Simultaneous imaging and restoration of cell function using cell permeable peptide probe

Cytosolic Delivery of Functional Ubiquitin

The proteostasis network involves complex protein signaling cascades. The tagging of proteins with ubiquitin is central to the degradation of cellular proteins, but understanding its exact role in processing proteins is complicated by the complexity and extent of its utilization within cells. Here, we describe the application of a traceless protein delivery strategy to effect the uptake of exogenous ubiquitin into the cytosol of human cells. We find that coadministration of the endosomolytic peptides L17E and, especially, L17ER4 provides not only cytosolic access to ubiquitin but also its functional incorporation into endogenous proteins. By enabling the study of semisynthetic ubiquitin variants in the human cytosol, this strategy could advance the field of ubiquitin biology.

Cell penetrating peptides are versatile tools for enhancing multimodal uptake into cells from pest insects

Cell penetrating peptides (CPPs) are small peptides defined by their ability to deliver molecular cargo into cells. While the subject of frequent investigation for pharmaceutical drug delivery, little consideration has been given to the possibility of CPPs for use as insecticides or insecticide enhancers. Here, we characterize the entry of four fluorescently tagged CPPs into two insect cell lines and dissected midgut tissues in terms of both total quantity and mode of penetration. Fluorescent microscopy showed that substantial amounts of CPPs penetrate the plasma membrane via endosomal uptake in ovarian (Sf9) and midgut derived (AW1) lepidopteran cells and that this process was sensitive to selected endocytosis inhibitors. Differences in the quantity of uptake was observed between CPPs, and further differences were found in the ability CPP-1838 to efficiently penetrate membranes through passive diffusion. These findings were extended to primary midgut derived cells and dissected tissues suggesting that CPPs show a preference for goblet cells and that CPP-1838 shows far higher rates of penetration. CPP-1838 thus shows extraordinary abilities to penetrate cells efficiency in both a diffusional and endocytotic manner. From these results more sophisticated delivery methods based on the utilization of CPPs can be developed.

Engineered synthetic cell penetrating peptide with intracellular anti-inflammatory bioactivity: An in vitro and in vivo study

Various biomaterials have been used for bone and cartilage regeneration, and inflammation associated with biomaterial implantation is also increased. A 15-mer synthetic anti-inflammatory peptide (SAP15) was designed from human β-defensin 3 to penetrate cells and induce intracellular downregulation of inflammation. The downregulation of inflammation was achieved by the binding of SAP15 to intracellular histone deacetylase (HDAC5). SAP15-mediated inhibition of inflammation was examined in vitro and in vivo using murine macrophages, human articular chondrocytes, and a collagen-induced arthritis (CIA) rat model. Surface plasmon resonance and immunoprecipitation assays indicated that SAP15 binds to HDAC5. SAP15 inhibited the lipopolysaccharide (LPS)-induced phosphorylation of intracellular HDAC5 and NF-κB p65 in murine macrophages. SAP15 treatment increased aggrecan and type II collagen expression and decreased osteocalcin expression in LPS-induced chondrocytes. Subcutaneous injection of SAP15-loaded sodium hyaluronic acid (HA) solution significantly decreased hind paw swelling, joint inflammation, and serum cytokine levels in CIA rats compared with the effects of sodium HA solution alone. The SAP15-loaded HA group exhibited preservation of cartilage and bone structure in CIA rat joints. Moreover, a more robust anti-inflammatory effect of the SAP15 loaded HA was observed than that of etanercept (an anti-tumor necrosis factor-alpha [TNF-α] antibody)-loaded HA. These findings suggest that SAP15 has an anti-inflammatory effect that is not controlled by sodium HA and is mediated by inhibiting HDAC5, unlike the anti-inflammatory mechanism of etanercept. These results demonstrate that SAP15 is useful as an inflammatory regulator of biomaterials and can be developed as a therapeutic for the treatment of inflammation.

