Establishment of closed 35S ribosomal RNA gene chromatin in stationary Saccharomyces cerevisiae cells.

As a first step in eukaryotic ribosome biogenesis RNA polymerase (Pol) I synthesizes a large ribosomal RNA (rRNA) precursor from multicopy rRNA gene loci. This process is essential for cellular growth and regulated in response to the cell's physiological state. rRNA gene transcription is downregulated upon growth to stationary phase in the yeast Saccharomyces cerevisiae. This reduction correlates with characteristic changes in rRNA gene chromatin structure from a transcriptionally active 'open' state to a non-transcribed 'closed' state. The conserved lysine deacetylase Rpd3 was shown to be required for this chromatin transition. We found that Rpd3 is needed for tight repression of Pol I transcription upon growth to stationary phase as a prerequisite for the establishment of the closed chromatin state. We provide evidence that Rpd3 regulates Pol I transcription by adjusting cellular levels of the Pol I preinitiation complex component core factor (CF). Importantly, our study identifies CF as the complex limiting the number of open rRNA genes in exponentially growing and stationary cells.

Development of an Orthotopic HPV16-Dependent Base of Tongue Tumor Model in MHC-Humanized Mice.

Head and neck squamous cell carcinomas (HNSCC) caused by infections with high-risk human papillomaviruses (HPV) are responsible for an increasing number of head and neck cancers, particularly in the oropharynx. Despite the significant biological differences between HPV-driven and HPV-negative HNSCC, treatment strategies are similar and not HPV targeted. HPV-driven HNSCC are known to be more sensitive to treatment, particularly to radiotherapy, which is at least partially due to HPV-induced immunogenicity. The development of novel therapeutic strategies that are specific for HPV-driven cancers requires tumor models that reflect as closely as possible the characteristics and complexity of human tumors and their response to treatment. Current HPV-positive cancer models lack one or more hallmarks of their human counterpart. This study presents the development of a new HPV16 oncoprotein-dependent tumor model in MHC-humanized mice, modeling the major biologic features of HPV-driven tumors and presenting HLA-A2-restricted HPV16 epitopes. Furthermore, this model was developed to be orthotopic (base of tongue). Thus, it also reflects the correct tumor microenvironment of HPV-driven HNSCC. The cancer cells are implanted in a manner that allows the exact control of the anatomical location of the developing tumor, thereby homogenizing tumor growth. In conclusion, the new model is suited to study HPV16-specific therapeutic vaccinations and other immunotherapies, as well as tumor-targeted interventions, such as surgery or radiotherapy, or a combination of all these modalities.

A trypanosome-derived immunotherapeutics platform elicits potent high-affinity antibodies, negating the effects of the synthetic opioid fentanyl.

Poorly immunogenic small molecules pose challenges for the production of clinically efficacious vaccines and antibodies. To address this, we generate an immunization platform derived from the immunogenic surface coat of the African trypanosome. Through sortase-based conjugation of the target molecules to the variant surface glycoprotein (VSG) of the trypanosome surface coat, we develop VSG-immunogen array by sortase tagging (VAST). VAST elicits antigen-specific memory B cells and antibodies in a murine model after deploying the poorly immunogenic molecule fentanyl as a proof of concept. We also develop a single-cell RNA sequencing (RNA-seq)-based computational method that synergizes with VAST to specifically identify memory B cell-encoded antibodies. All computationally selected antibodies bind to fentanyl with picomolar affinity. Moreover, these antibodies protect mice from fentanyl effects after passive immunization, demonstrating the ability of these two coupled technologies to elicit therapeutic antibodies to challenging immunogens.

Establishment and Maintenance of Open Ribosomal RNA Gene Chromatin States in Eukaryotes.

In growing eukaryotic cells, nuclear ribosomal (r)RNA synthesis by RNA polymerase (RNAP) I accounts for the vast majority of cellular transcription. This high output is achieved by the presence of multiple copies of rRNA genes in eukaryotic genomes transcribed at a high rate. In contrast to most of the other transcribed genomic loci, actively transcribed rRNA genes are largely devoid of nucleosomes adapting a characteristic "open" chromatin state, whereas a significant fraction of rRNA genes resides in a transcriptionally inactive nucleosomal "closed" chromatin state. Here, we review our current knowledge about the nature of open rRNA gene chromatin and discuss how this state may be established.

Certolizumab pegol treatment in axial spondyloarthritis mitigates fat lesion development: 4-year post-hoc MRI results from a phase 3 study.

OBJECTIVES: Fat lesions (FLs) on MRI T1 sequences are considered to be early indicators of structural spinal progression in axial spondyloarthritis (axSpA) patients. In this post-hoc analysis from RAPID-axSpA, we assess whether tumour necrosis factor inhibitor (TNFi) treatment over 4 years impacts FLs in spinal vertebral edges (VEs) of patients with axSpA. METHODS: In RAPID-axSpA (NCT01087762), a 4-year, phase 3 randomized trial, participants were randomized to certolizumab pegol (CZP; 400 mg loading dose at Weeks 0/2/4 then 200/400 mg every 2/4 weeks) or placebo (PBO) at baseline; PBO-randomized participants switched to CZP at Week 16/24 (denoted PBO-randomized/CZP). Spinal MRI scans were taken at Weeks 0, 12, 48, 96 and 204. Changes in proportions of VEs with FLs are reported as odds ratios (ORs) between time points. RESULTS: Overall, 136 participants (CZP: 89, PBO-randomized/CZP: 47) had a baseline and ≥1 post-baseline MRI. The OR (95% confidence interval) vs baseline of FLs was higher in PBO-randomized/CZP vs CZP-randomized participants at Weeks 48 [3.35 (2.16-5.19) vs 1.45 (1.07-1.97)], 96 [2.62 (1.77-3.88) vs 1.84 (1.36-2.48)] and 204 [2.55 (1.59-4.06) vs 1.71 (1.23-2.37)]. Across 204 weeks, FLs increased more in VEs with baseline inflammation [Week 204 OR: 4.84 (2.56-9.18)] than those without [OR: 1.15 (0.78-1.71)]. VEs in which inflammation was resolved by Week 12 had lower FL prevalence at Weeks 48, 96 and 204 compared with VEs with unresolved inflammation. CONCLUSIONS: Early and sustained suppression of inflammation mitigates the risk of long-term FL development in the spine in study participants with axSpA evaluated over 4 years. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT01087762.

Therapeutic vaccination using minimal HPV16 epitopes in a novel MHC-humanized murine HPV tumor model.

Therapeutic vaccination as a treatment option for HPV-induced cancers is actively pursued because the two HPV proteins E6 and E7 represent ideal targets for immunotherapy, as they are non-self and expressed in all tumor stages. MHC-humanized mice are valuable tools for the study of therapeutic cancer vaccines - given the availability of a suitable tumor model. Here, we present for the first time an HPV16 tumor model suitable for fully MHC-humanized A2.DR1 mice, PAP-A2 cells, which in contrast to existing HPV16 tumor models allows the exclusive study of HLA-A2- and DR1-mediated immune responses, without any interfering murine MHC-presented epitopes. We used several HPV16 epitopes that were shown to be presented on human cervical cancer cells by mass spectrometry for therapeutic anti-tumor vaccination in the new tumor model. All epitopes were immunogenic when rendered amphiphilic by incorporation into a molecule containing stearic acids. Prophylactic and therapeutic vaccination experiments with the epitope E7/11-19 demonstrated that effective immune responses could be induced with these vaccination approaches in A2.DR1 mice. Interestingly, the combination of E7/11-19 with other immunogenic HPV16 E6/E7 epitopes caused a reduction of vaccine efficacy, although all tested combinations resulted in a survival benefit. In summary, we present the first HPV16 tumor model for exclusive studies of HLA-A2-mediated anti-HPV tumor immune responses and show anti-tumor efficacy of minimal epitope vaccines.

Accuracy of 64-multidetector computed tomography coronary angiography in patients with symptomatic atrial fibrillation prior to pulmonary vein isolation.

AIMS: Aim of our study was to investigate the value of multidetector computed tomography (MDCT) for detecting significant stenoses of coronary arteries in patients with symptomatic atrial fibrillation (AF) prior to pulmonary vein (PV) ablation (PVA). BACKGROUND: Many patients undergoing PVA for AF receive three-dimensional computed tomography or magnetic resonance tomography imaging for improving anatomical orientation. METHODS: One-hundred and eighty-one patients with AF refractory to antiarrhythmic treatment underwent ECG-gated 64-MDCT for identification of PV anatomy and simultaneous assessment of coronary vessels before PVA. No additional radiation was incurred for MDCT coronary angiography during MDCT scan. Pretest probability for obstructive coronary artery disease (CAD) was estimated. Invasive coronary angiography (ICA) was performed in all patients with at least intermediate risk of CAD. RESULTS: Eighty-six out of 181 patients (48%) had ICA and MDCT, 95 patients (52%) underwent MDCT alone. ICA revealed significant stenoses in 9% of the catheterized patients (8/86). MDCT investigation lead to a sensitivity of 90% (9/10), specificity of 98% (829/844 lesions), positive predictive value (PPV) of 39% (9/24), and negative predictive value (NPV) of 100% (829/830 lesions) for the detection of >50% stenoses seen on ICA. All patients with a significant stenosis were classified as patients with CAD. Overall prevalence of significant CAD detected by MDCT was found to be low with 10% of patients and 2% of all segments. CONCLUSION: MDCT coronary angiography is sensitive and highly specific in patients presenting for PVA. In this group a negative scan reliably excludes significant CAD. These data suggest that MDCT coronary angiography can replace ICA prior to PVA.

Phosphorylation of human cardiac troponin I G203S and K206Q linked to familial hypertrophic cardiomyopathy affects actomyosin interaction in different ways.

cAMP-dependent protein kinase (PKA)-dependent phosphorylation of the two serine residues in the amino terminal region unique to cardiac troponin I (cTnI) is known to cause two effects: (i) decrease of the maximum Ca2+-controlled thin filament-activated myosin S1-ATPase (actoS1-ATPase) activity and mean sliding velocity of reconstituted thin filaments; (ii) rightward shift of the Ca2+ activation curves of actoS1-ATPase activity, filament sliding velocity, and force generation. We have studied the influence of phosphorylation of human wild-type cTnI and of two mutant cTnI (G203S and K206Q) causing familial hypertrophic cardiomyopathy (fHCM) on the secondary structure by circular dichroism spectroscopy and on the Ca2+ regulation of actin-myosin interaction using actoS1-ATPase activity and in vitro motility assays. Both mutations slightly influence the backbone structure of cTnI but only the secondary structure of cTnI-G203S is also affected by bis-phosphorylation of cTnI. In functional studies, cTnI-G203S behaves similarly to wild-type cTnI, i.e. the mutation itself has no measurable effect and bis-phosphorylation alters the actoS1-ATPase activity and the in vitro thin filament motility in the same way as does bis-phosphorylation of wild-type cTnI. In contrast, the mutation K206Q leads to a considerable increase in the maximum actoS1-ATPase activity as well as filament motility compared to wild-type cTnI. Bis-phosphorylation of this mutant cTnI still suppresses the maximum actoS1-ATPase activity and filament sliding velocity but does no longer affect the Ca2+ sensitivity of these processes. Thus, these two fHCM-linked cTnI mutations, although reflecting similar pathological situations, exert different effects on the actomyosin system per se and in response to bis-phosphorylation of cTnI.