scholarly journals The effects of 6 hours of hypoxia on protein synthesis in rat tissues in vivo and in vitro

1985 ◽  
Vol 228 (1) ◽  
pp. 179-185 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Gastric Emptying ◽  
Skeletal Muscles ◽  
Rat Tissues ◽  
Tissue Nitrogen ◽  
The Brain ◽  
H Protein

Rates of protein synthesis were measured in vivo in several tissues (heart, skeletal muscles, liver, tibia, skin, brain, kidney, lung) of fed rats exposed to O2/N2 (1:9) for 6 h starting at 08:00-11:00 h. Protein synthesis rates were depressed by 15-35% compared with normoxic controls in all of the tissues studied. The decreases were greatest in the brain and the skin. Although hypoxia inhibited gastric emptying, its effects on protein synthesis could probably not be attributed to its induction of a starved state, because protein-synthesis rates in brain and skin were not decreased by a 15-18 h period of starvation initiated at 23:00 h. Furthermore, we showed that protein synthesis was inhibited by hypoxia in the rat heart perfused in vitro, suggesting a direct effect. The role of hypoxia in perturbing tissue nitrogen balance in various physiological and pathological states is discussed.

The use of siRNA as a pharmacological tool to assess a role for the transcription factor NF-IL6 in the brain under in vitro and in vivo conditions during LPS-induced inflammatory stimulation

2017 ◽  
Vol 28 (6) ◽  
Author(s):  
Jelena Damm ◽  
Joachim Roth ◽  
Rüdiger Gerstberger ◽  
Christoph Rummel
Keyword(s):  
Transcription Factor ◽  
Brain Cells ◽  
Nuclear Factor ◽  
Si Rna ◽  
The Brain ◽  
Deficient Mice ◽  
Transcription Factor Nuclear Factor

AbstractBackground:Studies with NF-IL6-deficient mice indicate that this transcription factor plays a dual role during systemic inflammation with pro- and anti-inflammatory capacities. Here, we aimed to characterize the role of NF-IL6 specifically within the brain.Methods:In this study, we tested the capacity of short interfering (si) RNA to silence the inflammatory transcription factor nuclear factor-interleukin 6 (NF-IL6) in brain cells underResults:In cells of a mixed neuronal and glial primary culture from the ratConclusions:This approach was, thus, not suitable to characterize the role NF-IL6 in the brain

scholarly journals Citrulline directly modulates muscle protein synthesis via the PI3K/MAPK/4E-BP1 pathway in a malnourished state: evidence from in vivo, ex vivo, and in vitro studies

2017 ◽  
Vol 312 (1) ◽  
pp. E27-E36 ◽  
Author(s):  
Servane Le Plénier ◽  
Arthur Goron ◽  
Athanassia Sotiropoulos ◽  
Eliane Archambault ◽  
Chantal Guihenneuc ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Ex Vivo ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fold Increase ◽  
Underlying Mechanism ◽  
Muscle Homeostasis

Citrulline (CIT) is an endogenous amino acid produced by the intestine. Recent literature has consistently shown CIT to be an activator of muscle protein synthesis (MPS). However, the underlying mechanism is still unknown. Our working hypothesis was that CIT might regulate muscle homeostasis directly through the mTORC1/PI3K/MAPK pathways. Because CIT undergoes both interorgan and intraorgan trafficking and metabolism, we combined three approaches: in vivo, ex vivo, and in vitro. Using a model of malnourished aged rats, CIT supplementation activated the phosphorylation of S6K1 and 4E-BP1 in muscle. Interestingly, the increase in S6K1 phosphorylation was positively correlated ( P < 0.05) with plasma CIT concentration. In a model of isolated incubated skeletal muscle from malnourished rats, CIT enhanced MPS (from 30 to 80% CIT vs. Ctrl, P < 0.05), and the CIT effect was abolished in the presence of wortmannin, rapamycin, and PD-98059. In vitro, on myotubes in culture, CIT led to a 2.5-fold increase in S6K1 phosphorylation and a 1.5-fold increase in 4E-BP1 phosphorylation. Both rapamycin and PD-98059 inhibited the CIT effect on S6K1, whereas only LY-294002 inhibited the CIT effect on both S6K1 and 4E-BP1. These findings show that CIT is a signaling agent for muscle homeostasis, suggesting a new role of the intestine in muscle mass control.

