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"The common thinking is that atrial fibrillation is an electrical problem of the heart," said Qing Kenneth Wang of the Cleveland Clinic. That has led to the notion that ion channels are primarily responsible since they control the electrical impulses that keep the heart beating.

参考翻译：Cleveland Clinc 的Qing Kenneth Wang说：“通常认识是房颤属于心脏电生理问题”于是就导致了一个概念离子通道异常是导致房颤的主要原因，因为它控制了保证心跳的电冲动。

Wang's team now shows that defects in a gene known as NUP155, a key component of the so-called nuclear pore complex, also leads to arrhythmia in patients with two abnormal copies of the gene. "It's unexpected," he said. "We never thought a gene like this could lead to atrial fibrillation."

参考翻译：wang的研究小组说NUP155基因是所谓的细胞核微孔复合物的重要组成部分，它的缺陷，只要有两个片段的基因异常就可以引起心律失常。Wang说：“这真是出乎意料，我们从来没有想过这样的一个基因可以引起房颤。”

Atrial fibrillation is characterized by uncoordinated beating of the hearts upper chambers. The heartbeat in patients with atrial fibrillation is not only uncoordinated, Wang said, but also very chaotic and rapid. Whereas a normal heart beats 70 or 80 times a minute, in atrial fibrillation that rate can jump to 300 beats per minute. As the population ages, the incidence of the disease is rising in step and atrial fibrillation is now responsible for an estimated 15 percent of all strokes.

参考翻译：房颤是以心脏高位心腔运动不协调为特征。Wang说房颤病人的不仅是不协调，而且非常混乱而且快。房颤时候心率可以达到每分钟300次，但是正常心跳每分钟不过70~80次，随着年龄的增加，房颤的发生几率逐步上升，据统计15%的中风是由房颤引起。

In most people, the disease stems from a complex interplay of genetic and environmental causes. In some 30 percent, however, the disease is tied directly to single genes that are passed down over generations, spurring disease in some cases with a single abnormal copy and in others only in those with two defective variants. In a handful of families, those rare genes have been linked to ion channels, but in many cases the function of the genes responsible remains a mystery.

参考翻译：在大多数人，这一疾病是由基因和环境因素相互的复杂作用引起。尽管如此，大约30%的疾病是直接由单个基因决定，这个基因一代一代下传。在少数家庭，这些稀有的基因已经和离子通道相关联，但是在许多病例里这些基因的作用仍然是个谜。

Wang's team had earlier traced the gene responsible for atrial fibrillation in one family to a region on chromosome 5. Family members with two copies of the offending variant develop symptoms of the disease and can suffer sudden death in early childhood. They now find that the root cause is NUP155.

参考翻译：Wang的研究小组早先在一个家庭里追踪了引起房颤的基因，一直追踪到了5号染色体的一个区域。家庭成员只要有了两个拷贝的变异出现症状就可能导致夭折。现在他们找到这个根本原因就在于基因NUP155。

To further work out what the NUP155 gene does in the new study, the researchers studied mice with the mutation. Mice with two defective copies of NUP155 die very early, but those with only one copy live and show signs of atrial fibrillation. The nuclear pore complex that includes NUP155 is responsible for the transport of many proteins and messenger RNAs (mRNAs) transcribed from DNA in and out of the cell nucleus. Once transported out of the nucleus, mRNA is translated into proteins that do the work of the cell, and Wang's team finds that loss of fully functional NUP155 causes a particular problem in moving the mRNA that encodes a gene known as heat shock protein 70 (Hsp70) out of the cell nucleus and in moving the Hsp70 protein back in.

参考翻译：为了在新的研究中知道NUP155是什么，研究人员选取了变异老鼠作为研究对象。有两个拷贝NUP155基因缺陷的很快死亡，但是那些只有一个拷贝缺陷的存活下来并表现出房颤。细胞核微孔复合体包含了NUP155，它与许多蛋白转运和信使RNA从DNA转录信息到细胞外有关。一旦转运出细胞核，mRNA被翻译为功能蛋白，Wang的小组发现丢失了完全功能的NUP155会引一个问题，那就是起编码热休克蛋白70出细胞核的mRNA和热休克蛋白70回到细胞内的转运障碍。

"Hsp70 has an important role in protecting the heart from stress damage," Wang said. "We think when NUP155 is mutated it leads to a decline in expression of Hsp70 and the heart is unprotected from damages. That may be why people develop atrial fibrillation."

参考翻译：“热休克蛋白70在保护心脏免于压力引起的损伤中起了重要作用，”wang说，“我们认为当NUP155发生变异将引起热休克蛋白70的表达减少，那么心脏就失去了保护。那可能就是人们出现房颤的原因。”

NUP155 likely controls the movement of many other molecules as well, he added. If those responsible for atrial fibrillation can be found, NUP155 itself along with any of those important downstream genes it effects may make potentially good targets for drugs designed to combat atrial fibrillation. The molecular identification of NUP155 as an atrial fibrillation gene may also facilitate the development of new diagnostic tools for catching the disease early and perhaps even preventing it, the researchers said.

参考翻译：他补充到，NUP155好像也控制着其他分子的运动。

While the specific mutation in NUP155 Wang's team studied is rare, he nevertheless suspects the newly identified mechanism could play a role in other cases of the disease as well. For one thing, mice develop atrial fibrillation with just one copy of the gene, suggesting that people carrying a single mutant copy or variants of the gene with more subtle effects might also be more susceptible to the disease. "It may be a more common cause of the disease than we realize," he said.

翻译待续...