Loss of RNA binding protein HuD facilitates the production of the senescence-associated secretory phenotype

HuD, an RNA binding protein, plays a role in the regulation of gene expression in certain types of cells, including neuronal cells and pancreatic β-cells, via RNA metabolism. Its aberrant expression is associated with the pathogenesis of several human diseases. To explore HuD-mediated gene regulation, stable cells expressing short hairpin RNA against HuD were established using mouse neuroblastoma Neuro2a (N2a) cells, which displayed enhanced phenotypic characteristics of cellular senescence. Two approaches, RNA immunoprecipitation (RNA IP)-NanoString profiling and cytokine array, were used to subsequently identify a subset of putative HuD targets that act as senescence-associated secretory phenotype (SASP), including C-C motif ligand 2 (CCL2), CCL20, C-X-C motif chemokine ligand 2 (CXCL2), and interleukin-6 (IL-6). Here, we further demonstrated that HuD regulates the expression of CCL2, a SASP candidate upregulated in cells following HuD knockdown, by binding to the 3′-untranslated region (UTR) of Ccl2 mRNA. Downregulation of HuD increased the level of CCL2 in N2a cells and the brain tissues of HuD knockout (KO) mice. Exposure to γ-irradiation induced cellular senescence in N2a cells and HuD knockdown facilitated stress-induced cellular senescence. Our results reveal that HuD acts as a novel regulator of CCL2 expression, and its aberrant expression may contribute to cellular senescence by regulating SASP production.Subject terms: Senescence, RNA quality control     

Nicotinamide riboside and caffeine partially restore diminished NAD availability but not altered energy metabolism in Alzheimer's disease

The redox co‐factor nicotinamide adenine dinucleotide (NAD) declines with age, and NAD deficits are specifically associated with dysfunctional energy metabolism in late‐onset Alzheimer''s disease (LOAD). Nicotinamide riboside (NR), a dietary NAD precursor, has been suggested to ameliorate the aging process or neurodegeneration. We assessed whether NR with or without caffeine, which increases nicotinamide mononucleotide transferase subtype 2 (NMNAT2), an essential enzyme in NAD production, modulates bioenergetic functions in LOAD. In LOAD patients—and young or old control individuals—derived dermal fibroblasts as well as in induced pluripotent stem cell‐differentiated neural progenitors and astrocytes, NR and caffeine cell type‐specifically increased the NAD pool, transiently enhanced mitochondrial respiration or glycolysis and altered the expression of genes in the NAD synthesis or consumption pathways. However, continued treatment led to reversed bioenergetic effects. Importantly, NR and caffeine did not alter the characteristics of a previously documented inherent LOAD‐associated bioenergetic phenotype. Thus, although NR and caffeine can partially restore diminished NAD availability, increasing NAD alone may not be sufficient to boost or restore energy metabolism in brain aging or alter aberrant energy management in LOAD. Nicotinamide riboside might still be of value in combination with other agents in preventive or therapeutic intervention strategies to address the aging process or age‐associated dementia.     

Association of ischemic stroke onset time with presenting severity,acute progression,and long-term outcome: A cohort study

BackgroundPreclinical data suggest circadian variation in ischemic stroke progression, with more active cell death and infarct growth in rodent models with inactive phase (daytime) than active phase (nighttime) stroke onset. We aimed to examine the association of stroke onset time with presenting severity, early neurological deterioration (END), and long-term functional outcome in human ischemic stroke.Methods and findingsIn a Korean nationwide multicenter observational cohort study from May 2011 to July 2020, we assessed circadian effects on initial stroke severity (National Institutes of Health Stroke Scale [NIHSS] score at admission), END, and favorable functional outcome (3-month modified Rankin Scale [mRS] score 0 to 2 versus 3 to 6). We included 17,461 consecutive patients with witnessed ischemic stroke within 6 hours of onset. Stroke onset time was divided into 2 groups (day-onset [06:00 to 18:00] versus night-onset [18:00 to 06:00]) and into 6 groups by 4-hour intervals. We used mixed-effects ordered or logistic regression models while accounting for clustering by hospitals. Mean age was 66.9 (SD 13.4) years, and 6,900 (39.5%) were women. END occurred in 2,219 (12.7%) patients. After adjusting for covariates including age, sex, previous stroke, prestroke mRS score, admission NIHSS score, hypertension, diabetes, hyperlipidemia, smoking, atrial fibrillation, prestroke antiplatelet use, prestroke statin use, revascularization, season of stroke onset, and time from onset to hospital arrival, night-onset stroke was more prone to END (adjusted incidence 14.4% versus 12.8%, p = 0.006) and had a lower likelihood of favorable outcome (adjusted odds ratio, 0.88 [95% CI, 0.79 to 0.98]; p = 0.03) compared with day-onset stroke. When stroke onset times were grouped by 4-hour intervals, a monotonic gradient in presenting NIHSS score was noted, rising from a nadir in 06:00 to 10:00 to a peak in 02:00 to 06:00. The 18:00 to 22:00 and 22:00 to 02:00 onset stroke patients were more likely to experience END than the 06:00 to 10:00 onset stroke patients. At 3 months, there was a monotonic gradient in the rate of favorable functional outcome, falling from a peak at 06:00 to 10:00 to a nadir at 22:00 to 02:00. Study limitations include the lack of information on sleep disorders and patient work/activity schedules.ConclusionsNight-onset strokes, compared with day-onset strokes, are associated with higher presenting neurologic severity, more frequent END, and worse 3-month functional outcome. These findings suggest that circadian time of onset is an important additional variable for inclusion in epidemiologic natural history studies and in treatment trials of neuroprotective and reperfusion agents for acute ischemic stroke.

