Theoretical Biology Laboratory, RIKEN, Wako 351-0198, Japan;
Interdisciplinary Theoretical Science Research Group, RIKEN, Wako 351-0198, Japan.
Proc Natl Acad Sci U S A. 2017 May 16;114(20):5177-5182. doi: 10.1073/pnas.1619264114. Epub 2017 May 1.
The Golgi apparatus is a membrane-bounded organelle with the characteristic shape of a series of stacked flat cisternae. During mitosis in mammalian cells, the Golgi apparatus is once fragmented into small vesicles and then reassembled to form the characteristic shape again in each daughter cell. The mechanism and details of the reassembly process remain elusive. Here, by the physical simulation of a coarse-grained membrane model, we reconstructed the three-dimensional morphological dynamics of the Golgi reassembly process. Considering the stability of the interphase Golgi shape, we introduce two hypothetical mechanisms-the Golgi rim stabilizer protein and curvature-dependent restriction on membrane fusion-into the general biomembrane model. We show that the characteristic Golgi shape is spontaneously organized from the assembly of vesicles by proper tuning of the two additional mechanisms, i.e., the Golgi reassembly process is modeled as self-organization. We also demonstrate that the fine Golgi shape forms via a balance of three reaction speeds: vesicle aggregation, membrane fusion, and shape relaxation. Moreover, the membrane fusion activity decreases thickness and the number of stacked cisternae of the emerging shapes.
高尔基器是一种具有一系列堆叠的扁平潴泡特征形状的膜结合细胞器。在哺乳动物细胞的有丝分裂过程中，高尔基器首先被分割成小泡，然后在每个子细胞中重新组装形成特征形状。但是，其重新组装的机制和细节仍不清楚。在这里，我们通过粗粒化膜模型的物理模拟，重建了高尔基体重新组装过程的三维形态动力学。考虑到间期高尔基器形状的稳定性，我们将两个假设机制（高尔基器边缘稳定蛋白和对膜融合的曲率依赖性限制）引入到一般的生物膜模型中。我们表明，通过适当调整这两个附加机制，特征性的高尔基器形状是由小泡的组装自发组织形成的，即高尔基体的重新组装过程被建模为自组织。我们还证明，精细的高尔基器形状是通过小泡聚集、膜融合和形状松弛这三种反应速度的平衡来形成的。此外，膜融合活性降低了新形成的形状的厚度和堆叠潴泡的数量。
