No abstract

Recent reports suggested that phosphatase of regenerating liver (PRL)-3 might be involved in colorectal carcinoma metastasis with an unknown mechanism.Here we demonstrated that PRL-3 expression was upregulated in human liver carcinoma compared with normal liver. PRL-3 was also highly expressed in metastatic melanoma B16-BL6 cells but not in its lowly metastatic parental cell line, B16 cells. B16 cells transfected with PRL-3 cDNA displayed morphological transformation from epithelial-like shape to fibroblast-like shape. PRL-3-overexpressed cells showed much higher migratory ability, which could be reversed by specific anti-sense oligodeoxynucleotide and the phosphatase inhibitors sodium orthovanadate or potassium bisperoxo oxovanadate V. Meanwhile, the expression of the catalytically inactive PRL-3 mutations (D72A or C104S) significantly reduced the cell migratory capability. In addition, PRL-3 transfectants demonstrated altered extracellular matrix adhesive property and up-regulated integrin-mediated cell spreading efficiency. Furthermore, we confirmed that PRL-3 could facilitate lung and liver metastasis of B16 cells in an experimental metastasis model in mice, consistent with accelerated proliferation and growth rate both in vitro and in vivo. Together, these observations provide convincing evidence that PRL-3 truly plays a causal role in tumor metastasis. Metastasis is the leading cause of death in cancer patients and involves a complex, multistep process including detachment of tumor cells from a primary cancer, invasion of surrounding tissue, entry into the circulatory system, reinvasion, and proliferation at a distant secondary site. 1,2 A wide variety of stimuli have been associated with the spread of tumor cells, including cytokines, hormones, growth factors, cell adhesion molecules, and extracellular components. Many of these stimuli transmit signals via a tyrosyl phosphorylation pathways that dictate whether a tumor cell will grow and divide, change shape, migrate, differentiate, or die. Protein tyrosine phosphorylation is a major posttranslational modification that cells use to regulate signal transduction. The homeostasis of tyrosine phosphorylation is controlled by protein tyrosine kinases (PTKases) that catalyze tyrosine phosphorylation, and protein tyrosine phosphatase (PTPases) that are responsible for dephosphorylation. PTKases, PTPases, and their corresponding substrates are integrated into elaborate signaltransducing networks. Deregulation of phosphorylation is known to result in neoplastic or nonneoplastic disease. 4Phosphatases are as important as the well-studied PTKases because phosphorylation is a dynamic and reversible process. 5 The PTPase superfamily can be divided into three major classes: tyrosine-specific and low-molecular weight phosphatases, which strictly dephosphorylate phosphotyrosine residues, and dual-specific phosphatases, which use protein substrates that contain phosphotyrosine, phosphoserine, and phosphothreonine. Tyrosine-specific PTPases can be further divided into two ...

Tracking how individual naive T cells from a natural TCR repertoire clonally expand, differentiate, and make lineage choices in response to an infection has not previously been possible. Here, using single-cell sequencing technology to identify clones by their unique TCR sequences, we were able to trace the clonal expansion, differentiation trajectory, and lineage commitment of individual virus-specific CD4 T cells during an acute lymphocytic choriomeningitis virus (LCMV) infection. Notably, we found previously unappreciated clonal diversity and cellular heterogeneity among virus-specific helper T cells. Interestingly, although most naive CD4 T cells gave rise to multiple lineages at the clonal level, ∼28% of naive cells exhibited a preferred lineage choice toward either Th1 or TFH cells. Mechanistically, we found that TCR structure, in particular the CDR3 motif of the TCR α chain, skewed lineage decisions toward the TFH cell fate.

No abstract

Avian influenza virus A of the novel H7N9 reassortant subtype was recently found to cause severe human respiratory infections in China. Live poultry markets were suspected locations of the human H7N9 infection sources, based on the cases' exposure histories and sequence similarities between viral isolates. To explore the role of live poultry markets in the origin of the novel H7N9 virus, we systematically examined poultry and environmental specimens from local markets and farms in Hangzhou, using realtime reverse transcription-PCR (RT-PCR) as well as high-throughput next-generation sequencing (NGS). RT-PCR identified specimens positive for the H7 and N9 genomic segments in all of the 12 poultry markets epidemiologically linked to 10 human H7N9 cases. Chickens, ducks, and environmental specimens from the markets contained heavily mixed subtypes, including H7, N9, H9, and N2 and sometimes H5 and N1. The idea of the coexistence of H7N9 and H9N2 subtypes in chickens was further supported by metagenomic sequencing. In contrast, human H7N9 infection cases (n ‫؍‬ 31) were all negative for H9N2 virus according to real-time RT-PCR. The six internal segments were indistinguishable for the H7N9 and H9N2 viruses. The H9, N2, and internal-segment sequences were very close to the sequence of the H9N2 virus circulating in chickens in China recently. Our results provide direct evidence that H9N2 strains coexisted with the novel human-pathogenic H7N9 influenza virus in epidemiologically linked live poultry markets. Avian influenza A virus of the H9N2 subtype likely made a recent contribution to the evolution of the H7N9 virus and continues to do so. IMPORTANCEOur results suggest that avian influenza A virus of the H9N2 subtype likely made a recent contribution to the evolution of the H7N9 virus, a novel reassortant avian influenza virus A subtype, and continues to do so. The finding helps shed light on how the H7N9 virus emerged, spread, and transmitted to humans. It is of considerable interest for assessing the risk of the possible emergence of novel reassortant viruses with enhanced transmissibility to humans.