Distinct biophysical mechanisms of focal adhesion kinase mechanoactivation by different extracellular matrix proteins.
Matrix mechanics controls cell fate by modulating the bonds between integrins and extracellular matrix (ECM) proteins. However, it remains unclear how fibronectin (FN), type 1 collagen, and their receptor integrin subtypes distinctly control force transmission to regulate focal adhesion kinase (FAK) activity, a crucial molecular signal governing cell adhesion/migration. Here we showed, using a genetically encoded FAK biosensor based on fluorescence resonance energy transfer, that FN-mediated FAK activation is dependent on the mechanical tension, which may expose its otherwise hidden FN synergy site to integrin α5. In sharp contrast, the ligation between the constitutively exposed binding motif of type 1 collagen and its receptor integrin α2 was surprisingly tension-independent to induce sufficient FAK activation. Although integrin α subunit determines mechanosensitivity, the ligation between α subunit and the ECM proteins converges at the integrin β1 activation to induce FAK activation. We further discovered that the interaction of the N-terminal protein 4.1/ezrin/redixin/moesin basic patch with phosphatidylinositol 4,5-biphosphate is crucial during cell adhesion to maintain the FAK activation from the inhibitory effect of nearby protein 4.1/ezrin/redixin/moesin acidic sites. Therefore, different ECM proteins either can transmit or can shield from mechanical forces to regulate cellular functions, with the accessibility of ECM binding motifs by their specific integrin α subunits determining the biophysical mechanisms of FAK activation during mechanotransduction.
Neuroscience Program, Department of Mechanical Science and Engineering, and Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, Urbana, IL 61801.
Jihye
J
Seong
Arash
A
Tajik
Jie
J
Sun
Jun-Lin
JL
Guan
Martin J
MJ
Humphries
Susan E
SE
Craig
Asha
A
Shekaran
Andrés J
AJ
García
Shaoying
S
Lu
Michael Z
MZ
Lin
Ning
N
Wang
Yingxiao
Y
Wang
D001665:Binding Sites / Q000235:genetics; D001696:Biomechanical Phenomena; D045744:Cell Line, Tumor; D024042:Collagen Type I / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015151:Immunoblotting; D047468:Immunoprecipitation; D039421:Integrin alpha2 / Q000235:genetics / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology*
D024042:Collagen Type I; D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D039421:Integrin alpha2; D051416:Focal Adhesion Protein-Tyrosine Kinases
FRET biosensor; intracellular tension; substrate rigidity