The heparan sulphate proteoglycan agrin is well known as the key assembly factor of postsynaptic differentiation at the neuromuscular junction (NMJ), but recent data suggest it also plays a direct role in the organization of the cytoskeleton in the skeletal muscle. Signaling through muscle-specific proteins such as muscle specific kinase (MuSK) and or acetylcholine receptor (AchRs)/rapsyn, agrin can activate ubiquitously expressed Rac, Cdc42, and p21-activated kinase (PAK) that are involved in actin polymerization. Agrin also engages signaling pathways of several potent oncogenes (i.e., SFK, ErbB receptors, and cortactin).

Contributor: Kosi Gramatikoff, PhD

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