Double‐stranded
RNA
interference (ds
RNA
i) represents a primary means of anti‐viral defense in plants, worms, and insects, yet appears mostly supplanted by the protein‐based interferon (
IFN
) ...response in vertebrates such as mammals. The degree to which ds
RNA
i is anti‐viral in mammals has been contentious. Maillard
et al
(
) find that ds
RNA
i retains sequence‐specific silencing in mammalian cells incapable of triggering an
IFN
response, suggesting that ds
RNA
i is inhibited by the action of interferon‐stimulated genes. Importantly, they observe that while ds
RNA
can “vaccinate” against the incoming cognate virus though ds
RNA
i silencing, no ds
RNA
i is observed with viral infection alone, suggesting that this evolutionarily conserved anti‐viral pathway is present but functionally elusive in the cell types studied thus far.
PNPLA3 I148M genetic variant increases the risk of NAFLD development and progression. To explore the underlying mechanism, we developed a hPSC-derived liver culture to study NAFLD by utilizing ...disease risk factors derived from patients. In liver cultures containing the variant, we observed that I148M variant increased the risk of NAFLD by elevating IL6/STAT3 signaling, which agreed with analysis of patient liver biopsies. Our findings demonstrate a potential causal link between elevated IL6/STAT3 activity and I148M variant-mediated risk of NALFD. Further, our liver culture is a useful platform for exploring genetic variants in NAFLD development.
Similar to other hepatotropic viruses, hepatitis E virus (HEV) has been notoriously difficult to propagate in cell culture, limiting studies to unravel its biology. Recently, major advances have been ...made by passaging primary HEV isolates and selecting variants that replicate efficiently in carcinoma cells. These adaptations, however, can alter HEV biology. We have explored human embryonic or induced pluripotent stem cell (hESC/iPSC)-derived hepatocyte-like cells (HLCs) as an alternative to conventional hepatoma and hepatocyte cell culture systems for HEV studies. HLCs are permissive for nonadapted HEV isolate genotypes (gt)1-4 replication and can be readily genetically manipulated. HLCs, therefore, enable studies of pan-genotype HEV biology and will serve as a platform for testing anti-HEV treatments. Finally, we discuss how hepatocyte polarity is likely an important factor in the maturation and spread of infectious HEV particles.
The molecular mechanism of the hepatic tropism of hepatitis C virus (HCV) remains incompletely defined. In vitro hepatic differentiation of pluripotent stem cells produces hepatocyte-like cells ...(HLCs) permissive for HCV infection, providing an opportunity for studying liver development and host determinants of HCV susceptibility. We previously identified the transition stage of HCV permissiveness and now investigate whether a host protein whose expression is induced during this transition stage is important for HCV infection. We suppressed the expression of a liver-specific protein, cell death-inducing DFFA-like effector b (CIDEB), and performed hepatocyte function and HCV infection assays. We also used a variety of cell-based assays to dissect the specific step of the HCV life cycle that potentially requires CIDEB function. We found CIDEB to be an essential cofactor for HCV entry into hepatocytes. Genetic interference with CIDEB in stem cells followed by hepatic differentiation leads to HLCs that are refractory to HCV infection, and infection time course experiments revealed that CIDEB functions in a late step of HCV entry, possibly to facilitate membrane fusion. The role of CIDEB in mediating HCV entry is distinct from those of the well-established receptors, as it is not required for HCV pseudoparticle entry. Finally, HCV infection effectively downregulates CIDEB protein through a posttranscriptional mechanism.
This study identifies a hepatitis C virus (HCV) entry cofactor that is required for HCV infection of hepatocytes and potentially facilitates membrane fusion between viral and host membranes. CIDEB and its interaction with HCV may open up new avenues of investigation of lipid droplets and viral entry.
Erythroblastic island (EBI), composed of a central macrophage and surrounding erythroid cells, is the first hematopoietic niche discovered for erythropoiesis. Yet, the identity of the central ...macrophage has so far remained elusive. Based on the previous findings that F4/80, VCAM1 and CD169 are potential mouse central macrophage markers, we first calculated the number of F4/80+VCAM1+CD169+ mouse macrophages in the mouse bone marrow and compared it to the number of Ter119+ erythroblasts. We found that the ratio of F4/80+VCAM1+CD169+ macrophage and erythroblasts is about 1:2. Given the fact that one central macrophage is surrounded by multiple erythroblasts, the above finding suggests that it is unlikely that all the F4/80+VCAM1+CD169+ macrophages are central macrophages.
