice developed metabolic syndrome; instead, the section on glucose output and insulin sensitivity reports lower fasting glucose and insulin and improved insulin sensitivity despite the fatty liver. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
    • cites [57] Feng, D. et al. A circadian rhythm orchestrated by histone deacetylase 3 controls hepatic lipid metabolism. Science 331, 1315–1319 (2011). source

      The paper reports that deleting HDAC3 in mouse liver caused marked lipid accumulation and a fatty liver phenotype, supporting the FLD portion. It mentions metabolic syndrome as background in relation to night-shift work, but does not report that hepatic HDAC3 loss causes metabolic syndrome. The supplied copy labels the relevant passage “Abstract” and provides no page number. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

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

    Premisecitation

    Microglia recycle neuronal cholesterol during dendrite pruning.

    “Furthermore, microglia, which function as brain macrophages, recycle neuronal cholesterol during dendrite pruning39, and replacing mutant with wild type microglia via bone marrow transfer ameliorated RTT symptoms in Mecp2 null mice13.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [39] Osterweil, E.K. et al. Lovastatin corrects excess protein synthesis and prevents epileptogenesis in a mouse model of fragile X syndrome. Neuron 77, 243–250 (2013). source

      The Results passage on hippocampal-slice epileptogenesis and the Discussion passage on fragile X symptoms address lovastatin, protein synthesis, and seizures, not microglia or cholesterol recycling. Searches for microglia, neuronal cholesterol, and dendrite pruning found no passage in our copy addressing the attributed claim. (LLM, conf=0.76)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation

    Perturbations in lipid homeostasis may influence both neurological and non-neurological RTT symptoms, including abnormal responses to stress, high anxiety levels, and bone anomalies.

    “Sterols are the precursors of steroid hormones, bile acids and vitamin D; thus, perturbations in lipid homeostasis may influence both neurological and non-neurological RTT symptoms, including abnormal responses to stress, high anxiety levels, and bone anomalies52.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [52] Percy, A.K. Rett syndrome: exploring the autism link. Arch. Neurol. 68, 985–989 (2011). source

      The Animal Models section reports enhanced anxiety, fear, and elevated corticosterone in an RTT mouse model; Medical Issues in Rett syndrome identifies anxiety and scoliosis among clinical concerns (page numbers unavailable). The paper does not link these symptoms to perturbations in lipid homeostasis or discuss sterols as their possible cause. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • Rests on an assumption: Sterols are the precursors of steroid hormones, bile acids and vitamin D.

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

    Premisecitation

    Either increased or decreased amounts of sterols can impair neurological function, demanding a tight regulation of brain sterol synthesis.

    “Either increased or decreased amounts of sterols can impair neurological function, demanding a tight regulation of brain sterol synthesis35.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [35] Ko, M. et al. Cholesterol-mediated neurite outgrowth is differently regulated between cortical and hippocampal neurons. J. Biol. Chem. 280, 42759–42765 (2005). source

      The Results and Discussion (pages not provided) show that both cholesterol loading and depletion reduced neurite outgrowth in cultured cortical neurons, supporting the need for an optimal cholesterol concentration in that setting. The paper does not establish that altered sterol amounts impair neurological function generally or that brain sterol synthesis must be tightly regulated; it says the findings still need confirmation in vivo. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    The only other mouse mutant to show decreased brain cholesterol synthesis is Cyp46a1, which lacks 24SOHC, required for brain cholesterol turnover.

    “The only other mouse mutant to show decreased brain cholesterol synthesis is Cyp46a1, which lacks 24SOHC, required for brain cholesterol turnover44.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [44] Lund, E.G. et al. Knockout of the cholesterol 24-hydroxylase gene in mice reveals a brain-specific mechanism of cholesterol turnover. J. Biol. Chem. 278, 22980–22988 (2003). source

      The Results report that Cyp46a1 knockout mice had about 40% lower brain cholesterol synthesis, and the Discussion identifies cholesterol 24-hydroxylase as responsible for at least 40% of brain cholesterol turnover (pages unavailable). The paper does not establish that this is the only other mouse mutant with reduced brain cholesterol synthesis. It also reports low but measurable brain 24(S)-hydroxycholesterol in the knockout mice, rather than its complete absence. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

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

    Findingown data

    The maximum LOD score for Sum5m1Jus was 2.86.

