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Cited by 11Genetics and Neurodevelopmental DisordersCholesterol and Lipid MetabolismCancer, Lipids, and Metabolism

Brain Cholesterol Biosynthetic Pathway Is Altered in a Preclinical Model of Fragile X Syndrome

Open access
Parente, Martina, Tonini, Claudia, Buzzelli, Valeria, Carbone, Emilia, Trezza, Viviana, Pallottini, Valentina·2022·International Journal of Molecular Sciences
DOI 10.3390/ijms23063408PMC PMC8955806
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Abstract

Fragile X Syndrome (FXS) is the most frequent form of inherited X-linked pathology, associated with an intellectual and developmental disability, and currently considered the first monogenic cause of autism spectrum disorder (ASD). Low levels of total cholesterol reported in the serum of FXS patients, and evidence that FMRP targets a subset of mRNAs encoding proteins of lipid synthesis and transport suggests that the cholesterol metabolism impairments could be involved in FXS. Thus, the aim of the presented work was to investigate the modulations of the cholesterol biosynthetic pathway and its end-products in a recently developed Fmr1-Δexon 8 rat model of FXS. Here, we show that this experimental model mimics what is found in FXS patients, exhibiting a lower serum cholesterol content, accompanied by a reduction in food intake and body weight compared to WT animals. Moreover, alterations of proteins committed to cholesterol synthesis and uptake have been observed in the amygdala, prefrontal cortex and nucleus accumbens. Interestingly, the end-products show a brain region-dependent modulation in Fmr1-Δexon 8 rats. Overall, our results demonstrate that the cholesterol biosynthetic pathway is altered in some brain regions of this preclinical model of FXS. This finding has relevance for future studies to delve deeper into the involvement of this metabolic process in FXS, and thus its possible role as a therapeutic target.

AI snapshot

Written from the paper’s full text.

TL;DR

In Fmr1-Δexon 8 rats, serum cholesterol was lower than in WT controls, accompanied by reduced food intake and body weight, while brain cholesterol biosynthetic pathway proteins were altered in a region-dependent manner. The model mimics some lipid features reported in FXS patients and suggests MVA pathway involvement in FXS.

Key findings

  • Serum cholesterol decreased in both PND35 and PND90 Fmr1-Δexon 8 rats versus WT; adult Fmr1-Δexon 8 rats weighed about 18% less than WT controls and showed reduced food intake. Liver HMGCR, LDLR, and hepatic cholesterol content were unchanged.
  • In brain, HMGCR and LDLR decreased in the amygdala and nucleus accumbens and increased in the prefrontal cortex at both PND35 and PND90; no changes were observed in cerebellum, hippocampus, or dorsal striatum, meaning 3 of 6 brain regions were affected.
  • At PND90, tissue cholesterol was altered only in the amygdala, where cholesterol accumulated; CYP46A1 and nuclear SREBP2 decreased in the amygdala, while cholesterol content was unchanged in prefrontal cortex and nucleus accumbens.
  • In nucleus accumbens, activated RhoA decreased, consistent with reduced HMGCR; no changes in measured prenylated proteins were observed in the amygdala.

Methods

  • Male Fmr1-Δexon 8 rats, generated by zinc-finger nuclease-induced exon 8 deletion on an outbred Sprague-Dawley background, and WT controls were used at PND35 and PND90; only males were studied, with six animals per experimental group.
  • Serum, liver, and six brain regions (amygdala, cerebellum, prefrontal cortex, hippocampus, nucleus accumbens, dorsal striatum) were collected; food intake was measured over the last 6 days in PND90 rats.
  • Cholesterol was measured with the Cholesterol Quantitation Kit MAK043, and Western blotting assessed HMGCR, LDLR, CYP46A1, nuclear SREBP2, RhoA, and HRas; data are mean ± SD and were analyzed by unpaired Student’s t-tests.

Limitations

  • The paper states that other metabolic mechanisms contributing to plasma cholesterol imbalance cannot be excluded, that potential differences between hemizygous males and heterozygous females were not considered, and that further studies are needed to clarify region-specific modulations and specific cell types; other lipids may also be modulated.
  • Evident from the text: only male rats were used, so sex-dependent effects could not be evaluated; the sample size was six per group; and the findings are from a preclinical rat model rather than human FXS patients.

