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Volume 46, Issue 1
Displaying 1-9 of 9 articles from this issue
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Special Topic : Amyloid Formation and Membranes
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Maho Yagi-Utsumi, Koichi Kato2021 Volume 46 Issue 1 Pages 2-6
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSNeurodegenerative diseases are caused by the abnormal assembly of toxic proteins, such as amyloid β (A β) in Alzheimer’s disease. Mounting evidence suggests that the morphology of amyloid fibrils is strongly influenced by solution conditions, including protein concentration, ionic strength, pH, temperature, pressure, and gravity. Amyloid formation occurs in a heterogeneous multimolecular crowding environment, typified by the surface of the cell membrane. The aggregation of various amyloidogenic proteins, including A β, can be significantly increased on membranes containing glycolipids, which induce dynamic conformational changes that are crucial for amyloid fibril formation. However, because of varying complexity, the molecular basis of environmental impact on Aβ fibrilization remains to be clarified. Therefore, for deeper understanding of the molecular mechanism behind the amyloid formation, it is necessary to characterize dynamic structural changes and interactions of Aβ molecules in complex microenvironments. Here, we have reviewed structural studies on Aβ assembly considering environmental factors, highlighting NMR studies of A β in glycolipid clusters.View full abstractDownload PDF (823K) -
Teruhiko Matsubara, Toshinori Sato2021 Volume 46 Issue 1 Pages 7-11
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSThe assembly of amyloid β protein (Aβ) on membrane microdomains in presynaptic neuronal membranes is involved in the onset of Alzheimer’s disease. The Aβ– sensitive ganglioside nanocluster (ASIGN) was identified by the surface topography of the lipid bilayers composed of brain–extracted lipids. Our results indicate that the ganglioside clustering is responsible for the Aβ– assemblies on the neuronal membranes.View full abstractDownload PDF (919K) -
Keisuke Ikeda2021 Volume 46 Issue 1 Pages 12-18
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSConversion of non–toxic soluble amyloid –β protein (Aβ) into cytotoxic aggregates such as oligomers and amyloid fibrils is a critical step in the development of Alzheimer’s disease. A growing body of evidence is accumulating to show that biological membrane vesicles, both inside and outside cells, are involved in multiple processes, including Aβ production, metabolism, aggregation, transport, and clearance. Here, we review the biological studies on the interaction between Aβ and membrane vesicles such as endosomes, multivesicular bodies (MVBs), and exosomes in the pathological brains, animal models, and cultured cells. Subsequently, biochemical and physicochemical studies on the Aβ– lipid interactions that underlie molecular mechanisms of Aβ– vesicle association will be discussed. In addition, a study focusing on the high membrane curvature of intraluminal vesicles of MVBs and exosomes due to their small particle size will be presented. We show that high membrane curvature promotes Aβ binding, structural changes, and fibrillation on lipid bilayer surfaces.View full abstractDownload PDF (842K) -
Eri Chatani2021 Volume 46 Issue 1 Pages 19-24
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSAmyloid fibrils generally have a cross –β structure, in which β– strands are stacked in the axial direction of the fibril. Probably because of this periodic structure, the formation of amyloid fibrils is similar to that of crystals, and the nucleation process is observed in early stages, acting as a rate–determining step. This article outlines the basic properties of amyloid fibril nucleation in the light of the nucleation theory proposed for crystallization. I also discuss how amyloid nucleation is affected at a lipid membrane interface in order to understand the mechanism of amyloid fibril formation in biological systems.View full abstractDownload PDF (817K) -
Chiharu Mizuguchi, Takashi Ohgita, Hiroyuki Saito2021 Volume 46 Issue 1 Pages 25-31
