 |
||||
|
||||
|
||||
|
|
||||||||||||||||
|
||||||||||||||||
|
MIGHTY MUSCULAR MICE CLONED By Sean Henahan, Access Excellence BALTIMORE, Md. (May 7, 1997) The development of genetically-engineered supermouse could lead to new treatments for muscular dystrophy and related diseases. Using gene 'knock-out'; techniques, researchers at Johns Hopkins were able to create healthy mice with two to three times normal muscle mass. "The first thing that we noticed was that the knockout mice had unusually large shoulders and hips," says Alexandra McPherron, a Hopkins Ph.D. student and first author of a paper in this week's Nature. "On closer analysis we found that all their muscles were two to three times normal size." To researchers "knocked out" a newly discovered gene called growth/differentiation factor 8 (GDF 8). The GDF 8 protein limits skeletal muscle growth. Lacking GDF 8, the mice's muscles grew dramatically. The GDF 8 genes were altered in mouse embryonic stem cells, which appear very early in a mouse's development before cell specialization occurs. When these cells produce egg or sperm cells in a mouse, the genetic changes were passed on to every cell of the mouse's descendants when they reproduced. Nearly a year after their initial creation, the mutant mice show no other signs of abnormality and can reproduce healthy offspring. A human form of GDF 8 has been identified. The Hopkins team will now investigate whether it performs the same function in humans. Early studies suggest the gene is only active appears in skeletal muscle tissue. This might explain which why removing it has had little effect beyond enlarging the mice's muscles. "Except for the muscles, the mice appear to be normal and healthy," says McPherron. "We're excited that GDF 8 could give us new opportunities to treat the many muscle-wasting diseases like muscular dystrophy or cachexia, the muscle loss that accompanies some cancers and AIDS," said Se-Jin Lee, M.D., Ph.D., an assistant professor of molecular biology and genetics. "We've also found GDF 8 in cows and chickens, so we might be able to interfere with it to create livestock with more meat and relatively less fat," says Lee. The Hopkins team found the gene by searching for new members of the transforming growth factor-beta (TGF-beta) gene family. Other TGF-beta genes include bone morphogenetic proteins, a group of genes that helps stimulate bone growth, and glial-derived neurotrophic factor, a gene that sustains nerve cells. Proteins from both of these groups are already in clinical trials for treatment of various disorders.
|
Science Updates Index| Today's Health and BioScience News |
Science Update Archives | Factoids | Newsmaker Interviews Archive |
 |
||
Custom Search
on the AE Site
|
||
 | ||||
| ||||
| ||||
|