scholarly journals DR5 Knockout Mice Are Compromised in Radiation-Induced Apoptosis

2005 ◽  
Vol 25 (5) ◽  
pp. 2000-2013 ◽  
Author(s):  
Niklas Finnberg ◽  
Joshua J. Gruber ◽  
Peiwen Fei ◽  
Dorothea Rudolph ◽  
Anka Bric ◽  
...  
Keyword(s):  
Cell Death ◽  
Null Mouse ◽  
Organ Specific ◽  
Radiation Induced ◽  
Induced Apoptosis ◽  
The Brain ◽  
Necrosis Factor

ABSTRACT DR5 (also called TRAIL receptor 2 and KILLER) is an apoptosis-inducing membrane receptor for tumor necrosis factor-related apoptosis-inducing ligand (also called TRAIL and Apo2 ligand). DR5 is a transcriptional target of p53, and its overexpression induces cell death in vitro. However, the in vivo biology of DR5 has remained largely unexplored. To better understand the role of DR5 in development and in adult tissues, we have created a knockout mouse lacking DR5. This mouse is viable and develops normally with the exception of having an enlarged thymus. We show that DR5 is not expressed in developing embryos but is present in the decidua and chorion early in development. DR5-null mouse embryo fibroblasts expressing E1A are resistant to treatment with TRAIL, suggesting that DR5 may be the primary proapoptotic receptor for TRAIL in the mouse. When exposed to ionizing radiation, DR5-null tissues exhibit reduced amounts of apoptosis compared to wild-type thymus, spleen, Peyer's patches, and the white matter of the brain. In the ileum, colon, and stomach, DR5 deficiency was associated with a subtle phenotype of radiation-induced cell death. These results indicate that DR5 has a limited role during embryogenesis and early stages of development but plays an organ-specific role in the response to DNA-damaging stimuli.

scholarly journals The Two Faces of Ascorbate: Prooxidant Activity and Radio-Sensitisation

2021 ◽  
Author(s):  
◽  
Georgia Carson
Keyword(s):  
Dna Damage ◽  
Alternative Therapy ◽  
High Dose ◽  
Intravenous Injections ◽  
Unique Nature ◽  
Therapy Option ◽  
The Brain

<p>Although not recommended by mainstream oncologists, intravenous injections of pharmacological ascorbate are currently an alternative therapy option for cancer patients. Research has not yet determined whether high-dose ascorbate interacts favourably with radiation therapy to increase DNA damage, and therefore cell death in cancer. Some studies suggest that ascorbate can act as a prooxidant and increase the cytotoxic effect of irradiation in vitro. Glioblastoma multiforme (GBM) is a primary brain astrocytoma that is highly therapy resistant, so patients would be advantaged if ascorbate radiosensitised their cancer.  In this investigation, flow cytometry and single cell gel electrophoresis (comet tail assay) were used to measure three indicators of DNA damage in GBM cells in response to ascorbate and irradiation, and were contrasted with immunofluorescence-revealed DNA damage from an intracranial mouse model of GBM.   The pro-oxidant, radiosensitisation role of ascorbate was confirmed, as measured by H2AX, 8OHdG, and DSBs in vitro. With all three of these markers of DNA damage, combinations of irradiation and ascorbate had increased damage compared with individual treatments. However preliminary in vivo evidence indicates that increased DNA damage did not occur in an animal model of GBM, and in fact ascorbate may protect from DNA damage in an in vivo context.  These findings complement previous results from our lab, and serve to fill in gaps in knowledge specifically around the DNA damaging effects of ascorbate. The unique nature of the brain environment, as enclosed by the blood brain barrier, prevents translation of data from other non-brain cancer studies, as such, this investigation also contributes to the exploration of a much needed avenue of research. Considering the context of ascorbate treatment as a potentially harmful currently used adjuvant, it is imperative to confirm or disprove its efficacy in a clinically relevant environment.</p>

scholarly journals Antigenic and genetic characterization of a divergent African virus, Ikoma lyssavirus

