title: Quantitatively distinct requirements for signaling-competent cell spreading on engineered versus natural adhesion ligands.
abstract: To design synthetic microenvironments that elicit desired cell behaviors, we must better understand the molecular mechanisms by which cells interact with candidate biomaterials. Using cell lines with distinct alpha5beta1 integrin expression profiles, we demonstrate that this integrin mediates cell spreading on substrata coated with genetically engineered artificial extracellular matrix (aECM) proteins containing the RGD sequence (RGD-containing aECM protein [aRGD]) but lacking the PHSRN synergy site. Furthermore, aRGD-mediated adhesion stimulates an intracellular focal adhesion kinase (FAK) signal that is indicative of integrin tethering. Although both aRGD and the natural ECM protein fibronectin (FN) support alpha5beta1 integrin-mediated cell spreading, quantitative single-cell analysis revealed that aRGD-mediated spreading requires ten-fold greater threshold amount of integrin expression than FN-mediated spreading. Our analysis demonstrates that aRGD-based substrata mediate both biophysical (cell spreading) and biochemical (FAK signaling) events via the alpha5beta1 integrin, albeit with efficacy quantitatively distinct from that of natural ECM proteins that possess the full spectrum of adhesion and synergy domains.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 210-41, Pasadena, CA 91125, USA.
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: Richman
authors.forename: David A
authors.initials: DA
authors.lastname: Tirrell
authors.forename: Anand R
authors.initials: AR
authors.lastname: Asthagiri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002448:Cell Adhesion; D006224:Cricetinae; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D051416:Focal Adhesion Protein-Tyrosine Kinases; D039081:Integrin alpha5beta1 / Q000502:physiology*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D016326:Extracellular Matrix Proteins; D039081:Integrin alpha5beta1; D009842:Oligopeptides; D011994:Recombinant Proteins; C047981:arginyl-glycyl-aspartic acid; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases