A model for non-viral gene delivery: through syndecan adhesion molecules and powered by actin.
BACKGROUND
Cell transfection requires cationic DNA complexes and heparan sulfate proteoglycans (HSPGs) at the cell surface. Syndecans are transmembrane HSPGs that are ubiquitously expressed on adherent cells. Their polyanionic heparan sulfate moieties are bound at the distal end of their ectodomain, thus facilitating interaction with large cationic particles.


METHODS
We propose a model for cell entry involving syndecans as receptors for the DNA complexes by comparing transfection with bacteria uptake and using drug inhibition experiments along with confocal microscopy.


RESULTS
When combined with results from the literature, our data suggest the following sequence of events: after initial particle binding, gradual electrostatic zippering of the plasma membrane onto the particle is sustained by lateral diffusion of syndecan molecules that cluster into cholesterol-rich rafts. Clustering in turn triggers PKC activity and linker protein-mediated actin binding to the cytoplasmic tail of the syndecans. Resulting tension fibers and a growing network of cortical actin may then pull the particle into the cell.


CONCLUSIONS
Diversion of integrin- and syndecan-mediated cell adhesion processes for particle engulfment appears to be widely exploited by animals (chylomicrons), by pathogens (bacteria, viruses) and, as suggested here, by non-viral vectors.
Kopatz
Idit
I
Laboratoire de Chimie Génétique associé C.N.R.S./Université Louis Pasteur de Strasbourg, Faculté de Pharmacie, BP 24, 67401 Illkirch, France.
Remy
Jean-Serge
JS
Behr
Jean-Paul
JP
D000199:Actins / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D018613:Microscopy, Confocal; D011509:Proteoglycans / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D055672:Static Electricity; D053667:Syndecans
D000199:Actins; D015815:Cell Adhesion Molecules; D008562:Membrane Glycoproteins; D011509:Proteoglycans; D053667:Syndecans; D002784:Cholesterol