In neurosecretory cells, myosin VI associated with secretory granules (SGs) mediates their activity-dependent recruitment to the cortical actin network and is necessary to sustain exocytosis. The mechanism by which myosin VI interacts with SGs is unknown. Using a myosin VI pull-down assay and mass spectrometry we identified Mena, a member of the ENA/VASP family, as a myosin VI binding partner in PC12 cells, and confirmed that Mena colocalized with myosin VI on SGs. Using a knock-sideways approach to inactivate the ENA/VASP family members by mitochondrial relocation, we revealed a concomitant redistribution of myosin VI. This was ensued by a reduction in the association of myosin VI with SGs, a decreased SG mobility and density in proximity to the plasma membrane as well as decreased evoked exocytosis. These data demonstrate that ENA/VASP proteins regulate SG exocytosis through modulating the activity of myosin VI.

在神经分泌细胞中，与分泌颗粒（SGs​​）相关的肌球蛋白VI介导其依赖于活性的募集到皮质肌动蛋白网络，并且对于维持胞吐作用是必需的。肌球蛋白VI与SG相互作用的机制尚不清楚。使用肌球蛋白VI下拉测定法和质谱法，我们鉴定了ENA / VASP家族成员Mena作为PC12细胞中的肌球蛋白VI结合伴侣，并确认Mena与肌球蛋白VI在SGs上共定位。使用侧向敲除方法通过线粒体重定位灭活ENA / VASP家庭成员，我们揭示了肌球蛋白VI的伴随重新分布。这是由于肌球蛋白VI与SG的缔合减少，SG迁移率和质膜附近密度降低以及诱发的胞吐作用降低所致。