Hox Gene - History

History

Christiane Nüsslein-Volhard and Eric F. Wieschaus identified and classified 15 genes of key importance in determining the body plan and the formation of body segments of the fruit fly Drosophila melanogaster. In the late 1940s, Edward B. Lewis studied the Hox genes, which specify the identity of each segment after they are formed. Incorrect expression of Hox genes can lead to major changes in the morphology of the individual, called homeotic transformations, where one segment develops into the likeness of another. A famous example in Drosophila melanogaster is the mutation of the Ultrabithorax Hox gene, which specifies the 3rd thoracic segment. Normally, this segment displays a pair of legs and a pair of halteres (a reduced pair of wings used for balancing). In the mutant lacking functional Ultrabithorax protein, the 3rd thoracic segment now expresses the same structures found on the segment to its immediate anterior, the 2nd thoracic segment, which contains a pair of legs and a pair of (fully developed) wings. These mutants sometimes occur in wild populations of flies, and it was these mutants that led to the discovery of Hox genes.

For their work, Nüsslein-Volhard, Wieschaus, and Lewis were awarded the Nobel Prize in Physiology or Medicine in 1995.

In 1983, the homeobox was discovered independently by researchers in two labs: Ernst Hafen, Michael Levine, and William McGinnis (in Walter Gehring's lab at the University of Basel, Switzerland) and Matthew P. Scott and Amy Weiner (in Thomas Kaufman's lab at Indiana University in Bloomington).