Rosselló Catalina Ana, Lindström Lisa, Glindre Johan, Eklund Greta, Alvarado-Kristensson Maria
Division of Molecular Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, 20502. Sweden.
Heliyon. 2016 Sep 24;2(9):e00166. doi: 10.1016/j.heliyon.2016.e00166. eCollection 2016 Sep.
The cytosolic role of γ-tubulin as a microtubule organizer has been studied thoroughly, but its nuclear function is poorly understood. Here, we show that γ-tubulin is located throughout the chromatin of demembranated sperm and, as the nucleus is formed, γ-tubulin recruits lamin B3 and nuclear membranes. Immunodepletion of γ-tubulin impairs assembly of both the lamina and the nuclear membrane. During nuclear formation in mammalian cell lines, γ-tubulin establishes a cellular protein boundary around chromatin that coordinates nuclear assembly of the daughter nuclei. Furthermore, expression of a γ-tubulin mutant that lacks the DNA-binding domain forms chromatin-empty nuclear like structures and demonstrate that a constant interplay between the chromatin-associated and the cytosolic pools of γ-tubulin is required and, when the balance between pools is impaired, aberrant nuclei are formed. We therefore propose that the nuclear protein meshwork formed by γ-tubulin around chromatin coordinates nuclear formation in eukaryotic cells.
γ-微管蛋白作为微管组织中心的胞质功能已得到充分研究，但其核功能却知之甚少。在此，我们表明γ-微管蛋白遍布去膜精子的染色质，并且在细胞核形成时，γ-微管蛋白招募核纤层蛋白B3和核膜。γ-微管蛋白的免疫去除会损害核纤层和核膜的组装。在哺乳动物细胞系的细胞核形成过程中，γ-微管蛋白在染色质周围建立了一个细胞蛋白边界，协调子细胞核的核组装。此外，缺乏DNA结合结构域的γ-微管蛋白突变体的表达形成了无染色质的类核结构，并证明γ-微管蛋白的染色质相关池和胞质池之间需要持续的相互作用，当池之间的平衡受到损害时，就会形成异常细胞核。因此，我们提出由γ-微管蛋白在染色质周围形成的核蛋白网络协调真核细胞中的核形成。
