Scientists discover new and unexpected features of collagen -
WHAT: Scientists from the National Institutes of Health show unexpected new details about the fundamental structure of collagen, the most abundant protein in the human body. In laboratory experiments, they showed that collagen once considered inert forms structures that regulate how certain enzymes decompose and reshape the body tissues. The discovery of this regulatory system provides a molecular view of the potential role of physical forces at work in heart disease, cancer, arthritis, and other processes related to the disease, they say. The study appears in the current online issue of Proceedings of the National Academy of Sciences .
Scientists have known for years that collagen remodeling plays an important role in a variety of biological processes ranging from wound healing to cancer growth. In particular, researchers know that collagen is broken down by a certain class of enzymes called matrix metalloproteinases (MMPs), but exactly how they did it remained somewhat of a mystery, until now.
In the NIH study, the scientists isolated individual, collagen fibrils of nanoscale rat tail tendons. They then exposed the fluorescence labeled collagen fibrils human MMP enzymes. Using video microscopy, scientists have followed thousands of enzymes that move along a fibril. Unexpectedly, the scientists observed that the enzymes have preferred to fix in some places along the fibrils, and over time these binding sites moved slowly, or disappeared and reappeared in other positions. These observations revealed collagen fibrils have defects that form spontaneously and heal. In the presence of voltage, such as tendons stretching, defects are probably eliminated, which prevents collagen decomposition enzyme which is responsible for the physical strength, the researchers suggest. In short, they have identified a possible mechanism of the sensitive strain to regulate tissue remodeling.
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