Matrix metalloproteinase production in regenerating axolotl spinal cord

Abstract

In urodele amphibian spinal cord regeneration, the ependymal cells lining the central canal remodel the lesion site to favor axonal regrowth. We profiled the production of matrix metalloproteinases by injury-reactive mesenchymal ependymal cells in vivo and in vitro and found that matrix metalloproteinases are involved in this remodeling process in the axolotl (Ambystoma mexicanum). The production of cell-associated matrix metalloproteinases in vivo was shown to be identical to that in our cultured ependymal cell model system. Activated and zymogen forms of matrix metalloproteinases were identified using zymography, chemical inhibitors of matrix metalloproteinases, and cleavage of propeptides by organomercurials. The principal cellular proteinases consisted of matrix metalloproteinase-2 (gelatinase A) and matrix metalloproteinase-1 (type I collagenase), which display characteristic shifts in molecular weight following proenzyme processing by organomercurials. In addition, ependymal cell conditioned medium contained secreted forms of the enzyme undetectable in situ. Matrix metalloproteinase-9 (gelatinase B) as well as matrix metalloproteinase-2 and matrix metalloproteinase-1 were secreted and casein substrate zymography showed the presence of a small amount of a very high molecular weight matrix metalloproteinase-3 (prostromelysin) secreted into the culture medium. Matrix metalloproteinases were still present at 4 weeks post-lesioning when the ependymal cells have just re-epithelialized, but decreased near the completion of regeneration (8 weeks post-lesioning). Zymography showed no detectable matrix metalloproteinases in unlesioned cord but the presence of tissue inhibitor of metalloproteinase-1 in intact cord was seen by Western blotting. This study shows that matrix metalloproteinases are associated with urodele spinal cord regeneration and validates the use of our ependymal cell tissue culture model system to evaluate ependymal cell behavior during spinal cord regeneration.

Robust axonal growth and a blunted macrophage response are associated with impaired functional recovery after spinal cord injury in the MRL/MpJ mouse

“…The MRL/MpJ mouse has a heightened and prolonged local expression of MMPs, including both MMP-2 and MMP-9, following ear punch or after injury to the cortex or retina in the CNS (Gourevitch et al, 2003; Hampton et al, 2004; Tucker et al, 2008). MMPs are important mediators of tissue regeneration in urodeles (Chernoff et al, 2000; Monaghan et al, 2007), yet their functions after injury in the mammalian CNS are complex. MMP-9 is upregulated at 1–2 days after SCI, during the period of neutrophil recruitment and tissue degradation (Noble et al, 2002; Goussev et al, 2003; Fleming et al, 2006).…”

Protease Regulation: The Yin and Yang of Neural Development and Disease

“…Many studies have demonstrated that MMPs facilitate axonal regeneration in the mammalian PNS (Heine et al, 2004; Kobayashi et al, 2008; Shubayev and Myers, 2004; Zuo et al, 1998), and the CNS of lower vertebrates (Chernoff et al, 2000). Researchers also found that increased MMP expression after mammalian CNS injury is correlated with areas of increased axonal outgrowth and the subsequent enhancement of functional recovery (Ahmed et al, 2005; Duchossoy et al, 2001; Hsu et al, 2006).…”

The Role of the Brain Extracellular Matrix in Synaptic Plasticity After Brain Injuries (Review)

“…After initial stage of trauma, when cell death, axon damage and demyelination are taking place, the glial scar starts developing [5,75]. Following, the production of ECM molecules increases at the damage [76,77]. Then activation and migration to the damage site of microglia occur, where they serve microphage function, particularly by removing disturbed myelin [78].…”