We show that human adenovirus inhibits RNA interference (RNAi) at late times of infection by suppressing the activity of two key enzyme systems involved, Dicer and RNA-induced silencing complex (RISC). To define the mechanisms by which adenovirus blocks RNAi, we used a panel of mutant adenoviruses defective in virus-associated (VA) RNA expression. The results show that the virus-associated RNAs, VA RNAI and VA RNAII, function as suppressors of RNAi by interfering with the activity of Dicer. The VA RNAs bind Dicer and function as competitive substrates squelching Dicer. Further, we show that VA RNAI and VA RNAII are processed by Dicer, both in vitro and during a lytic infection, and that the resulting short interfering RNAs (siRNAs) are incorporated into active RISC. Dicer cleaves the terminal stem of both VA RNAI and VA RNAII. However, whereas both strands of the VA RNAI-specific siRNA are incorporated into RISC, the 3 strand of the VA RNAII-specific siRNA is selectively incorporated during a lytic infection. In summary, our work shows that adenovirus suppresses RNAi during a lytic infection and gives insight into the mechanisms of RNAi suppression by VA RNA.

Aims:  To investigate the antibacterial mechanism of carvacrol and thymol against Escherichia coli. Methods and Results:  The time‐kill curve results showed that carvacrol and thymol at 200 mg l−1 could inhibit the growth of E. coli. Flow cytometry and fluorescent dyes were used to explore the effect of two components on membrane permeability and membrane potential. In membrane permeability experiment, the mean fluorescence intensity of cells treated with 200 mg l−1 carvacrol or thymol were lower than nonexposed cells. The ratio of red to green fluorescence intensity of DiOC2(3) reflected the change of membrane potential. Carvacrol and thymol at 200 mg l−1 caused the ratio of red/green decreasing from 0·42 of control to 0·08 and 0·07, respectively. Conclusions:  Carvacrol and thymol had desired antimicrobial effect on E. coli. The antibacterial effects were attributed to their ability to permeabilize and depolarize the cytoplasmic membrane. Significance and Impact of the Study:  This study showed the potential use of flow cytometry as a suitable method to investigate the mode of antibacterial action of essential oil components.

No abstract

Psoriasis is characterized by a specific microRNA expression profile, distinct from that of healthy skin. MiR-31 is one of the most highly overexpressed microRNAs in psoriasis skin; however, its biological role in the disease has not been studied. In this study, we show that miR-31 is markedly overexpressed in psoriasis keratinocytes. Specific inhibition of miR-31 suppressed NF-κB–driven promoter luciferase activity and the basal and TNF-α–induced production of IL-1β, CXCL1/growth-related oncogene-α, CXCL5/epithelial-derived neutrophil-activating peptide 78, and CXCL8/IL-8 in human primary keratinocytes. Moreover, interference with endogenous miR-31 decreased the ability of keratinocytes to activate endothelial cells and attract leukocytes. By microarray expression profiling, we identified genes regulated by miR-31 in keratinocytes. Among these genes, we identified serine/threonine kinase 40 (STK40), a negative regulator of NF-κB signaling, as a direct target for miR-31. Silencing of STK40 rescued the suppressive effect of miR-31 inhibition on cytokine/chemokine expression, indicating that miR-31 regulates cytokine/chemokine expression via targeting STK40 in keratinocytes. Finally, we demonstrated that TGF-β1, a cytokine highly expressed in psoriasis epidermis, upregulated miR-31 expression in keratinocytes in vitro and in vivo. Collectively, our findings suggest that overexpression of miR-31 contributes to skin inflammation in psoriasis lesions by regulating the production of inflammatory mediators and leukocyte chemotaxis to the skin. Our data indicate that inhibition of miR-31 may be a potential therapeutic option in psoriasis.

MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that play important roles in the regulation of gene expression. We previously identified a characteristic miRNA expression profile in psoriasis, distinct from that of healthy skin. One of the most downregulated miRNAs in psoriasis skin was microRNA-125b (miR-125b). In this study, we aimed to identify the potential role(s) of miR-125b in psoriasis pathogenesis. In situ hybridization results showed that the major cell type responsible for decreased miR-125b levels in psoriasis lesions was the keratinocyte. Overexpression of miR-125b in primary human keratinocytes suppressed proliferation and induced the expression of several known differentiation markers. Conversely, inhibition of endogenous miR-125b promoted cell proliferation and delayed differentiation. Fibroblast growth factor receptor 2 (FGFR2) was identified as one of the direct targets for suppression by miR-125b by luciferase reporter assay. The expression of miR-125b and FGFR2 was inversely correlated in both transfected keratinocytes and in psoriatic skin. Knocking down FGFR2 expression by siRNA suppressed keratinocyte proliferation, but did not enhance differentiation. Altogether, our results demonstrate a role for miR-125b in the regulation of keratinocyte proliferation and differentiation, partially through the regulation of FGFR2. Loss of miR-125b in psoriasis skin may contribute to hyperproliferation and aberrant differentiation of keratinocytes.

Background:The role of microRNAs in cutaneous squamous cell carcinoma (cSCC) is not well understood. Results: cSCC has a unique miRNAome. MicroRNA-125b is down-regulated in human cSCC and suppresses growth and motility of cSCC cells through targeting Matrix Metallopeptidase 13. Conclusion: MicroRNA-125b may play a tumor suppressive role in cSCC. Significance: This study suggests a role for microRNAs in cSCC pathogenesis.

AimsMicroRNAs (miRNAs) play important roles in the pathogenesis of cardiovascular diseases. Circulating miRNAs were recently identified as biomarkers for various physiological and pathological conditions. In this study, we aimed to identify the circulating miRNA fingerprint of vulnerable coronary artery disease (CAD) and explore its potential as a novel biomarker for this disease.Methods and ResultsThe Taqman low-density miRNA array and coexpression network analyses were used to identify distinct miRNA expression profiles in the plasma of patients with typical unstable angina (UA) and angiographically documented CAD (UA group, n = 13) compared to individuals with non-cardiac chest pain (control group, n = 13). Significantly elevated expression levels of miR-106b/25 cluster, miR-17/92a cluster, miR-21/590-5p family, miR-126*, and miR-451 were observed in UA patients compared to controls. These findings were validated by real-time PCR in another 45 UA patients, 31 stable angina patients, and 37 controls. In addition, miR-106b, miR-25, miR-92a, miR-21, miR-590-5p, miR-126* and miR-451 were upregulated in microparticles (MPs) isolated from the plasma of UA patients (n = 5) compared to controls (n = 5). Using flow cytometry and immunolabeling, we further found that Annexin V+ MPs were increased in the plasma samples of UA patients compared to controls, and the majority of the increased MPs in plasma were shown to be Annexin V+ CD31+ MPs. The findings suggest that Annexin V+ CD31+ MPs may contribute to the elevated expression of the selected miRNAs in the circulation of patients with vulnerable CAD.ConclusionThe circulating miRNA signature, consisting of the miR-106b/25 cluster, miR-17/92a cluster, miR-21/590-5p family, miR-126* and miR-451, may be used as a novel biomarker for vulnerable CAD.Trial RegistrationChinese Clinical Trial Register, ChiCTR-OCH-12002349.

:  MicroRNAs are short non‐coding RNAs that regulate gene expression. Previously, in a genome‐wide screen, we found deregulation of microRNA expression in psoriasis skin. MicroRNA‐21 (miR‐21) is one of the microRNAs significantly up‐regulated in psoriasis skin lesions. To identify the cell type responsible for the increased miR‐21 level, we compared expression of miR‐21 in epidermal cells and dermal T cells between psoriasis and healthy skin and found elevated levels of miR‐21 in psoriasis in both cell types. In cultured T cells, expression of miR‐21 increased markedly upon activation. To explore the function of miR‐21 in primary human T helper cells, we inhibited miR‐21 using a tiny seed‐targeting LNA‐anti‐miR. Specific inhibition of miR‐21 increased the apoptosis rate of activated T cells. Our results suggest that miR‐21 suppresses apoptosis in activated T cells, and thus, overexpression of miR‐21 may contribute to T cell–derived psoriatic skin inflammation.