    “The maximum LOD score for Sum5m1Jus was 2.86”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    At P28, there was a similar trend of increased Cyp46a1 expression in B6.Mecp2tm1.1Jae.

    “with a similar trend in B6.Mecp2tm1.1Jae”
    Quote in the paperSubstantial claim
    • Rests on an assumption: At postnatal day 28, Mecp2/Y mice display mild symptoms.

  • The quote only partly states this claim.

    Findingown data

    Five suppressors that ameliorate symptoms of Mecp2 loss were isolated in a dominant ENU mutagenesis suppressor screen in Mecp2 null mice.

    “Five suppressors that ameliorate symptoms of Mecp2 loss were isolated.”
    • Also stated in: § ENU screen identifies five suppressors of Mecp2 · plain
      “Five lines showed inherited suppressor loci”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sqle expression was reduced by nearly 50% in SqleSum3Jus/+ brains at P70, with no compensatory change in Hmgcr.

    “Sqle expression was reduced by nearly 50% in SqleSum3Jus/+ brains at P70, with no compensatory change in Hmgcr”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Most G1 Mecp2tm1.1Bird/Y animals had mild neurological abnormalities by four weeks, and died or had to be killed by 6-16 weeks of age.

    “Most G1 Mecp2tm1.1Bird/Y animals had mild neurological abnormalities by four weeks, and died or had to be killed by 6–16 weeks of age”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Western blot analysis of E8.0 SqleSum3Jus homozygous embryos shows that the expected 64kDa protein is absent as is a 36kDa presumed degradation product.

    “Western blot analysis of E8.0 SqleSum3Jus homozygous embryos shows that the expected 64kDa protein is absent as is a 36kDa presumed degradation product, consistent with a null mutation”
    Quote in the paperSubstantial claim

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

    Findingown data

    A map location for Sum5m1Jus was not confirmed.

    “a map location was not confirmed”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    B6.Mecp2tm1.1Jae/Y mice showed perturbations in brain lipid metabolism, even though they did not display systemic evidence of high cholesterol.

    “B6.Mecp2tm1.1Jae/Y mice showed perturbations in brain lipid metabolism, even though they did not display systemic evidence of high cholesterol.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Moderate amounts of statin drugs were effective, whereas large doses were detrimental.

    “Notably, moderate amounts of statin drugs were effective, whereas large doses were detrimental”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Expression of Hmgcr and Sqle was unchanged in P28 and significantly higher in P56 129.Mecp2tm1.1Bird/Y livers compared to wild type (p≤.05).

    “Expression of Hmgcr and Sqle was unchanged in P28 and significantly higher in P56 129.Mecp2tm1.1Bird/Y livers compared to wild type (p≤.05; Fig. 4e).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Total serum cholesterol, LDL-cholesterol and triglycerides were not elevated in B6.Mecp2tm1.1Jae/Y mice at P56.

    “but not in B6.Mecp2tm1.1Jae/Y mice at P56”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    129.Mecp2tm1.1Bird/+ females accumulated huge amounts of lipids in the liver, yet showed only mildly elevated serum cholesterol and triglycerides.

    “Further, 129.Mecp2tm1.1Bird/+ females accumulated huge amounts of lipids in the liver, yet showed only mildly elevated serum cholesterol and triglycerides.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Total serum cholesterol, LDL-cholesterol and triglycerides were significantly elevated in 129.Mecp2tm1.1Bird/Y mice (p≤.01) at P56.

    “Consistently, total serum cholesterol, LDL-cholesterol and triglycerides were significantly elevated in 129.Mecp2tm1.1Bird/Y mice (p≤.01)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Cholesterol is a major and essential component of the brain, which must be produced there exclusively via synthesis as cholesterol-rich lipoproteins cannot cross the blood brain barrier.