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

Integrity signals

Registry

Crossref · 10.3390/ijms23063408

Cites

61 of 61 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

17 of 36 cited sources checked · 10 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Statistically significant lower levels of total cholesterol and HDL-cholesterol have been observed in the serum of FXS patients compared to the normal population.

    “statistically significant lower levels of total cholesterol and HDL-cholesterol have been observed in the serum of FXS patients if compared to the normal population [26,27].”
    • Also stated in: § Abstract · plain
      “Low levels of total cholesterol reported in the serum of FXS patients”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [26] Lisik, 2016, Low Levels of HDL in Fragile X Syndrome Patients, Lipids source

      The Results report significantly lower HDL-C in FXS patients than in age-matched controls. Total cholesterol was lower on average, but the difference was not statistically significant (Table 2, p = 0.09). The study compared patients with controls, not with population-wide normative data; page numbers were not provided in our copy. (LLM, conf=0.93)

      Experimental — accuracy not yet measured
    • cites [27] Çaku, A., Seidah, N.G., Lortie, A., Gagné, N., Perron, P., Dubé, J., and Corbin, F. (2017). New Insights of Altered Lipid Profile in Fragile X Syndrome. PLoS ONE, 12. source

      The Results (Lipid profile) report significantly lower total cholesterol (p<0.001) and HDL-C (p=0.002) in male FXS participants than in the age-adjusted normal male population. The analysis was not pursued for female participants, so the unqualified claim about FXS patients is broader than the finding reported here. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Premisecitation

    FMRP targets a subset of mRNAs encoding proteins critically involved in lipid synthesis and transport.

    “it was found that FMRP targets a subset of mRNA encoding proteins critically involved in lipid synthesis and transport [6].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Kalinowska, M., Castillo, C., and Francesconi, A. (2015). Quantitative Profiling of Brain Lipid Raft Proteome in a Mouse Model of Fragile X Syndrome. PLoS ONE, 10. source
  • Premisecitation

    Pharmacological inhibition of the MVA pathway corrects excessive hippocampal protein synthesis and susceptibility to audiogenic seizures in FXS mice.

    “it has been demonstrated that the pharmacological inhibition of the MVA pathway corrects the excessive hippocampal protein synthesis and susceptibility to audiogenic seizures displayed by FXS mice, suggesting a potential role of the cholesterol biosynthetic pathway in this pathology [25].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [25] Muscas, 2019, Lovastatin, Not Simvastatin, Corrects Core Phenotypes in the Fragile X Mouse Model, eNeuro source

      The Results (no page available) show that lovastatin normalizes excessive hippocampal protein synthesis and reduces audiogenic seizure incidence in Fmr1-/y mice. But the same sections report that simvastatin does not correct either phenotype, so the source does not support the unqualified claim that pharmacological inhibition of the mevalonate pathway does so. The Discussion proposes an effect through ERK1/2 signaling rather than establishing inhibition of cholesterol biosynthesis as the corrective mechanism. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Interpretationown data

    The Fmr1-Δexon 8 rat model mimics the reduced plasma cholesterol content observed in FXS patients.

    “Our study demonstrates that the Fmr1-Δexon 8 preclinical model mimics the reduced plasma cholesterol content observed in FXS patients [26,27].”
    • Also stated in: § 3. Discussion · boosted
      “The cholesterol plasma alterations observable in patients [26,27] are excellently mimicked by Fmr1-Δexon 8 rats”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [26] Lisik, 2016, Low Levels of HDL in Fragile X Syndrome Patients, Lipids source

      The Results report significantly lower serum HDL-C in FXS patients, but total cholesterol did not differ statistically from controls. The Discussion likewise says total cholesterol was lower only as a nonsignificant trend. This supports reduced HDL-C, not an established reduction in overall cholesterol content; the rat-model finding is the citing authors’ own result. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites [27] Çaku, A., Seidah, N.G., Lortie, A., Gagné, N., Perron, P., Dubé, J., and Corbin, F. (2017). New Insights of Altered Lipid Profile in Fragile X Syndrome. PLoS ONE, 12. source
  • Findingown data

    In the cerebellum, hippocampus and dorsal striatum, no changes in HMGCR and LDLR were observed in Fmr1-Δexon 8 animals.

    “in the cerebellum, hippocampus and dorsal striatum, no changes were observed in Fmr1-Δexon 8 animals (Supplementary Figure S1).”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 23
  • May combine two claims. 11

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

    Premisecitation

    RhoA activity has been related to developmental disabilities, such as mental retardation.

    “Therefore, it is not surprising that RhoA activity has been related to developmental disabilities, such as mental retardation [55].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [55] Linseman, 2008, Diverse Roles of Rho Family GTPases in Neuronal Development, Survival, and Death, Front. Biosci. source

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

    Premisecitation

    HMGCR inhibition, and in turn the reduction in RhoA activation, are deeply involved in neurite outgrowth.

    “For instance, we have previously demonstrated that HMGCR inhibition, and in turn the reduction in RhoA activation, are deeply involved in neurite outgrowth [10].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [10] Cartocci, 2016, Modulation of the Isoprenoid/Cholesterol Biosynthetic Pathway During Neuronal Differentiation In Vitro: MVA Pathway In Neuronal Differentiation, J. Cell. Biochem. source

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

    Premisecitation

    80% of the cholesterol present in the mammal body is endogenously synthesized, mainly in the liver.

    “although 80% of the cholesterol present in the mammal body is endogenously synthesized, mainly in the liver [42].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [42] Martini, 2007, Cholesterol: From Feeding to Gene Regulation, Genes Nutr. source

      The Introduction (page unavailable) says cholesterol is both synthesized by cells and obtained from food. “From enterocytes to limph and liver” (page unavailable) says de novo synthesis occurs mainly in the liver when cholesterol supply is low. Neither passage supports the claim that 80% of cholesterol in a mammal’s body is endogenously synthesized. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

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

    Premisecitation

    The MVA pathway is altered in a region-, sex-, and age-dependent manner in the brain of a preclinical model of ASD, such as rats prenatally exposed to valproate.

    “the MVA pathway results altered in dependence of the region, the sex and the age in the brain of a preclinical model of ASD, such as rats prenatally exposed to valproate [22,23,24].”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [22] Cartocci, 2018, Altered Brain Cholesterol/Isoprenoid Metabolism in a Rat Model of Autism Spectrum Disorders, Neuroscience source
    • cites [23] Cartocci, 2017, Can Cholesterol Metabolism Modulation Affect Brain Function and Behavior?, J. Cell. Physiol. source
    • cites [24] Segatto, M., Tonini, C., Pfrieger, F.W., Trezza, V., and Pallottini, V. (2019). Loss of Mevalonate/Cholesterol Homeostasis in the Brain: A Focus on Autism Spectrum Disorder and Rett Syndrome. Int. J. Mol. Sci., 20. source

  • May combine two claims.

    Premisecitation

    The deletion of exon 8 in the Fmr1-Δexon 8 rat is sufficient to cause FXS-like traits, such as deficits in sustained visuospatial attention, altered patterns of social interaction, cognitive impairment, and abnormal synaptic plasticity.

    “Such deletion is sufficient to cause FXS-like traits, such as deficits in sustained visuospatial attention [34], altered patterns of social interaction, and cognitive impairment [28], together with abnormal synaptic plasticity [32,35,36].”
    Quote in the paperSubstantial claim3 of 5 sources checked
    • cites [34] Golden, 2019, Deletion of the KH1 Domain of Fmr1 Leads to Transcriptional Alterations and Attentional Deficits in Rats, Cereb. Cortex source
    • cites [28] Schiavi, 2020, Perinatal Supplementation with Omega-3 Fatty Acids Corrects the Aberrant Social and Cognitive Traits Observed in a Genetic Model of Autism Based on FMR1 Deletion in Rats, Nutr. Neurosci. source
    • cites [32] Hamilton, 2014, Fmr1 and Nlgn3 Knockout Rats: Novel Tools for Investigating Autism Spectrum Disorders, Behav. Neurosci. source
    • cites [35] Till, 2015, Conserved Hippocampal Cellular Pathophysiology but Distinct Behavioural Deficits in a New Rat Model of FXS, Hum. Mol. Genet. source
    • cites [36] Tian, 2017, Loss of FMRP Impaired Hippocampal Long-Term Plasticity and Spatial Learning in Rats, Front. Mol. Neurosci. source

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

    Study design and conductreasoning

    The study did not consider potential differences between hemizygous males and heterozygous females.