2014 ◽  
Vol 95 (5) ◽  
pp. 1025-1032 ◽  
Author(s):  
Daniel L. Horton ◽  
Ashley C. Banyard ◽  
Denise A. Marston ◽  
Emma Wise ◽  
David Selden ◽  
...  
Keyword(s):  
Laboratory Mouse ◽  
Rabies Vaccine ◽  
Molecular Techniques ◽  
Phenotypic Characteristics ◽  
Nucleotide Divergence ◽  
The Brain

In 2009, a novel lyssavirus (subsequently named Ikoma lyssavirus, IKOV) was detected in the brain of an African civet (Civettictis civetta) with clinical rabies in the Serengeti National Park of Tanzania. The degree of nucleotide divergence between the genome of IKOV and those of other lyssaviruses predicted antigenic distinction from, and lack of protection provided by, available rabies vaccines. In addition, the index case was considered likely to be an incidental spillover event, and therefore the true reservoir of IKOV remained to be identified. The advent of sensitive molecular techniques has led to a rapid increase in the discovery of novel viruses. Detecting viral sequence alone, however, only allows for prediction of phenotypic characteristics and not their measurement. In the present study we describe the in vitro and in vivo characterization of IKOV, demonstrating that it is (1) pathogenic by peripheral inoculation in an animal model, (2) antigenically distinct from current rabies vaccine strains and (3) poorly neutralized by sera from humans and animals immunized against rabies. In a laboratory mouse model, no protection was elicited by a licensed rabies vaccine. We also investigated the role of bats as reservoirs of IKOV. We found no evidence for infection among 483 individuals of at least 13 bat species sampled across sites in the Serengeti and Southern Kenya.

Induction of PDCD4 by albumin in proximal tubule epithelial cells potentiates proteinuria-induced dysfunctional autophagy by negatively targeting Atg5

2021 ◽  
Author(s):  
Ezra Kombo Osoro ◽  
Xiaojuan Du ◽  
Dong Liang ◽  
Xi Lan ◽  
Riaz Farooq ◽  
...  
Keyword(s):  
Diabetic Kidney Disease ◽  
Rat Tissues ◽  
Disease Group ◽  
Potential Therapeutic Target ◽  
Programmed Cell Death 4 ◽  
Precise Molecular Mechanism

The precise molecular mechanism of autophagy dysfunction in type 1 diabetes is not known. Herein, the role of programmed cell death 4 (PDCD4) in autophagy regulation in the pathogenesis of diabetic kidney disease (DKD) in vivo and in vitro was described. It was found that Pdcd4 mRNA and protein was upregulated in the streptozotocin (STZ)-induced DKD rats. In addition, a unilateral ureteral obstruction mouse model displayed an upregulation of PDCD4 in the disease group. kidney biopsy samples of human DKD patients showed an upregulation of PDCD4. Furthermore, western blotting of the STZ-induced DKD rat tissues displayed a low microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, as compared to the control. It was found that albumin overload in cultured PTEC could upregulate the expression of PDCD4 and p62, and decrease the expression of LC3-II and autophagy-related 5 (Atg5) proteins. The knockout of Pdcd4 in cultured PTECs could lessen albumin-induced dysfunctional autophagy as evidenced by the recovery of Atg5 and LC3-II protein. The forced expression of PDCD4 could further suppress the expression of crucial autophagy-related gene Atg5. Herein, endogenous PDCD4 was shown to promote proteinuria-induced dysfunctional autophagy by negatively regulating Atg5. PDCD4 might therefore be a potential therapeutic target in DKD.

