纤毛：小细胞器，大的决定

霍普金斯大学的研究人员说，他们已经找到了人类和所有动物的细胞调整到一个重要的信号，一个是发送形状最终机构的指示。它把细胞组装成自己的小收音机天线在他们的表面上，以帮助他们中继正确的信号，发育蛋白“听”的内部的细胞。

发射机是初级纤毛，相对刚性的，毛茸茸的“尾巴”，响应来自主机的蛋白质专门的信号，包括蛋白质被称作Wnts关键家庭。反过来，已引发一系列形状的决策，引导细胞以特定的形状，如弯曲的眼睑细胞或振动的毛细胞的耳朵，甚至让手臂和腿出现在正确的位置上。 

“我们的实验去我们身体的组织开发和维护的心，说：”霍普金斯大学的遗传学家尼古拉斯Katsanis，博士，在遗传医学麦库西克-内森斯研究所副教授。“与Wnt信号通路的任何失误，”Katsanis说道，“你看主要的儿童疾病和缺陷。” 

在9月30日发表的一份报告中自然遗传学， Katsanis and his team used a small transparent fish， zebrafish， to literally watch what happened if they chemically blocked the production of three proteins that are required for primary cilia function during the period when a fish egg develops into a grown up， fully-finned fish.

The more they blocked， the more developmental errors - for example， the growing fish would not properly extend their tails - they were able to track to defective Wnt signaling.

Katsanis notes that once inside a cell， the Wnt pathway splits into two branches that need to be balanced depending on the needs of each cell: the so-called canonical branch， which typically drives cells to multiply， and the non-canonical branch， which controls messages to refine cell shape and growth.  The errors seen in the fish pointed to an imbalance where canonical signaling predominated.

A series of biochemical studies revealed that cilia normally help a cell keep the right balance by selectively destroying proteins in the canonical branch to prevent excess growth. Defective ciliary function therefore leads to defective destruction of key proteins， which then causes problems in interpreting the Wnt signal.  

“We thought that the key to the balancing act occurred inside the cell， but it now seems clear that the cilia are the main relay stations，” Katsanis says. “We’ve just reset a huge volume of literature under a new light.”

The research was funded by the National Institute of Child Health and Development， the National Institute of Diabetes， Digestive and Kidney Disorders， the National Institute for Arthritis and Musculoskeletal Disorders， the German Academic Exchange Service， and the Medical Research Council.

Authors on the paper are Philip Beachy of Stanford School of Medicine; Philip Beales of University College London; George DeMartino from UT Southwestern; and Jantje M. Gerdes， Norann Zaghloul， Carmen Leitch， Shaneka S. Lawson， Masaki Kato， Shannon Fisher and Katsanis of Johns Hopkins.

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