Precholesterol Sterols Accumulate in Lipid Rafts of Patients with Smith-Lemli-Opitz Syndrome and X-Linked Dominant Chondrodysplasia Punctata

Systemic fetal dysmorphogenesis in disorders of postsqualene cholesterol biosynthesis is thought to be caused by disruption of Hedgehog signaling. Because precholesterol sterols such as 7-dehydrocholesterol and lathosterol can replace cholesterol in the activation of Hedgehog proteins, it is currently believed that cholesterol deficiency-related Hedgehog signaling block occurs further downstream, probably at the level of Smoothened. Experimentally, such a block in Hedgehog signaling occurs at sterol levels of <40 μg/mg protein. Recently, we studied autopsy material from 2 infants with fatal cholesterol biosynthetic disorders (Smith-Lemli-Opitz syndrome and X-linked dominant chondrodysplasia punctata) in which the hepatic cholesterol levels were far greater. In this study, we demonstrate abnormal accumulation of sterol precursors of cholesterol in membrane lipid rafts (detergent resistance membranes) prepared from liver tissues of these 2 infants: 8-dehydrocholesterol and 7-dehydrocholesterol in lipid rafts of the infant with Smith-Lemli-Opitz syndrome and cholest-8(9)-ene-3β-ol in lipid rafts of the infant with X-linked dominant chondrodysplasia punctata. We suggest that such alterations in the lipid raft sterol environment may affect the biology of cells and the development of fetuses with cholesterol biosynthetic disorders.

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Pre-cholesterol sterols accumulate in lipid rafts of patients with Smith-Lemli-Opitz syndrome and X-linked dominant chondrodysplasia punctata

Pediatric and Developmental Pathology ◽

10.2350/06-10-0179 ◽

2006 ◽

Vol preprint (2007) ◽

pp. 1

Author(s):

Dinesh Rakheja ◽

Richard Boriack

Keyword(s):

Lipid Rafts ◽

Chondrodysplasia Punctata ◽

Opitz Syndrome

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Phosphatidylcholine: Greasing the Cholesterol Transport Machinery

Lipid Insights ◽

10.4137/lpi.s31746 ◽

2015 ◽

Vol 8s1 ◽

pp. LPI.S31746 ◽

Cited By ~ 5

Author(s):

Thomas A. Lagace

Keyword(s):

Mammalian Cells ◽

Cholesterol Metabolism ◽

Membrane Lipids ◽

Cholesterol Biosynthesis ◽

Feedback Regulation ◽

Membrane Lipid ◽

Plasma Lipoproteins ◽

Cholesterol Trafficking ◽

Negative Feedback Regulation ◽

Cholesterol Levels

Negative feedback regulation of cholesterol metabolism in mammalian cells ensures a proper balance of cholesterol with other membrane lipids, principal among these being the major phospholipid phosphatidylcholine (PC). Processes such as cholesterol biosynthesis and efflux, cholesteryl ester storage in lipid droplets, and uptake of plasma lipoproteins are tuned to the cholesterol/PC ratio. Cholesterol-loaded macrophages in atherosclerotic lesions display increased PC biosynthesis that buffers against elevated cholesterol levels and may also facilitate cholesterol trafficking to enhance cholesterol sensing and efflux. These same mechanisms could play a generic role in homeostatic responses to acute changes in membrane free cholesterol levels. Here, I discuss the established and emerging roles of PC metabolism in promoting intracellular cholesterol trafficking and membrane lipid homeostasis.

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Sterol profiles in plasma and erythrocyte membranes in patients with Smith-Lemli-Opitz syndrome: a six-year experience

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm.2011.689 ◽

2011 ◽

Vol 49 (12) ◽

Cited By ~ 13

Author(s):

Gaetano Corso ◽

Monica Gelzo ◽

Rosalba Barone ◽

Stefano Clericuzio ◽

Pierluigi Pianese ◽

...

Keyword(s):

Storage Time ◽

Cholesterol Biosynthesis ◽

Erythrocyte Membranes ◽

Gas Chromatography Mass Spectrometry ◽

Chondrodysplasia Punctata ◽

Inborn Errors ◽

Cholesterol Ratio ◽

Negative Linear Correlation ◽

Opitz Syndrome

AbstractThis study reports our experience over the last six years in the diagnosis of Smith-Lemli-Opitz syndrome and other inborn errors of cholesterol biosynthesis.Gas chromatography/mass spectrometry was used to obtain sterol profiles in plasma and erythrocyte membranes of suspected patients.Plasma sterol reference values calculated in unaffected subjects (n=276) were in agreement with those previously reported. Among patients investigated from 2005 to 2010, we report 16 patients affected by Smith-Lemli-Opitz syndrome, three of whom represent new cases and 13 of whom were follow-up patients. In this period we also identified a new case of chondrodysplasia punctata 2 X-linked. The estimated incidence obtained for Smith-Lemli-Opitz syndrome was 1:93 suspected patients (1.08%). We also studied the effect of storage on the dehydrocholesterols/cholesterol ratio in plasma and erythrocyte membranes of patients affected by Smith-Lemli-Opitz syndrome stored at –20°C for up to 22 and 20 months, respectively. A significant negative linear correlation between storage time and the dehydrocholesterols/cholesterol ratio was identified in both plasma and erythrocyte membranes. The decrease in the dehydrocholesterols/cholesterol ratio in erythrocyte membranes was at least two-fold higher than in plasma.The results of this study may be helpful for diagnosis and interpretation of data in patients with findings suggestive of a cholesterol biosynthesis defect.

