Small-Molecule-Modified Surfaces Engage Cells through the α_vβ₃ Integrin

Abstract

Integrins play myriad and vital roles in development and disease. They connect a cell with its surroundings and transmit chemical and mechanical signals across the plasma membrane to the cell’s interior. Dissecting their roles in cell behavior is complicated by their overlapping ligand specificity and shared downstream signaling components. In principle, synthetic peptides can be used to modify surfaces to mimic extracellular matrix proteins by supporting integrin-mediated adhesion, but most short peptide sequences lack selectivity for one integrin over others. In contrast, synthetic integrin antagonists can be highly selective. We hypothesized that this selectivity could be exploited if antagonists, when immobilized, could support cellular adhesion and activate signaling by engaging specific cell-surface integrins. To investigate this possibility, we designed a bifunctional (RGD)-based peptidomimetic for surface presentation. Our conjugate combines a high affinity integrin ligand with a biotin moiety; the former engages the αvβ3 integrin and the latter allows for presentation on streptavidin-coated surfaces. Surfaces decorated with this ligand promote both cellular adhesion and integrin activation. Moreover, the selectivity of these surfaces for the αvβ3 integrin can be exploited to capture a subset of cells from a mixed population. We anticipate that surfaces displaying highly selective small molecule ligands can reveal the contributions of specific integrin heterodimers to cell adhesion and signaling.

A cell adhesive peptide from tropoelastin promotes sequential cell attachment and spreading via distinct receptors

“…This was supported by the lack of cation dependence in the cell attachment process. The AG73 peptide promotes only cell attachment, whereas the EF1 peptide promotes both cell attachment and spreading, supporting the notion that syndecans are responsible for the cell attachment process, while integrins are vital for cell spreading [36,64]. In this study, the inclusion of both P1F6 and VNR1 antibodies inhibited cell spreading on Peptide 302-322, confirming the involvement of both a v b 3 and a v b 5 integrins in this process.…”

“…Furthermore, two active peptides derived from the mouse laminin a1 chain, AG73 which binds to syndecan, and EF1 which interacts with a 2 b 1 integrin, demonstrate different levels of cell binding and spreading. The AG73 peptide promotes only cell attachment, whereas the EF1 peptide promotes both cell attachment and spreading, supporting the notion that syndecans are responsible for the cell attachment process, while integrins are vital for cell spreading [36,64]. Similarly, the ADAM12 metallopeptidase sequence contains a cysteine-rich domain that initially binds mesenchymal cell syndecans, which in turn promote cell spreading through integrin b 1 [65].…”

Integrin-Generated Forces Lead to Streptavidin-Biotin Unbinding in Cellular Adhesions

“…Overall, our results are significant because the streptavidin-biotin association is widely used to display small molecules and peptides to screen for cues that trigger cell signaling pathways (51). Therefore, these results suggest that more robust immobilization strategies are needed to exclude the possibility of cell-based dissociation of surface ligands and remodeling of the surface, which may obscure results.…”

Signals from the surface modulate differentiation of human pluripotent stem cells through glycosaminoglycans and integrins

“…We anticipate that altering the substrate during different stages could also improve differentiation outcomes. Because streptavidincoated surfaces are compatible with typical multiwell-format plastic culture plates, this surface fabrication strategy can be used to immobilize new types of peptides (48) or other small molecules (24) to probe the cross-talk between soluble and insoluble signaling in diverse cell types and cells at different stages of differentiation.…”

“…First, surfaces can be tailored to present ligands that promote adhesion of specific cell populations during differentiation (24). Second, surfaces can be devised to specifically activate (or mitigate) signal transduction pathways.…”