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The ZZ Domain of Dystrophin in DMD : Making Sense of Missense Mutations
Author(s) -
Vulin Adeline,
Wein Nicolas,
Strandjord Dana M.,
Johnson Eric K.,
Findlay Andrew R.,
Maiti Baijayanta,
Howard Michael T.,
Kaminoh Yuuki J.,
Taylor Laura E.,
Simmons Tabatha R.,
Ray Will C.,
Montanaro Federica,
Ervasti Jim M.,
Flanigan Kevin M.
Publication year - 2014
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.22479
Subject(s) - dystrophin , dystroglycan , missense mutation , biology , utrophin , zinc finger , transmembrane domain , duchenne muscular dystrophy , mutation , genetics , microbiology and biotechnology , muscular dystrophy , amino acid , gene , laminin , transcription factor , cell
Duchenne muscular dystrophy ( DMD ) is associated with the loss of dystrophin, which plays an important role in myofiber integrity via interactions with β‐dystroglycan and other members of the transmembrane dystrophin‐associated protein complex. The ZZ domain, a cysteine‐rich zinc‐finger domain near the dystrophin C‐terminus, is implicated in forming a stable interaction between dystrophin and β‐dystroglycan, but the mechanism of pathogenesis of ZZ missense mutations has remained unclear because not all such mutations have been shown to alter β‐dystroglycan binding in previous experimental systems. We engineered three ZZ mutations (p.Cys3313Phe, p.Asp3335His, and p.Cys3340Tyr) into a short construct similar to the Dp71 dystrophin isoform for in vitro and in vivo studies and delineated their effect on protein expression, folding properties, and binding partners. Our results demonstrate two distinct pathogenic mechanisms for ZZ missense mutations. The cysteine mutations result in diminished or absent subsarcolemmal expression because of protein instability, likely due to misfolding. In contrast, the aspartic acid mutation disrupts binding with β‐dystroglycan despite an almost normal expression at the membrane, confirming a role for the ZZ domain in β‐dystroglycan binding but surprisingly demonstrating that such binding is not required for subsarcolemmal localization of dystrophin, even in the absence of actin binding domains.