Human SCARB2 Transgenic Mice as an Infectious Animal Model for Enterovirus 71

Enterovirus 71 (EV71) and coxsackievirus (CVA) are the most common causative factors for hand, foot, and mouth disease (HFMD) and neurological disorders in children. Lack of a reliable animal model is an issue in investigating EV71-induced disease manifestation in humans, and the current clinical therapies are symptomatic. We generated a novel EV71-infectious model with hSCARB2-transgenic mice expressing the discovered receptor human SCARB2 (hSCARB2). The challenge of hSCARB2-transgenic mice with clinical isolates of EV71 and CVA16 resulted in HFMD-like and neurological syndromes caused by E59 (B4) and N2838 (B5) strains, and lethal paralysis caused by 5746 (C2), N3340 (C4), and CVA16. EV71 viral loads were evident in the tissues and CNS accompanied the upregulated pro-inflammatory mediators (CXCL10, CCL3, TNF-α, and IL-6), correlating to recruitment of the infiltrated T lymphocytes that result in severe diseases. Transgenic mice pre-immunized with live E59 or the FI-E59 vaccine was able to resist the subsequent lethal challenge with EV71. These results indicate that hSCARB2-transgenic mice are a useful model for assessing anti-EV71 medications and for studying the pathogenesis induced by EV71.     

Betel nut extract and arecoline block insulin signaling and lipid storage in 3T3-L1 adipocytes

According to several population-based studies, betel nut chewing is associated with metabolic syndrome and diabetes in British South Asians and Taiwanese. However, the underlying molecular mechanism is not yet clear. Arecoline is an alkaloid-type natural product found in betel nuts. Our aim was to clarify the influence of betel nut extract and arecoline on lipid accumulation and insulin signaling in adipocytes. We found that betel nut extract and arecoline blocked lipid storage in 3T3-L1 adipocytes. The possible mechanism may function by inhibiting the expression of the insulin receptor, glucose transporter-4, fatty acid synthase, and the lipid droplet proteins perilipin and adipophilin. In addition, betel nut extract and arecoline increased the basal level of IRS-1 serine³⁰⁷ phosphorylation and decreased insulin-stimulated IRS-1 tyrosine, Akt, and PI3 kinase phosphorylation. In conclusion, betel nut extract and arecoline have diabetogenic potential on adipocytes that may result in insulin resistance and diabetes at least in part via the obstruction of insulin signaling and the blockage of lipid storage.     

Actin in mung bean mitochondria and implications for its function

Here, a large fraction of plant mitochondrial actin was found to be resistant to protease and high-salt treatments, suggesting it was protected by mitochondrial membranes. A portion of this actin became sensitive to protease or high-salt treatment after removal of the mitochondrial outer membrane, indicating that some actin is located inside the mitochondrial outer membrane. The import of an actin-green fluorescent protein (GFP) fusion protein into the mitochondria in a transgenic plant, actin:GFP, was visualized in living cells and demonstrated by flow cytometry and immunoblot analyses. Polymerized actin was found in mitochondria of actin:GFP plants and in mung bean (Vigna radiata). Notably, actin associated with mitochondria purified from early-developing cotyledons during seed germination was sensitive to high-salt and protease treatments. With cotyledon ageing, mitochondrial actin became more resistant to both treatments. The progressive import of actin into cotyledon mitochondria appeared to occur in concert with the conversion of quiescent mitochondria into active forms during seed germination. The binding of actin to mitochondrial DNA (mtDNA) was demonstrated by liquid chromatography-tandem mass spectrometry analysis. Porin and ADP/ATP carrier proteins were also found in mtDNA-protein complexes. Treatment with an actin depolymerization reagent reduced the mitochondrial membrane potential and triggered the release of cytochrome C. The potential function of mitochondrial actin and a possible actin import pathway are discussed.     

Chemical constituents of the fermented broth of the ascomycete Theissenia cinerea 89091602

One new betaenone, theissenoic acid (1), together with three new acetogenins, theissenolactones A-C (2-4, resp.), were isolated from the fermented broth of Theissenia cinerea 89091602 isolated in Taiwan. The structures of 1-4 were elucidated by spectroscopic methods. Biological tests revealed that 3 and 4 exhibited moderate growth-inhibitory activities against A549 lung cancer cell line with GI(50) values of 14.9 and 47.9 μM, respectively.     

Anticancer activities of an antimicrobial peptide derivative of Ixosin-B amide

In nature, antimicrobial peptides (AMPs) represent the first line of defense against infection by pathogens; thus, they are generally good candidates for the development of antimicrobial agents. Recently, we reported two potent antimicrobial peptides, KWLRRVWRWWR-amide (MAP-04-03) and KRLRRVWRRWR-amide (MAP-04-04), which were derived from a fragment of Ixosin-B-amide (KSDVRRWRSRY). Since some cationic AMPs exhibited cytotoxic activity against cancer cells, in the current study, we further investigated the anticancer activity of these potent antimicrobial peptides by antiproliferative assays and wound-healing assays, and the effect of peptide on the cytoskeleton alteration and cell morphology were analyzed by confocal microscopy. Results indicated that MAP-04-03 not only exhibited inhibitory effects on the proliferation (IC₅₀ = 61.5 μM) and on the cell migration of MCF-7 breast cancer cells (at a concentration of 5 μM), but also affected the cytoskeleton at the concentration of 25 μM. These results demonstrated that MAP-04-03 can serve as a lead peptide analog for developing potent anticancer agents.     

