Along with the miracle of life comes the miracle of an expanding uterus. The organ, which enlarges from the size of a pear to bigger than a basketball during the nine months of pregnancy, is the most obvious example of the bodys elastic fibers at work. Now researchers have identified the enzyme responsible for this resiliency, a finding that could point the way to new ways of fighting aging and disease.

The bodys elastic fibers form when a protein known as tropoelastin is polymerized. The reaction employs a chemical called lysyl oxidase (LOX) as a catalyst. Mammals can produce up to five types of LOX proteins as well as some LOX-like ones. Tiansen Li of Harvard Medical School and his colleagues genetically engineered mice that lacked the LOXL1 enzyme to investigate its effects on elasticity. They found that animals that lacked the protein had loose and baggy skin much too large for their bodies. In addition, the females suffered higher rates of pelvic prolapse, a condition in which the womb does not recover properly after giving birth.

The scientists determined that LOXL1 is active in a number of other organs that experience stretching as well, including the lungs, stomach, bladder and blood vessels. The protein is crucial to generating reinforcing cross-links between elastic fibers and plays a role in determining where elastic fibers will be placed, the team reports online this week in Nature Genetics. Because loss of elastic fibers underlies tissue aging and diseases such as emphysema, the results could suggest a novel target for treatment.