Cationic Cytosine Morpholino‐Based Transporters: Synthesis and Regulation of Intracellular Localization

Abstract

Cationic guanidinium and phosphonium functionalized cytosine morpholino tetramer (G3) and trimer (P3) have been reported for the first time. They show efficient cellular uptake properties in full growth medium, quantified by fluorescence activated cell sorting (FACS) and visualized by fluorescence microscopy. An interesting feature of these transporters is their localization in the nucleolus or the rest of nucleus, determined by the nature of cationic moieties attached with cytosine base. Co-staining with MitoTracker Deep Red depicts their ability to penetrate mitochondrial membrane. Fluorescence imaging displays their uniform distribution throughout zebrafish larvae with no significant toxicity. FACS analysis at 4 8 C indicated that transfection of G3 transporter is energy dependent whereas P3 is energy independent. When covalently conjugated, G3 is capable of transporting a 25-mer phosphorodiamidate morpholino oligomer (PMO) into the cells. It exhibits antisense effect against Gli1 gene in hedgehog pathway, confirmed in preliminary b-glactosidase assay performed in Ptch1 -/cells. Further antisense effect was confirmed when G3-conjugated zebrafish Gli1-PMO was injected into embryo to obtain Gli1dependent phenotypes. To the best of our knowledge, herein, we first report that molecular transporters with a minimum number of three cationic groups are capable of efficiently passing through plasma, nuclear and mitochondrial membranes and show distribution in zebrafish larvae.[a] Dr. Figure 1. Chemical structures of (a) DNA, (b) PMO, transporters (c) G3 (1) and (d) P3 (2).

C5-pyrimidine-functionalized morpholino oligonucleotides exhibit differential binding affinity, target specificity and lipophilicity

“…As standardized by Nandi et al 31,32 in the case of the morpholino cytidine 2, the functionalizations were done by Pd-catalyzed cross-coupling reactions (Suzuki, Sonogashira and Heck coupling) to obtain products 3a-j. For the synthesis of the m5C morpholino (5-methyl morpholino cytosine) subunit, we started from compound 2a.…”

“…29 In this direction, we initially disclosed the synthesis of 5-alkynylated uracil-morpholino monomers, 5-substituted morpholino cytidine nucleosides including 8-substituted morpholino purine nucleosides using Pd-catalyzed cross-coupling reactions. [30][31][32][33] However, in these reports, none of the nucleosides were converted to chlorophosphoramidates that were suitable for PMO synthesis. Hence, as part of our research towards the development of functionalized PMOs ( F-PMOs), we report herein the synthesis of functionalized morpholino chlorophosphoramidates of cytidine, uridine (Fig.…”

Internal Oligoguanidinium Transporter: Mercury-Free Scalable Synthesis, Improvement of Cellular Localization, Endosomal Escape, Mitochondrial Localization, and Conjugation with Antisense Morpholino for NANOG Inhibition to Induce Chemosensitization of Taxol in MCF-7 Cells

“…The NANOG ASO IGT-PMO conjugates ( 15a ) and its control scrambled-IGT-PMO ( 15b ) were synthesized from commercially available PMO by click reaction ,, (Scheme and Scheme S3). All the conjugated PMOs were passed through a 3000 MW cutoff filter unit (Amicon Ultra) and then concentrated and precipitated with excess of chilled acetone.…”

“…As a part of our research toward the development of cell-penetrating PMO, − we reported earlier internal guanidinium-based cellular transporters IGTs 1 and 2 (Figure ) with the incorporation of guanidinium linkages between heterocyclic six-membered rings such as aminopiperidine, piperazine, and 6-aminomorpholine and demonstrate the PMO delivery in Shh-LIGHT2 cells and the zebrafish model . To the best of our knowledge, except for Girlat’s bicyclic guanidinium oligomers, no cell-penetration data is available for nonpeptidic and disubstituted internal guanidinium transporters.…”

Synthesis of 5′-Thiol Functionalized Morpholino Oligo-Nucleotide and Subsequent Conjugation with IGT to Improve Delivery and Antisense Efficacy In Vitro

“…An internal oligo-guanidinium transporter containing hexafluoro-isopropyl group (HF-IGT) was chosen for this, as its activity on conjugation with Nanog PMO at 3′ is already known . Even though cationic PMOs − have the advantage of at-a-stretch synthesis, a separate conjugation scheme avoids the usage of modified monomers and allows standard synthesis protocols of amidates − as well as the full length PMO. , …”