The cold atmospheric pressure plasma-generated species superoxide, singlet oxygen and atomic oxygen activate the molecular chaperone Hsp33.

Cold atmospheric pressure plasmas are used for surface decontamination or disinfection, e.g. in clinical settings. Protein aggregation has been shown to significantly contribute to the antibacterial mechanisms of plasma. To investigate the potential role of the redox-activated zinc-binding chaperone Hsp33 in preventing protein aggregation and thus mediating plasma resistance, we compared the plasma sensitivity of wild-type E. coli to that of an hslO deletion mutant lacking Hsp33 as well as an over-producing strain. Over-production of Hsp33 increased plasma survival rates above wild-type levels. Hsp33 was previously shown to be activated by plasma in vitro. For the PlasmaDerm source applied in dermatology, reversible activation of Hsp33 was confirmed. Thiol oxidation and Hsp33 unfolding, both crucial for Hsp33 activation, occurred during plasma treatment. After prolonged plasma exposure, however, unspecific protein oxidation was detected, the ability of Hsp33 to bind zinc ions was decreased without direct modifications of the zinc-binding motif, and the protein was inactivated. To identify chemical species of potential relevance for plasma-induced Hsp33 activation, reactive oxygen species were tested for their ability to activate Hsp33 in vitro. Superoxide, singlet oxygen and potentially atomic oxygen activate Hsp33, while no evidence was found for activation by ozone, peroxynitrite or hydroxyl radicals.

Deficiency in the DNA repair protein ERCC1 triggers a link between senescence and apoptosis in human fibroblasts and mouse skin.

ERCC1 (excision repair cross complementing-group 1) is a mammalian endonuclease that incises the damaged strand of DNA during nucleotide excision repair and interstrand cross-link repair. Ercc1-/Δ mice, carrying one null and one hypomorphic Ercc1 allele, have been widely used to study aging due to accelerated aging phenotypes in numerous organs and their shortened lifespan. Ercc1-/Δ mice display combined features of human progeroid and cancer-prone syndromes. Although several studies report cellular senescence and apoptosis associated with the premature aging of Ercc1-/Δ mice, the link between these two processes and their physiological relevance in the phenotypes of Ercc1-/Δ mice are incompletely understood. Here, we show that ERCC1 depletion, both in cultured human fibroblasts and the skin of Ercc1-/Δ mice, initially induces cellular senescence and, importantly, increased expression of several SASP (senescence-associated secretory phenotype) factors. Cellular senescence induced by ERCC1 deficiency was dependent on activity of the p53 tumor-suppressor protein. In turn, TNFα secreted by senescent cells induced apoptosis, not only in neighboring ERCC1-deficient nonsenescent cells, but also cell autonomously in the senescent cells themselves. In addition, expression of the stem cell markers p63 and Lgr6 was significantly decreased in Ercc1-/Δ mouse skin, where the apoptotic cells are localized, compared to age-matched wild-type skin, possibly due to the apoptosis of stem cells. These data suggest that ERCC1-depleted cells become susceptible to apoptosis via TNFα secreted from neighboring senescent cells. We speculate that parts of the premature aging phenotypes and shortened health- or lifespan may be due to stem cell depletion through apoptosis promoted by senescent cells.

Ultrasound measurements of subcutaneous adipose tissue thickness show sexual dimorphism in children of three to five years of age.

AIM: A standard approach to measure subcutaneous adipose tissue (SAT) using ultrasound has proved successful in adults, but has not been studied in children. This study addressed that gap in children aged three to five years. METHODS: In autumn 2016, 24 preschools in Southwest Germany, recruited via mail, agreed to take part in this study and 274 children (51.4% boys) with a mean age of 4.6 ± 0.7 years participated in measurements of SAT and anthropometry. Differences in measurements were explored between the sexes and anthropometric predictors of mean SAT thickness were identified. Intra-observer reliability for ultrasound measurements of SAT was also assessed. RESULTS: The mean SAT thickness showed significant differences between the boys and girls (5.3 ± 2.0 and 6.3 ± 2.0 mm, respectively, p < 0.01). The children's body mass, height and sex explained 66% of the variance in the mean SAT thickness, as SAT was larger with a higher body mass, a smaller stature and in girls. Intra-observer reliability resulted in an intra-class correlation coefficient of 0.994 (p < 0.01) with a 95% confidence interval of 0.983-0.998. CONCLUSION: Subcutaneous adipose tissue thickness differed between boys and girls with a mean age of 4.6 years. Intra-observer reliability was excellent. This standardised approach enabled high-precision measurements of SAT in a paediatric population.

The RNA-Binding Proteins Zfp36l1 and Zfp36l2 Enforce the Thymic ß-Selection Checkpoint by Limiting DNA Damage Response Signaling and Cell Cycle Progression.

