Multiple Functions of Short Synthetic Enantiomeric Peptides Based on Beetle Defensins

The draft genome sequence of the Japanese rhinoceros beetle Trypoxylus dichotomus septentrionalis towards an understanding of horn formation

The Japanese rhinoceros beetle Trypoxylus dichotomus is a giant beetle with distinctive exaggerated horns present on the head and prothoracic regions of the male. T. dichotomus has been used as a research model in various fields such as evolutionary developmental biology, ecology, ethology, biomimetics, and drug discovery. In this study, de novo assembly of 615 Mb, representing 80% of the genome estimated by flow cytometry, was obtained using the 10 × Chromium platform. The scaffold N50 length of the genome assembly was 8.02 Mb, with repetitive elements predicted to comprise 49.5% of the assembly. In total, 23,987 protein-coding genes were predicted in the genome. In addition, de novo assembly of the mitochondrial genome yielded a contig of 20,217 bp. We also analyzed the transcriptome by generating 16 RNA-seq libraries from a variety of tissues of both sexes and developmental stages, which allowed us to identify 13 co-expressed gene modules. We focused on the genes related to horn formation and obtained new insights into the evolution of the gene repertoire and sexual dimorphism as exemplified by the sex-specific splicing pattern of the doublesex gene. This genomic information will be an excellent resource for further functional and evolutionary analyses, including the evolutionary origin and genetic regulation of beetle horns and the molecular mechanisms underlying sexual dimorphism.

Anti-angiogenesis activities of novel peptide complexes: mitochondria-disruptive 9mer peptides conjugated with the integrin alpha V beta 3-homing cyclic RGD motif

RGD peptides are popular drug delivery tools in treating integrin αVβ3-expressing malignant tumors and tumor vasculature cells. We investigated the specific delivery and pharmacological potential of enantiomeric mitochondria-disruptive peptides (RLYLRIGRR-NH(2), RLRLRIGRR-NH(2), ALYLAIRRR-NH(2), and RLLLRIGRR-NH(2)) after conjugation with an integrin αVβ3-homing peptide, cyclic pentameric RGD peptide. The cyclic RGD-conjugated mitochondria-disruptive peptides exhibited specific internalization, apoptosis induction, and cytotoxicity against integrin αVβ3-high-expressing human umbilical vein endothelial cells. Our findings indicate that these novel peptide complexes might prove good anti-angiogenesis reagents.

Characterization of dual effects induced by antimicrobial peptides: regulated cell death or membrane disruption

BACKGROUND

Some reports describe lysis mechanisms by antimicrobial peptides (AMPs), while others describe the activation of regulated cell death. In this study, we compare the cell death-inducing activities of four β-hairpin AMPs (gomesin, protegrin, tachyplesin and polyphemusin II) along with their linear analogs in the human erythroleukemia K562 cell line to investigate the relationship between their structure and activity.

METHODS

K562 cells were exposed to AMPs. Morphological and biochemistry alterations were evaluated using light microscopy, confocal microscopy and flow cytometry.

RESULTS

Gomesin and protegrin displayed cytotoxic properties that their linear counterparts did not. Tachyplesin and polyphemusin II and also their linear analogs induced cell death. We were able to distinguish two ways in which these AMPs induced cell death. Lower concentrations of AMPs induced controlled cell death mechanisms. Gomesin, tachyplesin and linear-tachyplesin promoted apoptosis that was characterized by annexin labeling, sensitivity to Z-VAD, and caspase-3 activation, but was also inhibited by necrostatin-1. Gomesin and protegrin induced cell death was dependent on intracellular Ca2+ mechanisms and the participation of free radicals was observed in protegrin induced cell death. Polyphemusin II and its linear analog mainly induced necrosis. Conversely, treatment with higher concentrations of AMPs primarily resulted in cell membrane disruption, but with clearly different patterns of action for each AMP tested.

CONCLUSION

Different actions by β-hairpin AMPs were observed at low concentrations and at higher concentrations despite the structure similarity.

GENERAL SIGNIFICANCE

Controlled intracellular mechanism and direct membrane disruption were clearly distinguished helping to understand the real action of AMPs in mammalian cells.

Development of a bioactive fiber with immobilized synthetic peptides designed from the active site of a beetle defensin

The 9-mer peptides RLYLRIGRR and RLLLRIGRR were immobilized to amino-functionalized cotton fibers by a modification of the SPOT synthesis technique. The antibacterial activities of the peptide-immobilized cotton fibers against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) were investigated. Antibacterial assays revealed that these fibers inhibit the growth of MRSA and the antibacterial activities were maintained after washing and sterilization by autoclaving. The anticancer effect of the peptide-immobilized fiber was also investigated with mouse myeloma cells and human leukemia cells. These results indicate that these fibers have strong growth inhibition activity against bacteria and cancer cells.