Brevican, a member of the lectican family, is one of the most abundant proteoglycans in normal adult brain tissues. It is thought to form lattice structures by linking hyaluronan and tenascin-R through its N- and C-terminal globular domains, respectively. As brain extracellular matrix (ECM) contains no collagen fibrils, this matrix of hyaluronan/brevican/tenascin-R is considered essential to maintain the integrity of brain ECM. Degradation of brevican by proteinases disrupts ECM structures and facilitates invasion of glioma cells (Yamaguchi 2000).
The major brevican cleavage site observed under physiological conditions (Yamada et al. 1994) and during glioma invasion (Zhang et al. 1998) is the Glu395-Ser396 bond present within the central domain of the core protein, forming an ~50-kDa N-terminal fragment. This bond is cleaved by ADAMTS4 and 5 (Nakamura et al. 2000, Matthews et al. 2000, Nakada et al. 2005). Matrix metalloproteinases that digest brevican (MMP-1, -2, -3, -7, -8, -10, -13 and -19) preferentially cleave the Ala360-Phe361 bond. (Nakamura et al. 2000, Nakada et al. 2005, Lettau et al. 2010).