Cell Biology

More Power to Your Arm

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Science  13 Jul 2001:
Vol. 293, Issue 5528, pp. 175
DOI: 10.1126/science.293.5528.175b

At the neuromuscular junction, nerves and muscle interact and clusters of muscle acetylcholine receptors (AChRs) form in association with neuronal agrin. Using purified recombinant chick agrin derived either from muscle or from neurons, Bezakova et al. have demonstrated a specific ability of neural agrin to promote long-lived AchR clustering, when injected into rat soleus muscle. The injected agrin could be recovered from the muscles in association with the extracellular matrix protein laminin. In a separate study, Bezakova and Lømo went on to show that muscle agrin helped to preserve costameric structures (small riblike structures composed of dystrophin and β-dystroglycan across the muscle Z and M lines) in the absence of muscular stimulation. Usually these structures would reorient longitudinally after denervation. This unanticipated lability in costamere structure in response to stimuli, and the differential ability of muscle and nerve agrins to induce stable AChR clusters, may be important in the muscular dystrophies. — SMH

J. Cell Biol.153, 1441;1453 (2001).

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