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ApoE4-carrying Human Astrocytes Oversupply Cholesterol into Neurons and Promote Aβ Generation

10.21203/rs.3.rs-122857/v1 ◽

2020 ◽

Author(s):

Se-In Lee ◽

Woojin Jeong ◽

Sukhee Cho ◽

Hyein Lee ◽

Yonghee Jang ◽

...

Keyword(s):

Lipid Rafts ◽

Late Onset ◽

Culture Media ◽

Amyloid Β ◽

Membrane Lipid ◽

Conditioned Media ◽

Cholesterol Levels ◽

Human Neurons ◽

Aβ Generation ◽

Aβ Production

Abstract Background: The onset of Alzheimer’s disease (AD) typically occurs later in life. Recent genetic analysis of patients and unaffected individuals revealed multiple genetic variants associated with late-onset AD. One of the strongest genetic risk factors for AD is 𝜀4 allele of APOE encoding apolipoprotein (ApoE), which is predominantly expressed in astrocytes. The role and mechanism of ApoE in initiating AD-associated pathologies, including amyloid-β (Aβ) accumulation and neurodegeneration in neurons, remains to be elucidated.Methods: Human induced pluripotent stem cells (hiPSCs) from healthy individuals and isogenic cells in which the ApoE 𝜀3 allele was replaced with an 𝜀4 allele were selected to generate human neurons and astrocytes. To investigate the effect of astrocytic ApoE4 on neuronal Aβ production, iPSC-derived neurons carrying the ApoE 𝜀3 allele were cultured in conditioned media from healthy iPSC-derived astrocytes (ApoE3/E4 heterozygote) for five weeks. Then, the media were replaced with either ApoE3 or ApoE4 astrocyte conditioned media (ACM), cultured for four days, and neuronal amyloid precursor protein (APP) expression and Aβ production were measured. To determine potential mechanisms for upregulation of APP in neurons by ApoE4 ACM, changes in plasma membrane lipid rafts were investigated by staining for cholera toxin B. Methyl-b-cyclodextrin (MβCD) was applied to deplete cholesterol in ApoE4 ACM.Results: Secretory factors in conditioned media from hiPSC-derived astrocytes carrying APOE4 significantly increased the levels of APP and Aβ secretion in hiPSC-derived neurons. Increasing cholesterol levels in culture media mimicked the effects of ApoE4 ACM by inducing the formation of lipid rafts that potentially provide a physical platform for APP localization on the membrane. We further found that reducing cholesterol levels in ApoE4 ACM with MβCD abolished its effects on neuronal lipid raft expansion and Aβ generation.Conclusions: Our study suggests that ApoE4 astrocytes contribute to amyloidosis by the expansion of lipid rafts and facilitate neuronal Ab production through oversupply of cholesterol.

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Smith-Lemli-Opitz syndrome: clinical and biochemical correlates

Journal of Pediatric Endocrinology and Metabolism ◽

10.1515/jpem-2017-0501 ◽

2018 ◽

Vol 31 (4) ◽

pp. 451-459 ◽

Cited By ~ 7

Author(s):

Sarah E. Donoghue ◽

James J. Pitt ◽

Avihu Boneh ◽

Susan M. White

Keyword(s):

Novel Mutation ◽

Cholesterol Biosynthesis ◽

Autosomal Recessive Disorder ◽

Branchial Arch ◽

Term Outcome ◽

Long Term Outcome ◽

Cholesterol Levels ◽

Midline Defects ◽

Opitz Syndrome

AbstractBackground:Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder caused by mutations in theDHCR7gene that result in reduced cholesterol biosynthesis. The aim of the study was to examine the biochemical and clinical features of SLOS in the context of the emerging evidence of the importance of cholesterol in morphogenesis and steroidogenesis.Methods:We retrospectively reviewed the records of 18 patients (including four fetuses) with confirmed SLOS and documented their clinical and biochemical features.Results:Seven patients had branchial arch abnormalities, including micrognathia, immune dysfunction and hypocalcemia. Thymic abnormalities were found in three fetuses. All four patients with a cholesterol level of ≤0.35 mmol/L died. They all had electrolyte abnormalities (hyperkalemia, hyponatremia, hypocalcemia), necrotizing enterocolitis, sepsis-like episodes and midline defects including the branchial and cardiac defects. Patients with cholesterol levels ≥1.7 mmol/L had milder features and were diagnosed at 9 months to 25 years of age. All 10 patients had intellectual disability. One patient was found to have a novel mutation, c.1220A>G (p.Asn407Ser).Conclusions:We suggest that screening for adrenal insufficiency and for hypoparathyroidism, hypothyroidism and immunodeficiency, should be done routinely in infants diagnosed early with SLOS. Early diagnosis and intervention to correct these biochemical consequences may decrease mortality and improve long-term outcome in these patients.

