Fibulin-5 for youthful skin

Fibul in-5 for youthful skin A loss of tissue elasticity leads to wrinkles and more serious age-related problems, such as emphysema and vascular defects. On page 1061, Hirai et al. report that youthful elastic fi bers are assembled by an extracellular matrix protein that slips away with age. Mice that lack this matrix protein, called fi bulin-5, have loose, wrinkled skin, vascular abnormalities, and emphysema, all of which are thought to be due to their disorganized and fragmented elastic fi bers. Elastic fi bers are composed of an inner core of cross-linked elastin surrounded by a microfi bril envelope. Hirai et al. now show that fi bulin-5 generates elastic fi bers by promoting aggregation of the elastin precursor, called tropoelastin, its deposition onto microfi brils, and its cross-linking into mature elastin. A naturally occurring truncated version of fi bulin-5 that did not associate with microfi brils was unable to promote elastic fi ber assembly. This truncated version accumulated with age, while the full-length, microfi bril-associating version diminished. The shorter version of fi bulin-5 is formed by the action of a serine protease, which cleaves off the NH 2 -terminal region of the full-length protein. The team is currently investigating the identity of this protease and trying to determine why it promotes more cleavage with age.