.
Angewandte
Communications
DOI: 10.1002/anie.201206370
Selective Cell Adhesion
Functionalizing avb3- or a5b1-Selective Integrin Antagonists for
Surface Coating: A Method To Discriminate Integrin Subtypes
In Vitro**
Florian Rechenmacher, Stefanie Neubauer, Julien Polleux, Carlos Mas-Moruno,
Mariarosaria De Simone, Elisabetta Ada Cavalcanti-Adam, Joachim P. Spatz, Reinhard Fꢀssler,
and Horst Kessler*
Investigating the different functions of distinct surface
receptors is essential to understand the complex interactions
between cells and their extracellular environment. Cells use
specific transmembrane receptors of the integrin family to
anchor and respond to extracellular matrix (ECM) proteins.
In doing so, integrins are capable of regulating cell migration,
survival, cell cycle progression, and differentiation, which are
essential tasks for the development of all multicellular
organisms. Integrins are often classified according to their
binding specificity for extracellular ligands. For instance,
arginine–glycine–aspartate (RGD)-containing proteins,[1]
such as fibronectin (Fn), exhibit high binding affinity to 8 of
the 24 integrins expressed in mammals. Among the fibronec-
tin-binding integrins, avb3 and a5b1 play crucial roles during
embryogenesis, angiogenesis, and in pathology.[2–4] Despite
the wealth of information on integrin biology, it is unclear
how cell functions and responses are regulated by a single
integrin subtype. To address this relevant issue, the design of
new active molecules that are able to selectively recognize
distinct integrin subtypes is essential for in vitro studies and
the development of selective drugs for disease therapy
(personalized medicine). Moreover, the conjugation of func-
tional groups to such ligands without affecting their affinity
and selectivity for cell surface receptors remains a difficult
task to achieve.
adhesion of either avb3- or a5b1-expressing cells was clearly
mediated or blocked through coating of gold nanoarrays with
these molecules, thus giving striking evidence for their
selectivity. These compounds are a powerful tool to elucidate
the difference between avb3 and a5b1 integrin-mediated cell
adhesion.
The interaction of integrins with ECM proteins leads to
the clustering of integrins and the recruitment of intracellular
proteins to the integrin cytoplasmic domains.[6] The recruited
proteins, collectively called the adhesome,[7] play crucial roles
in transducing integrin-mediated processes and are thus also
involved in biological processes, such as angiogenesis and
tumor development. They are therefore interesting targets for
pharmacological research.[8,9] Although the functions of
integrins in cell adhesion and formation of focal contacts
have been studied with unselective cyclic RGD peptides and
other ECM mimetics,[10] the exact role of avb3 and a5b1
integrin subtypes played in these processes remains to be
elucidated. Natural integrin ligands are not well suited for
those studies owing to the lack of integrin subtype selectiv-
ity.[11]
Coating of surfaces with peptidic integrin ligands for
biophysical cell adhesion studies, to develop implant materi-
als, or to identify binding motifs was realized in various
cases.[10,12] However, it turned out that peptides, in contrast to
peptidomimetics, were not able to achieve high activity and
sufficient selectivity. Nowadays, it is still challenging to
functionalize selective peptidomimetics for this purpose
without losing activity.
Herein, we report a strategy to synthesize avb3- or a5b1-
specific ligands for the functionalization of nanostructured
gold surfaces[5] and demonstrate that cell adhesion can be
selectively mediated by a single integrin subtype. The
[*] F. Rechenmacher,[+] S. Neubauer,[+] Dr. C. Mas-Moruno,
Dr. M. De Simone
Dr. E. A. Cavalcanti-Adam, Prof. J. P. Spatz
Max Planck-Institute for Intelligent Systems, Department of New
Materials and Biosystems, Stuttgart (Germany)
and
Institute for Advanced Study at the Department of Chemistry,
Technische Universitꢀt Mꢁnchen (Germany)
University of Heidelberg, Institute for Physical Chemistry, Depart-
ment of Biophysical Chemistry
Heidelberg (Germany)
Prof. Dr. H. Kessler
Institute for Advanced Study at the Department of Chemistry
Technische Universitꢀt Mꢁnchen
Lichtenbergstrasse 4, 85748 Garching (Germany)
and
Chemistry Department, Faculty of Science
King Abdulaziz University
P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
E-mail: Kessler@tum.de
[+] These authors contributed equally to this work.
[**] We thank the IGSSE (International Graduate School of Science and
Engineering), the Bund der Freunde der TU Mꢁnchen e.V., CompInt
(Materials Science of Complex Interfaces) of the Elite Network of
Bavaria for funding, IAS (Institute for Advanced Study) of Techni-
sche Universitꢀt Mꢁnchen, CIPSM (Center for Integrated Protein
Science Munich), and the Max Planck Society for financial support.
Dr. J. Polleux, Prof. R. Fꢀssler
Max Planck Institut fꢁr Biochemie
Department of Molecular Medicine, Martinsried (Germany)
Supporting information for this article is available on the WWW
1572
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2013, 52, 1572 –1575