Syncytial cells contain multiple nuclei and have local distribution and function of cellular components despite being synthesized in a common cytoplasm. The syncytial Drosophila blastoderm embryo shows reduced spread of organelle and plasma membrane-associated proteins between adjacent nucleo-cytoplasmic domains. Anchoring to the cytoarchitecture within a nucleo-cytoplasmic domain is likely to decrease the spread of molecules; however, its role in restricting this spread has not been assessed. In order to analyze the cellular mechanisms that regulate the rate of spread of plasma membrane-associated molecules in the syncytial Drosophila embryos, we express a pleckstrin homology (PH) domain in a localized manner at the anterior of the embryo by tagging it with the bicoid mRNA localization signal. Anteriorly expressed PH domain forms an exponential gradient in the anteroposterior axis with a longer length scale compared with Bicoid. Using a combination of experiments and theoretical modeling, we find that the characteristic distribution and length scale emerge due to plasma membrane sequestration and restriction within an energid. Loss of plasma membrane remodeling to form pseudocleavage furrows shows an enhanced spread of PH domain but not Bicoid. Modeling analysis suggests that the enhanced spread of the PH domain occurs due to the increased spread of the cytoplasmic population of the PH domain in pseudocleavage furrow mutants. Our analysis of cytoarchitecture interaction in regulating plasma membrane protein distribution and constraining its spread has implications on the mechanisms of spread of various molecules, such as morphogens in syncytial cells.

合体细胞含有多个细胞核，尽管是在共同的细胞质中合成的，但具有细胞成分的局部分布和功能。合胞体果蝇胚盘胚胎显示细胞器和质膜相关蛋白在相邻核质域之间的扩散减少。锚定在核质域内的细胞结构可能会减少分子的扩散；然而，其在限制这种传播方面的作用尚未得到评估。为了分析调节合胞体果蝇胚胎中质膜相关分子扩散速率的细胞机制，我们通过用bicoid标记，以局部方式在胚胎前部表达 pleckstrin 同源 (PH) 结构域。mRNA定位信号。与 Bicoid 相比，前面表达的 PH 结构域在前后轴上形成指数梯度，具有更长的长度尺度。通过实验和理论建模的结合，我们发现特征分布和长度尺度是由于质膜隔离和能量内的限制而出现的。质膜重塑的丧失形成假裂沟表明 PH 结构域的扩散增强，但 Bicoid 则没有。模型分析表明，PH 结构域的扩散增强是由于假裂沟突变体中 PH 结构域细胞质群体的扩散增加所致。