Calpain cleavage within dysferlin exon 40a releases a synaptotagmin-like module for membrane repair.
Bottom Line: Here we show that injury-activated cleavage of dysferlin is mediated by the ubiquitous calpains via a cleavage motif encoded by alternately spliced exon 40a.Of importance, we reveal that myoferlin and otoferlin are also cleaved enzymatically to release similar C-terminal modules, bearing two C2 domains and a transmembrane domain.Evolutionary preservation of this feature highlights its functional importance and suggests that this highly conserved C-terminal region of ferlins represents a functionally specialized vesicle fusion module.
Affiliation: Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Sydney, NSW 2145, Australia Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, Australia.Show MeSH
Related in: MedlinePlus
Mentions: Immunolabeling experiments of differentiated MO3.13 oligodendrocytes (differentiation increases dysferlin expression) subjected to ballistics injury with silica microparticles (4-μm diameter) revealed robust labeling for dysferlin at sites of membrane injury within 10 s of injury (Figure 5, top, left; Hamlet-1, green), concordant with our previous study in cultured human myotubes (Lek et al., 2013). Similarly, injury-induced dysferlin accumulation could be detected only with the C-terminal antibody Hamlet-1 and not the N-terminal antibody Romeo (Figure 5, top, middle; Romeo, red). Staining of primary human myotubes, biasing antibody binding to the dysferlin N-terminus by incubating with the N-terminal Romeo antibody before the C-terminal antibody Hamlet-1, similarly highlights specific recognition of the dysferlin C-terminus but not the dysferlin N-terminus at injury sites (Figure 5, second row).
Affiliation: Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Sydney, NSW 2145, Australia Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, Australia.