RT Journal Article
SR Electronic
T1 A Membrane Pool Retrieved via Endocytosis Overshoot at Nerve Terminals: A Study of Its Retrieval Mechanism and Role
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3398
OP 3404
DO 10.1523/JNEUROSCI.5943-11.2012
VO 32
IS 10
A1 Lei Xue
A1 Benjamin D. McNeil
A1 Xin-Sheng Wu
A1 Fujun Luo
A1 Liming He
A1 Ling-Gang Wu
YR 2012
UL http://www.jneurosci.org/content/32/10/3398.abstract
AB Endocytosis overshoot, which retrieves more membrane than vesicles just being exocytosed, occurs at nerve terminals and non-neuronal secretory cells. The mechanism that retrieves the overshoot membrane pool and the role of this pool remain largely unknown. We addressed this issue at the rat calyx of Held nerve terminal with capacitance measurements. We found that every calyx contained an overshoot pool ∼1.8 times the readily releasable pool. Retrieval of this pool required large calcium influx, and was inhibited by blockers of calcium/calmodulin-activated calcineurin and dynamin, suggesting the involvement of calcineurin and dynamin in endocytosis overshoot. Depletion of the overshoot pool slowed down compensatory endocytosis, whereas recovery of the overshoot pool via exocytosis that deposited stranded vesicles to the plasma membrane led to recovery of compensatory endocytosis, suggesting that the overshoot pool enhances endocytosis efficiency. These results suggest that the overshoot pool exists at every nerve terminal, is of limited size arising from vesicles stranded at the plasma membrane, is retrieved via calcium/calmodulin/calcineurin and dynamin signaling pathway, and can enhance endocytosis efficiency. Potential mechanisms for how the endocytosis overshoot pool enhances endocytosis efficiency are discussed.