Distinct haplotype structure at the innate immune receptor Toll‐like receptor 2 across bank vole populations and lineages in Europe

Parasite‐mediated selection may contribute to the maintenance of genetic variation at host immune genes over long time scales. To date, the best evidence for the long‐term maintenance of immunogenetic variation in natural populations comes from studies on the major histocompatibility complex (MHC) genes, whereas evidence for such processes from other immune genes remains scarce. In the present study, we show that, despite pronounced population differentiation and the occurrence of numerous private alleles within populations, the innate immune gene Toll‐like receptor 2 (TLR2) displays a distinct haplotype structure in 21 bank vole (Myodes glareolus) populations across Europe. Haplotypes from all populations grouped in four clearly differentiated clusters, with the three main clusters co‐occurring in at least three previously described mitochondrial lineages. This pattern indicates that the distinct TLR2 haplotype structure may precede the split of the mitochondrial lineages 0.19–0.56 Mya and suggests that haplotype clusters at this innate immune receptor are maintained over prolonged time in wild bank vole populations.     

Microbe‐inducible trafficking pathways that control Toll‐like receptor signaling

The receptors of the mammalian innate immune system are designed for rapid microbial detection, and are located in organelles that are conducive to serve these needs. However, emerging evidence indicates that the sites of microbial detection are not the sites of innate immune signal transduction. Rather, microbial detection triggers the movement of receptors to regions of the cell where factors called sorting adaptors detect active receptors and promote downstream inflammatory responses. These findings highlight the critical role that membrane trafficking pathways play in the initiation of innate immunity to infection. In this review, we describe pathways that promote the microbe‐inducible endocytosis of Toll‐like receptors (TLRs), and the microbe‐inducible movement of TLRs between intracellular compartments. We highlight a new class of proteins called Transporters Associated with the eXecution of Inflammation (TAXI), which have the unique ability to transport TLRs and their microbial ligands to signaling‐competent regions of the cell, and we discuss the means by which the subcellular sites of signal transduction are defined.      

Immune complex negatively regulates Toll‐like receptor 9‐mediated immune responses in B cells through the inhibitory Fc‐gamma receptor IIb

Because inappropriate activation of Toll‐like receptor 9 (TLR9) may induce pathological damage, negative regulation of the TLR9‐triggered immune response has attracted considerable attention. Nonpathogenic immune complex (IC) has been demonstrated to have beneficial therapeutic effects in some kinds of autoimmune diseases. However, the role of IC in the regulation of TLR9‐triggered immune responses and the underlying mechanisms remain unclear. In this study, it was demonstrated that IC stimulation of B cells not only suppresses CpG‐oligodeoxynucleotide (CpG‐ODN)‐induced pro‐inflammatory IL‐6 and IgM κ production, but also attenuates CD40 and CD80 expression. Furthermore, our results suggest that the receptor for the Fc portion of IgG (FcγR) IIb is involved in the suppressive effect of IC on TLR9‐mediated CD40, CD80 and IL‐6 expression. Finally, it was found that IC down‐regulates TLR9 expression in CpG‐ODN activated B cells. Our results provide an outline of a new pathway for the negative regulation of TLR9‐triggered immune responses in B cells via FcγRIIb. A new mechanistic explanation of the therapeutic effect of nonpathogenic IC on inflammatory and autoimmune diseases is also provided.     

The Importance of Toll‐like Receptors in NF‐κB Signaling Pathway Activation by Helicobacter pylori Infection and the Regulators of this Response

Helicobacter pylori (H. pylori) is a common pathogenic bacterium in the stomach that infects almost half of the population worldwide and is closely related to gastric diseases and some extragastric diseases, including iron‐deficiency anemia and idiopathic thrombocytopenic purpura. Both the Maastricht IV/Florence consensus report and the Kyoto global consensus report have proposed the eradication of H. pylori to prevent gastric cancer as H.pylori has been shown to be a major cause of gastric carcinogenesis. The interactions between H. pylori and host receptors induce the release of the proinflammatory cytokines by activating proinflammatory signaling pathways such as nuclear factor kappa B (NF‐κB), which plays a central role in inflammation, immune response, and carcinogenesis. Among these receptors, Toll‐like receptors (TLRs) are classical pattern recognition receptors in the recognition of H. pylori and the mediation of the host inflammatory and immune responses to H. pylori. TLR polymorphisms also contribute to the clinical consequences of H. pylori infection. In this review, we focus on the functions of TLRs in the NF‐κB signaling pathway activated by H. pylori, the regulators modulating this response, and the functions of TLR polymorphisms in H.pylori‐related diseases.     

Critical role of Toll‐like receptor 2 in Bacteroides fragilis‐mediated immune responses in murine peritoneal mesothelial cells

In this study, the role of Toll‐like receptor 2 (TLR2) in immune responses of murine peritoneal mesothelial cells against Bacteroides fragilis was investigated. Enzyme linked immunosorbent assay was used to measure cytokines and chemokines. Activation of nuclear factor κB (NF‐κB‐α) and mitogen‐activated protein kinases (MAP kinases) was investigated by western blot analysis. B. fragilis induced production of interleukin‐6, chemokine (C‐X‐C motif) ligand 1 (CXCL1) and chemokine (C‐C motif) ligand 2 (CCL2) in wild type peritoneal mesothelial cells; this was impaired in TLR2‐deficient cells. In addition, in response to B. fragilis, phosphorylation of inhibitory NF‐κB‐α and c‐Jun N‐terminal kinase mitogen‐activated protein kinase (MAPK) was induced in wild type mesothelial cells, but not in TLR2‐deficient cells,. Inhibitor assay revealed that NF‐κB and MAPKs are essential for B. fragilis‐induced production of CXCL1 and CCL2 in mesothelial cells. These findings suggest that TLR2 mediates immune responses in peritoneal mesothelial cells in response to B. fragilis.     

Rictor regulates the vasculogenic mimicry of melanoma via the AKT‐MMP‐2/9 pathway

Vasculogenic mimicry (VM)‐positive melanomas are usually associated with poor prognosis. Rictor, the key component of the rapamycin‐insensitive complex of mTOR (mTORC2), is up‐regulated in several cancers, especially in melanomas with poor prognosis. The aim of this study was to investigate the role of Rictor in the regulation of VM and the mechanism underlying this possible regulation. VM channels were found in 35 of 81 tested melanoma samples and high Rictor expression correlated with VM structures. Moreover, Kaplan–Meier survival curves indicated that VM structures and high Rictor expression correlated with shorter survival in patients with melanoma. In vitro, Rictor knockdown by short hairpin RNA (shRNA) significantly inhibited the ability of A375 and MUM‐2B melanoma cells to form VM structures, as evidenced by most tubes remaining open. Cell cycle analysis revealed that Rictor knockdown blocked cell growth and resulted in the accumulation of cells in G2/M phase, and cell migration and invasion were greatly affected after Rictor down‐regulation. Western blotting assays indicated that down‐regulating Rictor significantly inhibited the phosphorylation of AKT at Ser⁴⁷³ and Thr³⁰⁸, which subsequently inhibited the expression and activity of downstream MMP‐2/9, as confirmed by real‐time PCR and gelatin Zymography. MK‐2206, a small‐molecule inhibitor of AKT, similarly inhibited the activity of AKT and secretion of MMP‐2/9, further supporting that Rictor down‐regulation inhibits the phosphorylation of AKT and activity of downstream MMP‐2/9 to affect VM formation. In conclusion, Rictor plays an important role in melanoma VM via the Rictor—AKT—MMP‐2/9 signalling pathway.     

