A new family of antimicrobial peptides from skin secretions of Rana pleuraden

While conducting experiments to investigate antimicrobial peptides of amphibians living in the Yunnan-Guizhou region of southwest China, a new family of antimicrobial peptides was identified from skin secretions of the Yunnan frog, Rana pleuraden. Members of the new peptide family named pleurain-As are composed of 26 amino acids with a unique N-terminal sequence (SIIT) and a disulfide-bridged heptapeptide sequence (CRLYNTC). By BLAST search, pleurain-As had no significant similarity to any known peptides. Native and synthetic peptides showed antimicrobial activities against tested microorganisms including Gram-negative and Gram-positive bacteria and fungi. Twenty different cDNAs encoding pleurain-As were cloned from the skin cDNA library of R. pleuraden. The precursors of pleurain-As are composed of 69 amino acid residues including predicted signal peptides, acidic propieces, and cationic mature antimicrobial peptides. The preproregion of pleurain-A precursor comprises a hydrophobic signal peptide of 22 residues followed by an 18 residue acidic propiece which terminates by a typical prohormone processing signal Lys-Arg. The preproregions of precursors are very similar to other amphibian antimicrobial peptide precursors but the mature pleurain-As are different from other antimicrobial peptide families. The remarkable similarity of preproregions of precursors that give rise to very different antimicrobial peptides in distantly related frog species suggests that the corresponding genes form a multigene family originating from a common ancestor. Furthermore, pleurain-As could exert antimicrobial capability against Helicobacter pylori. This is the first report of naturally occurring peptides with anti-H. pylori activity from Rana amphibians.     

Evolution of the Hedgehog Gene Family

Effective intercellular communication is an important feature in the development of multicellular organisms. Secreted hedgehog (hh) protein is essential for both long- and short-range cellular signaling required for body pattern formation in animals. In a molecular evolutionary study, we find that the vertebrate homologs of the Drosophila hh gene arose by two gene duplications: the first gave rise to Desert hh, whereas the second produced the Indian and Sonic hh genes. Both duplications occurred before the emergence of vertebrates and probably before the evolution of chordates. The amino-terminal fragment of the hh precursor, crucial in long- and short-range intercellular communication, evolves two to four times slower than the carboxyl-terminal fragment in both Drosophila hh and its vertebrate homologues, suggesting conservation of mechanism of hh action in animals. A majority of amino acid substitutions in the amino- and carboxyl-terminal fragments are conservative, but the carboxyl-terminal domain has undergone extensive insertion-deletion events while maintaining its autocleavage protease activity. Our results point to similarity of evolutionary constraints among sites of Drosophila and vertebrate hh homologs and suggest some future directions for understanding the role of hh genes in the evolution of developmental complexity in animals.     

A DNA Vaccine Encoding a Codon-Optimized Human Papillomavirus Type 16 E6 Gene Enhances CTL Response and Anti-tumor Activity

Summary The HPV oncoproteins E6 and E7 are consistently expressed in HPV-associated cancer cells and are responsible for their malignant transformation. Therefore, HPV E6 and E7 are ideal target antigens for developing vaccines and immunotherapeutic strategies against HPV-associated neoplasms. Recently, it has been demonstrated that codon optimization of the HPV-16 E7 gene resulted in highly efficient translation of E7 and increased the immunogenicity of E7-specific DNA vaccines. Since vaccines targeting E6 also represent an important strategy for controlling HPV-associated lesions, we developed a codon-optimized HPV-16 E6 DNA vaccine (pNGVL4a-E6/opt) and characterized the E6-specific CD8⁺ T cell immune responses as well as the protective and therapeutic anti-tumor effects in vaccinated C57BL/6 mice. Our data indicated that transfection of human embryonic kidney cells (293 cells) with pNGVL4a-E6/opt resulted in highly efficient translation of E6. In addition, vaccination with pNGVL4a-E6/opt significantly enhanced E6-specific CD8⁺ T cell immune responses in C57BL/6 mice. Mice vaccinated with pNGVL4a-E6/opt are able to generate potent protective and therapeutic antitumor effects against challenge with E6-expressing tumor cell line, TC-1. Thus, DNA vaccines encoding a codon-optimized HPV-16 E6 may be a promising strategy for improving the potency of prophylactic and therapeutic HPV vaccines with potential clinical implications.     

