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Implication of geranylgeranyltransferase I in synapse formation
Zhen G Luo1, Hyun-Soo Je, Qiang Wang
1Department of Neurobiology, Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Neuron
|November 19, 2003
Summary
Geranylgeranyltransferase I (GGT) is crucial for acetylcholine receptor (AChR) clustering at the neuromuscular junction (NMJ). This study reveals GGT
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Agrin signaling activates MuSK kinase to cluster acetylcholine receptors (AChR) at the neuromuscular junction (NMJ).
- The intracellular signaling pathways downstream of MuSK remain incompletely understood.
Purpose of the Study:
- To investigate the role of geranylgeranyltransferase I (GGT) in the Agrin/MuSK signaling pathway.
- To elucidate the contribution of GGT to AChR clustering and neuromuscular synapse formation.
Main Methods:
- Assessed tyrosine phosphorylation and activity of GGT's alpha(G/F) subunit upon Agrin stimulation.
- Utilized GGT inhibition (activity or expression) in muscle cells and spinal neuron-muscle cocultures.
- Examined neuromuscular junction (NMJ) morphology in transgenic mice expressing a mutant alpha(G/F) subunit.
Main Results:
- Agrin stimulation rapidly increased alpha(G/F) subunit tyrosine phosphorylation and GGT activity.
- Inhibition of GGT impaired Agrin-induced AChR clustering and attenuated synapse formation.
- Transgenic mice with mutant alpha(G/F) exhibited NMJ defects, including wider endplate bands and smaller AChR plaques.
Conclusions:
- Geranylgeranyltransferase I (GGT) is an essential signaling component in the Agrin/MuSK pathway.
- Prenylation mediated by GGT is necessary for AChR clustering and neuromuscular junction formation/maintenance.
- This study highlights a novel role for GGT in regulating neuromuscular synapse development.