901
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Agnihotri N, Chowdhury AD, De A. Non-enzymatic electrochemical detection of cholesterol using β-cyclodextrin functionalized graphene. Biosens Bioelectron 2015; 63:212-217. [DOI: 10.1016/j.bios.2014.07.037] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/17/2014] [Accepted: 07/18/2014] [Indexed: 10/25/2022]
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902
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Abstract
Epidemiologic and experimental data suggest the involvement of cholesterol metabolism in the development and progression of Alzheimer disease and Niemann-Pick type C disease, but not of frontotemporal dementias. In these 3 neurodegenerative diseases, however, protein tau hyperphosphorylation and aggregation into neurofibrillary tangles are observed. To elucidate the relationship between cholesterol and tau, we compared sterol levels of neurons burdened with neurofibrillary tangles with those of their unaffected neighbors using semiquantitative filipin fluorescence microscopy in mice expressing P301L mutant human tau (a well-described model of FTDP-17) and in P301L transgenic mice lacking apolipoprotein E (the major cholesterol transporter in the brain). Cellular unesterified cholesterol was higher in neurons affected by tau pathology irrespective of apolipoprotein E deficiency. This argues for an impact of tau pathology on cellular cholesterol homeostasis. We suggest that there is a bidirectional mode of action: Disturbances in cellular cholesterol metabolism may promote tau pathology, but tau pathology may also alter neuronal cholesterol homeostasis; once it is established, a vicious cycle may promote neurofibrillary tangle formation.
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903
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Targeting cellular squalene synthase, an enzyme essential for cholesterol biosynthesis, is a potential antiviral strategy against hepatitis C virus. J Virol 2014; 89:2220-32. [PMID: 25473062 DOI: 10.1128/jvi.03385-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) exploits host membrane cholesterol and its metabolism for progeny virus production. Here, we examined the impact of targeting cellular squalene synthase (SQS), the first committed enzyme for cholesterol biosynthesis, on HCV production. By using the HCV JFH-1 strain and human hepatoma Huh-7.5.1-derived cells, we found that the SQS inhibitors YM-53601 and zaragozic acid A decreased viral RNA, protein, and progeny production in HCV-infected cells without affecting cell viability. Similarly, small interfering RNA (siRNA)-mediated knockdown of SQS led to significantly reduced HCV production, confirming the enzyme as an antiviral target. A metabolic labeling study demonstrated that YM-53601 suppressed the biosynthesis of cholesterol and cholesteryl esters at antiviral concentrations. Unlike YM-53601, the cholesterol esterification inhibitor Sandoz 58-035 did not exhibit an antiviral effect, suggesting that biosynthesis of cholesterol is more important than that of cholesteryl esters for HCV production. YM-53601 inhibited transient replication of a JFH-1 subgenomic replicon and entry of JFH-1 pseudoparticles, suggesting that at least suppression of viral RNA replication and entry contributes to the antiviral effect of the drug. Collectively, our findings highlight the importance of the cholesterol biosynthetic pathway in HCV production and implicate SQS as a potential target for antiviral strategies against HCV. IMPORTANCE Hepatitis C virus (HCV) is known to be closely associated with host cholesterol and its metabolism throughout the viral life cycle. However, the impact of targeting cholesterol biosynthetic enzymes on HCV production is not fully understood. We found that squalene synthase, the first committed enzyme for cholesterol biosynthesis, is important for HCV production, and we propose this enzyme as a potential anti-HCV target. We provide evidence that synthesis of free cholesterol is more important than that of esterified cholesterol for HCV production, highlighting a marked free cholesterol dependency of HCV production. Our findings also offer a new insight into a role of the intracellular cholesterol pool that is coupled to its biosynthesis in the HCV life cycle.
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904
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Ueda Y, Ishitsuka R, Hullin-Matsuda F, Kobayashi T. Regulation of the transbilayer movement of diacylglycerol in the plasma membrane. Biochimie 2014; 107 Pt A:43-50. [DOI: 10.1016/j.biochi.2014.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/09/2014] [Indexed: 12/27/2022]
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905
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Mitochondrial cholesterol: mechanisms of import and effects on mitochondrial function. J Bioenerg Biomembr 2014; 48:137-51. [PMID: 25425472 DOI: 10.1007/s10863-014-9592-6] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 11/14/2014] [Indexed: 12/23/2022]
Abstract
Mitochondria require cholesterol for biogenesis and membrane maintenance, and for the synthesis of steroids, oxysterols and hepatic bile acids. Multiple pathways mediate the transport of cholesterol from different subcellular pools to mitochondria. In steroidogenic cells, the steroidogenic acute regulatory protein (StAR) interacts with a mitochondrial protein complex to mediate cholesterol delivery to the inner mitochondrial membrane for conversion to pregnenolone. In non-steroidogenic cells, several members of a protein family defined by the presence of a StAR-related lipid transfer (START) domain play key roles in the delivery of cholesterol to mitochondrial membranes. Subdomains of the endoplasmic reticulum (ER), termed mitochondria-associated ER membranes (MAM), form membrane contact sites with mitochondria and may contribute to the transport of ER cholesterol to mitochondria, either independently or in conjunction with lipid-transfer proteins. Model systems of mitochondria enriched with cholesterol in vitro and mitochondria isolated from cells with (patho)physiological mitochondrial cholesterol accumulation clearly demonstrate that mitochondrial cholesterol levels affect mitochondrial function. Increased mitochondrial cholesterol levels have been observed in several diseases, including cancer, ischemia, steatohepatitis and neurodegenerative diseases, and influence disease pathology. Hence, a deeper understanding of the mechanisms maintaining mitochondrial cholesterol homeostasis may reveal additional targets for therapeutic intervention. Here we give a brief overview of mitochondrial cholesterol import in steroidogenic cells, and then focus on cholesterol trafficking pathways that deliver cholesterol to mitochondrial membranes in non-steroidogenic cells. We also briefly discuss the consequences of increased mitochondrial cholesterol levels on mitochondrial function and their potential role in disease pathology.
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906
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Rhinovirus uses a phosphatidylinositol 4-phosphate/cholesterol counter-current for the formation of replication compartments at the ER-Golgi interface. Cell Host Microbe 2014; 16:677-90. [PMID: 25525797 DOI: 10.1016/j.chom.2014.10.003] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/19/2014] [Accepted: 09/23/2014] [Indexed: 12/19/2022]
Abstract
Similar to other positive-strand RNA viruses, rhinovirus, the causative agent of the common cold, replicates on a web of cytoplasmic membranes, orchestrated by host proteins and lipids. The host pathways that facilitate the formation and function of the replication membranes and complexes are poorly understood. We show that rhinovirus replication depends on host factors driving phosphatidylinositol 4-phosphate (PI4P)-cholesterol counter-currents at viral replication membranes. Depending on the virus type, replication required phosphatidylinositol 4-kinase class 3beta (PI4K3b), cholesteryl-esterase hormone-sensitive lipase (HSL) or oxysterol-binding protein (OSBP)-like 1, 2, 5, 9, or 11 associated with lipid droplets, endosomes, or Golgi. Replication invariably required OSBP1, which shuttles cholesterol and PI4P between ER and Golgi at membrane contact sites. Infection also required ER-associated PI4P phosphatase Sac1 and phosphatidylinositol (PI) transfer protein beta (PITPb) shunting PI between ER-Golgi. These data support a PI4P-cholesterol counter-flux model for rhinovirus replication.
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907
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α, ω-Cholesterol-functionalized low molecular weight polyethylene glycol as a novel modifier of cationic liposomes for gene delivery. Int J Mol Sci 2014; 15:20339-54. [PMID: 25383677 PMCID: PMC4264170 DOI: 10.3390/ijms151120339] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/25/2014] [Accepted: 09/30/2014] [Indexed: 02/05/2023] Open
Abstract
Here, three novel cholesterol (Ch)/low molecular weight polyethylene glycol (PEG) conjugates, termed α, ω-cholesterol-functionalized PEG (Ch2-PEGn), were successfully synthesized using three kinds of PEG with different average molecular weight (PEG600, PEG1000 and PEG2000). The purpose of the study was to investigate the potential application of novel cationic liposomes (Ch2-PEGn-CLs) containing Ch2-PEGn in gene delivery. The introduction of Ch2-PEGn affected both the particle size and zeta potential of cationic liposomes. Ch2-PEG2000 effectively compressed liposomal particles and Ch2-PEG2000-CLs were of the smallest size. Ch2-PEG1000 and Ch2-PEG2000 significantly decreased zeta potentials of Ch2-PEGn-CLs, while Ch2-PEG600 did not alter the zeta potential due to the short PEG chain. Moreover, the in vitro gene transfection efficiencies mediated by different Ch2-PEGn-CLs also differed, in which Ch2-PEG600-CLs achieved the strongest GFP expression than Ch2-PEG1000-CLs and Ch2-PEG2000-CLs in SKOV-3 cells. The gene delivery efficacy of Ch2-PEGn-CLs was further examined by addition of a targeting moiety (folate ligand) in both folate-receptor (FR) overexpressing SKOV-3 cells and A549 cells with low expression of FR. For Ch2-PEG1000-CLs and Ch2-PEG2000-CLs, higher molar ratios of folate ligand resulted in enhanced transfection efficacies, but Ch2-PEG600-CLs had no similar in contrast. Additionally, MTT assay proved the reduced cytotoxicities of cationic liposomes after modification by Ch2-PEGn. These findings provide important insights into the effects of Ch2-PEGn on cationic liposomes for delivering genes, which would be beneficial for the development of Ch2-PEGn-CLs-based gene delivery system.
