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Abstract: The endosomal escape is a well-known serious obstacle for non-viral gene delivery. This is because of an acidic and enzymatic degradation of the contents of the endosome/lysosome. Therefore, the internalized gene needs to be efficient released into the cytosol to obtain the efficiently transfection efficiency. On the other hand, the diphtheria toxin T domain fuses with endosome membrane by pH decrease, then enhances the endosomal escape of the diphtheria toxin C fragment. In this study, we constructed diphtheria toxin T domain-conjugated poly(ethylenimine)s (PEI) polyplex for enhancing the endosomal escape of exogenous gene. The conjugation of diphtheria toxin T domain with PEI/pDNA polyplex leads to the significant enhancement of transfection efficiency when compared with plain PEI/pDNA polyplex. The pH-responsive increase in hydrophobicity of the diphtheria toxin T domain might not only trigger the perturbation of the endocytic vesicle membrane but might also increase the membrane permeability. [Copyright &y& Elsevier]

We observed the dynamics of peeling of giant multilamellar vesicles interacting with a solid–liquid interface by using phase-contrast microscopy. When a multilamellar vesicle touches a surface, the outer layer peels away and the inner layer is exposed. There are two distinct pathways for this shape transformation that depend on the size of the vesicle. We theoretically discuss the mechanism and kinetics of peeling by considering the surface energy, line energy and bending energy. [Copyright &y& Elsevier]

Highlights: [•] Lytic peptide penetrated the lipid membranes of GUV without pore formation. [•] We observed colocalization between lytic peptide and endosome marker EEA-1 in cells. [•] The lytic peptide localized on mitochondria. [•] Endocytosis inhibitors decreased uptake and cytotoxic activity of lytic peptide. [ABSTRACT FROM AUTHOR]

Abstract: Amyloid beta (Aβ) peptides, produced through endo-proteolytic cleavage of amyloid precursor protein, are thought to be involved in the death of neural cells in Alzheimer''s disease (AD). Although the mechanisms are not fully known, it has been suggested that disruption of cellular activity due to Aβ interactions with the cell membrane may be one of the underlying causes. Here in, we have investigated the interaction between Aβ-42 and biomimetic lipid membranes and the resulting perturbations in the lipid vesicles. We have shown that Aβ oligomeric species localized closer to the membrane surface. Localization of the fibrillar species of Aβ-42, although varied, was not as closely associated with the membrane surface. We have demonstrated that the presence of Aβ-42 leads to an increase in membrane surface area, inducing lipid temporal vesicular transformation. Furthermore, we have unequivocally shown that Aβ-peptides mediate membrane fusion. Although membrane fusion induced by Aβ has been hypothesized/proposed, this is the first time it has been visually captured. This fusion may be one of the mechanisms behind the membrane increase in surface area and the resulting vesicular transformation. We have shown that the longer ‘amyloidogenic’ isoform causes vesicular transformation more readily, and has a higher membrane fusogenic potential than Aβ-40. Although not core to this study, it is hugely interesting to observe the high agreement between membrane dynamics and the reported amyloidogenicity of the peptides and aggregation species opening up the potential role of vesicular dynamics for profiling and biosensing of Aβ-induced neuro-toxicity. [Copyright &y& Elsevier]

Abstract: The effect of temperature change(s) on the dynamics of giant unilamellar vesicles containing oxidized and non-oxidized cholesterol was investigated and characterized. We have demonstrated that (i) major cholesterol auto-oxidation products, 7β-hydroxycholesterol (7β) and 7-ketocholesterol (7keto), rendered vesicles more responsive to temperature changes; (ii) 7keto imparted greater thermo-induced membrane dynamics than 7β; (iii) 7β and 7keto vesicles synergistically were more thermo-responsive than the individual oxysterols; (iv) the thermo-responsiveness of 7keto-containing vesicles was equivalent to that of 25 hydroxycholesterol (25OH)-containing vesicles; and (v) we have characterized the observed membrane dynamics. The results provide a new plausible mechanism: oxidative-stressed membranes in conjunction with temperature change induce membrane dynamics. These findings improve the mechanisms reported previously that attributed the induced dynamics solely to membrane oxidation. [Copyright &y& Elsevier]

Abstract: The interaction of amyloid beta (Aβ) peptide with cell membranes has been shown to be influenced by Aβ conformation, membrane physicochemical properties and lipid composition. However, the effect of cholesterol and its oxidized derivatives, oxysterols, on Aβ-induced neurotoxicity to membranes is not fully understood. We employed here model membranes to investigate the localization of Aβ in membranes and the peptide-induced membrane dynamics in the presence of cholesterol and 7-ketocholesterol (7keto) or 25-hydroxycholesterol (25OH). Our results have indicated that oxysterols rendered membranes more sensitive to Aβ, in contrast to role of cholesterol in inhibiting Aβ/membrane interaction. We have demonstrated that two oxysterols had different impacts owing to distinct positions of the additional oxygen group in their structures. 7keto-containing cell-sized liposomes exhibited a high propensity toward association with Aβ, while 25OH systems were more capable of morphological changes in response to the peptide. Furthermore, we have shown that 42-amino acid Aβ (Aβ-42) pre-fibril species had higher association with membranes, and caused membrane fluctuation faster than 40-residue isoform (Aβ-40). These findings suggest the enhancing effect of oxysterols on interaction of Aβ with membranes and contribute to clarify the harmful impact of cholesterol on Aβ-induced neurotoxicity by means of its oxidation. [Copyright &y& Elsevier]

Abstract: CL(14-25), a dodecapeptide, that is a partial region near N-terminus of cyanate lyase (CL, EC 4.3.99.1) from rice (Oryza sativa L. japonica), contains three arginine and two lysine residues. It was a novel cationic α-helical antimicrobial peptide. The antimicrobial activity of CL(14-25) against Porphyromonas gingivalis, a periodontal pathogen, was quantitatively evaluated by a chemiluminescence method that measures ATP derived from viable cells. The 50% growth-inhibitory concentration of CL(14-25) against P. gingivalis cells was 145μM. CL(14-25), even at a concentration of 800μM, had no hemolytic activity. When giant unilamellar vesicles (GUVs) that mimic the membrane composition of Gram-negative bacteria were used, microscopy image analysis suggested that CL(14-25) disrupted GUVs in a detergent-like manner. Therefore, CL(14-25) appears to exhibit antimicrobial activity through membrane disruption. To investigate the contribution of cationic amino acid residues in CL(14-25) to its antimicrobial activity, we synthesized four truncated CL analogs, in which one or two cationic amino acid residues were deleted from the N- and C- termini of CL(14-25). The degrees of calcein leakage from large unilamellar vesicles (LUVs) and 3,3′-dipropylthiadicarbocyanine iodide (diSC3-5) release from P. gingivalis cells induced by truncated CL analogs were closely related to their antimicrobial activities. CL analogs, which were truncated by removing an arginine residue from the N-terminus and a lysine residue from the C-terminus maintained their antimicrobial activity. However, CL analogs, which were further truncated by removing two arginine residues from the N-terminus, and an arginine and a lysine residue from the C-terminus, rarely exhibited antimicrobial activity. [Copyright &y& Elsevier]

Abstract: Our previous study reported a frequent detection of human papillomavirus (HPV) genome in primary lung adenocarcinomas of the recurrent patients who were responsive to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor, suggesting that HPV presence in lung cancer may be related to a genetic background related to EGFR mutations. The present study examined the association between the HPV presence and mutations in exons 19 and 21 of EGFR gene in Japanese lung cancer patients. Thirteen (31%) out of 42 cases had EGFR mutations. Although these mutations were tended to be observed in females, non-smokers, or adenocarcinomas, there was no statistically significant associations. HPV DNA was found in 7/42 (17%) lung tumors. The frequency of HPV presence did not differ in histological types. The presence of HPV DNA was significantly related to EGFR mutations (P =0.021), especially in adenocarcinomas of the lung (P =0.014). HPV-positive lung tumors accounted for 38% and 7% of those with and without EGFR mutations, respectively. Our results suggest that EGFR mutations are associated with HPV presence in Japanese patients with lung cancer. [Copyright &y& Elsevier]