The long non‐coding RNA PVT1 represses ANGPTL4 transcription through binding with EZH2 in trophoblast cell

Despite progress in diagnostics and treatment for preeclampsia, it remains the foremost cause of maternal and foetal perinatal morbidity and mortality worldwide. Over recent years, various lines of evidence have emphasized long non‐coding RNAs (lncRNAs) which function as an innovative regulator of biological behaviour, as exemplified by proliferation, apoptosis and metastasis. However, the role of lncRNAs has not been well described in preeclampsia. Here, we identified a lncRNA, PVT1, whose expression was down‐regulated in qRT‐PCR analyses in severe preeclampsia. The effects of PVT1 on development were studied after suppression and overexpression of PVT1 in HTR‐8/SVneo and JEG3 cells. PVT1 knockdown notably inhibited cell proliferation and stimulated cell cycle accumulation and apoptosis. Exogenous PVT1 significantly increased cell proliferation. Based on analysis of RNAseq data, we found that PVT1 could affect the expression of numerous genes, and then investigated the function and regulatory mechanism of PVT1 in trophoblast cells. Further mechanistic analyses implied that the action of PVT1 is moderately attributable to its repression of ANGPTL4 via association with the epigenetic repressor Ezh2. Altogether, our study suggests that PVT1 could play an essential role in preeclampsia progression and probably acts as a latent therapeutic marker; thus, it might be a useful prognostic marker when evaluating new therapies for patients with preeclampsia.     

Bax assembles into large ring‐like structures remodeling the mitochondrial outer membrane in apoptosis

The Bcl‐2 family proteins Bax and Bak are essential for the execution of many apoptotic programs. During apoptosis, Bax translocates to the mitochondria and mediates the permeabilization of the outer membrane, thereby facilitating the release of pro‐apoptotic proteins. Yet the mechanistic details of the Bax‐induced membrane permeabilization have so far remained elusive. Here, we demonstrate that activated Bax molecules, besides forming large and compact clusters, also assemble, potentially with other proteins including Bak, into ring‐like structures in the mitochondrial outer membrane. STED nanoscopy indicates that the area enclosed by a Bax ring is devoid of mitochondrial outer membrane proteins such as Tom20, Tom22, and Sam50. This strongly supports the view that the Bax rings surround an opening required for mitochondrial outer membrane permeabilization (MOMP). Even though these Bax assemblies may be necessary for MOMP, we demonstrate that at least in Drp1 knockdown cells, these assemblies are not sufficient for full cytochrome c release. Together, our super‐resolution data provide direct evidence in support of large Bax‐delineated pores in the mitochondrial outer membrane as being crucial for Bax‐mediated MOMP in cells.     

Overexpression of the leucine‐rich receptor‐like kinase gene LRK2 increases drought tolerance and tiller number in rice

Drought represents a key limiting factor of global crop distribution. Receptor‐like kinases play major roles in plant development and defence responses against stresses such as drought. In this study, LRK2, which encodes a leucine‐rich receptor‐like kinase, was cloned and characterized and found to be localized on the plasma membrane in rice. Promoter–GUS analysis revealed strong expression in tiller buds, roots, nodes and anthers. Transgenic plants overexpressing LRK2 exhibited enhanced tolerance to drought stress due to an increased number of lateral roots compared with the wild type at the vegetative stage. Moreover, ectopic expression of LRK2 seedlings resulted in increased tiller development. Yeast two‐hybrid screening and bimolecular fluorescence complementation (BiFC) indicated a possible interaction between LRK2 and elongation factor 1 alpha (OsEF1A) in vitro. These results suggest that LRK2 functions as a positive regulator of the drought stress response and tiller development via increased branch development in rice. These findings will aid our understanding of branch regulation in other grasses and support improvements in rice genetics.     

LncRNA MEG3 inhibits the progression of prostate cancer by modulating miR‐9‐5p/QKI‐5 axis

This study was designed to detecting the influences of lncRNA MEG3 in prostate cancer. Aberrant lncRNAs expression profiles of prostate cancer were screened by microarray analysis. The qRT‐PCR and Western blot were employed to investigating the expression levels of lncRNA MEG3, miR‐9‐5p and QKI‐5. The luciferase reporter assay was utilized to testifying the interactions relationship among these molecules. Applying CCK‐8 assay, wound healing assay, transwell assay and flow cytometry in turn, the cell proliferation, migration and invasion abilities as well as apoptosis were measured respectively. LncRNA MEG3 was a down‐regulated lncRNA in prostate cancer tissues and cells and could inhibit the expression of miR‐9‐5p, whereas miR‐9‐5p down‐regulated QKI‐5 expression. Overexpressed MEG3 and QKI‐5 could decrease the abilities of proliferation, migration and invasion in prostate cancer cells effectively and increased the apoptosis rate. On the contrary, miR‐9‐5p mimics presented an opposite tendency in prostate cancer cells. Furthermore, MEG3 inhibited tumour growth and up‐regulated expression of QKI‐5 in vivo. LncRNA MEG3 was a down‐regulated lncRNA in prostate cancer and impacted the abilities of cell proliferation, migration and invasion, and cell apoptosis rate, this regulation relied on regulating miR‐9‐5p and its targeting gene QKI‐5.     

Early administration of nifedipine protects against angiotensin II‐induced cardiomyocyte hypertrophy through regulating CaMKII–SERCA2a pathway and apoptosis in rat cardiomyocytes

The calcium channel blocker (CCB), nifedipine, is a more effective treatment for early‐ than late‐stage cardiac hypertrophy. We investigated the effects of early‐ and late‐stage nifedipine administration on calcium homeostasis, CaMKII (Ca²⁺/calmodulin‐dependent protein kinase II) activity and apoptosis of cardiomyocytes under hypertrophic stimulation with angiotensin II (AngII). Primary rat cardiomyocytes were divided into five treatment groups: AK, AngII plus the CaMKII inhibitor, KN‐93; AN‐1 (early‐stage), AngII plus nifedipine × 48 h; AN‐2 (late‐stage), AngII × 48 h, then AngII plus nifedipine × 48 h; C, untreated; and A, AngII × 48 h. The t1/2β [time required for intracellular Ca²⁺ concentration ([Ca²⁺]i) to decline to one half of the peak value] decreased; however, CaMKII and SERCA2a (sarcoplasmic reticulum Ca²⁺‐ATPase 2a) activities increased in the AN‐1 group compared with the AK group. In the AN‐2 group compared with the AN‐1 group, CaMKII activity, t1/2α [time required for [Ca²⁺]i to increase from the bottom to one half of peak value], t1/2β, and apoptosis increased. These results indicate that the timing of CCB administration affects the calcium concentration and apoptosis of hypertrophic cardiomyocytes through the CaMKII–SERCA2a signalling pathway, thereby influencing the drug's protective activity against cardiomyocyte hypertrophy. Copyright © 2016 John Wiley & Sons, Ltd.     

MiR‐520b promotes the progression of non‐small cell lung cancer through activating Hedgehog pathway

Although the non‐small cell lung cancer (NSCLC) is one of the most malignant tumours worldwide, the mechanisms controlling NSCLC tumourigenesis remain unclear. Here, we find that the expression of miR‐520b is up‐regulated in NSCLC samples. Further studies have revealed that miR‐520b promotes the proliferation and metastasis of NSCLC cells. In addition, miR‐520b activates Hedgehog (Hh) pathway. Inhibitor of Hh pathway could relieve the oncogenic effect of miR‐520b upon NSCLC cells. Mechanistically, we demonstrate that miR‐520b directly targets SPOP 3′‐UTR and decreases SPOP expression, culminating in GLI2/3 stabilization and Hh pathway hyperactivation. Collectively, our findings unveil that miR‐520b promotes NSCLC tumourigenesis through SPOP‐GLI2/3 axis and provide miR‐520b as a potential diagnostic biomarker and therapeutic target for NSCLC.