Control of cancer stem cell like population by intracellular target identification followed by the treatment with peptide-siRNA complex

Cancer stem cells (CSCs) are a subpopulation of cancer cells and have been known to create cancer reoccurrence during cancer therapy due to their stem cell-like characteristics. However, exact target to control the CSC has not been fully established. Here, we enriched CD44^High population of MDA-MB-231 cells by CD44 antibody as a CSC marker. By Phospho Antibody Array, CD44^High population of MDA-MB-231 cells reveals Feline sarcoma-related tyrosine kinase (FER) protein was highly activated. When FER siRNA and low molecular weight protamine (LMWP) as cell penetrating peptides are applied to this population, cancer migration and colony forming ability are inhibited. Moreover, silencing FER using FER siRNA and LMWP conjugates enhances anti-metastasis related factors including E-cadherin, p75 and p63. Taken together, FER is a new marker for targeting breast CSCs and peptide-mediated siRNA method could be an effective and safe way of delivery and be a new therapeutic strategy for targeting breast cancer.

Emerging landscape of cell penetrating peptide in reprogramming and gene editing

The plasma membrane remains a major barrier for intracellular drug delivery, to overcome this issue, a variety of approaches have been developed and used to deliver therapeutic cargos. Among these approaches, cell penetrating peptide (CPP) is promising and affords widely used vector for efficient intracellular delivery of cargos. Moreover, the latter findings including iPS reprogramming and direct transdifferentiation as well as gene editing have gradually become hot research topic; because their application in tissue engineering and disease modeling have great potential to advance innovation in precision medicine. Since the beginning, research on these approaches is mainly based on virus transduction system, while, under the consideration for obviating the risk of mutagenic insertion and enables more accurate controlling, CPP-based efficient virus-free delivery strategy has been used recently. In this review, we summarize the existing CPP-based delivery system, emerging landscape of CPP application in stem cell manipulation and reprogramming, along with CPP contributions to gene editing techniques.

Effects of the properties of short peptides conjugated with cell-penetrating peptides on their internalization into cells

Peptides, especially intracellular functional peptides that can play a particular role inside a cell, have attracted attention as promising materials to control cell fate. However, hydrophilic materials like peptides are difficult for cells to internalize. Therefore, the screening and design of intracellular functional peptides are more difficult than that of extracellular ones. An effective high-throughput screening system for intracellular functional peptides has not been reported. Here, we demonstrate a novel peptide array system for screening intracellular functional peptides, in which both cell-penetrating peptide (CPP) domain and photo-cleavable linkers are used. By using this screening system, we determined how the cellular uptake properties of CPP-conjugated peptides varied depending on the properties of the conjugated peptides. We found that the internalization ability of CPP-conjugated peptides varied greatly depending on the property of the conjugated peptides, and anionic peptides drastically decreased the uptake ability. We summarized our data in a scatter diagram that plots hydrophobicity versus isoelectric point (pI) of conjugated peptides. These results define a peptide library suitable for screening of intracellular functional peptides. Thus, our system, including the diagram, is a promising tool for searching biological active molecules such as peptide-based drugs.

Cell-penetrating peptides transport therapeutics into cells

Nearly 30years ago, certain small, relatively nontoxic peptides were discovered to be capable of traversing the cell membrane. These cell-penetrating peptides, as they are now called, have been shown to not only be capable of crossing the cell membrane themselves but can also carry many different therapeutic agents into cells, including small molecules, plasmid DNA, siRNA, therapeutic proteins, viruses, imaging agents, and other various nanoparticles. Many cell-penetrating peptides have been derived from natural proteins, but several other cell-penetrating peptides have been developed that are either chimeric or completely synthetic. How cell-penetrating peptides are internalized into cells has been a topic of debate, with some peptides seemingly entering cells through an endocytic mechanism and others by directly penetrating the cell membrane. Although the entry mechanism is still not entirely understood, it seems to be dependent on the peptide type, the peptide concentration, the cargo the peptide transports, and the cell type tested. With new intracellular disease targets being discovered, cell-penetrating peptides offer an exciting approach for delivering drugs to these intracellular targets. There are hundreds of cell-penetrating peptides being studied for drug delivery, and ongoing studies are demonstrating their success both in vitro and in vivo.

Cell-penetrating peptides: strategies for anticancer treatment

Cell-penetrating peptides (CPP) provide an efficient strategy for the intracellular delivery of bioactive molecules in various biomedical applications. This review focuses on recent advances in the use of CPPs to deliver anticancer therapeutics and imaging reagents to cancer cells, along with CPP contributions to novel tumor-targeting techniques. CPPs are now used extensively to deliver a variety of therapeutics, despite lacking cell specificity and having a short duration of action. Resolution of these shortcomings to enable increased cancer cell and/or tumor specificity could improve CPP-based drug delivery strategies, expand combined drug delivery possibilities, and strengthen future clinical applications of these peptides.