Lipids And Cellular Membranes In Amyloid Diseases

Addressing one of the biggest riddles in current molecular cell biology, this ground-breaking monograph builds the case for the crucial involvement of lipids and membranes in the formation of amyloid deposits. Tying together recent knowledge from in vitro and in vivo studes, and built on a sound biophysical and biochemical foundation, this overview brings the reader up to date with current models of the interplay between membranes and amyloid formation. Required reading for any researcher interested in amyloid formation and amyloid toxicity, and possible avenues for the prevention or treatment of neurodegenerative disorders. From the contents: * Interactions of Alpha-Synuclein with Lipids * Interaction of hIAPP and its Precursors with Membranes * Amyloid Polymorphisms: Structural Basis and Significance in Biology and Molecular Medicine * The Role of Lipid Rafts in Alzheimer's Disease * Alzheimer's Disease as a Membrane-Associated Enzymopathy of Beta-Amyloid Precursor Protein (APP) Secretases * Impaired Regulation of Glutamate Receptor Channels and Signaling Molecules by Beta-Amyloid in Alzheimer's Disease * Membrane Changes in BSE and Scrapie * Experimental Approaches and Technical Challenges for Studying Amyloid-Membrane Interactions and more

​Protein conversion from a water-soluble native conformation to the insoluble aggregates and fibrils, which can deposit in amyloid plaques, underlies more than 20 human diseases, representing a major public health problem and a scientific challenge. Such a conversion is called protein misfolding. Protein misfolding can also involve errors in the topology of the folded proteins and their assembly in lipid membranes. Lipids are found in nearly all amyloid deposits in vivo, and can critically influence protein misfolding in vitro and in vivo in many different ways. This book focuses on recent advances in our understanding of the role of lipids in modulating the misfolding of various proteins. The main emphasis is on the basic biophysical studies that address molecular basis of protein misfolding and amyloid formation, and the role of lipids in this complex process.

Amyloidosis is a group of protein misfolding diseases caused by tissue deposition of fibrillary protein aggregates termed amyloid. Amyloid A (AA) amyloidosis is a systemic form of amyloidosis that occurs as a complication of chronic inflammatory diseases, such as rheumatoid arthritis, familial Mediterranean fever and chronic infections, such as tuberculosis. AA amyloid is derived from the precursor protein serum amyloid A and is deposited in several organs preferably kidneys, liver and spleen. AA amyloidosis can be induced in mice by long standing inflammatory stimulation and concurrent administration of tissue extracts of AA amyloid, referred to as amyloid enhancing factor (AEF), reduces the time for amyloid deposition in the marginal zone of the spleen from 5 weeks to 2 days. The general aim of this thesis was to investigate the mechanisms involved in the development of AA amyloid in the mouse model of AA amyloidosis. Amyloid was induced in inflamed mice by injection of AEF and amyloid toxicity to splenic macrophages was investigated. We found that the marginal zone macrophages were very sensitive to amyloid formation and increasing amyloid load caused progressive depletion of these cells, whereas red pulp macrophages and metallophilic marginal zone macrophages appeared unaffected. To clarify the role of splenic macrophages in amyloidogenesis, macrophages were depleted by clodronate containing liposomes. We displayed that in the absence of splenic macrophages, especially marginal zone macrophages, amyloid formation was delayed implying a crucial role of macrophages in amyloid formation. The effect of lipid membranes on amyloid formation was studied and we showed that liposomes exhibited an amyloidogenic effect in inflamed mice although not as powerful as AEF. Following the fate of the liposomes, we showed that liposomes were rapidly cleared by uptake in the spleen and liver and colocalized with lysosomes. A tentative mechanism might be that accumulation of liposomes in lysosomes interfere with the SAA degradation process facilitating amyloid formation. Finally the conformational properties of two AEF (AEF1 and AEF2) preparations were studied using conformation sensitive luminescent-conjugated oligothiophenes (LCOs). We found that AEF1 and AEF2 displayed significantly different ultrastructure as well as conformation and consequently induced different cytotoxicity in vitro. Inducing amyloid formation in inflamed mice by AEF1 and AEF2 revealed that the polymorph of the amyloid aggregates was replicated in vivo. In summary, the results obtained in this thesis indicate an important role for macrophages for the formation of amyloid. The existence of amyloid strains has long been an in vitro finding, but the finding that AEF ultrastructure drives the morphology of newly formed amyloid in vivo opens up for new studies that can help us to understand the formation of homologous and heterologous fibrils. Thus, the fundamental mechanisms of various amyloid diseases are similar and the results presented in the thesis can increase the understanding of other amyloid diseases.

The lipids of cellular membranes not only serve roles in controlling the structure and fluidity of the membrane, but are increasingly recognized for their roles as signalling molecules and modifiers of membrane protein function. Recent studies described in this volume reveal striking changes in membrane lipids during aging and in age-related diseases such as cancer, cardiovascular disease and neurodegenerative disorders. Lipids including inositol phospholipids, cholesterol, sphingolipids and ceramides play important roles in signalling cellular responses to stress and specific stimuli such as growth factors, cytokines and neurotransmitters. One or more of these lipid mediators has been linked to the pathogenesis of age-related diseases. This book provides a comprehensive review of specific membrane lipid mediators and their roles in aging and age-related disease.

Lipids are the most abundant organic compounds found in the brain, accounting for up to 50% of its dry weight. The brain lipidome includes several thousands of distinct biochemical structures whose expression may greatly vary according to age, gender, brain region, cell type, as well as subcellular localization. In synaptic membranes, brain lipids specifically interact with neurotransmitter receptors and control their activity. Moreover, brain lipids play a key role in the generation and neurotoxicity of amyloidogenic proteins involved in the pathophysiology of neurological diseases. The aim of this book is to provide for the first time a comprehensive overview of brain lipid structures, and to explain the roles of these lipids in synaptic function, and in neurodegenerative diseases, including Alzheimer’s, Creutzfeldt-Jakob’s and Parkinson’s. To conclude the book, the authors present new ideas that can drive innovative therapeutic strategies based on the knowledge of the role of lipids in brain disorders. Written to provide a "hands-on" approach for readers Biochemical structures explained with molecular models, and molecular mechanisms explained with simple drawings Step-by-step guide to memorize and draw lipid structures Each chapter features a content summary, up-to-date references for additional study, and a key experiment with an explanation of the technique

Human Cell Membrane Therapy explores the theoretical and practical dimensions of improving service provision on majority of the diseases caused by cell damage. This readable and well-structured book is based on the reviews of current scientific publications on cellular membranes, its chemical structure and changes in many diseases.

Of the many special roles played by proteolytic enzymes in immune reactions, this book addresses different aspects of membrane peptidases, signal transduction via ligation of membrane peptidases (especially of dipeptidyl peptidase IV/CD26 and aminopeptidase N/CD13), and regulation of membrane peptidases in vivo and in vitro. A number of newly discovered peptidases (including cathepsin F, W and X, carboxypeptidase X, attractin) are described, with special emphasis given to the role of peptidases in immune and defense reactions and in the pathogenesis of inflammatory and other diseases, including rheumatoid arthritis, pancreatitis, multiple sclerosis, Alzheimer's disease and tumours of various origins. The focus on the involvement of a selection of proteolytic enzymes in immune reactions and diseases is a unique feature of this multifaceted work , which combines biochemical, immunological and clinical research reports with literary reviews of the field.