Background:The molecular mechanism underlying the regulation of cellulase production by T. reesei is unclear. Results: The absence of sugar transporter Stp1 enhanced cellulase gene induction whereas the absence of Crt1 abolished cellulase gene expression. Conclusion: Crt1 is essential in cellulase gene induction independent of intracellular sugar delivery. Significance: These data shed light on the mechanism by which T. reesei senses and transmits cellulose signal.

Appropriate perception of cellulose outside the cell by transforming it into an intracellular signal ensures the rapid production of cellulases by cellulolytic Hypocrea jecorina. The major extracellular ␤-glucosidase BglI (CEL3a) has been shown to contribute to the efficient induction of cellulase genes. Multiple ␤-glucosidases belonging to glycosyl hydrolase (GH) family 3 and 1, however, exist in H. jecorina. Here we demonstrated that CEL1b, like CEL1a, was an intracellular ␤-glucosidase displaying in vitro transglycosylation activity. We then found evidence that these two major intracellular ␤-glucosidases were involved in the rapid induction of cellulase genes by insoluble cellulose. Deletion of cel1a and cel1b significantly compromised the efficient gene expression of the major cellulase gene, cbh1. Simultaneous absence of BglI, CEL1a, and CEL1b caused the induction of the cellulase gene by cellulose to further deteriorate. The induction defect, however, was not observed with cellobiose. The absence of the three ␤-glucosidases, rather, facilitated the induced synthesis of cellulase on cellobiose. Furthermore, addition of cellobiose restored the productive induction on cellulose in the deletion strains. The results indicate that the three ␤-glucosidases may not participate in transforming cellobiose beyond hydrolysis to provoke cellulase formation in H. jecorina. They may otherwise contribute to the accumulation of cellobiose from cellulose as inducing signals.

Th17 cells and interleukin‐17 (IL‐17) have been found to play an important role in the pathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Response to IL‐17, reactive astrocytes accompany with immune cells infiltration and axonal damage in MS/EAE. However, the role and the regulatory mechanism of IL‐17‐activated astrocytes in inflammation and in the EAE process still remain largely unknown. Here, we elucidated that miR‐409‐3p and miR‐1896, as co‐upregulated microRNAs in activated astrocytes and in EAE mice, targeted suppressor of cytokine signaling proteins 3 (SOCS3). Overexpression of miR‐409‐3p or miR‐1896 significantly reduced SOCS3 expression and increased phosphorylation of STAT3 as well as induced the inflammatory cytokines production (IL‐1β, IL‐6, IP‐10, MCP‐1, and KC), CD4+T cells migration and demyelination, in turn aggravating EAE development. Importantly, the effects of co‐overexpression of miR‐409‐3p and miR‐1896 in vitro or in vivo are strongly co‐operative. In contrast, simultaneously silenced miR‐409‐3p and miR‐1896 co‐operatively ameliorates inflammation and demyelination in the central nervous system of EAE mice. Collectively, our findings highlight that miR‐409‐3p and miR‐1896 co‐ordinately promote the production of inflammatory cytokines in reactive astrocytes through the SOCS3/STAT3 pathway and enhance reactive astrocyte‐directed chemotaxis of CD4+T cells, leading to aggravate pathogenesis in EAE mice. Co‐inhibition of miR‐409‐3p and miR‐1896 may be a therapeutic target for treating MS and neuroinflammation.

