Abstract
Agrin is a heparan sulfate proteoglycan, which plays an essential role in the development and maintenance of the neuromuscular junction. Agrin is a stable component of the synaptic basal lamina and strong evidence supports the hypothesis that agrin directs the formation of the postsynaptic apparatus, including aggregates of AChRs, and junctional folds. Changes in the distribution of agrin during synaptic remodeling, denervation and reinnervation reveal that agrin can be quickly and efficiently removed from the synaptic basal lamina in a regulated manner. In order to fully understand this mechanism we sought to identify those molecules that were responsible for the removal of agrin. Matrix Metalloproteinases (MMPs) were the most likely molecules since MMPs are involved in the regulation of the pericellular space, including the cleavage of matrix proteins. In particular, MMP3 has been shown to be effective in cleaving heparan sulfate proteoglycans. Antibodies to MMP3 recognize molecules concentrated in the extracellular matrix of perisynaptic Schwann cells. MMP3 specific phylogenic compounds reveal that active MMP3 is localized to the neuromuscular junction. Purified recombinant MMP3 can directly cleave agrin, and it can also remove agrin from synaptic basal lamina. MMP3 activity is itself regulated as activation of MMP3 is lost in denervated muscles. MMP3 null mutant mice have altered neuromuscular junction structure and function, with increased AChRs, junctional folds and agrin immunoreactivity. Altogether these results support the hypothesis that synaptic activity induces the activation of MMP3, and the activated MMP3 removes agrin from the synaptic basal lamina.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 905-913 |
| Number of pages | 9 |
| Journal | Journal of Neurocytology |
| Volume | 32 |
| Issue number | 5-8 |
| DOIs | |
| State | Published - Jun 2003 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Cell Biology
- Anatomy
- Histology
- Neuroscience(all)
Cite this
Activity dependent removal of agrin from synaptic basal lamina by matrix metalloproteinase 3. / Werle, Michael J.; Vansaun, Michael.
In: Journal of Neurocytology, Vol. 32, No. 5-8, 06.2003, p. 905-913.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Activity dependent removal of agrin from synaptic basal lamina by matrix metalloproteinase 3
AU - Werle, Michael J.
AU - Vansaun, Michael
PY - 2003/6
Y1 - 2003/6
N2 - Agrin is a heparan sulfate proteoglycan, which plays an essential role in the development and maintenance of the neuromuscular junction. Agrin is a stable component of the synaptic basal lamina and strong evidence supports the hypothesis that agrin directs the formation of the postsynaptic apparatus, including aggregates of AChRs, and junctional folds. Changes in the distribution of agrin during synaptic remodeling, denervation and reinnervation reveal that agrin can be quickly and efficiently removed from the synaptic basal lamina in a regulated manner. In order to fully understand this mechanism we sought to identify those molecules that were responsible for the removal of agrin. Matrix Metalloproteinases (MMPs) were the most likely molecules since MMPs are involved in the regulation of the pericellular space, including the cleavage of matrix proteins. In particular, MMP3 has been shown to be effective in cleaving heparan sulfate proteoglycans. Antibodies to MMP3 recognize molecules concentrated in the extracellular matrix of perisynaptic Schwann cells. MMP3 specific phylogenic compounds reveal that active MMP3 is localized to the neuromuscular junction. Purified recombinant MMP3 can directly cleave agrin, and it can also remove agrin from synaptic basal lamina. MMP3 activity is itself regulated as activation of MMP3 is lost in denervated muscles. MMP3 null mutant mice have altered neuromuscular junction structure and function, with increased AChRs, junctional folds and agrin immunoreactivity. Altogether these results support the hypothesis that synaptic activity induces the activation of MMP3, and the activated MMP3 removes agrin from the synaptic basal lamina.
AB - Agrin is a heparan sulfate proteoglycan, which plays an essential role in the development and maintenance of the neuromuscular junction. Agrin is a stable component of the synaptic basal lamina and strong evidence supports the hypothesis that agrin directs the formation of the postsynaptic apparatus, including aggregates of AChRs, and junctional folds. Changes in the distribution of agrin during synaptic remodeling, denervation and reinnervation reveal that agrin can be quickly and efficiently removed from the synaptic basal lamina in a regulated manner. In order to fully understand this mechanism we sought to identify those molecules that were responsible for the removal of agrin. Matrix Metalloproteinases (MMPs) were the most likely molecules since MMPs are involved in the regulation of the pericellular space, including the cleavage of matrix proteins. In particular, MMP3 has been shown to be effective in cleaving heparan sulfate proteoglycans. Antibodies to MMP3 recognize molecules concentrated in the extracellular matrix of perisynaptic Schwann cells. MMP3 specific phylogenic compounds reveal that active MMP3 is localized to the neuromuscular junction. Purified recombinant MMP3 can directly cleave agrin, and it can also remove agrin from synaptic basal lamina. MMP3 activity is itself regulated as activation of MMP3 is lost in denervated muscles. MMP3 null mutant mice have altered neuromuscular junction structure and function, with increased AChRs, junctional folds and agrin immunoreactivity. Altogether these results support the hypothesis that synaptic activity induces the activation of MMP3, and the activated MMP3 removes agrin from the synaptic basal lamina.
UR - http://www.scopus.com/inward/record.url?scp=3042576001&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=3042576001&partnerID=8YFLogxK
U2 - 10.1023/B:NEUR.0000020631.69804.f5
DO - 10.1023/B:NEUR.0000020631.69804.f5
M3 - Article
C2 - 15034275
AN - SCOPUS:3042576001
VL - 32
SP - 905
EP - 913
JO - Journal of Neurocytology
JF - Journal of Neurocytology
SN - 0300-4864
IS - 5-8
ER -