Background of the antigen
The Testican family, also designated the BM-40/SPARC/osteonectin family, is composed of highly conserved, extracellular, calcium-binding, sulfate proteoglycans. Expression of Testicans is detected in a variety of tissues, but is most abundant in brain. Family members include Testican-1, Testican-2, Testican-3 and an amino-terminal splice variant of Testican-3, designated N-Tes. Most Testicans inhibit MT-MMPs, thereby inhibiting the activity of pro-MMP-2. Testican-1 is specifically expressed in the thalamus of the brain, and is upregulated in activated astroglial cells of the cerebrum where it mediates neuronal attachment and matrix metalloproteinase activation. After a neural injury, such as a cerebral stroke, Testican-1 expression is upregulated in astrocyte cells in order to inhibit the ability of the protein Neuro-2a to form neurite extensions. Testican-1 is also a component of joint and of the growth plate cartilage that may participate in the regulation of matrix turnover.