    “Moreover, we did not consider the potential differences between hemizygous males and heterozygous females; this is a very interesting point since cholesterol metabolism displays sex-dependent differences [24], and this issue deserves further evaluation.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [24] Segatto, M., Tonini, C., Pfrieger, F.W., Trezza, V., and Pallottini, V. (2019). Loss of Mevalonate/Cholesterol Homeostasis in the Brain: A Focus on Autism Spectrum Disorder and Rett Syndrome. Int. J. Mol. Sci., 20. source

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

    Premisecitation

    Cholesterol metabolism displays sex-dependent differences.

    “since cholesterol metabolism displays sex-dependent differences [24]”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [24] Segatto, M., Tonini, C., Pfrieger, F.W., Trezza, V., and Pallottini, V. (2019). Loss of Mevalonate/Cholesterol Homeostasis in the Brain: A Focus on Autism Spectrum Disorder and Rett Syndrome. Int. J. Mol. Sci., 20. source

  • May combine two claims.

    Premisecitation

    The Fmr1-Δexon 8 rat model is not a null KO of Fmr1; the induced mutation results in a gene product with a loss of exon 8, which encodes the KH1 domain responsible for RNA-binding.

    “Recently, it has been shown that this model is not a null KO of Fmr1, but instead, the induced mutation results in a gene product with a loss of exon 8, which encodes a domain responsible for RNA-binding, named KH1 domain [33].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [33] Kenkel, 2016, Functional Magnetic Resonance Imaging in Awake Transgenic Fragile X Rats: Evidence of Dysregulation in Reward Processing in the Mesolimbic/Habenular Neural Circuit, Transl. Psychiatry source

      The Introduction says that the fmr1-tm1Cgr mouse is not a complete molecular null, but it does not make that statement about the rat model. Searches for exon 8, KH1, and a non-null Fmr1 rat gene product found no passage addressing the claimed mutation or its RNA-binding domain. (LLM, conf=0.75)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    Small GTPases need post-translational modification to target them to cellular membranes and be active.

    “All these small GTPase need post-translational modification to target them to cellular membranes and be active [16,17].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [16] Reddy, 2020, Regulation of Small GTPase Prenylation in the Nervous System, Mol. Neurobiol. source
    • cites [17] Garstka, 2021, Targeting Small GTPases and Their Prenylation in Diabetes Mellitus, J. Med. Chem. source

      The Overview of Superfamily of Small GTPases and Enzymes within the Mevalonate Pathway (page unavailable) says small GTPases usually carry a post-translationally attached prenyl tail and explains that masking this tail prevents Rho and Rab from associating with target membranes. It does not establish that all small GTPases require modification to become active; it describes activation as the exchange of GDP for GTP. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data

    In the nucleus accumbens of Fmr1-Δexon 8 rats, the reduction in HMGCR levels is accompanied by a decrease in RhoA activation, whereas no cholesterol alteration was detected in the tissue.

    “Concerning the nucleus accumbens, the reduction in HMGCR levels is accompanied by a decrease in RhoA activation, whereas no cholesterol alteration was detected in the tissue.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    LDLR is committed to cholesterol uptake.

    “the low-density lipoprotein receptor (LDLR) which are committed to cholesterol synthesis and uptake, respectively [19].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19] Espenshade, 2007, Regulation of Sterol Synthesis in Eukaryotes, Annu. Rev. Genet. source

  • Classified as probably not a substantial claim.

    Premisecitation

    Farnesyl and geranylgeranyl are covalently bound to small GTPases, inducing their membrane translocation and activation.

    “Additional end-products of the cholesterol biosynthetic pathway are represented by prenyls, farnesyl and geranylgeranyl, which are covalently bound to small GTPase inducing their membrane translocation and activation [41].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [41] Zhang, 2021, Key Enzymes for the Mevalonate Pathway in the Cardiovascular System, J. Cardiovasc. Pharmacol. source

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

    Premisecitation

    Modulation of CYP46A1 has been indirectly demonstrated in autistic children, who showed higher plasma 24 HC levels, which progressively decreased with age.

    “Interestingly, modulation of CYP46A1 has been indirectly demonstrated in autistic children, who showed higher plasma 24 HC levels, which progressively decreased with age [49].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [49] Grayaa, 2018, Plasma Oxysterol Profiling in Children Reveals 24-Hydroxycholesterol as a Potential Marker for Autism Spectrum Disorders, Biochimie source

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

    Premisecitation

    The rate-limiting enzyme of the MVA pathway is HMGCR.

