PT  - JOURNAL ARTICLE
AU  - Lei Xue
AU  - Benjamin D. McNeil
AU  - Xin-Sheng Wu
AU  - Fujun Luo
AU  - Liming He
AU  - Ling-Gang Wu
TI  - A Membrane Pool Retrieved via Endocytosis Overshoot at Nerve Terminals: A Study of Its Retrieval Mechanism and Role
AID  - 10.1523/JNEUROSCI.5943-11.2012
DP  - 2012 Mar 07
TA  - The Journal of Neuroscience
PG  - 3398--3404
VI  - 32
IP  - 10
4099  - http://www.jneurosci.org/content/32/10/3398.short
4100  - http://www.jneurosci.org/content/32/10/3398.full
SO  - J. Neurosci.2012 Mar 07; 32
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.