Efficient delivery of heterologous molecules for treatment of cells is a great challenge in modern medicine and pharmacology. Cell penetrating peptides (CPPs) may improve efficient delivery of a wide range of macromolecular cargos including plasmid DNA, small interfering RNA, drugs, nanoparticulate pharmaceutical carriers and anticancer drugs. In this paper, we present history of CPPs' discovery with a special attention drawn to sequences of viral origin. We also describe different CPP families with regard to their physicochemical properties and numerous mechanisms of CPP cell uptake by direct penetration and endocytotic pathways. A detailed description is focused on formation of carrier-cargo complexes, which are needed for practical use of CPP in medicine and biotechnology. Examples of successful application of CPPs in treatment of human diseases are also presented, including decreased tumor growth and induction of cancer cell death. Finally, we review modern design approaches to novel CPPs and prediction of their activity. To sum up, the current review presents a thorough and up-to-date knowledge about CPPs and may be a valuable source of information for researchers in pharmacology designing new therapeutic agents.

Abstract

Lupins, like other legumes, have a unique biosynthesis scheme of 5-deoxy-type flavonoids and isoflavonoids. A key enzyme in this pathway is chalcone isomerase (CHI), a member of CHI-fold protein family, encompassing subfamilies of CHI1, CHI2, CHI-like (CHIL), and fatty acid-binding (FAP) proteins. Here, two Lupinus angustifolius (narrow-leafed lupin) CHILs, LangCHIL1 and LangCHIL2, were identified and characterized using DNA fingerprinting, cytogenetic and linkage mapping, sequencing and expression profiling. Clones carrying CHIL sequences were assembled into two contigs. Full gene sequences were obtained from these contigs, and mapped in two L. angustifolius linkage groups by gene-specific markers. Bacterial artificial chromosome fluorescence in situ hybridization approach confirmed the localization of two LangCHIL genes in distinct chromosomes. The expression profiles of both LangCHIL isoforms were very similar. The highest level of transcription was in the roots of the third week of plant growth; thereafter, expression declined. The expression of both LangCHIL genes in leaves and stems was similar and low. Comparative mapping to reference legume genome sequences revealed strong syntenic links; however, LangCHIL2 contig had a much more conserved structure than LangCHIL1. LangCHIL2 is assumed to be an ancestor gene, whereas LangCHIL1 probably appeared as a result of duplication. As both copies are transcriptionally active, questions arise concerning their hypothetical functional divergence. Screening of the narrow-leafed lupin genome and transcriptome with CHI-fold protein sequences, followed by Bayesian inference of phylogeny and cross-genera synteny survey, identified representatives of all but one (CHI1) main subfamilies. They are as follows: two copies of CHI2, FAPa2 and CHIL, and single copies of FAPb and FAPa1. Duplicated genes are remnants of whole genome duplication which is assumed to have occurred after the divergence of Lupinus, Arachis, and Glycine.