Membrane Protein Cytoskeleton Interactions

The plasma membrane acts as both a boundary and a site of exchange between the outside and the inside of a cell. The cytoskeleton plays essential roles in delineating membrane protein distributions, in defining structural and functional domains in the plasma membrane, and in regulating membrane protein, and ultimately, cell function. This volume reviews the regulation of membrane protein distribution, organization, and function at the plasma membrane by the cytoskeleton. Discussions also include the roles of cytoskeleton in the structural and functional organization of membranes and membrane proteins with emphasis on key problems, the current status of understanding, experimental approaches, and future directions.

In 1898 Camillo Golgi reported his newly observed intracellular structure, the apparato reticolare interno, now universally known as the Golgi Apparatus. The method he used was an ingenious histological technique (La reazione nera) which brought him fame for the discovery of neuronal networks and culminated in the award of the Nobel Prize for Physiology and Medicine in 1906. This technique, however, was not easily reproducible and led to a long-lasting controversy about the reality of the Golgi apparatus. Its identification as a ubiquitous organelle by electron microscopy turned out to be the breakthrough and incited an enormous wave of interest in this organelle at the end of the sixties. In recent years immunochemical techniques and molecular cloning approaches opened up new avenues and led to an ongoing resurgence of interest. The role of the Golgi apparatus in modifying, broadening and refining the structural information conferred by transcription/translation is now generally accepted but still incompletely understood. During the coming years, this topic certainly will remain center stage in the field of cell biology. The centennial of the discovery of this fascinating organelle prompted us to edit a new comprehensive book on the Golgi apparatus whose complexity necessitated the contributions of leading specialists in this field. This book is aimed at a broad readership of glycobiologists as well as cell and molecular biologists and may also be interesting for advanced students of biology and life sciences.

The term cytoskeleton has become firmly established in today's scientific vocabulary. Indeed, it is difficult to believe that only ten years ago, it was virtually non-existent. Since then, the modern field of research on the structural organization of the cytoplasm has turned into one of the most productive and rapidly expanding research areas in Cell Biology today. Considerable progress has been made towards the identification of the various structural components of the cytoskeleton and their interactions with one another and with membranes. The first attempts to understand, in molecular terms, complex cellular processes such as shape changes, locomotion, division, and organelle movements have been made. And it is now apparent that the cytoskeleton has impact on other biological processes such as the control of gene expression, protein synthesis, cell cycle regulation, and development. This monograph outlines the basic properties of the major components of the polymeric filament networks and their interactions and associations. Wherever possible, emphasis is placed on more recent references. Any attempt to cover a research field this complex in an introductory mono graph is, by necessity, fragmentary, and oversights or omissions are inevitable. I wish to apologize in advance to all those colleagues who feel that their work is not adequately represented.

Various cellular processes underlying plant development and response to environmental cues rely on a dynamic interplay between membranes and the cytoskeleton, e.g. vesicle and organelle trafficking, endocytosis, exocytosis, and signal transduction. In recent years, significant progress in the understanding of such interplay has been achieved and several critical links between membranes and the cytoskeleton have been characterized. As an example, recent work has clarified how auxin promotes the reorganization of cortical actin filaments by the activation of Rho GTPase pathways, and how such reorganization in turn locally modifies endocytosis and/or exocytosis and directs asymmetric distribution of PIN family of auxin transporters. Another recent achievement is the characterization of the Rho- and microtubule-driven mechanism by which the cell wall architecture is established. In particular, the elegant work by Oda and Fukuda (Science 337 p.1333, 2012) provides evidence that secondary wall patterning in xylem vessel primarily relies on two processes: a local activation of the plant Rho GTPase ROP11 and a mutual, MIDD1-mediated, inhibitory interaction between active ROP domains and cortical microtubules. Additional examples include recent genetic evidence that microtubule and actin filament interacting/regulatory proteins, such as MAP65-1 and capping protein, function as transducers of membrane lipid signaling into changes in cytoskeleton dynamics and organization. This Research Topic aims at collecting a comprehensive set of articles dealing with cellular processes involving membrane-cytoskeleton interactions. Its scope extends beyond the specific fields defined by the above examples and includes intracellular trafficking, host-pathogen interactions, response to biotic and abiotic stresses and hormonal regulation of growth. We hope that this Research Topic will also highlight critical questions that need to be addressed in the future. We welcomed Original Research Articles, Technical/Methodological Advances (e.g. analysis of cytoskeleton dynamics close to membranes), Reviews and Mini Reviews that can expand our understanding of how and why membranes and the cytoskeleton interact.

This text attempts to introduce the molecular biology of cell membranes to students and professionals of diverse backgrounds. Although several membrane biology books are available, they do not integrate recent knowledge gained using modern molecular tools with more traditional membrane topics. Molecular techniques, such as cDNA cloning and x-ray diffraction, have provided fresh insights into cell membrane structure and function. The great excitement today, which I attempt to convey in this book, is that molecular details are beginning to merge with physiological responses. In other words, we are beginning to understand precisely how membranes work. This textbook is appropriate for upper-level undergraduate or beginning graduate students. Readers should have previous or concurrent coursework in biochemistry; prior studies in elementary physiology would be helpful. I have found that the presentation of topics in this book is appropriate for students of biology, biochemistry, biophysics and physiology, chemistry, and medicine. This book will be useful in courses focusing on membranes and as a supplementary text in biochemistry courses. Professionals will also find this to be a useful resource book for their personal libraries.

The first volume of the Handbook deals with the amazing world of biomembranes and lipid bilayers. Part A describes all aspects related to the morphology of these membranes, beginning with the complex architecture of biomembranes, continues with a description of the bizarre morphology of lipid bilayers and concludes with technological applications of these membranes. The first two chapters deal with biomembranes, providing an introduction to the membranes of eucaryotes and a description of the evolution of membranes. The following chapters are concerned with different aspects of lipids including the physical properties of model membranes composed of lipid-protein mixtures, lateralphase separation of lipids and proteins and measurement of lipid-protein bilayer diffusion. Other chapters deal with the flexibility of fluid bilayers, the closure of bilayers into vesicles which attain a large variety of different shapes, and applications of lipid vesicles and liposomes. Part B covers membrane adhesion, membrane fusion and the interaction of biomembranes withpolymer networks such as the cytoskeleton. The first two chapters of this part discuss the generic interactions of membranes from the conceptual point of view. The following two chapters summarize the experimental work on two different bilayer systems. The next chapter deals with the process ofcontact formation, focal bounding and macroscopic contacts between cells. The cytoskeleton within eucaryotic cells consists of a network of relatively stiff filaments of which three different types of filaments have been identified. As explained in the next chapter much has been recently learned aboutthe interaction of these filaments with the cell membrane. The final two chapters deal with membrane fusion.