Characterization and enrichment of erase, a serine proteinase that collapses CNS growth cones
Retinal growth cones that encounter peripheral neurites in culture undergo a dramatic change in morphology. Extension of lamellae and filopodia ceases and the lamellae collapse inward towards the central region of the growth cone (Kapfhammer and Raper, 1987. J. Neurosci. 7, 201). Growth cone collapse prevents retinal neurites from crossing over or fasciculating along peripheral axons displaying this avoidance cue. A growth cone collapsing activity has been found in detergent extracts of adrenal plasma membranes that has characteristics expected for this peripheral axonal avoidance cue. It causes the collapse of retinal and other CNS derived growth cones but has little effect on peripherally derived growth cones. This collapsing activity induces the rapid and reversible collapse of retinal growth cones grown on either of two distinct adhesion substrata, mouse laminin or the chick axonal surface glycoprotein G4/NgCAM. The collapsing activity of the adrenal extract is inhibited by several different classes of serine proteinase inhibitors, including the irreversible inhibitor PPACK (D-Phenylalanyl-Prolyl-Arginine chloromethyl ketone). This adrenal derived growth cone collapsing proteinase has been named erase. The growth cone collapsing activity of erase is functionally and biochemically distinct from the neurite retracting activity of thrombin. The retinal growth cone collapsing activity of adrenal plasma membrane extracts is enriched approximately 2,000 fold by combination of anion exchange and affinity chromatography. SDS-PAGE analysis of the eluate from a three step purfication series reveals a candidate protein for erase migrating at 23kD with a specific activity of $\leq$430 pM. In the presence of PPACK, temporal retinal growth cones collapse less frequently when they contact dorsal root ganglia (DRG) axons of the peripheral nervous system. As a result, they cross DRG axons with little delay. In contrast, the presence of PPACK has no effect on temporal retinal growth cones that collapse in response to a distinct avoidance cue found on nasal retinal axons. These results support the hypothesis that a serine proteinase similar or identical to erase is the avoidance cue associated with peripheral axons which induces the contact mediated collapse of retinal ganglion cell growth cones.
Baird, Janet Lynn, "Characterization and enrichment of erase, a serine proteinase that collapses CNS growth cones" (1996). Dissertations available from ProQuest. AAI9627879.