Integrin α7β1 is a redox-regulated target of hydrogen peroxide in vascular smooth muscle cell adhesion.
Upon adhesion to laminin-111, aortic smooth muscle cells initially form membrane protrusions with an average diameter of 2.9μm. We identified these protrusions also as subcellular areas of increased redox potential and protein oxidation by detecting cysteine sulfenic acid groups with dimedone. Hence, we termed these areas oxidative hot spots. They are spatially and temporally transient during an early stage of adhesion and depend on the activity of the H(2)O(2)-generating NADPH oxidase 4. Presumably located on cellular protrusions, integrin α7β1 mediates adhesion and migration of vascular smooth muscle cells to laminins of their surrounding basement membrane. Using protein chemistry and mass spectrometry, two specific oxidation sites within the integrin α7 subunit were identified: one located in its genu region and another within its calf 2 domain. Upon H(2)O(2) treatment, two cysteine residues are oxidized thereby unlocking a disulfide bridge. The genu region is a hinge, around which the integrin domains pivot between a bent/inactive and an upright/active conformation. Also, cysteine oxidation within the calf 2 domain permits conformational changes related to integrin activation. H(2)O(2) treatment of α7β1 integrin in concentrations of up to 100μM increases integrin binding activity to laminin-111, suggesting a physiological redox regulation of α7β1 integrin.
Excellence Cluster Cardio-Pulmonary System, Vascular Matrix Biology, Center for Molecular Medicine, Frankfurt University Hospital, Frankfurt am Main, Germany.
Flávia Figueiredo
FF
de Rezende
Augusto
A
Martins Lima
Stephan
S
Niland
Ilka
I
Wittig
Heinrich
H
Heide
Katrin
K
Schröder
Johannes A
JA
Eble
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001011:Aorta / Q000166:cytology; D002448:Cell Adhesion; D002465:Cell Movement; D022081:Cell Surface Extensions; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000378:metabolism*; D039001:Integrin alpha Chains / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism*; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D011485:Protein Binding; D034622:RNA Interference; D051381:Rats
D015703:Antigens, CD; D039001:Integrin alpha Chains; D019012:Integrin beta1; C085725:integrin alpha7; D006861:Hydrogen Peroxide; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat