BPAG1 isoform-b: complex distribution pattern in striated and heart muscle and association with plectin and alpha-actinin.
BPAG1-b is the major muscle-specific isoform encoded by the dystonin gene, which expresses various protein isoforms belonging to the plakin protein family with complex, tissue-specific expression profiles. Recent observations in mice with either engineered or spontaneous mutations in the dystonin gene indicate that BPAG1-b serves as a cytolinker important for the establishment and maintenance of the cytoarchitecture and integrity of striated muscle. Here, we studied in detail its distribution in skeletal and cardiac muscles and assessed potential binding partners. BPAG1-b was detectable in vitro and in vivo as a high molecular mass protein in striated and heart muscle cells, co-localizing with the sarcomeric Z-disc protein alpha-actinin-2 and partially with the cytolinker plectin as well as with the intermediate filament protein desmin. Ultrastructurally, like alpha-actinin-2, BPAG1-b was predominantly localized at the Z-discs, adjacent to desmin-containing structures. BPAG1-b was able to form complexes with both plectin and alpha-actinin-2, and its NH(2)-terminus, which contains an actin-binding domain, directly interacted with that of plectin and alpha-actinin. Moreover, the protein level of BPAG1-b was reduced in muscle tissues from plectin-null mutant mice versus wild-type mice. These studies provide new insights into the role of BPAG1-b in the cytoskeletal organization of striated muscle.
Steiner-Champliaud
Marie-France
MF
Clinic of Dermatology, Geneva University Hospital, Rue Micheli-du-Crest 24, 1211 Geneva, Switzerland.
Schneider
Yann
Y
Favre
Bertrand
B
Paulhe
Frédérique
F
Praetzel-Wunder
Silke
S
Faulkner
Georgine
G
Konieczny
Patryk
P
Raith
Marianne
M
Wiche
Gerhard
G
Adebola
Adijat
A
Liem
Ronald K
RK
Langbein
Lutz
L
Sonnenberg
Arnoud
A
Fontao
Lionel
L
Borradori
Luca
L
D000185:Actinin / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002457:Cell Extracts; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D000071821:Dystonin; D006801:Humans; D007106:Immune Sera; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000378:metabolism / Q000648:ultrastructure; D009206:Myocardium / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D051190:Plectin / Q000172:deficiency / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D020449:Repetitive Sequences, Amino Acid
D002352:Carrier Proteins; D002457:Cell Extracts; D003598:Cytoskeletal Proteins; C486268:DST protein, human; C095667:Dst protein, mouse; D000071821:Dystonin; D007106:Immune Sera; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; D051190:Plectin; D020033:Protein Isoforms; D000185:Actinin