Birbeck Granule-Like “Organized Smooth Endoplasmic Reticulum” Resulting from the Expression of a Cytoplasmic YFP-Tagged Langerin

摘要: Langerin is required for the biogenesis of Birbeck granules (BGs), characteristic organelles Langerhans cells. We previously used a Langerin-YFP fusion protein having C-terminal luminal YFP tag to dynamically decipher molecular and cellular processes which accompany traffic Langerin. In order elucidate interactions with its trafficking effectors their structural impact on BGs, we generated YFP-Langerin chimera an N-terminal, cytosolic tag. This latter induced formation YFP-positive large puncta. Live cell imaging coupled fluorescence recovery after photobleaching approach showed that this coalescence proteins in newly formed compartments was static. contrast, structures present pericentriolar region cells expressing chimera, displayed fluorescent characteristics compatible active membrane exchanges. Using correlative light-electron microscopy coalescent represented highly organized stacks membranes pentalaminar architecture typical BGs. Continuities between these rough endoplasmic reticulum allowed us identify as form “Organized Smooth Endoplasmic Reticulum” (OSER), distinct physiological properties. The involvement homotypic cytoplasmic molecules demonstrated using A206K variant YFP, restored most BG observed Mutation carbohydrate recognition domain also blocked OSER. Hence, “double-lock” mechanism governs behavior YFP-Langerin, where asymmetric homodimerization lectin domains participate retention subsequent BG-like These observations confirm appear wherever accumulates dictate physiology and, illustrate importance intracellular membranes.