The extracellular domain of integrin α7 is ADP-ribosylated by an arginine-specific ecto-ADP-ribosyltransferase after adding exogenous NAD+ to intact C2C12 skeletal muscle cells. The effect of ADP-ribosylation on the structure or function of integrin α7β1 has not been explored. In the present study, we show that ADP-ribosylation of integrin α7 takes place exclusively in differentiated myotubes and that this post-translational modification modulates the affinity of α7β1 dimer for its ligand, laminin. ADP-ribosylation in the 37-kDa ‘stalk’ region of α7 that takes place at micromolar NAD+ concentrations increases the binding of the α7β1 dimer to laminin. Increased in vitro binding of integrin α7β1 to laminin after ADP-ribosylation of the 37-kDa fragment of α7 requires the presence of Mn2+ and it is not observed in the presence of Mg2+. In contrast, ADP-ribosylation of the 63-kDa N-terminal region comprising the ligand-binding site of α7 that occurs at approx. 100 μM NAD+ inhibits the binding of integrin α7β1 to laminin. Furthermore, incubation of C2C12 myotubes with NAD+ increases the expression of an epitope on integrin β1 subunit recognized by monoclonal antibody 9EG7. We discuss our results based on the current models of integrin activation. We also hypothesize that ADP-ribosylation may represent a mechanism of regulation of integrin α7β1 function in myofibres in vivo when the continuity of the membrane is compromised and NAD+ is available as a substrate for ecto-ADP-ribosylation.
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Research Article|
December 14 2004
ADP-ribosylation of integrin α7 modulates the binding of integrin α7β1 to laminin
Zhefeng ZHAO;
Zhefeng ZHAO
1Department of Biochemistry, Kansas State University, 104 Willard Hall, Manhattan, KS 66506, U.S.A.
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Joanna GRUSZCZYNSKA-BIEGALA;
Joanna GRUSZCZYNSKA-BIEGALA
1Department of Biochemistry, Kansas State University, 104 Willard Hall, Manhattan, KS 66506, U.S.A.
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Anna ZOLKIEWSKA
Anna ZOLKIEWSKA
1
1Department of Biochemistry, Kansas State University, 104 Willard Hall, Manhattan, KS 66506, U.S.A.
1To whom correspondence should be addressed (email zolkiea@ksu.edu).
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Publisher: Portland Press Ltd
Received:
April 08 2004
Revision Received:
August 17 2004
Accepted:
September 13 2004
Accepted Manuscript online:
September 13 2004
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2005
Biochem J (2005) 385 (1): 309–317.
Article history
Received:
April 08 2004
Revision Received:
August 17 2004
Accepted:
September 13 2004
Accepted Manuscript online:
September 13 2004
Citation
Zhefeng ZHAO, Joanna GRUSZCZYNSKA-BIEGALA, Anna ZOLKIEWSKA; ADP-ribosylation of integrin α7 modulates the binding of integrin α7β1 to laminin. Biochem J 1 January 2005; 385 (1): 309–317. doi: https://doi.org/10.1042/BJ20040590
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