    “Cholesterol is a major and essential component of the brain, which must be produced there exclusively via synthesis as cholesterol-rich lipoproteins cannot cross the blood brain barrier (BBB)29.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [29] Dietschy, J.M., Turley, S.D. & Spady, D.K. Role of liver in the maintenance of cholesterol and low density lipoprotein homeostasis in different animal species, including humans. J. Lipid Res. 34, 1637–1659 (1993). source

  • Classified as probably not a substantial claim.

    Premisecitation

    Mutations in methyl CpG binding protein 2 (MECP2) cause Rett Syndrome.

    “Mutations in methyl CpG binding protein 2 (MECP2) cause Rett Syndrome, the most severe autism spectrum disorder.”
    • Also stated in: § Abstract · plain
      “Mutations in the X-linked gene, methyl CpG binding protein 2 (MECP2), are the primary cause of RTT1.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Amir, R.E. et al. Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG–binding protein 2. Nat. Genet. 23, 185–188 (1999). source

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

    Premisecitation

    SQLE's enzymatic reaction requires a mitochondrial electron donor to produce 2,3-oxidosqualene, which is cyclized to lanosterol by lanosterol synthase (LSS).

    “SQLE’s enzymatic reaction requires a mitochondrial electron donor to produce 2,3-oxidosqualene, a transient intermediate that is cyclized to lanosterol by lanosterol synthase (LSS)23.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] Shibata, N. et al. Supernatant protein factor, which stimulates the conversion of squalene to lanosterol, is a cytosolic squalene transfer protein and enhances cholesterol biosynthesis. Proc. Natl. Acad. Sci. USA 98, 2244–2249 (2001). source

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

    Premisecitation

    Cholesterol synthesis takes place through complex pathways, all of which use the rate-limiting enzymes HMGCR and SQLE.

    “Cholesterol synthesis takes place through complex pathways, all of which use the rate-limiting enzymes HMGCR and SQLE28.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Nieweg, K., Schaller, H. & Pfrieger, F.W. Marked differences in cholesterol synthesis between neurons and glial cells from postnatal rats. J. Neurochem. 109, 125–134 (2009). source

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

    Premisecitation

    SQLE is expressed in many tissues.

    “SQLE is expressed in many tissues24 and is conserved throughout evolution; the mouse and human proteins are 84% identical at the amino acid level.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] Astruc, M., Tabacik, C., Descomps, B. & de Paulet, A.C. Squalene epoxidase and oxidosqualene lanosterol-cyclase activities in cholesterogenic and non-cholesterogenic tissues. Biochim. Biophys. Acta 487, 204–211 (1977). source

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

    Study design and conductnone given

    Gene expression was normalized to an RpL19 (L19) internal loading control.

    “Gene expression was normalized to an RpL19 (L19) internal loading control”
    Quote in the paperNot a substantial claim

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

    Study design and conductown data

    Equal variances were not assumed because the Mecp2 mutant group typically showed increased variability compared to wild type.

    “equal variances were not assumed, as the Mecp2 mutant group typically showed increased variability compared to wild type.”
    Quote in the paperNot a substantial claim

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

    Study design and conductnone given

    These findings do not comprise a pre-clinical trial.

    “Although these findings do not comprise a pre-clinical trial”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    Variants were removed from consideration if identified in any of 15 other mouse strains, other lines from this study, or other phenotypes, to remove inbred strain polymorphisms and systematic sequencing artifacts.

    “To remove inbred strain polymorphisms as well as systematic sequencing artifacts, variants were removed from consideration if identified in any of 15 other mouse strains (including the parental strains, resequenced alongside the mutants), other lines from this study, or other phenotypes.”
    Quote in the paperSubstantial claim

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

    Interpretationreasoning

    The unchanged total liver cholesterol and phospholipid concentrations reflect the transient nature and rapid packaging of newly synthesized cholesterol into lipoproteins for secretion.

    “reflecting the transient nature and rapid packaging of newly synthesized cholesterol into lipoproteins for secretion”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Desmosterol is the most prevalent intermediate produced by the primary cholesterol synthesis pathway in the adult brain.

    “Desmosterol is the most prevalent intermediate produced by the primary cholesterol synthesis pathway in the adult brain33.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] Pfrieger, F.W. & Ungerer, N. Cholesterol metabolism in neurons and astrocytes. Prog. Lipid Res. 50, 357–371 (2011). source

  • May combine two claims.

    Premisecitation

    Fat accumulation in Mecp2 mutant mice is a sign of perturbed metabolism that can lead to fatty liver disease when hepatic lipid accumulation is followed by an increase in oxidative and metabolic stress.

    “This fat accumulation is a sign of perturbed metabolism that can lead to fatty liver disease (FLD) when hepatic lipid accumulation is followed by an increase in oxidative and metabolic stress50.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [50] Day, C.P. & James, O.F. Steatohepatitis: a tale of two “hits?”. Gastroenterology 114, 842–845 (1998). source

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

    Study design and conductnone given

    Single product amplification was confirmed by disassociation curves and agarose gel electrophoresis.

    “Single product amplification was confirmed by disassociation curves and agarose gel electrophoresis.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Treatment starting at an early age may maintain some level of pathway activity in the brain to increase lifespan and ameliorate motor symptoms in Mecp2 mutant mice.

    “Treatment starting at an early age may therefore maintain some level of pathway activity in the brain to increase lifespan and ameliorate motor symptoms in Mecp2 mutant mice.”
    Quote in the paperSubstantial claim
45 of 45

  • The paper relies on this without support.

    Prior analysis suggested that expression of Hmgcr and Sqle were predictive of the behavior of genes encoding intermediate enzymes in the pathways.

    “Prior analysis suggested that expression of Hmgcr and Sqle were predictive of the behavior of genes encoding intermediate enzymes in the pathways (data not shown).”

  • The paper relies on this without support.

    The long isoform, unlike the short isoform, is consistently translated to protein in mammalian species.

    “which unlike the short isoform, is consistently translated to protein in mammalian species”

  • The paper relies on this without support.

    SQLE is conserved throughout evolution; the mouse and human proteins are 84% identical at the amino acid level.

    “SQLE is expressed in many tissues24 and is conserved throughout evolution; the mouse and human proteins are 84% identical at the amino acid level.”

  • The paper relies on this without support.

    At postnatal day 28, Mecp2/Y mice display mild symptoms.

    “At postnatal day 28 (P28), when Mecp2/Y mice display mild symptoms”

  • The paper relies on this without support.

    By P56, mutant males are severely symptomatic.

    “by P56 when mutant males are severely symptomatic”

  • The paper relies on this without support.

    Two isoforms are annotated in mice.

    “Two isoforms are annotated in mice”

  • The paper relies on this without support.

    Lovastatin is highly lipophilic, increasing the likelihood it will reach the brain.

    “Lovastatin was of particular interest because it is highly lipophilic, increasing the likelihood it will reach the brain”

  • The paper relies on this without support.

    Within a fixed window of time, cholesterol synthesis in the brain is likely to vary among cell types, including neuronal subtypes in various states of differentiation and activity, as well as among non-neuronal cells, including astrocytes, oligodendrocytes and microglia.

    “Within a fixed window of time, cholesterol synthesis in the brain is likely to vary among cell types, including neuronal subtypes in various states of differentiation and activity, as well as among non-neuronal cells, including astrocytes, oligodendrocytes and microglia.”

  • The paper relies on this without support.

    Statins affect pathways upstream of cholesterol synthesis and are indiscriminate of cell type, whereas SQLE’s effect is limited to cholesterol synthesis in a subset of neurons and glial cells.

    “Statins affect pathways upstream of cholesterol synthesis and are indiscriminate of cell type, whereas SQLE’s effect is limited to cholesterol synthesis in a subset of neurons and glial cells.”

  • The paper relies on this without support.

    Lipid homeostasis is controlled by an interplay of multiple organ systems at many levels of feedback.

    “Lipid homeostasis is controlled by an interplay of multiple organ systems at many levels of feedback”

  • The paper relies on this without support.