bLactose (1,4-O-␤-D-galacto-pyranosyl-D-glucose) induces cellulolytic enzymes in Trichoderma reesei and is in fact one of the most important soluble carbon sources used to produce cellulases on an industrial level. The mechanism underlying the induction is, however, not fully understood. In this study, we investigated the cellular functions of the intracellular ␤-glucosidases CEL1a and CEL1b in the induction of cellulase genes by lactose in T. reesei. We demonstrated that while CEL1a and CEL1b were functionally equivalent in mediating the induction, the simultaneous absence of these intracellular ␤-glucosidases abolished cbh1 gene expression on lactose. D-Galactose restored the efficient cellulase gene induction in the ⌬cel1a strain independently of its reductive metabolism, but not in the ⌬cel1a ⌬cel1b strain. A further comparison of the transcriptional responses of the ⌬cel1a ⌬cel1b strain complemented with wild-type CEL1a or a catalytically inactive CEL1a version and the ⌬cel1a strain constitutively expressing CEL1a or the Kluyveromyces lactis ␤-galactosidase LAC4 showed that both the CEL1a protein and its glycoside hydrolytic activity were indispensable for cellulase induction by lactose. We also present evidence that intracellular ␤-glucosidase-mediated lactose induction is further conveyed to XYR1 to ensure the efficiently induced expression of cellulase genes.C ost-effective conversion of plant cell wall-derived polysaccharides holds the potential for production of an environmentally clean and renewable source of energy and platform chemicals (1). Trichoderma reesei (teleomorph Hypocrea jecorina) is well known for its high capacity to secrete large amounts of lignocellulosic enzymes that release fermentable sugars and has thus been developed into one of the most prolific industrial cellulase producers. High-yield production of the bulk of the plant cell walldegrading machinery in T. reesei is, however, dependent on induction by insoluble substrates that include cellulose, hemicellulose, and mixtures of plant polymers. Considering the ease of manipulation and the complication of separating enzymes from insoluble plant cell wall materials, soluble inducing substrates are usually preferred or required (2). Among others, the disaccharide lactose (1,4-O-␤-D-galacto-pyranosyl-D-glucose) is an important and economic soluble carbon source for cellulase production by T. reesei. However, the induced cellulase yields on lactose are usually lower than those on cellulose (3, 4). Understanding the differences in the inducing efficiency and the mode by which lactose triggers cellulase formation would be helpful for improving the performance of industrial strains.In fungi, catabolism of lactose is thought to proceed either by extracellular hydrolysis and subsequent uptake of the resulting sugar monomers or by uptake of the disaccharide followed by intracellular hydrolysis (4). For T. reesei, it has been assumed that lactose metabolism relies on the first strategy, based on several findings, including the absence of appar...

Probiotics might offer an attractive alternative to prevent and control Clostridium difficile (C. difficile) infection (CDI). Limited information is available on the ability of commercially used bifidobacterial strains to inhibit C. difficile. This study examined the anti-clostridial effects of Bifidobacterium longum JDM301, a widely used commercial probiotic strain in China, in vitro and in vivo. In vitro evaluation revealed a significant reduction in C. difficile counts when JDM301 was co-cultured with C. difficile, which was correlated with the significant decrease in clostridial toxin titres (TcdA and TcdB). Furthermore, the cell-free culture supernatants (CFS) of JDM301 inhibited C. difficile growth and degraded TcdA and TcdB. Notably, the results showed that acid pH promoted the degradation of TcdA by CFS from JDM301. Furthermore, comparative studies among 10 B. longum strains were performed, which showed that the inhibitory effect of CFS from JDM301 was similar with the other 8 B. longum strains and higher than strain BLY1. However, when it was neutralized, the significant different was lost. When present together, it was suggested that the acid pH induced by probiotics not only played important roles in the growth inhibition against C. difficile resulting in the reduction of toxins titres, but also directly promoted the degradation of clostridial toxin. In vivo studies proved that JDM301 partially relieved damage to tissues caused by C. difficile and also decreased the number of C. difficile and toxin levels. In summary, our results demonstrated that the commercial strain, JDM301 could be considered a probiotic able to exert anti-toxin capability and most of the CFS from Bifidobacterium were able to inhibit the growth of C. difficile, depending on acid pH. These results highlighted a potential that JDM301 could be helpful in preventing CDI and that most of the bifidobacterial strains could (at least partially) exert protective effects by reducing toxin titres through growth inhibition against toxigenic C. difficile.

Our current understanding of the host-microbiota interaction in the gut is dominated by studies focused primarily on prokaryotic bacterial communities. However, there is an underappreciated symbiotic eukaryotic protistic community that is an integral part of mammalian microbiota. How commensal protozoan bacteria might interact to form a stable microbial community remains poorly understood. Here, we describe a murine protistic commensal, phylogenetically assigned as Tritrichomonas musculis, whose colonization in the gut resulted in a reduction of gut bacterial abundance and diversity in wild-type C57BL/6 mice. Meanwhile, dietary nutrient and commensal bacteria also influenced the protozoan’s intestinal colonization and stability. While mice fed a normal chow diet had abundant T. musculis organisms, switching to a Western-type high-fat diet led to the diminishment of the protozoan from the gut. Supplementation of inulin as a dietary fiber to the high-fat diet partially restored the protozoan’s colonization. In addition, a cocktail of broad-spectrum antibiotics rendered permissive engraftment of T. musculis even under a high-fat, low-fiber diet. Furthermore, oral administration of Bifidobacterium spp. together with dietary supplementation of inulin in the high-fat diet impacted the protozoan’s intestinal engraftment in a bifidobacterial species-dependent manner. Overall, our study described an example of dietary-nutrient-dependent murine commensal protozoan-bacterium cross talk as an important modulator of the host intestinal microbiome. IMPORTANCE Like commensal bacteria, commensal protozoa are an integral part of the vertebrate intestinal microbiome. How protozoa integrate into a commensal bacterium-enriched ecosystem remains poorly studied. Here, using the murine commensal Tritrichomonas musculis as a proof of concept, we studied potential factors involved in shaping the intestinal protozoal-bacterial community. Understanding the rules by which microbes form a multispecies community is crucial to prevent or correct microbial community dysfunctions in order to promote the host’s health or to treat diseases.

