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Comorbidities of HIV infection: role of Nef-induced impairment of cholesterol metabolism and lipid raft functionality.
Sviridov, D, Mukhamedova, N, Makarov, AA, Adzhubei, A, Bukrinsky, M
AIDS (London, England). 2020;(1):1-13
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Abstract
: Combination antiretroviral therapy has dramatically changed the outcome of HIV infection, turning it from a death sentence to a manageable chronic disease. However, comorbidities accompanying HIV infection, such as metabolic and cardio-vascular diseases, as well as cognitive impairment, persist despite successful virus control by combination antiretroviral therapy and pose considerable challenges to clinical management of people living with HIV. These comorbidities involve a number of pathological processes affecting a variety of different tissues and cells, making it challenging to identify a common cause(s) that would link these different diseases to HIV infection. In this article, we will present evidence that impairment of cellular cholesterol metabolism may be a common factor driving pathogenesis of HIV-associated comorbidities. Potential implications for therapeutic approaches are discussed.
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G Protein-Coupled Estrogen Receptor, GPER1, Offers a Novel Target for the Treatment of Digestive Diseases.
DeLeon, C, Wang, DQ, Arnatt, CK
Frontiers in endocrinology. 2020;:578536
Abstract
There are gender differences between men and women in many physiological functions and diseases, which indicates that female sex hormones may be important. Traditionally, estrogen exerts its biological activities by activating two classical nuclear estrogen receptors, ESR1 and ESR2. However, the roles of estrogen in the regulation of physiological functions and the pathogenesis of diseases become more complicated with the identification of the G protein-coupled estrogen receptor (GPER1). Although many GPER1-specific ligands have been developed, the therapeutic mechanisms of exclusively targeting GPER1 are not yet well understood. Translational applications and clinical trial efforts for the identified GPER1 ligands have been focused primarily on the reproductive, cardiovascular, nervous, endocrine, and immune systems. More recently, research found that GPER1 may play an important role in regulating the digestive system. Cholesterol gallstone disease, a major biliary disease, has a higher prevalence in women than in men worldwide. Emerging evidence implies that GPER1 could play an important role, independent of the classical ESR1, in the pathophysiology of cholesterol gallstones in women. This review discusses the complex signaling pathways of three estrogen receptors, highlights the development of GPER1-specific ligands, and summarizes the latest advances in the role of GPER1 in the pathogenesis of gallstone formation.
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Dysregulated Brain Cholesterol Metabolism Is Linked to Neuroinflammation in Huntington's Disease.
González-Guevara, E, Cárdenas, G, Pérez-Severiano, F, Martínez-Lazcano, JC
Movement disorders : official journal of the Movement Disorder Society. 2020;(7):1113-1127
Abstract
Huntington's disease is an autosomal-dominant, neurodegenerative disorder caused by a CAG repeat expansion in exon-1 of the huntingtin gene. Alterations in cholesterol metabolism and distribution have been reported in Huntington's disease, including abnormal interactions between mutant huntingtin and sterol regulatory element-binding proteins, decreased levels of apolipoprotein E/cholesterol/low-density lipoprotein receptor complexes, and alterations in the synthesis of ATP-binding cassette transporter A1. Plasma levels of 24S-hydroxycholestrol, a key intermediary in cholesterol metabolism and a possible marker in neurodegenerative diseases, decreased proportionally to the degree of caudate nucleus atrophy. The interaction of mutant huntingtin with sterol regulatory element-binding proteins is of particular interest given that sterol regulatory element-binding proteins play a dual role: They take part in lipid and cholesterol metabolism, but also in the inflammatory response that induces immune cell migration as well as toxic effects, particularly in astrocytes. This work summarizes current evidence on the metabolic and immune implications of sterol regulatory element-binding protein dysregulation in Huntington's disease, highlighting the potential use of drugs that modulate these alterations. © 2020 International Parkinson and Movement Disorder Society.
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Cardiovascular Risk Assessment and Therapeutic Implications in Rheumatoid Arthritis.