scholarly journals Exaggerated inflammation, impaired host defense, and neuropathology in progranulin-deficient mice

2009 ◽  
Vol 207 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Fangfang Yin ◽  
Rebecca Banerjee ◽  
Bobby Thomas ◽  
Ping Zhou ◽  
Liping Qian ◽  
...  
Keyword(s):  
Host Defense ◽  
Hippocampal Slices ◽  
Interleukin 10 ◽  
Biological Processes ◽  
Listeria Monocytogenes Infection ◽  
The Brain ◽  
Deficient Mice

Progranulin (PGRN) is a widely expressed protein involved in diverse biological processes. Haploinsufficiency of PGRN in the human causes tau-negative, ubiquitin-positive frontotemporal dementia (FTD). However, the mechanisms are unknown. To explore the role of PGRN in vivo, we generated PGRN-deficient mice. Macrophages from these mice released less interleukin-10 and more inflammatory cytokines than wild type (WT) when exposed to bacterial lipopolysaccharide. PGRN-deficient mice failed to clear Listeria monocytogenes infection as quickly as WT and allowed bacteria to proliferate in the brain, with correspondingly greater inflammation than in WT. PGRN-deficient macrophages and microglia were cytotoxic to hippocampal cells in vitro, and PGRN-deficient hippocampal slices were hypersusceptible to deprivation of oxygen and glucose. With age, brains of PGRN-deficient mice displayed greater activation of microglia and astrocytes than WT, and their hippocampal and thalamic neurons accumulated cytosolic phosphorylated transactivation response element DNA binding protein–43. Thus, PGRN is a key regulator of inflammation and plays critical roles in both host defense and neuronal integrity. FTD associated with PGRN insufficiency may result from many years of reduced neutrotrophic support together with cumulative damage in association with dysregulated inflammation.

scholarly journals Elucidating the role of leptin in systemic inflammation: a study targeting physiological leptin levels in rats and their macrophages

2017 ◽  
Vol 313 (5) ◽  
pp. R572-R582 ◽  
Author(s):  
Elizabeth A. Flatow ◽  
Evilin N. Komegae ◽  
Monique T. Fonseca ◽  
Camila F. Brito ◽  
Florin M. Musteata ◽  
...  
Keyword(s):  
Food Deprivation ◽  
Systemic Inflammation ◽  
Peritoneal Macrophages ◽  
Tnf Α ◽  
Macrophage Subpopulations ◽  
Limited Food ◽  
The Brain

To elucidate the role of leptin in acute systemic inflammation, we investigated how its infusion at low, physiologically relevant doses affects the responses to bacterial lipopolysaccharide (LPS) in rats subjected to 24 h of food deprivation. Leptin was infused subcutaneously (0–20 μg·kg−1·h−1) or intracerebroventricularly (0–1 μg·kg−1·h−1). Using hypothermia and hypotension as biomarkers of systemic inflammation, we identified the phase extending from 90 to 240 min post-LPS as the most susceptible to modulation by leptin. In this phase, leptin suppressed the rise in plasma TNF-α and accelerated the recoveries from hypothermia and hypotension. Suppression of TNF-α was not accompanied by changes in other cytokines or prostaglandins. Leptin suppressed TNF-α when infused peripherally but not when infused into the brain. Importantly, the leptin dose that suppressed TNF-α corresponded to the lowest dose that limited food consumption; this dose elevated plasma leptin within the physiological range (to 5.9 ng/ml). We then conducted in vitro experiments to investigate whether an action of leptin on macrophages could parallel our in vivo observations. The results revealed that, when sensitized by food deprivation, LPS-stimulated peritoneal macrophages can be inhibited by leptin at concentrations that are lower than those reported to promote cytokine release. It is concluded that physiological levels of leptin do not exert a proinflammatory effect but rather an anti-inflammatory effect involving selective suppression of TNF-α via an action outside the brain. The mechanism of this effect might involve a previously unrecognized, suppressive action of leptin on macrophage subpopulations sensitized by food deprivation, but future studies are warranted.