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908
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Advanced experimental methods toward understanding biophysicochemical interactions of interfacial biomolecules by using sum frequency generation vibrational spectroscopy. Sci China Chem 2014. [DOI: 10.1007/s11426-014-5233-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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909
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Engineered liposomes sequester bacterial exotoxins and protect from severe invasive infections in mice. Nat Biotechnol 2014; 33:81-8. [PMID: 25362245 DOI: 10.1038/nbt.3037] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 09/09/2014] [Indexed: 12/25/2022]
Abstract
Gram-positive bacterial pathogens that secrete cytotoxic pore-forming toxins, such as Staphylococcus aureus and Streptococcus pneumoniae, cause a substantial burden of disease. Inspired by the principles that govern natural toxin-host interactions, we have engineered artificial liposomes that are tailored to effectively compete with host cells for toxin binding. Liposome-bound toxins are unable to lyse mammalian cells in vitro. We use these artificial liposomes as decoy targets to sequester bacterial toxins that are produced during active infection in vivo. Administration of artificial liposomes within 10 h after infection rescues mice from septicemia caused by S. aureus and S. pneumoniae, whereas untreated mice die within 24-33 h. Furthermore, liposomes protect mice against invasive pneumococcal pneumonia. Composed exclusively of naturally occurring lipids, tailored liposomes are not bactericidal and could be used therapeutically either alone or in conjunction with antibiotics to combat bacterial infections and to minimize toxin-induced tissue damage that occurs during bacterial clearance.
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910
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ARAS E, İŞLEK Y, KARATAŞ O, ABBASS HK, BİREY M, KILIÇ A. EPR study of γ-irradiated cholesteryl methyl carbonate. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.07.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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911
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Zhang CY, Xiong D, Sun Y, Zhao B, Lin WJ, Zhang LJ. Self-assembled micelles based on pH-sensitive PAE-g-MPEG-cholesterol block copolymer for anticancer drug delivery. Int J Nanomedicine 2014; 9:4923-33. [PMID: 25364250 PMCID: PMC4211906 DOI: 10.2147/ijn.s69493] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A novel amphiphilic triblock pH-sensitive poly(β-amino ester)-g-poly(ethylene glycol) methyl ether-cholesterol (PAE-g-MPEG-Chol) was designed and synthesized via the Michael-type step polymerization and esterification condensation method. The synthesized copolymer was determined with proton nuclear magnetic resonance and gel permeation chromatography. The grafting percentages of MPEG and cholesterol were determined as 10.93% and 62.02%, calculated from the area of the characteristic peaks, respectively. The amphiphilic copolymer was confirmed to self-assemble into core/shell micelles in aqueous solution at low concentrations. The critical micelle concentrations were 6.92 and 15.14 mg/L at pH of 7.4 and 6.0, respectively, obviously influenced by the changes of pH values. The solubility of pH-responsive PAE segment could be transformed depending on the different values of pH because of protonation–deprotonation of the amino groups, resulting in pH sensitivity of the copolymer. The average particle size of micelles increased from 125 nm to 165 nm with the pH decreasing, and the zeta potential was also significantly changed. Doxorubicin (DOX) was entrapped into the polymeric micelles with a high drug loading level. The in vitro DOX release from the micelles was distinctly enhanced with the pH decreasing from 7.4 to 6.0. Toxicity testing proved that the DOX-loaded micelles exhibited high cytotoxicity in HepG2 cells, whereas the copolymer showed low toxicity. The results demonstrated how pH-sensitive PAE-g-MPEG-Chol micelles were proved to be a potential vector in hydrophobic drug delivery for tumor therapy.
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Affiliation(s)
- Can Yang Zhang
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
| | - Di Xiong
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
| | - Yao Sun
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
| | - Bin Zhao
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
| | - Wen Jing Lin
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
| | - Li Juan Zhang
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong Province, People's Republic of China
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912
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Abstract
Cholesterol and components of the cholesterol biosynthetic pathway have fundamental roles in all mammalian cells. Hydroxylated forms of cholesterol are now emerging as important regulators of immune function. This involves effects on the cholesterol biosynthetic pathway and cell membrane properties, which can have antiviral and anti-inflammatory influences. In addition, a dihydroxylated form of cholesterol functions as an immune cell guidance cue by engaging the G protein-coupled receptor EBI2, and it is required for mounting adaptive immune responses. In this Review, we summarize the current understanding of the closely related oxysterols 25-hydroxycholesterol and 7α,25-dihydroxycholesterol, and the growing evidence that they have wide-ranging influences on innate and adaptive immunity.
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913
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Arya N, Kharjul MD, Shishoo CJ, Thakare VN, Jain KS. Some molecular targets for antihyperlipidemic drug research. Eur J Med Chem 2014; 85:535-68. [DOI: 10.1016/j.ejmech.2014.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 08/01/2014] [Accepted: 08/05/2014] [Indexed: 12/17/2022]
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914
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Martín MG, Pfrieger F, Dotti CG. Cholesterol in brain disease: sometimes determinant and frequently implicated. EMBO Rep 2014; 15:1036-52. [PMID: 25223281 DOI: 10.15252/embr.201439225] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cholesterol is essential for neuronal physiology, both during development and in the adult life: as a major component of cell membranes and precursor of steroid hormones, it contributes to the regulation of ion permeability, cell shape, cell-cell interaction, and transmembrane signaling. Consistently, hereditary diseases with mutations in cholesterol-related genes result in impaired brain function during early life. In addition, defects in brain cholesterol metabolism may contribute to neurological syndromes, such as Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD), and even to the cognitive deficits typical of the old age. In these cases, brain cholesterol defects may be secondary to disease-causing elements and contribute to the functional deficits by altering synaptic functions. In the first part of this review, we will describe hereditary and non-hereditary causes of cholesterol dyshomeostasis and the relationship to brain diseases. In the second part, we will focus on the mechanisms by which perturbation of cholesterol metabolism can affect synaptic function.
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Affiliation(s)
- Mauricio G Martín
- Instituto de Investigaciones Médicas Mercedes y Martín Ferreyra (INIMEC-CONICET-UNC), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Frank Pfrieger
- Institute of Cellular and Integrative Neurosciences, CNRS UPR 3212, University of Strasbourg, Strasbourg, France
| | - Carlos G Dotti
- Centro Biología Molecular 'Severo Ochoa' CSIC-UAM, Madrid, Spain
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915
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Differential inhibition of host cell cholesterol de novo biosynthesis and processing abrogates Eimeria bovis intracellular development. Parasitol Res 2014; 113:4165-76. [DOI: 10.1007/s00436-014-4092-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/22/2014] [Indexed: 10/24/2022]
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916
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Yamasaki T, Suzuki A, Hasebe R, Horiuchi M. Comparison of the anti-prion mechanism of four different anti-prion compounds, anti-PrP monoclonal antibody 44B1, pentosan polysulfate, chlorpromazine, and U18666A, in prion-infected mouse neuroblastoma cells. PLoS One 2014; 9:e106516. [PMID: 25181483 PMCID: PMC4152300 DOI: 10.1371/journal.pone.0106516] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/04/2014] [Indexed: 01/07/2023] Open
Abstract
Molecules that inhibit the formation of an abnormal isoform of prion protein (PrPSc) in prion-infected cells are candidate therapeutic agents for prion diseases. Understanding how these molecules inhibit PrPSc formation provides logical basis for proper evaluation of their therapeutic potential. In this study, we extensively analyzed the effects of the anti-PrP monoclonal antibody (mAb) 44B1, pentosan polysulfate (PPS), chlorpromazine (CPZ) and U18666A on the intracellular dynamics of a cellular isoform of prion protein (PrPC) and PrPSc in prion-infected mouse neuroblastoma cells to re-evaluate the effects of those agents. MAb 44B1 and PPS rapidly reduced PrPSc levels without altering intracellular distribution of PrPSc. PPS did not change the distribution and levels of PrPC, whereas mAb 44B1 appeared to inhibit the trafficking of cell surface PrPC to organelles in the endocytic-recycling pathway that are thought to be one of the sites for PrPSc formation. In contrast, CPZ and U18666A initiated the redistribution of PrPSc from organelles in the endocytic-recycling pathway to late endosomes/lysosomes without apparent changes in the distribution of PrPC. The inhibition of lysosomal function by monensin or bafilomycin A1 after the occurrence of PrPSc redistribution by CPZ or U18666A partly antagonized PrPSc degradation, suggesting that the transfer of PrPSc to late endosomes/lysosomes, possibly via alteration of the membrane trafficking machinery of cells, leads to PrPSc degradation. This study revealed that precise analysis of the intracellular dynamics of PrPC and PrPSc provides important information for understanding the mechanism of anti-prion agents.
