Muscular Dystrophy Research Today is a free monthly online journal that collates and summarizes the latest research about Muscular Dystrophy, including details on duchenne muscular dystrophy, symptoms, treatment.

Calpain 3 is a modulator of the dysferlin protein complex in skeletal muscle.

Huang Y, de Morrée A, van Remoortere A, Bushby K, Frants RR, Dunnen JT, van der Maarel SM

Center for Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

Muscular dystrophies comprise a genetically heterogeneous group of degenerative muscle disorders characterized by progressive muscle wasting and weakness. Two forms of limb-girdle muscular dystrophy, 2A and 2B, are caused by mutations in calpain 3 (CAPN3) and dysferlin (DYSF), respectively. While CAPN3 may be involved in sarcomere remodeling, DYSF is proposed to play a role in membrane repair. The coexistence of CAPN3 and AHNAK, a protein involved in subsarcolemmal cytoarchitecture and membrane repair, in the dysferlin protein complex and the presence of proteolytic cleavage fragments of AHNAK in skeletal muscle led us to investigate whether AHNAK can act as substrate for CAPN3. We here demonstrate that AHNAK is cleaved by CAPN3 and show that AHNAK is lost in cells expressing active CAPN3. Conversely, AHNAK accumulates when calpain 3 is defective in skeletal muscle of calpainopathy patients. Moreover, we demonstrate that AHNAK fragments cleaved by CAPN3 have lost their affinity for dysferlin. Thus, our findings suggest interconnectivity between both diseases by revealing a novel physiological role for CAPN3 in regulating the dysferlin protein complex.

Published 2 June 2008 in Hum Mol Genet, 17(12): 1855-66.
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