Endocrine Abstracts

Information transfer through cellular membranes relies upon recognition of the physical and chemical information surrounding the cell by specific proteins, called receptors located in the plasma membrane (PM). These receptors are coupled to various signal relaying systems in the inter leaflet of the PM to initiate the cascade of cellular events that is characteristic of the cell and the receptor. Several receptor types alter the activity of enzymes that liberate signalling molecules originating from PM lipids and therefore, also affect the membrane lipid composition. A particularly important lipid class that plays pivotal roles in signal transduction is the phosphoinositides that not only serve as precursors of messenger molecules but also participate in recruiting and organizing protein signalling complexes on the surface of various membranes, including the PM. Moreover, increasing evidence suggest that some of the phosphoinositide changes are critical to regulate non-vesicular lipid transfer between membrane contact sites formed between various organelles. Given the small amounts of these regulatory lipids and their rapid and spatially confined changes, new approaches are required for their detection and rapid manipulation. In this presentation, we will review our most recent advances in understanding phosphoinositide dynamics and the way they contribute to the complex organization of PM receptor function and subsequent downstream signalling events. We will also discuss the principles of how these small regulatory lipids can control the overall lipid homeostasis of the cell and show examples of signal organization in specialized contact zones formed between the ER and the PM.