Clathrin-coated vesicles form a unique net-like structure in liver sinusoidal endothelial cells by assembling along undisrupted microtubules.
Liver sinusoidal endothelial cells (LSECs) are highly active professional scavenger cells using clathrin-mediated endocytosis to clear the blood from macromolecular waste products. Using confocal microscopy, we observed a remarkable net-like distribution of clathrin heavy chain (CHC) in LSECs while all other cell types examined including various primary endothelial cells and cell lines showed the well-known punctuate staining pattern representing clathrin-coated vesicles (CCV). The net-like distribution of CHC in LSECs co-localized fully with microtubules, but not with actin. Upon 3D imaging, the net-like distribution of CHC resolved into numerous CCVs organized along the microtubules. The CCVs only partially co-localized with early endosome antigen 1 (EEA1) and adaptor protein 2 (AP-2). Endocytic vesicles containing ligand destined for degradation (FITC-AHGG) were organized along the clathrin/tubulin net-like structures, whereas transferrin-containing recycling vesicles co-localized to a much lower extent. Disruption of the microtubules by nocodazole treatment caused a collapse of the net-like organization of CCVs as well as a profound redistribution of EEA1, AP-2 and FITC-AHGG-containing vesicles, while transferrin internalization and recycling remained unaffected.
Falkowska-Hansen
Berit
B
Department of Dermatology, University Medical Center Mannheim, Ruprecht-Karls University Heidelberg, Theodor-Kutzer-Ufer 1-3, 68163 Mannheim, Germany. B.Falkowska-Hansen@DKFZ-Heidelberg.de
Falkowski
Martin
M
Metharom
Pat
P
Krunic
Damir
D
Goerdt
Sergij
S
D033962:Adaptor Protein Complex 2 / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002966:Clathrin / Q000737:chemistry / Q000378:metabolism*; D033922:Clathrin Heavy Chains / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism / Q000648:ultrastructure*; D004705:Endocytosis / Q000502:physiology; D042783:Endothelial Cells / Q000378:metabolism / Q000648:ultrastructure*; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000378:metabolism / Q000648:ultrastructure*; D046911:Macromolecular Substances / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure*; D010586:Phagocytes / Q000378:metabolism / Q000648:ultrastructure*; D010587:Phagocytosis / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014168:Transferrin / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
D033962:Adaptor Protein Complex 2; D002966:Clathrin; D046911:Macromolecular Substances; D008565:Membrane Proteins; D014168:Transferrin; D014404:Tubulin; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; D033922:Clathrin Heavy Chains; D016650:Fluorescein-5-isothiocyanate