Cell:3D超解析度「電影」揭示細胞如何完成胞吞作用

近日，來自歐洲分子生物學實驗室的研究者通過將兩種不同類型的顯微技術結合起來開發出了「3D電影技術」來觀察細胞如何內吞營養物以及其它分子。相關研究刊登在了近日的國際雜誌Cell上。

細胞這種「吞咽作用」稱為細胞吞噬現象，是細胞完成的至關重要的任務。這個過程可以被許多病毒「劫持」，從而使得病毒達到侵染宿主細胞的目的。當細胞準備吞咽一些分子的時候，細胞膜表面會產生凹陷，逐漸地向內擴張，擠壓斷裂形成小包或者膜泡，從而將分子轉移入細胞內部。

為了研究細胞如何牽引細胞膜並且形成小囊泡的，研究者基於光學顯微鏡和高解析度顯微鏡技術開發了一種方法，這種新方法可以使研究者結合兩組數據來分析細胞是如何完成這個過程的。研究者發現第一個蛋白質達到細胞膜內部並不能夠使得細胞膜回折，直到細胞支架蛋白-肌動蛋白網絡形成以後才會開始彎折。

後期研究者將為這個過程中的蛋白質進行標記，通過打亂這些蛋白質研究者希望延伸一下當前的工作。（生物谷Bioon.com）

編譯自：3D movie at 'ultraresolution' shows how cell’s machinery bends membrane inwards

Plasma Membrane Reshaping during Endocytosis Is Revealed by Time-Resolved Electron Tomography

Wanda Kukulski, Martin Schorb, Marko Kaksonen, John A.G. Briggs

Endocytosis, like many dynamic cellular processes, requires precise temporal and spatial orchestration of complex protein machinery to mediate membrane budding. To understand how this machinery works, we directly correlated fluorescence microscopy of key protein pairs with electron tomography. We systematically located 211 endocytic intermediates, assigned each to a specific time window in endocytosis, and reconstructed their ultrastructure in 3D. The resulting virtual ultrastructural movie defines the protein-mediated membrane shape changes during endocytosis in budding yeast. It reveals that clathrin is recruited to flat membranes and does not initiate curvature. Instead, membrane invagination begins upon actin network assembly followed by amphiphysin binding to parallel membrane segments, which promotes elongation of the invagination into a tubule. Scission occurs on average 9 s after initial bending when invaginations are ∼100 nm deep, releasing nonspherical vesicles with 6,400 nm2 mean surface area. Direct correlation of protein dynamics with ultrastructure provides a quantitative 4D resource.