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Affiliation(s)
- Takeshi Yamasaki
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Akio Suzuki
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Rie Hasebe
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Motohiro Horiuchi
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
- * E-mail:
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917
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Eltoukhy AA, Sahay G, Cunningham JM, Anderson DG. Niemann-Pick C1 affects the gene delivery efficacy of degradable polymeric nanoparticles. ACS NANO 2014; 8:7905-13. [PMID: 25010491 PMCID: PMC4148171 DOI: 10.1021/nn501630h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/10/2014] [Indexed: 05/15/2023]
Abstract
Despite intensive research effort, the rational design of improved nanoparticulate drug carriers remains challenging, in part due to a limited understanding of the determinants of nanoparticle entry and transport in target cells. Recent studies have shown that Niemann-Pick C1 (NPC1), the lysosome membrane protein that mediates trafficking of cholesterol in cells, is involved in the endosomal escape and subsequent infection caused by filoviruses, and that its absence promotes the retention and efficacy of lipid nanoparticles encapsulating siRNA. Here, we report that NPC1 deficiency results in dramatic reduction in internalization and transfection efficiency mediated by degradable cationic gene delivery polymers, poly(β-amino ester)s (PBAEs). PBAEs utilized cholesterol and dynamin-dependent endocytosis pathways, and these were found to be heavily compromised in NPC1-deficient cells. In contrast, the absence of NPC1 had minor effects on DNA uptake mediated by polyethylenimine or Lipofectamine 2000. Strikingly, stable overexpression of human NPC1 in chinese hamster ovary cells was associated with enhanced gene uptake (3-fold) and transfection (10-fold) by PBAEs. These findings reveal a role of NPC1 in the regulation of endocytic mechanisms affecting nanoparticle trafficking. We hypothesize that in-depth understanding sites of entry and endosomal escape may lead to highly efficient nanotechnologies for drug delivery.
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Affiliation(s)
- Ahmed A. Eltoukhy
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gaurav Sahay
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - James M. Cunningham
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Daniel G. Anderson
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Harvard-MIT Division of Health Sciences and Technology, and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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918
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Neuvonen M, Manna M, Mokkila S, Javanainen M, Rog T, Liu Z, Bittman R, Vattulainen I, Ikonen E. Enzymatic oxidation of cholesterol: properties and functional effects of cholestenone in cell membranes. PLoS One 2014; 9:e103743. [PMID: 25157633 PMCID: PMC4144813 DOI: 10.1371/journal.pone.0103743] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
Bacterial cholesterol oxidase is commonly used as an experimental tool to reduce cellular cholesterol content. That the treatment also generates the poorly degradable metabolite 4-cholesten-3-one (cholestenone) has received less attention. Here, we investigated the membrane partitioning of cholestenone using simulations and cell biological experiments and assessed the functional effects of cholestenone in human cells. Atomistic simulations predicted that cholestenone reduces membrane order, undergoes faster flip-flop and desorbs more readily from membranes than cholesterol. In primary human fibroblasts, cholestenone was released from membranes to physiological extracellular acceptors more avidly than cholesterol, but without acceptors it remained in cells over a day. To address the functional effects of cholestenone, we studied fibroblast migration during wound healing. When cells were either cholesterol oxidase treated or part of cellular cholesterol was exchanged for cholestenone with cyclodextrin, cell migration during 22 h was markedly inhibited. Instead, when a similar fraction of cholesterol was removed using cyclodextrin, cells replenished their cholesterol content in 3 h and migrated similarly to control cells. Thus, cholesterol oxidation produces long-term functional effects in cells and these are in part due to the generated membrane active cholestenone.
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Affiliation(s)
- Maarit Neuvonen
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland
| | - Moutusi Manna
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Sini Mokkila
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Matti Javanainen
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Tomasz Rog
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Zheng Liu
- Department of Chemistry and Biochemistry, Queens College, The City University of New York, Flushing, NY, United States of America
| | - Robert Bittman
- Department of Chemistry and Biochemistry, Queens College, The City University of New York, Flushing, NY, United States of America
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, Tampere, Finland
- MEMPHYS – Center of Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | - Elina Ikonen
- Institute of Biomedicine, Anatomy, University of Helsinki, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- * E-mail:
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919
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Flinner N, Mirus O, Schleiff E. The influence of fatty acids on the GpA dimer interface by coarse-grained molecular dynamics simulation. Int J Mol Sci 2014; 15:14247-68. [PMID: 25196522 PMCID: PMC4159849 DOI: 10.3390/ijms150814247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/14/2014] [Accepted: 08/06/2014] [Indexed: 11/17/2022] Open
Abstract
The hydrophobic thickness of membranes, which is manly defined by fatty acids, influences the packing of transmembrane domains of proteins and thus can modulate the activity of these proteins. We analyzed the dynamics of the dimerization of Glycophorin A (GpA) by molecular dynamics simulations to describe the fatty acid dependence of the transmembrane region assembly. GpA represents a well-established model for dimerization of single transmembrane helices containing a GxxxG motif in vitro and in silico. We performed simulations of the dynamics of the NMR-derived dimer as well as self-assembly simulations of monomers in membranes composed of different fatty acid chains and monitored the formed interfaces and their transitions. The observed dimeric interfaces, which also include the one known from NMR, are highly dynamic and converted into each other. The frequency of interface formation and the preferred transitions between interfaces similar to the interface observed by NMR analysis strongly depend on the fatty acid used to build the membrane. Molecular dynamic simulations after adaptation of the helix topology parameters to better represent NMR derived structures of single transmembrane helices yielded an enhanced occurrence of the interface determined by NMR in molecular dynamics simulations. Taken together we give insights into the influence of fatty acids and helix conformation on the dynamics of the transmembrane domain of GpA.
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Affiliation(s)
- Nadine Flinner
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
| | - Oliver Mirus
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
| | - Enrico Schleiff
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
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920
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Liu J, Xian G, Li M, Zhang Y, Yang M, Yu Y, Lv H, Xuan S, Lin Y, Gao L. Cholesterol oxidase from Bordetella species promotes irreversible cell apoptosis in lung adenocarcinoma by cholesterol oxidation. Cell Death Dis 2014; 5:e1372. [PMID: 25118932 PMCID: PMC4454300 DOI: 10.1038/cddis.2014.324] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 06/24/2014] [Accepted: 06/26/2014] [Indexed: 12/28/2022]
Abstract
Cholesterol oxidase (COD), an enzyme catalyzing the oxidation of cholesterol, has been applied to track the distribution of membrane cholesterol. Little investigations about the effect of COD on tumor cells have been performed. In the present study, we provided evidence that COD from Bordetella species (COD-B), induced apoptosis of lung cancer cells in vitro and in vivo. COD-B treatment inhibited Akt and ERK1/2 phosphorylation in dose- and time-dependent manner, which was not reversed and was even aggravated by cholesterol addition. Further investigation indicated that COD-B treatment promoted the generation of reactive oxygen species (ROS) and that cholesterol addition further elevated ROS levels. Moreover, COD-B treatment resulted in JNK and p38 phosphorylation, downregulation of Bcl-2, upregulation of Bax, activated caspase-3 and cytochrome C release, which likely responded to freshly produced hydrogen peroxide that accompanied cholesterol oxidation. Catalase pretreatment could only partially prevent COD-B-induced events, suggesting that catalase inhibited H2O2-induced signal transduction but had little effect on signal pathways involved in cholesterol depletion. Our results demonstrated that COD-B led to irreversible cell apoptosis by decreasing cholesterol content and increasing ROS level. In addition, COD-B may be a promising candidate for a novel anti-tumor therapy.
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Affiliation(s)
- J Liu
- Department of General Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - G Xian
- Department of General Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - M Li
- Department of Cardiology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Y Zhang
- Department of Obstetrics, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - M Yang
- Department of Ultrasound, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Y Yu
- Department of Ultrasound, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - H Lv
- Department of Obstetrics, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - S Xuan
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong Province 250021, China
| | - Y Lin
- Department of Center Laboratory, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - L Gao
- 1] Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong Province 250021, China [2] Department of Center Laboratory, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
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921
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Lammi C, Zanoni C, Arnoldi A. A simple and high-throughput in-cell Western assay using HepG2 cell line for investigating the potential hypocholesterolemic effects of food components and nutraceutics. Food Chem 2014; 169:59-64. [PMID: 25236198 DOI: 10.1016/j.foodchem.2014.07.133] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 07/25/2014] [Accepted: 07/28/2014] [Indexed: 01/28/2023]
Abstract
Since saving time and money are critical issues while developing innovative functional foods and nutraceutics, the use of specific and high-throughput assays for the fast screening of potentially bioactive ingredients is crucial. In this context, the aim of the present investigation was the development of an in-cell Western (ICW) assay, a quantitative colorimetric cell-based technique, at the HepG2 cell line for screening and evaluating the effects of potentially bioactive compounds on the low density lipoprotein (LDL) receptor (LDLR). It is known that LDLR plays a pivotal role in the binding and endocytosis of circulating LDL, increasing its plasma clearance. The ICW was optimised and validated using monacolin K, the main hypocholesterolemic component of red yeast rice. This provided a robust and reproducible assay useful for characterising the cholesterol-lowering properties of bioactive food components. To our knowledge, this is the first application of the ICW technique in the field of functional foods and nutraceutics.
