Activation of matrix metalloproteinase‐3 is altered at the frog neuromuscular junction following changes in synaptic activity

The extracellular matrix surrounding the neuromuscular junction is a highly specialized and dynamic structure. Matrix metalloproteinases are enzymes that sculpt the extracellular matrix. Since synaptic activity is critical to the structure and function of this synapse, we investigated whether change...

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Published in:	Developmental neurobiology (Hoboken, N.J.) Vol. 67; no. 11; pp. 1488 - 1497
Main Authors:	VanSaun, M., Humburg, B.C., Arnett, M.G., Pence, M., Werle, M.J.
Format:	Journal Article
Language:	English
Published:	Hoboken Wiley Subscription Services, Inc., A Wiley Company 15-09-2007
Subjects:	agrin Animals Anura Enzyme Activation - physiology Extracellular Matrix - metabolism Fluorescent Dyes M2300 Matrix Metalloproteinase 3 - metabolism Neuromuscular Junction - cytology Neuromuscular Junction - drug effects Neuromuscular Junction - enzymology Neuronal Plasticity - physiology Rana pipiens - anatomy & histology Rana pipiens - physiology Schwann Cells - enzymology Sodium Channel Blockers - pharmacology sprouting Staining and Labeling - methods stromelysin synaptic plasticity Synaptic Transmission - drug effects Synaptic Transmission - physiology Tetrodotoxin - pharmacology
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Summary:	The extracellular matrix surrounding the neuromuscular junction is a highly specialized and dynamic structure. Matrix metalloproteinases are enzymes that sculpt the extracellular matrix. Since synaptic activity is critical to the structure and function of this synapse, we investigated whether changes in synaptic activity levels could alter the activity of Matrix Metalloproteinases at the neuromuscular junction. In particular, we focused on Matrix Metalloproteinase 3 (MMP3), since antibodies to MMP3 recognize molecules at the frog neuromuscular junction, and MMP3 cleaves a number of synaptic basal lamina molecules, including agrin. Here we show that the fluorogenic compound (M2300) can be used to perform in vivo proteolytic imaging of the frog neuromuscular junction to directly measure the activity state of MMP3. Application of this compound reveals that active MMP3 is concentrated at the normal frog neuromuscular junction, and is tightly associated with the terminal Schwann cell. Blocking presynaptic activity via denervation, or TTX nerve blockade, results in a decreased level of active MMP3 at the neuromuscular junction. The loss of active MMP3 at the neuromuscular junction in denervated muscles can result from decreased activation of pro‐MMP3, or it could result from increased inhibition of MMP3. These results support the hypothesis that changes in synaptic activity can alter the level of active MMP3 at the neuromuscular junction. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1932-8451 1932-846X
DOI:	10.1002/dneu.20523