AHNAK, a novel component of the dysferlin protein complex, redistributes to the cytoplasm with dysferlin during skeletal muscle regeneration.
Mutations in dysferlin cause limb girdle muscular dystrophy 2B, Miyoshi myopathy and distal anterior compartment myopathy. Dysferlin is proposed to play a role in muscle membrane repair. To gain functional insight into the molecular mechanisms of dysferlin, we have searched for dysferlin-interacting proteins in skeletal muscle. By coimmunoprecipitation coupled with mass spectrometry, we demonstrate that AHNAK interacts with dysferlin. We defined the binding sites in dysferlin and AHNAK as the C2A domain in dysferlin and the carboxyterminal domain of AHNAK by glutathione S-transferase (GST)-pull down assays. As expected, the N-terminal domain of myoferlin also interacts with the carboxyterminal domain of AHNAK. In normal skeletal muscle, dysferlin and AHNAK colocalize at the sarcolemmal membrane and T-tubules. In dysferlinopathies, reduction or absence of dysferlin correlates with a secondary muscle-specific loss of AHNAK. Moreover, in regenerating rat muscle, dysferlin and AHNAK showed a marked increase and cytoplasmic localization, consistent with the direct interaction between them. Our data suggest that dysferlin participates in the recruitment and stabilization of AHNAK to the sarcolemma and that AHNAK plays a role in dysferlin membrane repair process. It may also have significant implications for understanding the biology of AHNAK-containing exocytotic vesicles, "enlargosomes," in plasma membrane remodeling and repair.
Huang
Yanchao
Y
Center for Human and Clinical Genetics, Leiden Univesity Medical Center, Leiden, The Netherlands.
Laval
Steven H
SH
van Remoortere
Alexandra
A
Baudier
Jacques
J
Benaud
Chriselle
C
Anderson
Louise V B
LV
Straub
Volker
V
Deelder
Andre
A
Frants
Rune R
RR
den Dunnen
Johan T
JT
Bushby
Kate
K
van der Maarel
Silvère M
SM
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D000073939:Dysferlin; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D009154:Mutation; D009363:Neoplasm Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000502:physiology*
C075176:AHNAK protein, human; C489572:Ahnak protein, mouse; D002352:Carrier Proteins; C114839:DYSF protein, human; C497505:Dysf protein, mouse; D000073939:Dysferlin; D008565:Membrane Proteins; D009124:Muscle Proteins; D009363:Neoplasm Proteins