Halacoglu, J, Shea, LA
Journal of cardiovascular translational research. 2020;(5):878-890
Abstract
Patients with rheumatoid arthritis (RA) suffer from a magnitude of excess cardiovascular risk. A paradoxical lipid pattern has been observed in rheumatoid arthritis patients where low levels of total cholesterol and low-density lipoprotein are associated with a higher risk of cardiovascular disease. This paper aims to break down the evidence explaining why patients with low to normal LDL, and total cholesterol have such excess cardiovascular risk. A component of the enhanced cardiovascular risk is systemic inflammation and the subsequent pro-atherogenic dyslipidemia patterns. Due to this "lipid paradox," current risk algorithms and guidelines designed for the general population may underestimate cardiovascular risk in patients with rheumatoid arthritis. The purpose of this paper is to critically evaluate some of the discrepancies and layers of cardiovascular risk in RA patients, the role RA medication may have in mitigating or increasing cardiovascular risk, and the possible role of statin therapy.
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5.
The desmosome as a model for lipid raft driven membrane domain organization.
Zimmer, SE, Kowalczyk, AP
Biochimica et biophysica acta. Biomembranes. 2020;(9):183329
Abstract
Desmosomes are cadherin-based adhesion structures that mechanically couple the intermediate filament cytoskeleton of adjacent cells to confer mechanical stress resistance to tissues. We have recently described desmosomes as mesoscale lipid raft membrane domains that depend on raft dynamics for assembly, function, and disassembly. Lipid raft microdomains are regions of the plasma membrane enriched in sphingolipids and cholesterol. These domains participate in membrane domain heterogeneity, signaling and membrane trafficking. Cellular structures known to be dependent on raft dynamics include the post-synaptic density in neurons, the immunological synapse, and intercellular junctions, including desmosomes. In this review, we discuss the current state of the desmosome field and put forward new hypotheses for the role of lipid rafts in desmosome adhesion, signaling and epidermal homeostasis. Furthermore, we propose that differential lipid raft affinity of intercellular junction proteins is a central driving force in the organization of the epithelial apical junctional complex.
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New agents to reduce cholesterol levels: implications for nephrologists.
Del Vecchio, L, Baragetti, I, Locatelli, F
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2020;(2):213-218
Abstract
Statins and ezetimibe effectively reduce the burden of cardiovascular (CV) disease in patients with chronic kidney disease (CKD). Unfortunately, many subjects still die or have CV events despite cholesterol-lowering therapy. This is particularly true in patients with more advanced CKD. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that induces the degradation of the low-density lipoprotein receptor by targeting it for lysosomal destruction. Its inhibition causes a dramatic fall in cholesterol levels on top of maximized statin therapy. This goal is obtained with different therapeutic approaches, spanning from monoclonal antibodies to non sense oligonucleotides and silencing RNA (siRNA). Two human, monoclonal antibodies are approved for clinical use; they are still very expensive. Both agents significantly lower cholesterol levels. Evolocumab and alirocumab reduce significantly the risk for CV disease without relevant safety issues. Inclisiran is an siRNA molecule that produces PCSK9-specific RNA silencing. Data from a Phase II study showed significant cholesterol-lowering efficacy. The experience accumulated so far is limited in the CKD population. PCSK9 inhibition also has the potential to reduce the burden of CV in this subset by obtaining a much greater decrease in serum cholesterol compared with statin therapy or ezetimibe. Doubts exist that this approach will improve the outcome of dialysis patients, in whom vascular calcifications predominate.
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Sterol synthesis pathway inhibition as a target for cancer treatment.
