Abnormally High Levels of Virus-Infected IFN-γ+CCR4+CD4+CD25+ T Cells in a Retrovirus-Associated Neuroinflammatory Disorder

Background

Human T-lymphotropic virus type 1 (HTLV-1) is a human retrovirus associated with both HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which is a chronic neuroinflammatory disease, and adult T-cell leukemia (ATL). The pathogenesis of HAM/TSP is known to be as follows: HTLV-1-infected T cells trigger a hyperimmune response leading to neuroinflammation. However, the HTLV-1-infected T cell subset that plays a major role in the accelerated immune response has not yet been identified.

Principal Findings

Here, we demonstrate that CD4⁺CD25⁺CCR4⁺ T cells are the predominant viral reservoir, and their levels are increased in HAM/TSP patients. While CCR4 is known to be selectively expressed on T helper type 2 (Th2), Th17, and regulatory T (Treg) cells in healthy individuals, we demonstrate that IFN-γ production is extraordinarily increased and IL-4, IL-10, IL-17, and Foxp3 expression is decreased in the CD4⁺CD25⁺CCR4⁺ T cells of HAM/TSP patients as compared to those in healthy individuals, and the alteration in function is specific to this cell subtype. Notably, the frequency of IFN-γ-producing CD4⁺CD25⁺CCR4⁺Foxp3⁻ T cells is dramatically increased in HAM/TSP patients, and this was found to be correlated with disease activity and severity.

Conclusions

We have defined a unique T cell subset—IFN-γ⁺CCR4⁺CD4⁺CD25⁺ T cells—that is abnormally increased and functionally altered in this retrovirus-associated inflammatory disorder of the central nervous system.     

A periplasmic,pyridoxal-5′-phosphate-dependent amino acid racemase in <Emphasis Type="Italic">Pseudomonas taetrolens</Emphasis>

The pyridoxal-5′-phosphate (PLP)-dependent amino acid racemases occur in almost every bacterium but may differ considerably with respect to substrate specificity. We here isolated the cloned broad substrate specificity racemase ArgR of Pseudomonas taetrolens from Escherichia coli by classical procedures. The racemase was biochemically characterized and amongst other aspects it was confirmed that it is mostly active with lysine, arginine and ornithine, but merely weakly active with alanine, whereas the alanine racemase of the same organism studied in comparison acts on alanine only. Unexpectedly, sequencing the amino-terminal end of ArgR revealed processing of the protein, with a signal peptide cleaved off. Subsequent localization studies demonstrated that in both P. taetrolens and E. coli ArgR activity was almost exclusively present in the periplasm, a feature so far unknown for any amino acid racemase. An ArgR-derivative carrying a carboxy-terminal His-tag was made and this was demonstrated to localize even in an E. coli mutant devoid of the twin-arginine translocation (Tat) pathway in the periplasm. These data indicate that ArgR is synthesized as a prepeptide and translocated in a Tat-independent manner. We therefore propose that ArgR translocation depends on the Sec system and a post-translocational insertion of PLP occurs. As further experiments showed, ArgR is necessary for the catabolism of d-arginine and d-lysine by P. taetrolens.     

Identification and characterization of quantitative trait loci for root elongation by using introgression lines with genetic background of Indica-type rice variety IR64

The root is the sole organ taking up water and nutrients from soils. Hence, root system architecture (RSA) is important for enhancing high-level and stable rice (Oryza sativa L.) production. However, the genetic improvement of RSA has received less attention than yield and yield components. Here, we aimed to identify and characterize quantitative trait loci (QTLs) for RSA by determining the maximum root length (MRL) of seedlings grown hydroponically under various concentrations of NH₄ ⁺. We used a total of 280 introgression lines (ILs) with an Indica-type variety IR64 genetic background, consisting of ten sibling ILs groups, to detect the QTLs. Greater variation of MRL was found in three sibling ILs groups. In total, five QTLs were detected by single marker analyses: two each on chromosomes 5 and 6 and one on chromosome 7. Among them, the most effective QTL was detected on a segment derived from IR69093-41-2-3-2 (YP5), which was localized to the long-arm of chromosome 6. The QTL, designated as qRL6.4-YP5, concerned in root elongation. MRL and total root length of a near-isogenic line (NIL) for qRL6.4-YP5 were significantly (15.2–24.6 %) higher than those of IR64 over a wide range of NH₄ ⁺ concentrations. Root number and weight of the NIL were the same as those of IR64. These results indicated that qRL6.4-YP5 was a constitutive QTL for root length in response to change in nitrogen concentrations. To enhance yield potential by improving RSA, qRL6.4-YP5 might help to improve root development in rice molecular breeding programs with marker-assisted selection.     

Comparison of plasma membrane proteomic changes of Arabidopsis suspension-cultured cells (T87 Line) after cold and ABA treatment in association with freezing tolerance development

The plasma membrane (PM) is the primary site of freezing injury in plants. To determine global changes in PM protein profiles in association with freezing tolerance development, proteome analysis of the purified PM of Arabidopsis suspension-cultured cells (T87 line) was conducted with label-free protein quantification technology. Freezing tolerance of Arabidopsis cells at the lag growth phase (8 d old) increased after cold acclimation (CA) or ABA treatment. Proteome analysis assigned 658 proteins in the PM in total, of which 45.3% (298 proteins) were predicted to have transmembrane domains. They were classified into several functional categories, with the primary categories being proteins in transporters, signal transduction, protein destination and storage, and cell structure. After CA, 271 proteins increased and 111 proteins decreased. ABA treatment resulted in 185 increased and 56 decreased proteins. Of these, 139 increased and 49 decreased proteins were identified in common after both CA and ABA treatment. In addition, there were proteins specifically expressed in cold- (132 increased and 62 decreased) or ABA- (46 increased and 7 decreased) treated cells. Collectively, our results clearly show that (i) responses of the PM proteome to CA and ABA treatment overlap substantially but, at the same time, some proteins exhibited different response patterns in each treatment; and (ii) the majority of ABA-responsive proteins are CA-responsive proteins but not vice versa, suggesting complex interactions of CA and ABA signaling pathways in the PM proteome responses.     

Conserved Role of unc-79 in Ethanol Responses in Lightweight Mutant Mice

The mechanisms by which ethanol and inhaled anesthetics influence the nervous system are poorly understood. Here we describe the positional cloning and characterization of a new mouse mutation isolated in an N-ethyl-N-nitrosourea (ENU) forward mutagenesis screen for animals with enhanced locomotor activity. This allele, Lightweight (Lwt), disrupts the homolog of the Caenorhabditis elegans (C. elegans) unc-79 gene. While Lwt/Lwt homozygotes are perinatal lethal, Lightweight heterozygotes are dramatically hypersensitive to acute ethanol exposure. Experiments in C. elegans demonstrate a conserved hypersensitivity to ethanol in unc-79 mutants and extend this observation to the related unc-80 mutant and nca-1;nca-2 double mutants. Lightweight heterozygotes also exhibit an altered response to the anesthetic isoflurane, reminiscent of unc-79 invertebrate mutant phenotypes. Consistent with our initial mapping results, Lightweight heterozygotes are mildly hyperactive when exposed to a novel environment and are smaller than wild-type animals. In addition, Lightweight heterozygotes exhibit increased food consumption yet have a leaner body composition. Interestingly, Lightweight heterozygotes voluntarily consume more ethanol than wild-type littermates. The acute hypersensitivity to and increased voluntary consumption of ethanol observed in Lightweight heterozygous mice in combination with the observed hypersensitivity to ethanol in C. elegans unc-79, unc-80, and nca-1;nca-2 double mutants suggests a novel conserved pathway that might influence alcohol-related behaviors in humans.     

NIRF/UHRF2 occupies a central position in the cell cycle network and allows coupling with the epigenetic landscape

As predicted by systems biology, a paradigm shift will emerge through the integration of information about different layers of cellular processes. The cell cycle network is at the heart of the cellular computing system, and orchestrates versatile cellular functions. The NIRF/UHRF2 ubiquitin ligase is an "intermodular hub" that occupies a central position in the network, and facilitates coordination among the cell cycle machinery, the ubiquitin-proteasome system, and the epigenetic system. NIRF interacts with cyclins, CDKs, p53, pRB, PCNA, HDAC1, DNMTs, G9a, methylated histone H3 lysine 9, and methylated DNA. NIRF ubiquitinates cyclins D1 and E1, and induces G1 arrest. The NIRF gene is frequently lost in tumors and is a candidate tumor suppressor, while its paralog, the UHRF1 gene, is hardly altered. Thus, investigations of NIRF are essential to understand the entire biological systems. Through integration of the enormous information flows, NIRF may contribute to the coupling between the cell cycle network and the epigenetic landscape. We propose the new paradigm that NIRF produces the extreme diversity in the network wiring that helps the diversity of Waddington's canals.     

The dynactin complex maintains the integrity of metaphasic centrosomes to ensure transition to anaphase

The dynactin complex is required for activation of the dynein motor complex, which plays a critical role in various cell functions including mitosis. During metaphase, the dynein-dynactin complex removes spindle checkpoint proteins from kinetochores to facilitate the transition to anaphase. Three components (p150(Glued), dynamitin, and p24) compose a key portion of the dynactin complex, termed the projecting arm. To investigate the roles of the dynactin complex in mitosis, we used RNA interference to down-regulate p24 and p150(Glued) in human cells. In response to p24 down-regulation, we observed cells with delayed metaphase in which chromosomes frequently align abnormally to resemble a "figure eight," resulting in cell death. We attribute the figure eight chromosome alignment to impaired metaphasic centrosomes that lack spindle tension. Like p24, RNA interference of p150(Glued) also induces prometaphase and metaphase delays; however, most of these cells eventually enter anaphase and complete mitosis. Our findings suggest that although both p24 and p150(Glued) components of the dynactin complex contribute to mitotic progression, p24 also appears to play a role in metaphase centrosome integrity, helping to ensure the transition to anaphase.