MicroRNAs in early patterning - The Scientist - Magazine of the Life Sciences
Abstract
MicroRNAs influence crucial decisions in the patterning of the early vertebrate embryo, reports a study online this week in Nature. The study is the first example of microRNAs regulating a fundamental signaling cascade, the authors say. "It's an important finding," said Deepak Srivastava of the University of California, San Francisco, because it demonstrates that "microRNAs can play such a fundamental role in embryonic patterning." Srivastava was not involved in the study. According to senior author Stefano Piccolo of the University of Padua in Italy, the finding also provides "a solution to a long-standing issue in vertebrate embryology." This issue revolves around how the basic body plan is set up in a developing embryo. When a vertebrate egg is fertilized, the site of sperm entry establishes the future dorsal/ventral axis of the embryo by driving ￢-catenin signaling on the dorsal side. The ￢-catenin signals are eventually translated into a gradient of another signaling molecule called Nodal. High Nodal expression on the dorsal side of the embryo induces a set of cells called the Spemann organizer, which establishes major parts of the animal's body pattern. But researchers have not known how the ￢-catenin pathway and the Nodal pathway communicate with