scholarly journals Truncated Hemoglobins 1 and 2 Are Implicated in the Modulation of Phosphorus Deficiency-Induced Nitric Oxide Levels in Chlamydomonas

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 947 ◽  
Author(s):  
Valentina Filina ◽  
Alexandra Grinko ◽  
Elena Ermilova

Truncated hemoglobins (trHbs) form a widely distributed family of proteins found in archaea, bacteria, and eukaryotes. Accumulating evidence suggests that trHbs may be implicated in functions other than oxygen delivery, but these roles are largely unknown. Characterization of the conditions that affect trHb expression and investigation of their regulatory mechanisms will provide a framework for elucidating the functions of these globins. Here, the transcription of Chlamydomonas trHb genes (THB1–12) under conditions of phosphorus (P) deprivation was analyzed. Three THB genes, THB1, THB2, and THB12 were expressed at the highest level. For the first time, we demonstrate the synthesis of nitric oxide (NO) under P-limiting conditions and the production of NO by cells via a nitrate reductase-independent pathway. To clarify the functions of THB1 and THB2, we generated and analyzed strains in which these THBs were strongly under-expressed by using an artificial microRNA approach. Similar to THB1 knockdown, the depletion of THB2 led to a decrease in cell size and chlorophyll levels. We provide evidence that the knockdown of THB1 or THB2 enhanced NO production under P deprivation. Overall, these results demonstrate that THB1 and THB2 are likely to contribute, at least in part, to acclimation responses in P-deprived Chlamydomonas.

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Nicholas W. Mathy ◽  
Olivia Burleigh ◽  
Andrew Kochvar ◽  
Erin R. Whiteford ◽  
Matthew Behrens ◽  
...  

Abstract Background Microglia are resident immunocompetent and phagocytic cells in the CNS. Pro-inflammatory microglia, stimulated by microbial signals such as bacterial lipopolysaccharide (LPS), viral RNAs, or inflammatory cytokines, are neurotoxic and associated with pathogenesis of several neurodegenerative diseases. Long non-coding RNAs (lncRNA) are emerging as important tissue-specific regulatory molecules directing cell differentiation and functional states and may help direct proinflammatory responses of microglia. Characterization of lncRNAs upregulated in proinflammatory microglia, such as NR_126553 or 2500002B13Rik, now termed Nostrill (iNOS Transcriptional Regulatory Intergenic LncRNA Locus) increases our understanding of molecular mechanisms in CNS innate immunity. Methods Microglial gene expression array analyses and qRT-PCR were used to identify a novel long intergenic non-coding RNA, Nostrill, upregulated in LPS-stimulated microglial cell lines, LPS-stimulated primary microglia, and LPS-injected mouse cortical tissue. Silencing and overexpression studies, RNA immunoprecipitation, chromatin immunoprecipitation, chromatin isolation by RNA purification assays, and qRT-PCR were used to study the function of this long non-coding RNA in microglia. In vitro assays were used to examine the effects of silencing the novel long non-coding RNA in LPS-stimulated microglia on neurotoxicity. Results We report here characterization of intergenic lncRNA, NR_126553, or 2500002B13Rik now termed Nostrill (iNOS Transcriptional Regulatory Intergenic LncRNA Locus). Nostrill is induced by LPS stimulation in BV2 cells, primary murine microglia, and in cortical tissue of LPS-injected mice. Induction of Nostrill is NF-κB dependent and silencing of Nostrill decreased inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in BV2 and primary microglial cells. Overexpression of Nostrill increased iNOS expression and NO production. RNA immunoprecipitation assays demonstrated that Nostrill is physically associated with NF-κB subunit p65 following LPS stimulation. Silencing of Nostrill significantly reduced NF-κB p65 and RNA polymerase II recruitment to the iNOS promoter and decreased H3K4me3 activating histone modifications at iNOS gene loci. In vitro studies demonstrated that silencing of Nostrill in microglia reduced LPS-stimulated microglial neurotoxicity. Conclusions Our data indicate a new regulatory role of the NF-κB-induced Nostrill and suggest that Nostrill acts as a co-activator of transcription of iNOS resulting in the production of nitric oxide by microglia through modulation of epigenetic chromatin remodeling. Nostrill may be a target for reducing the neurotoxicity associated with iNOS-mediated inflammatory processes in microglia during neurodegeneration.