Erythropoietin (Epo) is essential for erythropoiesis. It has been reported that the Epo receptor (Epor) is expressed in peritoneal macrophages. These findings promoted us to speculate that EBI central macrophages may express Epor so that Epo acts on both erythroid cells and the central macrophages simultaneously in the niche to ensure efficient and optimal red cell production. To test this notion, we first examined whether mouse bone marrow and fetal liver macrophages express Epor using the Epor-GFPcre knockin mouse model. We found that ~5% of bone marrow F4/80+ macrophages and ~35% of fetal liver F4/80+ macrophages express Epor-GFP. As negative control, no Epor-GFP macrophages are noted in wild type F4/80+ macrophages. Importantly, ImageStream analyses revealed the native EBIs in bone marrow and fetal liver are formed by Epor+ but not Epor- macrophages. Bioinformatics analyses of RNA-seq data on the sorted Epor+ and Epor- macrophage populations revealed that molecules involved in central macrophage-erythroblast association such as VCAM1, CD169, and molecules known to be important for central macrophage function such as Dnase2a, ferroportin, are highly expressed in Epor+ macrophages. In marked contrast, highly expressed pathways in Epor- macrophages are associated with immune responses including antigen process and presentation. Intriguingly, the immune related pathways are dramatically downregulated in the Epor+ macrophages, suggesting that the Epor+ macrophages in bone marrow and fetal liver have evolved a specialized function in supporting erythropoiesis.
To examine whether expression of Epor in EBI central macrophages is a conserved feature across species, we generated Epor-GFPcre knockin rat using the CRISP/Cas9 technology. Using CD163 as rat macrophage marker, we found that a subpopulation of rat bone marrow CD163+ macrophages expresses Epor-GFP. As a negative control, no Epor-GFP macrophages are noted in wild type CD163+ macrophages. To examine whether EPOR is expressed in human EBI central macrophages, antibody specificity for human EPOR is critical. To this end, we employed CRISP/Cas9 approach to knock out EPOR in K562 and Hela cell lines and validated the specificity of a commercially available anti-human EPOR antibody. Using CD163, CD169 as human macrophage markers, we found that EPOR is also expressed in a subpopulation of human macrophages. Moreover, in vitro EBI formation assay revealed that human EPOR+ but not EPOR- macrophages form EBIs with erythroid cells and that the EBI formation is enhanced by EPO.
In summary, we for the first time, after discovery of the EBIs 60 years ago, have identified Epor+ macrophages in mouse bone marrow and fetal liver as EBI central macrophages. Our findings provide solid foundation for studying the mechanisms by which erythropoieis is supported EBI central macrophages. A better understanding of such mechanisms will provide extensive new knowledge on basic biology of erythropoiesis. It is also important to understand the pathology of erythropoietic disorders as well as to improve ex vivo erythrocyte production.
No relevant conflicts of interest to declare.
To study the effect of β 2 on energy performance and unsteady characteristics of the single-channel pump, the experimental tests about the energy characteristics, head pulsation, pressure fluctuation ...and radial force have been conducted by the synchronous test. 3 different impellers with the blade outlet angle β 2 of 8°, 16° and 25° respectively are studied. The results show that with the increase of β 2 from 8° to 25°, the head increases gradually and the maximum increase amplitude reaches 22.6 %. As β 2 changes from 8° to 25°, there is a maximum efficiency. The mixing loss at the impeller outlet can be decreased by reducing β 2 . With the increasing of β 2 , the minimum head in time domain gradually lag and the maximum head gradually advances. The pressure fluctuation in each measuring point shows the trend of increasing first and then decreasing with the increasing of the flow rate. With β 2 increasing, the radial force also increases and the maximum increase amplitude of minimum radial force is larger than 8 %. The research can provide some reference for the optimization of single channel pumps.
To establish a method for sensitive and rapid determination of pentachlorophenol (PCP) in different water.
Based on the actual national standard detection method of PCP, gas chromatographic ...conditions and quantitative method were modified and optimized. The modified method was used for the determination of pentachlorophenol in samples from natural water, output water and tap water.
A modified method for the detection of PCP in drinking water samples was developed with the conditions of gas chromatography as follows: the capillary column was used for separation and tribromophenol (TBP) as internal standard for quantification, the linear range were 0.1 - 10 microg/L, and the correlation coefficient was 0.9999. The limit of detection was 4.5 ng/L. Recoveries were between 90.1% and 98.4%, and RSD was less than 4.1% .
The proposed method is a sensitive and accurate method for trace analysis of PCP in different water.
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