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Faculty Opinions recommendation of Contamination of nuclear fractions with plasma membrane lipid rafts.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1072051.525027 ◽

2007 ◽

Author(s):

Michael Roth

Keyword(s):

Plasma Membrane ◽

Lipid Rafts ◽

Membrane Lipid ◽

Plasma Membrane Lipid

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Abnormal brain cholesterol homeostasis in Alzheimer’s disease—a targeted metabolomic and transcriptomic study

npj Aging and Mechanisms of Disease ◽

10.1038/s41514-021-00064-9 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Vijay R. Varma ◽

H. Büşra Lüleci ◽

Anup M. Oommen ◽

Sudhir Varma ◽

Chad T. Blackshear ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Brain Tissue ◽

Cholesterol Metabolism ◽

Cholesterol Biosynthesis ◽

Cholesterol Homeostasis ◽

Transcriptomic Data ◽

Brain Cholesterol ◽

Cholesterol Levels

AbstractThe role of brain cholesterol metabolism in Alzheimer’s disease (AD) remains unclear. Peripheral and brain cholesterol levels are largely independent due to the impermeability of the blood brain barrier (BBB), highlighting the importance of studying the role of brain cholesterol homeostasis in AD. We first tested whether metabolite markers of brain cholesterol biosynthesis and catabolism were altered in AD and associated with AD pathology using linear mixed-effects models in two brain autopsy samples from the Baltimore Longitudinal Study of Aging (BLSA) and the Religious Orders Study (ROS). We next tested whether genetic regulators of brain cholesterol biosynthesis and catabolism were altered in AD using the ANOVA test in publicly available brain tissue transcriptomic datasets. Finally, using regional brain transcriptomic data, we performed genome-scale metabolic network modeling to assess alterations in cholesterol biosynthesis and catabolism reactions in AD. We show that AD is associated with pervasive abnormalities in cholesterol biosynthesis and catabolism. Using transcriptomic data from Parkinson’s disease (PD) brain tissue samples, we found that gene expression alterations identified in AD were not observed in PD, suggesting that these changes may be specific to AD. Our results suggest that reduced de novo cholesterol biosynthesis may occur in response to impaired enzymatic cholesterol catabolism and efflux to maintain brain cholesterol levels in AD. This is accompanied by the accumulation of nonenzymatically generated cytotoxic oxysterols. Our results set the stage for experimental studies to address whether abnormalities in cholesterol metabolism are plausible therapeutic targets in AD.

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Palmitic acid promotes resistin-induced insulin resistance and inflammation in SH-SY5Y human neuroblastoma

Scientific Reports ◽

10.1038/s41598-021-85018-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hamza Amine ◽

Yacir Benomar ◽

Mohammed Taouis

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Palmitic Acid ◽

Lipid Rafts ◽

Acid Treatment ◽

Protective Action ◽

Saturated Fatty Acids ◽

Membrane Lipid ◽

Human Neuroblastoma ◽

Peripheral Tissues

AbstractSaturated fatty acids such as palmitic acid promote inflammation and insulin resistance in peripheral tissues, contrasting with the protective action of polyunsaturated fatty acids such docosahexaenoic acid. Palmitic acid effects have been in part attributed to its potential action through Toll-like receptor 4. Beside, resistin, an adipokine, also promotes inflammation and insulin resistance via TLR4. In the brain, palmitic acid and resistin trigger neuroinflammation and insulin resistance, but their link at the neuronal level is unknown. Using human SH-SY5Yneuroblastoma cell line we show that palmitic acid treatment impaired insulin-dependent Akt and Erk phosphorylation whereas DHA preserved insulin action. Palmitic acid up-regulated TLR4 as well as pro-inflammatory cytokines IL6 and TNFα contrasting with DHA effect. Similarly to palmitic acid, resistin treatment induced the up-regulation of IL6 and TNFα as well as NFκB activation. Importantly, palmitic acid potentiated the resistin-dependent NFkB activation whereas DHA abolished it. The recruitment of TLR4 to membrane lipid rafts was increased by palmitic acid treatment; this is concomitant with the augmentation of resistin-induced TLR4/MYD88/TIRAP complex formation mandatory for TLR4 signaling. In conclusion, palmitic acid increased TLR4 expression promoting resistin signaling through TLR4 up-regulation and its recruitment to membrane lipid rafts.

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