title: Vesicle Size Regulates Nanotube Formation in the Cell.
abstract: Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro studies also lack physiological relevance. Here, we use lysosomes and autolysosomes, whose sizes range between 100 nm and 1 μm, as model systems to study the size effects on nanotube formation both in vivo and in vitro. Single molecule observations indicate that driven by kinesin motors, small vesicles (100-200 nm) are mainly transported along the tracks while a remarkable portion of large vesicles (500-1000 nm) form nanotubes. This size effect is further confirmed by in vitro reconstitution assays on liposomes and purified lysosomes and autolysosomes. We also apply Atomic Force Microscopy (AFM) to measure the initiation force for nanotube formation. These results suggest that the size-dependence may be one of the mechanisms for cells to regulate cellular processes involving membrane-deformation, such as the timing of tubulation-mediated vesicle recycling.
authors.affiliation: State Key Laboratory of Membrane Biology, Biodynamic Optical Imaging Center, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Qian Peter
authors.initials: QP
authors.lastname: Su
authors.affiliation: State Key Laboratory of Membrane Biology, Tsinghua-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Wanqing
authors.initials: W
authors.lastname: Du
authors.affiliation: Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Membrane Biology, Biodynamic Optical Imaging Center, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Boxin
authors.initials: B
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Membrane Biology, Tsinghua-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Membrane Biology, Tsinghua-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Yueyao
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: He
authors.initials: H
authors.lastname: Ren
authors.affiliation: School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Chuanmao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Lou
authors.affiliation: State Key Laboratory of Membrane Biology, Tsinghua-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Membrane Biology, Biodynamic Optical Imaging Center, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000818:Animals; D000071182:Autophagosomes / Q000378:metabolism* / Q000648:ultrastructure; D001692:Biological Transport; D015153:Blotting, Western; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D016547:Kinesins / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism* / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D043942:Nanotubes / Q000032:analysis* / Q000648:ultrastructure; D051381:Rats; D061987:Sf9 Cells; D018411:Spodoptera; D053835:Unilamellar Liposomes / Q000378:metabolism*
chemical_list: C521566:KIF5B protein, rat; D053835:Unilamellar Liposomes; D016547:Kinesins