The RNA-binding proteins Zfp36l1 and Zfp36l2 act redundantly to enforce the ß-selection checkpoint during thymopoiesis, yet their molecular targets remain largely unknown. In this study, we identify these targets on a genome-wide scale in primary mouse thymocytes and show that Zfp36l1/l2 regulate DNA damage response and cell cycle transcripts to ensure proper ß-selection. Double-negative 3 thymocytes lacking Zfp36l1/l2 share a gene expression profile with postselected double-negative 3b cells despite the absence of intracellular TCRß and reduced IL-7 signaling. Our findings show that in addition to controlling the timing of proliferation at ß-selection, posttranscriptional control by Zfp36l1/l2 limits DNA damage responses, which are known to promote thymocyte differentiation. Zfp36l1/l2 therefore act as posttranscriptional safeguards against chromosomal instability and replication stress by integrating pre-TCR and IL-7 signaling with DNA damage and cell cycle control.

Cleavage of roquin and regnase-1 by the paracaspase MALT1 releases their cooperatively repressed targets to promote T(H)17 differentiation.

Humoral autoimmunity paralleled by the accumulation of follicular helper T cells (T(FH) cells) is linked to mutation of the gene encoding the RNA-binding protein roquin-1. Here we found that T cells lacking roquin caused pathology in the lung and accumulated as cells of the T(H)17 subset of helper T cells in the lungs. Roquin inhibited T(H)17 cell differentiation and acted together with the endoribonuclease regnase-1 to repress target mRNA encoding the T(H)17 cell-promoting factors IL-6, ICOS, c-Rel, IRF4, IκBNS and IκBζ. This cooperation required binding of RNA by roquin and the nuclease activity of regnase-1. Upon recognition of antigen by the T cell antigen receptor (TCR), roquin and regnase-1 proteins were cleaved by the paracaspase MALT1. Thus, this pathway acts as a 'rheostat' by translating TCR signal strength via graded inactivation of post-transcriptional repressors and differential derepression of targets to enhance T(H)17 differentiation.

Roquin paralogs 1 and 2 redundantly repress the Icos and Ox40 costimulator mRNAs and control follicular helper T cell differentiation.

The Roquin-1 protein binds to messenger RNAs (mRNAs) and regulates gene expression posttranscriptionally. A single point mutation in Roquin-1, but not gene ablation, increases follicular helper T (Tfh) cell numbers and causes lupus-like autoimmune disease in mice. In T cells, we did not identify a unique role for the much lower expressed paralog Roquin-2. However, combined ablation of both genes induced accumulation of T cells with an effector and follicular helper phenotype. We showed that Roquin-1 and Roquin-2 proteins redundantly repressed the mRNA of inducible costimulator (Icos) and identified the Ox40 costimulatory receptor as another shared mRNA target. Combined acute deletion increased Ox40 signaling, as well as Irf4 expression, and imposed Tfh differentiation on CD4(+) T cells. These data imply that both proteins maintain tolerance by preventing inappropriate T cell activation and Tfh cell differentiation, and that Roquin-2 compensates in the absence of Roquin-1, but not in the presence of its mutated form.

Molecular control of Tfh-cell differentiation by Roquin family proteins.

Post-transcriptional gene regulation by RNA-binding proteins is a fast and effective way to adapt gene expression and change cellular responses. These trans-acting factors have been involved in a number of cell fate decisions, and their mutation is often associated with the development of disease. The RNA-binding protein Roquin-1 has been found to be crucial in the maintenance of peripheral tolerance and the prevention of autoimmune disease. This review describes the molecular role of Roquin family proteins in the control of follicular T-helper cell differentiation. Here, we discuss the redundant regulation of Icos and Ox40 costimulatory receptor mRNAs by Roquin-1 and Roquin-2 proteins. A major focus is placed on the distinct activity of Roquin-1 or Roquin-2 proteins in the mouse models of conditional gene targeting. These recent data are then integrated into an interpretation of altered Roquin protein function in the sanroque mouse that expresses the Roquin-1 protein with just one amino acid substitution and, different from the Roquin-1-deficient mouse, develops lupus-like autoimmune disease.

Roquin binds inducible costimulator mRNA and effectors of mRNA decay to induce microRNA-independent post-transcriptional repression.

The molecular mechanism by which roquin controls the expression of inducible costimulator (ICOS) to prevent autoimmunity remains unsolved. Here we show that in helper T cells, roquin localized to processing (P) bodies and downregulated ICOS expression. The repression was dependent on the RNA helicase Rck, and roquin interacted with Rck and the enhancer of decapping Edc4, which act together in mRNA decapping. Sequences in roquin that confer P-body localization were essential for roquin-mediated ICOS repression. However, this process did not require microRNAs or the RNA-induced silencing complex (RISC). Instead, roquin bound ICOS mRNA directly, showing an intrinsic preference for a previously unrecognized sequence in the 3' untranslated region (3' UTR). Our results support a model in which roquin controls ICOS expression through binding to the 3' UTR of ICOS mRNA and by interacting with proteins that confer post-transcriptional repression.