Molecular Chaperones

Molecular chaperones are involved in a wide variety of essential cellular processes in living cells. A subset of molecular chaperones have been initially described as heat shock proteins protecting cells from stress damage by keeping cellular proteins in a folding competent state and preventing them from irreversible aggregation. Later it became obvious that molecular chaperones are also expressed constitutively in the cell and are involved in complex processes such as protein synthesis, intracellular protein transport, post-translational modification and secretion of proteins as well as receptor signalling. Hence, it is not surprising that molecular chaperones are implicated in the pathogenesis of many relevant diseases and could be regarded as potential pharmacological targets. Starting with the analysis of the mode of action of chaperones at the molecular, cellular and organismic level, this book will then describe specific aspects where modulation of chaperone action could be of pharmacological and therapeutic interest.

In this text, leading experts synthesise our body of knowledge , and the reader gains not only a fuller understanding of the roles of chaperones in the context of cellular processes, but also an insight into the nature of these proteins.

The precise shape of a protein is a crucial factor in its function. How do proteins become folded into the right conformation? Molecular chaperones and protein folding catalysts bind to developing polypeptides in the cytoplasm and ensure correct folding and transport. This Guidebook catalogues the latest information on nearly 200 of these molecules, including the important class of heat shock proteins; each entry is written by leading researchers in the field.

This book reviews understanding of the biological roles of extracellular molecular chaperones. It provides an overview of the structure and function of molecular chaperones, their role in the cellular response to stress and their disposition within the cell. It also questions the basic paradigm of molecular chaperone biology - that these proteins are first and foremost protein-folding molecules. Paradigms of protein secretion are reviewed and the evolving concept of proteins (such as molecular chaperones) as multi-functional molecules for which the term 'moonlighting proteins' has been introduced is discussed. The role of exogenous molecular chaperones as cell regulators is examined and the physiological and pathophysiological role that molecular chaperones play is described. In the final section, the potential therapeutic use of molecular chaperones is described and the final chapter asks the question - what does the future hold for the extracellular biology of molecular chaperones?

The heat shock, or cell stress, response was first identified in the polytene chromosomes of Drosophila. This was later related to the appearance of novel proteins within stressed cells, and the key signal stimulating this appearance was identified as the presence of unfolded proteins within the cell. It is now known that this is a key mechanism enabling cells to survive a multitude of physical, chemical and biological stresses. Since the promulgation of the ‘molecular chaperone’ concept as a general cellular function to control the process of correct protein folding, a large number of molecular chaperones and protein folding catalysts have been identified, and it has been recognized that not all molecular chaperones are stress proteins and vice versa. The discovery of molecular chaperones as folding proteins went hand-in-hand with their recognition as potent immunogens in microbial infection. It was subsequently shown that administration of molecular chaperones such as Hsp60, Hsp70 or Hsp90 could inhibit experimental autoimmune diseases and cancer. More recently evidence has accumulated to show that certain molecular chaperones are also present on the surface of cells or in extracellular fluids. A new paradigm is emerging: at least some molecular chaperones are secreted proteins with pro- or anti-inflammatory actions, regulating the immune response in human diseases such as coronary heart disease, diabetes and rheumatoid arthritis. In addition to having direct effects on cells, molecular chaperones can bind peptides and present them to T cells to modulate immune responses. This may be significant in the treatment of cancer. This is the first book bringing leading researchers in this field together to review and discuss: our current knowledge of cell stress response and molecular chaperones the changing paradigms of protein trafficking and function cell stress proteins as immunomodulators and pro- and anti-inflammatory signalling molecules the role of these proteins in various chronic diseases and their potential as preventative or therapeutic agents. The Biology of Extracellular Molecular Chaperones is of particular interest to immunologists, cell and molecular biologists, microbiologists and virologists, as well as clinical researchers working in cardiology, diabetes, rheumatoid arthritis and other inflammatory diseases.

Protein homeostasis, or “Proteostasis”, lies at the heart of human health and disease. From the folding of single polypeptide chains into functional proteins, to the regulation of intracellular signaling pathways, to the secreted signals that coordinate cells in tissues and throughout the body, the proteostasis network operates to support cell health and physiological fitness. However, cancer cells also hijack the proteostasis network and many of these same processes to sustain the growth and spread of tumors. The chapters in this book are written by world experts in the many facets of the proteostasis network. They describe cutting-edge insights into the structure and function of the major chaperone and degradation systems in healthy cells and how these systems are co-opted in cancer cells and the cells of the tumor microenvironment. The chapters also cover therapeutic interventions such as the FDA-approved proteasome inhibitors Velcade and Krypolis as well as other therapies currently under clinical investigation to disarm the ability of the proteostasis network to support malignancy. This compendium is the first of its kind and aims to serve as a reference manual for active investigators and a primer for newcomers to the field. This book is dedicated to the memory of Susan Lindquist, a pioneer of the proteostasis field and a champion of the power of basic scientific inquiry to unlock the mechanisms of human disease. The chapter “Reflections and Outlook on Targeting HSP90, HSP70 and HSF1 in Cancer: A Personal Perspective” is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.

Currently one of the hottest topics in biochemistry, the concept of molecular chaperones has challenged the paradigm of protein self-assembly. Key figures in many disciplines review all aspects of molecular chaperones in this volume, which arises from a Royal Society discussion meeting. Overview chapters discuss the significance of chaperones in biochemistry, molecular genetics and cell biology. Each chapter is well referenced providing access to the literature.

Assisting Oxidative Protein Folding: How Do Protein Disulphide-Isomerases Couple Conformational and Chemical Processes in Protein Folding?, by A. Katrine Wallis and Robert B. Freedman Peptide Bond cis/trans Isomerases: A Biocatalysis Perspective of Conformational Dynamics in Proteins, by Cordelia Schiene-Fischer, Tobias Aumüller and Gunter Fischer Small Heat-Shock Proteins: Paramedics of the Cell, by Gillian R. Hilton, Hadi Lioe, Florian Stengel, Andrew J. Baldwin und Justin L. P. Benesch Allostery in the Hsp70 Chaperone Proteins, by Erik R. P. Zuiderweg, Eric B. Bertelsen, Aikaterini Rousaki, Matthias P. Mayer, Jason E. Gestwicki and Atta Ahmad Hsp90: Structure and Function, by Sophie E. Jackson Extracellular Chaperones, by Rebecca A. Dabbs, Amy R. Wyatt, Justin J. Yerbury, Heath Ecroyd and Mark R. Wilson