title: Protein kinase A inhibition modulates the intracellular routing of gene delivery vehicles in HeLa cells, leading to productive transfection.
abstract: Cellular entry of nanoparticles for drug- and gene delivery relies on various endocytic pathways, including clathrin- and caveolae-mediated endocytosis. To improve delivery, i.e., the therapeutic and/or cell biological impact, current efforts are aimed at avoiding processing of the carriers along the degradative clathrin-mediated pathway towards lysosomes, and promoting that along the caveolae-mediated pathway. Here, we demonstrate the effective internalization of branched polyethylenimine polymers (BPEI), complexed with nucleic acids, by HeLa cells along both pathways. However, transfection efficiency or nuclear ODN delivery primarily occurs via the caveolae-mediated pathway, along which delivery into lysosomes is avoided. Interestingly, inhibition of intracellular protein kinase A (PKA) activity modulates the intracellular trafficking of both poly- and lipoplexes along the clathrin-mediated pathway by impeding trafficking into the late endosomal/lysosomal compartments, thus avoiding degradation. In case of BPEI polyplexes this promotes their transfection efficiency by 2-3 fold. Evidence excludes early endosomes as a major site for BPEI-mediated release/delivery. Rather, we identify a novel compartment, tentatively characterized as a transferrin(-)/rab9(-)/LAMP1(-) compartment, to which cargo within the clathrin-mediated pathway of endocytosis is rerouted upon inhibition of PKA, and which may act as an alternative and effective site of cargo release in gene delivery. Our findings offer new opportunities for improving gene delivery by non-viral based nanoparticles.
authors.affiliation: University Medical Center Groningen, University of Groningen, Department of Cell Biology/Membrane Cell Biology, A. Deusinglaan 1, Groningen, The Netherlands.
authors.forename: Zia
authors.initials: Z
authors.lastname: ur Rehman
authors.forename: Dick
authors.initials: D
authors.lastname: Hoekstra
authors.forename: Inge S
authors.initials: IS
authors.lastname: Zuhorn
mesh_terms: D002966:Clathrin / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D004337:Drug Carriers / Q000737:chemistry*; D004705:Endocytosis; D011992:Endosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D018014:Gene Transfer Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry*; D009841:Oligonucleotides / Q000235:genetics*; D011094:Polyethyleneimine / Q000737:chemistry*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D014162:Transfection
chemical_list: D002966:Clathrin; D004337:Drug Carriers; D008055:Lipids; C086724:Lipofectamine; D009841:Oligonucleotides; D047428:Protein Kinase Inhibitors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D011094:Polyethyleneimine; D017868:Cyclic AMP-Dependent Protein Kinases