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Affiliation(s)
- Carmen Lammi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milan, Italy
| | - Chiara Zanoni
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milan, Italy
| | - Anna Arnoldi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Milan, Italy.
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922
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Is Alzheimer's disease related to metabolic syndrome? A Wnt signaling conundrum. Prog Neurobiol 2014; 121:125-46. [PMID: 25084549 DOI: 10.1016/j.pneurobio.2014.07.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/17/2014] [Accepted: 07/23/2014] [Indexed: 01/07/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 36 million people worldwide. AD is characterized by a progressive loss of cognitive functions. For years, it has been thought that age is the main risk factor for AD. Recent studies suggest that life style factors, including nutritional behaviors, play a critical role in the onset of dementia. Evidence about the relationship between nutritional behavior and AD includes the role of conditions such as obesity, hypertension, dyslipidemia and elevated glucose levels. The coexistence of some of these cardio-metabolic risk factors is generally known as metabolic syndrome (MS). Some clinical studies support the role of MS in the onset of AD. However, the cross-talk between the molecular signaling implicated in these disorders is unknown. In the present review, we focus on the molecular correlates that support the relationship between MS and the onset of AD. We also discuss relevant issues such as the role of leptin, insulin and renin-angiotensin signaling in the brain and the possible role of Wnt signaling in both MS and AD. We discuss the evidence supporting the use of ob/ob mice, high-fructose diets, aortic coarctation-induced hypertension and Octodon degus, which spontaneously develops β-amyloid deposits and metabolic derangements, as suitable animal models to address the relationships between MS and AD. Finally, we examine emergent data supporting the role of Wnt signaling in the modulation of AD and MS, implicating this pathway as a therapeutic target in both conditions.
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923
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Degirolamo C, Sabbà C, Moschetta A. Intestinal nuclear receptors in HDL cholesterol metabolism. J Lipid Res 2014; 56:1262-70. [PMID: 25070952 DOI: 10.1194/jlr.r052704] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Indexed: 12/18/2022] Open
Abstract
The intestine plays a pivotal role in cholesterol homeostasis by functioning as an absorptive and secretory organ in the reverse cholesterol transport pathway. Enterocytes control cholesterol absorption, apoAI synthesis, HDL biogenesis, and nonbiliary cholesterol fecal disposal. Thus, intestine-based therapeutic interventions may hold promise in the management of diseases driven by cholesterol overload. Lipid-sensing nuclear receptors (NRs) are highly expressed in the intestinal epithelium and regulate transcriptionally the handling of cholesterol by the enterocytes. Here, we discuss the NR regulation of cholesterol fluxes across the enterocytes with special emphasis on NR exploitation as a bona fide novel HDL-raising strategy.
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Affiliation(s)
- Chiara Degirolamo
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori "Giovanni Paolo II", 70124 Bari, Italy
| | - Carlo Sabbà
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", 70124 Bari, Italy
| | - Antonio Moschetta
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori "Giovanni Paolo II", 70124 Bari, Italy Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", 70124 Bari, Italy
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924
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Ibupoto ZH, Elhag S, Nur O, Willander M. Fabrication of Sensitive Potentiometric Cholesterol Biosensor Based on Co3O4Interconnected Nanowires. ELECTROANAL 2014. [DOI: 10.1002/elan.201400192] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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925
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Egg intake during carbohydrate restriction alters peripheral blood mononuclear cell inflammation and cholesterol homeostasis in metabolic syndrome. Nutrients 2014; 6:2650-67. [PMID: 25045936 PMCID: PMC4113762 DOI: 10.3390/nu6072650] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 07/02/2014] [Accepted: 07/08/2014] [Indexed: 01/14/2023] Open
Abstract
Egg yolk contains bioactive components that improve plasma inflammatory markers and HDL profiles in metabolic syndrome (MetS) under carbohydrate restriction. We further sought to determine whether egg yolk intake affects peripheral blood mononuclear cell (PBMC) inflammation and cholesterol homeostasis in MetS, as HDL and its associated lipid transporter ATP-binding cassette transporter A1 (ABCA1) reduce the inflammatory potential of leukocytes through modulation of cellular cholesterol content and distribution. Thirty-seven men and women classified with MetS consumed a moderate carbohydrate-restricted diet (25%–30% of energy) for 12 weeks, in addition to consuming either three whole eggs per day (EGG) or the equivalent amount of yolk-free egg substitute (SUB). Interestingly, lipopolysaccharide-induced PBMC IL-1β and TNFα secretion increased from baseline to week 12 in the SUB group only, despite increases in PBMC toll-like receptor 4 (TLR4) mRNA expression in the EGG group. Compared to baseline, ABCA1 and 3-hydroxy-3-methyl-glutaryl (HMG)-CoA reductase mRNA expression increased by week 12 in the EGG group only, whereas changes in PBMC total cholesterol positively correlated with changes in lipid raft content. Together, these findings suggest that intake of whole eggs during carbohydrate restriction alters PBMC inflammation and cholesterol homeostasis in MetS.
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926
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Prabhu AV, Sharpe LJ, Brown AJ. The sterol-based transcriptional control of human 7-dehydrocholesterol reductase (DHCR7): Evidence of a cooperative regulatory program in cholesterol synthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1431-9. [PMID: 25048193 DOI: 10.1016/j.bbalip.2014.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 06/20/2014] [Accepted: 07/07/2014] [Indexed: 02/01/2023]
Abstract
The enzyme 7-dehydrocholesterol reductase (DHCR7) catalyzes the final step of cholesterol synthesis via the Kandutsch-Russell pathway, and is crucial in maintaining cellular cholesterol levels. Its absence leads to the devastating fetal developmental disorder Smith-Lemli-Opitz Syndrome (SLOS). How this enzyme is regulated has implications in controlling not only cholesterol synthesis, but also the synthesis of Vitamin D - another product of 7-dehydrocholesterol. In this study, we look specifically at how DHCR7 is regulated by the sterol regulatory element-binding protein-2 (SREBP-2) transcription factor. Sterol regulation has previously been studied in the rat DHCR7 promoter, but we have found that its regulatory elements are not all conserved in humans. Rather, the human promoter contains two binding sites for SREBP-2 (at -155 and -55) and a binding site for the nuclear factor-Y (NF-Y) cofactor (at -136). The -155 site is a particularly responsive sterol regulatory element (SRE) which is well conserved in mammals, and was possibly overlooked in the rat promoter study. The exact location of the weaker -55 site (close to the known rat SRE) may have shifted during evolution. Furthermore, we established that the two SREs that bind SREBP-2 work in cooperation to synergistically activate DHCR7. We have previously characterized the SREs in DHCR24, the final enzyme in the alternate Bloch pathway of cholesterol synthesis. Here, comparison of the sterol regulation of these terminal enzymes demonstrates the unique cooperative system that helps to control cholesterol synthesis.
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Affiliation(s)
- Anika V Prabhu
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Laura J Sharpe
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
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927
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Sheng R, Kim H, Lee H, Xin Y, Chen Y, Tian W, Cui Y, Choi JC, Doh J, Han JK, Cho W. Cholesterol selectively activates canonical Wnt signalling over non-canonical Wnt signalling. Nat Commun 2014; 5:4393. [PMID: 25024088 PMCID: PMC4100210 DOI: 10.1038/ncomms5393] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 06/13/2014] [Indexed: 12/19/2022] Open
Abstract
Wnt proteins control diverse biological processes through β-catenin-dependent canonical signalling and β-catenin-independent non-canonical signalling. The mechanisms by which these signalling pathways are differentially triggered and controlled are not fully understood. Dishevelled (Dvl) is a scaffold protein that serves as the branch point of these pathways. Here, we show that cholesterol selectively activates canonical Wnt signalling over non-canonical signalling under physiological conditions by specifically facilitating the membrane recruitment of the PDZ domain of Dvl and its interaction with other proteins. Single-molecule imaging analysis shows that cholesterol is enriched around the Wnt-activated Frizzled and low-density lipoprotein receptor-related protein 5/6 receptors and plays an essential role for Dvl-mediated formation and maintenance of the canonical Wnt signalling complex. Collectively, our results suggest a new regulatory role of cholesterol in Wnt signalling and a potential link between cellular cholesterol levels and the balance between canonical and non-canonical Wnt signalling activities.