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSLipid membranes are known to influence the folding, aggregation, and fibril formation of a variety of amyloidogenic proteins. In some natively unstructured amylodogenic proteins such as α– synuclein and islet amyloid peptide, the formation of partially α– helical conformations upon membrane binding promotes the aggregation of proteins through exposure of highly amyloidogenic regions. We recently demonstrated that a G26R mutation, the first amyloidogenic mutation found in apolipoprotein A–I (apoA–I), facilitates aggregation and fibril formation of the N–terminal 1–83 fragment of apoA–I on lipid membranes through a partial destabilization of α– helical conformation. Here, we have reviewed the molecular mechanism of membrane-mediated aggregation and fibril formation of the amyloidogenic N–terminal fragment of apoA–I. We also briefly introduce the membrane–mediated aggregation behavior of α– synuclein that has similar lipid-binding property to apoA–I.View full abstractDownload PDF (1010K) -
Kazuma Yasuhara2021 Volume 46 Issue 1 Pages 32-37
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSThe lipid membrane is known to provide a unique reaction field for the assembly of amyloidogenic proteins. Recently, lipid bilayer nanodisc has attracted attention as a novel model membrane system to understand the interaction of proteins and peptides with membranes. In this article, we will feature the use of lipid bilayer nanodisc for the analysis of amyloidogenic proteins that provide new aspects for their action mechanism.View full abstractDownload PDF (888K)
Review Article
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Yusuke Nakatsu, Tomoichiro Asano2021 Volume 46 Issue 1 Pages 38-43
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSGlucose is a main energy source for ATP production and its effective utilization is important to maintain homeostasis. Although glucose is filtrated in glomerulus, sodium glucose co–transporter 1/2 (SGLT1/2) in the renal tubules reabsorbs it. SGLT2 selectively expresses in the proximal tubules and reabsorbs a large fraction of glucose, while SGLT1 exists in the kidney and small intestine to take up both glucose and galactose. Accordingly, SGLT2 inhibition could block glucose reabsorption and, indeed, SGLT2 inhibitors show the expected effects. Importantly, human SGLT2 deficiency or SGLT2 knockout mice show no remarkable phenotypes except renal glycosuria, supporting that SGLT2 inhibitors could be relatively safe. In addition, recent studies reveal that treatment with SGLT2 inhibitors improves a variety of metabolic syndromes, such as nonalcoholic steatosis, atherosclerosis and diabetic nephropathy. In this review, we introduce the characterization of SGLT2 and the effect of SGLT2 inhibitors on metabolic syndromes.View full abstractDownload PDF (1185K)
Original Contribution
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Toshio Sano, Shunsuke Yamamoto, Itsuki Kokubo, Naoki Murakami, Kenichi ...2021 Volume 46 Issue 1 Pages 44-52
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL FREE ACCESSMembrane properties such as porosity and surface morphology significantly affect fouling in membrane bioreactors (MBRs). Amphiphilic Pluronic block–copolymers have attracted attention in recent years as their use during membrane preparation has resulted in improved membrane properties. This study focused on establishing a technique to improve membrane properties by adding Pluronic TR–702 to prepare a chlorinated poly(vinyl chloride) (CPVC) flat–sheet membrane suitable for use in an MBR. Deterioration of Pluronic TR–702 was expected during long–term MBR applications. Therefore, Pluronic TR–702 was removed from the membranes prior to evaluation. The influence of the additive on the membrane thickness, pure water permeability, pore size and distribution, surface morphology, and surface porosity was investigated. Excessive addition of Pluronic TR–702 to the dope solution led to the preparation of membranes with larger pore sizes that were unsuitable for MBR. On the other hand, appropriate addition increased the pore size and thickness of the membranes and decreased the surface porosity with increasing additive content. When the concentration of Pluronic TR–702 was 50 wt/wt%, the membrane with the suitable pore size for the use in MBR was prepared. This method is a useful technique for improving the properties of membranes used for MBRs.View full abstractDownload PDF (694K)
Products Spotlight
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Hiro Yoshikawa2021 Volume 46 Issue 1 Pages 53-55
Published: 2021
Released on J-STAGE: January 30, 2021
JOURNAL RESTRICTED ACCESSRO chemicals play a key role to optimize the operational cost of RO systems by preventing various kinds of fouling. ORGANO has some unique RO chemicals such as biocides or antiscalants. In this article, the details of our chemicals, such as its performances or field data, are presented.View full abstractDownload PDF (803K)
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