BackgroundInterleukin-7 receptor (IL-7R) is involved in the abnormal function of solid tumors, but the role and regulatory mechanisms of IL-7R in HBV-related hepatocellular carcinoma (HCC) are still unclear.MethodsGene and protein expression levels of IL-7R were examined in hepatoma cells transfected with hepatitis B virus (HBV) plasmids and in hepatoma cells transfected with the multifunctional nonstructural protein X (HBX). The expression of HBX and IL-7R was measured by immunohistochemical analysis in HBV-related HCC tissues. The role of NF-κB and Notch1 pathways in HBX-mediated expression of IL-7R in hepatoma cells was examined. Activation of IL-7R downstream of intracellular signaling proteins AKT, JNK, STAT5, and the associated molecules CyclinD1 and matrix metalloproteinase-9 (MMP)-9, was assessed in HBX-positive cells with or without treatment with IL-7R short hairpin RNA (shRNA). Additionally, the role of IL-7R in HBX-mediated proliferation and migration of hepatoma cells was investigated.ResultsThe expression of IL-7R was increased in hepatoma cells transfected with HBV plasmids; HBX was responsible for the HBV-mediated upregulation of IL-7R. Compared to adjacent tissues, the expression of HBX and IL-7R was increased in HBV-related HCC tissues. Additionally, the relative expression levels of HBX were associated with IL-7R in HBV-related HCC tissues. The activation of NF-κB pathways and expression of Notch1 were increased in hepatoma cells transfected with HBX, and inhibition of NF-κB and Notch1 pathways significantly decreased HBX-mediated expression of IL-7R. The activation of AKT and JNK and the expression of CyclinD1 and MMP-9 were increased in HBX-positive cells. When cells were treated with IL-7R shRNA, the activation of AKT and JNK, as well as the expression of CyclinD1 and MMP-9, were significantly inhibited. Additionally, IL-7R was responsible for HBX-induced proliferation and migration ability of hepatoma cells.ConclusionsOur data demonstrate that HBX can upregulate IL-7R via NF-κB and Notch1 pathways to facilitate the activation of intracellular pathways and expression of associated molecules, and contribute to proliferation and migration of hepatoma cells.

LIM and SH3 domain protein 1 (LASP-1) is known to participate in the progression of hepatocellular carcinoma (HCC). We previously showed that ectopic expression of hepatitis B virus (HBV) X protein (HBX) enhanced the expression of LASP-1, which promoted proliferation and migration of HCC cells. Here, we further demonstrated the molecular mechanism underlying upregulation of LASP-1, mediated by HBX, in HBV-infected HCC cells. Through a luciferase activity assay, we discovered that the LASP-1 promoter region regulated by HBX contained an AP-1 binding element in human hepatoma cells. Interestingly, c-Jun, one subunit of AP-1, was mainly responsible for activation, mediated by HBX, of the LASP-1 promoter. Furthermore, HBX was shown not only to interact with phosphorylated c-Jun in HCC cells but also to activate c-Jun by increasing the activation of PI3-K/JNK signaling. Chromatin immunoprecipitation (ChIP) assay demonstrated that HBX was capable of binding to the LASP-1 promoter with c-Jun. Further, the expression levels of HBX were shown to be significantly positively correlated with that of LASP-1 and phosphorylatedc-Jun in HBV-related HCC tissues by immunohistochemistry analysis. In addition, the N-terminus of HBX was found to be responsible for the activation of c-Jun, as well as the expression of LASP-1. Taken together, these results suggest that HBX contributes to LASP-1 expression via the activation of c-Jun to increase the promoter activity of LASP-1 in HBV-related HCC cells.