Copper redistribution in Atox1-deficient mouse fibroblast cells

Quantitative synchrotron X-ray fluorescence (SXRF) imaging of adherent mouse fibroblast cells deficient in antioxidant-1 (Atox1), a metallochaperone protein responsible for delivering Cu to cuproenzymes in the trans-Golgi network, revealed striking differences in the subcellular Cu distribution compared with wild-type cells. Whereas the latter showed a pronounced perinuclear localization of Cu, the Atox1-deficient cells displayed a mostly unstructured and diffuse distribution throughout the entire cell body. Comparison of the SXRF elemental maps for Zn and Fe of the same samples showed no marked differences between the two cell lines. The data underscore the importance of Atox1, not only as a metallochaperone for delivering Cu to cuproenzymes, but also as a key player in maintaining the proper distribution and organization of Cu at the cellular level.     

Purification and characterization of high antioxidant peptides from duck egg white protein hydrolysates

The hydrolysate from duck egg white protein (DEWP) prepared by “SEEP–Alcalase” at degree of hydrolysis (DH) value of 21% (namely HSA₂₁) exhibited high antioxidant capacity in different oxidation systems. A consecutive chromatographic method was then developed for separation and purification of HSA₂₁, including ion-exchange chromatography, macroporous adsorption resin (MAR) and gel filter chromatography. The final peptides “P_21-3–75-B” were obtained with significantly enhanced antioxidant activity (p < 0.05). It was further confirmed that the product mainly consisted of five oligopeptides (Mr: 202.1, 294.1, 382.1, 426.3, and 514.4 Da). Furthermore, the antioxidant activity of P_21-3–75-B kept stable after in vitro digestive simulation. Antioxidant capacity of the purified peptides was closely related to the molecular mass, hydrophobic amino acid residues, acidic amino acid and some antioxidant amino acids. This research provided a valuable route for producing new natural-source peptides with strong antioxidant capacity and high nutritious value for our daily intake.     

Determination of the secondary structure of and cellular protein binding to the 3'-untranslated region of the hepatitis C virus RNA genome.

Hepatitis C virus (HCV) contains a positive-stranded RNA genome of approximately 9.5 kb. Despite the overall sequence diversity among individual HCV isolates, the 3'-end 98 nucleotides (nt) of the HCV RNA, which constitute part of the 3'-untranslated region (3'-UTR), are highly conserved. This conserved region may contain the cis-acting signals for RNA replication involving possibly both viral and cellular proteins. We carried out RNase digestion studies, which revealed that this 98-nt region contains three stem-loops but may also assume alternative structures. We further performed UV cross-linking experiments to detect cellular proteins that bound to this region. A 58-kDa cellular protein (p58) was detected. Its binding site was mapped to the stem-loops 2 and 3, which are the most conserved region of the 3'-UTR. Site-directed mutagenesis studies revealed that both stem structures and specific nucleotide sequence within the two loops are important for p58 binding. Mutations that disrupted stem structures abolished protein binding, while the compensatory mutations restored its binding. This region also contains partial sequence similarity to the reported consensus binding sequence for polypyrimidine tract-binding protein (PTB) (a 57-kDa protein). The UV-cross-linked protein could be immunoprecipitated with the anti-PTB antibody, and the recombinant PTB bound to the HCV 3'-UTR with the same binding specificity as p58, establishing that this protein is PTB. However, the reported PTB-binding sequence was not sufficient, but rather the entire stem-loops 2 and 3 were required, for PTB binding; thus, its binding specificity is significantly different from the reported PTB-binding sequence requirement. This protein was detected in both the nuclei and cytoplasm of most mammalian cell lines tested and human primary hepatocytes. PTB may participate in the regulation of HCV RNA synthesis or translation.     