    “The MVA pathway consists of a long sequence of enzymatic steps whose rate-limiting enzyme is the 3-Hydroxy 3-methylglutaryl coenzyme A reductase (HMGCR) [19].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19] Espenshade, 2007, Regulation of Sterol Synthesis in Eukaryotes, Annu. Rev. Genet. source

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

    Study design and conductnone given

    The experiments were performed in agreement with the ARRIVE guidelines, the guidelines of the Italian Ministry of Health (D.L. 26/14), and the European Community Directive 2010/63/EU.

    “The experiments were performed in agreement with the ARRIVE (Animals in Research: Reporting In Vivo Experiments) guidelines, the guidelines of the Italian Ministry of Health (D.L. 26/14), and the European Community Directive 2010/63/EU.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites ARRIVE

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

    • cites D.L. 26/14

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

    • cites 2010/63/EU

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

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Intensities of proteins of interest were normalized to intensities of respective housekeeping proteins.

    “Intensities of proteins of interest were normalized to intensities of respective housekeeping proteins.”
    Quote in the paperSubstantial claim

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

    Study design and conductreasoning

    Different housekeeping proteins were used depending on the molecular weight of the analyzed protein, in order to avoid confounding signals when detecting the immunoreactivity.

    “Different housekeeping proteins were used depending on the molecular weight of the analyzed protein, in order to avoid confounding signals when detecting the immunoreactivity.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    In the amygdala of Fmr1-Δexon 8 rats, the cholesterol biosynthetic pathway alteration is driven by the unbalanced rate of cholesterol degradation despite a direct effect on HMGCR.

    “in this area, it seems that cholesterol biosynthetic pathway alteration in Fmr1-Δexon 8 rats is driven by the unbalanced rate of cholesterol degradation despite a direct effect on HMGCR.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    Cholesterol metabolism is altered in numerous neurological pathologies, including ASD.

    “It is widely supported that cholesterol metabolism is altered in numerous neurological pathologies, including ASD [22].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] Cartocci, 2018, Altered Brain Cholesterol/Isoprenoid Metabolism in a Rat Model of Autism Spectrum Disorders, Neuroscience source

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

    Study design and conductnone given

    Caveolin 1 was chosen as a loading control in experiments evaluating proteins in isolated membrane fractions.

    “Finally, caveolin 1 (Santa Cruz Biotechnology dilution 1:1000) was chosen as a loading control in experiments evaluating proteins in isolated membrane fractions.”
    Quote in the paperNot a substantial claim

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

    Study design and conductown data

    Purity control of the obtained membrane fraction was performed by checking the Western blot tubulin content, a purely cytosolic protein.

    “Purity control of the obtained membrane fraction was performed by checking the Western blot tubulin content, a purely cytosolic protein (Supplementary Figure S2).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Supplementary Figure S2

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

    • Rests on an assumption: Tubulin is a purely cytosolic protein.

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

    Interpretationreasoning

    Alterations in HMGCR and LDLR levels change cholesterol synthesis and uptake rate, which may be followed by changes in tissue cholesterol content.

    “Reasonably, alterations in HMGCR and LDLR levels change cholesterol synthesis and uptake rate, which may be followed by changes in tissue cholesterol content.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning

    All cholesterol present in the brain is synthesized in situ, and its content and metabolism do not depend on either hepatic production or diet intake.

    “Consequently, all the cholesterol present in the brain is synthesized in situ, and its content and metabolism do not depend on either hepatic production or diet intake.”
    Quote in the paperSubstantial claim

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

    Study design and conductnone given

    All samples were run in duplicate.

    “All samples were run in duplicate.”
    Quote in the paperNot a substantial claim

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

    Study design and conductnone given

    Antibodies against tubulin or vinculin were chosen as a loading control.

    “Antibodies against tubulin or vinculin (Sigma-Aldrich, Milan, Italy, dilution 1:10,000) were chosen as a loading control.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    CYP46A1 plays a major role in cholesterol homeostasis in the brain by catalyzing the hydroxylation at C-24 of the cholesterol side chain, triggering cholesterol diffusion out of neurons and its further degradation in the liver.

