斑马鱼Poc1a基因在中性粒细胞发育中的作用及机制研究

Differentiaion and maturation of neutrophil is a key process for vertebrate embrynonic hematopoiesis and non-specific immune system establishment.Despite of several transcritpion factors and digestion proteins are found to be involved in neutrophil differentiation, the mechanism of neutrophil maturation is largely unknown.Based on the study of a neutrophil lineage deficient zebrafish mutant nld1, we showed that nld1 mutants had a no altered neutrophil number, but show more roundness cell shape, reduced granule number and impaired granule motility.By positional cloning, we mapped the causative gene Poc1a.It is indicated that Poc1a acts as a novel factor essential for neutrophil maturation in controlling granulocyte differentiation.In this proposal, we are going to define the cellular and molecular basis for devective granulopoiesis in nld1 mutant lucidate the molecular regulation and genetic interaction of known factors and Poc1a in neutrophil maturation regulatory pathway. Meanwhile, we are going to screen novel Poc1a interaction proteins to reveal new cellular and molecular mechanism in neutrophil maturation. Our study establishes a regulatory hierarchy during neutrophil maturation in which lineage is unique controlled by Poc1a.

中性粒细胞成熟分化是脊椎动物造血发育以及非特异性免疫系统建立的重要环节,虽有数个转录因子及消化酶参与调控了中性粒细胞的分化成熟，但胚胎期中性粒细胞的发育成熟的调控机制目前仍不明确。我们前期筛选得到了粒系造血缺陷的nld1(Neutrophil Lineage Deficient 1)斑马鱼突变体，并克隆到了可能的致变基因中心粒蛋白1a（Poc1a），我们的前期结果表明Poc1a调控了中性粒细胞的分化成熟过程：表现为细胞数目不变，但轮廓变圆、颗粒数目减少及颗粒运动性减弱，颗粒中的髓过氧化物酶活性减弱，并且细胞的随机变形运动增强。迄今未见有关Poc1a调控中性粒细胞发育的报道，因此我们将通过分析nld1突变体中性粒细胞的缺陷表型，研究Poc1a在中性粒细胞发育途径中与已知因子的分子间互作及遗传学调控关系，并通过筛选与Poc1a相互作用的蛋白来揭示调控中性粒细胞发育成熟的新的细胞学及分子机理。

中性粒细胞具有趋化作用、吞噬作用和杀菌作用，在免疫防御中发挥着重要的作用。然而，中性粒细胞发育成熟的调控网络大部分仍然未知。. 本项目中，我们正向遗传学筛选，获得中性粒细胞缺陷的斑马鱼突变体smu350，通过图位克隆，发现编码血红素合成酶Alas1基因为该突变体的致变基因。因此，我们利用中性粒细胞缺陷的斑马鱼突变体，研究Alas1在中性粒细胞发育中的作用。Alas1缺陷斑马鱼虽然展示出正常的中性粒细胞发生，但由于血红素不足，随后的中性粒细胞成熟受到阻碍，表现为脂质储存和颗粒形成障碍，血红素相关颗粒蛋白酶活性缺失，从而导致对细菌（大肠杆菌）的杀菌作用减弱，炎症应答反应异常增加。. 我们的结果揭示了Alas1通过合成血红素来调节中性粒细胞的成熟和生理学功能。该研究丰富了中性粒细胞发育成熟的调控网络，同时为血红素相关疾病的药物筛选和治疗策略提供了思路。