2002 ◽  
Vol 283 (2) ◽  
pp. R496-R504 ◽  
Author(s):  
Harshini Mukundan ◽  
Thomas C. Resta ◽  
Nancy L. Kanagy

Exposure to chronic hypoxia induces erythropoietin (EPO) production to facilitate oxygen delivery to hypoxic tissues. Previous studies from our laboratory found that ovariectomy (OVX) exacerbates the polycythemic response to hypoxia and treatment with 17β-estradiol (E2-β) inhibits this effect. We hypothesized that E2-β decreases EPO gene expression during hypoxia. Because E2-β can induce nitric oxide (NO) production and NO can attenuate EPO synthesis, we further hypothesized that E2-β inhibition of EPO gene expression is mediated by NO. These hypotheses were tested in OVX catheterized rats treated with E2-β (20 μg/day) or vehicle for 14 days and exposed to 8 or 12 h of hypoxia (12% O2) or normoxia. We found that E2-β treatment significantly decreased EPO synthesis and gene expression during hypoxia. E2-β treatment did not induce endothelial NO synthase (eNOS) expression in the kidney but potentiated hypoxia-induced increases in plasma nitrates. We conclude that E2-β decreases hypoxic induction of EPO. However, this effect does not appear to be related to changes in renal eNOS expression.


2002 ◽  
Vol 53 (366) ◽  
pp. 103-110 ◽  
Author(s):  
Peter Rockel ◽  
Frank Strube ◽  
Andra Rockel ◽  
Juergen Wildt ◽  
Werner M. Kaiser

2002 ◽  
Vol 282 (2) ◽  
pp. F316-F323 ◽  
Author(s):  
Marcella M. Hallemeesch ◽  
Peter B. Soeters ◽  
Nicolaas E. P. Deutz

The kidney has an important function in arginine metabolism, because the kidney is the main endogenous source for de novo arginine production from circulating citrulline. In conditions such as sepsis, nitric oxide (NO) production is increased and is dependent on extracellular arginine availability. To elucidate the adaptive role of renal de novo arginine synthesis in a condition of increased NO production, we studied renal arginine metabolism in a mouse model of endotoxemia. Because arginine flux is largely dependent on protein flux, we also measured protein metabolism in mice. Female mice were injected intraperitoneally with lipopolysaccharide; control mice received 0.9% NaCl. Six hours later, renal blood flow was measured with the use of para-aminohippuric acid. Arginine and protein metabolism were studied using organ-balance, stable-isotope techniques. Systemic NO production was increased in the endotoxin-treated mice. In addition, renal protein synthesis and de novo arginine production from citrulline were increased. However, no effect on renal NO production was observed. In conclusion, increased renal de novo arginine production may serve to sustain systemic NO production. To our knowledge, it was shown for the first time that renal protein synthesis is enhanced in the early response to endotoxemia.


Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 257
Author(s):  
Seong Su Hong ◽  
Ji Eun Lee ◽  
Yeon Woo Jung ◽  
Ju-Hyoung Park ◽  
Jung A. Lee ◽  
...  

In our search for novel plant-derived inhibitors of nitric oxide (NO) with potential for treating inflammatory diseases, the phytochemicals of Amomum tsao-ko fruits were investigated, leading to the isolation of one bicyclic nonane (1), three menthene skeleton monoterpenoids (2–4), and two acyclic monoterpenoids (5 and 6). Their structures were identified using one- and two-dimensional nuclear magnetic resonance spectroscopy, and mass spectrometry. To the best of our knowledge, compounds 2–5 were obtained from the genus Amomum for the first time. All isolates were tested for their ability to inhibit lipopolysaccharide-stimulated NO overproduction in RAW264.7 cells. Compound 4 was found to inhibit NO production. Western blotting analysis indicated that active compound 4 can regulate inducible NO synthase expression. In addition, lipopolysaccharide-induced interleukin 1 beta and interleukin-6 overproduction was reduced in a concentration-dependent manner.


1996 ◽  
Vol 271 (4) ◽  
pp. C1244-C1249 ◽  
Author(s):  
C. V. Oddis ◽  
M. S. Finkel

