Impaired function of rDNA transcription initiation machinery leads to derepression of ribosomal genes with insertions of R2 retrotransposon.

Eukaryotic genomes harbor hundreds of rRNA genes, many of which are transcriptionally silent. However, little is known about selective regulation of individual rDNA units. In Drosophila melanogaster, some rDNA repeats contain insertions of the R2 retrotransposon, which is capable to be transcribed only as part of pre-rRNA molecules. rDNA units with R2 insertions are usually inactivated, although R2 expression may be beneficial in cells with decreased rDNA copy number. Here we found that R2-inserted rDNA units are enriched with HP1a and H3K9me3 repressive mark, whereas disruption of the heterochromatin components slightly affects their silencing in ovarian germ cells. Surprisingly, we observed a dramatic upregulation of R2-inserted rRNA genes in ovaries lacking Udd (Under-developed) or other subunits (TAF1b and TAF1c-like) of the SL1-like complex, which is homologues to mammalian Selective factor 1 (SL1) involved in rDNA transcription initiation. Derepression of rRNA genes with R2 insertions was accompanied by a reduction of H3K9me3 and HP1a enrichment. We suggest that the impairment of the SL1-like complex affects a mechanism of selective activation of intact rDNA units which competes with heterochromatin formation. We also propose that R2 derepression may serve as an adaptive response to compromised rRNA synthesis.

Mechanical Tensions Regulate Gene Expression in the Xenopus laevis Axial Tissues.

During gastrulation and neurulation, the chordamesoderm and overlying neuroectoderm of vertebrate embryos converge under the control of a specific genetic programme to the dorsal midline, simultaneously extending along it. However, whether mechanical tensions resulting from these morphogenetic movements play a role in long-range feedback signaling that in turn regulates gene expression in the chordamesoderm and neuroectoderm is unclear. In the present work, by using a model of artificially stretched explants of Xenopus midgastrula embryos and full-transcriptome sequencing, we identified genes with altered expression in response to external mechanical stretching. Importantly, mechanically activated genes appeared to be expressed during normal development in the trunk, i.e., in the stretched region only. By contrast, genes inhibited by mechanical stretching were normally expressed in the anterior neuroectoderm, where mechanical stress is low. These results indicate that mechanical tensions may play the role of a long-range signaling factor that regulates patterning of the embryo, serving as a link coupling morphogenesis and cell differentiation.

Biomarker assessment in chronic rhinitis and chronic rhinosinusitis: Endothelin-1, TARC/CCL17, neopterin, and α-defensins.

BACKGROUND: Chronic rhinitis (CR) is characteristically divided into several major clinical phenotypes: allergic rhinitis (AR); nonallergic, noninfectious rhinopathy (NAR); and chronic rhinosinusitis (CRS). CRS has two phenotypic variants: CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). An area of growing interest is to identify biologic markers that could assess different aspects of CR phenotypes. OBJECTIVE: The aim of the study was to evaluate four CR biomarkers: endothelin-1 (ET-1), thymus and activation-regulated chemokine (CCL17), neopterin, and α-defensins in subjects with AR, NAR, and CRS. METHODS: Fifty-one patients with AR, 43 patients with NAR, 46 patients with CRSsNP, 54 patients with CRSwNP, and 40 healthy controls were included. ET-1, TARC/CCL17, neopterin, and α-defensins levels in subjects' serum and nasal secretions (NS) were measured by the enzyme-linked immunosorbent assay. RESULTS: High NS levels of ET-1, TARC/CCL17, and α-defensins were characteristic for CRSwNP, although only high NS levels of neopterin were found in the CRSsNP phenotype. AR phenotype was characterized by high NS levels of ET-1 and TARC/CCL17. In the subjects with NAR, none of these biomarker levels in serum and NS differed from those of healthy controls. CONCLUSIONS: CR can be categorized by ET-1, TARC/CCL17, neopterin, and α-defensins into several disease phenotypes. Further studies are needed to better investigate pathophysiologic roles of these biomarkers in CRS.