Feltrin, S, Ravera, F, Traversone, N, Ferrando, L, Bedognetti, D, Ballestrero, A, Zoppoli, G
Cancer letters. 2020;:19-30
Abstract
Sterol synthesis is a highly complex and integrated pathway in mammals. In the present review, we briefly summarize the main steps of this pathway, especially concerning its main rate-limiting enzymes, HMG-CoA reductase (HMGCR) and squalene epoxidase (SQLE), in relation with cancer. We focus on studies reporting key findings linking cholesterol with cancer. The inhibition of HMGCR and SQLE to prevent and inhibit cancer are reviewed. Finally, a pan-cancer review of publicly available data on genomic aberrations in the main enzymes involved in sterol biosynthesis and their transcription factors is reported, providing hitherto unexplored findings that may be the subject of future research in cancer metabolomics and tumor targeted treatment.
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8.
Cholesterol and beyond - The role of the mevalonate pathway in cancer biology.
Göbel, A, Rauner, M, Hofbauer, LC, Rachner, TD
Biochimica et biophysica acta. Reviews on cancer. 2020;(2):188351
Abstract
Cancer is a multifaceted global disease. Transformation of a normal to a malignant cell takes several steps, including somatic mutations, epigenetic alterations, metabolic reprogramming and loss of cell growth control. Recently, the mevalonate pathway has emerged as a crucial regulator of tumor biology and a potential therapeutic target. This pathway controls cholesterol production and posttranslational modifications of Rho-GTPases, both of which are linked to several key steps of tumor progression. Inhibitors of the mevalonate pathway induce pleiotropic antitumor-effects in several human malignancies, identifying the pathway as an attractive candidate for novel therapies. In this review, we will provide an overview about the role and regulation of the mevalonate pathway in certain aspects of cancer initiation and progression and its potential for therapeutic intervention in oncology.
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9.
Cholesterol metabolism: New functions and therapeutic approaches in cancer.
Xu, H, Zhou, S, Tang, Q, Xia, H, Bi, F
Biochimica et biophysica acta. Reviews on cancer. 2020;(1):188394
Abstract
Cholesterol and its metabolites (precursors and derivatives) play an important role in cancer. In recent years, numerous studies have reported the functions of cholesterol metabolism in the regulation of tumor biological processes, especially oncogenic signaling pathways, ferroptosis, and tumor microenvironment. Preclinical studies have over the years indicated the inhibitory effects of blocking cholesterol synthesis and uptake on tumor formation and growth. Besides, some new cholesterol metabolic molecules such as SOAT1, SQLE, and NPC1 have recently emerged as promising drug targets for cancer treatment. Here, we systematically review the roles of cholesterol and its metabolites, and the latest advances in cancer therapy targeting cholesterol metabolism.
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10.
Enantiomers of phospholipids and cholesterol: A key to decipher lipid-lipid interplay in membrane.
Hanashima, S, Yano, Y, Murata, M
Chirality. 2020;(3):282-298
Abstract
Most phospholipids constituting biological membranes are chiral molecules with a hydrophilic head group and hydrophobic alkyl chains, rendering biphasic property characteristic of membrane lipids. Some lipids assemble into small domains via chirality-dependent homophilic and heterophilic interactions, the latter of which sometimes include cholesterol to form lipid rafts and other microdomains. On the other hand, lipid mediators and hormones derived from chiral lipids are recognized by specific membrane or nuclear receptors to induce downstream signaling. It is crucial to clarify the physicochemical properties of the lipid self-assembly for the study of the functions and behavior of biological membranes, which often become elusive due to effects of membrane proteins and other biological events. Three major lipids with different skeletal structures were discussed: sphingolipids including ceramides, phosphoglycerolipids, and cholesterol. The physicochemical properties of membranes and physiological functions of lipid enantiomers and diastereomers were described in comparison to natural lipids. When each enantiomer formed a self-assembly or interacted with achiral lipids, both lipid enantiomers exhibited identical membrane physicochemical properties, while when the enantiomer interacted with chiral lipids or with the opposite enantiomer, mixed membranes exhibited different properties. For example, racemic membranes comprising native sphingomyelin and its antipode exhibited phase segregation due to their strong homophilic interactions. Therefore, lipid enantiomers and diastereomers can be good probes to investigate stereospecific lipid-lipid and lipid-protein interactions occurring in biological membranes.