The signal peptide NPFSD fused to ricin A chain enhances cell uptake and cytotoxicity in Candida albicans

TAQing2.0 for genome reorganization of asexual industrial yeasts by direct protein transfection

Genomic rearrangements often generate phenotypic diversification. We previously reported the TAQing system where genomic rearrangements are induced via conditional activation of a restriction endonuclease in yeast and plant cells to produce mutants with marked phenotypic changes. Here we developed the TAQing2.0 system based on the direct delivery of endonucleases into the cell nucleus by cell-penetrating peptides. Using the optimized procedure, we introduce a heat-reactivatable endonuclease TaqI into an asexual industrial yeast (torula yeast), followed by a transient heat activation of TaqI. TAQing2.0 leads to generation of mutants with altered flocculation and morphological phenotypes, which exhibit changes in chromosomal size. Genome resequencing suggested that torula yeast is triploid with six chromosomes and the mutants have multiple rearrangements including translocations having the TaqI recognition sequence at the break points. Thus, TAQing2.0 is expected as a useful method to obtain various mutants with altered phenotypes without introducing foreign DNA into asexual industrial microorganisms.

The TAQing system is upgraded and optimised as the foreign-DNA-free genome engineering technology, TAQing2.0. Genomic rearrangements are randomly induced by introducing the TaqI restriction endonuclease into non-sporulating industrial yeast with cell-penetrating peptides, leading to generation of mutants with altered phenotypes.

Cellular uptake mechanisms and potential therapeutic utility of peptidic cell delivery vectors: progress 2001-2006

Cell delivery vectors (CDVs) are short amphipathic and cationic peptides and peptide derivatives, usually containing multiple lysine and arginine residues. They possess inherent membrane activity and can be conjugated or complexed with large impermeable macromolecules and even microscopic particles to facilitate cell entry. Various mechanisms have been proposed but it is now becoming clear that the main port of entry into cells of such CDV constructs involves adsorptive-mediated endocytosis rather than direct penetration of the plasma membrane. It is still unclear, however, how and to what extent CDV constructs are capable of exiting endosomal compartments and reaching their intended cellular site of action, usually the cytosol or the nucleus. Furthermore, although many CDVs can mediate cellular uptake of their cargo and appear comparatively non-toxic to cells in tissue culture, the utility of CDVs for in vivo applications remains poorly understood. Whatever the mechanisms of cell entry and disposition, the overriding question as far as potential pharmacological application of CDV conjugates is concerned is whether or not a therapeutic margin can be achieved by their administration. Such a margin will only result if the intracellular concentration in the target tissues necessary to elicit the biological effect of the CDV cargo can be achieved at systemic CDV exposure levels that are non-toxic to both target and bystander cells. It is proposed that the focus of CDV research now be shifted from mechanistic in vitro studies with labeled but otherwise unconjugated CDVs to in vivo pharmacological and toxicological studies using CDV-derivatized and other cationized forms of inherently non-permeable macromolecules of true therapeutic interest.

In vitro panning of a targeting peptide to hepatocarcinoma from a phage display peptide library

Phage display technology has been used as a powerful tool in the discovery of ligands specific to receptor(s) on the surface of a cancer cell and could also impact clinical issues including functional diagnosis and cell-specific drug delivery. After three rounds of in vitro panning and two rounds of reverse absorption, a group of phages capable of addressing BEL-7402 enormously were obtained for further analysis. Through a cell-based ELISA, immunofluorescence, FACS, and in vivo binding study, WP05 (sequence TACHQHVRMVRP) was demonstrated to be the most effective peptide in targeting four kinds of liver cancer cell lines (BEL-7402, BEL-7404, SMMC-7721, and HepG2), but not the normal liver cell line HL-7702. In conclusion, the peptide WP05 which was screened by in vitro phage display technology was proved to be a targeting peptide to several common hepatocellular carcinoma cell lines.

Free uptake of cell-penetrating peptides by fission yeast

An increasing number of peptides translocate the plasma membrane of mammalian cells promising new avenues for drug delivery. However, only a few examples are known to penetrate the fungal cell wall. We compared the capacity of different fluorophore-labelled peptides to translocate into fission yeast and human cells and determined their intracellular distribution. Most of the 20 peptides tested were able to enter human cells, but only one, transportan 10 (TP10), efficiently penetrated fission yeast and was distributed uniformly inside the cells. The results show that the fungal cell wall may reduce, but does not block peptide uptake.