Expression of TLR2 and TLR4 on peripheral blood monocytes during exacerbation of atopic dermatitis.

BACKGROUND: In atopic dermatitis (AD), monocytes, which accumulate in the inflamed skin, are characterized by a significantly impaired Toll-like receptors (TLR) expression and TLR2-mediated cytokine secretion. However, data on expression of TLR on monocytes of peripheral blood (PB) in AD are not available. OBJECTIVE: To investigate TLR2 and TLR4 expression on PB monocytes during AD exacerbation and to assess the relationships between TLR expressions with AD clinical severity and with serum interleukin (IL) 4, IL-10, and IL-17a levels. METHODS: The objective Scoring Atopic Dermatitis index, TLR2 and TLR4 expression on CD14(+) human leukocyte antigen-DR (HLA-DR(+)) PB monocytes by flow cytometry, serum IL-4, IL-10, IL-17a (enzyme-linked immunosorbent assay) and total immunoglobulin E levels were measured at study entry and after 4 months in patients with AD and healthy controls. RESULTS: Eighty-two patients with AD, 35 women (45.1%) and 47 men (54.9%), mean (standard deviation [SD]) age, 42.2 ± 11.5 years, were included. Thirty healthy volunteers served as controls. We observed a significant difference in the levels of TLR2 expression in the CD14(+) HLA-DR(+) PB monocytes of patients with AD (mean [SD], 51.6 ± 23.1% and 264 ± 118 cells/mm(3)) at exacerbation (but not at the end of the 4-month postexacerbation period) compared with the healthy control subjects (mean [SD], 22.3 ± 10.6% and 105 ± 50 cells/mm(3); p < 0.001). TLR4 expression in PB monocytes was significantly greater in AD (mean [SD], 50.1 ± 20.9% and 275 ± 114 cells/mm(3)) than in the healthy subjects (mean [SD], 31.2 ± 8.7% and 147 ± 41 cells/mm(3); p < 0.001) both at exacerbation and at the 4-month postexacerbation period. Significant correlations between TLR2(+) (but not TLR4(+)) PB monocytes and the objective Scoring Atopic Dermatitis index (r = 0.604, p < 0.001), serum levels of IL-17a and TLR2(+) PB monocytes (r = 0.416, p = 0.027), and IL-4 and TLR2(+) PB monocytes (r = -0.307, p = 0.014) were observed during AD exacerbation. CONCLUSION: PB CD14(+) HLA-DR(+) TLR2(+) monocytes might have a role in the skewing of a T-helper 2/T-helper 17-mediated immune response during AD flare.

Anticytokine autoantibodies in chronic rhinosinusitis.

BACKGROUND: Anticytokine autoantibodies (AAbs) involve a great panel of cytokines both in healthy subjects and in patients with various diseases, but their incidence and pathophysiologic role are widely debated. The issue of AAbs in chronic rhinosinusitis (CRS) has never been explored. OBJECTIVE: The aim of the study was to check AAbs in patients with CRS and with nasal polyps (CRSwNP) and patients with CRS and without nasal polyps (CRSsNP). METHODS: One-hundred subjects with CRS and 40 healthy controls were included. CRS severity was determined by the 22-item Sino-Nasal Outcome Test and Lund-Mackay scores. Levels of immunoglobulin A (IgA), secretory IgA, IgG, IgE, interleukin (IL) 1ß, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and IL-17A, and AAbs levels in subjects' serum and nasal secretions (NS) were measured by the enzyme-linked immunosorbent assay. RESULTS: Forty-six patients with CRSsNP, 25 women (54.3%) and 21 men (45.7%), mean (standard deviation [SD]) ages 34.1 ± 12.3 years; and 54 patients with CRSwNP, 24 women (44.4%) and 30 men (55.6%), mean (SD) ages 37.9 ± 17.5 years. A group of 40 healthy subjects served as controls. In both CRSsNP and CRSwNP groups, serum and NS IL-1ß, IL-4, IL-5, IL-6, IL-8, IL-10, and IL-17A levels were higher compared with healthy controls, but there was no difference in the serum levels of cytokines between the CRSsNP and CRSwNP groups. Binding IgA antibodies against IL-1ß, IL-2, IL-5, and IL-8 were found at low levels in NS of both patients with CRSsNP and patients with CRSwNP. The highest levels of AAbs were detected against IL-5 (0.43 ± 0.38 optical density values) and IL-17A (0.51 ± 0.32 optical density values) in NS of patients with CRSwNP. In the CRSwNP group, a positive correlation was found between NS IL-5 and anti-IL-5 AAbs (r = 545; p < 0.001). Positive correlations between anti-IL-5 AAbs with NS total IgE (r = 0.424; p = 0.001) and with NS secretory IgA (r = 0.545; p < 0.001) were noted in the CRSwNP group. CONCLUSIONS: In patients with CRS, IgA class AAbs were detected in NS, whereas the highest levels of anti-IL-5 and anti-IL-17A AAbs were detected in patients with CRSwNP. Maybe these AAbs indicate disruption of immune tolerance and mucosal autoimmunity.

