1. Preformed Ω-profile closure and kiss-and-run mediate endocytosis and diverse endocytic modes in neuroendocrine chromaffin cells.
- Author
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Shin W, Wei L, Arpino G, Ge L, Guo X, Chan CY, Hamid E, Shupliakov O, Bleck CKE, and Wu LG
- Subjects
- Animals, Calcium Signaling, Cattle, Cell Fusion, Cell Membrane physiology, Cell Membrane ultrastructure, Computer Systems, Dynamins physiology, Exocytosis physiology, Membrane Fusion, Primary Cell Culture, Synaptic Vesicles metabolism, Chromaffin Cells physiology, Chromaffin Cells ultrastructure, Endocytosis physiology, Neuroendocrine Cells physiology, Neuroendocrine Cells ultrastructure
- Abstract
Transformation of flat membrane into round vesicles is generally thought to underlie endocytosis and produce speed-, amount-, and vesicle-size-specific endocytic modes. Visualizing depolarization-induced exocytic and endocytic membrane transformation in live neuroendocrine chromaffin cells, we found that flat membrane is transformed into Λ-shaped, Ω-shaped, and O-shaped vesicles via invagination, Λ-base constriction, and Ω-pore constriction, respectively. Surprisingly, endocytic vesicle formation is predominantly from not flat-membrane-to-round-vesicle transformation but calcium-triggered and dynamin-mediated closure of (1) Ω profiles formed before depolarization and (2) fusion pores (called kiss-and-run). Varying calcium influxes control the speed, number, and vesicle size of these pore closures, resulting in speed-specific slow (more than ∼6 s), fast (less than ∼6 s), or ultrafast (<0.6 s) endocytosis, amount-specific compensatory endocytosis (endocytosis = exocytosis) or overshoot endocytosis (endocytosis > exocytosis), and size-specific bulk endocytosis. These findings reveal major membrane transformation mechanisms underlying endocytosis, diverse endocytic modes, and exocytosis-endocytosis coupling, calling for correction of the half-a-century concept that the flat-to-round transformation predominantly mediates endocytosis after physiological stimulation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021. Published by Elsevier Inc.)
- Published
- 2021
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