Kanagaraj Palsamy, Gautier-Stein Amandine, Riedel Dietmar, Schomburg Christoph, Cerdà Joan, Vollack Nadine, Dosch Roland
Institut fuer Entwicklungsbiochemie, Georg-August Universitaet Goettingen, Goettingen, Germany.
Departement de Zoologie et Biologie Animale, Universite de Geneve, Geneva, Switzerland.
PLoS Genet. 2014 Jun 26;10(6):e1004449. doi: 10.1371/journal.pgen.1004449. eCollection 2014 Jun.
During oogenesis, the egg prepares for fertilization and early embryogenesis. As a consequence, vesicle transport is very active during vitellogenesis, and oocytes are an outstanding system to study regulators of membrane trafficking. Here, we combine zebrafish genetics and the oocyte model to identify the molecular lesion underlying the zebrafish souffle (suf) mutation. We demonstrate that suf encodes the homolog of the Hereditary Spastic Paraplegia (HSP) gene SPASTIZIN (SPG15). We show that in zebrafish oocytes suf mutants accumulate Rab11b-positive vesicles, but trafficking of recycling endosomes is not affected. Instead, we detect Suf/Spastizin on cortical granules, which undergo regulated secretion. We demonstrate genetically that Suf is essential for granule maturation into secretion competent dense-core vesicles describing a novel role for Suf in vesicle maturation. Interestingly, in suf mutants immature, secretory precursors accumulate, because they fail to pinch-off Clathrin-coated buds. Moreover, pharmacological inhibition of the abscission regulator Dynamin leads to an accumulation of immature secretory granules and mimics the suf phenotype. Our results identify a novel regulator of secretory vesicle formation in the zebrafish oocyte. In addition, we describe an uncharacterized cellular mechanism for Suf/Spastizin activity during secretion, which raises the possibility of novel therapeutic avenues for HSP research.
在卵子发生过程中，卵子为受精和早期胚胎发育做准备。因此，在卵黄发生期间囊泡运输非常活跃，卵母细胞是研究膜运输调节因子的一个出色系统。在这里，我们结合斑马鱼遗传学和卵母细胞模型来确定斑马鱼 souffle（suf）突变背后的分子损伤。我们证明suf编码遗传性痉挛性截瘫（HSP）基因SPASTIZIN（SPG15）的同源物。我们表明，在斑马鱼卵母细胞中，suf突变体积累Rab11b阳性囊泡，但回收内体的运输不受影响。相反，我们在经历调节性分泌的皮质颗粒上检测到Suf/Spastizin。我们通过遗传学证明Suf对于颗粒成熟为具有分泌能力的致密核心囊泡至关重要，这描述了Suf在囊泡成熟中的新作用。有趣的是，在suf突变体中，未成熟的分泌前体积累，因为它们无法从网格蛋白包被的芽上脱离。此外，对分裂调节因子发动蛋白的药理学抑制导致未成熟分泌颗粒的积累，并模拟了suf表型。我们的结果确定了斑马鱼卵母细胞中分泌囊泡形成的一种新调节因子。此外，我们描述了分泌过程中Suf/Spastizin活性的一种未表征的细胞机制，这为HSP研究开辟新治疗途径带来了可能性。
