Calpain cleavage within dysferlin exon 40a releases a synaptotagmin-like module for membrane repair

Dysferlin and calpain are important mediators of the emergency response to repair plasma membrane injury. Our previous research revealed that membrane injury induces cleavage of dysferlin to release a synaptotagmin-like C-terminal module we termed mini-dysferlinC72. Here we show that injury-activate...

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Published in:	Molecular biology of the cell Vol. 25; no. 19; pp. 3037 - 3048
Main Authors:	Redpath, G M I, Woolger, N, Piper, A K, Lemckert, F A, Lek, A, Greer, P A, North, K N, Cooper, S T
Format:	Journal Article
Language:	English
Published:	United States The American Society for Cell Biology 01-10-2014
Subjects:	Amino Acid Sequence Animals Calcium-Binding Proteins - metabolism Calpain - genetics Calpain - metabolism Carrier Proteins Cell Membrane - metabolism Cells, Cultured Dysferlin HEK293 Cells Human Umbilical Vein Endothelial Cells Humans Membrane Fusion - physiology Membrane Proteins - genetics Membrane Proteins - metabolism Mice Mice, Inbred C57BL Molecular Sequence Data Muscle Proteins - genetics Muscle Proteins - metabolism Protein Isoforms Protein Structure, Tertiary Sequence Alignment Synaptotagmins - metabolism
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Summary:	Dysferlin and calpain are important mediators of the emergency response to repair plasma membrane injury. Our previous research revealed that membrane injury induces cleavage of dysferlin to release a synaptotagmin-like C-terminal module we termed mini-dysferlinC72. 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. An exon 40a-specific antibody recognizing cleaved mini-dysferlinC72 intensely labels the circumference of injury sites, supporting a key role for dysferlinExon40a isoforms in membrane repair and consistent with our evidence suggesting that the calpain-cleaved C-terminal module is the form specifically recruited to injury sites. Calpain cleavage of dysferlin is a ubiquitous response to membrane injury in multiple cell lineages and occurs independently of the membrane repair protein MG53. Our study links calpain and dysferlin in the calcium-activated vesicle fusion of membrane repair, placing calpains as upstream mediators of a membrane repair cascade that elicits cleaved dysferlin as an effector. 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.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1059-1524 1939-4586
DOI:	10.1091/mbc.e14-04-0947