scholarly journals Down-regulation of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene by insulin: the role of the forkhead transcription factor FKHRL1

2002 ◽  
Vol 366 (1) ◽  
pp. 289-297 ◽  
Author(s):  
Alícia NADAL ◽  
Pedro F. MARRERO ◽  
Diego HARO
Keyword(s):  
Ketone Bodies ◽  
Control Site ◽  
Luciferase Reporter ◽  
Acid Oxidation ◽  
Transcription Start ◽  
Forkhead Transcription Factor ◽  
The Brain

Normal physiological responses to carbohydrate shortages cause the liver to increase the production of ketone bodies from the acetyl-CoA generated from fatty acid oxidation. This allows the use of ketone bodies for energy, thereby preserving the limited glucose for use by the brain. This adaptative response is switched off by insulin rapidly inhibiting the expression of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (HMGCS2) gene, which is a key control site of ketogenesis. We decided to investigate the molecular mechanism of this inhibition. In the present study, we show that FKHRL1, a member of the forkhead in rhabdosarcoma (FKHR) subclass of the Fox family of transcription factors, stimulates transcription from transfected 3-hydroxy-3-methylglutaryl-CoA synthase promoter-luciferase reporter constructs, and that this stimulation is repressed by insulin. An FKHRL1-responsive sequence AAAAATA, located 211bp upstream of the HMGCS2 gene transcription start site, was identified by deletion analysis. It binds FKHRL1 in vivo and in vitro and confers FKHRL1 responsiveness on homologous and heterologous promoters. If it is mutated, it partially blocks the effect of insulin in HepG2 cells, both in the absence and presence of overexpressed FKHRL1. These results suggest that FKHRL1 contributes to the regulation of HMGCS2 gene expression by insulin.

scholarly journals Placenta Defects and Embryonic Lethality Resulting from Disruption of Mouse Hydroxysteroid (17-β) Dehydrogenase 2 Gene

2008 ◽  
Vol 22 (3) ◽  
pp. 665-675 ◽  
Author(s):  
Pia Rantakari ◽  
Leena Strauss ◽  
Riku Kiviranta ◽  
Heidi Lagerbohm ◽  
Jenni Paviala ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Basal Layer ◽  
Embryonic Lethality ◽  
Cellular Density ◽  
Targeted Gene Disruption ◽  
Structural Abnormalities ◽  
The Brain

Abstract Hydroxysteroid (17-β) dehydrogenase 2 (HSD17B2) is a member of aldo-keto reductase superfamily, known to catalyze the inactivation of 17β-hydroxysteroids to less active 17-keto forms and catalyze the conversion of 20α-hydroxyprogesterone to progesterone in vitro. To examine the role of HSD17B2 in vivo, we generated mice deficient in Hsd17b2 [HSD17B2 knockout (KO)] by a targeted gene disruption in embryonic stem cells. From the homozygous mice carrying the disrupted Hsd17b2, 70% showed embryonic lethality appearing at the age of embryonic d 11.5 onward. The embryonic lethality was associated with reduced placental size measured at embryonic d 17.5. The HSD17B2KO mice placentas presented with structural abnormalities in all three major layers: the decidua, spongiotrophoblast, and labyrinth. Most notable was the disruption of the spongiotrophoblast and labyrinthine layers, together with liquid-filled cysts in the junctional region and the basal layer. Treatments with an antiestrogen or progesterone did not rescue the embryonic lethality or the placenta defect in the homozygous mice. In hybrid background used, 24% of HSD17B2KO mice survived through the fetal period but were born growth retarded and displayed a phenotype in the brain with enlargement of ventricles, abnormal laminar organization, and increased cellular density in the cortex. Furthermore, the HSD17B2KO mice had unilateral renal degeneration, the affected kidney frequently appearing as a fluid-filled sac. Our results provide evidence for a role for HSD17B2 enzyme in the cellular organization of the mouse placenta.

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