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© The Rockefeller University Press,
0021-9525/2000//1295 $5.00
The Journal of Cell Biology, Volume 148, Number 6,
, 2000 1295-1304
Original Article |
The Tissue Plasminogen Activator (Tpa/Plasmin) Extracellular Proteolytic System Regulates Seizure-Induced Hippocampal Mossy Fiber Outgrowth through a Proteoglycan Substrate
stsirka{at}mail.psychiatry.sunysb.edu
Short seizure episodes are associated with remodeling of neuronal connections. One region where such reorganization occurs is the hippocampus, and in particular, the mossy fiber pathway. Using genetic and pharmacological approaches, we show here a critical role in vivo for tissue plasminogen activator (tPA), an extracellular protease that converts plasminogen to plasmin, to induce mossy fiber sprouting. We identify DSD-1-PG/phosphacan, an extracellular matrix component associated with neurite reorganization, as a physiological target of plasmin. Mice lacking tPA displayed decreased mossy fiber outgrowth and an aberrant band at the border of the supragranular region of the dentate gyrus that coincides with the deposition of unprocessed DSD-1-PG/phosphacan and excessive Timm-positive, mossy fiber termini. Plasminogen-deficient mice also exhibit the laminar band and DSD- 1-PG/phosphacan deposition, but mossy fiber outgrowth through the supragranular region is normal. These results demonstrate that tPA functions acutely, both through and independently of plasmin, to mediate mossy fiber reorganization.
Key Words: neurite dentate nonproteolytic kainic acid seizure
© 2000 The Rockefeller University Press
Abbreviations used in this paper: DG, dentate gyrus; ECM, extracellular matrix; GABA,
-aminobutyric acid; KA, kainic acid; LTP, long-term potentiation; NCAM, neural cell adhesion molecule; NMDA, N-methyl-D-aspartate; plg, plasminogen; plg–/–, plg deficient; PSA-NCAM, polysialylated NCAM; RPTP
/β, receptor-type transmembrane protein tyrosine phosphatase; tPA, tissue plasminogen activator; tPA–/–, tPA deficient.
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