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Affiliation(s)
- Ren Sheng
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | | | | | - Yao Xin
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yong Chen
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Wen Tian
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yang Cui
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Jong-Cheol Choi
- Mechanical Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Junsang Doh
- Mechanical Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | | | - Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
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928
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Essentially all excess fibroblast cholesterol moves from plasma membranes to intracellular compartments. PLoS One 2014; 9:e98482. [PMID: 25014655 PMCID: PMC4094430 DOI: 10.1371/journal.pone.0098482] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 05/02/2014] [Indexed: 11/19/2022] Open
Abstract
It has been shown that modestly increasing plasma membrane cholesterol beyond its physiological set point greatly increases the endoplasmic reticulum and mitochondrial pools, thereby eliciting manifold feedback responses that return cell cholesterol to its resting state. The question arises whether this homeostatic mechanism reflects the targeting of cell surface cholesterol to specific intracellular sites or its general equilibration among the organelles. We now show that human fibroblast cholesterol can be increased as much as two-fold from 2-hydroxypropyl-β-cyclodextrin without changing the size of the cell surface pool. Rather, essentially all of the added cholesterol disperses rapidly among cytoplasmic membranes, increasing their overall cholesterol content by as much as five-fold. We conclude that the level of plasma membrane cholesterol is normally at capacity and that even small increments above this physiological set point redistribute essentially entirely to intracellular membranes, perhaps down their chemical activity gradients.
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929
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Tripathi KM, Sonker AK, Sonkar SK, Sarkar S. Pollutant soot of diesel engine exhaust transformed to carbon dots for multicoloured imaging of E. coli and sensing cholesterol. RSC Adv 2014. [DOI: 10.1039/c4ra03720k] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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930
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Yesylevskyy SO, Ramseyer C. Determination of mean and Gaussian curvatures of highly curved asymmetric lipid bilayers: the case study of the influence of cholesterol on the membrane shape. Phys Chem Chem Phys 2014; 16:17052-61. [DOI: 10.1039/c4cp01544d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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931
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Midzak A, Papadopoulos V. Binding domain-driven intracellular trafficking of sterols for synthesis of steroid hormones, bile acids and oxysterols. Traffic 2014; 15:895-914. [PMID: 24890942 DOI: 10.1111/tra.12177] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 05/28/2014] [Accepted: 05/28/2014] [Indexed: 12/16/2022]
Abstract
Steroid hormones, bioactive oxysterols and bile acids are all derived from the biological metabolism of lipid cholesterol. The enzymatic pathways generating these compounds have been an area of intense research for almost a century, as cholesterol and its metabolites have substantial impacts on human health. Owing to its high degree of hydrophobicity and the chemical properties that it confers to biological membranes, the distribution of cholesterol in cells is tightly controlled, with subcellular organelles exhibiting highly divergent levels of cholesterol. The manners in which cells maintain such sterol distributions are of great interest in the study of steroid and bile acid synthesis, as limiting cholesterol substrate to the enzymatic pathways is the principal mechanism by which production of steroids and bile acids is regulated. The mechanisms by which cholesterol moves within cells, however, remain poorly understood. In this review, we examine the subcellular machinery involved in cholesterol metabolism to steroid hormones and bile acid, relating it to both lipid- and protein-based mechanisms facilitating intracellular and intraorganellar cholesterol movement and delivery to these pathways. In particular, we examine evidence for the involvement of specific protein domains involved in cholesterol binding, which impact cholesterol movement and metabolism in steroidogenesis and bile acid synthesis. A better understanding of the physical mechanisms by which these protein- and lipid-based systems function is of fundamental importance to understanding physiological homeostasis and its perturbation.
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Affiliation(s)
- Andrew Midzak
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada
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932
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Ribas V, García-Ruiz C, Fernández-Checa JC. Glutathione and mitochondria. Front Pharmacol 2014; 5:151. [PMID: 25024695 PMCID: PMC4079069 DOI: 10.3389/fphar.2014.00151] [Citation(s) in RCA: 352] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 06/10/2014] [Indexed: 12/16/2022] Open
Abstract
Glutathione (GSH) is the main non-protein thiol in cells whose functions are dependent on the redox-active thiol of its cysteine moiety that serves as a cofactor for a number of antioxidant and detoxifying enzymes. While synthesized exclusively in the cytosol from its constituent amino acids, GSH is distributed in different compartments, including mitochondria where its concentration in the matrix equals that of the cytosol. This feature and its negative charge at physiological pH imply the existence of specific carriers to import GSH from the cytosol to the mitochondrial matrix, where it plays a key role in defense against respiration-induced reactive oxygen species and in the detoxification of lipid hydroperoxides and electrophiles. Moreover, as mitochondria play a central strategic role in the activation and mode of cell death, mitochondrial GSH has been shown to critically regulate the level of sensitization to secondary hits that induce mitochondrial membrane permeabilization and release of proteins confined in the intermembrane space that once in the cytosol engage the molecular machinery of cell death. In this review, we summarize recent data on the regulation of mitochondrial GSH and its role in cell death and prevalent human diseases, such as cancer, fatty liver disease, and Alzheimer’s disease.
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Affiliation(s)
- Vicent Ribas
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona, Consejo Superior de Investigaciones Científicas (IIBB-CSIC) Barcelona, Spain ; Liver Unit, Hospital Clínic, Centre Esther Koplowitz, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)-Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Barcelona, Spain
| | - Carmen García-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona, Consejo Superior de Investigaciones Científicas (IIBB-CSIC) Barcelona, Spain ; Liver Unit, Hospital Clínic, Centre Esther Koplowitz, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)-Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Barcelona, Spain ; Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
| | - José C Fernández-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona, Consejo Superior de Investigaciones Científicas (IIBB-CSIC) Barcelona, Spain ; Liver Unit, Hospital Clínic, Centre Esther Koplowitz, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)-Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Barcelona, Spain ; Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
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933
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Hullin-Matsuda F, Taguchi T, Greimel P, Kobayashi T. Lipid compartmentalization in the endosome system. Semin Cell Dev Biol 2014; 31:48-56. [DOI: 10.1016/j.semcdb.2014.04.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 11/15/2022]
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934
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Guerrero I, Kornberg TB. Hedgehog and its circuitous journey from producing to target cells. Semin Cell Dev Biol 2014; 33:52-62. [PMID: 24994598 DOI: 10.1016/j.semcdb.2014.06.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/23/2014] [Indexed: 12/12/2022]
Abstract
The hedgehog (Hh) signaling protein has essential roles in the growth, development and regulation of many vertebrate and invertebrate organs. The processes that make Hh and prepare it for release from producing cells and that move it to target cells are both diverse and complex. This article reviews the essential features of these processes and highlights recent work that provides a novel framework to understand how these processes contribute to an integrated pathway.
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Affiliation(s)
- Isabel Guerrero
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain.
| | - Thomas B Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA.
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935
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Mignard V, Lalier L, Paris F, Vallette FM. Bioactive lipids and the control of Bax pro-apoptotic activity. Cell Death Dis 2014; 5:e1266. [PMID: 24874738 PMCID: PMC4047880 DOI: 10.1038/cddis.2014.226] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 12/19/2022]
Abstract
Lipids are key regulators of cell physiology through the control of many aspects of cellular life and survival. In particular, lipids have been implicated at different levels and through many different mechanisms in the cell death program called apoptosis. Here, we discuss the action of lipids in the regulation of the activation and the integration of Bax into the mitochondrial outer membrane, a key pro-apoptotic member of the BCL-2 family. We describe how, during apoptosis, lipids can act simultaneously or in parallel as receptors or ligands for Bax to stimulate or inhibit its pro-death activity.
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Affiliation(s)
- V Mignard
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
| | - L Lalier
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
| | - F Paris
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
| | - F M Vallette
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
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936
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Wang H, Blumberg JB, Chen CYO, Choi SW, Corcoran MP, Harris SS, Jacques PF, Kristo AS, Lai CQ, Lamon-Fava S, Matthan NR, McKay DL, Meydani M, Parnell LD, Prokopy MP, Scott TM, Lichtenstein AH. Dietary modulators of statin efficacy in cardiovascular disease and cognition. Mol Aspects Med 2014; 38:1-53. [PMID: 24813475 DOI: 10.1016/j.mam.2014.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/14/2014] [Accepted: 04/14/2014] [Indexed: 12/21/2022]
Abstract
Cardiovascular disease remains the leading cause of morbidity and mortality in the United States and other developed countries, and is fast growing in developing countries, particularly as life expectancy in all parts of the world increases. Current recommendations for the prevention of cardiovascular disease issued jointly from the American Academy of Cardiology and American Heart Association emphasize that lifestyle modification should be incorporated into any treatment plan, including those on statin drugs. However, there is a dearth of data on the interaction between diet and statins with respect to additive, complementary or antagonistic effects. This review collates the available data on the interaction of statins and dietary patterns, cognition, genetics and individual nutrients, including vitamin D, niacin, omega-3 fatty acids, fiber, phytochemicals (polyphenols and stanols) and alcohol. Of note, although the available data is summarized, the scope is limited, conflicting and disparate. In some cases it is likely there is unrecognized synergism. Virtually no data are available describing the interactions of statins with dietary components or dietary pattern in subgroups of the population, particularly those who may benefit most were positive effects identified. Hence, it is virtually impossible to draw any firm conclusions at this time. Nevertheless, this area is important because were the effects of statins and diet additive or synergistic harnessing the effect could potentially lead to the use of a lower intensity statin or dose.
