The 5-year survival rate for colorectal cancer is approximately 55 % because of its invasion and metastasis. The epithelial–mesenchymal transition (EMT) is one of the well-defined processes during the invasion and distant metastasis of primary epithelial tumors. miR-429, a member of the miR-200 family of microRNAs, was previously shown to inhibit the expression of transcriptional repressors ZEB1/delta EF1 and SIP1/ZEB2, and regulate EMT. In this study, we showed that miR-429 was significantly downregulated in colorectal carcinoma (CRC) tissues and cell lines. We found that miR-429 inhibited the proliferation and growth of CRC cells in vitro and in vivo, suggesting that miR-429 could play a role in CRC tumorigenesis. We also showed that downregulation of miR-429 may contribute to carcinogenesis and the initiation of EMT of CRC by targeting Onecut2. Further researches indicated that miR-429 inhibited the cells migration and invasion and reversed TGF-β-induced EMT changes in SW620 and SW480 cells. miR-429 could reverse the change of EMT-related markers genes induced by TGF-β1, such as E-cadherin, CTNNA1, CTNNB1, TFN, CD44, MMP2, Vimentin, Slug, Snail, and ZEB2 by targeting Onecut2. Taken together, our data showed that transcript factor Onecut2 is involved in the EMT, migration and invasion of CRC cells; miR-429 inhibits the initiation of EMT and regulated expression of EMT-related markers by targeting Onecut2; and miR-429 or Onecut2 is the important therapy target for CRC. Electronic supplementary materialThe online version of this article (doi:10.1007/s11010-013-1950-x) contains supplementary material, which is available to authorized users.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly infectious pathogen that causes severe diseases in pigs and great economic losses to the swine industry worldwide. Type I interferons (IFNs) play a crucial role in antiviral immunity. In the present study, we demonstrated that infection with the highly pathogenic PRRSV strain JXwn06 antagonized type I IFN expression induced by poly(I·C) in both porcine alveolar macrophages (PAMs) and blood monocyte-derived macrophages (BMo). Subsequently, we showed that the inhibition of poly(I·C)-induced IFN-␤ production by PRRSV was dependent on the blocking of NF-B signaling pathways. By screening PRRSV nonstructural and structural proteins, we demonstrated that nonstructural protein 4 (nsp4), a viral 3C-like serine protease, significantly suppressed IFN-␤ expression. Moreover, we verified that nsp4 inhibited NF-B activation induced by signaling molecules, including RIG-I, VISA, TRIF, and IKK␤. nsp4 was shown to target the NF-B essential modulator (NEMO) at the E349-S350 site to mediate its cleavage. Importantly, nsp4 mutants with defective protease activity abolished its ability to cleave NEMO and inhibit IFN-␤ production. These findings might have implications for our understanding of PRRSV pathogenesis and its mechanisms for evading the host immune response. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) is a major agent of respiratory diseases in pigs.Like many other viruses, PRRSV has evolved a variety of strategies to evade host antiviral innate immunity for survival and propagation. In this study, we show that PRRSV nsp4 is a novel antagonist of the NF-B signaling pathway, which is responsible for regulating the expression of type I interferons and other crucial cytokines. We then investigated the underlying mechanism used by nsp4 to suppress NF-B-mediated IFN-␤ production. We found that nsp4 interfered with the NF-B signaling pathway through the cleavage of NEMO (a key regulator of NF-B signaling) at the E349-S350 site, leading to the downregulation of IFN-␤ production induced by poly(I·C). The data presented here may help us to better understand PRRSV pathogenesis.

T cells maintain a quiescent state prior to activation. As inappropriate T cell activation can cause disease, T cell quiescence must be preserved. Despite its importance, the mechanisms underlying the “quiescent state” remain elusive. Here, we identify BTG1 and BTG2 (BTG1/2) as factors responsible for T cell quiescence. BTG1/2-deficient T cells show an increased proliferation and spontaneous activation due to a global increase in messenger RNA (mRNA) abundance, which reduces the threshold to activation. BTG1/2 deficiency leads to an increase in polyadenylate tail length, resulting in a greater mRNA half-life. Thus, BTG1/2 promote the deadenylation and degradation of mRNA to secure T cell quiescence. Our study reveals a key mechanism underlying T cell quiescence and suggests that low mRNA abundance is a crucial feature for maintaining quiescence.

The primary structure of the COOH-terminal region of troponin I (TnI) is highly conserved among the cardiac, slow, and fast skeletal muscle TnI isoforms and across species. Although no binding site for the other thin filament proteins is found at the COOH terminus of TnI, truncations of the last 19-23 amino acid residues reduce the activity of TnI in the inhibition of actomyosin ATPase and result in cardiac muscle malfunction. We have developed a specific monoclonal antibody (mAb), TnI-1, against the conserved COOH terminus of TnI. Using this mAb, isolation of the troponin complex by immunoaffinity chromatography from muscle homogenate and immunofluorescence microscopic staining of myofibrils indicate that the COOH terminus of TnI forms an exposed structure in the muscle thin filament. Binding of this mAb to the COOH terminus of cardiac TnI induced extensive conformational changes in the protein, suggesting an allosteric role of this region in the functional integrity of troponin. In the absence of Ca2+, the binding of troponin C and troponin T to TnI had very little effect on the conformation of the COOH terminus of TnI as indicated by the unaffected mAb affinity for the TnI-1 epitope. However, Ca2+ significantly increased the accessibility of the TnI-1 epitope on TnI in the presence of troponin C and troponin T. The results provide evidence that the COOH terminus is an essential structure in TnI and participates in the allosteric switch during Ca2+ activation of contraction.