An expanding role for lipids in complex biological processes
Several areas of research into lipids and lipid signaling have experienced rapid growth in recent years, and the 2012 annual meeting sessions will highlight some of the most exciting new developments in lipid biology. Four general topics will be covered in four sessions, including the formation and dissolution of lipid droplets, metabolite partitioning in mammalian tissues and model organisms, the contributions of lipids to inflammation and infectious disease, and lipid signals that control protein function.
Recent research reveals that lipid droplets are an important storage compartment for signaling lipids, substrates for energy metabolism and intermediates for the synthesis of membrane lipids. Speakers in the first session, “Lipid Droplets: A Dynamic Subcellular Compartment,” will address current thoughts about lipid droplet formation and metabolism.
David L. Silver (Albert Einstein College of Medicine) will present evidence that members of the FIT family of proteins are essential for the packaging of triglyceride into nascent lipid droplets. FIT proteins are integral membrane proteins in the endoplasmic reticulum that facilitate the partitioning of triglycerides into lipid droplets and, as such, are required for lipid droplet expansion.
Tobias Walther (Yale University) will continue the theme by describing investigations into the role of phospholipids in lipid droplet formation and dynamics.
Finally, Dawn L. Brasaemle (Rutgers University) will describe how members of the perilipin family of lipid droplet-associated proteins fine-tune triglyceride storage in lipid droplets through control of lipase access to lipid substrates.
A developing area of inquiry is how lipids are channeled from biosynthetic or catabolic enzymes to specific fates in different subcellular compartments. Moreover, various proteins serve multiple functions, providing enzymatic activity against lipid substrates while influencing either lipid partitioning or transcription.
In “Metabolic Branchpoints and Lipid Channeling,” Deborah M. Muoio (Duke University) will discuss the relationship between incomplete fat oxidation and the pathophysiology of insulin resistance in muscle as an example of how altered flux of metabolites can perturb energy balance.
Kaveh Ashrafi (University of California, San Francisco) will describe recent whole-organism studies in C. elegans to identify novel pathways and compounds that influence fat storage.
The third speaker, Peter J. Espenshade (Johns Hopkins University School of Medicine) will examine the regulation of lipid metabolism by cellular sterol levels and hypoxia through modulation of the sterol regulatory element-binding protein pathway in fission yeast.
Lipids and inflammation
The third session, “Lipid Signaling, Infection, and Atherosclerosis,” will explore the role of cellular lipid metabolism in modulating the host-pathogen interface. Christopher K. Glass (University of California, San Diego) will discuss oxysterols and cholesterol synthesis intermediates as LXR agonists for the regulation of gene expression related to Toll-like receptor signaling in macrophages.
Timothy F. Osborne (Sanford-Burnham Medical Research Institute) will expand on the link between the regulation of lipogenesis by SREBPs and innate immune pathways crucial for macrophage function.
Finally, Melanie Ott (The Gladstone Institute of Virology and Immunology) will describe the role that lipid metabolism plays in the propagation of the hepatitis C virus in the liver.
The final session, “Lipid Regulation of Protein Function,” will focus on lipid modulation of protein function through direct interactions as either ligands for transcription factors or modulators of intracellular signaling pathways.
Fraydoon Rastinejad (Sanford-Burnham Medical Research Institute) will describe his recent structural studies of full-length nuclear receptors bound to DNA and how unique protein-protein, protein-DNA and protein-lipid interactions have been revealed and have revolutionized our understanding of how ligands alter complex assembly to influence gene expression.
Benjamin F. Cravatt (The Scripps Research Institute) will present recent data on the enzymes required for metabolism of bioactive lipid amides known as endocannabinoids, which bind to G-protein-coupled receptors to initiate signals with diverse effects on pain perception, behavior, appetite and metabolism.
The third speaker, Jerrold M. Olefsky (University of California, San Diego) will discuss how macrophage-mediated inflammation influences lipid signaling that contributes to obesity-related insulin resistance.
Dawn L. Brasaemle (Brasaemle@aesop.rutgers.edu) is an associate professor of nutritional sciences at Rutgers University, and Timothy F. Osborne (email@example.com) is professor and director of the metabolic signaling and disease program at Sanford-Burnham Medical Research Institute, Lake Nona.