PARIS - Researchers at France's National Institute for Health and Medical Research (Institut National de la Santi et de la Recherche Midicale, or INSERM) have discovered a hitherto unknown neuropeptide in man, urotensin II, which is expressed in the motoneurons of the spinal cord.
Urotensin II was originally identified in fish. But in 1992 the INSERM team, which is based in Rouen, northwest of Paris, and led by Hubert Vaudry, also discovered the peptide in the brain of a frog. This led the scientists to look for it in humans as well.
They started by reconstituting the sequence of the urotensin II gene using tissue from the frog, then compared it with a data bank of thousands of unknown genetic sequences. One of them, belonging to the human species, displayed a very close analogy with the urotensin II gene sequence in the frog, suggesting that the same gene existed in man as well.
The researchers then went on to sequence this gene and look for the sites where it was expressed in the human organism. They discovered that the gene coding for urotensin II is selectively expressed in certain neurons of the spinal cord, namely the motoneurons which govern the movements of the arms and legs. INSERM has since filed a patent application covering this discovery.
This is the second neuropeptide found to be preferentially expressed in motoneurons in man, the other one being CGRP. Vaudry's team thinks urotensin II could play an important role in neuromuscular transmission and now intends to study its expression specifically in neuromuscular diseases such as amyotrophic lateral sclerosis. - James Etheridge