PubMed · 1683425
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1991-12-07. Antisensibility: progress and prospects.. https://pubmed.ncbi.nlm.nih.gov/1683425/
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Peptide nucleic acids (PNAs) have shown great promise as potential antisense drugs; however, poor cellular delivery limits their applications. Improved delivery into mammalian cells and enhanced biological activity of PNAs have been achieved by coupling to cell-penetrating peptides (CPPs). Structural requirements for the shuttling ability of these peptides as well as structural properties of the conjugates such as the linker type and peptide position remained controversial, so far. In the present study an 18mer PNA targeted to the cryptic splice site of a mutated beta-globin intron 2, which had been inserted into a luciferase reporter gene coding sequence, was coupled to various peptides. As the peptide lead we used the cell-penetrating alpha-helical amphipathic peptide KLAL KLAL KAL KAAL KLA-NH2 [model amphipathic peptide (MAP)] which was varied with respect to charge and structure-forming properties. Furthermore, the linkage and the localization of the attached peptide (C- vs N-terminal) were modified. Positive charge as well as helicity and amphipathicity of the KLA peptide was all required for efficient dose-dependent correction of aberrant splicing. The highest antisense effect was reached within 4 h without any transfection agent. Stably linked conjugates were also efficient in correction of aberrant splicing, suggesting that a cleavable disulfide bond between CPP and PNA is clearly not essential. Moreover, the placement of the attached peptide turned out to be crucial for attaining antisense activity. Coadministration of endosome disrupting agents such as chloroquine or Ca2+ significantly increased the splicing correction efficiency of some conjugates, indicating the predominant portion to be sequestered in vesicular compartments.
Klebsiella pneumoniae causes common and severe hospital- and community-acquired infections with a high incidence of multidrug resistance. The emergence and spread of beta-lactamase-producing K. pneumoniae strains highlight the need to develop new therapeutic strategies. In this study, we developed antisense peptide nucleic acids (PNAs) conjugated to the (KFF)(3)K peptide and investigated whether they could mediate gene-specific antisense effects in K. pneumoniae. No outer membrane permeabilization was observed with antisense PNAs when used alone. Antisense peptide-PNAs targeted at two essential genes, gyrA and ompA, were found to be growth inhibitory at concentrations of 20 muM and 40 muM, respectively. Mismatched antisense peptide-PNAs with sequence variations of the gyrA and ompA genes when used as controls were not growth inhibitory. Bactericidal effects exerted by peptide-anti-gyrA PNA and peptide-anti-ompA PNA on cells were observed within 6 h of treatment. The antisense peptide-PNAs specifically inhibited expression of DNA gyrase subunit A and OmpA from the respective targeted genes in a dose-dependent manner. Both antisense peptide-PNAs cured IMR90 cell cultures that were infected with K. pneumoniae (10(4) CFU) in a dose-dependent manner without any noticeable toxicity to the human cells.
Wnt signaling induces the nuclear accumulation of beta-catenin and transcription of specific target genes via the DNA-binding proteins TCF/Lef. Although all known beta-catenin target genes encode proteins, genome-wide RNA profiling studies indicate that many transcripts do not have this capability. Transcription factor-binding sites associated with these noncoding transcripts can be identified using unbiased techniques such as serial analysis of chromatin occupancy (SACO). We used this method to identify a beta-catenin-regulated antisense RNA expressed in HCT116 colorectal carcinoma cells, a cellular model of activated beta-catenin signaling. Genomic signature tags designating putative beta-catenin-binding sites mapped to the 3'-untranslated region (3'-UTR) of the E2F4 gene. We showed that both beta-catenin and TCF4 bind to the E2F4 3'-UTR site in vivo, inducing expression of an E2F4 antisense transcript. LiCl, which mimics Wnt signaling, also induced expression of the E2F4 antisense transcript and decreased E2F4 protein levels. This effect was blocked by a cDNA expressing the E2F4 3'-UTR sense strand. The antisense-mediated decrease in E2F4 protein was reflected by reduced E2F4 association with specific target genes, including CCNA2, CDC2, PCNA, and Rad54. We propose that Wnt/beta-catenin signaling may contribute to colorectal carcinogenesis by reducing the level of the E2F4 cell cycle repressor via an antisense mechanism.