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Affiliation(s)
- Huifen Wang
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Jeffrey B Blumberg
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - C-Y Oliver Chen
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Sang-Woon Choi
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA.
| | - Michael P Corcoran
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Susan S Harris
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Paul F Jacques
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Aleksandra S Kristo
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Chao-Qiang Lai
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Stefania Lamon-Fava
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Nirupa R Matthan
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Diane L McKay
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Mohsen Meydani
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Laurence D Parnell
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Max P Prokopy
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Tammy M Scott
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
| | - Alice H Lichtenstein
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA; Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA, USA
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937
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Reverter M, Rentero C, Garcia-Melero A, Hoque M, Vilà de Muga S, Alvarez-Guaita A, Conway JRW, Wood P, Cairns R, Lykopoulou L, Grinberg D, Vilageliu L, Bosch M, Heeren J, Blasi J, Timpson P, Pol A, Tebar F, Murray RZ, Grewal T, Enrich C. Cholesterol regulates Syntaxin 6 trafficking at trans-Golgi network endosomal boundaries. Cell Rep 2014; 7:883-97. [PMID: 24746815 DOI: 10.1016/j.celrep.2014.03.043] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 12/30/2013] [Accepted: 03/17/2014] [Indexed: 12/27/2022] Open
Abstract
Inhibition of cholesterol export from late endosomes causes cellular cholesterol imbalance, including cholesterol depletion in the trans-Golgi network (TGN). Here, using Chinese hamster ovary (CHO) Niemann-Pick type C1 (NPC1) mutant cell lines and human NPC1 mutant fibroblasts, we show that altered cholesterol levels at the TGN/endosome boundaries trigger Syntaxin 6 (Stx6) accumulation into VAMP3, transferrin, and Rab11-positive recycling endosomes (REs). This increases Stx6/VAMP3 interaction and interferes with the recycling of αVβ3 and α5β1 integrins and cell migration, possibly in a Stx6-dependent manner. In NPC1 mutant cells, restoration of cholesterol levels in the TGN, but not inhibition of VAMP3, restores the steady-state localization of Stx6 in the TGN. Furthermore, elevation of RE cholesterol is associated with increased amounts of Stx6 in RE. Hence, the fine-tuning of cholesterol levels at the TGN-RE boundaries together with a subset of cholesterol-sensitive SNARE proteins may play a regulatory role in cell migration and invasion.
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Affiliation(s)
- Meritxell Reverter
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Carles Rentero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Ana Garcia-Melero
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Monira Hoque
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Sandra Vilà de Muga
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Anna Alvarez-Guaita
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - James R W Conway
- Garvan Institute of Medical Research and Kinghorn Cancer Centre, Cancer Research Program, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Peta Wood
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Rose Cairns
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Lilia Lykopoulou
- First Department of Pediatrics, University of Athens, Aghia Sofia Children's Hospital, 11527 Athens, Greece
| | - Daniel Grinberg
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, CIBERER, IBUB, 08028 Barcelona, Spain
| | - Lluïsa Vilageliu
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, CIBERER, IBUB, 08028 Barcelona, Spain
| | - Marta Bosch
- Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Joerg Heeren
- Department of Biochemistry and Molecular Biology II. Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Juan Blasi
- Department of Pathology and Experimental Therapeutics, IDIBELL-University of Barcelona, L'Hospitalet de Llobregat, 08907 Barcelona, Spain
| | - Paul Timpson
- Garvan Institute of Medical Research and Kinghorn Cancer Centre, Cancer Research Program, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Albert Pol
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avaçats (ICREA), 08010 Barcelona, Spain
| | - Francesc Tebar
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Rachael Z Murray
- Tissue Repair and Regeneration Program, Institute of Health and Biomedical, Innovation, Queensland University of Technology, Brisbane, QLD 4095, Australia
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia.
| | - Carlos Enrich
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain; Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
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938
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Kalantarian S, Rimm EB, Herrington DM, Mozaffarian D. Dietary macronutrients, genetic variation, and progression of coronary atherosclerosis among women. Am Heart J 2014; 167:627-635.e1. [PMID: 24655714 DOI: 10.1016/j.ahj.2014.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 01/06/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND Previous studies observed the surprising finding that saturated fat was inversely associated with atherosclerosis progression in postmenopausal women, whereas polyunsaturated fat (PUFA) and carbohydrates were positively associated. Whether certain genes modify the association of diet with atherosclerotic progression is unknown. METHODS Using Haplotype-tagging single nucleotide polymorphisms, we evaluated gene-diet interactions with 3 preselected genes involved in fatty acid and carbohydrate metabolism: sterol regulatory element binding protein-1 (SREBP1), insulin-induced gene-1 (INSIG1), and SREBP cleavage-activating protein (SCAP). Diet was assessed at baseline. Quantitative coronary angiography was performed at baseline and after a mean of follow-up of 3.09 years in 2,227 coronary segments in 234 postmenopausal women. RESULTS Global effects of each gene and gene-diet interactions for different fats, total fat, and carbohydrate were evaluated. Global tests revealed no main effects between SCAP, INSIG1, and SREBP1 haplotypes and progression of atherosclerosis (P = .87, P = .58, and P = .44). After correction for 5 nutrients evaluated (Bonferroni-corrected 2-tailed α = .01), no significant gene-nutrient interactions were seen, except for a borderline global interaction between SREBP1 and PUFA intake (P interaction = .013). This interaction was specific to the G-C haplotype (frequency 35%) and was driven by n-6 rather than n-3 PUFA (P for interaction < .0001). The interaction was robust to estimated isocaloric replacement of PUFA with any other nutrient. Per each 5% energy from n-6 PUFA, a 0.21-mm greater decline in mean minimal coronary artery diameter was seen among women per each copy of the second most frequent haplotype of SREBP1. CONCLUSIONS We observed an interaction between SREBP1 and PUFA consumption that might explain the positive association of PUFA with atherosclerosis progression in this cohort.
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939
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Yamamura T, Ohsaki Y, Suzuki M, Shinohara Y, Tatematsu T, Cheng J, Okada M, Ohmiya N, Hirooka Y, Goto H, Fujimoto T. Inhibition of Niemann-Pick-type C1-like1 by ezetimibe activates autophagy in human hepatocytes and reduces mutant α1-antitrypsin Z deposition. Hepatology 2014; 59:1591-9. [PMID: 24214142 DOI: 10.1002/hep.26930] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 11/04/2013] [Indexed: 12/16/2022]
Abstract
UNLABELLED Autophagy can degrade aggregate-prone proteins, but excessive autophagy can have adverse effects. It would be beneficial if autophagy could be enhanced in a cell type-specific manner, but this has been difficult because the basic mechanism of autophagy is common. In the present study we found that inhibition of Niemann-Pick-type C1-like 1 (NPC1L1) by ezetimibe activates autophagy only in hepatocytes and small intestinal epithelia, but not in other cells. Ezetimibe induced accumulation of free cholesterol in the late endosome/lysosome and increased partitioning of a Ragulator component, LAMTOR1, in rafts. The latter change led to down-regulation of mammalian target of rapamycin (mTOR)C1 activity by decreasing mTOR recruitment to the late endosome/lysosome and activated autophagy. A primary effect of ezetimibe was found to be a decrease of free cholesterol in the plasma membrane, because all the results caused by ezetimibe were suppressed by supplementation of cholesterol as a methyl-β-cyclodextrin complex. By enhancing autophagy in human primary hepatocytes with ezetimibe, insoluble mutant α1-antitrypsin Z was reduced significantly. CONCLUSION Inhibition of NPC1L1 by ezetimibe activates autophagy in human hepatocytes by modulating cholesterol homeostasis. Ezetimibe may be used to ameliorate liver degeneration in α1-antitrypsin deficiency.
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Affiliation(s)
- Takeshi Yamamura
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan; Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
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940
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Ilnytska O, Santiana M, Hsu NY, Du WL, Chen YH, Viktorova EG, Belov G, Brinker A, Storch J, Moore C, Dixon JL, Altan-Bonnet N. Enteroviruses harness the cellular endocytic machinery to remodel the host cell cholesterol landscape for effective viral replication. Cell Host Microbe 2014; 14:281-93. [PMID: 24034614 DOI: 10.1016/j.chom.2013.08.002] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/02/2013] [Accepted: 08/01/2013] [Indexed: 12/20/2022]
Abstract
Cholesterol is a critical component of cellular membranes, regulating assembly and function of membrane-based protein/lipid complexes. Many RNA viruses, including enteroviruses, remodel host membranes to generate organelles with unique lipid blueprints on which they assemble replication complexes and synthesize viral RNA. Here we find that clathrin-mediated endocytosis (CME) is harnessed by enteroviruses to traffic cholesterol from the plasma membrane (PM) and extracellular medium to replication organelles, where cholesterol then regulates viral polyprotein processing and facilitates genome synthesis. When CME is disrupted, cellular cholesterol pools are instead stored in lipid droplets, cholesterol cannot be trafficked to replication organelles, and replication is inhibited. In contrast, replication is stimulated in cholesterol-elevated cells like those lacking caveolins or those from Niemann-Pick disease patients. Our findings indicate cholesterol as a critical determinant for enteroviral replication and outline roles for the endocytic machinery in both the enteroviral life cycle and host cell cholesterol homeostasis.