Wi-Sun Ryu and colleagues investigate the association of stroke onset time with presenting severity, early neurological deterioration (END), and long-term functional outcome in ischemic stroke.     

Colonisation of the oral cavity by periodontopathic bacteria in complete denture wearers

doi: 10.1111/j.1741‐2358.2011.00506.x Colonisation of the oral cavity by periodontopathic bacteria in complete denture wearers Objective: The purpose of this study was to investigate colonisation by periodontopathic bacteria and the sites of colonisation in elderly upper and lower complete denture wearers. We also investigated the relationship between level of oral hygiene and colonisation by periodontopathic bacteria. Materials and methods: Forty edentulous and 37 dentate volunteers participated in this study. Samples were collected from whole saliva, and levels of Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum were determined by PCR Invader technology. Detection of these species on oral mucosal and denture surfaces was performed by PCR. Fisher’s exact test was used for the statistical analysis. Cluster analysis was employed to investigate trends in the periodontopathic bacteria flora in each sampling area. Results: Detection rates of periodontopathic bacteria in whole saliva were lower under edentulous conditions than under dentulous conditions, except for A. actinomycetemcomitans and F. nucleatum (p < 0.01). Detection rate of F. nucleatum was the highest in all areas. A positive correlation was observed between DNA quantification of P. gingivalis and number of Candida species in saliva. Cluster analysis of the test species identified two clusters. Tongue‐coating status was associated with the detection rate of all periodontopathic bacteria investigated, and denture plaque status was associated with the detection rate of T. denticola and F. nucleatum. Conclusion: Results indicate the presence of periodontopathic bacteria under edentulous conditions and that the status of oral hygiene of the mucosal or denture surfaces affects colonisation by T. denticola and F. nucleatum.     

Regulation of poly(ADP-ribose) polymerase-1-dependent gene expression through promoter-directed recruitment of a nuclear NAD+ synthase

NMNAT-1 and PARP-1, two key enzymes in the NAD(+) metabolic pathway, localize to the nucleus where integration of their enzymatic activities has the potential to control a variety of nuclear processes. Using a variety of biochemical, molecular, cell-based, and genomic assays, we show that NMNAT-1 and PARP-1 physically and functionally interact at target gene promoters in MCF-7 cells. Specifically, we show that PARP-1 recruits NMNAT-1 to promoters where it produces NAD(+) to support PARP-1 catalytic activity, but also enhances the enzymatic activity of PARP-1 independently of NAD(+) production. Furthermore, using two-photon excitation microscopy, we show that NMNAT-1 catalyzes the production of NAD(+) in a nuclear pool that may be distinct from other cellular compartments. In expression microarray experiments, depletion of NMNAT-1 or PARP-1 alters the expression of about 200 protein-coding genes each, with about 10% overlap between the two gene sets. NMNAT-1 enzymatic activity is required for PARP-1-dependent poly(ADP-ribosyl)ation at the promoters of commonly regulated target genes, as well as the expression of those target genes. Collectively, our studies link the enzymatic activities of NMNAT-1 and PARP-1 to the regulation of a set of common target genes through functional interactions at target gene promoters.     

Glycolate oxidase modulates reactive oxygen species-mediated signal transduction during nonhost resistance in Nicotiana benthamiana and Arabidopsis

In contrast to gene-for-gene disease resistance, nonhost resistance governs defense responses to a broad range of potential pathogen species. To identify specific genes involved in the signal transduction cascade associated with nonhost disease resistance, we used a virus-induced gene-silencing screen in Nicotiana benthamiana, and identified the peroxisomal enzyme glycolate oxidase (GOX) as an essential component of nonhost resistance. GOX-silenced N. benthamiana and Arabidopsis thaliana GOX T-DNA insertion mutants are compromised for nonhost resistance. Moreover, Arabidopsis gox mutants have lower H(2)O(2) accumulation, reduced callose deposition, and reduced electrolyte leakage upon inoculation with hypersensitive response-causing nonhost pathogens. Arabidopsis gox mutants were not affected in NADPH oxidase activity, and silencing of a gene encoding NADPH oxidase (Respiratory burst oxidase homolog) in the gox mutants did not further increase susceptibility to nonhost pathogens, suggesting that GOX functions independently from NADPH oxidase. In the two gox mutants examined (haox2 and gox3), the expression of several defense-related genes upon nonhost pathogen inoculation was decreased compared with wild-type plants. Here we show that GOX is an alternative source for the production of H(2)O(2) during both gene-for-gene and nonhost resistance responses.     