Metabolic requirements for the production of nitric oxide (NO) by cytokine-stimulated neonatal rat cardiac myocytes (CM) were studied. CM were cultured for 48 h in media containing interleukin-1 beta (IL-1 beta) and free fatty acids. Removal of glucose from the media partially inhibited IL-1 beta-stimulated nitrite (NO2-) production [8.1 +/- 0.3 vs. 4.4 +/- 0.6 nmol.(1.25 X 10(5) cells)-1.48 h-1; P < 0.01; n = 12]. The glycolytic inhibitor 2-deoxy-D-glucose (2-DG) completely inhibited IL-1 beta-stimulated NO2- production [0.7 +/- 0.5 nmol.(1.25 X 10(5) cells)-1.48 h-1; P < 0.01; n = 12]. The addition of the glycolytic end product, pyruvate, completely blocked the 2-DG inhibition of IL-1 beta-stimulated NO2- production [7.4 +/- 0.4 nmol.(1.25 X 10(5) cells)-1.48 h-1; P < 0.01; n = 12]. Pyruvate alone did not significantly enhance NO2- production in the presence or absence of glucose (n = 12). The inactive analogue 3-O-methylglucose had no effect on NO2- production (n = 12). Reverse transcription-polymerase chain reaction revealed that pyruvate blocked 2-DG inhibition of inducible NO synthase mRNA expression. Neither 2-DG nor pyruvate had any effect on GTP-cyclohydrolase I mRNA expression in CM. We report for the first time that optimal IL-1 beta-stimulated NO production by CM requires both glucose and the glycolytic end product pyruvate.


2007 ◽  
Vol 22 (4) ◽  
pp. 243-250 ◽  
Author(s):  
Beatriz Martins Tavares-Murta ◽  
Adriana Oliveira Cordeiro ◽  
Eddie Fernando Candido Murta ◽  
Fernando de Queiroz Cunha ◽  
Flora Margarida Barra Bisinotto

PURPOSE: To investigate the effects of different conditions used during cardiopulmonary bypass (CPB) surgery on accompanying production of cytokine and nitric oxide (NO). METHODS: Patients undergoing CPB for the first time were prospectively enrolled and divided into two groups according to CPB parameters performed: i) normothermia (36.5-37°C) with blood cardioplegia (NB group, n=10) and ii) hypothermia (29-31°C) with crystalloid cardioplegia (HC group, n=10). Plasma samples obtained following intubation (baseline), during (5 and 30 min) and after (4 and 24 h) CPB were assayed for cytokines (ELISA) and NO metabolites (Griess reaction). RESULTS: Peak concentrations of interleukin (IL)-6 and IL-8 were reached at 4 h post CPB in both groups, but in the HC group those levels increased earlier and persisted for longer (24 h) compared to baseline (P < 0.05). IL-10 levels also increased at 4 h compared to baseline, but only significantly so in the HC group. NO metabolites were reduced in HC group at all time points compared to baseline (P < 0.05), while no significant differences were detected in the NB group. CONCLUSION: The association between increased systemic levels of cytokines and reduced NO production in the HC group suggests that different myocardial protection and/or perfusion temperature used during CPB may contribute to the extent of inflammatory response.


2019 ◽  
Vol 20 (6) ◽  
pp. 1368 ◽  
Author(s):  
Peipei Zhang ◽  
Shuangshuang Li ◽  
Pengcheng Zhao ◽  
Zhenfei Guo ◽  
Shaoyun Lu

The role of nitric oxide (NO) signaling in the cold acclimation of forage legumes was investigated in this study. Medicago sativa subsp. falcata (L.) Arcang. (hereafter M. falcata) is a forage legume with a higher cold tolerance than Medicago truncatula, a model legume. Cold acclimation treatment resulted in increased cold tolerance in both M. falcata and M. truncatula, which was suppressed by pretreatment with tungstate, an inhibitor of nitrate reductase (NR), and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), a scavenger of NO. Likely, NITRATE REDUCTASE 1 (NIA1), but not NIA2 transcript, NR activity, and NO production were increased after cold treatment. Treatments with exogenous NO donors resulted in increased cold tolerance in both species. Superoxide dismutase (SOD), catalase (CAT), and ascorbate-peroxidase (APX) activities and Cu,Zn-SOD2, Cu,Zn-SOD3, cytosolic APX1 (cAPX1), cAPX3 and chloroplastic APX1 (cpAPX1) transcript levels were induced in both species after cold treatment, which was suppressed by tungstate and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). Treatment with exogenous NO resulted in enhanced activities of SOD, CAT, and APX. Moreover, higher levels of NIA1 transcript, NR activity, NO production, and antioxidant enzyme activities and transcripts were observed in M. falcata as compared with M. truncatula after cold treatment. The results suggest that NR-derived NO production and upregulated antioxidant defense are involved in cold acclimation in both species, while the higher levels of NO production and its derived antioxidant enzymes are associated with the higher cold tolerance in M. falcata as compared with M. truncatula.


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