    Sterols are the precursors of steroid hormones, bile acids and vitamin D.

    “Sterols are the precursors of steroid hormones, bile acids and vitamin D”
11 of 11

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Lovastatin significantly improved systemic lipid profile, ameliorated motor behaviors and increased lifespan of Mecp2-null mice.

    “Lovastatin significantly improved systemic lipid profile, ameliorated motor behaviors and increased lifespan of Mecp2-null mice [77], whereas a second study performed on Mecp2-deficient mice with a different genetic background show no effect of lovastatin [81].”

    From Loss of Mevalonate/Cholesterol Homeostasis in the Brain: A Focus on Autism Spectrum Disorder and Rett Syndrome (2019) · cites this paper as [77]

    The Results section (page unavailable) reports that lovastatin ameliorated motor symptoms in 129.Mecp2-null male mice, measured by rotarod and open-field activity. It attributes lowered cholesterol and increased lifespan specifically to fluvastatin; the copy does not establish those outcomes for lovastatin. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • An earlier publication using gas chromatography and mass spectrometry in Mecp2−/y mice and wildtype controls at 56 and 70 days showed significantly lower brain desmosterol concentrations in the mutants.

    “An earlier publication utilizing this technique in Mecp2−/y mice and their wildtype controls at 56 and 70 days showed significantly lower brain desmosterol concentrations in the mutants.”

    From Suppression of brain cholesterol synthesis in male Mecp2-deficient mice is age dependent and not accompanied by a concurrent change in the rate of fatty acid synthesis (2017) · cites this paper as Buchovecky et al., 2013

    The Results section reports lower brain desmosterol in Mecp2 mutant males at P56 (p=.01) and a further decrease at P70, but gives no significance value for the P70 comparison. The Online Methods section says cholesterol intermediates were measured by tandem mass spectrometry; gas-liquid chromatography was used to measure tissue cholesterol, not desmosterol. No page numbers are available in our copy. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Earlier studies in 56-day-old Jaenisch mice showed that, unlike the brain, other organs including the liver did not manifest a lower rate of cholesterol synthesis.

    “The earlier studies in 56-day-old Jaenisch mice showed that, unlike the brain, other organs including the liver did not manifest a lower rate of cholesterol synthesis (Buchovecky et al., 2013).”

    From Suppression of brain cholesterol synthesis in male Mecp2-deficient mice is age dependent and not accompanied by a concurrent change in the rate of fatty acid synthesis (2017) · cites this paper as Buchovecky et al., 2013

    The Results section (page unavailable) reports decreased cholesterol synthesis in the brain of adult Jaenisch mice, but a modest increase—not a decrease—in their liver at P56. That supports the brain–liver contrast. Our copy does not establish the same result for other organs generally. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • In 70-day-old Mecp2−/y mice (Bird allele) on a 129S6/SvEv background, plasma total cholesterols were about 50% higher than in wildtype controls.

    “In 70-day-old Mecp2−/y mice (Bird allele) on a 129S6/SvEv background, plasma total cholesterols were about 50% higher than in their wildtype controls (Buchovecky et al., 2013).”

    From Suppression of brain cholesterol synthesis in male Mecp2-deficient mice is age dependent and not accompanied by a concurrent change in the rate of fatty acid synthesis (2017) · cites this paper as Buchovecky et al., 2013

    The Results section (‘Mecp2 null males have abnormal cholesterol metabolism’; page not provided) reports significantly elevated total serum cholesterol in 129-background Bird-allele mutant males relative to controls at postnatal day 56. It does not establish the claimed approximately 50% increase at day 70; the Online Methods specify serum-cholesterol assessments at days 28 and 56. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • In subcortical regions of brains from 56-day-old mice, Cyp46a1 mRNA expression was about 40% lower in Mecp2−/y mice than in Mecp2+/y controls, but in 28-day-old mice the converse was found.

    “In a subsequent study using qRT-PCR, the Justice laboratory (Buchovecky et al., 2013) showed that in the subcortical regions (containing the corpus callosum, striatum, thalamus, hypothalamus and hippocampus) of brains from 56-day-old mice, the expression level of mRNA for Cyp46a1 was about 40% lower in the Mecp2−/y mice than in their Mecp2+/y controls but in 28-day-old mice the converse was found.”