Functions of RNAi Pathways in Ribosomal RNA Regulation.

Argonaute proteins, guided by small RNAs, play crucial roles in gene regulation and genome protection through RNA interference (RNAi)-related mechanisms. Ribosomal RNAs (rRNAs), encoded by repeated rDNA units, constitute the core of the ribosome being the most abundant cellular transcripts. rDNA clusters also serve as sources of small RNAs, which are loaded into Argonaute proteins and are able to regulate rDNA itself or affect other gene targets. In this review, we consider the impact of small RNA pathways, specifically siRNAs and piRNAs, on rRNA gene regulation. Data from diverse eukaryotic organisms suggest the potential involvement of small RNAs in various molecular processes related to the rDNA transcription and rRNA fate. Endogenous siRNAs are integral to the chromatin-based silencing of rDNA loci in plants and have been shown to repress rDNA transcription in animals. Small RNAs also play a role in maintaining the integrity of rDNA clusters and may function in the cellular response to rDNA damage. Studies on the impact of RNAi and small RNAs on rRNA provide vast opportunities for future exploration.

Repression of interrupted and intact rDNA by the SUMO pathway in Drosophila melanogaster.

Ribosomal RNAs (rRNAs) are essential components of the ribosome and are among the most abundant macromolecules in the cell. To ensure high rRNA level, eukaryotic genomes contain dozens to hundreds of rDNA genes, however, only a fraction of the rRNA genes seems to be active, while others are transcriptionally silent. We found that individual rDNA genes have high level of cell-to-cell heterogeneity in their expression in Drosophila melanogaster. Insertion of heterologous sequences into rDNA leads to repression associated with reduced expression in individual cells and decreased number of cells expressing rDNA with insertions. We found that SUMO (Small Ubiquitin-like Modifier) and SUMO ligase Ubc9 are required for efficient repression of interrupted rDNA units and variable expression of intact rDNA. Disruption of the SUMO pathway abolishes discrimination of interrupted and intact rDNAs and removes cell-to-cell heterogeneity leading to uniformly high expression of individual rDNA in single cells. Our results suggest that the SUMO pathway is responsible for both repression of interrupted units and control of intact rDNA expression.

Neuron-specific enolase in nasal secretions as a novel biomarker of olfactory dysfunction in chronic rhinosinusitis.