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Affiliation(s)
- Olha Ilnytska
- Laboratory of Host-Pathogen Dynamics, Rutgers University, Newark, NJ 07102, USA
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941
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Park EM, Nguyen LN, Lim YS, Hwang SB. Farnesyl-diphosphate farnesyltransferase 1 regulates hepatitis C virus propagation. FEBS Lett 2014; 588:1813-20. [PMID: 24690320 DOI: 10.1016/j.febslet.2014.03.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/11/2014] [Accepted: 03/21/2014] [Indexed: 01/23/2023]
Abstract
To identify the novel genes involved in lipid metabolism and lipid droplet formation that may play important roles in Hepatitis C virus (HCV) propagation, we have screened the small interfering RNA library using cell culture derived HCV (HCVcc)-infected cells. We selected and characterized the gene encoding farnesyl-diphosphate farnesyltransferase 1 (FDFT1). siRNA-mediated knockdown of FDFT1 impaired HCV replication in both subgenomic replicon and HCVcc infected cells. Moreover, YM-53601, an inhibitor of FDFT1 enzyme activity, abrogated HCV propagation. HCV infection increased FDFT1 protein level but not FDFT1 mRNA level. These results suggest that HCV may modulate FDFT1 protein level to facilitate its own propagation.
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Affiliation(s)
- Eun-Mee Park
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang 431-060, South Korea
| | - Lam N Nguyen
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang 431-060, South Korea
| | - Yun-Sook Lim
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang 431-060, South Korea
| | - Soon B Hwang
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang 431-060, South Korea.
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942
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Kim JH, Cox ME, Wasan KM. Effect of simvastatin on castration-resistant prostate cancer cells. Lipids Health Dis 2014; 13:56. [PMID: 24666612 PMCID: PMC3987159 DOI: 10.1186/1476-511x-13-56] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 03/11/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND In castration-resistant prostate cancer (CRPC), recent evidence has demonstrated the persistence of the intratumoral androgens. The multi-step androgen synthesis pathway originates from cholesterol, which can be obtained by cells from several major sources including intracellular synthesis through an enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR). The inhibition of this enzyme by the use of statins has been investigated in prostate cancer as a possible therapeutic target for blocking the de novo androgen synthesis resulting in decreased tumor growth. However, the effectiveness of statins in CRPC has not been investigated. METHODS Castration-resistant C4-2 and androgen-sensitive LNCaP cells were treated with Simvastatin for 48 hours. Dose-dependent responses to Simvastatin were analyzed using cell proliferation and cytotoxicity assays. Cellular growth curve was generated using haemocytometer. HMGCR activity was assessed using 14C-acetic acid detected by thin layer chromatography, and the protein expression was quantified using western blot analysis. Intracellular cholesterol and prostate specific antigen (PSA) levels were quantified using enzyme-linked immunosorbent assays (ELISA). RESULTS Significant decrease in cell viability and growth curve observed at 75 μM of Simvastatin compared to no treatment group in the castration-resistant C4-2 cells. HMGCR activity was significantly decreased up to 50% and 70% at 50 μM and 75 μM of Simvastatin respectively compared to the vehicle control in C4-2 cells. Simvastatin did not affect the protein expression. 80% decrease in the amount of total intracellular cholesterol levels was observed in 75 μM Simvastatin treatment group compared to vehicle control. PSA secretion levels were significantly reduced in the C4-2 cell line at 50 μM and 75 μM of Simvastatin compared to vehicle control. CONCLUSION The inhibition of HMGCR via Simvastatin lowered the viability of castration-resistant C4-2 cells. Simvastatin's ability to limit the endogenous supply of cholesterol contributes to the effects seen in cell viability.
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Affiliation(s)
| | | | - Kishor M Wasan
- Faculty of Pharmaceutical Sciences, University of British Columbia, 2405 Wesbrook Mall, Vancouver, British Columbia, Canada.
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943
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Abstract
BACKGROUND Understanding the physiology of pregnancy enables effective management of pregnancy complications that could otherwise be life threatening for both mother and fetus. A functional uterus (i) retains the fetus in utero during pregnancy without initiating stretch-induced contractions and (ii) is able to dilate the cervix and contract the myometrium at term to deliver the fetus. The onset of labour is associated with successful cervical remodelling and contraction of myometrium, arising from concomitant activation of uterine immune and endocrine systems. A large body of evidence suggests that actions of local steroid hormones may drive changes occurring in the uterine microenvironment at term. Although there have been a number of studies considering the potential role(s) played by progesterone and estrogen at the time of parturition, the bio-availability and effects of androgens during pregnancy have received less scrutiny. The aim of this review is to highlight potential roles of androgens in the biology of pregnancy and parturition. METHODS A review of published literature was performed to address (i) androgen concentrations, including biosynthesis and clearance, in maternal and fetal compartments throughout gestation, (ii) associations of androgen concentrations with adverse pregnancy outcomes, (iii) the role of androgens in the physiology of cervical remodelling and finally (iv) the role of androgens in the physiology of myometrial function including any impact on contractility. RESULTS Some, but not all, androgens increase throughout gestation in maternal circulation. The effects of this increase are not fully understood; however, evidence suggests that increased androgens might regulate key processes during pregnancy and parturition. For example, androgens are believed to be critical for cervical remodelling at term, in particular cervical ripening, via regulation of cervical collagen fibril organization. Additionally, a number of studies highlight potential roles for androgens in myometrial relaxation via non-genomic, AR-independent pathways critical for the pregnancy reaching term. Understanding of the molecular events leading to myometrial relaxation is an important step towards development of novel targeted tocolytic drugs. CONCLUSIONS The increase in androgen levels throughout gestation is likely to be important for establishment and maintenance of pregnancy and initiation of parturition. Further investigation of the underlying mechanisms of androgen action on cervical remodelling and myometrial contractility is needed. The insights gained may facilitate the development of new therapeutic approaches to manage pregnancy complications such as preterm birth.
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Affiliation(s)
- Sofia Makieva
- Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom and Tommy's Centre for Maternal and Fetal Health, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
| | - Philippa T K Saunders
- Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom and
| | - Jane E Norman
- Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom and Tommy's Centre for Maternal and Fetal Health, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
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944
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Dietary cholesterol supplementation to a plant-based diet suppresses the complete pathway of cholesterol synthesis and induces bile acid production in Atlantic salmon (Salmo salar L.). Br J Nutr 2014; 111:2089-103. [DOI: 10.1017/s0007114514000373] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Plants now supply more than 50 % of protein in Norwegian salmon aquafeeds. The inclusion of plant protein in aquafeeds may be associated with decreased lipid digestibility and cholesterol and bile salt levels, indicating that the replacement of fishmeal with plant protein could result in inadequate supplies of cholesterol in fish. A reduction in feed efficiency, fish growth and pathogen resistance is often observed in parallel to alterations in sterol metabolism. Previous studies have indicated that the negative effects induced by plant components can be attenuated when diets are supplemented with cholesterol. The present study evaluated the effects of dietary cholesterol supplementation (1·5 %) in Atlantic salmon fed a plant-based diet for 77 d. The weights of body, intestines and liver were recorded and blood, tissues, faeces, chyme and bile were sampled for the evaluation of effects on growth, nutrient utilisation and metabolism, and transcriptome and metabolite levels, with particular emphasis on sterol metabolism and organ structure and function. Cholesterol supplementation did not affect the growth or organ weights of Atlantic salmon, but seemed to promote the induction of cholesterol and plant sterol efflux in the intestine while suppressing sterol uptake. Cholesterol biosynthesis decreased correspondingly and conversion into bile acids increased. The marked effect of cholesterol supplementation on bile acid synthesis suggests that dietary cholesterol can be used to increase bile acid synthesis in fish. The present study clearly demonstrated how Atlantic salmon adjusted their metabolic functions in response to the dietary load of cholesterol. It has also expanded our understanding of sterol metabolism and turnover, adding to the existing, rather sparse, knowledge of these processes in fish.