EGFR-driven up-regulation of decoy receptor 3 in keratinocytes contributes to the pathogenesis of psoriasis

Decoy receptor 3 (DcR3) is a soluble receptor of Fas ligand (FasL), LIGHT (TNFSF14) and TNF-like molecule 1A (TL1A) and plays pleiotropic roles in many inflammatory and autoimmune disorders and malignant diseases. In cutaneous biology, DcR3 is expressed in primary human epidermal keratinocytes and is upregulated in skin lesions in psoriasis, which is characterized by chronic inflammation and angiogenesis. However, the regulatory mechanisms of DcR3 over-expression in skin lesions of psoriasis are unknown. Here, we demonstrate that DcR3 can be detected in both dermal blood vessels and epidermal layers of psoriatic skin lesions. Analysis of serum samples showed that DcR3 was elevated, but FasL was downregulated in psoriatic patients compared with normal individuals. Additional cell studies revealed a central role of epidermal growth factor receptor (EGFR) in controlling the basal expression of DcR3 in keratinocytes. Activation of EGFR by epidermal growth factor (EGF) and transforming growth factor (TGF)-α strikingly upregulated DcR3 production. TNF-α?enhanced DcR3 expression in both keratinocytes and endothelial cells compared with various inflammatory cytokines involved in psoriasis. Additionally, TNF-α-enhanced DcR3 expression in keratinocytes was inhibited when EGFR was knocked down or EGFR inhibitor was used. The NF-κB pathway was critically involved in the molecular mechanisms underlying the action of EGFR and inflammatory cytokines. Collectively, the novel regulatory mechanisms of DcR3 expression in psoriasis, particularly in keratinocytes and endothelial cells, provides new insight into the pathogenesis of psoriasis and may also contribute to the understanding of other diseases that involve DcR3 overexpression.     

Phosphorylation Drives a Dynamic Switch in Serine/Arginine-Rich Proteins

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Assessment of mechanical integrity for drug-eluting renal stent with micro-sized drug reservoirs

The drug-eluting stent (DES) has become the gold standard worldwide for the treatment of cardiovascular diseases. In recent years, an innovative variation of the DES with micro-sized drug reservoirs has been introduced. It allows programmable drug delivery with both spatial and temporal control and has several potential advantages over traditional DESs. However, creating such reservoirs on the stent struts may weaken the structure of the stent scaffolding and compromise its mechanical integrity. In this study, we propose to use this innovative stent concept in the renal indication for potential treatment of both renal artery stenosis (upstream) and its associated kidney diseases (downstream) at the same time. The effects of these micro-sized drug reservoirs on several key clinically relevant functional attributes of the drug-eluting renal stent were systematically and quantitatively investigated. Finite element models were developed to predict the mechanical integrity of a balloon-expandable stent at various stages. Results show that (1) creating drug reservoirs on a stent could impact the stent fatigue resistance to certain degrees; (2) drug reservoirs on the stent crowns lead to greater loss in all key stent attributes than reservoirs on either bar arms or connectors and (3) the proposed optimised depot stent was proven to be feasible and could triple drug capacity than the current DESs, with marginal trade-off in its key clinical attributes. These results can serve as the guidelines to help future stent designs to achieve the best combination of stent structural integrity and smart drug delivery in the future.     

Molecular paleontology: a biochemical model of the ancestral ribosome

Ancient components of the ribosome, inferred from a consensus of previous work, were constructed in silico, in vitro and in vivo. The resulting model of the ancestral ribosome presented here incorporates ∼20% of the extant 23S rRNA and fragments of five ribosomal proteins. We test hypotheses that ancestral rRNA can: (i) assume canonical 23S rRNA-like secondary structure, (ii) assume canonical tertiary structure and (iii) form native complexes with ribosomal protein fragments. Footprinting experiments support formation of predicted secondary and tertiary structure. Gel shift, spectroscopic and yeast three-hybrid assays show specific interactions between ancestral rRNA and ribosomal protein fragments, independent of other, more recent, components of the ribosome. This robustness suggests that the catalytic core of the ribosome is an ancient construct that has survived billions of years of evolution without major changes in structure. Collectively, the data here support a model in which ancestors of the large and small subunits originated and evolved independently of each other, with autonomous functionalities.     

Live and dead GFP-tagged bacteria showed indistinguishable fluorescence in Caenorhabditis elegans gut

Caenorhabditis elegans has been used for studying host-pathogen interactions since long, and many virulence genes of pathogens have been successfully identified. In several studies, fluorescent pathogens were fed to C. elegans and fluorescence observed in the gut was considered an indicator for bacterial colonization. However, the grinder in the pharynx of these nematodes supposedly crushes the bacterial cells, and the ground material is delivered to the intestine for nutrient absorption. Therefore, it remains unclear whether intact bacteria pass through the grinder and colonize in the intestine. Here we investigated whether the appearance of fluorescence is indicative of intact bacteria in the gut using both fluorescence microscopy and transmission electron microscopy. In wild-type N2 C. elegans, Escherichia coli DH5α, and Vibrio vulnificus 93U204, both of which express the green fluorescence protein, were found intact only proximal to the grinder, while crushed bacterial debris was found in the post-pharyngeal lumen. Nevertheless, the fluorescence was evident throughout the lumen of worm intestines irrespective of whether the bacteria were intact or not. We further investigated the interaction of the bacteria with C. elegans phm-2 mutant, which has a dysfunctional grinder. Both strains of bacteria were found to be intact and accumulated in the pharynx and intestine owing to the defective grinder. The fluorescence intensity of intact bacteria in phm-2 worms was indistinguishable from that of crushed bacterial debris in N2 worms. Therefore, appearance of fluorescence in the C. elegans intestine should not be directly interpreted as successful bacterial colonization in the intestine.