MST1 promotes apoptosis through phosphorylation of histone H2AX

MST1 (mammalian STE20-like kinase 1) is a serine/threonine kinase that is cleaved and activated by caspases during apoptosis. Overexpression of MST1 induces apoptotic morphological changes such as chromatin condensation, but the mechanism is not clear. Here we show that MST1 induces apoptotic chromatin condensation through its phosphorylation of histone H2AX at Ser-139. During etoposide-induced apoptosis in Jurkat cells, the cleavage of MST1 directly corresponded with strong H2AX phosphorylation. In vitro kinase assay results showed that MST1 strongly phosphorylates histone H2AX. Western blot and kinase assay results with a mutant S139A H2AX confirmed that MST1 phosphorylates H2AX at Ser-139. Direct binding of MST1 and H2AX can be detected when co-expressed in HEK293 cells and was also confirmed by an endogenous immunoprecipitation study. When overexpressed in HeLa cells, both the MST1 full-length protein and the MST1 kinase domain (MST1-NT), but not the kinase-negative mutant (MST1-NT-KN), could induce obvious endogenous histone H2AX phosphorylation. The caspase-3 inhibitor benzyloxycarbonyl-DEVD-fluoromethyl ketone (Z-DEVD-fmk) attenuates phosphorylation of H2AX by MST1 but cannot inhibit MST1-NT-induced histone H2AX phosphorylation, indicating that cleaved MST1 is responsible for H2AX phosphorylation during apoptosis. Histone H2AX phosphorylation and DNA fragmentation were suppressed in MST1 knockdown Jurkat cells after etoposide treatment. Taken together, our data indicated that H2AX is a substrate of MST1, which functions to induce apoptotic chromatin condensation and DNA fragmentation.     

Environmental Supply Chain Cooperation and Its Effect on the Circular Economy Practice‐Performance Relationship Among Chinese Manufacturers

Due to resource scarcity and environmental degradation, a new development concept emphasizing environmental concerns, called the circular economy (CE), has been enacted in legislation in China. This environmental management concept can be implemented at three levels, namely, region, industrial zone, and individual enterprise, with the objective of boosting economic development while lessening environmental and resource challenges. Environmental supply chain cooperation (ESCC), an approach that utilizes customer and supplier cooperation in environmental management, has been initiated among Chinese enterprises. Using survey data collected from 396 Chinese manufacturers, we examine the role of ESCC practices in influencing the relationship between implementing CE practices and the achievement of performance outcomes by testing the moderation and mediation effects of ESCC practices on the CE practice‐performance relationship through hierarchical regression analysis. Our data analyses indicate that ESCC practices are useful by moderation and, in some cases, essential by mediation, for Chinese manufacturers seeking to realize the performance targets desired in CE practices. The results highlight the need for Chinese manufacturers to improve supply chain coordination in their implementation of CE. On the policy side, our research findings suggest that ESCC practices are beneficial and, in some cases, necessary for the development of CE in China.     

P. falciparum RH5‐Basigin interaction induces changes in the cytoskeleton of the host RBC

The successful invasion of Plasmodium is an essential step in their life cycle. The parasite reticulocyte‐binding protein homologues (RHs) and erythrocyte‐binding like proteins are two families involved in the invasion leading to merozoite‐red blood cell (RBC) junction formation. Ca²⁺ signaling has been shown to play a critical role in the invasion. RHs have been linked to Ca²⁺ signaling, which triggers the erythrocyte‐binding like proteins release ahead of junction formation, consistent with RHs performing an initial sensing function in identifying suitable RBCs. RH5, the only essential RHs, is a highly promising vaccine candidate. RH5‐basigin interaction is essential for merozoite invasion and also important in determining host tropism. Here, we show that RH5 has a distinct function from the other RHs. We show that RH5‐Basigin interaction on its own triggers a Ca²⁺ signal in the RBC resulting in changes in RBC cytoskeletal proteins phosphorylation and overall alterations in RBC cytoskeleton architecture. Antibodies targeting RH5 that block the signal prevent invasion before junction formation consistent with the Ca²⁺ signal in the RBC leading to rearrangement of the cytoskeleton required for invasion. This work provides the first time a functional context for the essential role of RH5 and will now open up new avenues to target merozoite invasion.