    From Suppression of brain cholesterol synthesis in male Mecp2-deficient mice is age dependent and not accompanied by a concurrent change in the rate of fatty acid synthesis (2017) · cites this paper as Buchovecky et al., 2013

    The Results section (‘Mecp2 null males have abnormal cholesterol metabolism’; page unavailable) reports that Cyp46a1 expression was 38% higher than wild type at P28 and was downregulated at P56. The Online Methods confirm that brain analyses used the specified subcortical region and that gene expression was measured by qRT-PCR. Our copy does not give the claimed approximately 40% decrease at P56, so that magnitude remains unsupported. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Self-check results appear here once an independent check has confirmed them.

Cited works that were retracted

Works this paper cites that were later retracted, from the retraction notices publishers deposit. Major when the notice came out before this paper was published.

  • Cites a retracted work: 10.1016/s1097-2765(03)00276-4

    Info

    The cited work was retracted on 2019-03-07 (notice 10.1016/j.molcel.2019.02.022), not before this paper was published (2013-07-28).

    Cited work 10.1016/s1097-2765(03)00276-4 · retracted 2019-03-07 · notice 10.1016/j.molcel.2019.02.022 · this paper published 2013-07-28

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Related

Authors
Buchovecky, C. M., Turley, S. D., Brown, H. M., Kyle, S. M., McDonald, J. G., Liu, B., Pieper, A. A., Huang, W., Katz, D. M., Russell, D. W., Shendure, J., & Justice, M. J.
Affiliations
  • Baylor College of Medicine (US)
  • The University of Texas Southwestern Medical Center (US)
  • University of Washington (US)
  • Case Western Reserve University (US)
Corresponding author
Justice, Monica J
ORCID
Venue
Nature Genetics
Publisher
Springer Science and Business Media LLC
Published
2013-07-28
Volume
45
Issue
9
Pages
1013-1020
ISSN
  • 1061-4036 (ISSN-L)
  • 1546-1718
DOI
10.1038/ng.2714
PMC
PMC3837522
OpenAlex
W2150786121
Cited by
234
References
66
Citations by year
2026: 14 · 2025: 9 · 2024: 15 · 2023: 13 · 2022: 12 · 2021: 28 · 2020: 21 · 2019: 22 · 2018: 13 · 2017: 23 · 2016: 24 · 2015: 13 · 2014: 18 · 2013: 7
FWCI
12.53
Type
journal article
Language
en
Open access
Licence
www.springer.com/tdm (tdm)
Locations
  • Nature Genetics (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion)
  • PubMed Central (submittedVersion)
  • Adelaide Research & Scholarship (AR&S) (University of Adelaide) (submittedVersion)
Funders
  • National Heart, Lung, and Blood Institute (R01 HL-09610, R01HL009610)
  • National Cancer Institute (R01CA115503)
  • National Institute of General Medical Sciences (U54-GM-69338, T32 GM008307, T32 GM08307, U54GM069338)
  • National Institute of Diabetes and Digestive and Kidney Diseases (P30DK079638, 2P30DK079638-05)
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (P30HD 024064, 5P30HD024064-23)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Neurodevelopmental Disorders
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Autism Spectrum Disorder Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genomics and Rare Diseases
Keywords
Rett syndrome, MeCP2, Mecp2-null mice, suppressor screen, squalene epoxidase, cholesterol biosynthesis, cholesterol homeostasis, lipid metabolism, statins, longevity, autism spectrum disorder, N-ethyl-N-nitrosourea mutagenesis
MeSH terms
Animals, Behavior, Animal, Cholesterol, Chromosome Mapping, Disease Models, Animal, Female, Male, Mutation, Rett Syndrome, Mice, Knockout, Codon, Terminator, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Quantitative Trait Loci, Mice, Methyl-CpG-Binding Protein 2

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-27.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-27.

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Statistics and arithmetic are recomputed, not judged.

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