Reticulon 3 interacts with NS4B of the hepatitis C virus and negatively regulates viral replication by disrupting NS4B self‐interaction

The non‐structural protein 4B (NS4B) of the hepatitis C virus (HCV) is an endoplasmic reticulum (ER) membrane protein comprising two consecutive amphipathic α‐helical domains (AH1 and AH2). Its self‐oligomerization via the AH2 domain is required for the formation of the membranous web that is necessary for viral replication. Previously, we reported that the host‐encoded ER‐associated reticulon 3 (RTN3) protein is involved in the formation of the replication‐associated membranes of (+)RNA enteroviruses during viral replication. In this study, we demonstrated that the second transmembrane region of RTN3 competed for, and bound to, the AH2 domain of NS4B, thus abolishing NS4B self‐interaction and leading to the downregulation of viral replication. This interaction was mediated by two crucial residues, lysine 52 and tyrosine 63, of AH2, and was regulated by the AH1 domain. The silencing of RTN3 in Huh7 and AVA5 cells harbouring an HCV replicon enhanced the replication of HCV, which was counteracted by the overexpression of recombinant RTN3. The synthesis of viral RNA was also increased in siRNA‐transfected human primary hepatocytes infected with HCV derived from cell culture. Our results demonstrated that RTN3 acted as a restriction factor to limit the replication of HCV.     

In vitro modification of human centromere protein CENP-C fragments by small ubiquitin-like modifier (SUMO) protein: definitive identification of the modification sites by tandem mass spectrometry analysis of the isopeptides

Protein sumoylation by small ubiquitin-like modifier (SUMO) proteins is an important post-translational regulatory modification. A role in the control of chromosome dynamics was first suggested when SUMO was identified as high-copy suppressor of the centromere protein CENP-C mutants. CENP-C itself contains a consensus sumoylation sequence motif that partially overlaps with its DNA binding and centromere localization domain. To ascertain whether CENP-C can be sumoylated, tandem mass spectrometry (MS) based strategy was developed for high sensitivity identification and sequencing of sumoylated isopeptides present among in-gel-digested tryptic peptides of SDS-PAGE fractionated target proteins. Without a predisposition to searching for the expected isopeptides based on calculated molecular mass and relying instead on the characteristic MS/MS fragmentation pattern to identify sumolylation, we demonstrate that several other lysine residues located not within the perfect consensus sumoylation motif psiKXE/D, where psi represents a large hydrophobic amino acid, and X represents any amino acid, can be sumolylated with a reconstituted in vitro system containing only the SUMO proteins, E1-activating enzyme and E2-conjugating enzyme (Ubc9). In all cases, target sites that can be sumoylated by SUMO-2 were shown to be equally susceptible to SUMO-1 attachments which include specific sites on SUMO-2 itself, Ubc9, and the recombinant CENP-C fragments. Two non-consensus sites on one of the CENP-C fragments were found to be sumoylated in addition to the predicted site on the other fragment. The developed methodologies should facilitate future studies in delineating the dynamics and substrate specificities of SUMO-1/2/3 modifications and the respective roles of E3 ligases in the process.     

Dynein is required for polarized dendritic transport and uniform microtubule orientation in axons

Axons and dendrites differ in both microtubule organization and in the organelles and proteins they contain. Here we show that the microtubule motor dynein has a crucial role in polarized transport and in controlling the orientation of axonal microtubules in Drosophila melanogaster dendritic arborization (da) neurons. Changes in organelle distribution within the dendritic arbors of dynein mutant neurons correlate with a proximal shift in dendritic branch position. Dynein is also necessary for the dendrite-specific localization of Golgi outposts and the ion channel Pickpocket. Axonal microtubules are normally oriented uniformly plus-end-distal; however, without dynein, axons contain both plus- and minus-end distal microtubules. These data suggest that dynein is required for the distinguishing properties of the axon and dendrites: without dynein, dendritic organelles and proteins enter the axon and the axonal microtubules are no longer uniform in polarity.     

Optical polarization properties of the diffraction spectra from single fibers of skeletal muscle.

The diffraction spectra of laser light from single fibers of skeletal muscle exhibit a large degree of optical depolarization. When the linearly polarized incident laser source is oriented at polarization angles between 0 less than theta less than pi/2 rad with respect to the fiber axis, the diffracted light is elliptically polarized. These results show that the phase angle of the ellipse rotates by as much as 20 degrees when the fiber is stretched from 2.4 to 3.8 microns. To further ascertain that the observed phenomenon is diffraction related, an experiment monitoring the spectra of scattered light in between diffraction orders showed this signal to be significantly more linearly polarized. These results suggest that the degree of elliptical polarization of the diffraction spectra is a sensitive probe of A-band dynamics, including changes of the anisotropic S-2 elements.     

Kinetics of T helper subsets and associated cytokines correlate well with the clinical activity of graft-versus-host disease

Background

CD4⁺interferon (IFN)-γ⁺ T cell (Th1) and CD4⁺interleukin (IL)-4⁺ T cell (Th2) polarizations are crucial in the pathogenesis of graft-versus-host disease (GVHD). However, this hypothesis is largely based on animal experiments of Parent-into-F1 GVHD model. The causal relationship between kinetics of Th1, Th2 and associated cytokines and the clinical activity of GVHD in a real world situation remains unknown.

Methodology

Peripheral blood was collected every week prospectively from Day 0 to Day 210 (patients without GVHD) or Day 300 (patients with chronic GVHD) after allogeneic peripheral blood stem cell transplantation in consecutive 27 patients. The frequencies of Th1 and Th2 within CD4⁺ T cells were determined by flow cytometry and pplasma IFN-γ, IL-12, IL-4, and IL-10 were determined by ELISA.

Principal Findings

Kinetics of Th1, Th2 frequency, and the plasma IL-10 and IFN-γ more commonly coincided with, rather than predicted, the activity of GVHD. These markers are significantly higher when acute or chronic GVHD developed. The kinetics of IL-10 is especially correlated well with the activity of GVHD during clinical course of immunosuppressive treatment. For patients with hepatic GVHD, there is a positive correlation between plasma IL-10 levels and the severity of hepatic injury. The frequency of Th2 is also significant higher in acute GVHD and tends to be higher in chronic GVHD. Interestingly, there is a very good positive correlation between the frequency of Th1 and Th2 (r = 0.951, p<0.001). The plasma level of IL-4 and IL-12 are not associated with the activity of GVHD.

Conclusions

The frequency of Th1, Th2 within CD4⁺ T cells and plasma IL-10 and IFN-γ are good biomarkers of GVHD. Plasma IL-10 can also be used to monitor the therapeutic responsiveness. Furthermore, both Th1 and Th2 likely contribute to the pathogenesis of GVHD.     

The indispensable role of CCR5 for in vivo suppressor function of tumor-derived CD103+ effector/memory regulatory T cells

CD103 is a marker for identification of effector/memory regulatory T cells (Tregs). CD103(+) Tregs are potent suppressors of tissue inflammation in several infectious diseases, autoimmune diseases, and cancers. However, the underlying mechanisms for this potent suppression ability remain unclear. The current study was designed to clarify this issue. Unexpectedly, we found both CD103(+) and CD103(-) Tregs had similar suppression capacity in vitro. We then chose a murine tumor model for investigation of the in vivo behavior of these Tregs. The suppression ability in vivo against the anti-tumor ability of CD8(+) T cells was restricted to CD103(+) Tregs although both Tregs had equal in vitro suppression ability. In addition, CD103(+) Tregs expressed significantly higher levels of CCR5 than those of CD103(-) Tregs and accumulated more in tumors than did CD103(-) Tregs. Furthermore, blockade of CCR5 signaling, either by CCR5(-/-)CD103(+) Tregs or by CCL5 knockdown tumor, could reduce the migration of CD103(+) Tregs into tumors and impair their in vivo suppression ability. In conclusion, these results indicate that the potent in vivo suppression ability of CD103(+) Tregs is due to the tissue-migration ability through CCR5 expression.     

Hyperthyroidism and Risk for Bipolar Disorders: A Nationwide Population-Based Study

Background

Thyroid disorders have long been associated with psychiatric illness, often with symptoms suggestive of mood disorders. The most common clinical features associated with hyperthyroidism are anxiety and depression. The risk of bipolar disorders, especially bipolar mania, among patients with thyroid disorders has not been well characterized.

Objective

We explored the relationship of hyperthyroidism and the subsequent development of bipolar disorders, and examined the risk factors for bipolar disorders in patients with hyperthyroidism.

Methods

We identified patients who were diagnosed with hyperthyroidism between 2000 and 2010 in the Taiwan National Health Insurance Research Database. A comparison cohort without hyperthyroidism was matched based on age, sex, and comorbidities. The occurrence of bipolar disorders was evaluated in both cohorts based on diagnosis and the use of mood stabilizer drugs.

Results

The hyperthyroidism cohort consisted of 21, 574 patients, and the comparison cohort consisted of 21, 574 matched control patients without hyperthyroidism. The incidence of bipolar disorders (incidence rate ratio [IRR], 2.31, 95% CI 1.80–2.99, P<.001) was higher for the hyperthyroidism patients than the control patients. Multivariate, matched regression models showed that women (HR 2.02, 95% CI 1.34–3.05, P = .001), patients with alcohol use disorders (HR 3.03, 95% CI 1.58–5.79, P = .001), and those with asthma (HR 1.70, 95% CI 1.18–2.43, P = .004) were independent risk factors for the development of bipolar disorders in hyperthyroidism patients.

Conclusions

Although a possibility that the diagnosis of bipolar disorders in this study actually includes "bipolar disorders due to hyperthyroidism" cannot be excluded, this study suggests that hyperthyroidism may increase the risk of developing bipolar disorders.