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945
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Simmons C, Ingham V, Williams A, Bate C. Platelet-activating factor antagonists enhance intracellular degradation of amyloid-β42 in neurons via regulation of cholesterol ester hydrolases. Alzheimers Res Ther 2014; 6:15. [PMID: 24625058 PMCID: PMC4055000 DOI: 10.1186/alzrt245] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/19/2014] [Indexed: 12/26/2022]
Abstract
INTRODUCTION The progressive dementia that is characteristic of Alzheimer's disease is associated with the accumulation of amyloid-beta (Aβ) peptides in extracellular plaques and within neurons. Aβ peptides are targeted to cholesterol-rich membrane micro-domains called lipid rafts. Observations that many raft proteins undertake recycling pathways that avoid the lysosomes suggest that the accumulation of Aβ in neurons may be related to Aβ targeting lipid rafts. Here we tested the hypothesis that the degradation of Aβ by neurons could be increased by drugs affecting raft formation. METHODS Primary neurons were incubated with soluble Aβ preparations. The amounts of Aβ42 in neurons or specific cellular compartments were measured by enzyme-linked immunosorbent assay. The effects of drugs on the degradation of Aβ42 were studied. RESULTS Aβ42 was targeted to detergent-resistant, low-density membranes (lipid rafts), trafficked via a pathway that avoided the lysosomes, and was slowly degraded by neurons (half-life was greater than 5 days). The metabolism of Aβ42 was sensitive to pharmacological manipulation. In neurons treated with the cholesterol synthesis inhibitor squalestatin, less Aβ42 was found within rafts, greater amounts of Aβ42 were found in lysosomes, and the half-life of Aβ42 was reduced to less than 24 hours. Treatment with phospholipase A2 inhibitors or platelet-activating factor (PAF) antagonists had the same effects on Aβ42 metabolism in neurons as squalestatin. PAF receptors were concentrated in the endoplasmic reticulum (ER) along with enzymes that constitute the cholesterol ester cycle. The addition of PAF to ER membranes triggered activation of cholesterol ester hydrolases and the release of cholesterol from stores of cholesterol esters. An inhibitor of cholesterol ester hydrolases (diethylumbelliferyl phosphate) also increased the degradation of Aβ42 in neurons. CONCLUSIONS We conclude that the targeting of Aβ42 to rafts in normal cells is a factor that affects its degradation. Critically, pharmacological manipulation of neurons can significantly increase Aβ42 degradation. These results are consistent with the hypothesis that the Aβ-induced production of PAF controls a cholesterol-sensitive pathway that affects the cellular localization and hence the fate of Aβ42 in neurons.
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Affiliation(s)
- Charlotte Simmons
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK
| | - Victoria Ingham
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK
| | - Alun Williams
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK
| | - Clive Bate
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK
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946
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Sahoo S, Aurich MK, Jonsson JJ, Thiele I. Membrane transporters in a human genome-scale metabolic knowledgebase and their implications for disease. Front Physiol 2014; 5:91. [PMID: 24653705 PMCID: PMC3949408 DOI: 10.3389/fphys.2014.00091] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 02/17/2014] [Indexed: 01/18/2023] Open
Abstract
Membrane transporters enable efficient cellular metabolism, aid in nutrient sensing, and have been associated with various diseases, such as obesity and cancer. Genome-scale metabolic network reconstructions capture genomic, physiological, and biochemical knowledge of a target organism, along with a detailed representation of the cellular metabolite transport mechanisms. Since the first reconstruction of human metabolism, Recon 1, published in 2007, progress has been made in the field of metabolite transport. Recently, we published an updated reconstruction, Recon 2, which significantly improved the metabolic coverage and functionality. Human metabolic reconstructions have been used to investigate the role of metabolism in disease and to predict biomarkers and drug targets. Given the importance of cellular transport systems in understanding human metabolism in health and disease, we analyzed the coverage of transport systems for various metabolite classes in Recon 2. We will review the current knowledge on transporters (i.e., their preferred substrates, transport mechanisms, metabolic relevance, and disease association for each metabolite class). We will assess missing coverage and propose modifications and additions through a transport module that is functional when combined with Recon 2. This information will be valuable for further refinements. These data will also provide starting points for further experiments by highlighting areas of incomplete knowledge. This review represents the first comprehensive overview of the transporters involved in central metabolism and their transport mechanisms, thus serving as a compendium of metabolite transporters specific for human metabolic reconstructions.
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Affiliation(s)
- Swagatika Sahoo
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Maike K Aurich
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Jon J Jonsson
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Iceland Reykjavik, Iceland ; Department of Genetics and Molecular Medicine, Landspitali, National University Hospital of Iceland Reykjavik, Iceland
| | - Ines Thiele
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
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947
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Amini-Bavil-Olyaee S, Choi YJ, Lee JH, Shi M, Huang IC, Farzan M, Jung JU. The antiviral effector IFITM3 disrupts intracellular cholesterol homeostasis to block viral entry. Cell Host Microbe 2014; 13:452-64. [PMID: 23601107 PMCID: PMC3646482 DOI: 10.1016/j.chom.2013.03.006] [Citation(s) in RCA: 267] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/04/2012] [Accepted: 03/19/2013] [Indexed: 12/21/2022]
Abstract
Vesicle-membrane-protein-associated protein A (VAPA) and oxysterol-binding protein (OSBP) regulate intracellular cholesterol homeostasis, which is required for many virus infections. During entry, viruses or virus-containing vesicles can fuse with endosomal membranes to mediate the cytosolic release of virions, and alterations in endosomal cholesterol can inhibit this invasion step. We show that the antiviral effector protein interferon-inducible transmembrane protein 3 (IFITM3) interacts with VAPA and prevents its association with OSBP, thereby disrupting intracellular cholesterol homeostasis and inhibiting viral entry. By altering VAPA-OSBP function, IFITM3 induces a marked accumulation of cholesterol in multivesicular bodies and late endosomes, which inhibits the fusion of intraluminal virion-containing vesicles with endosomal membranes and thereby blocks virus release into the cytosol. Consequently, ectopic expression or depletion of the VAPA gene profoundly affects IFITM3-mediated inhibition of viral entry. Thus, IFITM3 disrupts intracellular cholesterol homeostasis to block viral entry, further underscoring the importance of cholesterol in virus infection.
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Affiliation(s)
- Samad Amini-Bavil-Olyaee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, 1450 Biggy Street, Los Angeles, CA 90033, USA
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948
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Yue S, Li J, Lee SY, Lee HJ, Shao T, Song B, Cheng L, Masterson TA, Liu X, Ratliff TL, Cheng JX. Cholesteryl ester accumulation induced by PTEN loss and PI3K/AKT activation underlies human prostate cancer aggressiveness. Cell Metab 2014; 19:393-406. [PMID: 24606897 PMCID: PMC3969850 DOI: 10.1016/j.cmet.2014.01.019] [Citation(s) in RCA: 617] [Impact Index Per Article: 61.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/24/2013] [Accepted: 01/23/2014] [Indexed: 01/02/2023]
Abstract
Altered lipid metabolism is increasingly recognized as a signature of cancer cells. Enabled by label-free Raman spectromicroscopy, we performed quantitative analysis of lipogenesis at single-cell level in human patient cancerous tissues. Our imaging data revealed an unexpected, aberrant accumulation of esterified cholesterol in lipid droplets of high-grade prostate cancer and metastases. Biochemical study showed that such cholesteryl ester accumulation was a consequence of loss of tumor suppressor PTEN and subsequent activation of PI3K/AKT pathway in prostate cancer cells. Furthermore, we found that such accumulation arose from significantly enhanced uptake of exogenous lipoproteins and required cholesterol esterification. Depletion of cholesteryl ester storage significantly reduced cancer proliferation, impaired cancer invasion capability, and suppressed tumor growth in mouse xenograft models with negligible toxicity. These findings open opportunities for diagnosing and treating prostate cancer by targeting the altered cholesterol metabolism.
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Affiliation(s)
- Shuhua Yue
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Junjie Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Seung-Young Lee
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Hyeon Jeong Lee
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - Tian Shao
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Liang Cheng
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Timothy A Masterson
- Department of Urology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Timothy L Ratliff
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA; Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA; Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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949
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Ontsouka EC, Albrecht C. Cholesterol transport and regulation in the mammary gland. J Mammary Gland Biol Neoplasia 2014; 19:43-58. [PMID: 24510467 DOI: 10.1007/s10911-014-9316-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 01/22/2014] [Indexed: 01/28/2023] Open
Abstract
The milk-producing alveolar epithelial cells secrete milk that remains after birth the principal source of nutrients for neonates. Milk secretion and composition are highly regulated processes via integrated actions of hormones and local factors which involve specific receptors and downstream signal transduction pathways. Overall milk composition is similar among mammalian species, although the content of individual constituents such as lipids may significantly differ from one species to another. The milk lipid fraction is essentially composed of triglycerides, which represent more than 95 % of the total lipids in human and commercialized bovine milk. Though sterols, including cholesterol, which is the major milk sterol, represent less than 0.5 % of the total milk lipid fraction, they are of key importance for several biological processes. Cholesterol is required for the formation of biological membranes especially in rapidly growing organisms, and for the synthesis of sterol-based compounds. Cholesterol found in milk originates predominantly from blood uptake and, to a certain extent, from local synthesis in the mammary tissue. The present review summarizes current knowledge on cellular mechanisms and regulatory processes determining intra- and transcellular cholesterol transport in the mammary gland. Cholesterol exchanges between the blood, the mammary alveolar cells and the milk, and the likely role of active cholesterol transporters in these processes are discussed. In this context, the hormonal regulation and signal transduction pathways promoting active cholesterol transport as well as potential regulatory crosstalks are highlighted.
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Affiliation(s)
- Edgar C Ontsouka
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, Buehlstrasse 28, 3012, Bern, Switzerland
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950
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Are hypertriglyceridemia and low HDL causal factors in the development of insulin resistance? Atherosclerosis 2014; 233:130-8. [DOI: 10.1016/j.atherosclerosis.2013.12.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 02/07/2023]
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