Non-centrosomal microtubule arrays serve crucial functions in cells, yet the mechanisms of their generation are poorly understood. During budding of the epithelial tubes of the salivary glands in the Drosophila embryo, we previously demonstrated that the activity of pulsatile apical-medial actomyosin depends on a longitudinal non-centrosomal microtubule array. Here we uncover that the exit from the last embryonic division cycle of the epidermal cells of the salivary gland placode leads to the mother centrosome in the cells losing all microtubule-nucleation capacity. This restriction of nucleation activity to the daughter centrosome is key for proper morphogenesis. Furthermore, the microtubule-severing protein Katanin and the minus-end-binding protein Patronin accumulate in an apical-medial position only in placodal cells. Loss of either in the placode prevents formation of the longitudinal microtubule array and leads to loss of apical-medial actomyosin and apical constriction. We thus propose a mechanism whereby Katanin-severing at the single active centrosome releases microtubule minus-ends that are then anchored by apical-medial Patronin to promote formation of the longitudinal microtubule array crucial for apical constriction and tube formation.

中文翻译：

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释放和捕获机制在管芽过程中产生基本的非中心体微管阵列

非中心体微管阵列在细胞中起着至关重要的作用，但对其产生的机制了解甚少。在果蝇胚胎唾液腺上皮管的出芽过程中，我们以前证明了搏动性心尖-肌动球蛋白的活性取决于纵向的非中心微管阵列。在这里，我们发现唾液腺斑马的表皮细胞的最后一个胚胎分裂周期的退出导致细胞中的母体中心体失去了所有微管成核能力。子中心体对成核活性的这种限制是适当形态发生的关键。此外，微管切割蛋白Katanin和负端结合蛋白Patronin仅在睑板腺细胞中积累在根尖-中间位置。斑块中任一个的损失均阻止了纵向微管阵列的形成，并导致了根尖-内侧放线菌素的丢失和根尖的收缩。因此，我们提出了一种机制，其中在单个活性中心体处切断Katanin会释放微管负端，然后再由顶-中侧守护神锚定锚，以促进纵向微管阵列的形成，这对顶部收缩和管形成至关重要。