Fast controlling axis specification

Following fertilization, the first cell of a developing organism is essentially ‘round-’, or in other words, has no polarity--. Shortly afterwards, three axes are established: anterior-posterior (front to back), dorsal-ventral (top to bottom) and left-right. As a result, we develop a chest and back, a head and feet, etc. Previous research has shown that several genes are involved in setting up polarity in all three dimensions, but that in addition, many genes have very specific effects.

For example, a particular gene might be essential for setting up the anterior-posterior axis but it might not have any effects on the dorsal-ventral axis. As with many developmental processes, transcription factors - genes that directly turn on other sets of genes - are key players in axis specification. One such gene is FoxH1. FoxH1 has been proposed as a candidate mediator of axis specification.

Only recently has the definitive test of FoxH1’s function been performed. Two independent research groups, led by Dr. Hiroshi Hamada of Osaka University in Japan and Dr. Jeff Wrana of the Samuel Lunenfeld Research Institute in Toronto, have inactivated the FoxH1 gene in mice. As published in G&D, both groups found that the lack of functional FoxH1 had a profound effect on axis specification. In many cases, the developing mouse embryos could not specify the anterior–posterior axis. In some cases, the embryos could establish the anterior-posterior axis, but later developmental steps were defective. This work establishes FoxH1 as an essential gene for anterior-posterior axis specification, and suggests a number of candidate genes with which FoxH1 may interact.