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Talk by Anne Spang

Title: "Principles of cellular compartmentalization"
Occasion: SFB Special Seminar
Start: 22.05.2024 - 16:15
Location: CellNanOs, 38/201

About the speaker: Prof. Dr. Anne Spang conducts research at the Biozentrum, University of Basel, Switzerland.

Abstract of the talk: Eukaryotic cells contain membrane-bounded organelles to separate distinct cellular functions. Nevertheless, the organelles need to communicate with each other and the extracellular space. Specialized domains on organelles and the plasma membrane support communication through at least three different ways:
1) transport vesicles that are formed at a donor compartment -exit site- and fuse with and are consumed at a specific target compartment -arrival site-
2) transport containers/organelles that briefly fuse with each other, yet maintain their overall identity, a mechanism referred to as 'kiss-and-run'
3) membrane contact sites at which two compartments come into very close contact that allows exchange of lipids and ions between organelles or organelles and the plasma membrane.
Key regulators of these specialized compartments are small GTPases of the Arf and Rab families. In their activated, GTP-bound state, they recruit effector molecules, which locally change the membrane and protein environment and thus give raise to specialized compartments. These small GTPases are regulated themselves through the action of GEFs and GAPs allowing for the tighlty temporal and spatial control of GTPase activity and hence membrane compartmentalization. Compartmentalization is not restricted to membranes but takes also place in the nucleus and the cytoplasm, where membrane-less condensates are formed to fulfill dedicated functions. For example, under stress, processing bodies and stress
granules form in the cytoplasm and degrade or store RNA. When stress subsides, they can be turned over, and some RNA can even be returned to translation. I will discuss our current understanding of intracellular compartmentalization, rules that govern these processes and where we are headed, with a special emphasis on the endosomal system.