Cell Growth: Control of Cell Size

Edited by:
  • Michael N. Hall,
  • Martin Raff &
  • George Thomas
Cold Spring Harbor Laboratory Press • 2004 $135/£95

Multicellular creatures are much larger than the fertilized eggs from which they derive. This tremendous increase in the overall mass of an organism is achieved by the growth of individual cells. Growth occurs when the rate of synthesis of cellular macromolecules exceeds their rate of degradation. There has been a tendency to assume that growth occurs in a steady, unregulated — and therefore boring — manner, and the interesting issues in developmental biology address how changes in gene expression patterns, cell shape, cell adhesion and cell migration determine the form and composition of a developing organism. Michael Hall, Martin Raff and George Thomas, as editors of the recently published book Cell Growth: Control of Cell Size, have now set out to correct this misconception.

Despite the prevailing bias, it is clear that cell growth is indeed regulated — and in interesting ways. Cells come in all shapes and sizes, and individual cells may grow, or not grow, at specific stages in the life cycle of an organism. Specific cell types typically have a characteristic size in vivo, indicating that their rates of growth and division have been coordinated to arrive at this endpoint. Halting growth is equally important and of particular relevance in determining the final size of an organism. For instance, even though their gastrulating embryos are comparable in size, the cells in a developing elephant must grow and divide for much longer than those in a mouse. And finally, inappropriate cell growth also underlies tumour development.

Despite their importance, the mechanisms that regulate cell and tissue growth receive scant attention in most textbooks. Different aspects of growth are usually dealt with separately: chapters on metabolism and biosynthetic pathways are typically well insulated from those on cell-cycle regulation. Similarly, discussions on cell growth and developmental mechanisms are seldom connected. Also lacking is any one book with a cohesive description of the role of cell growth regulation during development and how growth regulation mechanisms impinge on pathways controlling the biosynthesis and degradation of cellular macromolecules. The editors of Cell Growth: Control of Cell Size have now attempted to fill this void.

The book is composed of twenty chapters that cover various aspects of growth regulation. Because each chapter is written by a different set of authors, they vary considerably in style, scope, approach and detail. Some are brief chapters that highlight important concepts, whereas others attempt to provide a comprehensive discussion of the relevant literature. Despite these differences, all the chapters are of generally high quality; perhaps not surprising if one considers that the contributors have done some of the most important work in the covered topics.

The book begins with an excellent, although brief, foreword on the principles of cell-size regulation and a first chapter — How Metazoans Reach Their Full Size: The Natural History of Bigness — that discusses key concepts connecting cell growth to organism size. Together, they provide a pleasing intellectual framework for the entire book, and each chapter would also be appropriate as teaching material in a graduate student class. The rest of the book consists of chapters covering more specialized topics. Three chapters focus on the relationship between growth and cell-cycle progression, and the interplay between them that determines cell size in different model systems. The next five chapters address different aspects of two key signalling pathways that regulate cell and tissue growth: the insulin/insulin-like growth factor pathway, which functions through phosphatidylinositol-3-OH kinase, and the nutrient-responsive signalling pathway, which functions through the target of rapamycin (TOR) or mammalian TOR (mTOR) protein kinase. Three chapters cover the 'nuts and bolts' of cell growth: protein translation, ribosome biogenesis, and the production of rRNA and tRNA, followed by a brief chapter on autophagy in yeast. Six chapters present discussions on growth regulation in more specialized contexts, such as at the synapse and in lymphocytes Finally, the book concludes with a brief chapter on growth regulation in plant cells.

The book is encyclopaedic in scope, and covers most aspects of growth regulation. I only wish that it also had a more detailed description of the key experiments in yeast cells that helped define the interrelationship between growth and cell-cycle progression and that led to the concept of a size checkpoint. I read the entire book (as I was asked to review it!) and learnt a lot, and I am sure that I will refer to it frequently. However, I suspect that many readers will pick and choose and read those chapters that are of particular interest to them, and will use other chapters as a reference source. I certainly believe that this book is a 'must-have' for laboratories that work on any area of growth regulation, and for libraries that are used by students of biology.

Cell Growth: Control of Cell Size is an authoritative and detailed book on growth regulation. We now need a second book on the same subject that is written at a more basic level, suitable for undergraduates to read from cover to cover — something at the level of The Making of a Fly by Peter Lawrence or The Cell Cycle by Andrew Murray and Tim Hunt. Perhaps one of the editors of Cell Growth: Control of Cell Size could be persuaded to embark on such a venture.