Small deletions disturb desmin architecture leading to breakdown of muscle cells and development of skeletal or cardioskeletal myopathy.
Desmin ( DES) mutations have been recognized as a cause of desmin-related myopathy (OMIM 601419), or desminopathy, a disease characterized by progressive limb muscle weakness and accumulation of desmin-reactive granular aggregates in the myofibers. We have studied three families with skeletal or cardioskeletal myopathy caused by small in-frame deletions in the desmin gene. The newly identified in-frame deletions E359_S361del and N366del alter the heptad periodicity within a critical 2B coiled-coil segment. Structural analysis reveals that the E359_S361 deletion introduces a second stutter immediately downstream of the naturally occurring stutter, thus doubling the extent of the local coiled-coil unwinding. The N366del mutation converts the wild-type stutter into a different type of discontinuity, a stammer. A stammer, as opposed to a stutter, is expected to cause an extra overwinding of the coiled-coil. These mutations alter the coiled-coil geometry in specific ways leading to fatal damage to desmin filament assembly. Expression studies in two cell lines confirm the inability of desmin molecules with this changed architecture to polymerize into a functional filamentous network. This study provides insights into molecular pathogenetic mechanisms of desmin mutation-associated skeletal and cardioskeletal myopathy.
Kaminska
Anna
A
Neuromuscular Unit, Medical Research Center, Polish Academy of Sciences, Warsaw, Poland.
Strelkov
Sergei V
SV
Goudeau
Bertrand
B
Olivé
Montse
M
Dagvadorj
Ayush
A
Fidzianska
Anna
A
Simon-Casteras
Monique
M
Shatunov
Alexey
A
Dalakas
Marinos C
MC
Ferrer
Isidro
I
Kwiecinski
Hubert
H
Vicart
Patrick
P
Goldfarb
Lev G
LG
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D009202:Cardiomyopathies / Q000235:genetics*; D006224:Cricetinae; D003893:Desmin / Q000737:chemistry / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000473:pathology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000473:pathology* / Q000648:ultrastructure; D009140:Musculoskeletal Diseases / Q000235:genetics*; D009206:Myocardium / Q000473:pathology; D010375:Pedigree; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D003893:Desmin