Changes in the Pulmonary Function Test after Radioactive Iodine Treatment in Patients with Pulmonary Metastases of Differentiated Thyroid Cancer

ObjectivePulmonary function test (PFT) is a useful tool for an objective assessment of respiratory function. Impaired pulmonary function is critical for the survival and quality of life in patients with pulmonary metastases of solid cancers including thyroid cancer. This study aimed to evaluate clinical factors associated with severely impaired pulmonary function by serial assessment with PFT in patients with pulmonary metastasis of differentiated thyroid cancer (DTC) who received radioactive iodine treatment (RAIT).PatientsThis retrospective study enrolled 31 patients who underwent serial PFTs before and after RAIT for pulmonary metastasis of DTC. We evaluated the risk factors for severe impairment of pulmonary function.ResultsThe median age of the patients was 44.1 years and 18 of them were female patients. Severe impairment of pulmonary function was observed in five patients (16%) after a median of three RAITs (cumulative I-131 activity = 20.4 GBq). These patients were older and more frequently had mild impairment of baseline pulmonary function, respiratory symptoms, or progressive disease compared with patients with stable pulmonary function. Neither cumulative dose nor number of RAIT was associated with decreased pulmonary function. Coexisting pulmonary diseases, presence of respiratory symptoms, and metastatic disease progression were significantly associated with severe decrease in forced vital capacity during follow-up (p =.047, p =.011, and p =.021, respectively).ConclusionsPulmonary function was severely impaired during follow-up in some patients with pulmonary metastasis of DTC after a high-dose RAITs. Neither the number of RAIT nor the cumulative I-131 activity was associated with decreased pulmonary function. Serial PFT might be considered for some high-risk patients during follow-up.     

A dual signaling cascade that regulates the ectodomain shedding of heparin-binding epidermal growth factor-like growth factor

Ectodomain shedding is an important mechanism to regulate the biological activities of membrane proteins. We focus here on the signaling mechanism of the ectodomain shedding of heparin-binding epidermal growth factor (EGF)-like growth factor (pro HB-EGF). Lysophosphatidic acid (LPA), a ligand for seven-transmembrane G protein-coupled receptors, stimulates the shedding of pro HB-EGF, which constitutes a G protein-coupled receptor-mediated transactivation of the EGF receptor. Experiments using a series of inhibitors and overexpression of mutant forms of signaling molecules revealed that the Ras-Raf-MEK signal is essential for the LPA-induced shedding. In addition, the small GTPase Rac is involved in the LPA-induced shedding, possibly to promote MEK activation. 12-O-Tetradecanoylphorbol-13-acetate is another potent inducer of pro HB-EGF shedding. We also demonstrate that the LPA-induced pathway is distinct from the 12-O-tetradecanoylphorbol-13-acetate-induced pathway and that these pathways constitute a dual signaling cascade that regulates the shedding of pro HB-EGF.     

Reduction of Bacillus cereus spores in sikhye, a traditional Korean rice beverage, by modified tyndallization processes with and without carbon dioxide injection

Aims: The objective of this study was to inactivate Bacillus cereus spores in sikhye using a modified tyndallization process involving injection with carbon dioxide (CO₂). Methods and Results: Heat tolerance of B. cereus spores in tryptic soy broth and sikhye was evaluated. The D_95°C values of the B. cereus spores were 2·8–4·9 min, dependent of type of heating medium or inoculum level. The lethality of conventional heat treatment and modified tyndallization with or without CO₂ injection against B. cereus spores in sikhye was determined. The order of effectiveness was modified tyndallization with CO₂ > modified tyndallization without CO₂ > conventional heat treatment. Modified tyndallization with CO₂ reduced the number of B. cereus spores in sikhye by 5·8 log CFU ml^?1. The increased CO₂ concentration and decreased pH of sikhye resulting from CO₂ injection rapidly reverted to near‐normal values after heat treatment. Conclusions: Modified tyndallization with CO₂ was more effective than conventional heat treatment or modified tyndallization without CO₂ in reducing B. cereus spores in sikhye. Significance and Impact of the Study: Results of this study will be useful when developing strategies to control B. cereus spores in sikhye and may have application to other beverages.