    “CYP46A1 plays a major role in cholesterol homeostasis in the brain since it catalyzes the hydroxylation at C-24 of the cholesterol side chain, thus triggering cholesterol diffusion out of neurons and its further degradation in the liver [40].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [40] Mast, 2008, Crystal Structures of Substrate-Bound and Substrate-Free Cytochrome P450 46A1, the Principal Cholesterol Hydroxylase in the Brain, Proc. Natl. Acad. Sci. USA source

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

    Study design and conductnone given

    The study received Italian Ministry of Health authorization 608/2015-PR.

    “Italian Ministry of Health authorization 608/2015-PR.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    RhoA integrates molecular signals to organize sophisticated and coordinated variations in gene expression and actin cytoskeleton, crucial processes for neurite outgrowth and synaptic connectivity.

    “It integrates molecular signals to organize sophisticated and coordinated variations in gene expression and actin cytoskeleton, crucial processes for the neurite outgrowth and synaptic connectivity [53,54].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [53] Lingor, 2007, Inhibition of Rho Kinase (ROCK) Increases Neurite Outgrowth on Chondroitin Sulphate Proteoglycan in Vitro and Axonal Regeneration in the Adult Optic Nerve in Vivo, J. Neurochem. source
    • cites [54] Gopalakrishnan, 2008, Role of Rho Kinase Pathway in Chondroitin Sulfate Proteoglycan-Mediated Inhibition of Neurite Outgrowth in PC12 Cells, J. Neurosci. Res. source
28 of 28

  • The paper relies on this without support.

    Data focused on the putative alteration of the MVA pathway in FXS are lacking.

    “but data focused on the putative alteration of this complex physiological process are lacking.”

  • The paper relies on this without support.

    Fragile X syndrome is an X-linked disease.

    “since FXS is an X-linked disease, thus females were discarded.”

  • The paper relies on this without support.

    Tubulin is a purely cytosolic protein.

    “a purely cytosolic protein (Supplementary Figure S2).”
3 of 3

Self-check

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

Each contradiction between two passages listed here was confirmed by an independent check.

  • Adult prefrontal LDLR is described as both higher and similar to WT

    Minor

    The results state that prefrontal LDLR is higher in mutant rats at both ages, but the discussion describes its level in adults as similar to adult WT controls.

  • Exon-8 mutant is described as both producing and lacking a protein

    Minor

    The introduction says the mutation produces a gene product missing exon 8, whereas the methods say it causes absence of the protein product. These are incompatible descriptions of the model used in the study.

2 of 2

Cites

Flagged first, then by citations

1 of the 62 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

Related

Authors
Parente, M., Tonini, C., Buzzelli, V., Carbone, E., Trezza, V., & Pallottini, V.
Affiliations
Roma Tre University (IT)
Corresponding author
Pallottini, Valentina
ORCID
Venue
International Journal of Molecular Sciences
Publisher
MDPI AG
Published
2022-03-21
Volume
23
Issue
6
Pages
3408
ISSN
1422-0067 (ISSN-L)
DOI
10.3390/ijms23063408
PMC
PMC8955806
OpenAlex
W4220960290
Cited by
11
References
62
Citations by year
2025: 2 · 2024: 3 · 2023: 6
FWCI
1.48
Type
journal article
Language
en
Open access
Licence
Locations
  • International Journal of Molecular Sciences (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • PubMed Central (submittedVersion, cc-by)
  • Iris (Roma Tre University) (submittedVersion, other-oa)
Funders
  • Ministry of Education, Universities and Research (2017SXEXT5)
  • Jerome Lejeune Foundation Research (1674)
  • Miur (ARTICOLO 1, COMMI 314-337 LEGGE 232/2016)
  • Together Strong NPC-Foundation (2/2020)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Neurodevelopmental Disorders
  • Health Sciences › Medicine › Surgery › Cholesterol and Lipid Metabolism
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Cancer, Lipids, and Metabolism
Keywords
fragile X syndrome, cholesterol biosynthesis, FMRP, serum cholesterol, brain cholesterol metabolism, lipogenesis, amygdala, prefrontal cortex, nucleus accumbens, dietary intake, body weight, autism spectrum disorder, intellectual disability
MeSH terms
Autism Spectrum Disorder, Animals, Brain, Cholesterol, Fragile X Syndrome, Rats, Fragile X Messenger Ribonucleoprotein 1, Fragile X Mental Retardation Protein, Biosynthetic Pathways

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