Characterization of the TMV replicase proteins: localization and interactions with Rab GDI proteins

Tobacco mosaic virus (TMV) is a model positive-strand RNA virus. TMV encodes two replicase proteins, both of which contain methyltransferase and helicase domains; the 183 kDa protein contains an additional RNA-dependent RNA polymerase domain. Using this virus, virus-host interactions important in the initial establishment of infection and formation of replicase complexes were investigated. Specifically, on the virus side, replicase proteins were examined for regions that may contribute to its localization to the endoplasmic reticulum (ER) during TMV infection. An ER localization domain was identified in a region between amino acids 599 and 701. Alanine substitutions were introduced into this region and examined for their effects on the virus. Several possible hypotheses are discussed as to how this domain may function during infection. Concerning the host, an interaction with a host protein, a Rab GDP Dissociation Inhibitor (Rab GDI), was examined. This interaction occurred with tomato and tobacco Rab GDIs as well as with the originally identified Arabidopsis thaliana Rab GDI (AtGDI2). Silencing of Rab GDI transcripts enhanced the number of infection sites in TMV:GFP-infected plants, but did not alter viral movement or overall accumulation, indicating a possible role in initial establishment of infection. Rab GDI-silenced Nicotiana benthamiana plants showed cellular morphologies similar to those of TMV-infected cells. Moreover, TMV infection results in Rab GDI proteins localizing to structures associated with viral replication. Taken together these data indicate a role for Rab GDI proteins in the initial establishment of infection. Two models of how Rab GDI proteins may contribute to TMV infection are discussed. These studies examine parts of the viral life cycle that are not very well understood, in particular the initiation and establishment of infection. Although vesicle trafficking has been shown to be important for several different pathogens, this is the first time that a Rab GDI protein has been identified as participating in viral replication. Understanding initiation of infection and susceptibility of a host to a pathogen are vital to elucidating pathogen-host interactions and developing disease resistance strategies

Association of the Tobacco mosaic virus 126kDa replication protein with a GDI protein affects host susceptibility

AbstractAn interaction between the Tobacco mosaic virus (TMV) 126kDa replication protein and a host-encoded Rab GDP dissociation inhibitor (GDI2) was identified and investigated for its role in infection. GDI proteins are essential components of vesicle trafficking pathways. TMV infection alters the localization of GDI2 from the cytoplasm to ER-associated complexes. Partial silencing of GDI2 results in significant increases in the number of TMV infection foci observed in inoculated tissues. However, GDI2 silencing does not affect TMV accumulation at the infection site, cell-to-cell movement, or susceptibility of the host to mechanical inoculation. Furthermore, increases in the number of successful infection foci were specific to TMV and correlated with the appearance of vesicle-like rearrangements in the vacuolar membrane. Tissue infiltrations with brefeldin A, an inhibitor of vesicle trafficking, also enhanced host susceptibility to TMV. Combined these findings suggest that the 126kDa–GDI2 interaction alters vesicle trafficking to enhance the establishment of an infection

Protein Phosphatase 1 (PP1) Is a Post-Translational Regulator of the Mammalian Circadian Clock

Circadian clocks coordinate the timing of important biological processes. Interconnected transcriptional and post-translational feedback loops based on a set of clock genes generate and maintain these rhythms with a period of about 24 hours. Many clock proteins undergo circadian cycles of post-translational modifications. Among these modifications, protein phosphorylation plays an important role in regulating activity, stability and intracellular localization of clock components. Several protein kinases were characterized as regulators of the circadian clock. However, the function of protein phosphatases, which balance phosphorylation events, in the mammalian clock mechanism is less well understood. Here, we identify protein phosphatase 1 (PP1) as regulator of period and light-induced resetting of the mammalian circadian clock. Down-regulation of PP1 activity in cells by RNA interference and in vivo by expression of a specific inhibitor in the brain of mice tended to lengthen circadian period. Moreover, reduction of PP1 activity in the brain altered light-mediated clock resetting behavior in mice, enhancing the phase shifts in either direction. At the molecular level, diminished PP1 activity increased nuclear accumulation of the clock component PER2 in neurons. Hence, PP1, may reduce PER2 phosphorylation thereby influencing nuclear localization of this protein. This may at least partially influence period and phase shifting properties of the mammalian circadian clock

Disease activity and patient-reported outcomes in patients with rheumatoid arthritis and Sjogren\u27s syndrome enrolled in a large observational US registry

The objective of this study was to compare rheumatoid arthritis (RA) disease activity and patient-reported outcomes (PROs) in a national sample of patients with RA with/without Sjogren\u27s syndrome (SS). Adults with RA from a large observational US registry (Corrona RA) with known SS status between 22 April 2010 and 31 July 2018 and a visit 12 (+/- 3) months after index date were identified (n = 36,256/52,757). SS status: determined from a yes/no variable reported at enrolment into the Corrona RA registry and follow-up visits. Index date: date that SS status was recorded (yes/no). Patients received biologic or targeted synthetic disease-modifying antirheumatic drugs as part of standard care. Patients with RA only were followed for \u3e /= 12 months to confirm the absence of SS. Patients were frequency- and propensity-score matched (PSM) 1:1 and stratified by disease duration and treatment response-associated variables, respectively. Clinical Disease Activity Index (CDAI) and PROs 12 months after index visit were compared in patients with and without SS. Baseline characteristics in 283 pairs of PSM patients were balanced. Mean change in CDAI score was numerically lower in patients with RA and SS than patients with RA only (8.8 vs 9.3). Reductions in PROs of pain, fatigue and stiffness were two- to threefold lower for patients with RA and SS versus RA only. Reductions in RA disease activity and RA-related PROs were lower in patients with RA and SS versus those with RA only. Our data indicate that SS adds to treatment challenges; physicians may wish to consider SS status when managing patients with RA

Prevalence of Sjogren\u27s syndrome associated with rheumatoid arthritis in the USA: an observational study from the Corrona registry

The objectives of this analysis were to assess the prevalence of Sjogren\u27s syndrome (SS) associated with rheumatoid arthritis (RA) and to compare baseline characteristics of patients with RA with and without SS. Adult patients with RA from a large observational US registry (Corrona RA), with \u3e /= 1 visit for assessment of SS status between 22 April 2010 and 28 February 2018, were considered. Patients with RA with versus without SS were compared. SS status was determined from a yes/no variable and reported at enrollment into the Corrona RA registry and follow-up visits. Outcomes were unadjusted prevalence of SS in patients with RA, prevalence of SS by RA disease duration, and baseline characteristics in patients with RA by SS status. Of 24,528 eligible patients, 7870 (32.1%) had a diagnosis of RA and SS. The unadjusted overall rate for SS prevalence in patients with RA was 0.30 (95% confidence interval 0.29, 0.31). SS prevalence increased with increasing RA duration. Patients with RA with versus without SS were more likely to be older, female, and seropositive; had a longer RA duration; higher disease activity; and a higher incidence of comorbidities (hypertension, cardiovascular disease, malignancies, and serious infections), erosive disease, and subcutaneous nodules at index date. Patients with RA and SS had a higher disease burden than those with RA only. The prevalence of SS increased as duration of RA increased. RA with SS was associated with seropositivity, more severe RA, extra-articular manifestations, and comorbidities.Key Points* The overall prevalence of SS among patients with RA was 30%.* The prevalence of SS increased with increasing RA disease duration.* Identifying specific clinical characteristics of patients with RA with SS, such as a greater incidence of extra-articular manifestations and comorbidities, may help clinicians to better characterize this patient population

Protein phosphatase 4 controls circadian clock dynamics by modulating CLOCK/BMAL1 activity

In all organisms with circadian clocks, post-translational modifications of clock proteins control the dynamics of circadian rhythms, with phosphorylation playing a dominant role. All major clock proteins are highly phosphorylated, and many kinases have been described to be responsible. In contrast, it is largely unclear whether and to what extent their counterparts, the phosphatases, play an equally crucial role. To investigate this, we performed a systematic RNAi screen in human cells and identified protein phosphatase 4 (PPP4) with its regulatory subunit PPP4R2 as critical components of the circadian system in both mammals an

In vivo characterization of connective tissue remodeling using infrared photoacoustic spectra

Premature cervical remodeling is a critical precursor of spontaneous preterm birth, and the remodeling process is characterized by an increase in tissue hydration. Nevertheless, current clinical measurements of cervical remodeling are subjective and detect only late events, such as cervical effacement and dilation. Here, we present a photoacoustic endoscope that can quantify tissue hydration by measuring near-infrared cervical spectra. We quantify the water contents of tissue-mimicking hydrogel phantoms as an analog of cervical connective tissue. Applying this method to pregnant women in vivo, we observed an increase in the water content of the cervix throughout pregnancy. The application of this technique in maternal healthcare may advance our understanding of cervical remodeling and provide a sensitive method for predicting preterm birth

Características clínicas y demográficas de sujetos con patologías reumáticas ingresados a rehabilitación: estudio descriptivo retrospectivo

Antecedentes: Las enfermedades reumáticas (ER) son afecciones que comprometen al sistema musculoesquelético y existen más de 100 tipos. Los autores de este estudio no encontramos antecedentes que describan características de los sujetos con ER admitidos en un servicio de rehabilitación en Argentina. Objetivo: Describir y analizar una muestra de sujetos con ER ingresados en el Servicio de Kinesiología del Instituto de Rehabilitación Psicofísica (I.Re.P.) de la Ciudad Autónoma de Buenos Aires entre enero de 2010 y diciembre de 2015.