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This book describes the diverse roles that growth factors and cytokines play in skeletal muscle. The extracellular environment has profound effects on the biology of skeletal muscle. The soluble portion of this environment includes a rich milieu of growth factors and cytokines which have been shown to regulate virtually all facets of the response of skeletal muscle to external stimuli, whether it be exercise induced metabolic shifts, remodeling in response to trauma or loading of the ongoing pathology associated with neuromuscular disease. The chapters included in this work illustrate growth factors that directly affect skeletal muscle cells and those which influence non-muscle cells that contribute to the biology of skeletal muscle as a whole tissue. The current state of the art, with the advent of systems biology, allows for the delineation of signaling networks which are regulated by suites of growth factors. This is in stark contrast to early more traditional studies, which only examined the effects of isolated growth factors on the activity of skeletal muscle precursor cells in tissue culture. The work presented in this volume ranges from reviewing and analyzing the roles of individual growth factors in detail, to the complex interplay of multiple soluble factors in the control of muscle functional, and dysfunctional states. The material covered in this volume will particularly suit readers from a range of research fields spanning general muscle biology and physiology, and those working on diseases and conditions affecting skeletal muscle both directly and indirectly

Cytokines are an incredibly diverse group of secreted proteins with equally diverse functions. The actions of cytokines are mediated by the unique and sometimes overlapping receptors to which the soluble ligands bind. Classified within the interleukin-6 family of cytokines are leukemia inhibitory factor (LIF), oncostatin-M (OSM), cardiotrophin-1 (CT-1) and ciliary neurotrophic factor (CNTF). These cytokines all bind to the leukemia inhibitory factor receptor (LIFR) and gp130, and in some cases an additional receptor subunit, leading to activation of downstream kinases and transcriptional activators. LIFR is expressed on a broad range of cell types and can generate pleiotropic effects. In the context of skeletal muscle physiology, these cytokines have been shown to exert effects on motor neurons, inflammatory and muscle cells. From isolated cells through to whole organisms, manipulations of LIFR signaling cytokines have a wide range of outcomes influencing muscle cell growth, myogenic differentiation, response to exercise, metabolism, neural innervation and recruitment of inflammatory cells to sites of muscle injury. This article will discuss the shared and distinct processes that LIFR cytokines regulate in a variety of experimental models with the common theme of skeletal muscle physiology.