Architects of the envelope
核膜建筑师
Scientists discover an essential nucleus-building protein
科学家发现了一种基本的细胞核建筑蛋白
Every time a cell divides, the protective envelope that surrounds the nucleus is broken down and rebuilt into two new ones. Envelopes are highly complex structures of membranes and proteins which must be precisely reassembled for the nuclei to function. Scientists at the Institute for Research in Biomedicine (IR in Barcelona, the European Molecular Biology Laboratory (EMBL) in Heidelberg and the Pasteur Institute in Paris have discovered a protein that plays a crucial role in the assembly and structure of the nucleus. Their work appears in the September 5 issue of Current Biology.
每次当一个细胞分裂时，包被在细胞核外起保护作用的核膜都会崩解，重新建出两个新的来。核膜是一个高度复杂的膜结构。为了细胞核能正常行使功能，蛋白质必须精细地结合在一起。巴塞罗那的生物医学研究所，海德堡的欧洲分子生物学实验室和巴黎的巴斯德研究所发现了一种蛋白在核装配与核结构方面扮演了重要角色。他们的工作发表在今年9月5日的《Current Biology》上。
The envelope acts as a barrier between the outer cell compartment, called the cytoplasm, and DNA stored in the cell nucleus. It regulates which molecules are allowed to pass back and forth between the two compartments. Most of this traffic passes through basket-shaped passageways called nuclear pores, which consist of intricately-woven proteins. "We haven't yet identified all the molecules in the nuclear envelope, and many questions remain about the process by which molecules are granted or denied passage," says Peter Askjaer of IRB.
核膜是细胞外部区室细胞质与内部区室细胞核（DNA储藏地）之间的屏障，调节着来往于两个区室的分子。大多数这样的来往都要通过一些篮筐状的通道，名为核孔。核孔包括一些杂乱编织在一起的蛋白。“我们还没有鉴定出核膜上所有的成员，是否允许一些分子进出细胞核，还有很多问题没有解决。”巴塞罗那生物医学研究所的Peter Askjaer这样说道。
The new study shows that a protein called MEL-28 is a component of nuclear pores in the worm C. elegans, one of biology's most important model organisms. More importantly, it reveals that MEL-28 is one of the key architects as bits of membrane and proteins are drawn together to build new envelopes.
这项新的研究表明在其中一种最重要的模式生物秀丽线虫中，一个名为MEL-28的蛋白是核孔的一个成员。更重要的是它揭示了MEL-28是其中一名关键的建筑师，它把小块儿的膜以及蛋白“缝合”在一起，来建造一个新的核膜。
When scientists blocked the activity of MEL-28, they discovered that patches of membranes attached themselves to DNA but couldn't seal themselves off into a complete envelope. A step-by-step analysis showed that without the protein, other molecules are not drawn together properly as envelopes are rebuilt. The components were scrambled; pores were no longer built, and the wrong molecules were able to get access to DNA. Because MEL-28 remains attached to DNA during the entire process of cell division, the scientists believe it plays a crucial role early in the formation of the envelope.
当科学家们封闭了MEL-28的功能后，他们发现这些小块儿的膜与DNA粘附在一起，但并不能使自身密封成一个完整的膜。逐步分析表明没有这种蛋白，其他分子便不能正确的结合在一起完成膜的重建。这些组分被干扰后，核孔就不能再形成，而后错误的分子便可与DNA结合。由于MEL-28蛋白在整个细胞分裂的过程中一直与DNA粘附在一起，科学见因此相信它在核膜形成的早期扮演了关键的角色。
MEL-28 has a close relative in human cells; one of the researchers' future projects will be to examine whether this molecule plays a similar role in our own species. Oddly-shaped nuclear envelopes are seen in human genetic diseases such as progeria, a rare condition that causes affected children to age prematurely, and some types of muscular dystrophies. "Understanding how the nuclear envelope forms in the first place may eventually help us understand how changes in it can cause these diseases and potentially how they can be treated," says Askjaer
在人类细胞中MEL-28有一个近亲，这是研究者以后将要研究的课题之一，他们要探讨一下是否在人体内这个分子也起了相似的作用。有一种名为儿童早衰症的罕见疾病，导致儿童的早熟，以及一些肌肉的营养失调。这这种人类遗传性疾病中，核膜的外形非常古怪。Askjaer 说：“首先了解了核膜是怎样形成的，这一点最终有助于我们理解它是如何改变以及导致这些疾病的，还可能让我们理解这些疾病怎样得到治疗。”
