title: Mg2+ modulates integrin-extracellular matrix interaction in vascular smooth muscle cells studied by atomic force microscopy.
abstract: Atomic force microscopy (AFM) was used to investigate the interaction between alpha5beta1 integrin and fibronectin (FN) in the presence of divalent cations. AFM probes were labeled with FN and used to measure binding strength between alpha5beta1 integrin and FN by quantifying the force required to break single FN-integrin bonds on a physiological range of loading rates (100-10,000 pN/s). The force necessary to rupture single alpha5beta1-FN bond increased twofold over the regime of loading rates investigated. Changes in Mg(2+) and Ca(2+) concentration affected the thermodynamical parameters of the interaction and modulated the binding energy. These data indicate that the external ionic environment in which vascular smooth muscle cells reside, influences the mechanical parameters that define the interaction between the extracellular matrix and integrins. Thus, in a dynamic mechanical environment such as the vascular wall, thermodynamic binding properties between FN and alpha5beta1 integrin vary in relation to locally applied loads and divalent cations concentrations. These changes can be recorded as direct measurements on live smooth muscle cells by using AFM.
authors.affiliation: Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA. trache@tamu.edu
authors.forename: Andreea
authors.initials: A
authors.lastname: Trache
authors.forename: Jerome P
authors.initials: JP
authors.lastname: Trzeciakowski
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Meininger
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D018625:Microscopy, Atomic Force / Q000379:methods; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D013816:Thermodynamics
chemical_list: D005353:Fibronectins; D039081:Integrin alpha5beta1; D008274:Magnesium