BACKGROUND: Olfactory dysfunction is a diagnostic criterion for chronic rhinosinusitis (CRS). During chronic inflammation and olfactory neuronal damage in CRS, it is likely that neuron-specific enolase (NSE) can leak into nasal secretions (NS) and serum. Therefore, we postulated that NSE levels in NS and in circulation may be indicative of olfactory dysfunction in CRS. OBJECTIVE: To evaluate the relationship between the NS and serum concentrations of NSE with olfactory dysfunction in subjects with CRS. METHODS: The patients with CRS were classified into two groups, depending on the presence of polyps: CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP). A group of age- and sex-matched healthy volunteers served as controls. Olfactory function assessment was performed by using Sniffin' Sticks. NSE concentrations in serum and NS were analyzed by using the enzyme immunometric assay kit specific for the γ subunit. RESULTS: The study included 46 patients with CRSsNP, 25 women (54.3%) and 21 men (45.7%), mean (standard deviation [SD]) age, 34.1 ± 12.3 years; and 54 patients with CRSwNP, 24 women (44.4%) and 30 men (55.6%), mean (SD) age, 37.9 ± 17.5 years. A group of 40 healthy volunteers who were matched for age and sex served as controls. Significantly higher serum and NS levels of NSE were measured in patients with CRS compared with healthy controls (p < 0.001). In the CRSwNP group, both mean (SD) serum (83.5 ± 37.6 ng/mL) and mean (SD) NS (6.1 ± 2.3 ng/mL) levels of NSE were significantly higher than in the CRSsNP group (46.4 ± 7.3 ng/mL [p < 0.001] and 1.7 ± 0.5 ng/mL [p < 0.001], respectively). In both the CRSsNP and CRSwNP groups (but not in the healthy controls), significant negative correlations between NS NSE levels and TDI scores (r = -0.63, p < 0.001 for the CRSwNP group, and r = -0.51, p < 0.001 for CRSsNP group) were observed, which meant that higher NSE was associated with worse olfactory function. CONCLUSIONS: The study demonstrated a contribution of CRS to NSE and olfactory dysfunction.

Heat shock protein 70 and anti-heat shock protein 70 antibodies in nasal secretions of patients with chronic rhinosinusitis.

BACKGROUND: The issue of heat shock protein (HSP) 70 and anti-HSP70 antibodies in chronic rhinosinusitis (CRS) has never been explored. OBJECTIVE: To determine the nasal secretion (NS) levels of HSP70 and anti-HSP70 antibodies in patients with CRS with nasal polyps (CRSwNP) and patients with CRS without nasal polyps (CRSsNP), and to evaluate their associations with CRS clinical severity and correlation with NS interleukin (IL), IL-5 and interferon λ. METHODS: CRS severity was determined by Lund-Mackay scores. Levels of immunoglobulin E (IgE), IL-4, IL-5, interferon λ, HSP70, and anti-HSP70 antibody levels in NS were measured by enzyme-linked immunosorbent assay. RESULTS: Forty-six patients with CRSsNP (25 women [54.3%] and 21 men [45.7%], mean [standard deviation {SD}]) age, 34.1 ± 12.3 years; 54 patients with CRSwNP (24 women [44.4%] and 30 men [55.6%], mean [SD] age, 37.9 ± 17.5 years). A group of 40 healthy subjects served as controls. Compared with the controls (with a mean [SD] NS HSP70 level of 0.05 ± 0.03 µg/mL), mean [SD] NS HSP70 levels in both the CRSsNP group (0.16 ± 0.07 µg/mL) and CRSwNP group (0.21 ± 0.10 µg/mL) were increased (p < 0.001). Similarly, the mean (SD) NS anti-HSP70 antibody levels were significantly higher in patients with CRSwNP (0.25 ± 0.09 optical density value [ODV]) compared with CRSsNP (0.13 ± 0.04 ODV) (p < 0.001) and healthy controls (0.14 ± 0.02 ODV) (p < 0.001). NS HSP70 in subjects with CRSwNP showed a significant positive correlation with the Lund-Mackay score (r = 0.31; p < 0.05). NS levels of either HSP70 or anti-HSP70 antibodies were strongly correlated with NS IL-4 in the CRSwNP group (r = 0.62, p < 0.001; and r = 0.69, p < 0.001, respectively). CONCLUSION: NS concentrations of HSP70 and secretory IgA anti HSP70 antibodies are increased in CRSwNP (but not in CRSsNP) and correlate positively with the Lund-Mackay score, NS IL-4, and NS IL-5.